WO2009137158A1

WO2009137158A1 - System and method for liquid cooling of components

Info

Publication number: WO2009137158A1
Application number: PCT/US2009/036355
Authority: WO
Inventors: Nathan P. Lower; Ross K. Wilcoxon; Qizhou Yao; David W. Dlouhy; John A. Chihak; David W. Cripe; Bryan S. Mccoy; James R. Wooldridge; Anthony J. Strzelczyk
Original assignee: Rockwell Collins, Inc.
Priority date: 2008-05-06
Filing date: 2009-03-06
Publication date: 2009-11-12

Abstract

A circuit board may include a pump and a channel. The channel may include a liquid metal and a coating. The liquid metal may be pumped through the channel by the pump and the coating reduces diffusion and chemical reaction between the liquid metal and at least portions of the channel. The liquid metal may carry thermal energy to act as a heat transfer mechanism between two or more locations on the substrate. The substrate may include electrical interconnects to allow electrical components to be populated onto the substrate to form an electronics assembly. The pump may be driven by electric current that is utilized by one or more electronic components on the circuit board.

Description

SYSTEMAND METHOD FOR LIQUID COOLING OF COMPONENTS

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Application No. 12/116,126, filed May 6, 2008, U.S. Application No. 12/283,501, filed September 12, 2008, U.S. Application No. 12/283,563, filed September 12, 2008, U.S. Application No. 12/283,504, filed September 12, 2008, U.S. Application No. 12/283,502, filed September 12, 2008, and U.S. Application No. 12/284,670, filed September 24, 2008, all of which are incorporated herein by reference in their entireties.

BACKGROUND

[0002] The present application relates generally to the field of cooling electronics. More specifically, the application relates to cooling of power dissipating devices, such as electronics, using liquid metal.

[0003] There may be a growing demand to make electronic devices smaller and to operate at higher power. In some applications, including computers, peak power densities may be reaching 400-500 W/cm2 and climbing. As a result, it may be becoming increasingly more difficult to thermally manage these devices. Increasing temperatures often lead to decreased efficiency and reliability.

[0004] Conventional thermal management techniques such as forced air cooling, liquid cooling, spray cooling, and thermoelectric cooling may adequately cool the electronic device in some cases, but these techniques may be complicated, unreliable, orientation sensitive, or unsuitable for volume-constrained systems. The use of passive heat spreading materials and heat pipes may also adequately cool the electronic device, but increasing thermal path length, orientation effects and high device power may render these techniques insufficient. Conventional techniques may no longer provide adequate cooling for advanced high power electronic systems.

[0005] Thus there may be a need for a low cost cooling system for power dissipating systems, such as high power electronic systems. Further, there may be a need for a simple and reliable cooling system that does not add significant cost and power requirements. Further still, there may be a need for an integrated thermal management technique for spreading heat from a circuit board. Yet further, there may be a need for a thermal management system for portable applications, including military applications, which may be smaller in size and weight.

[0006] The present application further relates to the field of thermal management and particularly to a mechanically compliant thermal spreader with an embedded cooling loop for containing and circulating a liquid such as an electrically-conductive liquid. Currently available thermal spreaders may not provide a desired level of performance. Thus, it would be desirable to provide a thermal spreader which addresses the shortcomings of currently available solutions.

[0007] The present application further relates to the field of thermal management and particularly to a fabrication process for a flexible, thin thermal spreader. Current fabrication processes for thermal spreaders may not provide a thermal spreader having a desired level of performance/desired performance characteristics. Thus, it would be desirable to provide a thermal spreader fabrication process which addresses the shortcomings of currently available solutions.

[0008] The present application further relates to the field of thermal management and particularly to a thin, solid-state mechanism for pumping liquids such as electrically conductive liquids in a thermal spreader such as a mechanically flexible thermal spreader. Currently mechanisms for pumping/circulating liquids in cooling loops may not provide a desired level of performance. Thus, it would be desirable to provide a pumping mechanism which addresses the shortcomings of currently available solutions. [0009] The present application further relates to the field of thermal management and particularly to a flexible flow channel for a modular liquid-cooled thermal spreader. Currently available thermal spreaders may not provide a desired level of performance. Thus, it would be desirable to provide a thermal spreader which addresses the shortcomings of currently available solutions.

SUMMARY

[0010] One embodiment relates to a circuit board including a pump and a channel. The channel includes a liquid metal and a coating. The liquid metal is pumped through the channel by the pump and the coating reduces diffusion (or alloying) between the liquid metal and at least portions of the channel. [0011] Another embodiment relates to a circuit board including one or more electrodes, one or more magnets, and a channel. The channel includes a liquid metal and a coating.

The liquid metal is pumped through the channel by an electromagnetic force generated by the one or more electrodes and one or more magnets and the coating reduces diffusion or alloying between the liquid metal and metallic components in the channel.

[0012] Another embodiment relates to a circuit board including channel means for containing a liquid metal, pump means for pumping the liquid metal through the channel means, and coating means for reducing diffusion between the liquid metal and other components in the channel.

[0013] Another embodiment relates to a circuit board including a device to be cooled and a channel. The liquid metal may be pumped through the channel by an electromagnetic pump mechanism associated with the device to be cooled.

[0014] Another embodiment relates to a circuit board including an electromagnetic pumping mechanism including one or more electrodes, one or more magnets, and a channel.

The channel may include a liquid metal and a coating. The liquid metal may be pumped through the channel by an electromagnetic force generated by the one or more electrodes and one or more magnets.

[0015] Another embodiment relates to a circuit board including channel means for containing a liquid metal, and pump means for pumping the liquid metal through the channel means.

[0016] Another embodiment relates to a thermal spreader, including: a mechanically flexible substrate, the mechanically flexible substrate forming an internal channel, the internal channel being configured for containing a liquid such as an electrically-conductive liquid, the internal channel being further configured to allow for closed-loop flow of the electrically-conductive liquid within the internal channel; and a pump, the pump configured for being connected to the mechanically flexible substrate, the pump being further configured for circulating the electrically-conductive liquid within the internal channel, wherein the thermal spreader is configured for being connected to a heat source and a heat sink, the thermal spreader being further configured for directing thermal energy from the heat source to the heat sink via the electrically-conductive liquid.

[0017] Another embodiment relates to a thermal spreader, including: a mechanically flexible substrate, the mechanically flexible substrate forming an internal channel, the internal channel being configured for containing a liquid such as an electrically-conductive liquid, the internal channel being further configured to allow for closed-loop flow of the electrically-conductive liquid within the internal channel, the mechanically flexible substrate including a surface configured for contacting the electrically-conductive liquid, said surface of the mechanically flexible substrate being coated with a material such as alkali silicate glass, at least a portion of the mechanically flexible substrate being constructed of an organic material; a pump, the pump configured for being connected to the mechanically flexible substrate, the pump being further configured for circulating the electrically-conductive liquid within the internal channel; and a rigid metal insert, the rigid metal insert configured for being integrated with the mechanically flexible substrate, the rigid metal insert being further configured for promoting thermal energy transfer to the electrically-conductive liquid and for promoting thermal energy transfer from the electrically-conductive liquid, said rigid metal insert including a surface configured for contacting the electrically-conductive liquid, said surface of the rigid metal insert being coated with a material such as alkali silicate glass, wherein the thermal spreader is configured for being connected to a heat source and a heat sink, the thermal spreader being further configured for directing thermal energy from the heat source to the heat sink via the electrically-conductive liquid.

[0018] Another embodiment relates to a method for providing a thermal spreader, said method including: fabricating a mechanically flexible substrate, said mechanically flexible substrate forming an internal channel configured for containing and allowing closed-loop flow of a liquid such as an electrically-conductive liquid, at least a portion of the mechanically flexible substrate being constructed of an organic material; integrating a pump with the mechanically flexible substrate, said pump configured for circulating the electrically-conductive liquid within the internal channel; and fabricating a plurality of rigid metal inserts, each rigid metal insert configured for being integrated with the mechanically flexible substrate for promoting the transfer of thermal energy both to and from the electrically conductive liquid, wherein the thermal spreader is configured for being connected to a heat source and a heat sink, the thermal spreader being further configured for directing thermal energy from the heat source to the heat sink via the electrically-conductive liquid.

[0019] Another embodiment relates to a method for fabricating a thermal spreader, including: laminating a plurality of layer portions together to fabricate a mechanically flexible substrate; providing an internal channel within the mechanically flexible substrate, the internal channel configured for containing a liquid such as an electrically-conductive liquid, the internal channel being further configured to allow for closed-loop flow of the electrically-conductive liquid within the internal channel; integrating a pump with the mechanically flexible substrate; fabricating a plurality of rigid metal inserts; forming a plurality of extension portions on a surface of each rigid metal insert included in the plurality of rigid metal inserts; and connecting the plurality of rigid metal inserts to the mechanically flexible substrate.

[0020] Another embodiment relates to a method for fabricating a plurality of thermal spreaders, including: laminating a plurality of layer sheets together to fabricate a mechanically flexible substrate sheet; dicing the mechanically flexible substrate sheet to form a plurality of mechanically flexible substrates; providing an internal channel within each mechanically flexible substrate included in the plurality of mechanically flexible substrates, each internal channel configured for containing a liquid such as an electrically- conductive liquid, each internal channel being further configured to allow for closed-loop flow of the electrically-conductive liquid within the internal channel; and integrating a pump with each mechanically flexible substrate included in the plurality of mechanically flexible substrates, wherein each mechanically flexible substrate included in the plurality of mechanically flexible substrates is at least partially constructed of organic materials. [0021] Another embodiment relates to a method for fabricating a plurality of thermal spreaders, including: laminating a plurality of layer sheets together to fabricate a mechanically flexible substrate sheet; dicing the mechanically flexible substrate sheet to form a plurality of mechanically flexible substrates; providing an internal channel within each mechanically flexible substrate included in the plurality of mechanically flexible substrates, each internal channel configured for containing a liquid such as an electrically- conductive liquid, each internal channel being further configured to allow for closed-loop flow of the electrically-conductive liquid within the internal channel; integrating a pump with each mechanically flexible substrate included in the plurality of mechanically flexible substrates; fabricating a plurality of rigid metal inserts; forming a plurality of extension portions on a surface of each rigid metal insert included in the plurality of rigid metal inserts; and connecting the plurality of rigid metal inserts to the plurality of mechanically flexible substrates.

[0022] Another embodiment relates to a magnetic pump for integration with a mechanically flexible thermal spreader, said magnetic pump including: a casing, the casing configured for being connected to a mechanically flexible substrate of the thermal spreader; and a plurality of magnets, the plurality of magnets configured for being integrated with and at least partially enclosed by the casing, the plurality of magnets configured for applying a magnetic field to a liquid such as an electrically-conductive liquid, said magnets further configured for implementation with a plurality of electrodes, said electrodes being integrated within the mechanically flexible substrate for generating an electrical current flow through said liquid via a voltage applied across said electrodes, said magnets, in combination with said electrodes, configured for providing a pumping force for circulating the electrically-conductive liquid within an internal channel of an electrically-conductive cooling loop of the mechanically flexible substrate for promoting thermal conductivity of the thermal spreader.

[0023] Another embodiment relates to a magnetic pump assembly for integration with a mechanically flexible thermal spreader, said magnetic pump assembly including: a casing, the casing configured for being connected to a mechanically flexible substrate of the thermal spreader; a plurality of magnets, the plurality of magnets configured for being integrated with and at least partially enclosed by the casing, the plurality of magnets configured for applying a magnetic field to a liquid such as an electrically-conductive liquid, said magnets further configured for implementation with a plurality of electrodes, said electrodes being integrated within the mechanically flexible substrate for generating an electrical current flow through said liquid via a voltage applied across said electrodes, said magnets, in combination with said electrodes, configured for providing a pumping force for circulating the electrically-conductive liquid within an internal channel of an electrically- conductive cooling loop of the mechanically flexible substrate; and a rigid metal insert, the rigid metal insert configured for being integrated with the casing, wherein said assembly is configured for promoting local thermal conductivity of the thermal spreader. [0024] Another embodiment relates to a magnetic pump for integration with a thermal spreader such as a mechanically flexible thermal spreader, said magnetic pump including: a casing, the casing configured for being connected to a mechanically flexible substrate of the thermal spreader; a plurality of magnets, the plurality of magnets configured for being integrated with and at least partially enclosed by the casing, the plurality of magnets configured for applying a magnetic field to a liquid such as an electrically-conductive liquid, said magnets further configured for implementation with a plurality of electrodes, said electrodes being integrated within the mechanically flexible substrate for generating an electrical current flow through said liquid via a voltage applied across said electrodes, said magnets, in combination with said electrodes, configured for providing a pumping force for circulating the electrically-conductive liquid within an internal channel of an electrically- conductive cooling loop of the mechanically flexible substrate for promoting thermal conductivity of the thermal spreader, wherein the casing is configured with an input port and an output port, the casing being configured with a plurality of magnet flow channels, said magnet flow channels being located proximal to the output port, said magnet flow channels being further configured for allowing the electrically-conductive liquid to flow through the pump in a first direction, said casing being further configured with a plurality of channel walls, said channel walls configured for separating the magnet flow channels, said channel walls being configured for preventing the generated electrical current flow through said liquid from flowing in a direction generally perpendicular to the first direction, thereby promoting pumping power efficiency of the magnetic pump.

[0025] Another embodiment relates to a flexible liquid cooling loop for providing a thermal path between a heat source surface and a heat sink surface, including: a plurality of mechanically rigid tubing sections, at least one mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections being configured for contacting the heat source surface, at least one mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections being configured for contacting the heat sink surface; and a plurality of mechanically flexible tubing sections, the plurality of mechanically flexible tubing sections configured for connecting the plurality of mechanically rigid sections to form the loop, wherein the loop is configured for containing a liquid, said loop being further configured for promoting transfer of thermal energy from the heat source surface to the heat sink surface via the loop.

[0026] Another embodiment relates to a flexible liquid cooling loop for providing a thermal path between a heat source surface and a heat sink surface, including: mechanically flexible tubing; and a plurality of mechanically rigid tubing sections, the plurality of mechanically rigid tubing sections configured for being connected via the mechanically flexible tubing to form the loop, at least one mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections being configured for contacting the heat source surface, at least one mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections being configured for contacting the heat sink surface, wherein the loop is configured for containing a liquid, said loop being further configured for promoting transfer of thermal energy from the heat source surface to the heat sink surface via the loop, said loop being further configured for integration within a mechanically flexible substrate of a mechanically compliant thermal spreader.

[0027] Another embodiment relates to a liquid cooling loop, for providing a thermal path between a heat source surface and a heat sink surface, including: a plurality of mechanically rigid tubing sections, each mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections forming a first compartment and a second compartment; and a plurality of mechanically flexible tubing sections, a first set of mechanically flexible tubing sections included in the plurality of mechanically flexible tubing sections being configured for connecting the plurality of mechanically rigid tubing sections via the first compartments of each mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections, a second set of mechanically flexible tubing sections included in the plurality of mechanically flexible tubing sections being configured for connecting the plurality of mechanically rigid tubing sections via the second compartments of each mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections, the plurality of mechanically rigid tubing sections configured for being connected via the first set of mechanically flexible tubing sections and the second set of mechanically flexible tubing sections to form the loop, said first compartments and second compartments preventing physical contact of the first set of mechanically flexible tubing sections and said second set of mechanically flexible tubing sections, wherein the loop is configured for containing a liquid, said loop being further configured for promoting transfer of thermal energy from the heat source surface to the heat sink surface via the loop. [0028] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the embodiments disclosed herein. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate various embodiments and together with the general description, serve to explain the principles of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements. [0030] FIG. 1 illustrates an overhead schematic view of a circuit board with an integrated thermal management system.

[0031] FIG. 2 illustrates a thermal imaging schematic view of a thermal management system similar to that of FIG. 1.

[0032] FIG. 3 illustrates a perspective view of an electromagnetic pump for pumping liquid metal in the thermal management system of FIG. 1.

[0033] FIG. 4 illustrates a thermal imaging schematic view of thermal management system of FIG. 1.

[0034] FIG. 5 illustrates a thermal imaging schematic view of a thermal management system including a copper insert.

[0035] FIG. 6 illustrates a side cross section view through a portion of the thermal management system of FIG. 1.

[0036] FIG. 7 illustrates side cross section view through another portion of the thermal management system of FIG. 1.

[0037] FIG. 8 illustrates a side view of a circuit board with an integrated thermal management system.

[0038] FIG. 9 illustrates an overhead view of a circuit board with an integrated thermal management system.

[0039] FIG. 10 illustrates a high-level operational flow diagram.

[0040] FIG. 11 illustrates a high-level operational flow diagram.

[0041] FIG. 12 is a side elevation view of a thermal spreader in accordance with an exemplary embodiment.

[0042] FIG. 13 is a sectional view of the thermal spreader of FIG. 12, said sectional view showing in enlarged detail extension portions of an insert of the thermal spreader in accordance with an exemplary embodiment.

[0043] FIG. 14 is a side elevation view of a thermal spreader in accordance with an exemplary embodiment.

[0044] FIG. 15 is a bottom plan cross-sectional view of the thermal spreader shown in

FIG. 14 in accordance with an exemplary embodiment.

[0045] FIG. 16 is a side elevation view of a thermal spreader assembly in accordance with an exemplary embodiment.

[0046] FIG. 17 is a flow chart illustrating a method for fabricating a thermal spreader in accordance with an exemplary embodiment. [0047] FIG. 18 is an exploded view of a thermal spreader in accordance with an exemplary embodiment.

[0048] FIG. 19 is a side elevation view of the thermal spreader shown in FIG. 18 when assembled.

[0049] FIG. 20 is a flow chart illustrating a method for fabricating a thermal spreader in accordance with an exemplary embodiment.

[0050] FIG. 21 is a flow chart illustrating a method for fabricating a plurality of thermal spreaders in accordance with an exemplary embodiment.

[0051] FIG. 22 is a view illustrating a plurality of layer sheets which may be laminated together to fabricate a mechanically flexible substrate sheet, said substrate sheet being implemented in the fabrication method shown in FIG. 21 in accordance with an exemplary embodiment.

[0052] FIG. 23 is a side elevation view of a thin, mechanically flexible thermal spreader which implements/includes a magnetic pump in accordance with an exemplary embodiment.

[0053] FIG. 24 is a cross-sectional view of a magnetic pump integrated with a mechanically flexible substrate of a thin, mechanically flexible thermal spreader in accordance with an exemplary embodiment.

[0054] FIG. 25 is a bottom plan cross-sectional view of the thermal spreader shown in

FIG. 23, said view showing a bottom surface of the ferrous casing/ferrous lens of the magnetic pump implemented/integrated with said thermal spreader in accordance with an exemplary embodiment.

[0055] FIG. 26 is a bottom plan cross-sectional view as in FIG. 25 except that said magnetic pump has been removed to illustrate a slotted portion of the mechanically flexible substrate of the thermal spreader, said slotted portion configured for receiving the magnetic pump in accordance with an exemplary embodiment.

[0056] FIG. 27 is a cross-sectional view of a magnetic pump assembly which includes a magnetic pump integrated with a thermally conductive rigid metal insert in accordance with an exemplary embodiment.

[0057] FIG. 28 is a bottom plan cross-sectional view of a mechanically flexible thermal spreader which includes/is integrated with the magnetic pump assembly shown in FIG. 27 in accordance with an exemplary embodiment. [0058] FIG. 29 is a bottom plan cross-sectional view as in FIG. 28 except that said magnetic pump assembly has been removed to illustrate a slotted portion of the mechanically flexible substrate of the mechanically flexible thermal spreader, said slotted portion configured for receiving the magnetic pump assembly in accordance with an exemplary embodiment.

[0059] FIG. 30 is a cutaway view of a magnetic pump integrated with an internal channel of a thermal spreader, said view illustrating a flow direction of electrically-conductive liquid through the internal channel and magnetic pump, said view further illustrating an ideal electrical current flow/current path relative to said liquid flow direction, said current flow generated via said electrodes of the thermal spreader.

[0060] FIG. 31 is a cutaway view of a magnetic pump integrated with an internal channel of a thermal spreader, said view illustrating a flow direction of electrically-conductive liquid through the internal channel and magnetic pump, said view further illustrating a curved electrical current flow/current path relative to said liquid flow direction, said current flow generated via said electrodes of the thermal spreader.

[0061] FIG. 32 is a cutaway view of a magnetic pump in accordance with an exemplary embodiment, integrated with an internal channel of a liquid cooling loop of a mechanically flexible substrate of a thin mechanically flexible thermal spreader, said magnetic pump including a plurality of magnet flow channels/dielectric flow straightener channels separated by channel walls, said view further illustrating a current path produced when said magnetic pump is implemented as shown.

[0062] FIG. 33 is a side elevation view of a flexible liquid cooling loop for providing a thermal path between a heat source surface and heat sink surface in accordance with an exemplary embodiment.

[0063] FIG. 34 is a cross-sectional view of a mechanically rigid tubing section of the flexible liquid cooling loop shown in FIG. 33 in accordance with an exemplary embodiment.

[0064] FIG. 35 is a side elevation view of the flexible liquid cooling loop shown in

FIG. 33 being in thermal contact with a heat source and a heat sink in accordance with an exemplary embodiment.

[0065] FIG. 36 is a side elevation view of a flexible liquid cooling loop which includes a thermoelectric generator, said flexible liquid cooling loop shown as being in thermal contact with a heat source and a heat sink in accordance with an exemplary embodiment. [0066] FIG. 37 is a side elevation view of a flexible liquid cooling loop being implemented as a thermal bridge between an electronics component of a vehicle and a mounting plate of the vehicle when said electronics component is mounted to said mounting plate via vibration isolators in accordance with an exemplary embodiment.

[0067] FIG. 38 is a top plan view of a flexible liquid cooling loop having a "watchband" configuration in accordance with an exemplary embodiment.

[0068] FIG. 39 is a side elevation view of the flexible liquid cooling loop shown in

FIG. 38 in accordance with an exemplary embodiment.

[0069] FIG. 40 is a top plan view of a flexible liquid cooling loop having a "racetrack" configuration in accordance with an exemplary embodiment.

[0070] FIG. 41 is a side elevation view of the flexible liquid cooling loop shown in

FIG. 40 in accordance with an exemplary embodiment.

[0071] FIG. 42 is a top plan view of a liquid cooling loop in accordance with an alternative exemplary embodiment.

[0072] FIG. 43 is a side elevation view of the liquid cooling loop shown in FIG. 42 in accordance with an exemplary embodiment.

[0073] FIG. 44 is a cross-sectional view of a mechanically rigid tubing section of the liquid cooling loop shown in FIGS. 42 and 43 in accordance with an exemplary embodiment.

[0074] FIG. 45 is a sectional view of an internal channel of a mechanically flexible substrate of a thermal spreader, said internal channel connected to an expandable bladder, said internal channel including a wall (shown in phantom-line view) for directing fluid flow within the channel towards said bladder in accordance with a further exemplary embodiment.

[0075] FIG. 46 is a sectional view of an internal channel of a mechanically flexible substrate of a thermal spreader in which the expandable bladder is placed on an interior wall of the internal channel in accordance with an exemplary embodiment.

[0076] FIG. 47 is a sectional view of an internal channel of a mechanically flexible substrate of a thermal spreader in which the expandable bladder is placed on an exterior wall of the internal channel in accordance with an alternative exemplary embodiment.

[0077] FIG. 48 is a bottom plan cross-sectional view of a mechanically flexible substrate having a minichannel and/or microchannel fabricated into the substrate via film-based photoresists in accordance with a further exemplary embodiment. [0078] FIG. 49 is a side elevation view of the mechanically flexible substrate shown in

FIG. 48 in accordance with an exemplary embodiment.

[0079] FIG. 50 is a bottom plan cross-sectional view of a mechanically flexible substrate which is configured for minimizing a channel-to-chassis interconnect for the substrate in accordance with an exemplary embodiment.

[0080] FIG. 51 is a schematic representation of a surface before an after the application a monomeric silica coating according to an exemplary embodiment.

[0081] FIG. 52 is a graph showing the percent temperature change for a material encapsulated with a variety of different coatings according to an exemplary embodiment.

[0082] FIG. 53 A is a sectional view of a device flip chip bonded to base according to an exemplary embodiment.

[0083] FIG. 53B is a detail cross-section of the device and base of FIG. 53A showing a coating applied to the device and other components according to an exemplary embodiment.

[0084] FIG. 53C is a sectional view of a device wire bonded to base according to an exemplary embodiment.

[0085] FIG. 53D is a detail cross-section of the device and base of FIG. 53A showing a coating applied to the device and other components according to an exemplary embodiment.

[0086] FIG. 54A is a sectional view of a device wire bonded to base and coated with an opaque coating according to an exemplary embodiment.

[0087] FIG. 54B is a sectional view of a device flip chip bonded to base and coated with an opaque coating according to an exemplary embodiment.

[0088] FIG. 55 A is a sectional view of a device bonded to base and coated with coating including particles to increase thermal conductivity according to an exemplary embodiment.

[0089] FIG. 55B is a sectional view of a device bonded to base and eat sink and coated with coating including particles to increase thermal conductivity according to an exemplary embodiment.

[0090] FIG. 56A is a sectional view of a device flip chip bonded to a base including a coating with a filler to increase the bond layer thickness of the coating according to an exemplary embodiment.

[0091] FIG. 56B is a detail cross-section of the device of FIG. 56A showing a coating with a filler to increase the bond layer thickness of the coating according to an exemplary embodiment. [0092] FIG. 57A is a sectional view of a device wire bonded to a base including a plurality of stacked chips bonded together with a coating according to an exemplary embodiment.

[0093] FIG. 57B is a detail cross-section of the device of FIG. 57A showing a plurality of stacked chips bonded together with a coating according to an exemplary embodiment.

[0094] FIG. 58A is a sectional view of a device wire bonded to a base including a coating with a low dielectric coating according to an exemplary embodiment.

[0095] FIG. 58B is a detail cross-section of the device of FIG. 58A showing a coating with a low dielectric coating according to an exemplary embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0096] Before describing in detail the particular improved system and method, it should be observed that various embodiments may include, but may be not limited to a novel structural combination of conventional data/signal processing components and communications circuits, and not in the particular detailed configurations thereof. Accordingly, the structure, methods, functions, control and arrangement of conventional components software, and circuits have, for the most part, been illustrated in the drawings by readily understandable block representations and schematic diagrams, in order not to obscure the disclosure with structural details which will be readily apparent to those skilled in the art, having the benefit of the description herein. Further, the subject matter disclosed herein may be not limited to the particular embodiments depicted in the exemplary diagrams, but should be construed in accordance with the language in the claims. [0097] Referring to FIGS. 1 and 2, according to an exemplary embodiment, a thermal management system 1OA may provide significant improvement in the thermal spreading capability of a substrate 12 including circuitry 13 as compared to passive materials and composites. The thermal management system 1OA may include a closed- loop liquid metal channel 14 in substrate 12 containing a device 16 to be cooled by a liquid such as liquid metal 20 (e.g., a liquid, an electronically conductive liquid, etc.) flowing in the liquid metal channel 14. According to various exemplary embodiments, the substrate 12 may be a printed circuit board, a thermal spreader (which may be rigid, semi-rigid, or mechanically flexible and/or compliant), or any other substrate to which at least one power dissipating device, such as an electronic component, may be attached or interfaced. According to various exemplary embodiments, the device 16 may be a high power electronic circuit (e.g., a rectifier, an inverter, another power semiconductor device, etc.), a microprocessor, and/or any other analog or digital circuit that generates heat.

[0098] The liquid metal 20 may be circulated through liquid metal channel 14 using a magnetic or electromagnetic (EM) pump 18. The pump 18 may be inserted into or attached to the substrate at a feed-through or cavity 19. As the liquid metal 20 flows, it may draw heat away from device 16 and spread the heat throughout substrate 12 and/or carry the heat to a heat sink 17 that may be in contact with a heat rejection area on the circuit board. By transferring heat away from device 16, the thermal transfer may be significantly improved over conventional passive thermal spreading materials, including copper. Because the liquid metal cooling may be single phase (no phase change occurs), thermal management system 1OA may not be restrained by the heat flux limits of two phase systems such as heat pipes. While the liquid metal 20 is shown by arrows to flow in a particular direction, according to other exemplary embodiments, the thermal management system could be configured for the liquid metal to flow in the other direction. The liquid metal channel 14 may be filled with liquid metal 20 using ports 15. The heat sink 17 may be a copper plate, another metal plate, may include cooling fins, or may be any other device capable promoting heat exchange. The circuitry 13 may be high or low power electronic circuits and may also be cooled using liquid metal channel 14.

[0099] Referring specifically to FIG. 2, as an example, the liquid metal 20 generally flows through liquid metal channel 14 at a first or lowest temperature (e.g., between 15 and 25 degrees Celsius (C), between 18 and 22 degrees C, between 20 and 21 degrees C, at about 20 or 21 degrees C, etc.) in thermal management system 1OA (e.g., a system for controlling (raising, lowering, etc.) the temperature of one or more components). A substantial portion of substrate 12 and at least a portion of device 16 may be at a second temperature that may be higher than the first temperature (e.g., between 20 and 24 degrees C, between 21 and 23 degrees C, at about 22 degrees C, below 20 degrees C, etc.). A portion of device 16 may be at a third temperature that may be higher than the second temperature (e.g., between 22 and 26 degrees C, between 23 and 25 degrees C, at about 24 degrees C, etc.). A portion of device 16 may be at a fourth temperature that may be higher than the third temperature (e.g., between 23 and 27 degrees C, between 24 and 26 degrees C, at about 25 degrees C, etc.). A portion of device 16 may be at a fifth temperature that may be higher than the fourth temperature (e.g., between 25 and 30 degrees C, between 26 and 29 degrees C, at about 28 degrees C, above 30 degrees C, etc.). It may be noted that while FIG. 2 illustrates a single heat dissipating device 16, according to other exemplary embodiments, the substrate 12 may absorb dissipated heat from more than one component.

[0100] According to various exemplary embodiments, the liquid metal 20 may be an alloy, such as a Gallium-Indium-Tin alloy. According to other exemplary embodiments, alternative liquid metal 20 may be used, including alloys containing any combination of the following: gallium, indium, tin, bismuth, lead, sodium, and potassium. According to some exemplary embodiments, the Gallium-Indium-Tin alloy may be a eutectic composition (e.g. the lowest melting point within the compositional series) with a low boiling point. According to some exemplary embodiments, the Gallium-Indium-Tin alloy may be Galinstan®. Galinstan® may be a generally non-flammable, non-toxic, environmentally friendly liquid metal that may be often used as a mercury replacement in medical equipment. Galinstan® may be generally stable from -19 degrees C to greater than 1300 degrees C, has approximately thirty times the thermal conductivity of water, and may be insoluble to water and organic solvents. The high boiling point of Galinstan® (greater than 1300 degrees C) ensures that it will remain in a liquid state under temperatures and pressures likely to be encountered in electronics cooling.

[0101] Referring to FIG. 3, pump 18 may be an electromagnetic pump to circulate a liquid metal 20 through thermal management system 1OA. The pump 18 may provide quiet or silent operation, high reliability, orientation independence, little to no vibration, low power dissipation, and a controllable flow rate for adjustment of thermal spreading capability. The pump 18 may include a ferrous yoke for containing and directing the magnetic field within the yoke and through the liquid metal channel 14 between north and south poles of magnets 22. A pair of electrodes 24 may transmit a current 38 across liquid metal 20 in a direction perpendicular to the magnetic field generated by magnets 22. The movement of the current 38 across the magnetic field may impart a force on the liquid metal 20 that may be perpendicular to both the magnetic field and the current 38. The amount of feree generated follows the following equation: [0102] (1) F = I * L x B

[0103] Where I may be current 38 (in amps), L may be a vector, whose magnitude may be the length of the current path (in meters), x may be the vector cross product, and B may be the magnetic field vector measured in Teslas.

[0104] The magnitude of force may be represented by the variable F, the magnitude of the magnetic field may be represented by the variable B, the amount of current may be represented by the variable I, and the electrode spacing may be represented by the variable L. The pressure of the liquid metal 20 flow may be calculated with the following equation:

[0105] (2) P = -^-

Lxh

[0106] The pressure may be represented by the variable P, the force by the variable F, the spacing of electrodes 24 by the variable L, and the height of liquid metal channel 14 by the variable h.

[0107] The pump 18 may be made to occupy a small volume (e.g., approximately one cubic centimeter, less than one cubic centimeter, less than 10 cubic centimeters, greater than 1 cubic centimeter, etc.) and may pump liquid metal 20 with electrical power of less than 10 mW, less than 100 mW, less than 500 mW, etc. The pump 18 includes no moving parts, may require little to no maintenance, may be orientation independent, and may be generally stable at air pressures down to 10-8 Torr at 500 degrees Celsius. According to various exemplary embodiments, one or both of magnets 22 may be permanent magnets and/or electromagnets including coils to induce a magnetic field. While two electrodes 24 are shown, according to other exemplary embodiments, the current may be generated by a single electrode and a ground, or more than two electrodes. While two magnets 22 are shown, according to other exemplary embodiments a single magnet with a pole extending over opposite sides of liquid metal channel 14, or more than two magnets could be used. According to various exemplary embodiments, pump 18 may operate at less than about IW, between about 100 mW and about 500 mW, less than 500 mw, less than 100 mw, etc. The pump 18 may be coupled to a processor, a user interface, or other digital or analog circuitry to control electric current flow and thereby adjust the pump flow.

[0108] A coating may be applied to the inner and/or outer perimeter of the liquid metal channel 14 to provide a passivation within the liquid metal channel 14. According to some exemplary embodiments, the coating may reduce alloying, diffusion, or chemical reaction between components in the channel (e.g., metallic components) and the alloy. The coating may provide at least a substantially hermetic seal around the liquid metal 20 to separate it from the substrate 12 itself and/or the substrate circuitry 13. According to various exemplary embodiments, the coating may be a thermally conductive coating capable of minimizing the thermal resistance between the liquid metal 20 and the substrate 12 or circuitry 13. The coating may be composed of any material or materials capable of passivating the liquid metal 20 from the substrate 12 or circuitry 13, capable of promoting thermal conductivity between the liquid metal 20 and the substrate 12 or circuitry 13, and/or capable of being applied to the liquid metal channel 14 of the substrate 12. According to some exemplary embodiments, the coating may only be applied to metallic portions of the liquid metal channel 14 that may be in contact with the liquid metal 20. [0109] According to other exemplary embodiments, the coating may be a coating described in US Patent Application no. 11/508,782 filed on August 23, 2006 and entitled "Integrated Circuit Protection and Ruggedization Coatings and Methods," US Patent Application no. 11/784,158 filed on April 5, 2007 and entitled "Hermetic Seal and Hermetic Connector Reinforcement and Repair with Low temperature Glass Coatings," US Patent Application no. 11/732,982 filed on April 5, 2007 and entitled "A Method for Providing Near-Hermetically Coated Integrated Circuit Assemblies," US Patent Application no. 11/732,981 filed on April 5, 2007 and entitled "A Method for Providing Near- Hermetically Coated, Thermally Protected Integrated Circuit Assemblies," US Patent Application no. 11/784, 932 filed on April 10, 2007 and entitled "Integrated Circuit Tampering Protection and Reverse Engineering Prevention Coatings and Methods," and/or US Patent Application no. 11/959,225 filed on December 18, 2007 and entitled "Adhesive Applications Using Alkali Silicate Glass for Electronics," each of which is herein incorporated by reference in its entirety.

[0110] Where an electrically conductive contact to the liquid metal 20 may be required, such as at the electrodes 24 within the pump 18, an electrically conductive coating may be used, which consists of nickel, tantalum, or tungsten metal. Similarly, solid Nickel, Tungsten, or Tantalum wires may be used for the electrodes. [0111] Referring to FIG. 4, the temperature of substrate 12 and device 16 may be significantly higher (e.g. Temps 4 and 5) when pump 18 is turned off in thermal management system 1OA. Only the small portion of substrate 12 may be at the first or lowest temperature (e.g. Temp 1) with a larger portion of substrate 12 at the second temperature (e.g. Temp 2) and a substantial portion of substrate 12 at the third temperature (e.g. Temp 3). The device 16 may operates at elevated temperatures (e.g. Temps 4 and 5) when substrate 12 is not pumping liquid metal. Such a condition may affect performance and/or reliability.

[0112] Referring to FIG. 5, according to one exemplary embodiment, the temperature of device 16 may be greatly reduced with the sealed liquid metal channel 14 in thermal management system 1OA as compared to a copper heat sink 26 of the same dimension (as shown in FIG 5). The temperature of device 16 may rise about eighty degrees C over the copper heat sink 26 temperature but may rise only about 18.5 degrees Celsius over the cold plate temperature on the substrate 12 of FIG. 1. In the substrate 12, device 16 may contribute to the majority of the thermal gradient. The temperature difference across liquid metal channel 14 may be about 1.6 degrees C as compared to about seventy degrees C on copper heat sink 26. This difference represents a nearly forty- four times improvement in effective thermal conductivity over a copper heat sink 26. With smaller liquid metal channel 14 dimensions and/or longer liquid metal channel 14 length, the thermal conductivity may be greater.

[0113] Referring to FIGS. 6 and 7, a cross-sectional view of the thermal management system 1OA of FIG. 1 is presented. The thermal management system 1OA may include multiple layers. The thermal management system 1OA may include a substrate 12 which may include a base layer 28 that defines liquid metal channel 14 and a top layer 30 that covers liquid metal channel 14. The circuitry 13, device 16, and heat sink 17 may be attached to top layer 30.

[0114] According to various exemplary embodiments, the liquid metal channel 14 may be formed by etching substrate 12 (e.g., wet etching, plasma etching, silk screen printing, photoengraving, PCB milling, die cutting, stamping, etc.) during fabrication. The substrate 12 may include any material used to make circuit boards or heat sinks including copper, any conductive material, or any non-conductive material. In one example, substrate 12 may include thermally conductive inserts or other devices for increased heat dissipation. [0115] For example, the etching may etch away a base layer 28 of copper (or other layer) on top of a non-conductive layer to form the liquid metal channel 14. Alternatively, the etching may etch away a base layer 28 of non-conductive material (or both a layer of copper and a non-conductive layer) to form liquid metal channel 14. The liquid metal channel 14 may then be coated and/or sealed with a thermally conductive coating. Thereafter, another conductive (e.g., a heat sink 17) or non-conductive layer (e.g., top layer 30) may be placed on top of the etched base layer 28. Alternatively, the etched base layer 28 may be placed on top of another layer or between two other layers. The non-etched layers may also include a coating to facilitate greater thermal conductivity and/or sealing with thermal management system 1OA. The coating may be applied to liquid metal channel 14, base layer 28 and/or top layer 30 during etching or after etching and before assembly. The coating may also be applied after partial assembly (e.g., after an etched layer is placed on a base layer) and before any additional layers are added.

[0116] According to various exemplary embodiments, the width of liquid metal channel 14 may be between 5 and 50 mm. According to various exemplary embodiments, the height of liquid metal channel 14 may be as small as 10 microns and as large 2000 microns. According to various exemplary embodiments, the length of liquid metal channel 14 may be between typically 5 and 200 cm. The values of these dimensions, especially the maximum values, may be primarily dictated by geometric requirements of the system that may be being thermally managed with the liquid metal channel 14 rather than limitations of the liquid metal cooling approach itself.

[0117] According to various exemplary embodiments, the general cross-sectional shape of liquid metal channel 14 may be square, rectangular, triangular, hexagonal, trapezoidal, or any other shape. While liquid metal channel 14 is shown to have a specific rectangular- shaped flow path, according to other exemplary embodiments, the path may be of any shape or direction that facilitates the cooling of device 16.

[0118] According to some exemplary embodiments, the liquid metal 20 may be added to liquid metal channel 14 during fabrication before a coating seals liquid metal channel 14 or before a top layer 30 is placed on top of an etched base layer 28. According to other exemplary embodiments, a reservoir may feed liquid metal 20 to liquid metal channel 14. The reservoir may be etched or otherwise formed into substrate 12. Alternatively, the reservoir may be external to substrate 12 (e.g., attached to substrate 12) and coupled to liquid metal channel 14. The substrate 12 may include a heat sink 17 and/or fan at or near an end of substrate 12 opposite from a heat source (e.g. a device 16) to help cool the liquid metal 20 flowing from device 16. Alternatively or additionally, an external reservoir may include a heat sink 17 and/or fan at or near an end of substrate 12 opposite from the heat source (e.g. a device 16) to help cool the liquid metal 20 flowing from device 16. [0119] Referring to FIGS. 8 and 9, a thermal management system 1OB is illustrated. Similar to thermal management system 1OA, thermal management system 1OB may include a closed- loop liquid metal channel 14 in substrate 12 containing a device 16 to be cooled by liquid metal 20 flowing in the liquid metal channel 14. According to various exemplary embodiments, the substrate 12 may be a printed circuit board, a thermal spreader (which may be rigid or mechanically flexible), or any other substrate to which at least one power dissipating device, such as an electronic component, may be attached or interfaced. According to various exemplary embodiments, the device 16 may be a high power electronic circuit (e.g., a rectifier, an inverter, another power semiconductor device, etc.), a microprocessor, and/or any other analog or digital circuit that generates heat. [0120] The liquid metal 20 may be circulated through liquid metal channel 14 using a magnetic or electromagnetic (EM) pumping mechanism 18. As the liquid metal 20 flows, it may draw heat away from device 16 and spread the heat throughout substrate 12 and/or carry the heat to a heat sink 17 that may be in contact with a heat rejection area on the circuit board. By transferring heat away from the device 16, the thermal transfer may be significantly improved over conventional passive thermal spreading materials, including copper. Because the liquid metal cooling may be single phase (no phase change occurs), thermal management system 1OA may not be restrained by the heat flux limits of two phase systems such as heat pipes. While the liquid metal 20 is shown by arrows to flow in a particular direction, according to other exemplary embodiments, the thermal management system could be configured for the liquid metal to flow in the other direction. The heat sink 17 may be a copper plate, another metal plate, may include cooling fins, or may be any other device capable promoting heat exchange. The circuitry 13 may be high or low power electronic circuits and may also be cooled using liquid metal channel 14. [0121] In contrast to thermal management system 1OA, thermal management system 1OB may not include a separate power source for the electromagnetic pump 18. Instead, the current for powering the electromagnetic pump 18 may be obtained from the power circuitry associated directly with the device 16.

[0122] For example, as shown in FIGS. 8 and 9, the device 16 may be operably coupled to current transmission circuitry 34 (e.g. device circuitry 34A and/or device circuitry 34B. The current transmission circuitry 34 may be operably coupled to the pump 18. FIGS. 8 and 9 illustrate the pump 18 operably coupled to the device circuitry 34B of device 16. However, the pump 18 may be operably coupled to the device circuitry 34A of device 16 without departing from the scope of the invention.

[0123] In such configurations, the current flowing into or out of the device 16 may provide an electromagnetic force for pumping the liquid metal 20. As the heat generated by a device 16 is generally proportional to the current provided to the device 16, such a configuration may serve to automatically control the pumping velocity of liquid metal 20 according to the current provided to the device. [0124] The pump 18 may include a ferrous yoke for containing and directing the magnetic field within the yoke and through the liquid metal channel 14 between north and south poles of magnets 22. A pair of electrodes 24 may transmit a current 38 across liquid metal 20 in a direction perpendicular to the magnetic field generated by magnets 22. The movement of the current 38 across the magnetic field may impart a force on the liquid metal 20 that may be perpendicular to both the magnetic field and the current 38.

[0125] According to various exemplary embodiments, one or both of magnets 22 may be permanent magnets and/or electromagnets including coils to induce a magnetic field. While two electrodes 24 are shown, according to other exemplary embodiments, the current may be generated by a single electrode and a ground, or more than two electrodes. While two magnets 22 are shown, according to other exemplary embodiments a single magnet with a pole extending over opposite sides of liquid metal channel 14, or more than two magnets could be used. According to various exemplary embodiments, pump 18 may operate at less than about IW, between about 100 mW and about 500 mW, less than 500 mw, less than 100 mw, etc. The pump 18 may be coupled to a processor, a user interface, or other digital or analog circuitry to control electric current flow and thereby adjust the pump flow. [0126] It will be recognized one knowledgeable in the art that pump 18 may be disposed in either an upstream or downstream position in relation to the device 16 with respect to the current flow relative to the device 16 without departing from the scope of the present disclosures.

[0127] In instances where the current provided to the device 16 exceeds the current needed to provide adequate pumping action of liquid metal 20, a current shunt 36 element may be provided to reduce the current 38 applied across the liquid metal channel 14. For example, the current shunt 36 may be operably coupled to one of the electrodes 24 via electrode circuitry 34B-1. The current shunt 36 may be operably coupled to a ground plane 32 by current shunt circuitry 34B-2. In such a configuration, the amount of current provided to the electrodes 24 may be modified through the transmission characteristics of the current shunt 36 so as to control the pumping velocity range of the pump 18. [0128] The thermal management system 1OA and/or the thermal management system 1OB may provide a low cost, simple, reliable, and/or integrated method for spreading heat away from high power devices. Integrating such a technology into an electronic substrate may allow direct heat removal from high power integrated circuits (IC) and passive devices while also providing electrical interconnect to these components. While this approach could be used for almost any type of electronics packaging, specific examples of suitable applications include RF Power Amplifiers and Light Emitting Diode (LED) light arrays, which may otherwise require that a heat sink or heat spreader be bonded to the back side of the electronic substrate so that both sides of the circuit card may be populated with electronic components. Another exemplary application may include the use of an electronic substrate with embedded liquid metal cooling channels as part of an antenna array, such as a phased array antenna.

[0129] FIGS. 10 and 11 illustrate operational flows representing example operations related to proportional cooling with liquid metal. However, it should be understood that the operational flows may be executed in a number of other environments and contexts, and/or in modified versions of FIG. 1. Also, although the various operational flows are presented in the sequence(s) illustrated, it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently.

[0130] Referring to FIG. 10, after a start operation, an exemplary operational flow 1000 moves to a transmitting operation 1202. Operation 1202 illustrates transmitting a current to a device. For example, as shown in FIGS. 8 and 9, a device circuitry 34A may transmit a current from a power source (not shown) to a device 16.

[0131] Operation 1204 illustrates transmitting a current from the device across a circuit board channel comprising a liquid metal. For example, as shown in FIGS. 8 and 9, device circuitry 34B may transmit a current to pump 18 from the device 16. The pump 18 may transmit a current across liquid metal channel 14 and through liquid metal 20.

[0132] FIG. 10 further illustrates an example embodiment where the example operational

1204 may include at least one additional operation. Additional operations may include an operation 1206, operation 1208, operation 1210 and/or operation 1212.

[0133] Operation 1206 illustrates transmitting a current from the device to an electrode.

For example, as shown in FIGS. 8 and 9, device circuitry 34B- 1 may transmit a current to one or more electrodes 24 of pump 18.

[0134] Operation 1208 illustrates inducing a velocity of the liquid metal associated with the current transmitted across the circuit board channel comprising the liquid metal. For example, as shown in FIGS. 8 and 9, electrodes 24 may transmit a current 38 across the liquid metal channel 14 and through liquid metal 20. The movement of current 38 may exert an electromagnetic force on the liquid metal 20 which may accelerate the liquid metal 20 to a velocity within the liquid metal channel 14.

[0135] Operation 1210 illustrates inducing a velocity in the liquid metal proportional to current usage of the device. For example, as shown in FIGS. 8 and 9, the current 38 may be an output current from device 16. As such, current 38 may be proportional to the current usage of the device 16. The resulting electromagnetic force on the liquid metal 20 (and corresponding velocity of the liquid metal 20) may be proportional to the current 38. [0136] Operation 1212 illustrates transmitting a current from the device to a current shunt. For example, as shown in FIGS. 8 and 9, device circuitry 34B may transmit a current from the device 16 to a current shunt 36. The current shunt 36 may transmit a current via current shunt circuitry 34B-2 to the ground plane 32. The amount of current 38 transmitted across the liquid metal channel 14 and through liquid metal 20 may be modified through the transmission characteristics of the current shunt 36 so as to control the pumping velocity range of the pump 18.

[0137] Referring to FIG. 11, after a start operation, an exemplary operational flow 1300 moves to a transmitting operation 1302. Operation 1302 illustrates transmitting a current from the device across a circuit board channel comprising a liquid metal. For example, as shown in FIGS. 8 and 9, a pump 18 may transmit a current received from a power source (not shown) across liquid metal channel 14 and through liquid metal 20. [0138] Operation 1304 illustrates transmitting the current transmitted across the circuit board channel comprising a liquid metal to a device. For example, as shown in FIGS. 8 and 9, device circuitry 34B may transmit a current received from pump 18 to a device 16. [0139] FIG. 11 further illustrates an example embodiment where the example operational 1302 may include at least one additional operation. Additional operations may include an operation 1306, operation 1308 and/or an operation 1310.

[0140] Operation 1306 illustrates transmitting a current to one or more electrodes. For example, as shown in FIGS. 8 and 9, one or more electrodes 24 of pump 18 may receive a current from a power source (not shown).

[0141] Operation 1308 illustrates inducing a velocity of the liquid metal associated with the current transmitted across the circuit board channel comprising the liquid metal. For example, as shown in FIGS. 8 and 9, electrodes 24 may transmit a current 38 across the liquid metal channel 14 and through liquid metal 20. The movement of current 38 may exert an electromagnetic force on the liquid metal 20 which may accelerate the liquid metal 20 to a velocity within the liquid metal channel 14.

[0142] Operation 1310 illustrates inducing a velocity in the liquid metal proportional to current usage of the device. For example, as shown in FIGS. 8 and 9, the current 38 may be an output current from device 16. As such, current 38 may be proportional to the current usage of the device 16. The resulting electromagnetic force on the liquid metal 20 (and corresponding velocity of the liquid metal 20) may be proportional to the current 38. [0143] FIG. 11 further illustrates an example embodiment where the example operational 1304 may include at least one additional operation. Additional operations may include an operation 1312.

[0144] Operation 1312 illustrates powering the device with the current transmitted across the circuit board channel comprising a liquid metal. For example, as shown in FIGS. 8 and 9, device circuitry 34B may transmit a current from the pump 18 to the device 16. The device 16 may utilize the current received from the pump 18 to power its circuitry. [0145] Referring now to FIGS. 12-50, a thermal spreader/heat spreader may be used to diffuse and transport thermal energy from a heat source, such as an electronics component on a circuit board, to a lower temperature surface, such as a chassis in which the circuit board may be mounted. A heat spreader may be constructed of a material having a high thermal conductivity, such as metal (e.g., copper, aluminum), in order to reduce thermal gradients within the heat spreader so that the heat spreader may minimize the temperature of the heat source. When thermal gradients within a heat spreader are excessive, inserts (e.g., heat pipes, pyrolytic graphite inserts) having high effective thermal conductivities may be integrated with/into the heat spreader to offer/provide improved thermal paths. [0146] Because of their structural properties, metal heat spreaders may be rigid (e.g., mechanically inflexible). Due to tolerance uncertainties which may be associated with an assembly that includes a heat spreader, a chassis, and a circuit board, the heat spreader of said assembly may be designed for some tolerance stack-up in order to prevent subjecting an electronics component (which may be connected to the circuit board) to forces which may be generated by a tight or interference fit between the heat spreader and the electronics component. Alternatively, a non-metal heat spreader may be implemented and may provide improved mechanical flexibility compared to a metal heat spreader. However, a non-metal heat spreader may have an extremely low thermal conductivity relative to a metal heat spreader, and thus, may not be a suitable option. [0147] The rigid, metal heat spreader may also be implemented with a compliant thermal gap filler/thermal interface material. The thermal interface material may be placed between the metal heat spreader and an electronics component to ensure that a non-air conduction path exists between a surface of the metal heat spreader and a surface of the electronics component. The thermal interface material/compliant material may generally be organic- based and may have a thermal conductivity which may be approximately two orders of magnitude lower than the thermal conductivity of the metal of the metal heat spreader. Thus, the thermal interface material may contribute a significant portion of an overall thermal resistance path between the electronics component and an ambient environment. [0148] A number of basic metals which may be used in metal heat spreaders may have thermal conductivities of about 100-400 Watts/meters • Kelvin (W/mK). Heat pipes and exotic materials, such as graphite and diamond, which may be integrated with heat spreaders may exhibit effective thermal conductivities of up to approximately ten times greater than 100-400 (W/mK). As power dissipation from electronic components continues to increase, it may be desirable to construct heat spreaders/to implement thermal spreading technologies which provide higher effective thermal conductivities. However, the suitability for use of certain materials when constructing heat spreaders/implementing thermal spreading technologies may be limited by factors such as heat flux limits (e.g., for heat pipes), orthotropic properties (e.g., of graphite), or cost (e.g., of diamond). Therefore, it may be desirable to implement a heat spreader technology which produces/provides a heat spreader that is: a.) mechanically flexible; b) has an effective thermal conductivity which is significantly higher than the effective thermal conductivities of currently available rigid, metal heat spreaders or heat pipe assemblies; and c.) has heat flux limits which are significantly higher than the heat flux limits of currently available rigid, metal heat spreaders or heat pipe assemblies.

[0149] Referring generally to FIGS. 12-15, a heat spreader/thermal spreader in accordance with an exemplary embodiment is shown. The thermal spreader 100 may include a mechanically flexible substrate 102. In exemplary embodiments, the substrate 102 may be at least partially (e.g., primarily) constructed/fabricated of flexible or mechanically compliant materials. For example, the substrate 102 may be at least partially constructed of organic materials. Further, the substrate 102 may be at least partially constructed of organic-inorganic composite materials which may include glass, ceramics, carbon, metal reinforcements, thin metallic sheets, molded plastic materials, standard circuit board materials, flexible circuit board materials, rigid-flex circuit cards, and/or the like. Constructing the substrate 102 at least partially of organic materials (rather than constructing a thermal spreader entirely of metal) may provide a thermal spreader 100 which is mechanically flexible, lightweight and low cost.

[0150] As described above, because the mechanically flexible substrate 102 of thermal spreader 100 is made of/includes regions of a compliant material, it may be sufficiently flexible so that it may bend and thereby make up much if not all of any dimensional gaps between a heat source/heat source region and a heat sink/heat sink region due to tolerance stack-up, thermal expansion effects, vibration, etc. For instance, the substrate 102 of the thermal spreader 100 may be configured to bend to a sufficient degree such that it may contact two or more surfaces that have a varying mechanical separation in a direction perpendicular to a plane of the substrate 102 due to tolerance stackup, vibration, thermal expansion, etc. Such flexibility of the substrate 102 of the thermal spreader 100 may promote a reduced need for utilizing compliant thermal gap filling materials (e.g., thermal pads, gels) that may otherwise be needed to provide compliance, said compliant thermal gap filling materials also typically representing a significant thermal resistance. [0151] In further embodiments, the mechanically flexible substrate 102 may form at least one internal channel/flow channel 104. The internal channel 104 may be configured for containing a liquid which may in some embodiments be an electrically-conductive liquid. In exemplary embodiments, the internal channel 104 may provide for/may allow closed- loop flow of the electrically-conductive liquid (e.g., the internal channel 104 may be/may include an internal/embedded cooling loop). In exemplary embodiments, the electrically- conductive liquid may be/may include a liquid metal and/or a liquid metal alloy. For example, the liquid metal alloy may include at least two of the following: Gallium, Indium, Tin, Zinc, Lead and Bismuth. For instance, the liquid metal alloy may be a Gallium- Indium-Tin eutectic known as Galinstan. In further embodiments, the electrically- conductive liquid may include a metal having a melting temperature of less than fifty (50) degrees Celsius. In additional embodiments, the substrate 102 may include one or more mechanically compliant layers, such as a first mechanically compliant layer 106 and a second mechanically compliant layer 108. Further, the internal channel/internal cooling loop 104 may be formed by/formed between/embedded between the first compliant layer 106 and the second compliant layer 108. [0152] In current embodiments, the thermal spreader 100 may further include a mechanism for circulating the electrically-conductive liquid/fluid, such as at least one pump 110. The pump 110 may be configured for being connected to/integrated with the substrate 102. The pump 110 may be further configured for circulating the flow of/moving the electrically-conductive liquid within the internal channel 104 so that the thermal spreader 100 may provide a high effective thermal conductivity between heat source(s) (e.g., electronics component(s) on a circuit board) to which the thermal spreader 100 may be connected/attached, and heat sink(s) (e.g., a chassis/chassis rail(s) in/on which the electronics component/circuit board may be mounted) to which the thermal spreader 100 may be connected/attached. In this way, the thermal spreader 100 may be configured for directing thermal energy from the heat source to the heat sink via the electrically-conductive liquid. In exemplary embodiments, the pump 110 may be a piezoelectric positive displacement pump, an inductive pump, a magnetic pump (e.g., a solid state magnetic pump), or the like.

[0153] In further embodiments, the thermal spreader 100 may include one or more localized, high thermal conductivity/thermally-conductive, rigid metal inserts 112. Each insert 112 may be configured for being connected to/integrated with/received by (e.g., such as via slots formed by the substrate)/p laced within the mechanically flexible substrate 102 such that the insert 112 may be in thermal contact with the electrically-conductive liquid and the substrate 102. Further, each insert 112 may be further configured for promoting heat transfer between the thermal spreader 100 and the electrically-conductive liquid (e.g., for promoting thermal energy transfer/local heat transfer to/into and from/out of the electrically-conductive liquid/coolant). In additional embodiments, each insert 112 may include a first surface 114 and a second surface 116, the first surface 114 being located generally opposite the second surface 116. The first surface/internal surface 114 may be configured for being oriented toward the internal channel 104 (e.g., oriented so as to physically contact the electrically-conductive liquid). The second surface/external surface 116 may be configured for being oriented away from the internal channel 104 (e.g., oriented so as to not physically contact the liquid).

[0154] In current embodiments, the first surface 114 of each insert 112 may be configured with one or more mechanical features/fine features/roughened areas/machined areas/extended surfaces/extension portions 118. The extension portions 118 may promote heat transfer between the insert 112 and the electrically-conductive liquid by providing increased or additional contact surface area/thermal contact area/convective heat transfer area, thereby reducing convective thermal resistance between the insert 112 and the liquid. The insert 112 may be fabricated with the extension portions 118 via manufacturing processes, such as machining, extrusion, chemical etching, or the like. For instance, the extension portions 118 may be fins, pins, or plates which may be aligned with a direction of flow of the liquid, or said extension portions 118 may be other suitable geometries for increasing the heat transfer area of the insert 112 and/or for creating localized turbulence to provide higher levels of heat transfer. The fine features/roughened areas/extension portions 118 may be produced via machining, roughening, machining extrusion, chemical etching, molding, or other like processes. Further, the extension portions 118 of the inserts 112 may allow the inserts 112 to provide structural support for the compliant layers (106, 108) of the mechanically flexible substrate 102, said compliant layers (106, 108) sandwiching or being positioned on each side of (e.g., above and below) the internal channel 104. In still further embodiments, the second surface/external surface 116 of the insert 112 may be smooth for promoting minimization of contact resistance.

[0155] In further embodiments, each insert 112 may be at least partially constructed of/may be integrated with thermally-conductive foam, an array of carbon nanotubes, high thermal-conductivity filaments, and/or the like, for providing additional heat transfer surfaces/thermal enhancements for the thermal spreader 100. For example, the thermally- conductive foam may be a graphite foam, a graphite alloy foam, and/or a copper alloy foam. [0156] When implementing/during application of electrically conductive liquid cooling (such as via the internal channel 104/cooling loop described above), a possible limiting issue may be the potential for chemical/metallurgical interactions between metals of/within the thermal spreader 100 and the liquid. In order to maximize thermal performance of the thermal spreader 100, it may be imperative that the electrically-conductive liquid have good thermal contact with the metal inserts 112 of/within the thermal spreader 100. However, metallurgical or chemical interactions between metal(s) of the thermal spreader 100 (e.g., metals of the substrate 102 and/or the inserts 112) and the electrically-conductive liquid may lead to corrosion of said metal(s) of the thermal spreader 100 into the liquid, which may result in changes in the properties of the liquid. If the liquid is a metal alloy, additional metals which corrode into the liquid may result in the formation of a new metal alloy in the liquid. This new metal alloy may be highly corrosive and/or may have a higher melting temperature metal. For example, when Gallium-containing alloys are brought into contact with Aluminum, the Gallium may rapidly diffuse into the Aluminum, thereby resulting in the formation of a highly corrosive alloy, particularly when in the presence of moisture. Further, Gallium, Indium and Tin may tend to have high diffusion coefficients into metals such as Gold, Copper, and Silver, which may result in the production of higher melting temperature alloys upon diffusion and alloy formation.

[0157] A possible solution to the above-referenced problem may involve applying/plating Nickel to the thermal spreader 100 (e.g., to the metal inserts 112 of the thermal spreader 100) to protect the thermal spreader 100 from corrosion. However, this solution may be expensive, the Nickel may represent a thermal resistance, and the Nickel may still react with the liquid. A further possible solution may involve evaporation/sputtering/chemical vapor deposition/plating of materials such as Tantalum, Tungsten, other inorganic coatings, and/or organic coatings (e.g., Parylene) onto the thermal spreader 100 via a vapor deposition process(es). Although application of such materials may provide a suitable barrier, said vapor deposition processes using said materials may be expensive and/or complicated to perform. The present invention addresses the above-referenced problem by providing a thermal spreader 100 which may have a protective barrier between the electrically- conductive liquid and metal surfaces of the thermal spreader 100 (e.g., metal portions of the flexible substrate which may contact/may otherwise contact said liquid, the surfaces of the metal inserts 112 which may contact/may otherwise contact said liquid). Further, the protective barrier/coating provided by the present invention may be a non-metallic coating (e.g., alkali silicate glass) that is extremely thin, provides minimal thermal resistance, while providing superior long term protection/preventing electrochemical reactions between metal surfaces of the thermal spreader 100 and the electrically-conductive liquid. [0158] In exemplary embodiments, the first surface/internal surface 114 (e.g., the surface oriented toward/more proximal to/so as to contact the liquid) of each insert 112 may be at least partially coated with one or more layers of a protective coating, such as alkali silicate glass. For example, a layer included in the one or more layers of alkali silicate glass may have a thickness value ranging between and including the values of 0.1 microns and 10.0 microns. In additional embodiments, other surfaces/portions of the thermal spreader 100 (e.g., fine features on the interior/first surface 114 of each insert 112, such as the extension portions 118, which may be configured for being positioned/located at heat source and heat sink locations) may also be at least partially coated with the protective alkali silicate glass coating. The alkali silicate glass may have one or more of a number of various compositions, including but not limited to those compositions described in United States Patent Application No. 11/732,982, filed on April 5, 2007, entitled: "A Method For Providing Near-Hermetically Coated Integrated Circuit Assemblies"; United States Patent Application No. 11/508,782, filed on August 23, 2006, entitled: "Integrated Circuit Protection and Ruggedization Coatings and Methods"; and/or United States Patent Application No. 12/116,126, filed on May 6, 2008, entitled: "System and Method for a Substrate with Internal Pumped Liquid Metal for Thermal Spreading and Cooling", which are herein incorporated by reference.

[0159] In exemplary embodiments, the alkali silicate glass (ASG) layers may be easily deposited implementing standard atmosphere/near room temperature processes, thereby allowing for low recurring cost/low capital investment processing methods. For instance, the alkali silicate glass may be applied by spraying one or more layers of the material/ASG onto the thermal spreader 100 via an Asymtek® jetting system and an appropriate spray head. Alternatively, the alkali silicate glass coating may be applied by flooding the internal channel(s) 104 with a solution of the ASG coating and then utilizing forced air to remove any excess ASG coating/solution. In further embodiments, appropriately passivated electrodes (e.g., electrodes coated with/constructed entirely of a passivation metal such as Tungsten, Tantalum, or Nickel) may be inserted into/integrated with the mechanically flexible substrate 102 post-treatment (e.g., after the ASG coating is applied). Still further, the electrodes may be constructed of graphite or another properly coated metal, such as Tantalum, Tungsten, or Nickel. The electrodes may be configured for generating an electrical current flow through the electrically-conductive liquid via an applied voltage to said electrodes. In further embodiments, the thermal spreader 100/surfaces of the thermal spreader which may contact the electrically-conductive liquid may be at least partially coated with a substance which may improve wetting characteristics for the liquid. [0160] As mentioned above, the thermal spreader 100 may be configured for providing a high effective thermal conductivity between a heat source and a heat sink. The thermal spreader 100 may be implemented in a variety of applications. For example, the thermal spreader 100 of the present invention may be implemented as part of a thermal spreader assembly 300 as shown in FIG. 16. In exemplary embodiments, the thermal spreader assembly 300 may include a heat source, such as a conduction-cooled circuit card assembly 302. The conduction-cooled circuit card assembly 302 may include a circuit card 304. The circuit card assembly 302 may further include an electronic component 306 mounted on the circuit card 304. The circuit card assembly 302 may further include a plurality of mechanical mounting fixtures (e.g., wedge locks, card guides, etc.) 308 mounted on said circuit card 304. The thermal spreader assembly 300 may further include a thermal spreader 100 as described above. The thermal spreader 100 may be configured for being thermally connected to the circuit card 304 and the electronic component 306, such as via a layer of thermal adhesive 310. The thermal spreader 100 may be further configured for being thermally connected to a heat sink, such as a chassis/electronics housing, by being mounted in the chassis (e.g., on rails of the chassis) via the mechanical mounting fixtures/mounting feature(s) 308. The thermal spreader 100 is configured for providing thermal conductivity between the heat source (e.g., the electronic component 306) and the heat sink (e.g., the chassis). The mechanical compliance of the thermal spreader 100 of the present invention may allow for a thermal spreader assembly 300 which has a reduced need for thermal gap filler, is lighter weight and lower in cost than thermal spreader assemblies which implement a mechanically rigid thermal spreader (e.g., a thermal spreader constructed entirely of metal).

[0161] FIG. 17 illustrates a method for fabricating/producing/providing a thermal spreader in accordance with an exemplary embodiment. The method 400 may include the step of fabricating a mechanically flexible substrate 402. As mentioned above, at least a portion of the mechanically flexible substrate may be constructed of organic material. The method 400 may further include the step of providing an internal channel within the mechanically flexible substrate 403. The internal channel may be configured for containing an electrically-conductive liquid and may be further configured to allow for closed-loop flow of the electrically-conductive liquid within the internal channel. For example, the internal channel may be provided by forming the internal channel within the mechanically flexible substrate (e.g., the internal channel may be a recess/groove/slotted recess formed within the mechanically flexible substrate, as shown in FIG. 18) or by integrating the internal channel/flow loop within the mechanically flexible substrate (e.g., the flow loop/internal channel may be a separate component connected to/integrated within/received within/accommodated by the mechanically flexible substrate). The method 400 may further include the step of integrating a pump with the mechanically flexible substrate 404. For example, as described above, the pump may be configured for circulating the electrically- conductive liquid within the internal channel. [0162] The method 400 may further include the step of fabricating a plurality of rigid metal inserts 406. For instance, as discussed above, each rigid metal insert may be configured for being integrated with the mechanically flexible substrate for promoting the transfer of thermal energy both to and from the electrically conductive liquid. As described above, the thermal spreader is configured for being connected to a heat source and a heat sink, and is further configured for directing thermal energy from the heat source to the heat sink via the electrically-conductive liquid. The method 400 may further include the step of forming a plurality of extension portions on a surface of each rigid metal insert included in the plurality of rigid metal inserts 408. For instance, as described above, said extension portions may be configured for promoting thermal energy transfer between the rigid metal insert and the electrically-conductive liquid. The method 400 may further include the step of connecting the plurality of rigid metal inserts to the mechanically flexible substrate 410. [0163] The method 400 may further include the step of coating a metal portion of an electrically-conductive liquid contact surface of the mechanically flexible substrate with a layer of alkali silicate glass 412. The method 400 may further include the step of coating an electrically-conductive liquid contact surface of each rigid metal insert with a layer of alkali silicate glass 414. The method 400 may further include the step of integrating a plurality of passivation metal-coated electrodes with the mechanically flexible substrate 416. As discussed above, said electrodes may be configured for generating an electrical current flow through an electrically-conductive liquid via an applied voltage to said electrodes. [0164] As discussed above, thermal spreaders may be used for diffusing thermal energy from heat sources and for transporting the thermal energy to a location at which the thermal energy (e.g., heat) may be dissipated. For instance, the thermal spreader may be used in electronics to remove heat from a high power electronic component which may be connected to a circuit board, and to conduct said heat/thermal energy to the walls of a chassis in which the circuit board/circuit card is mounted/enclosed. A number of thermal spreaders may be custom-designed/fabricated for use with a particular circuit card assembly and/or may utilize thermal gap filler for providing a thermal path between a power- dissipating component on a circuit card assembly and the thermal spreader. Further, as previously discussed, a number of thermal spreaders may be made of metals and may be expensive to produce due to: a.) high energy costs associated with processing the metals; b.) the processing time required for machined parts; and/or c.) the tooling costs for providing cast or extruded thermal spreaders. [0165] In contrast to metal thermal spreaders (which utilize conduction) or thermal spreaders implementing heat pipes (which utilize a vapor pressure/capillary force-driven fluid flow), the thermal spreader 100 utilizes a pumped, electrically-conductive liquid for transporting thermal energy. The thermal spreader 100 implements an approach which may serve to separate the thermal transport mechanism from the structure/structural mechanism, thereby providing good thermal conduction even though the mechanically flexible thermal spreader 100 may be constructed of organic (e.g., mechanically flexible) materials. [0166] Referring generally to FIGS. 18-19, a thermal spreader 500 in accordance with a further exemplary embodiment is shown. The thermal spreader 500 may include a mechanically flexible substrate 502. The mechanically flexible substrate 502 may be formed of/may include multiple layer portions. For example, the substrate 502 may be constructed as a 3-layer portion configuration in which a middle/second layer portion 504, which forms/includes an internal channel 506 for containing electrically-conductive liquid, is "sandwiched" between a top/first layer portion 508 and a bottom/third layer portion 510. In additional embodiments, the bottom layer portion 510 may form a plurality of recesses 512 (e.g., slots) configured for allowing the bottom layer portion 510 to integrate with (e.g., receive) a plurality of metallic, high thermal conductivity inserts 514. Said inserts 514 may be configured for providing localized higher heat flux at heat source and/or heat sink locations. In still further embodiments, one or more of the layers (504, 508, 510) may be constructed of organic materials, inorganic materials, or the like for providing the mechanically flexible substrate 502, which may be a low-profile/thin substrate. For instance, said materials may include standard circuit board materials, rigid-flex materials, and/or the like.

[0167] Referring to FIG. 20, a method for providing/fabricating/producing said thermal spreader 500 is shown. In an exemplary embodiment, the method 600 may include the step of laminating the plurality of layer portions together to fabricate the mechanically flexible substrate 602. As mentioned above, the mechanically flexible substrate may be at least partially constructed of thin, organic material. The method 600 may further include the step of providing an internal channel within the mechanically flexible substrate 603. The internal channel may be configured for containing an electrically-conductive liquid and may be further configured to allow for closed-loop flow of the electrically-conductive liquid within the internal channel. The method 600 may further include the step of integrating a pump with the mechanically flexible substrate 604. For example, as described above, the pump may be configured for circulating the electrically-conductive liquid within the internal channel.

[0168] The method 600 may further include the step of fabricating a plurality of rigid metal inserts 606. For instance, as discussed above, each rigid metal insert may be configured for being integrated with the mechanically flexible substrate for promoting the transfer of thermal energy both to and from the electrically conductive liquid. As described above, the thermal spreader is configured for being connected to a heat source and a heat sink, and is further configured for directing thermal energy from the heat source to the heat sink via the electrically-conductive liquid. The method 600 may further include the step of forming a plurality of extension portions on a surface of each rigid metal insert included in the plurality of rigid metal inserts 608. For instance, as described above, said extension portions may be configured for promoting thermal energy transfer between the rigid metal insert and the electrically-conductive liquid.

[0169] The method 600 may further include the step of connecting the plurality of rigid metal inserts to the mechanically flexible substrate 610. For example, as discussed above, the inserts may be received by/connected to the substrate via recesses formed by the substrate. The method 600 may further include the step of coating a metal portion of an electrically-conductive liquid contact surface of the mechanically flexible substrate with a layer of alkali silicate glass 612. The method 600 may further include the step of coating an electrically-conductive liquid contact surface of each rigid metal insert included in the plurality of rigid metal inserts with a layer of alkali silicate glass 614. The method 600 may further include the step of integrating a plurality of passivation metal-coated electrodes with the mechanically flexible substrate 616. As discussed above, said electrodes may be configured for generating an electrical current flow through an electrically-conductive liquid via an applied voltage to said electrodes.

[0170] Referring to FIG. 21, a method 700 for providing/fabricating/producing a plurality of thermal spreaders 500 via additive manufacturing/built-up processing/sequential addition processing/parallel processing/batch processing is shown. In an exemplary embodiment, the method 700 may include the step of laminating a plurality of layer sheets together to fabricate a mechanically flexible substrate sheet 702. For example, as shown in FIG. 22, a first layer sheet 802, which may include a plurality of top/first layer portions 508, a second layer sheet 804, which may include a plurality of middle/second layer portions 504, and a third layer sheet 806, which may include a plurality of bottom/third layer portions 510 may be laminated together to fabricate a mechanically flexible substrate sheet 800. For instance, fabrication of the mechanically flexible substrate sheet may be performed using conventional circuit board manufacturing processes. In further embodiments, the method 700 may further include the step of dicing the mechanically flexible substrate sheet to form a plurality of mechanically flexible substrates 704. As mentioned above, each mechanically flexible substrate may be at least partially constructed of a range of thin, organic materials. The mechanically flexible substrate may also be partially constructed of inorganic materials. The method 700 may further include providing an internal channel within each mechanically flexible substrate included in the plurality of mechanically flexible substrates 705. For example, each internal channel may be configured for containing an electrically- conductive liquid and may be further configured to allow for closed- loop flow of the electrically-conductive liquid within the internal channel.

[0171] In additional embodiments, the method 700 may further include the step of integrating a pump with each mechanically flexible substrate included in the plurality of mechanically flexible substrates to form a plurality of thermal spreaders 706. For example, each individual mechanically flexible substrate may be integrated with its own corresponding pump to form a thermal spreader. Still further, the method 700 may further include the step of fabricating a plurality of rigid metal inserts 708. The method 700 may further include the step of forming a plurality of extension portions on a surface of each rigid metal insert included in the plurality of rigid metal inserts 710. The method 700 may further include the step of connecting the plurality of rigid metal inserts to the plurality of mechanically flexible substrates 712.

[0172] In exemplary embodiments, the method 700 may further include the step of coating a metal portion of electrically-conductive liquid contacting surfaces of each mechanically flexible substrate included in the plurality of mechanically flexible substrates with a layer of alkali silicate glass 714. The method 700 may further include the step of coating an electrically-conductive liquid contacting surface of each rigid metal insert included in the plurality of rigid metal inserts with a layer of alkali silicate glass 716. The method 700 may further include the step of integrating a plurality of passivation metal- coated electrodes with each mechanically flexible substrate included in the plurality of mechanically flexible substrates 718. In this way, manufacture of the plurality of thermal spreaders may be performed via a low cost, batch processing methodology, utilizing low cost materials. Further said thermal spreaders produced via such methods may be lightweight and suitable for use in weight and size conscious applications, such as airborne electronics and portable consumer electronics (such as laptop computers). [0173] Localized forced convection cooling may be applied for thermal management of electronics. For example, a computer may implement one or more fans for cooling purposes. However the moving parts of the fans may be potential weak links with regards to overall system reliability. Solid-state pumps may be used in liquid cooled systems which demand very high reliability. For instance, one method of solid-state pumping may involve application of a magnetic field in combination with an electric current for applying a pumping force to the liquid/fluid of the liquid cooled system. This magnetic pumping method may require that said liquid have a high electrical conductivity, so liquid metal or any other liquid with sufficiently high electrical conductivity may be implemented. The present invention provides a solid-state mechanism for pumping electrically conductive liquids within a thin, mechanically flexible thermal spreader.

[0174] As described above, a magnetic pump, such as a solid-state magnetic pump may be implemented for circulating electrically-conductive liquid within the mechanically flexible substrate of the thermal spreader. Referring generally to FIGS. 23-25, an exemplary embodiment of a thermal spreader 900 is shown which includes/implements a magnetic pump 110. As previously discussed, the thermal spreader 900 may be a thin, mechanically flexible thermal spreader which includes/forms an electrically conductive liquid cooling loop/internal channel 104. Further, the thermal spreader 900 may be configured with embedded electrodes 902. A voltage may be applied across the electrodes 902 for generating a current flow through an electrically conductive liquid. [0175] In current embodiments of the present invention, the thermal spreader 900/pump 110 may be configured with one or more magnets 904. Further, the pump 110 may include a casing, which may, for instance, be constructed of ferrous material (e.g., a ferrous lens 906). Each magnet 904 may be connected to/integrated with/enclosed within/encased by the ferrous lens 906. In exemplary embodiments, when the pump 110 is connected to the mechanically flexible substrate 908 of the thermal spreader 900, the magnets 904 may be positioned/located on opposite sides of the internal channel 104 (as shown in FIG. 24). The ferrous lens 906 is configured for maximizing the pumping power of the pump 110 and for focusing magnetic flux. The pump 110 further provides a low profile liquid pumping mechanism which may be added/connected to/integrated with the mechanically flexible substrate 908/thermal spreader 900, while still allowing the thermal spreader 900 to remain mechanically flexible. FIG. 26 illustrates that the thermal spreader 900/mechanically flexible substrate 908 may include/may form a slotted portion 910 for allowing the pump 110 to be connected to/received by the thermal spreader 900 and for allowing the ferrous lens 906 to pass through/be received so that said ferrous lens may fully contain a magnetic field generated within the thermal spreader 900.

[0176] In further embodiments, the pump 110 may be configured for being integrated with a rigid metal insert 912 to form a magnetic pump assembly/pump-rigid metal insert assembly 914, as shown in FIGS. 27-28. In an exemplary embodiment, a thermal spreader 1100 may be provided which includes the pump-rigid metal insert assembly 914. For instance, the pump-rigid metal insert assembly 914 may be configured for being connected to a mechanically flexible substrate 1102 of the thermal spreader. The substrate 1102 may include/form a slotted portion 1104 (as shown in FIG. 29) for receiving/connecting with the pump-rigid metal insert assembly 914. The rigid metal insert 912 may be configured for promoting heat transfer between the thermal spreader 1100 and the electrically-conductive liquid (e.g., for promoting thermal energy transfer/local heat transfer to/into and from/out of the electrically-conductive liquid/coolant). Further, the pump 110 may be constructed of a thermally conductive material (e.g., metal) which may, in combination with the metal of the insert 912, allow for the pump-rigid metal insert assembly 914 to provide thermal conduction/thermal spreading properties to the thermal spreader 1100. The ferrous lens 906 may form/may include one or more vias 916 which may be at least partially filled with a thermally-conductive material for promoting increased local thermal conductivity of the pump-rigid metal insert assembly 914.

[0177] When implementing a magnetic pump with an electrically-conductive cooling loop, a current path (generated via the electrodes) through the moving liquid in a uniform or non-uniform magnetic field may be an arc, rather than following a straight line. If the arc bridges outside of the magnetic field, the efficiency of the pump may be significantly reduced, which may result in lower fluid flow rates and/or pressure head. As the magnetic pump is miniaturized, the effects of the non-uniform magnetic field may become more significant.

[0178] For the pump 110, the force induced on the electrically-conductive liquid may be due to current flowing through the liquid between the electrodes 902. The effective electrical impedance of the electrically-conductive liquid may be a function of the applied magnetic field. In an ideal system, a constrained, straight-line current path in a uniform magnetic field resulting in a uniform force on the liquid metal across the internal channel 104 would occur, as shown in FIG. 30. However, in practice, the magnetic field (and therefore the impedance) may generally not be uniform and the current path may generally not be a straight line due to the continuous force on the electrons normal to the direction of the current. Variation in magnetic flux across the internal channel 104/pump channel may also contribute to the deviation in current path and subsequent pump head pressure non- uniformity. In a system, considering/assuming a uniform magnetic field is applied, the current path may generally flow in an arc rather than a straight line. Under worst case conditions, current flow may occur at regions beyond the magnetic field and may thus produce reduced pumping force on the liquid/fluid, as shown in FIG. 31. The effect of such arcing/curvature of the electric current may become more significant (particularly in the direction of the liquid flow) as the pump is miniaturized. If the pump 110 is integrated into a flexible thermal spreader, as described above, the need to maintain a short/small profile pump may be significant for maintaining the overall flexibility of the thermal spreader. [0179] Referring to FIG. 32, a magnetic pump 1400 for circulating electrically-conductive liquid within an internal flow channel/electrically conductive cooling loop 104, in accordance with a further exemplary embodiment, is shown. In the illustrated embodiment, the magnetic pump 1400 (e.g., a casing of the magnetic pump, such as the ferrous casing described above) may include/form an input port 1402 and an output port 1404. As described above, the magnetic pump 1400 may be connected to a mechanically flexible substrate 102 of a thermal spreader 100. Further, the mechanically flexible substrate may form an internal channel 104 within which electrically-conductive liquid may circulate/flow for promoting cooling properties of the thermal spreader 100. The magnetic pump 1400 may be configured for applying a magnetic field to electrically-conductive liquid within the internal channel 104 for providing pumping force to the liquid. Said magnetic force is applied via magnets 904 enclosed within the ferrous lens 906 of the pump 1400. [0180] In the illustrated embodiment, the magnetic pump 1400/magnetic pump casing may include/may form a plurality of flow channels 1406. The flow channels 1406 may be configured/formed proximal to the output port 1404 of the pump. The magnetic pump 1400/magnetic pump casing may be further configured with channel walls 1408 for separating the flow channels 1406. The flow channels/dielectric flow straightener channels 1406 may be configured for allowing the electrically-conductive liquid within the internal channel to flow through the pump 1400 (e.g., the liquid may flow from/into the input port 1402 and past/through the output port 1404 of the pump 1400) in the direction of flow of the liquid. However, the channel walls 1408 may be configured for being non-electrically conductive, and thus, may further be configured for preventing current flow in a direction generally perpendicular to the direction of the flow of the liquid, thereby promoting increased or maximized pumping power/pumping efficiency for the pump 1400. Further, the pump 1400 described in the embodiment above, by inhibiting current flow in regions of lower magnetic flux, may be easily miniaturized for allowing said pump 1400 to be implemented in a thermal spreader 100 as described above in such a manner that allows the flexibility of said mechanically flexible thermal spreader 100 to be maintained. [0181] Power/heat/thermal energy dissipated by electronics and other systems, such as internal combustion engines, may be transported from the heat source to a location where said heat may be transferred to the environment. Said transport of heat may occur via a thermal path, such as by conduction (e.g., via solid materials), or by convection, to fluids/liquids which travel between heat dissipating and heat absorbing surfaces. Issues such as mechanical tolerance stack-up, maintenance requirements, the need for vibration isolation, etc., may make it generally difficult to utilize a completely rigid system for said thermal path. However, a number of compliant mechanisms for providing said thermal path may have less than desirable/low thermal transport properties. The present disclosure describes a flexible thermal path which may allow two bodies (e.g., heat source and heat sink) to remain in good thermal contact without being mechanically affixed to each other. [0182] As discussed above, an electrically conductive liquid cooling loop may be formed/embedded/included within a mechanically flexible substrate. Also discussed above was the idea of integrating metallic inserts with/within the substrate at regions of high heat flux into or out of the substrate for minimizing overall thermal resistance. [0183] Referring generally to FIGS. 33-36, a flexible liquid cooling loop for providing a thermal path between a heat source surface and heat sink surface in accordance with an exemplary embodiment is shown. In the illustrated embodiment, the flexible cooling loop 1500 includes a plurality of mechanically rigid tubing sections 1502 (e.g., short, generally rectangular cross-section tubing sections, as shown in FIG. 34). The flexible cooling loop 1500 further includes a plurality of mechanically flexible tubing sections 1504. The mechanically rigid tubing sections 1502 may be connected by/held together by the mechanically flexible tubing sections 1504 (e.g., mechanically compliant couplings) to form the loop 1500. The loop 1500 may be configured for containing a liquid (e.g., an electrically-conductive liquid) which may be circulated within the loop 1500 for promoting the transfer of thermal energy (e.g., heat) from a heat source surface 1506 (e.g., a heat dissipating surface/hot surface) to a heat sink surface 1508 (e.g., a heat absorbing surface/cool surface) via the loop 1500.

[0184] In further embodiments, as shown in FIG. 35, one or more of the mechanically rigid tubing sections 1502 may be configured for contacting/being directed against/the heat source surface 1506 during implementation of the loop 1500. Also, one or more of the mechanically flexible tubing sections 1504 may be configured for contacting/being directed against/the heat sink surface 1508 during implementation of the loop 1500, thereby allowing the loop 1500 to provide a thermal path for directing heat from the heat source 1506 to the heat sink 1508. For instance, the loop 1500 may be positioned/sandwiched between the heat source 1506 and the heat sink 1508. In exemplary embodiments, the rigid tubing sections 1502 of the loop 1500 may be constructed of a material which promotes improved heat transfer (e.g., metal) and/or may be constructed of a material which may provide a light/reduced weight loop (e.g., organic materials). In further embodiments, the flexible tubing sections 1504 may be constructed of flexible, rubber-like/elastomeric material(s). [0185] In additional embodiments, the loop 1500 may include one or more pumps 1510 (e.g., a solid-state magnetic pump). The pump 1510 may be configured for being connected to/integrated within/integrated into the loop via the mechanically flexible couplings 1504. The pump 1504 may be further configured for circulating the liquid within the loop 1500 for promoting transfer of heat from the heat source 1506 to the heat sink 1508 via the loop 1500. In embodiments in which the pump 1510 is included in/as part of the loop 1500, the liquid in the loop may not be required to be electrically conductive. The pump(s)/individual pump sections 1510 may be easily fabricated and tested prior to being assembled into the rest of the loop 1500.

[0186] The loop 1500 of the present invention may be conformable to non-smooth heat sink/heat source surfaces. Consequently, the loop 1500 of the present invention may be less sensitive to roughness or debris of heat sink/heat source surfaces, than would be the case if, for instance, the loop-heat source surface interface were a solid-solid interface over the entire heat transfer area (e.g., an interface in which said loop was not conformable to the heat source surface).

[0187] In exemplary embodiments, the loop 1500 may further include one or more thermoelectric generators/thermoelectric modules 1512 (as shown in FIG. 36). The module(s) 1512 may be integrated into the loop 1500/connected via the flexible tubing sections 1504 at one or more locations/points at which heat is transferred into/out of the liquid cooling loop 1500. The modules 1512 may be configured for "tapping" into part of the flow of heat into/out of the loop for generating electrical power and providing said electrical power to the pump(s) 1510 for driving the pump(s) 1510 to produce a net-passive device. The loop 1500 of the present invention provides an inherently parallel thermal path configuration which promotes the prevention of impeded thermal transfer to/from the loop 1500, for instance, when said generator/module 1512 is implemented in the loop 1500. [0188] The flexible liquid cooling loop 1500 may be implemented in/integrated within/embedded within thermal spreader. Further, the flexible liquid cooling loop 1500 may be implemented in/integrated within/embedded within a mechanically flexible substrate of a mechanically flexible, thin thermal spreader, such as one or more of the thermal spreader embodiments described above.

[0189] In further exemplary embodiments, as shown in FIG. 37, the flexible cooling loop 1500 may be implemented for providing a thermal path from a heat dissipating system 1602 (e.g., an electronics system) to a mounting plate 1604 (e.g., a vehicle chassis, machinery, etc.). Further, a plurality of vibration isolators 1606 may be included in a connection between/for connecting said heat dissipating system 1602 and the mounting plate 1604. In the scenario shown in FIG. 16, the loop 1500 may provide the thermal path to the mounting plate 1604, while the heat dissipating system 1602 is protected from high vibration and/or dynamic shock induced motion of the mounting plate 1604.

[0190] Referring generally to FIGS. 38-41, the flexible liquid cooling loop 1500 may have a variety of configurations. For example, as shown in FIGS. 38-39, the loop 1500 (as illustrated in top (FIG. 38) and side (FIG. 39) views) may be "watchband"-style configuration, wherein said loop is conformable, for instance, similar to a metal watchband. Further, as shown in FIGS. 40-41, the loop 1500 (as illustrated in top (FIG. 40) and side (FIG. 41) views) may be a flat, "racetrack" configuration.

[0191] In alternative embodiments, the loop 1500 may be constructed as a single portion of mechanically flexible tubing connected through/connecting the plurality of mechanically rigid sections 1502, allowing for a unitary, mechanically flexible tubing construction rather than implementing the multiple, mechanically flexible tubing couplings 1504. [0192] Referring generally to FIGS. 42 (top view) and 43 (side view), a liquid cooling loop 1900 for providing a thermal path between a heat source surface and a heat sink surface in accordance with an alternative exemplary embodiment is shown. The loop 1900 may include a plurality of mechanically rigid tubing sections 1902. (e.g., generally rectangular hollow cross-sections, as shown in FIG. 44). Each mechanically rigid section 1902 may form a first compartment 1904 and a second compartment 1906. The loop 1900 may further include a plurality of mechanically flexible tubing sections 1908. The mechanically flexible tubing sections 1908 may connect the rigid sections 1902 to form the loop 1900. For example, a first set of the flexible tubing sections 1910 may connect the rigid sections 1902 by being (e.g., insertably) connected into the first compartments 1904 of the rigid sections 1902. Further, a second set of the flexible tubing sections 1912 may connect the rigid sections 1902 by being (e.g., insertably) connected into the second compartments 1906 of the rigid sections 1902. The compartmentalized construction of the rigid sections 1902 may prevent the first set of flexible sections 1910 and second set of flexible sections 1912 from coming into contact with each other, thereby segregating the liquid of the loop 1900.

[0193] A number of assembly methods may be implemented for producing the loop (1500, 1900) embodiments as described above. Individual sections may be fabricated. For example, the rigid sections (e.g., metal sections) 1502 may be constructed by cutting an extruded tube. The loop 1500 may then be assembled by connecting the individual rigid sections 1502 to the flexible sections/couplings 1504, for instance, via an adhesive. Alternatively, the loop 1500, 1900 may be constructed via additive manufacturing, such as via an Objet Connex 500 which may print both rigid and flexible materials in a built-up assembly.

[0194] Referring generally to FIG. 45, a mechanically flexible substrate 2000 in accordance with a further alternative embodiment is shown. In the illustrated embodiment, the mechanically flexible substrate 2000 may include/may form an internal channel 2002. For instance, the internal channel 2002 may be configured for containing electrically- conductive liquid. The substrate 2000 may be further configured with a wall 2004, said wall 2004 being configured within the internal channel 2002. The substrate 2000 may further include one or more flexible bladders 2006. The bladder 2006 may be connected to the wall 2004, such that said wall 2004 may direct liquid flowing within the channel 2002 towards the bladder 2006 as shown. The bladder 2006 may be connected to the substrate 2000, such that said bladder 2006 may be connected to an interior surface 2008 of the substrate 2000 (e.g., inside of the internal channel 2002, as shown in FIG. 46, or to an exterior surface 2010 of the substrate 2000 (e.g., outside of the internal channel 2002, as shown in FIG. 47). Said bladder 2006 may be configured to bulge, as the liquid flowing within the internal channel 2002 exerts force against the bladder, thereby allowing the substrate 2000 to account for changes in pressure due to stack-up height. [0195] In further exemplary embodiments, as shown in FIGS. 48-49, a mechanically flexible substrate 2200 may be configured with one or more mini/microchannels 2202. For example, mini/microchannels 2202 may be fabricated into or onto the substrate 2200 via permanent photoresists. In a further example, mini/microchannels 2202 (e.g., the channel layer(s)) may be fabricated via permanent film-based photoresists, in which thin film barriers 2204, 2206 may be applied to the flexible substrate 2200 above and below the channel via lamination), thereby providing an inexpensive way to form a simple or complex microchannel 2202. Further, a mechanically flexible substrate 2300 (e.g., the internal channel/microchannel) may be formed/constructed to minimize channel-to-chassis interconnect, as shown in FIG. 50.

[0196] Referring now to FIGS. 51-58B, various low processing temperature hermetic glass coatings for microelectronics packaging that are desirable for hermetically sealing the packaging as well as providing resistance to corrosion and high temperature are illustrated according to various exemplary embodiments. These glass coatings may be applied and cured at low temperatures, typically < 100⁰C and produce tightly adhering hermetic (water impermeable) coatings capable of withstanding very high temperatures, theoretically up to ~700°C. These glass coatings may be composed of alkali silicate glass with nanoparticle modifiers, including, but not limited to, nano calcium carbonate, nano zinc oxide and nano silicon dioxide. Aqueous alkali silicate composite solutions applied on or between surfaces of materials dry to form a tough, tightly adhering inorganic bond that exhibits many desirable characteristics. Additionally, these solutions can be mixed with high thermal conductivity particles, such as, but not limited to, diamond, aluminum nitride, beryllium oxide, or metals to produce high thermal conductivity coatings for heat spreading. [0197] Alkali silicates, in general, are economical, environmentally friendly chemicals which have been used to protect a variety of materials from the corrosive effects of water. These chemicals are classified as corrosion inhibitors because they can deposit protective silicate rich films, isolating materials from corrosive attack. Additionally, they raise the pH of water which can make it less corrosive to metals. Studies have shown that alkali silicates 2400 are reactive with cationic metals and metal surfaces 2402. This is the basis by which silicates inhibit corrosion, as illustrated in FIG. 51. Although alkali silicates 2400 have been used to protect materials 2402 from corrosion, alkali silicates 2400 have not been applied to protecting microelectronics, because in standard, off the shelf configuration, they may not cure appropriately and may not exhibit resultant properties which are desirable for protecting microelectronics in harsh environments.

[0198] Liquid alkali silicate solutions are commercially available in a variety of SiO2 / M2O ratios. Typically, ratios of 3.25 down to 1 can be obtained in aqueous or powder form. Highly siliceous liquid alkali silicate solutions tend to air dry rapidly, are the most refractory (high melting temperature), and are the most resistant to acids and corrosion. These silica rich liquid solutions tend to contain more water than the alkaline rich solutions (per similar viscosity), and thus undergo greater shrinkage while curing. Low ratio, alkaline rich solutions tend to have greater elasticity, lower brittleness, and less shrinkage but may exhibit poor corrosion resistance. These low ratio coatings also dry more slowly because their alkali content creates a greater affinity for water. Many chemically resistant cements and mortars are produced using high ratio (N ~ 3.25) alkali silicate solutions. In order for the silicate coatings to become impermeable and relatively insoluble, water must be completely removed. Air drying alone is usually not adequate for coatings which will be exposed to weather or high moisture environments. For these applications heat curing is often needed. Curing temperatures between 95 and 100⁰C are often sufficient for adequate dehydration.

[0199] It is desirable to use highly corrosion resistant coatings in microelectronics packaging. While off-the-shelf alkali silicate solutions applied and processed in an appropriate manner could potentially provide a temporary hermetic barrier for microelectronic devices, they may not hold up in harsh testing environments, such as those produced during Highly Accelerated Stress Testing (HAST). In order to produce highly corrosion resistant coatings, modifiers must be added to the base alkali silicate solutions. Studies have shown that adding colloidal silicon dioxide to liquid alkali silicates can produce coatings that are comparable to that of current chromium based passivation, as characterized by salt spray testing. The purpose of these coatings is to protect steel and other metals from environmental corrosion. While a broad range of alkali silicate compositions may be used, highly silica rich coatings (R> 3.25) are the most corrosion resistant. These high ratio solutions can be made by adding additional SiO2 to the base alkali silicate. However, these silica rich coatings often crack during the curing process. This cracking may be avoided by applying the appropriate solution mixure, thickness, and using an appropriate curing process, all of which may be application specific. Successful silicate rich coatings (R> 4) have been applied to the surfaces of silicon die and other inorganic substrates, which can be cured quickly, are crack free, and possess excellent adhesion strength and durability. These silica enhanced alkali silicate solutions provide improved corrosion resistance, but they can be made more corrosion resistant with the addition of calcium carbonate and or zinc oxide. Silicate solutions can react with calcium to form insoluble calcium-silicate compounds. Similarly, zinc oxide has been used to produce silicate coatings that are actually capable of shedding water. In order to achieve good mixing and dispersion, nano-sized particles of these constituents may be used in the coatings described herein. The large surface area per weight of the nanoparticles helps to maximize silicate glass modification for improved corrosion resistance of the composite. [0200] It has been shown that increasing the silicate ratio, for alkali silicate glass coatings, may lead to cracking in thick coatings.

[0201] In an exemplary lab test, a particular amount of cracking was observed in thick silica rich (R=3.22) coatings, whereas no or little cracking was seen in the alkali rich coatings. In the silica rich coating, delamination was observed around the periphery and significant cracking throughout. When this same solution is applied in the appropriate thickness, a much stronger, crack free, fast curable coating can be formed. Such coatings have been applied to copper clad PCB substrates, aluminum and copper metals, and silicon die. These coatings are thin (<2 microns), but can be applied in multiple layers to build up the thickness. It has been observed that even these very thin coatings can provide a rugged moisture barrier at high temperatures (> 45O⁰C). The corrosion protection of silicate coating applied to a copper clad PCB board has been demonstrated.

[0202] When compared with conventional silicon Room Temperature Vulcanizing (RTV) (polymer) coatings, very little oxidation protection is seen while the alkali silicate glass coating provided a hermetic seal.

[0203] In another exemplary embodiment, silica rich coatings may be applied to wire bonded dies. The purpose of the coatings is to prevent galvanic corrosion at the wire bond / pad interface, a primary failure mechanism in these devices. Preventing this galvanic corrosion leads to significantly greater reliability and can potentially eliminate the need for hermetic packaging. [0204] In an exemplary and non-limiting embodiment, the alkali silicate glass coated wire bond pads may be formed by applying alkali silicate solutions onto chip surfaces then quickly curing at 15O⁰C for 5 minutes. Multiple layers may be applied to each of the coated wire bonds. The result of the coating process has been exemplary shown that the shear strength of coated joints were up to a 25% stronger than uncoated joints. Additionally, pull testing has shown no ball lifts (i.e. there were no separations between ball and pad) in the testing environment.

[0205] In addition to thin coatings, composites may be made by mixing the silicate solutions with high thermal conductivity particles such as aluminum nitride, beryllium oxide, diamond, and or metals. These coatings have been found to significantly improve heat transfer when coated over power dissipating devices. For example, thermal improvements in these coated devices are shown in FIG. 52.

[0206] Referring to FIG. 52, alkali silicate glass composites 2404 have been applied over power dissipating devices mounted on both laminate and copper metal substrates. The resulting package temperatures were reduced by more than 50%, while standard encapsulants 2406 caused device temperatures to increase up to 130%. [0207] In a further exemplary embodiment, the addition of nanoparticles to the alkali silicate glass thermal composites 2404 provides additional corrosion resistance. [0208] In accordance with exemplary embodiments, numerous ways may be applied in which to provide heat and corrosion resistance to microelectronics packages. These are detailed below and include but are not limited to the following:

[0209] For example, FIGS. 53A-53D depict an alkali silicate glass coating 2410 applied to a flip chip attached and a wire bonded dies for corrosion and tamper resistance. According to one exemplary embodiment (FIGS. 53A-53B), the coating 2410 may be applied to a bare die 2412 that has flip chip attached to circuitry 2416. The coating 2410 may be a thin layer of glass (> lOOnm) that provides a hermetic seal for the die 2412, the circuitry 2416 and/or interconnect members 2420 configured to couple the die 2410 to the circuitry 2416 and therefore protects the components from corrosive elements. An underfill material 2422 may then be applied to the die 2412 and the coated die 2412 may then be further protected by an encapsulant 2414 using standard processing methods. According to another exemplary embodiment (FIGS. 53C-53D), the coating 2410 may be applied to a bare die 2412 that has been wire bonded to circuitry 2416. The coating 2410 may be a thin layer of glass (> lOOnm) that provides a hermetic seal for the die 2412, the circuitry 2416 and/or wires 2424 configured to coupled the die 2410 to the circuitry 2416 and therefore protects the components from corrosive elements. The coated die 2412 may then be further protected by an encapsulant 2414 using standard processing methods.

[0210] Referring now to FIGS. 54A-54B, according to another exemplary embodiment particles may be added to the coating 2410 to make it opaque. The opaque coating solution 2430 may be applied onto a wire bonded die 2412 (FIG. 54A) or flip chip die 2412 (FIG. 54B). Thus, the opaque coating 2430 provides tamper resistance to the die 2412 without exposing it to high processing temperatures. Alternatively, the opaque coating solution 2430 could also be applied under a flip chip.

[0211] Referring now to FIGS. 55A-55B, according to another exemplary embodiment, high thermal conductivity particles, such as diamond, beryllium oxide, and/or aluminum nitride may be added to the coating 2410 prior to applying it to a wire bonded or flip chip die 2412. The resulting coating 2440 (or paste) over the die 2412 possesses a very high thermal conductivity without creating an electrically conductive path. Thus, hot spots on the die 2412 could be easily spread over the entire die surface and conceivably to the board 2416 to which the die 2412 is attached.

[0212] According to another exemplary embodiment, a high thermal conductivity "filled" coating solution 2440 may be used to create a low cost thermal bridges between high temperature components or power dissipating die 2412 and thermal sinks 2442. The coating solution 2440 may be applied and cured at low temperature (< 100⁰C). High thermal conductivity particles such as aluminum nitride, beryllium oxide, and or diamond (thermal conductivity near 2000 W/mK) can be used in this application to provide a highly thermally conducting path.

[0213] Referring now to FIGS. 56A-56B, according to another exemplary embodiment a coefficient of thermal expansion (CTE) matching filler 2452, such as glass or ceramics, may be added to the coating liquid 2450 to increase the bond layer thickness so that the solution can be used as an underfill for flip chip devices 2412. The composite material provides both tamper resistance protection to the die 2412 while improving the thermal cycle and shock loading reliability or the die 2412 as do many other underfills. Another advantage to the coating 2450 and filler 2452 composite is that the composite provides a high- temperature underfill solution (> 700⁰C). Most conventional underfills are limited to relatively low operating temperatures (< 200⁰C). [0214] Referring now to FIGS. 57A-57B, according to another exemplary embodiment a coating 2460 may create 3D wire bondable or flip chip stacked integrated circuits 2412. The coating 2460 provides a unique high-temperature (> 200⁰C) solution for stacked chips 2412. The bond layer thickness of the coating 2460 can be made as thin as lOOnm, allowing for a thin interface formed at low temperature. The coating bonds are very strong and rigid allowing the possibility of wire bonding at higher stack levels without stack compliance (smashing) causing problems. The thinner bonding layers of coating 2460 decreases thermal resistance, thus improving heat transfer. High thermal conductivity particles may also be added to the coating 2460 to improve heat transfer. The coating 2460 provides a stacking adhesives that is hermetic, reducing the likelihood of corrosion and degradation of the bonding interface over time.

[0215] Referring now to FIGS. 58A-58B, according to another exemplary embodiment, a coating 2470 may be applied over high frequency electronic components 2412 to create a low dielectric coating (Er = 3 to 10) to improve RF performance. The devices 2412 may then be encapsulated using standard methods and encapsulants 2414 to improve the reliability and handling characteristics of the devices 2412 without degrading electrical performance.

[0216] While the detailed drawings, specific examples, detailed algorithms and particular configurations given describe preferred and exemplary embodiments, they serve the purpose of illustration only. The embodiments disclosed may be not limited to the specific forms shown. For example, the methods may be performed in any of a variety of sequence of steps or according to any of a variety of mathematical formulas. The configurations shown and described may differ depending on the chosen performance characteristics and physical characteristics of the system. For example, the type of system components and their interconnections may differ. The systems and methods depicted and described may be not limited to the precise details and conditions disclosed. The flow charts show preferred exemplary operations only. The specific data types and operations are shown in a non- limiting fashion. Furthermore, other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the application as expressed in the appended claims.

[0217] It is understood that the specific order or hierarchy of steps in the foregoing disclosed methods are examples of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the method can be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

[0218] It is believed that the present disclosure and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the disclosure or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof, it is the intention of the following claims to encompass and include such changes.

Claims

WHAT IS CLAIMED IS:

1. A circuit board, comprising: a pump; and a channel comprising: a liquid metal; and a coating; wherein the liquid metal is pumped through the channel by the pump and the coating reduces diffusion between the liquid metal and portions of the channel.

2. The circuit board of claim 1, further comprising a heat sink and/or a thermal spreader.

3. The circuit board of claim 1, the pump being an electromagnetic pump and comprising one or more electrodes and one or more magnets, wherein the liquid metal is pumped through the channel by a force generated by the one or more electrodes and one or more magnets.

4. The circuit board of claim 1 , wherein the liquid metal comprises gallium, indium, tin, bismuth, lead, sodium, and/or potassium as constituents.

5. The circuit board of claim 1, further comprising at least one electrical interconnect allowing at least one electrical component to populate the circuit board and form an electronics assembly.

6. The circuit board of claim 1 , wherein the coating passivates the liquid metal from metallic components within the channel to reduce diffusion and chemical reaction between the liquid metal and the metallic components.

7. The circuit board of claim 1, wherein the coating is a hermetic or near hermetic coating.

8. The circuit board of claim 1, wherein the coating is a thermally conductive coating.

9. A circuit board comprising: one or more electrodes; one or more magnets; and a channel comprising: a liquid metal; and a coating wherein, the liquid metal is pumped through the channel by a force generated by the one or more electrodes and one or more magnets and the coating reduces diffusion or alloying between the liquid metal and metallic components in the channel.

10. The circuit board of claim 9, wherein the at least one magnet is an electromagnet.

11. The circuit board of claim 9, wherein the at least one magnet is a permanent magnet.

12. The circuit board of claim 9, wherein the liquid metal is a eutectic gallium-indium-tin alloy.

13. The circuit board of claim 9, wherein the coating is a hermetic or near hermetic coating.

14. The circuit board of claim 13, wherein the coating is a thermally conductive coating.

15. A circuit board comprising: channel means for containing a liquid metal; pump means for pumping the liquid metal through the channel means; and coating means for reducing diffusion and chemical reaction between the liquid metal and other components in the channel.

16. The circuit board of claim 15, wherein the liquid metal comprises gallium, indium, tin, bismuth, lead, sodium, and/or potassium as constituents.

17. The circuit board of claim 16, further comprising at least one electrical interconnect allowing at least one electrical component to populate the substrate and form an electronics assembly.

18. The circuit board of claim 15, wherein the coating means passivates the liquid metal from metallic components within the channel to reduce diffusion between the liquid metal and the metallic components.

19. The circuit board of claim 15, wherein the coating is a hermetic or near-hermetic coating.

20. The circuit board of claim 15, wherein the coating is a thermally conductive coating.

21. A circuit board, comprising: an electronic device operably coupled to current transmission circuitry; an electrode operably coupled to the current transmission circuitry; and a channel comprising a liquid metal, wherein the electrode is configured to transmit current through the channel comprising the liquid metal.

22. The circuit board of claim 21 , further comprising: at least one magnet.

23. The circuit board of claim 22, wherein the liquid metal is pumped through the channel by a force generated by the one or more electrodes and one or more magnets.

24. The circuit board of claim 21 , wherein the electronic device is disposed proximate to the channel comprising liquid metal.

25. The circuit board of claim 21 , wherein the liquid metal comprises one or more of gallium, indium, tin, bismuth, lead, sodium and potassium.

26. The circuit board of claim 21 , further comprising: at least one current shunt.

27. The circuit board of claim 26, further comprising: a ground plane, wherein the at least one current shunt is operably coupled to the ground plane.

28. A method comprising: transmitting a current to a device; transmitting a current from the device across a circuit board channel comprising a liquid metal.

29. The method of claim 28, wherein the transmitting a current from the device across a circuit board channel comprising a liquid metal further comprises: transmitting a current from the device to an electrode.

30. The method of claim 28, further comprising: inducing a velocity of the liquid metal associated with the current transmitted across the circuit board channel comprising the liquid metal.

31. The method of claim 30, wherein the inducing a velocity of the liquid metal associated with the current transmitted across the circuit board channel comprising the liquid metal further comprises: inducing a pumping pressure to the liquid metal proportional to current usage of the device.

32. The method of claim 28, further comprising: transmitting a current from the device to a current shunt.

33. A method comprising : transmitting a current across a circuit board channel comprising a liquid metal; and transmitting the current transmitted across the circuit board channel comprising a liquid metal to a device.

34. The method of claim 33, wherein the transmitting the current transmitted across the circuit board channel comprising a liquid metal to a device further comprises: transmitting a current to one or more electrodes.

35. The method of claim 33 , further comprising : inducing a velocity of the liquid metal associated with the current transmitted across the circuit board channel comprising the liquid metal.

36. The method of claim 35, wherein the inducing a velocity of the liquid metal associated with the current transmitted across the circuit board channel comprising the liquid metal further comprises: inducing a pumping pressure to the liquid metal proportional to current usage of the device.

37. The method of claim 33, further comprising: powering the device with the current transmitted across the circuit board channel comprising a liquid metal.

38. A thermal spreader, comprising: a mechanically flexible substrate, the mechanically flexible substrate forming an internal channel, the internal channel being configured for containing a liquid, the internal channel being further configured to allow for closed-loop flow of the liquid within the internal channel; and a pump, the pump configured for being connected to the mechanically flexible substrate, the pump being further configured for circulating the liquid within the internal channel, wherein the thermal spreader is configured for being connected to a heat source and a heat sink, the thermal spreader being further configured for directing thermal energy from the heat source to the heat sink via the liquid.

39. A thermal spreader as claimed in claim 38, further comprising: an insert, the insert configured for being integrated with the mechanically flexible substrate, the insert being further configured for promoting thermal energy transfer to the liquid and for promoting thermal energy transfer from the liquid.

40. A thermal spreader as claimed in claim 39, wherein the insert includes a first surface and a second surface, the second surface being located generally opposite the first surface, the first surface configured for being oriented toward the internal channel, the second surface configured for being oriented away from the internal channel, the first surface including an extension portion for promoting thermal energy transfer between the insert and the liquid and for providing structural support for the mechanically flexible substrate.

41. A thermal spreader as claimed in claim 40, wherein the insert is a rigid insert and is constructed of metal.

42. A thermal spreader as claimed in claim 41, wherein at least one of: the first surface of the insert; and a liquid contact portion of the mechanically flexible substrate is coated with a layer of alkali silicate glass.

43. A thermal spreader as claimed in claim 42, wherein a thickness value of the layer of alkali silicate glass is a value included in a range of thickness values from 0.1 microns through 10.0 microns.

44. A thermal spreader as claimed in claim 38, wherein the mechanically flexible substrate is at least partially constructed of organic materials.

45. A thermal spreader as claimed in claim 38, wherein the liquid is an electrically conductive liquid and includes at least one of a liquid metal and a liquid metal alloy.

46. A thermal spreader as claimed in claim 45, wherein the liquid metal alloy includes at least two of Gallium, Indium, Tin, Zinc, Lead, and Bismuth.

47. A thermal spreader as claimed in claim 38, wherein the pump is at least one of a piezoelectric positive displacement pump, an inductive pump, and a solid state magnetic pump.

48. A thermal spreader as claimed in claim 40, wherein the extension portion of the first surface of the metal insert is at least one of: a fin, a pin, and a plate.

49. A thermal spreader as claimed in claim 38, wherein the electrically- conductive liquid includes a metal having a melting temperature of less than 50 degrees Celsius.

50. A thermal spreader as claimed in claim 39, wherein the insert is at least partially constructed of at least one of: a graphite foam, a graphite alloy foam, a copper alloy foam, an array of carbon nanotubes, and a thermally conductive filament.

51. A thermal spreader as claimed in claim 46, wherein the mechanically flexible substrate is at least partially constructed of organic-inorganic composite materials including at least one of: glass, ceramics, carbon, metal reinforcements, thin metallic sheets, molded plastic materials, standard circuit board materials, flexible circuit board materials, and rigid-flex circuit cards.

52. A thermal spreader as claimed in claim 38, wherein the heat source is an electronic component connected to a circuit board and the heat sink is a chassis in which the circuit board is mounted.

53. A method for fabricating a thermal spreader, comprising: laminating a plurality of layer portions together to fabricate a mechanically flexible substrate; providing an internal channel within the mechanically flexible substrate, the internal channel configured for containing a liquid, the internal channel being further configured to allow for closed-loop flow of the liquid within the internal channel; integrating a pump with the mechanically flexible substrate; fabricating a plurality of rigid metal inserts; forming a plurality of extension portions on a surface of each rigid metal insert included in the plurality of rigid metal inserts; and connecting the plurality of rigid metal inserts to the mechanically flexible substrate.

54. A method as claimed in claim 53, further comprising: coating a metal portion of a liquid contact surface of the mechanically flexible substrate with a layer of alkali silicate glass.

55. A method as claimed in claim 54, further comprising: coating a liquid contact surface of each rigid metal insert included in the plurality of rigid metal inserts with a layer of alkali silicate glass.

56. A method as claimed in claim 55, further comprising: integrating a plurality of passivation metal-coated electrodes with the mechanically flexible substrate.

57. A method as claimed in claim 53, wherein the mechanically flexible substrate is at least partially constructed of organic materials.

58. A method as claimed in claim 53, wherein the internal channel is provided by one of: forming the internal channel within the mechanically flexible substrate; and integrating the internal channel within the mechanically flexible substrate.

59. A method as claimed in claim 53, wherein the pump is configured for circulating the liquid within the internal channel.

60. A method as claimed in claim 53, wherein the thermal spreader is configured for being connected to a heat source and a heat sink, the thermal spreader being further configured for directing thermal energy from the heat source to the heat sink via the liquid.

61. A method as claimed in claim 53, wherein each rigid metal insert included in the plurality of rigid metal inserts is configured for promoting thermal energy transfer to the liquid and for promoting thermal energy transfer from the liquid.

62. A method for fabricating a plurality of thermal spreaders, comprising: laminating a plurality of layer sheets together to fabricate a mechanically flexible substrate sheet; dicing the mechanically flexible substrate sheet to form a plurality of mechanically flexible substrates; providing an internal channel within each mechanically flexible substrate included in the plurality of mechanically flexible substrates, each internal channel configured for containing a liquid, each internal channel being further configured to allow for closed- loop flow of the liquid within the internal channel; integrating a pump with each mechanically flexible substrate included in the plurality of mechanically flexible substrates, wherein each mechanically flexible substrate included in the plurality of mechanically flexible substrates is at least partially constructed of organic materials.

63. A method as claimed in claim 62, further comprising: fabricating a plurality of rigid metal inserts.

64. A method as claimed in claim 63, further comprising: forming a plurality of extension portions on a surface of each rigid metal insert included in the plurality of rigid metal inserts.

65. A method as claimed in claim 64, further comprising: connecting the plurality of rigid metal inserts to the plurality of mechanically flexible substrates.

66. A method as claimed in claim 65, further comprising: coating a metal portion of liquid contacting surfaces of each mechanically flexible substrate included in the plurality of the mechanically flexible substrates with a layer of alkali silicate glass.

67. A method as claimed in claim 66, further comprising: coating a liquid contacting surface of each rigid metal insert included in the plurality of rigid metal inserts with a layer of alkali silicate glass.

68. A method as claimed in claim 67, further comprising: integrating a plurality of passivation metal-coated electrodes with each mechanically flexible substrate included in the plurality of mechanically flexible substrates.

69. A method for fabricating a plurality of thermal spreaders, comprising: laminating a plurality of layer sheets together to fabricate a mechanically flexible substrate sheet; dicing the mechanically flexible substrate sheet to form a plurality of mechanically flexible substrates; providing an internal channel within each mechanically flexible substrate included in the plurality of mechanically flexible substrates, each internal channel configured for containing a liquid, each internal channel being further configured to allow for closed- loop flow of the liquid within the internal channel; integrating a pump with each mechanically flexible substrate included in the plurality of mechanically flexible substrates; fabricating a plurality of rigid metal inserts; forming a plurality of extension portions on a surface of each rigid metal insert included in the plurality of rigid metal inserts; and connecting the plurality of rigid metal inserts to the plurality of mechanically flexible substrates.

70. A method as claimed in claim 69, further comprising: coating a metal portion of liquid contacting surfaces of each mechanically flexible substrate included in the plurality of the mechanically flexible substrates with a layer of alkali silicate glass.

71. A method as claimed in claim 70, further comprising: coating a liquid contacting surface of each rigid metal insert included in the plurality of rigid metal inserts with a layer of alkali silicate glass.

72. A method as claimed in claim 71, further comprising: integrating a plurality of passivation metal-coated electrodes with each mechanically flexible substrate included in the plurality of mechanically flexible substrates.

73. A magnetic pump for integration with a mechanically flexible thermal spreader, said magnetic pump comprising: a casing, the casing configured for being connected to a mechanically flexible substrate of the thermal spreader; and a plurality of magnets, the plurality of magnets configured for being integrated with and at least partially enclosed by the casing, the plurality of magnets configured for applying a magnetic field to an electrically-conductive liquid, said magnets further configured for implementation with a plurality of electrodes, said electrodes being integrated within the mechanically flexible substrate for generating an electrical current flow through said liquid via a voltage applied across said electrodes, said magnets, in combination with said electrodes, configured for providing a pumping force for circulating the electrically-conductive liquid within an internal channel of an electrically-conductive cooling loop of the mechanically flexible substrate for promoting thermal conductivity of the thermal spreader.

74. A magnetic pump as claimed in claim 73, wherein the pump is a solid-state magnetic pump.

75. A magnetic pump as claimed in claim 73, wherein the mechanically flexible thermal spreader is at least partially constructed of organic materials.

76. A magnetic pump as claimed in claim 73, wherein the magnetic pump is configured for being connected to the thermal spreader via a slotted portion of the mechanically flexible substrate.

77. A magnetic pump as claimed in claim 73, wherein the electrically- conductive liquid includes liquid metal.

78. A magnetic pump as claimed in claim 73, wherein said casing is configured for fully containing the applied magnetic field when connected with said mechanically flexible substrate.

79. A magnetic pump as claimed in claim 73, wherein said casing is constructed of ferrous material.

80. A magnetic pump assembly for integration with a mechanically flexible thermal spreader, said magnetic pump assembly comprising: a casing, the casing configured for being connected to a mechanically flexible substrate of the thermal spreader; a plurality of magnets, the plurality of magnets configured for being integrated with and at least partially enclosed by the casing, the plurality of magnets configured for applying a magnetic field to an electrically-conductive liquid, said magnets further configured for implementation with a plurality of electrodes, said electrodes being integrated within the mechanically flexible substrate for generating an electrical current flow through said liquid via a voltage applied across said electrodes, said magnets, in combination with said electrodes, configured for providing a pumping force for circulating the electrically-conductive liquid within an internal channel of an electrically-conductive cooling loop of the mechanically flexible substrate; and a rigid metal insert, the rigid metal insert configured for being integrated with the casing, wherein said assembly is configured for promoting local thermal conductivity of the thermal spreader.

81. A magnetic pump assembly as claimed in claim 80, wherein the casing forms a plurality of vias, said vias at least partially filled with a thermally-conductive material for further promoting local thermal conductivity of the thermal spreader.

82. A magnetic pump assembly as claimed in claim 80, wherein the pump is a solid-state magnetic pump.

83. A magnetic pump assembly as claimed in claim 80, wherein the mechanically flexible thermal spreader is at least partially constructed of organic materials.

84. A magnetic pump assembly as claimed in claim 80, wherein the electrically-conductive liquid includes liquid metal.

85. A magnetic pump assembly as claimed in claim 80, wherein said casing is configured for fully containing the applied magnetic field when connected with said mechanically flexible substrate.

86. A magnetic pump assembly as claimed in claim 80, wherein the magnetic pump assembly is configured for being connected to the thermal spreader via a slotted portion of the mechanically flexible substrate.

87. A magnetic pump assembly as claimed in claim 80, wherein said casing is constructed of ferrous material.

88. A magnetic pump for integration with a mechanically flexible thermal spreader, said magnetic pump comprising: a casing, the casing configured for being connected to a mechanically flexible substrate of the thermal spreader; a plurality of magnets, the plurality of magnets configured for being integrated with and at least partially enclosed by the casing, the plurality of magnets configured for applying a magnetic field to an electrically-conductive liquid, said magnets further configured for implementation with a plurality of electrodes, said electrodes being integrated within the mechanically flexible substrate for generating an electrical current flow through said liquid via a voltage applied across said electrodes, said magnets, in combination with said electrodes, configured for providing a pumping force for circulating the electrically-conductive liquid within an internal channel of an electrically-conductive cooling loop of the mechanically flexible substrate for promoting thermal conductivity of the thermal spreader, wherein the casing is configured with an input port and an output port, the casing being configured with a plurality of magnet flow channels, said magnet flow channels being located proximal to the output port, said magnet flow channels being further configured for allowing the electrically-conductive liquid to flow through the pump in a first direction, said casing being further configured with a plurality of channel walls, said channel walls configured for separating the magnet flow channels, said channel walls being configured for preventing the generated electrical current flow through said liquid from flowing in a direction generally perpendicular to the first direction, thereby promoting pumping power efficiency of the magnetic pump.

89. A magnetic pump assembly as claimed in claim 88, wherein the pump is a solid-state magnetic pump.

90. A magnetic pump assembly as claimed in claim 88, wherein the mechanically flexible thermal spreader is a low-profile thermal spreader at least partially constructed of organic materials.

91. A magnetic pump assembly as claimed in claim 88, wherein said casing is configured for fully containing the applied magnetic field when connected with said mechanically flexible substrate.

92. A magnetic pump assembly as claimed in claim 88, wherein said casing is constructed of ferrous material.

93. A flexible liquid cooling loop for providing a thermal path between a heat source surface and a heat sink surface, comprising: a plurality of mechanically rigid tubing sections, at least one mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections being configured for contacting the heat source surface, at least one mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections being configured for contacting the heat sink surface; and a plurality of mechanically flexible tubing sections, the plurality of mechanically flexible tubing sections configured for connecting the plurality of mechanically rigid sections to form the loop, wherein the loop is configured for containing a liquid, said loop being further configured for promoting transfer of thermal energy from the heat source surface to the heat sink surface via the loop.

94. A flexible liquid cooling loop as claimed in claim 93, wherein the loop is configured for being integrated with a thermal spreader.

95. A flexible liquid cooling loop as claimed in claim 94, wherein the thermal spreader is a mechanically flexible thermal spreader.

96. A flexible liquid cooling loop as claimed in claim 93, wherein the liquid is an electrically-conductive liquid.

97. A flexible liquid cooling loop as claimed in claim 93, further comprising: a pump, the pump configured for being connected within the loop via a first pair of mechanically flexible tubing sections included in the plurality of mechanically flexible tubing sections, the pump further configured for circulating the liquid within the loop for promoting transfer of heat from the heat source surface to the heat sink surface via the loop.

98. A flexible liquid cooling loop as claimed in claim 97, further comprising: a thermoelectric generator, the thermoelectric generator configured for being connected within the loop via a second pair of mechanically flexible tubing sections included in the plurality of mechanically flexible tubing sections, the thermoelectric generator configured for being positioned within the loop at a heat transfer location for the loop, the thermoelectric generator further configured for tapping a portion of the thermal energy transferred to the loop from the heat source surface and transferred from the loop to the heat sink surface, generating electrical power from said tapped portion of the thermal energy and providing the electrical power to the pump for powering the pump.

99. A flexible liquid cooling loop as claimed in claim 93, wherein the mechanically rigid tubing sections are constructed of metal.

100. A flexible liquid cooling loop as claimed in claim 93, wherein the mechanically rigid tubing sections are constructed of organic materials.

101. A flexible liquid cooling loop as claimed in claim 93, wherein the mechanically flexible tubing sections are constructed of elastomeric materials.

102. A flexible liquid cooling loop as claimed in claim 93, wherein the heat source surface is an electronics component for a vehicle and the heat sink surface is a vehicle mounting plate.

103. A flexible liquid cooling loop as claimed in claim 102, wherein electronics component for the vehicle and the vehicle mounting plate are connected via vibration isolators.

104. A flexible liquid cooling loop as claimed in claim 93, wherein the mechanically rigid tubing sections are generally rectangular tubing sections.

105. A flexible liquid cooling loop as claimed in claim 93, wherein the mechanically rigid tubing sections are connected to the mechanically flexible tubing sections via adhesive.

106. A flexible liquid cooling loop for providing a thermal path between a heat source surface and a heat sink surface, comprising: mechanically flexible tubing; and a plurality of mechanically rigid tubing sections, the plurality of mechanically rigid tubing sections configured for being connected via the mechanically flexible tubing to form the loop, at least one mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections being configured for contacting the heat source surface, at least one mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections being configured for contacting the heat sink surface, wherein the loop is configured for containing a liquid, said loop being further configured for promoting transfer of thermal energy from the heat source surface to the heat sink surface via the loop, said loop being further configured for integration within a mechanically flexible substrate of a mechanically compliant thermal spreader.

107. A flexible liquid cooling loop as claimed in claim 106, wherein the liquid is an electrically-conductive liquid.

108. A flexible liquid cooling loop as claimed in claim 106, further comprising: a pump, the pump configured for being connected into the loop via the mechanically flexible tubing, the pump further configured for circulating the liquid within the loop for promoting transfer of heat from the heat source surface to the heat sink surface via the loop.

109. A flexible liquid cooling loop as claimed in claim 108, further comprising: a thermoelectric generator, the thermoelectric generator configured for being connected into the mechanically flexible tubing, the thermoelectric generator configured for being positioned within the loop at a heat transfer location for the loop, the thermoelectric generator further configured for tapping a portion of the thermal energy transferred to the loop from the heat source surface and transferred from the loop to the heat sink surface, generating electrical power from said tapped portion of the thermal energy and providing the electrical power to the pump for powering the pump.

110. A flexible liquid cooling loop as claimed in claim 106, wherein the mechanically rigid tubing sections are constructed of at least one of: metal and organic materials.

111. A flexible liquid cooling loop as claimed in claim 106, wherein the mechanically flexible tubing is constructed of elastomeric materials.

112. A liquid cooling loop, for providing a thermal path between a heat source surface and a heat sink surface, comprising: a plurality of mechanically rigid tubing sections, each mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections forming a first compartment and a second compartment; and a plurality of mechanically flexible tubing sections, a first set of mechanically flexible tubing sections included in the plurality of mechanically flexible tubing sections being configured for connecting the plurality of mechanically rigid tubing sections via the first compartments of each mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections, a second set of mechanically flexible tubing sections included in the plurality of mechanically flexible tubing sections being configured for connecting the plurality of mechanically rigid tubing sections via the second compartments of each mechanically rigid tubing section included in the plurality of mechanically rigid tubing sections, the plurality of mechanically rigid tubing sections configured for being connected via the first set of mechanically flexible tubing sections and the second set of mechanically flexible tubing sections to form the loop, said first compartments and second compartments preventing physical contact of the first set of mechanically flexible tubing sections and said second set of mechanically flexible tubing sections, wherein the loop is configured for containing a liquid, said loop being further configured for promoting transfer of thermal energy from the heat source surface to the heat sink surface via the loop.