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Publication numberUS20050092478 A1
Publication typeApplication
Application numberUS 10/697,839
Publication dateMay 5, 2005
Filing dateOct 30, 2003
Priority dateOct 30, 2003
Publication number10697839, 697839, US 2005/0092478 A1, US 2005/092478 A1, US 20050092478 A1, US 20050092478A1, US 2005092478 A1, US 2005092478A1, US-A1-20050092478, US-A1-2005092478, US2005/0092478A1, US2005/092478A1, US20050092478 A1, US20050092478A1, US2005092478 A1, US2005092478A1
InventorsVivek Jairazbhoy, Mohan Paruchuri
Original AssigneeVisteon Global Technologies, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Metal foam heat sink
US 20050092478 A1
Abstract
Further, a system is provided for dissipating heat from a semiconductor module including a semiconductor die and the unitary heat sink. The heat sink comprising a unitary body having both a porous and non-porous portion is provided. The non-porous portion is attached to the semiconductor die and configured to transfer heat to the porous portion for dissipation into the environment. In addition, a method for manufacturing the heat sink is provided.
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Claims(19)
1. A heat sink comprising a unitary body having first and second portions, the first portion being generally non-porous and the second portion being generally porous;
whereby the first portion transfers and spreads heat within the heat sink and the second portion substantially dissipates the heat from the heat sink.
2. The heat sink according to claim 1, wherein the first and second portions are made of a metal material.
3. The heat sink according to claim 1, wherein the first and second portions include a copper alloy.
4. The heat sink according to claim 1, wherein the first portion is generally solid.
5. The heat sink according to claim 1, wherein the second portion has a melting temperature that is lower than a melting temperature of the first portion.
6. A system for dissipating heat comprising:
a semiconductor die; and
a unitary heat sink attached to the semiconductor die, the heat sink including a non-porous portion and a porous portion.
7. The system according to claim 6, wherein the semiconductor die is soldered to the non-porous portion of the unitary heat sink.
8. The system according to claim 6, wherein the heat sink is made of a copper alloy.
9. The system according to claim 6, wherein a melting temperature of the porous portion is lower than a melting temperature of the non-porous portion.
10. The system according to claim 6, wherein a gas is forced through the porous portion of the heat sink.
11. The system according to claim 6, wherein a liquid is forced through the porous portion of the heat sink.
12. The system according to claim 11, wherein the fluid is a dielectric fluid.
13. A method for manufacturing a heat sink comprising the steps of:
forming a unitary body having a first portion therein and a second portion;
melting the second portion of the body; and
creating porosity in the second portion of the body.
14. The method according to claim 13, wherein the first portion has a higher melting temperature than the second portion.
15. The method according to claim 13, wherein the porosity is created by forcing a gas through the second portion.
16. The method according to claim 13, wherein the step of creating porosity includes the step of integrating a material into the second portion.
17. The method according to claim 16, further comprising the step of solidifying the second portion with the material integrated therein.
18. The method according to claim 17, further comprising the step of removing the material from the second portion.
19. The method according to claim 18, wherein the material is removed by a chemical interaction.
Description
    BACKGROUND
  • [0001]
    1. Field of the Invention
  • [0002]
    The present invention generally relates to thermal management of a semiconductor device. More specifically, the invention relates to a metal foam heat sink for thermal management of a semiconductor device.
  • [0003]
    2. Description of Related Art
  • [0004]
    In electronic applications semiconductor devices can generate significant heat performing normal operations. This heat adversely affects the performance and reliability of the devices, if not dissipated. If the heat is not dissipated, the device may overheat such that the junction temperature increases to a level causing the device to fail or function improperly. Devices and interconnects may also fail due to the effects of thermal expansion caused by the overheating. For example, stress caused by a mismatch in thermal expansion between materials can cause solder joint cracking. Therefore, it is advantageous to maximize the capability of a device to remove heat and to minimize the effects of thermal expansion.
  • [0005]
    Heat dissipation from power devices is commonly accomplished with a metal heat sink, either on the top or bottom of the device. The heat sink is typically a metal block or sheet and may include fins. Fins provide additional surface area for the dissipation of heat. Fin structures with high surface area, however, are bulky and expensive often requiring complex machining operations for fabrication.
  • [0006]
    Recently, metal foam has been used in place of fins to aid in the dissipation of heat. The porosity of the metal foam creates an enormous surface area thereby providing high heat dissipation. Metal foam may be attached to a metal block or directly to the semiconductor device. However, utilizing metal foam in conjunction with a block heat sink requires an additional mechanical connection. The mechanical connection may be accomplished using solder or a layer of thermally conductive adhesive. This additional connection increases thermal resistance and hinders effective dissipation of the heat.
  • [0007]
    In view of the above, it is apparent that there exists a need for a heat sink that provides improved heat dissipation.
  • SUMMARY
  • [0008]
    In satisfying the above need, as well as overcoming the enumerated drawbacks and other limitations of the related art, the present invention provides a heat sink comprising a unitary body having both first and second portions, a porous and non-porous portion. The non-porous portion provides for the transfer and spreading of heat while the porous portion provides for heat dissipation. When implemented in a semiconductor module, including a semiconductor die and the heat sink, the non-porous portion of the heat sink is attached to the semiconductor die and configured to transfer heat to the porous portion, which dissipates the heat into the environment.
  • [0009]
    In yet another aspect of the invention, a method for manufacturing the heat sink is provided. The method includes the steps of forming a body having a first and a second portion, melting the second portion, and creating porosity in the second portion. The heat sink is made of a metal material, preferably a copper alloy. The alloy content of the portions may be varied such that the melting temperature of the second portion is lower than the melting temperature of the first portion. The varying melting temperature allows porosity to be created in the second portion. This can be achieved by forcing gas through the second portion or by inserting a material into the second portion that may be removed, by burning or chemical reaction, after the second portion has solidified.
  • [0010]
    Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0011]
    FIG. 1 is a cutaway side view of a heat dissipating system in accordance with the present invention and implemented in connection with a semiconductor module.
  • DETAILED DESCRIPTION
  • [0012]
    Referring now to FIG. 1, a system embodying the principles of the present invention is illustrated therein and designated at 10. The system 10 generally includes a semiconductor die 12 and a heat sink 14.
  • [0013]
    A semiconductor die 12 generates heat while performing its normal operations. The die 12 is soldered to the metal vias 24. The metal vias 24 transfer the heat generated by the die 12 to the heat sink 14 at the opposite side of the printed circuit board 22. The heat sink 14 is attached to the thermal vias 24 and the printed circuit board 22 by a thermally conductive adhesive 20. However, other means of attachment including solder may be utilized.
  • [0014]
    The heat sink 14 includes a solid non-porous portion 16 and a porous portion 18. The non-porous portion 16 provides a thermal mass for heat spreading or sinking. The non-porous portion 16 also provides the ability to absorb short term transients allowing quick transfer of the heat away from the die. The porous portion 18 of the heat sink 14 provides an extremely large surface area for dissipation of the heat into the surrounding environment. Although, the heat sink 14 is described as a porous portion 18 and a non-porous portion 16 the heat sink is a single unitary structure thereby eliminating mechanical interfaces which may increase thermal resistance.
  • [0015]
    Natural convection may be used to dissipate heat from the porous portion 18 of the heat sink 14. However, air or liquid may also be forced through the porous section 18 of the heat sink 14. The flow of the gas or liquid cooling is illustrated by arrow 28. The heat sink 14 is preferably made of copper although aluminum or other metals may be used. In addition, the pore sizes and the thickness of each portion may be manipulated based on the package size and amount of heat to be dissipated.
  • [0016]
    In addition, a method for manufacturing the heat sink is provided. The heat sink will have a unitary body including a first and second portion. The first portion can be a solid non-porous metal block, and may include a higher alloy content thereby causing the first portion to have a higher melting temperature than the second portion. The second portion may be melted at a temperature such that the first portion remains solid. A porosity is then created in the melted or second portion of the heat sink. The porosity may be created by forcing gas through the melted portion. Alternatively, a foreign material may be inserted into the melted portion. With the foreign material integrated, the second portion may be allowed to solidify creating a porous surface area of the second portion. After solidification of the second portion, the foreign material may be removed by burning, chemical vaporization or other methods. Additional manufacturing operations may then be performed to the heat sink including milling, drilling, or similar operations.
  • [0017]
    As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.
Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4012770 *Sep 28, 1972Mar 15, 1977Dynatherm CorporationCooling a heat-producing electrical or electronic component
US4106188 *Jul 1, 1977Aug 15, 1978Hughes Aircraft CompanyTransistor cooling by heat pipes
US4222434 *Apr 27, 1978Sep 16, 1980Clyde Robert ACeramic sponge heat-exchanger member
US4381818 *Mar 26, 1980May 3, 1983International Business Machines CorporationPorous film heat transfer
US4995451 *Dec 29, 1989Feb 26, 1991Digital Equipment CorporationEvaporator having etched fiber nucleation sites and method of fabricating same
US5180001 *Aug 2, 1990Jan 19, 1993Hitachi, Ltd.Heat transfer member
US5205353 *Feb 18, 1992Apr 27, 1993Akzo N.V.Heat exchanging member
US5210440 *Jun 3, 1991May 11, 1993Vlsi Technology, Inc.Semiconductor chip cooling apparatus
US5252921 *Mar 14, 1991Oct 12, 1993Research Development Corporation Of JapanNoise canceling high-sensitive magnetometer
US5349498 *Dec 23, 1992Sep 20, 1994Hughes Aircraft CompanyIntegral extended surface cooling of power modules
US5402004 *Feb 12, 1993Mar 28, 1995Texas Instruments IncorporatedHeat transfer module for ultra high density and silicon on silicon packaging applications
US5448108 *Nov 2, 1993Sep 5, 1995Hughes Aircraft CompanyCooling of semiconductor power modules by flushing with dielectric liquid
US5606201 *May 24, 1993Feb 25, 1997Mannesmann AktiengesellschaftFluid-cooled power transistor arrangement
US5780928 *Apr 9, 1996Jul 14, 1998Lsi Logic CorporationElectronic system having fluid-filled and gas-filled thermal cooling of its semiconductor devices
US5880524 *May 5, 1997Mar 9, 1999Intel CorporationHeat pipe lid for electronic packages
US5986885 *Apr 8, 1997Nov 16, 1999Integrated Device Technology, Inc.Semiconductor package with internal heatsink and assembly method
US6037658 *Oct 7, 1997Mar 14, 2000International Business Machines CorporationElectronic package with heat transfer means
US6186768 *Sep 4, 1998Feb 13, 2001Electrovac, Fabrikation Elektrotechnischer Spezialartikel Gesellschaft M.B.H.Metal matrix composite (MMC) body
US6196307 *Jun 17, 1998Mar 6, 2001Intersil Americas Inc.High performance heat exchanger and method
US6397450 *May 12, 2000Jun 4, 2002Intersil Americas Inc.Method of cooling an electronic power module using a high performance heat exchanger incorporating metal foam therein
US6400012 *Sep 17, 1997Jun 4, 2002Advanced Energy Voorhees, Inc.Heat sink for use in cooling an integrated circuit
US6411508 *Aug 16, 2000Jun 25, 2002Korea Institute Of Science And TechnologyFoam metal heat sink
US6424531 *Jun 25, 2001Jul 23, 2002Delphi Technologies, Inc.High performance heat sink for electronics cooling
US6473303 *Feb 12, 2001Oct 29, 2002Abb Schweiz AgCooling device for a high-power semiconductor module
US6535388 *Oct 4, 2001Mar 18, 2003Intel CorporationWirebonded microelectronic packages including heat dissipation devices for heat removal from active surfaces thereof
US6591897 *Feb 20, 2002Jul 15, 2003Delphi Technologies, Inc.High performance pin fin heat sink for electronics cooling
US6660224 *Aug 27, 2001Dec 9, 2003National Research Council Of CanadaMethod of making open cell material
US6705393 *Feb 25, 2003Mar 16, 2004Abc Taiwan Electronics Corp.Ceramic heat sink with micro-pores structure
US20030233268 *Jun 17, 2002Dec 18, 2003Ehsan TaqbeemMulti-dimensional interdependency based project management
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7930820Sep 26, 2005Apr 26, 2011International Business Machines CorporationMethod for structural enhancement of compression system board connections
US8929086Sep 26, 2005Jan 6, 2015International Business Machines CorporationGel package structural enhancement of compression system board connections
US9179579 *Jun 6, 2007Nov 3, 2015International Business Machines CorporationSheet having high thermal conductivity and flexibility
US20070044941 *Aug 30, 2005Mar 1, 2007Ching-Lin KuoHeatsink having porous fin
US20070069358 *Sep 26, 2005Mar 29, 2007International Business Machines CorporationGel package structural enhancement of compression system board connections
US20070069754 *Sep 26, 2005Mar 29, 2007International Business Machines CorporationGel package structural enhancement of compression system board connections
US20080089024 *Dec 3, 2007Apr 17, 2008International Business Machines CorporationMulti-Chip Module (MCM) of a Computer System
US20090139690 *Nov 25, 2008Jun 4, 2009Fraunhofer-Gesellschaft Zur, Foerderung Der Angewandten, Forschung E. V.Heat sink and method for producing a heat sink
US20110198067 *Jun 6, 2007Aug 18, 2011International Business Machines CorporationSheet having high thermal conductivity and flexibility
Classifications
U.S. Classification165/185, 257/E23.098, 257/E23.112
International ClassificationF28F13/00, H05K1/02, H01L23/373, H01L23/473
Cooperative ClassificationF28F13/003, H05K2201/066, H01L23/3733, H05K2201/0116, H01L23/473, H05K1/0206, H01L2924/0002
European ClassificationH05K1/02B2B2, F28F13/00B, H01L23/373H
Legal Events
DateCodeEventDescription
Oct 30, 2003ASAssignment
Owner name: VISTEON GLOBAL TECHNOLOGIES, INC., MICHIGAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:JAIRAZBHOY, VIVEK;PARUCHURI, MOHAN;REEL/FRAME:014655/0591
Effective date: 20031027