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Publication numberUS20010041465 A1
Publication typeApplication
Application numberUS 09/277,894
Publication dateNov 15, 2001
Filing dateMar 29, 1999
Priority dateMar 29, 1999
Also published asUS6358064
Publication number09277894, 277894, US 2001/0041465 A1, US 2001/041465 A1, US 20010041465 A1, US 20010041465A1, US 2001041465 A1, US 2001041465A1, US-A1-20010041465, US-A1-2001041465, US2001/0041465A1, US2001/041465A1, US20010041465 A1, US20010041465A1, US2001041465 A1, US2001041465A1
InventorsJohn Steven Szalay, Haim Feigenbaum, Eric Dean Jensen, Terry Shing Wang
Original AssigneeJohn Steven Szalay, Haim Feigenbaum, Eric Dean Jensen, Terry Shing Wang
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Z-axis electrical interconnect
US 20010041465 A1
Abstract
A Z-axis electrical interconnect includes a flexible printed circuit folded into a U-shape. The Z-axis electrical interconnect also includes a plurality of raised interconnection members arranged on the flexible printed circuit in a predetermined pattern and a circuit trace interconnecting the pair of raised interconnection members. The Z-axis electrical interconnect further includes a spring fixedly positioned on the flexible printed circuit to maintain the U-shape.
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Claims(17)
1. A Z-axis electrical interconnect comprising:
a flexible printed circuit folded into a U-shape;
a plurality of raised interconnection members arranged on the flexible printed circuit in a predetermined pattern;
a circuit trace interconnecting said raised interconnection members; and
a spring fixedly positioned on said flexible printed circuit to maintain the U-shape.
2. A Z-axis electrical interconnect as set forth in
claim 1
wherein said predetermined pattern is a plurality of rows of interconnection members positioned along said flexible printed circuit.
3. A Z-axis electrical interconnect as set forth in
claim 2
wherein said spring is elastomeric.
4. A Z-axis electrical interconnect as set forth in
claim 3
wherein said spring is adhesively bonded to said flexible printed circuit.
5. A Z-axis electrical interconnect as set forth in
claim 4
including a tab extending from an edge of said flexible printed circuit for fixedly retaining the Z-axis electrical interconnect to a device.
6. A Z-axis electrical interconnect as set forth in
claim 5
including an adhesive to bond said tab to the device.
7. A Z-axis electrical interconnect as set forth in
claim 1
wherein said interconnection members are soldered to a device.
8. A Z-axis electrical interconnect for electrically connecting two stacked electrical devices comprising:
a flexible printed circuit folded into a U-shape;
a first row of interconnection members positioned along a distal end of said flexible printed circuit and a second row of interconnection members positioned along a proximate end of said flexible printed circuit;
a circuit trace connecting at least one of said raised interconnection members from said distal end of said flexible printed circuit board with a corresponding one of said raised interconnection members from said proximate end of said flexible printed circuit; and
a spring fixedly positioned between said distal end of said flexible printed circuit and said proximate end of said flexible printed circuit to maintain the U-shape.
9. A Z-axis electrical interconnect as set forth in
claim 8
including a tab extending from an edge of said flexible printed circuit for fixedly retaining the Z-axis electrical interconnect to the electrical device.
10. A Z-axis electrical interconnect as set forth in
claim 8
wherein said spring is elastomeric.
11. A Z-axis electrical interconnect as set forth in
claim 8
wherein said spring is adhesively bonded to said flexible printed circuit.
12. A Z-axis electrical interconnect as set forth in
claim 8
including solder to secure said interconnection members to the electrical device.
13. A Z-axis electrical interconnect as set forth in
claim 9
including an adhesive to bond said tab to the electrical device.
14. A Z-axis electrical interconnect for electrically connecting two stacked electrical devices comprising:
a flexible printed circuit folded into a U-shape;
a first row of interconnection members positioned along a distal end of said flexible printed circuit and a second row of interconnection members positioned along a proximate end of said flexible printed circuit;
a circuit trace connecting one of said raised interconnection members from said distal end of said flexible printed circuit with a corresponding one of said raised interconnection members from said proximate end of said flexible printed circuit;
an elastomeric spring fixedly positioned between said distal end of said flexible printed circuit and said proximate end of said flexible printed circuit to maintain the U-shape; and
a tab extending from an edge of said flexible printed circuit for fixedly retaining the Z-axis electrical interconnect to the devices.
15. A Z-axis electrical interconnect as set forth in
claim 14
wherein said spring is adhesively bonded to said flexible printed circuit.
16. A Z-axis electrical interconnect as set forth in
claim 14
including an adhesive to bond said tab to the devices.
17. A Z-axis electrical interconnect as set forth in
claim 14
including solder to secure said raised interconnection members to the devices.
Description
TECHNICAL FIELD

[0001] The present invention relates generally to electrical interconnects and, more particularly, to a Z-axis electrical interconnect.

BACKGROUND OF THE INVENTION

[0002] Electronic devices are commonly made up of individual components electrically connected together to form a single electrical circuit. An example of an electrical component known in the art is a printed circuit board. Another example is a flexible printed circuit, also known as a flexible circuit. Still another example is an integrated circuit or IC chip. Frequently, it is desirable to connect individual electrical components together. Commonly known electrical interconnection techniques include soldering, socketing, wire bonding, wire button contacts and plug-in connectors.

[0003] As electronic devices physically decrease in size, packaging constraints may limit the use of traditional electrical interconnection techniques.

[0004] For example, stacked electrical components necessitate the use of a Z-axis electrical interconnect. In the past, a wire button contact was used. However, a disadvantage of a wire button contact as a Z-axis electrical interconnect is that it requires a strict vertical dimensional tolerance between the stacked electrical components. Another disadvantage is that the wire button electrical interconnect may not fit in a low profile space. Thus, there is a need in the art for a Z-axis electrical interconnect that is packagable within a low profile space and provides a more positive electrical contact in interconnecting electrical devices.

SUMMARY OF THE INVENTION

[0005] Accordingly, the present invention is a Z axis electrical interconnect. The Z-axis electrical interconnect includes a flexible printed circuit folded into a U-shape. The Z-axis electrical interconnect also includes a plurality of raised interconnection members arranged on the flexible printed circuit in a predetermined pattern and a circuit trace interconnecting the raised interconnection members. The Z-axis electrical interconnect further includes a spring fixedly positioned on the flexible printed circuit to maintain the U-shape.

[0006] One advantage of the present invention is that a Z-axis electrical interconnect is provided having a low profile to fit within a limited space. Another advantage of the present invention is that the Z-axis electrical interconnect allows a lower insertion force during installation. Still another advantage of the present invention is that the Z-axis electrical interconnect provides a positive contact in interconnecting stacked electrical components having a large vertical tolerance. A further advantage of the present invention is that the Z-axis electrical interconnect has connections which may also be tailored to have different locations between the two boards, i.e., a smaller pitch on one board and a larger pitch on the other board, because the signal carrying element is built on a flexible printed circuit (FPC).

[0007] Other features and advantages of the present invention will be readily appreciated as the same becomes better understood after reading the subsequent description when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a perspective view of a Z-axis electrical interconnect illustrating features of the present invention.

[0009]FIG. 2 is a side view of the Z-axis electrical interconnect of FIG. 1.

[0010]FIG. 3 is a perspective view of an installed Z-axis electrical interconnect.

[0011]FIG. 4 is a perspective view of another embodiment of an installed Z-axis electrical interconnect.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0012] Referring to FIGS. 1, 2 and 3, one embodiment of a Z-axis electrical interconnect 10 is illustrated. The Z-axis electrical interconnect 10 includes a flexible printed circuit such as a flexible circuit 12. It should be appreciated that, in this example, the flexible circuit 12 is a mandrel built flexible circuit. For example, to construct a mandrel built flexible circuit 12 a circuit (not shown) is imaged on the mandrel (not shown) in photoresist. The circuit is plated with a conductive material, such as copper. The resist is stripped off of the mandrel. A coverlet film is laminated over the circuit on the mandrel. An example of such a film is a material known as Kapton. While still on the mandrel, a layer of a conductive material such as nickel and a layer of gold is plated onto the pad using the coverlet as a plating resist. The flex is then removed from the mandrel, exposing the circuit traces on the other side of the circuit. A layer of electroless gold or tin-lead may be plated onto the nickel surface to establish a solderable surface. A further example of how this type of flexible circuit 12 is constructed is disclosed in a commonly assigned U.S. Pat. No. 5,207,887 to Crumly, et al., which issued on May 4, 1993, entitled “Semi-Additive Circuitry With Raised Features Using Formed Mandrels”, the disclosure of which is hereby incorporated by reference.

[0013] The Z-axis electrical interconnect 10 includes a raised interconnection member 14 protruding from the flexible circuit 12. The raised interconnection member 14 is a bump made from an electrically conductive material such as copper. Preferably, the Z-axis electrical interconnect 10 includes a plurality of raised interconnection members 14 arranged in a predetermined pattern. In this example, the predetermined pattern is a row of raised interconnection members 14 positioned along a proximate end 16 and a distal end 18 of the flexible circuit 12. It should be appreciated that the raised interconnection member 14 provides a removable electrical contact between stacked first and second electrical devices 20, 22 as illustrated in FIG. 3. It should also be appreciated that the stacked electrical devices 20, 22 may be printed circuit boards.

[0014] The Z-axis electrical interconnect 10 also includes a circuit trace 24 positioned on a surface of the flexible circuit 12. The circuit trace 24 electrically connects the raised interconnection member 14 at the proximate end 16 of the flexible circuit 12 with the corresponding raised interconnection member 14 at the distal end 18 of the flexible circuit 12. It should also be appreciated that, because the Z-axis electrical interconnect 10 has a flexible circuit 12, the interconnect 10 can be tailored to have custom mating locations and raised interconnection members 14 on multiple rows.

[0015] The Z-axis electrical interconnect 10 is folded into a U-shape, with the raised interconnection member 14 facing outwardly. To maintain the shape, the Z-axis electrical interconnect 10 includes a spring 26 fixedly positioned between the proximate and distal ends 16, 18 of the folded flexible circuit 12. The spring 26 is bonded to the flexible circuit 12, such as with an adhesive. Preferably, the spring 12 is elastomeric so as to maintain the shape of the Z-axis electrical interconnect 10 while providing conformity and pressure to the raised interconnection members 14 when in contact with the first and second electrical devices 20, 22. Advantageously, the Z-axis electrical interconnect 10 requires a minimal insertion force to install and maintain contact between the stacked first and second electrical devices 20, 22.

[0016] In operation, the Z-axis electrical interconnect 10 is fixedly retained between the stacked first and second electrical devices 20, 22. The Z-axis electrical interconnect 10 may be retained on the electrical devices 20, 22 by known techniques such as soldering, bonding or fixturing. An example of fixturing is shown in FIG. 4. The Z-axis electrical interconnect 10 includes a tab 28 extending from the flexible circuit 12, such as from a side. Preferably, two tabs 28 are used, although there could be as many as four tabs 28. The Z-axis electrical interconnect 10 is positioned such that the raised interconnection member 14 is aligned with a mating contact (not shown) on the first electrical device 20. The tab 28 is aligned with a corresponding slit 30 in the first electrical device 20, inserted into the slit 30, and fixedly retained, such as by folding the tab 28 over. The tab 28 may also be bonded by an adhesive 31 to the first electrical device 20 to secure the Z-axis electrical interconnect 10 to the first electrical device 20.

[0017] Still another example of fixturing is illustrated in FIG. 2. In this example, solder 32 is used to secure the raised interconnection members 14 onto the first electrical device 20. It should be appreciated that conventional pick and place machines can automate this activity in large volumes.

[0018] The Z-axis electrical interconnect 10 is connected to the second electrical device 22 in a similar manner.

[0019] The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

[0020] Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6815126 *Apr 9, 2002Nov 9, 2004International Business Machines CorporationPrinted wiring board with conformally plated circuit traces
US7165976Apr 27, 2005Jan 23, 2007Japan Aviation Electronics Industry, LimitedIntermediate connector allowing easy retry
US7267553 *May 19, 2006Sep 11, 2007Sumitomo Electric Industries, Ltd.Optical transceiver using optical sub-assembly having multiple lead pins connected to the substrate by a flexible printed circuit
US7303403 *Apr 27, 2006Dec 4, 2007Japan Aviation Electronics Industry, LimitedElectrical connecting member capable of achieving stable connection with a simple structure and connector using the same
US7378227 *Oct 20, 2004May 27, 2008International Business Machines CorporationReduces the tendency of the copper etch step from under-cutting the nickel/gold to cause slivers that cause short circuiting by providing a conforming nickel/gold layer that extends down the side of the traces
US7614884 *May 22, 2008Nov 10, 2009Japan Aviation Electronics Industry, LimitedConnector connectable with low contact pressure
US7794234 *Dec 2, 2008Sep 14, 2010Japan Aviation Electronics Industry, LimitedElectrical connector having a connect portion connecting two contact portions having projections and a drainage at least partially between the projections
US8251712 *Dec 28, 2010Aug 28, 2012Zhen Ding Technology Co., Ltd.Printed circuit board module
US8287289Apr 28, 2009Oct 16, 2012Molex IncorporatedElastic-cushioned capacitively-coupled connector
US20110269319 *Dec 28, 2010Nov 3, 2011Foxconn Advanced Technology Inc.Printed circuit board module
EP1458059A1 *Mar 13, 2003Sep 15, 2004Fred PengConnecting device for connecting electrically a flexible printed board to a circuit board
EP1594192A1Apr 27, 2005Nov 9, 2005Japan Aviation Electronics Industry, LimitedIntermediate connector allowing easy retry
WO2009151806A2 *Apr 28, 2009Dec 17, 2009Molex IncorporatedElastic-cushioned capacitively-coupled connector
Classifications
U.S. Classification439/67, 439/494, 439/492, 439/496, 439/493, 439/495
International ClassificationH01R12/71, H01R12/62, H01R13/24, H05K3/36, H05K1/00
Cooperative ClassificationH01R12/714, H05K2201/056, H05K3/361, H05K3/365, H05K3/368, H05K2201/0367, H01R12/62, H01R13/2435, H01R13/2464
European ClassificationH01R12/62, H01R12/71C2, H05K3/36D, H01R13/24P, H01R13/24D
Legal Events
DateCodeEventDescription
May 16, 2006FPExpired due to failure to pay maintenance fee
Effective date: 20060319
Mar 20, 2006LAPSLapse for failure to pay maintenance fees
Oct 5, 2005REMIMaintenance fee reminder mailed
Mar 17, 2000ASAssignment
Owner name: DELPHI TECHNOLOGIES, INC., MICHIGAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SZALAY, JOHN STEVEN;FEIGENBAUM, HAIM;JENSEN, ERIC DEAN;AND OTHERS;REEL/FRAME:010716/0980
Effective date: 20000228
Owner name: DELPHI TECHNOLOGIES, INC. MAIL CODE: 480-414-420 L