Flexible circuit electronic package with standoffs

• US 7,851,906 B2
• Filed: 03/26/2007
• Issued: 12/14/2010
• Est. Priority Date: 03/26/2007
• Status: Expired due to Fees

• Current Assignee: I3 ELECTRONICS, INC.
• Original Assignee: Endicott Interconnect Technologies Incorporated
• Inventors: Calmidi, Varaprasad V., Alcoe, David J.
• Primary Examiner(s): Mandala; Victor A
• Assistant Examiner(s): STOWE, SCOTT C
• Application Number:
  US11/727,314
• Publication Number:
  US 20080237840A1
• Time in Patent Office: 1,359 Days
• Field of Search: 257/678, 257/687, 257/712, 257/713, 257/717, 257/706, 257/707, 257/720, 257/E23.101, 257/E23.102, 257/E23.11, 257/E23.104, 361/704, 438/106, 438/118, 438/122, 438/125
• US Class Current: 257/713
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 23/367 Cooling facilitated by shape of device H01L23/38, H01L23/40, H01L23/42, H01L23/44, H01L23/46 take precedence
• CPC Class Codes: H01L 23/40 Mountings or securing means for detachable cooling or heating arrangements heating H01L23/345; fixed by friction, plugs or springs
• CPC Class Codes: H01L 23/42 Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
• CPC Class Codes: H01L 23/5387 Flexible insulating substrates H01L23/5388 takes precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01087 Francium [Fr]
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]

Abstract

A flexible circuit electronic package including a heat sink, a flexible circuit having a semiconductor chip positioned thereon and electrically coupled thereto, and a quantity of heat shrunk adhesive securing the flexible circuit to the heat sink such that the flexible circuit is planar. This package is then adapted for being positioned on and electrically coupled to a circuitized substrate such as a printed circuit board. A method of making this package is also provided.

Claims

1. An electronic package comprising:

a heat sink;

a flexible circuit including a plurality of conductors thereon;

a semiconductor chip positioned on said flexible circuit and electrically coupled to selected ones of said conductors;

a quantity of heat shrunk adhesive positioned on said flexible circuit and bonding said flexible circuit to said heat sink such that said flexible circuit having said semiconductor chip positioned thereon is substantially planar; and

a plurality of separate standoffs positioned between said heat sink and said flexible circuit to separately contact and maintain at least part of said flexible circuit at a spaced distance from said heat sink, so as to limit motion of said flexible circuit due to permanent volumetric shrinkage of heat shrunk adhesive;

wherein at least one of the plurality of separate standoffs does not contact the heat shrunk adhesive, and wherein at least one of said plurality of separate standoffs is positioned within said quantity of heat shrunk adhesive.

2. The electronic package of claim 1 wherein said separate standoffs comprise inorganic material.

3. The electronic package of claim 2 wherein said separate standoffs comprise glass.

4. The electronic package of claim 1 wherein said separate standoffs comprise of metal.

5. The electronic package of claim 4 wherein said separate standoffs are solder elements.

6. The electronic package of claim 1 wherein said separate standoffs are electronic components.

7. The electronic package of claim 6 wherein said separate standoffs are semiconductor chip and solder ball assemblies.

8. The electronic package of claim 1 wherein at least one of said separate standoffs is positioned contiguous to said quantity of heat shrunk adhesive.

9. The electronic package of claim 8 wherein said separate standoffs comprise of inorganic material.

10. The electronic package of claim 9 wherein said separate standoffs comprise of glass.

11. The electronic package of claim 8 wherein said separate standoffs comprise of metal.

12. The electronic package of claim 11 wherein said separate standoffs are solder elements.

13. The electronic package of claim 8 wherein said separate standoffs are electronic components.

14. The electronic package of claim 13 wherein said separate standoffs are semiconductor chip and solder ball assemblies.

15. The electronic package of claim 1 wherein said separate standoffs comprise extension portions of said heat sink.

16. The electronic package of claim 1 wherein said heat shrunk adhesive comprises silicone.

17. The electronic package of claim 1 further including a printed circuit board, said flexible circuit of said electronic package being electrically coupled to said printed circuit board to form an electrical assembly.

18. A method of making an electronic package comprising:

providing a heat sink;

providing a flexible circuit including a plurality of conductors thereon;

positioning a semiconductor chip on said flexible circuit and electrically coupling said semiconductor chip to selected ones of said conductors;

positioning a quantity of heat shrinkable adhesive in liquidus form between said flexible circuit and said heat sink in contact with both said flexible circuit and said heat sink;

substantially shrinking said heat shrinkable adhesive to cause said heat shrinkable adhesive to shrink from the volume of its liquidus form to a lesser volume so as to bond said flexible circuit to said heat sink such that said flexible circuit having said semiconductor chip positioned thereon is substantially planar; and

positioning a plurality of separate standoffs substantially between said heat sink and said flexible circuit to maintain at least part of said flexible circuit at a spaced distance from said heat sink when said flexible circuit is substantially planar;

wherein at least one of the plurality of separate standoffs does not contact the heat shrinkable adhesive, and wherein at least one of the plurality of separate standoffs is positioned within the heat shrinkable adhesive.

19. The method of claim 18 wherein said positioning of said semiconductor chip on said flexible circuit and electrically coupling said semiconductor chip to selected ones of said conductors is accomplished using solder balls.

20. The method of claim 18 wherein said positioning of said quantity of heat shrinkable adhesive in liquidus form between said flexible circuit and said heat sink in contact with both said flexible circuit and said heat sink is accomplished using a dispenser nozzle.

21. The method of claim 18 wherein said substantially curing of said heat shrinkable adhesive to cause said heat shrinkable adhesive to shrink from the volume of its liquidus form to a lesser volume so as to bond said flexible circuit to said heat sink such that said flexible circuit having said semiconductor chip positioned thereon is substantially planar is accomplished by exposing said heat shrinkable adhesive to air at room temperature for a predetermined time period.

22. The method of claim 18 wherein said substantially curing of said heat shrinkable adhesive to cause said heat shrinkable adhesive to shrink from the volume of its liquidus form to a lesser volume so as to bond said flexible circuit to said heat sink such that said flexible circuit having said semiconductor chip positioned thereon is substantially planar is accomplished by exposing said heat shrinkable adhesive to heat at an established temperature for a predetermined time period.

23. The method of claim 22 wherein said established temperature is within the range of from about 140 degrees Celsius to about 160 degrees Celsius and said predetermined time period is from about 30 minutes to about 120 minutes.

24. The method of claim 18 wherein said positioning of said plurality of separate standoffs substantially between said heat sink and said flexible circuit to maintain at least part of said flexible circuit at a spaced distance from said heat sink when said flexible circuit is substantially planar includes positioning at least one of said separate standoffs contiguous with said heat shrinkable adhesive.