Heat sink clip and assembly and method of manufacture

• US 4,899,255 A
• Filed: 07/25/1988
• Issued: 02/06/1990
• Est. Priority Date: 07/25/1988
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Case, Maxwell H., Hartzell, Lawrence M., Currier, David W.
• Primary Examiner(s): Envall, Jr., Roy N.
• Application Number:
  US07/223,507
• Time in Patent Office: 561 Days
• Field of Search: 361/386, 361/388, 361/389, 361/381, 357/81, 29/825, 29/839, 29/832
• US Class Current: 361/720
• CPC Class Codes: H01L 23/4093 Snap-on arrangements, e.g. clips
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A through slot is provided in the central apex portion of a U-shaped heat sink clip and results in an advantageous assembly and method of manufacture. A heat sink and power transistor are clamped together by arm portions of the clip. The slot is used either to permit the passage of an insertion tool for holding the clip open during attachment of the clip to the heat sink and power transistor device or to permit passage of external leads of the power transistor. In either case, the resultant heat sink assembly does not require opening of the clip by providing access to ends or outer projections of the clip arm portions by mounting tools or by providing additional exterior clip projections. Thus a much more compact and readily manufacturable heat sink assembly is provided.

Claims

1. A heat sink clip for attaching a power dissipation device to a heat sink, comprising:

a generally U-shaped clip constructed of resilient spring material and having a central apex portion and at least two arm portions forming arms of said U shape, each of said arm portions extending away from associated opposite ends of said central apex portion, respectively, and forming an open end of said clip between said arm portions;

one of said arm portions having a surface thereof for contacting said power dissipation device and biasing it toward said heat sink; and

said central apex portion having a slot therein extending through said central apex portion, whereby said slot permits passage of either a portion of said power dissipation device to be heat sunk or permits passage of an insertion tool which facilitates attaching said heat sink clip about said power dissipation device and said heat sink.

2. A heat sink clip according to claim 1 where said slot extends at least substantially across said central apex portion.

3. A heat sink clip according to claim 2 where said slot substantially extends in a direction between said two arm portions.

4. A heat sink clip according to claim 3 where said clip comprises a unitary metallic member forming said U shape.

5. A heat sink clip according to claim 4 where said metallic member comprises at least one of the materials consisting of beryllium copper and spring steel.

6. A heat sink clip according to claim 2 where said central apex portion is curved in shape between said two arm portions.

7. A heat sink clip according to claim 6 wherein portions of each of said two arm portions at a distance from said central apex portion are nominally spaced apart from each other by a dimension which is less than the spacing between the two arm portions at their juncture to the central apex portion.

8. A heat sink clip according to claim 2 wherein portions of each of said two arm portions at a distance from said central apex portion are nominally spaced apart from each other by a dimension which is less than the spacing between the two arm portions at their juncture to the central apex portion.

9. A heat sink clip according to claim 8 wherein said clip comprises a unitary metallic member forming said U shape.

10. A heat sink clip assembly comprising:

a heat sink having a surface to which a power dissipation device is to be thermally coupled;

a power dissipation device to be attached to said heat sink and having a surface intended for heat transfer coupling to said heat sink surface; and

a heat sink clip for attaching said power dissipation device to said heat sink by providing a force for biasing said power dissipation device surface toward and in thermal conductive contact with said heat sink surface,

wherein said heat sink clip comprises;

a generally U-shaped clip constructed of resilient spring material and having a central apex portion and at least two arm portions forming arms of said U shape, each of said arm portions extending away from associated opposite ends of said central apex portion, respectively, and forming an open end of said clip between said arm portions;

one of said arm portions having a surface thereof coupled to said power dissipation device, said one of said arm portions biasing said power dissipation device surface toward said heat sink surface; and

said central apex portion having a slot therein extending through said central apex portion, whereby said slot permits passage of either a portion of said power dissipation device to be heat sunk or permits passage of an insertion tool which facilitates attaching said heat sink clip about said power dissipation device and said heat sink.

11. A heat sink assembly according to claim 10 wherein another one of said arm portions of said heat sink clip is coupled to said heat sink, said arm portions, therefore, forming a sandwich structure with said heat sink and said power dissipation device therebetween.

12. A heat sink assembly according to claim 11 wherein said slot extends at least substantially across said central apex portion.

13. A heat sink assembly according to claim 12 wherein said slot substantially extends in a direction between said two arm portions.

14. A heat sink assembly according to claim 13 wherein said power dissipation device comprises a body with electrical leads extending away from the body.

15. A heat sink assembly according to claim 14 which includes a circuit board having conductive paths thereon which are connected to said device electrical leads.

16. A heat sink assembly according to claim 15 wherein said electrical leads extend from said device body away from said slot.

17. A heat sink assembly according to claim 15 wherein said electrical leads extend from said device body through said slot and toward said circuit board.

18. A heat sink assembly according to claim 15 wherein said power dissipation device comprises a semiconductor device which includes a metallic plate surface corresponding to said power dissipation device surface.

19. A method for manufacturing a heat sink assembly, comprising the steps of:

providing a heat sink having a surface to which a power dissipation device is to be thermally coupled to;

providing a power dissipation device to be attached to said heat sink and having a surface intended for heat transfer coupling to said heat sink surface;

providing a heat sink clip having a generally U shape and constructed of resilient spring material, said clip having a central apex portion and at least two arm portions extending away from associated opposite ends of said central apex portion, respectively, and forming an open end of said clip between said arm portions, one of said arm portions having a surface thereof to be coupled to said power dissipation device for biasing said power dissipation device surface toward said heat sink surface, said central apex portion having a slot therein extending through said central apex portion;

using at least one tool inserted between said arm portions of said clip to provide said arm portions of said clip further apart than normal;

providing the combination of said heat sink and power dissipation device between said arm portions of said clip while said arm portions are spaced apart further than normal by said one tool; and

removing said one tool and allowing said arm portions to attempt to return to their normal spacing, thus clamping said device and heat sink therebetween, whereby said slot permits passage of either a portion of said power dissipation device to be heat sunk or permits passage of an insertion tool which facilitates attaching said heat sink clip about said power dissipation device and said heat sink.

20. A method according to claim 19 wherein said tool using step includes inserting a first tool into the open end of said U-shaped clip, said first tool having two separable extending projections which initially are adjacent each other and are subsequently separated so as to contact and spread said clip arm portions apart further than normal.

21. A method according to claim 20 wherein said tool using step includes, after said first tool projections have expanded the spacing between said arm portions, inserting a second (transfer) tool through said clip slot, said second tool having projections which, when separated, will contact said arm portions and maintain them in a separated further than normal position.

22. A method according to claim 21 wherein said tool using step includes the step of moving said first tool projections adjacent such that now said second tool projections maintain said arm portions in a further than normal separated position.

23. A method according to claim 22 wherein said removing step includes the step of moving said second tool projections adjacent each other.

24. A method according to claim 23 wherein said removing step includes the step of removing said second tool projections through said slot.

25. A method according to claim 19 wherein said tool using step includes the step of inserting projections of a tool through said clip slot, said projections contacting said arm portions and providing for spacing them apart at said further than normal spacing.

26. A method according to claim 19 wherein said tool using step includes the steps of first providing said heat sink clip with said arm portions positioned on opposite sides of said heat sink and then inserting a tool into the open end of said clip between said arm portions to provide a force between said arm portions to spread said arm portions further apart.

27. A method according to claim 26 wherein said step of providing said heat sink and device between said clip arm portions comprises inserting said device between one of said arm portions and said heat sink while said arm portions are spread apart by said tool being provided between said arm portions.

28. A method according to claim 27 wherein said device has electrical leads extending from a body and wherein during said step of providing said heat sink and device between said clip arm portions, said leads are positioned to extend through said slot.

29. A method according to claim 28 which includes the step of soldering said leads, after said body is positioned between said arm portions and while said leads extend through said slot, to a metallized circuit board positioned on one side of said clip while said device body is positioned on another side of said clip.

30. A method according to claim 19 wherein said tool using step includes inserting a first tool into the open end of said U-shaped clip, said first tool having projections which contact and spread said clip arm portions apart further than normal.