SRAM heat sink assembly and method of assembling

• US 6,243,264 B1
• Filed: 08/30/1999
• Issued: 06/05/2001
• Est. Priority Date: 08/30/1999
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Jones, James A., Zhang, Ron, Bollesen, Vernon P.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): CHERVINSKY, BORIS LEO
• Application Number:
  US09/385,474
• Time in Patent Office: 645 Days
• Field of Search: 361/704, 361/707, 361/709, 361/710, 361/717-721, 361/722, 165/80.2, 165/80.3, 165/185, 174/16.3, 251/706, 251/707, 251/712, 251/713, 251/726, 251/727, 251/718, 251/719
• US Class Current: 361/704
• 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 heat sink assembly includes a heat sink, a circuit board and an integrated circuit package. The package is located between the heat sink and the circuit board and attached to a die attach area of the circuit board. A heat sink retainer attached to the heat sink has a base section located adjacent to the circuit board directly opposite the die attach area. The retainer presses the heat sink down uniformly on the package. Further, the downward force applied to the heat sink is countered by an equal upward force applied by the base section of the retainer on the circuit board. Since the base section is located directly opposite the die attach area, the upward force is transferred from the base section directly back to the heat sink without imparting any bending force on the circuit board.

Claims

1. A structure comprising:

a heat sink comprising a first aperture and a second aperture;

a circuit board;

a package comprising an electronic component, wherein said package is located between said heat sink and said circuit board and attached to a die attach area of said circuit board; and

a retainer comprising;

a base section located adjacent said circuit board directly opposite said die attach area, said base section supporting said circuit board;

a first hook-shaped fastener;

a first spring element connecting said first hook-shaped fastener to a first edge of said base section, said first spring element comprising a first riser arm, a diameter of said first aperture of said heat sink being less than a distance between a tip of said first hook-shaped fastener and said first riser arm;

a second hook-shaped fastener; and

a second spring element connecting said second hook-shaped fastener to a second edge of said base section, said second spring element comprising a second riser arm, a diameter of said second aperture of said heat sink being less than a distance between a tip of said second hook-shaped fastener and said second riser arm.

2. The structure of claim 1 wherein said retainer passes through apertures in said circuit board and attaches to said heat sink, said retainer pressing said heat sink towards said package without imparting a bending force on said circuit board.

3. The structure of claim 1 wherein said first hook-shaped fastener presses on a first lip of said heat sink and wherein said second hook-shaped fastener presses on a second lip of said heat sink, said heat sink further comprising:

a first ridge extending from said first lip to prevent said first hook-shaped fastener from slipping from said first lip; and

a second ridge extending from said second lip to prevent said second hook-shaped fastener from slipping from said second lip.

4. The structure of claim 1 wherein said base section comprises at least one aperture.

5. A structure comprising:

a retainer comprising;

a plurality of hook-shaped fasteners;

a base section having a plurality of edges; and

a plurality of spring elements, wherein each spring element of said plurality of spring elements comprises a riser arm and connects a different hook-shaped fastener of said plurality of hook-shaped fasteners to a different edge of said plurality of edges; and

a heat sink having a plurality of apertures corresponding to said plurality of hook-shaped fasteners, wherein a diameter of each aperture of said plurality of apertures is less than a distance between each tip of said plurality of hook-shaped fasteners and a respective one of said riser arms.

6. The structure of claim 5 further comprising a substrate having a plurality of apertures corresponding to said plurality of hook-shaped fasteners, each of said riser arms passing through a corresponding aperture of said plurality of apertures in said substrate.

7. The structure of claim 6 further comprising a package comprising an electronic component, said package located between said heat sink and said substrate.

8. The structure of claim 7 wherein said package is attached to a die attach area of said substrate, said base section being located adjacent said substrate directly opposite said die attach area.

9. The structure of claim 5 wherein each spring element of said plurality of spring elements comprises a spring arm attached to said base section.

10. The structure of claim 5 wherein a number of said plurality of hook-shaped fasteners is greater than two.

11. The structure of claim 5 wherein said retainer is symmetric around a center line of said retainer.

12. The structure of claim 5 wherein said retainer has the ability to return to its original form after being bent out of shape.

13. A method of pressing a heat sink into thermal contact with a package comprising an electronic component, said method comprising:

attaching said package to a die attach area of a substrate;

positioning said heat sink such that said package is located between said heat sink and said substrate; and

attaching fasteners of a retainer to said heat sink by passing said fasteners through apertures in said heat sink, wherein said fasteners are compressed while passing through said apertures, wherein said fasteners impart a first force on said heat sink, said first force being countered by an opposite second force applied by a base section of said retainer on said substrate directly opposite said die attach area.

14. The method of claim 13 wherein said first force and said second force are applied without imparting a bending force to said substrate.

15. The method of claim 13 wherein said fasteners return to their relaxed state after passing through said apertures.

16. The method of claim 13 wherein said fasteners are attached to said base section by spring elements, said attaching comprising placing said spring elements under tension.

17. The method of claim 13 wherein said fasteners press against lips of said heat sink, said method further comprising preventing said fasteners from slipping from said lips.

18. The method of claim 17 wherein ridges extending from said lips prevent said fasteners from slipping from said lips.