Thermal contact arrangement

• US 20070076378A1
• Filed: 09/30/2005
• Published: 04/05/2007
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Blanco, Richard
• Granted Patent: US 7,433,191 B2
• Time in Patent Office: Days
• US Class Current: 361/719
• 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 23/433 Auxiliary members in containers characterised by their shape, e.g. pistons
• 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
• CPC Class Codes: H01L 2924/10158 at the passive surface
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49169 Assembling electrical component directly to terminal or elongated conductor
• CPC Class Codes: Y10T 29/4935 Heat exchanger or boiler making

Abstract

A thermal contact arrangement. The thermal contact arrangement may mitigate or reduce migration over time of a thermal interface material positioned between a chip and a heat sink. The thermal contact arrangement may include a first zone formed on a first area of the heat sink and a second zone formed on a second area of the heat sink. The processor may overlap or overlie the first zone, with the second zone generally outside the footprint of the processor and optionally surrounding the processor'"'"'s footprint. The first zone may have a generally smooth surface, while the second zone may have a surface rougher than the first zone. The first zone may be finished to a specific smoothness while the second zone may be finished to second particular smoothness that is generally less than the first zone.

Claims

1. A thermal contact arrangement, comprising:

a thermal conductor;

a first zone having a first surface finish disposed on the thermal conductor; and

a second zone having a second surface finish disposed on the thermal conductor;

wherein

the first surface finish and second surface finish are different.

2. The thermal contact arrangement of claim 1, wherein the first surface finish is smoother than the second surface finish.

3. The thermal contact arrangement of claim 2, wherein:

the first surface finish is approximately 4 microinches root mean square; and

the second surface finish is approximately 125 microinches root mean square.

4. The thermal contact arrangement of claim 2, wherein the second zone surrounds the first zone.

5. The thermal contact arrangement of claim 4, wherein the thermal conductor comprises a heat sink.

6. The thermal contact arrangement of claim 5, further comprising:

a processor operatively connected to the heat sink;

wherein

the first zone approximately corresponds to a footprint of the processor.

7. The thermal contact arrangement of claim 6, further comprising a thermal interface material disposed between the processor and heat sink and operative to thermally couple the processor and heat sink.

8. The thermal contact arrangement of claim 6, wherein:

the first zone and second zone are formed directly from an external surface of the heat sink.

9. The thermal contact arrangement of claim 8, wherein the thermal interface material is disposed adjacent the first zone.

10. The thermal contact arrangement of claim 9, wherein:

the second surface finish establishes a surface tension with the thermal interface material; and

the surface tension resists migration of the thermal interface material from the first zone.

11. A thermal contact arrangement, comprising:

a carrier;

a processor disposed on the carrier;

a thermal interface material adjacent the processor;

a heat sink thermally coupled to the processor by the thermal interface material;

wherein

the heat sink comprises;

a first surface finish defining a first zone; and

a second surface finish defining a second zone, the second surface finish rougher than the first surface finish.

12. The thermal contact arrangement of claim 11, wherein the thermal interface material is chosen from the group comprising:

a thermal grease;

a thermal elastomer;

an oxide-doped thermal grease;

a metal-doped thermal grease;

a thermal adhesive; and

a metallic material

13. The thermal contact arrangement of claim 11, wherein:

a first side of the heat sink and a first side of the processor cooperate to form a thermal joint;

the thermal interface material occupies at least a portion of the thermal joint; and

the first zone and second zone are disposed on the first side of the heat sink.

14. The thermal contact arrangement of claim 13, wherein the second zone at least partially surrounds the first zone.

15. The thermal contact arrangement of claim 14, wherein an area of the first zone is greater than an area of the first side of the processor.

16. The thermal contact arrangement of claim 14, wherein an area of the first zone is less than an area of the first side of the processor.

17. The thermal contact arrangement of claim 14, further comprising a lid positioned over the processor.

18. A method for manufacturing a thermal contact arrangement, comprising the operations:

providing a thermal conductor;

forming a first zone having a first roughness on a first exterior surface of the thermal conductor; and

forming a second zone having a second roughness on the first exterior surface of the thermal conductor;

wherein

the second roughness is rougher than the first roughness.

19. The method of claim 18, wherein the operation of forming a first zone having a first roughness on a first exterior surface of the thermal conductor comprises polishing a first area of the first exterior surface to a desired roughness to form the first zone.

20. The method of claim 19, wherein the operation of forming a second zone having a second roughness on the first exterior surface of the thermal conductor comprises chemically treating a second area of the first exterior surface to a desired roughness to form the second zone.

21. The method of claim 20, further comprising:

providing a carrier;

attaching a processor to the carrier;

positioning the thermal conductor to form, in concert with the processor, a thermal joint; and

placing a thermal interface material in the thermal joint.

22. The method of claim 20, wherein the operation of positioning the thermal conductor to form, in concert with the processor, a thermal joint, comprises:

positioning the first zone adjacent a side of the processor.