Thermal management materials

• US 6,946,190 B2
• Filed: 05/13/2003
• Issued: 09/20/2005
• Est. Priority Date: 02/06/2002
• Status: Active Grant

• Current Assignee: Parker Intangibles LLC (Parker-Hannifin Corporation)
• Original Assignee: Parker-Hannifin Corporation
• Inventors: Bunyan, Michael H.
• Primary Examiner(s): Ahmed, Sheeba
• Application Number:
  US10/436,764
• Publication Number:
  US 20030203188A1
• Time in Patent Office: 861 Days
• Field of Search: 428/220, 428/323, 428/328, 428/329, 428/330, 428/332, 428/334, 428/340, 428/447, 428/484.1, 428/923, 428/926, 428/484
• US Class Current: 428/334
• CPC Class Codes: C09K 5/063 Materials absorbing or liberating heat during crystallisation; Heat storage materials
• CPC Class Codes: H01L 2224/29294 with a principal constituent of the material being a liquid not provided for in groups H01L2224/292 - H01L2224/29291
• CPC Class Codes: H01L 2224/293 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/29386 with a principal constituent of the material being a non metallic, non metalloid inorganic material
• CPC Class Codes: H01L 2224/29499 Shape or distribution of the fillers
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 23/3737 Organic materials with or without a thermoconductive filler
• CPC Class Codes: H01L 23/4275 by melting or evaporation of solids
• CPC Class Codes: H01L 24/29 of an individual layer connector
• 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 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: Y10S 428/923 Physical dimension
• CPC Class Codes: Y10S 428/926 Thickness of individual layer specified
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide
• CPC Class Codes: Y10T 428/258 Alkali metal or alkaline earth metal or compound thereof
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/263 : Coating layer not in excess of 5 mils thick or equivalent
• CPC Class Codes: Y10T 428/27 : Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
• CPC Class Codes: Y10T 428/31663 : As siloxane, silicone or silane

Abstract

A thermally-conductive compound for forming a layer which is conformable between a first heat transfer surface and an opposing second heat transfer surface to provide a thermal pathway therebetween. The compound is an admixture of a thermal grease component and a dispersed constituent forming discrete domains within the grease component, the domains being form-stable at normal room temperature in a first phase and conformable between the first and second heat transfer surface in a second phase, and the domains having a domain transition temperature above normal room temperature from the first phase to the second phase. The dispersed constituent may be a fusible, i.e., low temperature melting, metal or metal alloy.

Claims

1. A thermal management assembly comprising:

a first heat transfer surface having a first area;

a second heat transfer surface having a second area and opposing said first heat transfer surface; and

a thermally-conductive interface interposed intermediate the first and said second heat transfer surface to provide a thermally-conductive pathway therebetween, the interface having margins smaller than the first and the second area and comprising a thermally-conductive compound formed into a layer which is conformable between the first and second heat transfer surface, the compound comprising an admixture of;

(a) a thermal grease component; and

(b) a dispersed component forming discrete domains within the thermal grease component, the domains being form-stable at normal room temperature in a first phase and conformable between the first and second heat transfer surface in a second phase, and the domains having a transition temperature above normal room temperature from the first phase to the second phases,

wherein the layer has a thickness of about 5 mils (125 μ

m) or less at about room temperature under a given applied pressure, the thickness decreasing by at least about 20% under the given applied pressure within the operating temperature range of the heat-generating source.

2. The assembly of claim 1, wherein the domains have a mean average size of between about 0.4-3 mils (10-75μ

m).

3. The assembly of claim 1 wherein the thermal grease component comprises one or more silicone oils.

4. The assembly of claim 1 wherein the thermal grease component comprises one or more organosiloxane oils.

5. The assembly of claim 1 wherein the layer has a thermal impedance of less than about 1°

C.-in²/W (6°

C.-cm^2/W).

6. The assembly of claim 1 wherein the compound has a thermal conductivity of at least about 0.5 W/m-K.

7. The assembly of claim 1 wherein the compound is substantially self-adherent to one or both of the first and the second heat transfer surface.

8. The assembly of claim 1 wherein the dispersed component comprises one or more fusible metals, one or more fusible metal alloys, or a combination thereof.

9. The assembly of claim 8 wherein the one or more fusible metals or alloys comprises one or more of bismuth, tin, lead, cadmium, and indium.

10. The assembly of claim 8 wherein the dispersed constituent comprises a eutectic alloy, by weight thereof, of about 32.5% bismuth, 16.5% tin, and 50% indium.

11. The assembly of claim 8 wherein the compound comprises, by total weight thereof, between about 5-25% of the one or more fusible metals or metal alloys or combination thereof.

12. The assembly of claim 8 wherein the domain transition temperature is between about 40-80°

C.

13. The assembly of claim 12 wherein the dispersed constituent comprises one or more fusible metals, one or more fusible metal alloys, or a combination thereof.

14. The assembly of claim 8 wherein:

the first heat transfer surface is located on a heat-generating source having an operating temperature range above normal room temperature; and

the domain transition temperature is within the operating temperature range the heat-generating source.

15. The assembly of claim 1 wherein the domains in the second phase form an emulsion with the thermal grease component.

16. The assembly of claim 15 wherein the emulsion has a viscosity of between about 10,000-300,000 cp (10-300 Pa-s).

17. The assembly of claim 1 wherein:

the first heat transfer surface is located on a heat-generating source having an operating temperature range above normal room temperature; and

the transition temperature of the domains is within the operating temperature range the heat-generating source.

18. The assembly of claim 17 wherein:

the heat-generating source is an electronic component; and

the second heat transfer surface is located on a thermal dissipation member.

19. The assembly of claim 18 wherein the thermal dissipation member is a heat sink or a circuit board.

20. The assembly of claim 18 wherein the operating temperature of the heat-generating source is between about 40-80°

C.

21. The assembly of claim 1 wherein the thermal grease component comprises one or more oils selected from the group consisting of mineral oils, hydrocarbon oils, synthetic oils, and silicone oils, and combinations thereof.

22. The assembly of claim 21 wherein the thermal grease component further comprises a thermally-conductive particulate filler.

23. The assembly of claim 22 wherein the dispersed constituent comprises one or more fusible metals, one or more fusible metal alloys, or a combination thereof.

24. The assembly of claim 22 wherein the filler is selected from the group consisting of metal or non-metal oxides, nitrides, carbides, or diboride particles, graphite particles, metal particles, and combinations thereof.

25. The assembly of claim 22 wherein the thermal grease component comprises between about 20-80% by weight of the filler.

26. The assembly of claim 22 wherein the particulate filler has a particle size of between about 0.01-10 mil (0.25-250 μ

m).

27. The assembly of claim 22 wherein the filler has a thermal conductivity of at least about 20 W/m-K.

28. The assembly of claim 22 wherein the thermal grease has a viscosity of between about 10,000-300,000 cp (10-300 Pa-s) at about room temperature.