Thermal management materials having a phase change dispersion

• US 20030152764A1
• Filed: 10/21/2002
• Published: 08/14/2003
• 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., Young, Kent M.
• Granted Patent: US 7,682,690 B2
• Time in Patent Office: Days
• US Class Current: 428/328
• CPC Class Codes: C09K 5/063 Materials absorbing or liberating heat during crystallisation; Heat storage materials
• CPC Class Codes: H01L 23/4275 by melting or evaporation of solids
• 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 2924/3011 Impedance
• CPC Class Codes: Y10S 428/923 Physical dimension
• 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 428/31801 Of wax or waxy material

Abstract

A thermally-conductive interface interposable intermediate a first heat transfer surface and an opposing second heat transfer surface to provide a thermal pathway therebetween. The interface includes a thermally-conductive compound formed into a layer which is conformable between the first and second heat transfer surface. The compound is an admixture of: (a) a polymeric constituent forming a continuous matrix in the layer; and (b) a dispersed constituent forming discrete domains within the matrix, the domains being form-stable at normal room temperature in a first domain phase and conformable between the first and second heat transfer surface in a second domain phase, and the domains having a domain transition temperature above normal room temperature from the first domain phase to the second domain phase. The dispersed constituent may be a fusible, i.e., low temperature melting, metal or metal alloy.

Claims

1. A thermally-conductive interface interposable intermediate a first heat transfer surface and an opposing second heat transfer surface to provide a thermal pathway therebetween, said interface comprising a thermally-conductive compound formed into a layer which is conformable between the first and second heat transfer surface, said compound comprising an admixture of:

(a) a polymeric constituent forming a continuous matrix in said layer; and

(b) a dispersed constituent forming discrete domains within said matrix, said domains being form-stable at normal room temperature in a first domain phase and conformable between the first and second heat transfer surface in a second domain phase, and said domains having a domain transition temperature above normal room temperature from said first domain phase to said second domain phase.

2. The interface of claim 1 wherein said domain transition temperature is between about 40-80°

C.

3. The interface of claim 2 wherein:

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

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

4. The interface of claim 3 wherein:

said heat-generating source is an electronic component; and

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

5. The interface of claim 4 wherein the thermal dissipation member is a heat sink or a circuit board.

6. The interface of claim 1 wherein said polymeric constituent is inherently tacky such said layer is adherable to one or both of the first or second heat transfer surface.

7. The interface of claim 1 wherein said matrix is form-stable at normal room temperature in a first matrix phase and conformable between the first and second heat transfer surface in a second matrix phase, and said matrix having a matrix transition temperature above normal room temperature from said first matrix phase to said second matrix phase.

8. The interface of claim 7 wherein said matrix transition temperature is lower than the domain transition temperature.

9. The interface of claim 8 wherein said matrix transition temperature is at least about 5°

C. lower than said domain transition temperature.

10. The interface of claim 7 wherein said domains in said second domain phase and said matrix in said second matrix phase form an emulsion in said layer.

11. The interface of claim 7 wherein said polymeric constituent comprises one or more resins, one or more waxes, or a combination thereof.

12. The interface of claim 11 wherein said one or more resins or waxes is selected from the group consisting of thermoplastics, pressure sensitive adhesives, paraffinic waxes, and blends thereof.

13. The interface of claim 7 wherein:

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

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

14. The interface of claim 7 wherein said matrix transition temperature is between about 40-80°

C.

15. The interface of claim 1 wherein said domains have a mean average size of between about 0.4-3 mils (10-75 μ

m).

16. The interface of claim 1 wherein said compound further comprises:

(c) a thermally-conductive particulate filler constituent admixture with said polymeric constituent.

17. The interface of claim 16 wherein said thermally-conductive particulate filler constituent is selected from one or more of the group consisting of metal or non-metal oxide, nitride, carbide, or diboride particles, graphite particles, metal particles, and mixtures thereof.

18. The interface of claim 17 wherein said compound comprises, by total weight of the constituents (a) and (b), between about 20-80% of said thermally-conductive particulate filler constituent.

19. The interface of claim 17 wherein said thermally-conductive particulate filler constituent has a particle size of between about 0.01-10 mil (0.25-250 μ

m).

20. The interface of claim 17 wherein said thermally-conductive particulate filler constituent has a thermal conductivity of between about 25-50 W/m-K.

21. The interface of claim 1 wherein said layer has a thermal impedance of less than about 0.02°

C.-in²/W (0.12°

C.-cm²/W).

22. The interface of claim 1 wherein said layer has a thermal conductivity of at least about 0.7 W/m-K.

23. The interface of claim 1 wherein said layer has a thickness of about 5 mils (125 μ

m) or less.

24. The interface of claim 1 wherein said layer is form-stable at normal room temperature.

25. The interface of claim 1 wherein said dispersed constituent comprises one or more fusible metals, one or more fusible metal alloys, or a combination thereof.

26. The interface of claim 25 wherein said one or more fusible metals or alloys comprises one or more of bismuth, tin, lead, cadmium, and indium.

27. The interface of claim 25 wherein said dispersed constituent comprises a eutectic alloy, by weight thereof, of about 32.5% bismuth, 16.5% tin, and 50% indium.

28. The interface of claim 25 wherein said compound comprises, by total weight thereof, between about 10-70% of said one or more fusible metals or metal alloys, or of said combination thereof.

29. The interface of claim 25 wherein said domain transition temperature is between about 40-80°

C.

30. The interface of claim 7 wherein said dispersed constituent comprises one or more fusible metals, one or more fusible metal alloys, or a combination thereof.

31. The interface of claim 11 wherein said dispersed constituent comprises one or more fusible metals, one or more fusible metal alloys, or a combination thereof.

32. The interface of claim 31 wherein said domains in said second domain phase and said matrix in said second matrix phase form an emulsion in said layer.

33. The interface of claim 32 wherein:

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

said emulsion has a melt flow viscosity of between about 10,000-100,000 cp (10-100 Pa-s) within the operating temperature range of the heat generating source.