Thermally conductive phase change materials

• US 7,074,490 B2
• Filed: 05/13/2003
• Issued: 07/11/2006
• Est. Priority Date: 12/14/2001
• Status: Expired due to Fees

• Current Assignee: Dow Corning Corporation (Dow, Inc.)
• Original Assignee: Dow Corning Corporation (Dow, Inc.)
• Inventors: Swarthout, Diane Elizabeth, Petroff, Lenin James, Zhang, Shizhong, Feng, Qian Jane
• Primary Examiner(s): Moore, Margaret G.
• Assistant Examiner(s): Zimmer, Marc S.
• Application Number:
  US10/436,862
• Publication Number:
  US 20030224186A1
• Time in Patent Office: 1,155 Days
• Field of Search: 524/404, 524/424, 524/428, 524/430, 524/432, 524/433, 524/439, 524/588, 428/447, 428/450, 428/473.5, 428/474.4, 428/480, 528/25, 528/31, 528/32, 528/34, 427/209
• US Class Current: 428/447
• CPC Class Codes: C08G 77/045 containing less than 25 silicon atoms
• CPC Class Codes: C08G 77/12 containing silicon bound to hydrogen C08G77/045 takes precedence
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08G 77/50 by carbon linkages C08G77/485 takes precedence
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: C09K 5/063 Materials absorbing or liberating heat during crystallisation; Heat storage materials
• CPC Class Codes: F28D 20/02 using latent heat
• CPC Class Codes: F28F 2013/006 Heat conductive materials
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• 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 2924/15311 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/16152 Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane
• CPC Class Codes: Y10T 428/31721 Of polyimide
• CPC Class Codes: Y10T 428/31725 Of polyamide
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]

Abstract

A phase change composition comprises: a matrix comprising an organofunctional silicone wax, and a thermally conductive filler. The composition can be used as a thermal interface material in electronic devices. The composition is formulated to have any desired phase change temperature.

Claims

1. A composition comprising:

A) a matrix comprising an organofunctional silicone wax;

B) a thermally conductive filler;

optionally C) a treating agent;

optionally D) an antioxidant;

optionally E) an inhibitor;

optionally F) a matrix material selected from the group consisting of an organic wax, a polymer compatible with the organofunctional silicone wax, a hardener, and a combination thereof;

optionally G) a vehicle;

optionally H) a wetting agent;

optionally I) an opacifying agent;

optionally J) an antifoaming agent;

optionally K) a pigment;

optionally L) a flame retardant;

optionally M) a spacer,

N) a low melting metal, and

optionally O) a reinforcing filler.

2. The composition of claim 1, where component A) is present in an amount of about 4 to about 10% based on the weight of the composition.

3. The composition of claim 1, where the composition is formulated to have a phase change temperature of at least about 40°

C.

4. The composition of claim 1, where the organofunctional silicone wax comprises an uncrosslinked organofunctional silicone wax.

5. The composition claim 4, where the uncrosslinked organofunctional silicone wax comprises a wax of the formula

R²R³₂SiO(R³₂SiO)_y(R³R¹SiO)_zSiR³₂R², a cyclic wax of the formula

(R³₂SiO)_m(R³R¹SiO)_n, or a combination thereof;

where

each R¹ is independently a substituted or unsubstituted monovalent hydrocarbon group of at least about 16 carbon atoms,

each R² is independently a substituted or unsubstituted monovalent hydrocarbon group,

each R³ is independently a substituted or unsubstituted monovalent hydrocarbon group of at least about 1 carbon atom up to about 4 carbon atoms,

m is greater than or equal to 0,

n is greater than or equal to about 1,

with the proviso that m+n is up to about 8,

y is 0 to about 200, and

z is about 1 to about 200.

6. The composition of claim 5, where each R¹ is an unsubstituted monovalent hydrocarbon group of at least about 16 carbon atoms, each R² is a methyl group, and each R³ is a methyl group.

7. The composition of claim 1, where component A) comprises a crosslinked organofunctional silicone wax.

8. The composition of claim 7, where the crosslinked organofunctional silicone wax comprises a reaction on product of

a) a crosslinking agent comprising an alpha-, omega- diene, an 1-alkenyl-functional organopolysiloxane having at least two 1 -alkenyl groups per molecule, or a combination thereof;

b) an alpha- olefin; and

c) a siloxane having silicon-bonded hydrogen atoms or an organosiloxane having silicon-bonded hydrogen atoms.

9. The composition of claim 1, where component B) is electrically conductive.

10. The composition of claim 1, where component B) is electrically insulating.

11. The composition of claim 1, where component B) comprises aluminum nitride, aluminum oxide, barium titinate, beryllium oxide, boron nitride, diamond, graphite, magnesium oxide, metal particulate, silicon carbide, tungsten carbide, zinc oxide, or a combination thereof.

12. The composition of claim 1, where component C) is present in an amount of at least about 0.05% up to about 5% based on the weight of the composition.

13. The composition of claim 12, where component C) comprises an alkoxysilane having the formula:

R⁵_xSi(OR⁶)_(4-x), where

R⁵ is a substituted or unsubstituted monovalent hydrocarbon group of at least about 1 carbon atoms and up to about 50 carbon atoms,

each R⁶ is independently an unsubstituted, saturated hydrocarbon group of at least about 1 carbon atom and up to about 4 carbon atoms, and x is 1,2, or 3.

14. The composition of claim 1, where component D) is present in an amount of at least about 0.001% up to about 1% based on the weight of the composition.

15. The composition of claim 1, where component E) is present in an amount of at least about 0.001% up to about 1% based on the weight of the composition.

16. The composition of claim 15, where component E) comprises an addition reaction catalyst inhibitor.

17. An interface material comprising I) the composition of claim 1, where the composition is formed as a flat member, a hemispherical nubbin, a convex member, a pyramid, or a cone.

18. The interface material of claim 17, where further comprising II) a release sheet, where the release sheet covers a surface of the composition.

19. The interface material of claim 17, where the composition is coated on a surface of a substrate.

20. The interface material of claim 19, where the substrate comprises a metal foil, a polyamide sheet, a polyimide sheet, or a polyethylene terephthalate polyester sheet.

21. The interface material of claim 19, further comprising II) a release sheet covering a surface of the composition opposite the substrate.

22. A method comprising:

i) interposing the composition of claim 1 along a thermal path between a heat source and a heat spreader.

23. The method of claim 22, wherein the heat source comprises an electronic component.

24. The method of claim 22, where the heat spreader comprises a heat sink, a thermally conductive plate, a thermally conductive cover, a fan, or a circulating coolant system.

25. A device comprising:

a) an electronic component,

b) an interface material, and

c) a heat sink;

where the interface material is arranged along a thermal path extending from a surface of the electronic component to a surface of the heat sink, where the interface material comprises the composition of claim 1.

26. A device comprising:

a) a heat spreader, and

b) an interface material on a surface of the heat spreader,

where the interface material and the heat spreader are configured to comprise a portion of a thermally conductive path between an electronic component and a heat sink, and where the interface material comprises the composition of claim 1.

27. A composition comprising:

A) a matrix comprising a crosslinked organofunctional silicone wax,

B) a thermally conductive filler,

optionally C) a treating agent,

optionally D) an antioxidant, and

optionally B) an inhibitor.

28. The composition of claim 27, where the composition is formulated to have a phase change temperature of at least about 40°

C.

29. The composition of claim 27, where component B) is electrically conductive.

30. The composition of claim 27, where component B) is electrically insulating.

31. The composition of claim 27, where component B) comprises aluminum nitride, aluminum oxide, barium titinate, beryllium oxide, boron nitride, diamond, graphite, magnesium oxide, metal particulate, silicon carbide, tungsten carbide, zinc oxide, or a combination thereof.

32. The composition of claim 27, where component C) is present in an amount of at least about 0.0 5% up to about 5% based on the weight of the composition.

33. The composition of claim 32, where component C) comprises an alkoxysilane having the formula:

R⁵_xSi(OR⁶)_(4-x), where

R⁵ is a substituted or unsubstituted monovalent hydrocarbon group of at least about 1 carbon atoms and up to about 50 carbon atoms,

each R⁶ is independently an unsubstituted, saturated hydrocarbon group of at least about 1 carbon atom and up to about 4 carbon atoms, and x is 1, 2, or 3.

34. The composition of claim 27, where component D) is present in an amount of at least about 0.001% up to about 1% based on the weight of the composition.

35. The composition of claim 27, where component E) is present in an amount of at least about 0.001% up to about 1% based on the weight of the composition.

36. The composition of claim 35, where component E) comprises an addition reaction catalyst inhibitor.

37. The composition of claim 27, further comprising at least one optional component selected from the group consisting of:

F) an optional matrix material selected from the group consisting of organic wax, a polymer compatible with the organofunctional silicone wax, a hardener, and a combination thereof;

G) a vehicle;

H) a wetting agent;

I) an opacifying agent;

J) an antifoaming agent;

K) a pigment;

L) a flame retardant;

M) a spacer;

N) a low melting metal, O) a reinforcing filler; and

a combination thereof.

38. An interface material comprising I) the composition of claim 27, where the composition is formed as a flat member, a hemispherical nubbin, a convex member, a pyramid, or a cone.

39. The interface material of claim 38, where further comprising II) a release sheet, where the release sheet covers a surface of the composition.

40. The interface material of claim 38, where the composition is coated on a surface of a substrate.

41. The interface material of claim 40, where the substrate comprises a metal foil, a polyamide sheet, a polyimide sheet, or a polyethylene terephthalate polyester sheet.

42. The interface material of claim 41, where the composition is coated on two sides of the substrate.

43. The interface material of claim 40, further comprising II) a release sheet covering a surface of the composition opposite the substrate.

44. A method comprising:

i) interposing the composition of claim 27, along a thermal path between a heat source and a heat spreader.

45. The method of claim 44, wherein the heat source comprises an electronic component.

46. The method of claim 44, where the heat spreader comprises a heat sink, a thermally conductive plate, a thermally conductive cover, a fan, or a circulating coolant system.

47. A device comprising:

a) an electronic component

b) an interface material, and

c) an heat sink;

where the interface material is arranged along a thermal path extending from a surface of the electronic component to a surface of the heat sink, where the interface material comprises the composition of claim 27.

48. A device comprising:

a) a heat spreader, and

b) an interface material on a surface of the heat spreader, where the interface material and the heat spreader are configured to comprise a portion of a thermally conductive path between an electronic component and a heat sink, and where the interface material comprises the composition of claim 27.

49. The composition of claim 27, where the crosslinked organofunctional silicone wax comprises a reaction product of:

a) a crosslinking agent comprising an alpha-, omega-diene, an 1-alkenyl-functional organopolysiloxane having at least two 1-alkenyl groups per molecule, or a combination thereof;

b) an alpha-olefin; and

c) a siloxane having silicon-bonded hydrogen atoms or an organosiloxane having silicon-bonded hydrogen atoms.

50. The composition of claim 27, where component A) is present in an amount of about 4 to about 10% based on the weight of the composition.

51. The composition of claim 27, where component B) is present in an amount of about 90 to about 96% based on the weight of the composition.