THERMALLY CONDUCTIVE SHEET, PROCESS FOR PRODUCING THE SAME, AND RADIATOR UTILIZING THERMALLY CONDUCTIVE SHEET

• US 20100073882A1
• Filed: 10/29/2007
• Published: 03/25/2010
• Est. Priority Date: 11/01/2006
• Status: Abandoned Application

• Current Assignee: Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Original Assignee: Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Inventors: Yajima, Michiaki, Inada, Teiichi, Yoshikawa, Tooru
• Application Number:
  US12/513,194
• Publication Number:
  US 20100073882A1
• Time in Patent Office: Days
• US Class Current: 361/707
• CPC Class Codes: C08L 33/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C09K 5/14 Solid materials, e.g. powdery or granular
• CPC Class Codes: F28F 21/02 of carbon, e.g. graphite
• CPC Class Codes: H01L 23/373 Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
• CPC Class Codes: H01L 23/3737 Organic materials with or without a thermoconductive filler
• 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: H05K 7/2039 characterised by the heat transfer by conduction from the heat generating element to a dissipating body arrangements for increasing/decreasing heat-transfer, e.g. fins details, F28F13/00
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/24851 Intermediate layer is discontinuous or differential
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Abstract

A thermally conductive sheet having both of a high thermal conductivity and a high flexibility is obtained by providing a thermally conductive sheet including a composition containing:

• • graphite particles (A) in the form of a scale, an elliptic sphere or a rod, a 6-membered ring plane in a crystal thereof being oriented in the plane direction of the scale, the major axis direction of the elliptic sphere, or the major axis direction of the rod; and
  • an organic polymeric compound (B) having a Tg of 50° C. or lower,
  • wherein the plane direction of the scale, the major axis direction of the elliptic sphere, or the major axis direction of the rod of the graphite particles (A) is oriented in the thickness direction of the thermally conductive sheet, the area of the graphite particles (A) exposed onto surfaces of the thermally conductive sheet is 25% or more and 80% or less, and the Ascar C hardness of the sheet is 60 or less at 70° C.

Further there is provided a process for producing, without fail, a thermally conductive sheet advantageously for productivity, costs and energy efficiency and a radiator having a high heat radiating capability.

Claims

1. A thermally conductive sheet, including a composition containing:

graphite particles (A) in the form of a scale, an elliptic sphere or a rod, a 6-membered ring plane in a crystal thereof being oriented in the plane direction of the scale, the major axis direction of the elliptic sphere, or the major axis direction of the rod; and

an organic polymeric compound (B) having a Tg of 50°

C. or lower,

wherein the plane direction of the scale, the major axis direction of the elliptic sphere, or the major axis direction of the rod of the graphite particles (A) is oriented in the thickness direction of the thermally conductive sheet, the area of the graphite particles (A) exposed onto surfaces of the thermally conductive sheet is 25% or more and 80% or less, and the Ascar C hardness of the sheet is 60 or less at 70°

C.

2. The thermally conductive sheet according to claim 1, wherein the average value of the major diameters of the graphite particles (A) is 10% or more of the thickness of the thermally conductive sheet.

3. The thermally conductive sheet according to claim 1, wherein in a particle diameter distribution which is obtained by classifying the graphite particles (A), the amount of the particles having a diameter of ½

or less of the sheet thickness is less than 50% by mass.

4. The thermally conductive sheet according to claim 1, wherein the content of the graphite particles (A) is from 10 to 50% by volume of the whole of the composition.

5. The thermally conductive sheet according to claim 1, wherein the graphite particles (A) are each in the form of a scale, and the plane direction thereof is oriented in the thickness of the thermally conductive sheet and in a single direction in the front and rear planes thereof.

6. The thermally conductive sheet according to claim 1, wherein the organic polymeric compound (B) is a poly(meth)acrylic acid ester polymeric compound.

7. The thermally conductive sheet according to claim 1, wherein the organic polymeric compound (B) includes either or both of butyl acrylate and 2-ethylhexyl acrylate as a copolymerization component, and the amount thereof in the copolymerization composition is 50% or more by mass.

8. The thermally conductive sheet according to claim 1, wherein the composition contains 5 to 50% by volume of a flame retardant.

9. The thermally conductive sheet according to claim 8, wherein the flame retardant is a phosphoric acid ester compound and is further a liquid material having a solidifying point of 15°

C. or lower and a boiling point of 120°

C. or higher.

10. The thermally conductive sheet according to claim 1, wherein the front surface and the rear surface thereof are covered with protective films different from each other in peeling force, respectively.

11. The thermally conductive sheet according to claim 1, wherein the organic polymeric compound (B) has a three-dimensional crosslinked structure.

12. The thermally conductive sheet according to claim 1, a single surface or both surface thereof being provided with an insulating film.

19. A radiator, comprising a thermally conductive sheet according to claim 1, interposed between a heat generating body and a heat radiating body.

20. A heat spreader, comprising a thermally conductive sheet according to claim 1 attached to a formed body which is made of a raw material having a thermal conductivity of 20 W/mK or more and is in the form of a plate or form similar to a plate.

21. A heat sink, comprising a thermally conductive sheet according to claim 1 attached to a formed body which is made of a raw material having a thermal conductivity of 20 W/mK or more and is in the form of a bulk or a bulk having a fin.

22. A heat radiating housing, comprising a thermally conductive sheet according to claim 1 attached to an inner surface of a box which is made of a raw material having a thermal conductivity of 20 W/mK or more.

23. A heat radiating electronic substrate or electric substrate, comprising a thermally conductive sheet according to claim 1 attached to an insulated region of an electronic substrate or electric substrate.

24. A heat radiating pipe or heating pipe, comprising a thermally conductive sheet according to claim 1 used in a joint region of heat radiating pipe pieces or heating pipe pieces, and/or a joint region which is to be fitted to an object to be cooled or object to be heated.

25. A heat radiating luminous body, comprising a thermally conductive sheet according to claim 1 attached to a back surface area of an electric lamp, a fluorescent light, or an LED.

26. A semiconductor device, comprising a semiconductor and a thermally conductive sheet according to claim 1, wherein the thermally conductive sheet diffuses heat generated from the semiconductor.

27. An electronic instrument, comprising an electronic component and a thermally conductive sheet according to claim 1, wherein the thermally conductive sheet diffuses heat generated from the electronic component.

28. A light emitting device, comprising a light emitting element and a thermally conductive sheet according to claim 1, wherein the thermally conductive sheet diffuses heat generated from the light emitting element.

13. A process for producing a thermally conductive sheet, comprising:

subjecting a composition containing;

graphite particles (A) in the form of a scale, an elliptic sphere or a rod, a 6-membered ring plane in a crystal thereof being oriented in the plane direction of the scale, the major axis direction of the elliptic sphere, or the major axis direction of the rod; and

an organic polymeric compound (B) having a Tg of 50°

C. or lower,

to roll forming, press forming, extrusion forming, or painting, so as to have a thickness not more than 20 times the average value of the major diameters of the graphite particles (A), thereby yielding a primary sheet wherein the graphite particles (A) are oriented in a direction substantially parallel to the main surfaces;

laminating the primary sheet, thereby yielding a formed body; and

slicing the formed body at an angle of 0 to 30 degrees to any normal line extending on the primary sheet surfaces.

29. The process for producing a thermally conductive sheet according to claim 13, wherein the formed body is sliced in the temperature range from the Tg of the organic polymeric compound (B)+30°

C. to the Tg−

40°

C.

30. The process for producing a thermally conductive sheet according to claim 13, wherein the slicing of the formed body is performed by use of a slicing member having a flat and smooth board surface having a slit, and a blade protruded from the slit, and

the length of the blade protruded from the slit can be adjusted in accordance with a desired thickness of the thermally conductive sheet.

31. The process for producing a thermally conductive sheet according to claim 30, wherein the slicing is performed while the flat and smooth board surface and/or the blade is cooled into a temperature within the range of −

80°

C. to 5°

C.

32. The process for producing a thermally conductive sheet according to claim 13, wherein the formed body is sliced into a thickness not more than 2 times the weight-average particle diameter obtained by classifying the graphite particles (A).

33. A radiator, comprising a thermally conductive sheet produced by the process according to claim 13 interposed between a heat generating body and a heat radiating body.

34. A heat spreader, comprising a thermally conductive sheet produced by the process according to claim 13 attached to a formed body which is made of a raw material having a thermal conductivity of 20 W/mK or more and is in the form of a plate or form similar to a plate.

35. A heat sink, comprising a thermally conductive sheet produced by the process according to claim 13 attached to a formed body which is made of a raw material having a thermal conductivity of 20 W/mK or more and is in the form of a bulk or a bulk having a fin.

36. A heat radiating housing, comprising a thermally conductive sheet produced by the process according to claim 13 attached to an inner surface of a box which is made of a raw material having a thermal conductivity of 20 W/mK or more.

37. A heat radiating electronic substrate or electric substrate, comprising a thermally conductive sheet produced by the process according to claim 13 attached to an insulated region of an electronic substrate or electric substrate.

38. A heat radiating pipe or heating pipe, comprising a thermally conductive sheet produced by the process according to claim 13 used in a joint region of heat radiating pipe pieces or heating pipe pieces, and/or a joint region which is to be fitted to an object to be cooled or object to be heated.

39. A heat radiating luminous body, comprising a thermally conductive sheet produced by the process according to claim 13 attached to a back surface area of an electric lamp, a fluorescent light, or an LED.

40. A semiconductor device, comprising a semiconductor and a thermally conductive sheet produced by the process according to claim 13, wherein the thermally conductive sheet diffuses heat generated from the semiconductor.

41. An electronic instrument, comprising an electronic component and a thermally conductive sheet produced by the process according to claim 13, wherein the thermally conductive sheet diffuses heat generated from the electronic component.

42. A light emitting device, comprising a light emitting element and a thermally conductive sheet produced by the process according to claim 13, wherein the thermally conductive sheet diffuses heat generated from the light emitting element.

14. A process for producing a thermally conductive sheet, comprising:

subjecting a composition containing;

graphite particles (A) in the form of a scale, an elliptic sphere or a rod, a 6-membered ring plane in a crystal thereof being oriented in the plane direction of the scale, the major axis direction of the elliptic sphere, or the major axis direction of the rod; and

an organic polymeric compound (B) having a Tg of 50°

C. or lower,

to roll forming, press forming, extrusion forming, or painting, so as to have a thickness not more than 20 times the average value of the major diameters of the graphite particles (A), thereby yielding a primary sheet wherein the graphite particles (A) are oriented in a direction substantially parallel to the main surfaces;

winding the primary sheet around the orientation direction of the graphite particles (A) as an axis thereby yielding a formed body; and

slicing the formed body at an angle of 0 to 30 degrees to any normal line extending on the primary sheet surfaces.

15. The process for producing a thermally conductive sheet according to claim 14, wherein the formed body is sliced in the temperature range from the Tg of the organic polymeric compound (B)+30°

C. to the Tg−

40°

C.

16. The process for producing a thermally conductive sheet according to claim 14, wherein the slicing of the formed body is performed by use of a slicing member having a flat and smooth board surface having a slit, and a blade protruded from the slit, and

the length of the blade protruded from the slit can be adjusted in accordance with a desired thickness of the thermally conductive sheet.

17. The process for producing a thermally conductive sheet according to claim 16, wherein the slicing is performed while the flat and smooth board surface and/or the blade is cooled into a temperature within the range of −

80°

C. to 5°

C.

18. The process for producing a thermally conductive sheet according to claim 14, wherein the formed body is sliced into a thickness not more than 2 times the weight-average particle diameter obtained by classifying the graphite particles (A).

43. The process for producing a thermally conductive sheet according to claim 14, wherein the formed body is sliced in the temperature range from the Tg of the organic polymeric compound (B)+30°

C. to the Tg−

40°

C.

44. The process for producing a thermally conductive sheet according to claim 14, wherein the slicing of the formed body is performed by use of a slicing member having a flat and smooth board surface having a slit, and a blade protruded from the slit, and

the length of the blade protruded from the slit can be adjusted in accordance with a desired thickness of the thermally conductive sheet.

45. The process for producing a thermally conductive sheet according to claim 44, wherein the slicing is performed while the flat and smooth board surface and/or the blade is cooled into a temperature within the range of −

80°

C. to 5°

C.

46. The process for producing a thermally conductive sheet according to claim 14, wherein the formed body is sliced into a thickness not more than 2 times the weight-average particle diameter obtained by classifying the graphite particles (A).

47. A radiator, comprising a thermally conductive sheet produced by the process according to claim 14 interposed between a heat generating body and a heat radiating body.

48. A heat spreader, comprising a thermally conductive sheet produced by the process according to claim 14 attached to a formed body which is made of a raw material having a thermal conductivity of 20 W/mK or more and is in the form of a plate or form similar to a plate.

49. A heat sink, comprising a thermally conductive sheet produced by the process according to claim 14 attached to a formed body which is made of a raw material having a thermal conductivity of 20 W/mK or more and is in the form of a bulk or a bulk having a fin.

50. A heat radiating housing, comprising a thermally conductive sheet produced by the process according to claim 14 attached to an inner surface of a box which is made of a raw material having a thermal conductivity of 20 W/mK or more.

51. A heat radiating electronic substrate or electric substrate, comprising a thermally conductive sheet produced by the process according to claim 14 attached to an insulated region of an electronic substrate or electric substrate.

52. A heat radiating pipe or heating pipe, comprising a thermally conductive sheet produced by the process according to claim 14 used in a joint region of heat radiating pipe pieces or heating pipe pieces, and/or a joint region which is to be fitted to an object to be cooled or object to be heated.

53. A heat radiating luminous body, comprising a thermally conductive sheet produced by the process according to claim 14 attached to a back surface area of an electric lamp, a fluorescent light, or an LED.

54. A semiconductor device, comprising a semiconductor and a thermally conductive sheet produced by the process according to claim 14, wherein the thermally conductive sheet diffuses heat generated from the semiconductor.

55. An electronic instrument, comprising an electronic component and a thermally conductive sheet produced by the process according to claim 14, wherein the thermally conductive sheet diffuses heat generated from the electronic component.

56. A light emitting device, comprising a light emitting element and a thermally conductive sheet produced by the process according to claim 14, wherein the thermally conductive sheet diffuses heat generated from the light emitting element.