Thermally conductive sheet
A thermally conductive sheet, comprising a curable resin composition, thermally conductive fibers, and thermally conductive particles, wherein the thermally conductive sheet has a compressibility of 40% or more.
1. A thermally conductive sheet comprising:
a curable resin composition;
thermally conductive fibers; and
thermally conductive particles,
wherein the thermally conductive sheet has a thickness of more than 1.5 mm and 3.0 mm or less,
wherein the thermally conductive sheet has a compressibility of 40% or more, and has a minimum value of a thermal resistance in a load range of 0.5 kgf/cm 2 or more and 3 kgf/cm 2 or less, and
wherein the thermally conductive sheet has a peak value of a thermal conductivity of 15 W/mK or more in the compressibility thereof of 20% or less.
2. The thermally conductive sheet according to claim 1 , wherein
the thermally conductive sheet has a maximum compression stress of less than 780 N when the thermally conductive sheet is compressed by 40% at a rate of 25 mm/min or less.
3. The thermally conductive sheet according to claim 1 , wherein
the thermally conductive sheet has a residual stress of less than 204 N when the thermally conductive sheet is compressed by 40% at a rate of 25 mm/min or less and is held for 10 min in a state of being compressed by 40%.
4. The thermally conductive sheet according to claim 1 , wherein
the curable resin composition is a two-part addition reaction type liquid silicone resin of a silicone base resin and a curing agent; and the silicone base resin and the curing agent are blended at a ratio (silicone base resin:curing agent) of 5:5 to 6:4.
5. The thermally conductive sheet according to claim 1 , wherein
the thermally conductive fibers have an average fiber length of 50 μm or more and 250 μm or less.
6. The thermally conductive sheet according to claim 1 , wherein the thermally conductive sheet has a peak value of a thermal conductivity of 20 W/mK or more in the compressibility thereof of 20% or less.
7. The thermally conductive sheet according to claim 1 , wherein
the thermally conductive sheet has a content of the thermally conductive particles and the thermally conductive fibers of 70% by volume or less.
8. The thermally conductive sheet according to claim 1 , wherein
the thermally conductive sheet is made by cutting a columnar cured product obtained by extruding a thermally conductive composition comprising the curable resin composition, the thermally conductive fibers and the thermally conductive particles, in a substantially perpendicular direction to a longitudinal direction of the columnar cured product.
9. A device comprising:
a heat source;
a heat-dissipating member; and
the thermally conductive sheet according to claim 1 interposed between the heat source and the heat-dissipating member.
10. The device according to claim 9 , wherein
the thermally conductive sheet has a thermal resistance of less by 3% or more than an initial value of the thermal resistance of the thermally conductive sheet interposed between the heat source and the heat-dissipating member.
11. A method for producing a thermally conductive sheet, the method comprising:
extruding a thermally conductive composition comprising a curable resin composition, thermally conductive fibers and thermally conductive particles; and
cutting an extruded columnar cured product in a substantially perpendicular direction to a longitudinal direction of the extruded columnar cured product to thereby obtain the thermally conductive sheet,
wherein in the cutting, the extruded columnar cured product is cut to have a predetermined thickness of more than 1.5 mm and 3.0 mm or less so that the thermally conductive sheet exhibits a maximum compression stress of less than 780 N when the thermally conductive sheet is compressed by 40% at a rate of 25 mm/min or less, and the thermally conductive sheet has a peak value of a thermal conductivity of 15 W/mK or more in a compressibility thereof of 20% or less.
12. The method for producing a thermally conductive sheet according to claim 11 , wherein
in the cutting, the extruded columnar cured product is cut to have the predetermined thickness so that the thermally conductive sheet exhibits a residual stress of less than 204 N when the thermally conductive sheet is compressed by 40% at a rate of 25 mm/min or less and held for 10 min in a state of being compressed by 40%.
13. The method for producing a thermally conductive sheet according to claim 11 , wherein
in the cutting, the extruded columnar cured product is cut to have the predetermined thickness so that the thermally conductive sheet exhibits a thermal resistance of 2.0 K·cm 2 /W or less in a load range of 0.5 kgf/cm 2 or more and 7.5 kgf/cm 2 or less.
14. The method for producing a thermally conductive sheet according to claim 11 , further comprising pressing the thermally conductive sheet cut in the substantially perpendicular direction, wherein
the pressing is carried out so that the thermally conductive sheet has a thermal resistance of 2.0 K·cm 2 /W or less in a load range of 0.5 kgf/cm 2 or more and 7.5 kgf/cm 2 or less.
15. The method for producing a thermally conductive sheet according to claim 14 , wherein
the pressing is carried out at a pressure of 0.1 MPa or more and 30 MPa or less.
16. The method for producing a thermally conductive sheet according to claim 14 , wherein
the pressing is carried out at a temperature of room temperature or more and 140° C. or less.
17. A thermally conductive sheet which is obtained by the method for producing a thermally conductive sheet according to claim 11 .
18. A device comprising:
a heat source;
a heat-dissipating member; and
the thermally conductive sheet according to claim 17 interposed between the heat source and the heat-dissipating member.
19. The device according to claim 18 , wherein
the thermally conductive sheet has a thermal resistance of less by 3% or more than an initial value of the thermal resistance of the thermally conductive sheet interposed between the heat source and the heat-dissipating member.