Heat-dissipating sheet
To provide a heat-dissipating sheet having good close-contact properties with an adherend such as a heat-generating body and being easy to handle. A heat-dissipating sheet includes a heat-dissipating member including a graphite sheet, a first thermally conductive layer, and a second thermally conductive layer stacked in this order. The first thermally conductive layer contains a thermally conductive filler dispersed in a polymer matrix and has an outer shape larger than the graphite sheet when viewed in plan. The second thermally conductive layer contains a thermally conductive filler dispersed in a polymer matrix, is more flexible than the first thermally conductive layer, and has an outer shape identical to or smaller than the first thermally conductive layer when viewed in plan.
1. A heat-dissipating sheet, comprising a heat-dissipating member including a graphite sheet, a first thermally conductive layer, and a second thermally conductive layer stacked in this order,
wherein the first thermally conductive layer contains a thermally conductive filler dispersed in a polymer matrix, and
the second thermally conductive layer contains a thermally conductive filler dispersed in a curing-type polymer matrix, is more flexible than the first thermally conductive layer, and has an outer shape identical to or smaller than the first thermally conductive layer when viewed in plan.
2. The heat-dissipating sheet according to claim 1 , wherein the first thermally conductive layer has an outer shape larger than the graphite sheet when viewed in plan.
3. The heat-dissipating sheet according to claim 2 , wherein the first thermally conductive layer has a type OO hardness of more than 30, and the second thermally conductive layer has a type OO hardness of 30 or less.
4. The heat-dissipating sheet according to claim 1 , wherein the second thermally conductive layer has a polymer matrix content of 50% or less by mass, and the polymer matrix alone has a type OO hardness of 3 or less.
5. The heat-dissipating sheet according to claim 2 , wherein the first thermally conductive layer includes an outer portion that protrudes from an outer shape of the graphite sheet and an inner portion that does not protrude from the outer shape of the graphite sheet when viewed in plan, the outer portion being thicker than the inner portion.
6. The heat-dissipating sheet according to claim 1 , wherein the second thermally conductive layer has lower resilience than the first thermally conductive layer.
7. The heat-dissipating sheet according to claim 1 , further comprising a protective layer disposed on a surface of the heat-dissipating sheet adjacent to the graphite sheet, the protective layer covering the graphite sheet.
8. The heat-dissipating sheet according to claim 1 , further comprising a release layer disposed on at least one of a surface of the heat-dissipating sheet adjacent to the graphite sheet and a surface opposite to the surface.
9. The heat-dissipating sheet according to claim 1 , wherein the content of the thermally conductive filler in the first thermally conductive layer is higher than the thermally conductive filler in the second thermally conductive layer, and the first thermally conductive layer has a higher thermal conductivity than the second thermally conductive layer.
10. The heat-dissipating sheet according to claim 1 , wherein the second thermally conductive layer has a higher thermal conductivity than the first thermally conductive layer.
11. The heat-dissipating sheet according to claim 1 , wherein the graphite sheet is a laminated graphite sheet in which both front and back surfaces of sheet-shaped graphite are laminated with protective films.
12. The heat-dissipating sheet according to claim 1 , wherein the polymer matrix of the second thermally conductive layer is a cured product of an addition reaction-type silicone rubber.