Thermally conductive silicone heat dissipation material

A thermally conductive silicone heat dissipating material comprising:

• a silicone polymer as a matrix resin;
• a first thermally conductive inorganic filler;
• and
• a heat resistance improver,
• wherein the first thermally conductive inorganic filler has a BET specific surface area of 0.3 m2/g or more and is surface treated with a surface treatment agent expressed by Si(OR′)4 or RxSi(OR′)4−x where R represents a hydrocarbon group having 1 to 4 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms, R′ represents a hydrocarbon group having 1 to 4 carbon atoms, and x represents an integer of 1 to 2,
• the thermally conductive silicone heat dissipating material further comprises a second thermally conductive inorganic filler with a BET specific surface area of less than 0.3 m2/g, and the second thermally conductive inorganic filler is not surface treated,
• a content of the first thermally conductive inorganic filler is 100 to 10000 parts by mass with respect to 100 parts by mass of the silicone polymer as the matrix resin,
• the heat resistance improver is at least one selected from the group consisting of α-iron (III) oxide, copper phthalocyanine, cerium octylate, and a benzimidazolone compound,
• a content of the heat resistance improver is 0.01 to 10 parts by mass with respect to 100 parts by mass of the matrix resin, and
• an Asker C hardness of the thermally conductive silicone heat dissipating material after aging at 220° C. for 100 hours in air is minus 15 to 0 compared to an initial hardness, and the Asker C hardness of the thermally conductive silicone heat dissipating material after the aging has further continued at 220° C. for 500 hours in the air is minus 20 to plus 20 compared to the initial hardness.