Heat conductive silicone composition and semiconductor device

A heat conductive silicone composition comprising

• (A) 100 parts by weight of an organopolysiloxane containing at least two alkenyl groups in a molecule and having a viscosity of 10 to 100,000 mm2/s at 25° C.,
• (B) an organohydrogenpolysiloxane of the general formula (1):
• wherein R1 is an alkyl group of 1 to 6 carbon atoms, n and m are positive numbers satisfying 0.01≦n/(n+m)≦0.3,
• (C) an organohydrogenpolysiloxane of the general formula (2):
• wherein R2 is an alkyl group of 1 to 6 carbon atoms, and k is a positive number of 5 to 1,000,
• components (B) and (C) being contained in such amounts that the ratio of the number of Si—H groups in components (B) and (C) combined to the number of alkenyl groups in component (A) is from 0.6/1 to 1.5/1, and in such a proportion that the ratio of the number of Si—H groups in component (C) to the number of Si—H groups in component (B) is from 1.0/1 to 10.0/1,
• (D) 800 to 1,200 parts by weight of a filler consisting of aluminum powder having a mean particle size of 0.1 to 50 μm and zinc oxide powder having a mean particle size of 0.1 to 5 μm in a weight ratio of from 1/1 to 10/1,
• (E) a catalyst selected from the group consisting of platinum and platinum compounds, in such an amount as to give 0.1 to 500 ppm of elemental platinum based on the weight of component (A), and
• (F) 0.01 to 1 part by weight of a regulator for suppressing the catalytic activity of component (E),
• said composition having a viscosity of 50 to 1,000 Pa·s at 25° C.