Thermally conductive silicone composition and thermally conductive member

A thermally conductive silicone composition comprising:

• (A) an organopolysiloxane having on average at least two alkenyl groups in a molecule and a viscosity at 25° C. of from 10 to 100,000 mPa·s;
• (B) an organohydrogenpolysiloxane having on average at least two silicon atom-bonded hydrogen atoms in a molecule, the amount of silicon atom-bonded hydrogen atoms in component
• (B) being 0.2 to 5 mols relative to 1 mol of alkenyl groups in component (A);
• (C) a catalytic amount of a hydrosilylation reaction catalyst;
• (D) a thermally conductive filler comprising the following components (D-1) to (D-3):
• (D-1) a thermally conductive powder other than an aluminum nitride powder, said thermally conductive powder having an average particle diameter of 0.1 μm or more and less than 5 μm;
• (D-2) an aluminum nitride powder having an average particle diameter of 20 μm or more and less than 80 μm;
• and
• (D-3) a spherical aluminum oxide powder and/or spherical magnesium oxide powder having an average particle diameter of 80 μm or more, respectively,
• the total amount of components (D-1) to (D-3) being an amount that is 70 to 90% by volume of the present composition, and the amount of component (D-2) being an amount that is 5 to 30% by volume of the present composition;
• and
• (E) a surface treating agent or wetting agent comprising the following components (E-1) and (E-2):
• (E-1) an organopolysiloxane represented by the following general formula:
• R1(R22SiO)mSiR22—R3—SiR2a(OR4)(3-a)
• wherein R1 represents an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, each R2 independently represents an alkyl group having 1 to 6 carbon atoms, R3 represents an oxygen atom or an alkylene group having 2 to 6 carbon atoms, R4 represents an alkyl group having 1 to 3 carbon atoms, “m” represents an integer from 1 to 200, and “a” represents 0, 1, or 2;
• (E-2) an alkoxysilane represented by the following general formula or a partially hydrolyzed condensate thereof:
• R5bR2cSi(OR4)(3-b-c)
• wherein R2 and R4 are the same as described above, R5 represents an alkyl group having 6 to 18 carbon atoms, “b” represents 1 or 2, “c” represents 0 or 1, and (“b”+“c”) is 1 or 2,
• the mass ratio of component (E-1) to component (E-2) being 95:5 to 5:95, the amount of component (E) being 0.1 to 5.0 parts by mass to 100 parts by mass of component (D).