Curable organopolysiloxane composition, method of curing thereof, semiconductor device, and adhesion promoter

A curable organopolysiloxane composition comprising:

• 100 parts by weight of (A) a mixture of (A1) a liquid organopolysiloxane of an average unit formula:
• RaSiO(4-a)/2 that contains in one molecule at least two unsaturated aliphatic groups and has a viscosity at 25° C. within the range of 10 to 100,000 mPa·s, wherein R designates an unsubstituted or halogen-substituted univalent hydrocarbon group with 1 to 10 carbon atoms, “a” is a positive number that satisfies the following condition:
• 1.9≦a≦2.2, and no less than 20 mole % of all R's in one molecule are phenyl groups, and (A2) an organopolysiloxane resin of an average unit formula:
• RaSiO(4-a)/2 wherein R is an unsubstituted or halogen-substituted univalent hydrocarbon group with 1 to 10 carbon atoms, “a” is a positive number that satisfies the following condition:
• 0.5≦a≦1.7, and no less than 20 mole % of all R's in one molecule are phenyl groups, wherein said mixture constituent (A1) is added in the amount of 99 to 30 wt. %, and said mixture constituent (A2) is added in the amount of 1 to 70 wt. %;
• (B) an organohydrogenpolysiloxane of an average unit formula:
• R1bHcSiO(4-b-c)/2 that contains in one molecule at least two silicon-bonded hydrogen atoms, wherein R1 designates an unsubstituted or halogen-substituted univalent hydrocarbon group with 1 to 10 carbon atoms, “b” and “c” are positive numbers that satisfy the following conditions:
• 0.002<c<1;
• 1.0<b<2.2;
• and 1.0<(b+c)<3.0 wherein said component (B) is added in such an amount that the mole ratio of said silicon-bonded hydrogen atoms of said component (B) to said unsaturated aliphatic groups of said component (A) is within the range of 0.3 to 5;
• 0.1 to 50 parts by weight of (C) a radical copolymer copolymerized from (a) a vinyl monomer that does not contain in its molecule an epoxy group, an alkoxysilyl group, and a hydrosilyl group, (b) a vinyl monomer having in its molecule an epoxy group and/or an alkoxysilyl group but not having a hydrosilyl group, and (c) a vinyl monomer having in one molecule a hydrosilyl group, said radical copolymer being copolymerized in the presence of (d) a chain-transfer agent;
• and a catalytic quantity of (D) a hydrosilation catalyst.