Curable silicone resin composition with high reliability and optical semiconductor device using same

A curable silicone resin composition comprising:

• (A) an alkenyl group-containing organopolysiloxane, comprising an organopolysiloxane
• (A1) represented by an average composition formula (1) shown below and containing at least two alkenyl groups per molecule:
• (R1SiO3/2)a(R22SiO)b(R3R42SiO1/2)c (1)
• wherein
• R1 represents an alkyl group of 1 to 10 carbon atoms,
• R2 represents an aryl group of 6 to 14 carbon atoms,
• R3 represents an alkenyl group of 2 to 8 carbon atoms,
• each R4 independently represents an alkyl group of 1 to 10 carbon atoms or an aryl group of 6 to 14 carbon atoms,
• a represents a number of 0.2 to 0.6, b represents a number of 0.2 to 0.6, and c represents a number of 0.05 to 0.5, provided that a+b+c=1.0,
• (B) an organohydrogenpolysiloxane represented by an average composition formula (2) shown below and containing at least two silicon atom-bonded hydrogen atoms per molecule:
• in an amount that yields a molar ratio of silicon atom-bonded hydrogen atoms within the component (B) relative to alkenyl groups bonded to silicon atoms that exist within the composition of 0.4 to 4.0:
• R1dR2eHfSiO(4-d-e-f)/2 (2)
• wherein R1 and R2 are as defined above, d represents a number of 0.6 to 1.5, e represents a number of 0 to 0.5, and f represents a number of 0.4 to 1.0, provided that d+e+f=1.0 to 2.5, and
• (C) a catalytically effective amount of an addition reaction catalyst.