Patent ID: 8173053

Claim:
A white heat-curable silicone resin for forming optoelectronic part cases, comprising (A) a heat-curable organopolysiloxane having the average compositional formula (1): R 1 x Si(OR 2 ) y (OH) z O 4 - x - y - z y /2 (1) wherein R 1 is each independently an organic group of 1to 20carbon atoms, R 2 is each independently an organic group of 1to 4carbon atoms, x, y and z are numbers satisfying 0.8 <x <1.5, 0<y <0.3, 0.001 <z <0.5and 0.801 <x+y+z <2, (B) a white pigment, (C) an inorganic filler excluding the white pigment, and (D) a condensation catalyst, wherein a particulate mixture of the white pigment (B) and the inorganic filler (C) has a particle size distribution having maximum peaks in the three ranges of 0.4 to 1.0 μm, 8 to 18 μm, and 30 to 50 μm, said composition having a thermal conductivity of 1 to 10 W/mK.