AMORPHOUS SILICEOUS POWDER, PROCESS FOR PRODUCTION THEREOF, RESIN COMPOSITION, AND SEMICONDUCTOR ENCAPSULATION MATERIAL

摘要

A semiconductor encapsulation material which exhibits a low viscosity and further improved moldability in encapsulation even when highly loaded with an inorganic filler; an amorphous siliceous powder suitable for the preparation of a resin composition useful as the encapsulation material; and a process for the production of the amorphous siliceous powder. An amorphous siliceous powder having a content of Si and Al of 99.5 mass % or above in terms of oxides, wherein the Al content in the particle size region of 15 μm to less than 70 μm is 100 to 30000 ppm in terms of oxides; the Al content in the particle size region of 3 μm to less than 15 μm is 100 to 7000 ppm in terms of oxides; and the Al content in the whole particle size region is 100 to 25000 ppm in terms of oxides. It is preferable that the (A)/(B) ratio of the Al content (A) in the particle size region of 15 μm to less than 70 μm to the Al content (B) in the particle size region of 3 μm to less than 15 μm be 1.0 to 20.