Thermally conductive silicon oxide compositions and their cured products and manufacturing methods

Abstract

This invention provides a thermally conductive silica composition with excellent preservation and thermal conductivity, comprising: (A) an organopolysiloxane (but, component (D) is removed), (B) spherical alumina powder with an average particle size of 50-170 μm and an average sphericity of 0.8 or more and hydroxyl groups of 30 or less per nm², (C) spherical or irregularly shaped alumina powder with an average particle size of 0.1-5 μm, (D) a silane coupling agent, and (E) a cation-exchange type and / or two-ion-exchange type ion scavenger, and having an ion scavenger supported on one or more elements selected from Zr, Bi, Sb, Mg and Al: the amount of the ion scavenger is 0.01-10 parts by mass relative to 100 parts by mass of component (A), and the volume ratio of component (B): (C) is 5:5 to 9.5:0.5.