Thermally conductive composition, thermally conductive sheet obtained from same, and production method therefor

Abstract

Provided is a thermally conductive composition that contains a matrix resin made of a thermosetting resin, a curing catalyst, and thermally conductive particles. The thermally conductive particles include the following (a) to (c) with respect to 100 parts by mass of the matrix resin: (a) 600 to 1500 parts by mass of spherical alumina with an average particle size of more than 100 μm; (b) 100 to 400 parts by mass of alumina with an average particle size of 1 μm or less; and (c) 500 to 1500 parts by mass of aluminum nitride with an average particle size of 0.8 to 150 μm. A degree of plasticity of the thermally conductive composition after defoaming and before curing is 80 or less. With this configuration, the thermally conductive composition maintains a high thermal conductivity after curing and has a low degree of plasticity and good moldability. Further provided is a thermally conductive sheet formed using the thermally conductive composition and a method for producing the thermally conductive-sheet.