| 摘要 |
An epoxy resin composition comprising an epoxy compound represented by the formula (1): wherein Ar1, Ar2 and Ar3 each denotes any one of divalent groups represented by the following formulas: a curing agent and an alumina powder, wherein the alumina powder is a mixture of an alumina (A) having D50 of 2 mum or more and 100 mum or less, an alumina (B) having D50 of 1 mum or more and 10 mum or less, and an alumina (C) having D50 of 0.01 mum or more and 5 mum or less, in which D50 is a particle size at 50% cumulation from the smallest particle side of a weight cumulative particle size distribution, and the content of the alumina (A), that of the alumina (B) and that of the alumina (C) are respectively 50% by volume or more and 90% by volume or less, 5% by volume or more and 40% by volume or less, and 1% by volume or more and 30% by volume or less, based on the volume of the alumina powder (provided that the total % by volume of the alumina (A), the alumina (B) and the alumina (C) is 100% by volume).
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