Patent ID: 7825528

Claim:
An epoxy resin composition comprising an epoxy resin, a curing agent, and an inorganic filler, wherein: the epoxy resin is a modified epoxy resin prepared by glycidyl etherification of a mixture of: a novolac type phenolic compound having a biphenyl derivative in the molecule, represented by Formula 1: (wherein n is an average of 1 to 6); and a 4,4′-dihydroxy biphenyl compound, represented by Formula 2: (wherein R 1 , R 2 , R 3 and R 4 are hydrogen, alkyl, or aryl substituents or derivatives thereof), the curing agent is a mixture of: the novolac type phenolic compound having a biphenyl derivative in the molecule, represented by Formula 1 (wherein n is an average of 1 to 6); and a polyfunctional curing agent, the polyfunctional curing agent including a structure represented by Formula 3: (wherein n is an average of 1 to 6), and the inorganic filler has: a particle size distribution in which particles having a particle size of 53 μm or larger account for 0.3% by weight or less on a cumulative weight basis, an average sphericity of 0.85 or more, a mean particle size of 8.7 μm to 14.9 μm, and a particle size distribution in which particles having a particle size of 3 μm or smaller account for 15.4% to 23.4% and particles having a particle size of 24 μm or smaller account for 66.9% to 84.3%.