Patent ID: 7943706

Claim:
An epoxy resin composition used for encapsulation of a semiconductor device comprising a resin substrate or a metal substrate and a semiconductor member mounted solely on one surface of the resin substrate or on one surface of the metal substrate, wherein the semiconductor member is encapsulated solely on the one surface of the resin or metal substrate with a cured product of an epoxy resin composition comprising (A) an epoxy resin comprising (a) a naphthalene ring-containing epoxy resin having an epoxy equivalent of 175 to 210, the naphthalene ring-containing epoxy resin being a mixture of the following epoxy resins (i), (ii), and (iii): wherein R is hydrogen, C 1 -C 4 alkyl, or phenyl, and G is a glycidyl-containing organic group, with the proviso that 45 to 70 parts by weight of the epoxy resin (i) and 5 to 30 parts by weight of the epoxy resin (iii) are included per 100 parts by weight of the mixture, with the remainder of the mixture being epoxy resin (ii), and the naphthalene ring-containing epoxy resin (a) comprises 100% by weight of the entire epoxy resin component (A), (B) a phenolic resin comprising (b) a naphthalene ring-containing phenolic resin having the following formula (4): wherein n is an integer of 0 to 10, and the naphthalene ring-containing phenolic resin (b) of formula (4) comprises 100% by weight of the entire phenolic resin component (B) in such an amount that the molar ratio of phenolic hydroxyl groups in the curing agent to epoxy groups in the epoxy resin is from 0.5 to 1.5, and (C) an inorganic filler in an amount of 200 to 1100 parts by weight of the epoxy resin (A) and curing agent (B) combined, wherein the substituted or unsubstituted naphthalene ring of the epoxy resin (a) is contained in an amount of 45 to 60% by weight in the total amount of the epoxy resin (A).