Thermosetting epoxy resin composition and semiconductor device

A thermosetting epoxy resin composition comprising

• (A) a reaction mixture of a triazine derivative epoxy resin and an acid anhydride at a ratio of the epoxy group equivalent to the acid anhydride equivalent of 0.6 to 2.0;
• (B) an internal mold release agent;
• (C) a reflective material;
• (D) an inorganic filler;
• and
• (E) a curing catalyst;
• wherein the internal mold release agent of component (B) comprises in combination a carboxylate ester represented by the following general formula (1):
• R11—COO—R12 (1)
• wherein R11 and R12 are independently an alkyl group represented by CnH2n+1, and n is a number of 1 to 30 and a compound represented by the following general formula (2):
• wherein R1, R2, and R3 are independently selected from H, —OH, —OR, and —OCOCaHb with the proviso that at least one of the R1, R2, and R3 includes —OCOCaHb;
• R is an alkyl group represented by CnH2n+1 (wherein n is an integer of 1 to 30), a is an integer of 10 to 30, and b is an integer of 17 to 61.