Patent ID: 7671453

Claim:
A semiconductor device in which chips are resin-molded, comprising: frames having die pads including front and back surfaces; power chips mounted on the front surfaces of the die pads; an insulation resin sheet having first and second surfaces on opposite sides of said insulation resin sheet, the insulation resin sheet being disposed such that the back surfaces of the die pads contact the first surface of the insulation resin sheet; a mold resin applied on the first surface of the insulation resin sheet so as to seal up the power chips; a mixture layer formed on the first surface of the insulation resin sheet where the insulation resin sheet contacts the mold resin and formed of a mixture of said insulation resin sheet and said mold resin; and a metal foil disposed on the second surface of the insulation resin sheet, wherein the thermal conductivity of the insulation resin sheet is at least twice as large as that of the mold resin, and wherein the mixture layer results from contacting the insulation resin sheet in a molten state with the mold resin in a molten state.