Abstract: A semiconductor device according to the present invention includes a substrate made of an electrically insulative material having a relatively high thermal conductivity, a metallic pattern member provided on one major surface of the substrate and having an external terminal portion extending from the substrate, a semiconductor element mounted on the metallic pattern member, a metallic layer provided on the other major surface of the substrate, a heat dissipation plate fixed onto the metallic layer, and a mold body for coating both the substrate mounted with the semiconductor element and the heat dissipation plate so as to expose the external terminal portion.

Abstract: A resin-seal type semiconductor device includes a main substrate divided into first and second surfaces on which first and second insulating substrates are respectively provided. Circuit wiring patterns and first end portions of outer leads are provided on the first and second insulating substrates. Semiconductor elements are soldered onto the wiring patterns and coated with a surface protection material. The main substrate is then folded over so that the first and second surfaces oppose one another and the device acquires a U-shaped cross-section. A space formed between the first and second surfaces inside the U-shape is sealed with a resin such that second end portions of the outer leads are exposed from the resin.