To solve a matter that an Si chip must be mounted as close as possible to the heat dissipating portion in order to enhance heat dissipation properties of a semiconductor module and an insulator is required between the Si chip and the heat dissipating portion in order to insure high breakdown voltage, but when solder is employed for bonding them, thermal fatigue of solder due to temperature variation during use must be prevented.

Warpage of a semiconductor module due to contraction of resin or the coefficient of thermal expansion can be lessened by mounting an insulating substrate mounting an electric circuit such as an Si chip on two or more sides of a heat dissipation plate and then molding the entirely of hard resin. Furthermore, heat dissipation properties can be enhanced by providing a channel of cooling liquid in the heat dissipation plate.