SEMICONDUCTOR DEVICE

PURPOSE:To enble secure connection with little contact bonding force and create only even and little stress inside the element, in connecting a circuit element to a mounting plate in face-down bonding structure. CONSTITUTION:A mounting plate 2 consists of an Si-plate 6, a buffer 18 of polyimide resin painted on the main surface, and an Au-Si-eutectic layer 9. A wiring layer 8 made of a gold-plating layer is formed on the top of the buffer 18. A connection electrode 14 corresponds to an electrode to be connected 13 of a circuit element 1. In case of connecting the circuit element to the mounting plate 2 by face-down bonding method, the electrode 13 and the electrode 14 are connected by pressing the former to the latter at 290 deg.C. Thereupon, the buffer 18 is softened by heat, and the buffer itself sinks partially at reception of intensive force as necessary, even if the surface of the electrode 13 or the electrode 14 is inadequate in flatness or uneven in thickness.