Provided is a semiconductor device of improved reliability and ease of assembly associated with the downsizing thereof, in which a long shelf life of a solder joining a lead frame having a large current capacity and efficient release of heat from the lead frame can be achieved. In the semiconductor device, electronic components (23, 24) on an insulating substrate formed with a metal layer configuring a conductive pattern (12) are electrically connected to each other by a rectangular lead frame (22). In so doing, the lead frame (22) can correctly be positioned by inserting a wire member (27), which is disposed so as to bridge between the electronic components (23, 24), into an opening (21) formed to penetrate through the lead frame (22). Solder plates (28, 29) are sandwiched, respectively, between the electrode surfaces of the electronic components (23, 24) and joints (22a, 22b) of the lead frame (22), and are melted in a subsequent reflow step. The solder plates (28, 29) are provided with slits (28s, 29s) that are sized corresponding to the width of the opening (21) of the lead frame (22).