PURPOSE: To make possible the connection of a semiconductor device, which does not depend on a flux-containing solder, and to dispense with a cleaning process and heating by a method wherein the surface, on which a conductive metal film is formed, of the external lead-out lead of the semiconductor device and the surface, on which a conductive metal film is formed, of an electrode on a mounting substrate are brought into contact to each other and are welded by an ultrasonic vibration.

CONSTITUTION: In a semiconductor device connecting method wherein an external lead-out lead 13 with a conductive metal first film 15 formed on its surface led out outside of a semiconductor device 11 is connected with an electrode 17 with a conductive metal second film 18 formed on the surface of the electrode provided on a mounting substrate 16, the surface, on which the film 15 is formed, of the above lead 13 and the surface, on which the film 18 is formed, of the above electrode 17 are brought into contact to each other and are welded by an ultrasonic vibration. For example, the above films 15 and 18 are constituted of some one of indium and an indium alloy. Moreover, after an ultrasonic vibrator 19 is abutted on the upper part of a lead connecting part 14 aligned, the vibrator 19 is made to vibrate in a state that the vibrator is pressingly contacted to the connecting part 14 and the films 15 and 18 are soldered by the vibration energy.