The method of calculating the connection conditions of the semiconductor device

Solder is connected to the electrodes of the circuit board by using a temperature profile with a constant fusion temperature, a connection interface strength evaluation test is carried out on the soldered joints to obtain an appropriate reflow range free of decreases in the strength at the connection interface. On the basis of the appropriate reflow range obtained and using as the basis the chemical compound thickness which is determined uniquely by heat load, an appropriate reflow range in an optional temperature profile with one temperature peak is obtained. By carrying out connection in this appropriate reflow range, soldered joints can be obtained without decreases in the connection interface strength in the large-scale production stage.