"Description will now be made on the preferred embodiments in connection with the accompanying drawings, in which: FIG. 1 is a schematic cross-sectional diagram for illustrating a conventional method of soldering a semiconductor plate to a metal substrate with solder; FIGS. 2a and 2b are a schematic plan and a schematic cross-sectional diagrams for illustrating an embodiment of a method of solderin" . . . .