. "ectrode being formed on a terminal portion are made up of a metal having a high melting point and an alloy mainly containing Al being excellent in pitting corrosion and being formed and stacked in a layer on the alloy having a high melting point. [0099] In the foregoing, a preferable mode is one wherein an element or elements to be added to the alloy containing mainly Al include any one of Nd, Ti," . . . .