JPS5541720A - Preparation of stud base for semiconductor device - Google Patents

Abstract

PURPOSE: To provide a stud having an increased allowable fastening torque useful in a semiconductor device by preparing the stud following the soldering of a molybdenum plate and treating the stud material in the hardened state by an extruding machine.

CONSTITUTION: A prepared working material of composite metal 10 consisting of a thick layer 12 of a highly conducting metal, such as copper or zirconium steel, and overlying same a thin layer 14 of a highly weldable metal, such as nickel or cupronickel, is treated by punching into a disc-like shape, which is then applied on a backwardly extruding machine 22, to form a swelling 16 at the top and, at the same time, to have a polygonal configuration of the outer circumference. A ring-like protrusion 17 to which a shell is to be joined by projection welding is formed on the surface around the swelling 16. The upper surface of the swelling 16 is cut to form a level surface to expose the underlying metallic layer 12, while a molybdenum plate 18 is silver-sldered onto the levelled surface of the swelling 16. Finally, push the thus treated composite metal 10 further backward in the extruding machine 22, and there is formed a stud 30, the allowable fastening torque of which is much increased.

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