Minute copper balls and a method for their manufacture

摘要

Minute copper balls having a high sphericity which are suitable for use as the cores of copper core solder balls are manufactured by heating small pieces comprising an alloy of 0.5 - 40 wt% of Zn and a remainder of Cu to at least the melting point of Cu without the pieces contacting each other to give them a spherical shape and cooling the resulting spheres to form solid balls. The minute copper balls which are obtained comprises 0.01 - 0.5 wt% of Zn and a remainder of Cu and have a spherical shape with a diameter in the range of 50 - 1000 mu m.