Formation of solder bump

Abstract

Abstract PURPOSE:To place a core ball in complete correspondence with a pad and to improve positional accuracy, by forming a multiplicity of core balls coated with solder at positions of a copper foil where apertures are provided, thermally welding the core balls with each core ball positioned on a pad on a substrate and peeling off the copper foil. CONSTITUTION:A copper core 2, a diffusion preventing layer 3 and a solder coat 4 are formed by plating at each of a multiplicity of locations on a copper foil 1 where bumps are to be provided by photolithography, so that a solder bump sheet including core balls having a shape of round screw is produced. A substrate 5 is heated to melt the solder coat 4 and to weld the core ball. The copper foil 1 is tore at the sections connecting the bumps. In this manner, the core balls can be placed in complete correspondence with the pads 6 and the positional accuracy can be improved.

Inventors

• 👤 Ichiro Munakata
• 👤 一郎 宗像

Bibliographic Details