Void-free solder joint of semiconductor die on substrate - by precoating die back surface with solder to form dome surface and attaching die by placing on substrate

摘要

Soldering of a semiconductor die onto a substrate features precoating of the die-surface to be soldered onto with solder at such a temp that a domed solder surface is formed. The die is then placed on the substrate, touching this with the top of the dome. The soldering operations are pref carried out in a reducing ambient. The substrate used is pref Cu, the surface on which the die is to be attached is pref roughened by etching and Ni-coated. The solder used is pref a SnPb- alloy. USE/ADVANTAGE - The presence of the dome allows a joint to be made without including gas evolved during the soldering operation. This allows solder joints to be made without voids. The process is used for the assembly of die of power semiconductor devices.