Abstract: In order to resolve the problems of low soldering efficiency and high void ratio in power modules, the solder type, vacuity and void ratio were investigated, and a new fluxless vacuum soldering process using plasma cleaning was presented. The results show that the vacuum pumping rate is increased and the void ratio is decreased obviously using solder sheet and plasma cleaning technology. The new soldering process with low void ratio, high efficiency and high quality conformance can be used in the soldering of high reliability power electronics.

Key words: Plasma cleaning, Fluxless, Void ratio, Vacuum soldering, Solder sheet