Influence of Humidity on Voids Formation Inside the Solder Joint

Abstract

Void is defined such as blow hole in the solder joint. Voids may degrade the mechanical and conductive properties of the solder joint and thus decrease the reliability. Article deals with influence of humidity on voids formation inside the solder joint structure. Experimental part was carried on testing samples, where we used three types of solder pastes (Sn62Pb36Ag2, Sn96.5Ag3Cu0.5 and Sn95.5Ag4Cu0.5), three types of reflow technology (hot air, vapor phase and infra radiation reflow technology) and three types of humidity environments. The inspection was made on X-ray and following diagnostic was made by image analysis with special software. We evaluate the number of voids together with their total area of all voids inside solder joints. Results indicate that the number of voids together with their total area mainly depends on type of used solder paste. Dependence of used reflow process on voids formation is minor and the influence of components humidity on voids formation wasn’t observed.