Surface finish influence on PCB contamination by flux spattering effect

Flux spattering effect can appear during the manufacturing assembly process, especially during reflow process, when the solder paste, which contains flux, is heated and the flux is spattered and contaminate surroundings. This effect mostly happened due to moisture absorption by the solder paste or due to improperly temperature profile settings during the reflow process. Spattered residues of flux have a non-conductive character and therefore it caused a problem in quality testing of the product, especially when a spot of flux reside appear on the PCB testing pad than the in-circuit test marked tested product as the bad one even though that it is a good one. This article deals with influence of surface finishes on flux spattering effect. Two solder pastes (Sn95.75Ag0.75Cu3.5 and Sn96.5Ag0.5Cu3 contains flux type ROL0) and four types of surface finishes (passivated cooper, hot air leveling, immersion tin, ENIG) were used in our experimental study.