Influence of different surface finishes of PCB on the solder spread

Monitoring of the solder spread is one of the tools which should be used to solderability and wetability quantification. In this paper we focus on the different solder spread in correlation with different surface finishes of the PCB and different type of reflow process. In our experiment we used three types of solder pastes (one lead Sn62Pb32Ag2 and two lead free Sn95,5Ag4Cu0,5, Sn99,25Cu0,7Ni0,05 solders) and four types of surface finishes of PCB (lead free H.A.L., pasivated cooper, immersion tin plating, chemical gold plating) and we used two types of reflow processes - vapor phase reflow process and continuous hot air reflow process. Solders spreading area was evaluated by image analysis.