Solder joint properties of Sn-Ag-Cu solders on environmental-friendly plasma surface finish

Plasma coating for the surface finish of PCBs is a potential replacement of the conventional PCB finishes because of its environment-friendly process which does not produce any waster solution. In addition, the plasma surface finish enables to perform the multiple soldering over 5 times and shelf life is over 1 year. Corrosion properties of the plasma surface finish is higher than that of conventional surface finishes. In this study, solder joint properties were examined to understand the reliability of the plasma surface finish. Plasma surface finish was basically fluorine-based organic-inorganic composite thin films, which were deposited onto the Cu pads of a PCB. Sn-3.0Ag-0.5Cu (SAC305) solder was used as solder joint materials. Solder joint strength of the plasma finish sample was similar to that of the OSP finished sample. Plasma finishes had slightly higher brittle fracture rate after the multiple reflow test than OSP finish. In addition, plasma finish had higher corrosion resistance than OSP after a salt spray test.