Effects of Substrate Surface Character on Tin Deposits of Pb-Free Electroplated Lead Frames

The effects of Cu substrate surface on tin deposits of Pb-free electroplated lead frames were examined.The SEM and XRD data show that the appearance of deposits depends on crystal structure.The XPS results indicate that the surface oxidation state of Cu lead frame has a great impact on the appearance of tin deposits.The tin deposits electroplated on Cu lead frame with CuO surface layer tend to exhibit black surface appearance.The deposits quality can be improved by strengthening descaling process before plating or increasing electrochemical polarization of the additive in the bath.