Composite plating of Sn–Ag alloys for Pb-free soldering

The existence of Ag nanoparticles in the Sn–Ag composite plating electrolytes was confirmed from the UV–vis spectra using the surface plasmon peak. Wetting speed of the molten Sn–Ag solder to the Sn–Ag alloy-plated specimen by the composite plating was higher than that to the Sn-plated one. Solder bond strength of the Sn–Ag alloy-plated specimen was not decreased after the exposure to the humid environment, and was increased by the Ni underlayer.