Corrosion characterization of tin–lead and lead free solders in 3.5 wt.% NaCl solution

The corrosion resistance of Sn–Pb and several candidate lead free solders were investigated in 3.5 wt.% NaCl solution through potentiodynamic polarisation. Results showed that in NaCl solution lead free solders had better corrosion resistance than Sn–Pb solder and the corrosion resistance of lead free solders was similar, but the corrosion resistance of Sn–Ag solder was better than that of Sn–Ag–Cu and Sn–Cu solders. The corrosion products for Sn–Pb solder had a two-layered structure with Sn-rich phases at the outer layer and looser Pb-rich phases at the inner layer. The loose Pb-rich layer was detrimental to the corrosion property. The corrosion product on the surface of all these solders was tin oxide chloride hydroxide.