Electrochemical Corrosion Behavior of SnAgCu and SnPb Solder Alloys in Solution with Activator

The electrochemical corrosion behavior of lead-free Sn-3.0Ag-0.5Cu and Sn-37Pb solder alloys in 0.1 mol/L oxalic acid solution at 20 ℃ was investigated by potentiodynamic polarization method and compared with the results in 0.1 mol/L NaCl solution.The corrosion products were observed by SEM and the chemical components were examined by EDS and XRD.The results showed that Sn-37Pb solder had poor corrosion resistance compared with Sn-3.0Ag-0.5Cu in both two media.In oxalic acid solution two solders ethibited passivation,and the corrosion products were stannous oxalate mainly,the passivation mechanism of the solders accorded with the film forming theory.But there was no passivation phenomenon in 0.1 mol/L NaCl solution.