Corrosion behavior of lead-free SAC-type solder alloys in liquid media

New lead-free solders are developed for electronic assemblies as a replacement for traditional Pb-containing alloys. The main goal of this study was to investigate the corrosion resistance of ternary Sn-Ag-Cu (SAC) alloys in the air-saturated aqueous solutions of NaCl (including sea water) and containing NO 3 − , SO 4 2− , Cl − ions of concentration equivalent to those in acid rains. The Atomic Absorption Spectrometry (AAS) was used to determine Ag, Cu and Sn concentrations in the corrosive media. The corrosion potential and current were obtained using the potentiodynamic polarization technique. Corrosion resistance experiments of Sn-Ag-Cu alloys with the potentiodynamic method revealed that the solders were considerably resistant to corrosion in the liquid media used. The eutectic composition alloy was characterized by a higher resistance than the near eutectic one despite very small differences in the chemical composition. Corrosion rate during spontaneous dissolution was considerably lower than that derived from the potentiodynamic experiments because of blocking the reaction surface with corrosion products.