Effect of aluminum addition on the electrochemical corrosion behavior of Sn–3Ag–0.5Cu solder alloy in 3.5 wt% NaCl solution

The ternary eutectic Sn–Ag–Cu (SAC) solder alloys has become the most promising Pb-containing solders for the application in electronic packaging. The effect of Aluminum on the electrochemical corrosion behavior of Sn–3.0Ag–0.5Cu (SAC 305) solder alloy was investigated in 3.5 wt% NaCl solution in terms of potentiodynamic polarization and electrochemical impedance spectroscopy. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and atomic force microscopy (AFM) were used to characterize the samples after the electrochemical tests. Polarization studies indicated that an addition of 0.1 and 0.5 wt% Al in the Sn–3.0Ag–0.5Cu solder alloy shifted the corrosion potential (Ecorr) towards more negative values. The Impedance results revealed that the addition of Al with Sn–3.0Ag–0.5Cu solder alloy led to a lower corrosion resistance in terms of impedance values and the capacitance. The SEM images revealed existence of openings and pores in the corrosion product of solders containing Al. EDX and XRD analysis confirmed that the oxides and hydroxides of Sn and Al were the major corrosion products. AFM images exhibited that the surface becomes more rough and non-uniform with Al addition to SAC 305 solder alloy.