Study About the Corrosion of SAC Solder Joints Under Various Conditions of Temperature and Salinity

Abstract This study investigates the corrosion effects on SAC305 lead-free solder joints under varying temperature and salinity conditions. Researchers exposed chip resistors soldered with SAC305 on FR4 boards to salt spray environments at three temperatures (25, 35, and 45 °C) and three salinity rates (3.5%, 5%, and 6.5% NaCl). While no electrical failures occurred during testing, mechanical strength decreased significantly with increasing corrosion time, temperature, and NaCl concentration. Through optical microscopy and SEM-EDX analysis, the researchers identified that the corroded areas contained primarily Sn, O, and Cl-. By correlating shear force measurements with the percentage of corroded solder joint area, they established a failure criterion at approximately 61% corroded surface area. This criterion was validated with additional testing, providing a practical measure for predicting mechanical failure in SAC solder joints exposed to marine environments.