Effect of bismuth and silver on the corrosion behavior of lead-free solders in 3.5 wt% NaCl solution

Abstract

Electroanalytical tests were carried out to investigate the corrosion behavior of various lead-free solder alloys in 3.5 wt% NaCl bulk solution under room temperature. Scanning electron microscope (SEM) method was applied to investigate the corroded surface structure and corrosion depth using cross-sectional samples. Furthermore, energy dispersive spectroscopy (EDS) method was also applied to identify the chemical elemental composition of the corrosion products of the solders. The results showed that the bismuth and silver bearing solders have lower corrosion resistance compared to other lead-free solders and to the widely used SAC305 as well. The different corrosion resistance was explained by the different silver and bismuth content and volume of the corrosion products, which can lead back to the differences of the original alloying components. This study is highlighted that the bismuth and silver content may pose a relative high corrosion risk related to lead-free solder alloys used in electronics.