Corrosion Behavior of Sn-1Ag-0.5Cu Solder Alloy with the Addition of Fe and Bi

Abstract

The needs for lead free solders have risen over concerns about the toxicity of Pb particularly to the public health and the environment. In line with current technological developments, the use of electronics has expanded to various applications such as industrial and automotive applications. This demands a higher reliability and durability of the device in more challenging operating environments that includes corrosive medium and moisture. In this work, we prepared Sn-1Ag-0.5Cu (SAC105) lead-free solder alloys with the addition of iron (Fe) and bismuth (Bi) and extensively investigated their corrosion behavior and microstructures. To characterize the corrosion behavior, combinations of physical (weight loss) and electrochemical tests (potentiodynamic polarization and impedance spectroscopy) were carried out in 0.1M NaCl solution, for various periods of time. In order to mechanistically understand the corrosion behavior of the solder alloys, an understanding of the microstructure is important as the alloying elements dictate the type of microstructure that is present within an alloy. The microstructural characterization and damage accumulation were executed by means of field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The correlation between electrochemical measurements and microstructural characterizations were made to clarify and quantify the overall performance of the SAC105 with addition of Fe and Bi.