Solderability of Sn–9Zn–0.5Ag–1In lead-free solder on Cu substrate: Part 1. Thermal properties, microstructure, corrosion and oxidation resistance

The thermal properties, microstructure corrosion and oxidation resistance of the Sn–9Zn–0.5Ag–1In lead-free solder have been investigated by differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersive spectrometry, potentiostat and thermogravimetry. The Sn–9Zn–0.5Ag–1In solder alloy has a near-eutectic composition, it melts at 187.6 °C and the heat of fusion is determined as 71.3 J/g. The Sn–9Zn–0.5Ag–1In solder alloy with a corrosion potential of −1.09 VSCE and a current density of 9.90 × 10−2 A/cm2, shows a better corrosion resistance than that of the Sn–9Zn solder alloy. From the thermogravimetry analysis, the weight gain ratio of the Sn–9Zn solder alloy appears a parabolic relationship at 150 °C. The initial oxidation behavior of the Sn–9Zn–0.5Ag and Sn–9Zn–0.5Ag–1In solder alloys also shows a parabolic relationship but the weight gain ratio of them appears a negative linear one after aging at 150 °C for 2.5 and 5 h, respectively.