Development of High Temperature Lead-free Solders in the Al-95Zn + xSn Systems

The high-temperature lead-free solder alloys of Al-95Zn with the modification of the addition of Sn have been investigated. Its proportion is used to adjust the metallographic microstructure, solidified precipitate phase, and liquidus temperature of the solder alloy. The characterization results, such as scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and differential scanning calorimeter (DSC), will be discussed in this study. The study results show that the Al-Sn-Zn-based alloy has (Zn)+β- Sn+(Al) precipitates when heat-treated at 900°C for 36 h. Its liquidus temperature of Al-95Zn + xSn is between 342-385°C, and increased Sn content will decrease its liquidus temperature.