Wetting and Interfacial Chemistry of New Pb-Free Sn-Zn-Ag-Al-Li (SZAAL) Solder with Cu, Ni, and Al Substrates

Abstract This paper presents the results of Ni substrate wetted with liquid Sn-Zn eutectic alloy addition Ag, Al, and Li (84.3 at.% Sn, 13.7 Zn, 1 0.5 Li-SZAAL). The wetting tests were performed using two methods: balance (WBT) sessile drop (SD) method at 250 °C, in presence an ALU33® flux. times 5, 20, 60, 180, 1800 s. Next, microstructure selected solidified solder joints was investigated scanning electron microscope. Ni-Zn system's intermetallic phases (IMCs) identified solder–Ni interface. kinetics formation growth IMC layer determined. Interfacial tension contact angle (CA) values calculated from WBT measurements compared to surface maximum bubble pressure CA those obtained SD method. value SZAAL on Cu (39°) is lower than (43°). For comparison, also interaction between measured. After s, IMCs thickness significantly reduced for pad substrate. study found that improved tensile strength wettability eutectic-based alloys.