Abstract
Electrodeposited tin-zinc eutectic alloy is a promising candidate to replace tin-lead solder coatings and provide low temperature soldering. The eutectic alloy film (Sn-9.0Zn, mass%) of the desired constituent was deposited at cathode current density 0.5-3A/dm2 in a sulfosuccinate bath using the additive polyoxyethylene-α-naphthol (POEN) . The presence of POEN increased tin deposition polarization, markedly inhibited preferential deposition of tin over a noble potential range, and an appreciable amount of zinc was codeposition. The bath is stable systems, precipitate consisting of metastannic acid were not observed after standing for six months. The eutectic alloy film consists of β-tin and zinc phases, and its solidus temperature was 198°C. Whisker were not observed on the eutectic alloy film on the copper substrate after one year of aging at room temperature.
