Effect of addition Zinc in Tin-Copper lead free solder on corrosion study in chloride solution

Sn-0.7Cu lead free solder has become an alternative material to replace Sn-Pb solder. However, it has disadvantages of high melting point and poor corrosion behavior. Through this study, corrosion rate and corrosion behavior of Sn-0.7-xZn in 3.5 wt.% sodium chloride (NaCl) solution was studied through open circuit potential analysis (OCP). The changes in structural, microstructure and melting temperature in Sn-0.7Cu after alloying with different concentration of zinc (Zn) was also discussed in this study. The result shows indication of a new phase, Cu5Zn8 is appeared after the addition of Zn into Sn-0.7Cu with scanning electron microscope (SEM) and x-ray diffraction (XRD). Moreover, the microstructure of Sn-0.7CuxZn is refined and melting point was decreased from 226.06 to 221.09 ºС after Zn has added. Through OCP analysis, Sn-0.7Cu has active electrochemical reaction within 3 hours with continuous increase in potential value. However, Sn-0.7Cu-0.25Zn shows the lowest potential value in OCP, -464 mV which indicates its corrosion rate was the highest. In addition, the behavior of Sn-0.7Cu-xZn can be further studied via polarization test in order have deeper understanding in its corrosion reaction.