Although the tin-zinc system has a eutectic at nine percent zinc that looks promising as the basis for a low melting point lead-free solder, so far only very limited success has been achieved in realizing that potential in commercial mass production. The problems that have limited the success of alloys based on this eutectic include their chemical reactivity, which tends to make it unstable in solder paste formulations, and its susceptibility to corrosion in service.
Options for enhancing the performance of alloys based around the tin-zinc eutectic include modification of the alloy with targeted dopants and formulating solder paste flux mediums that do not react with the alloy until the point of reflow. In this paper, the authors report work that has successfully addressed these issues to produce a solder that appears to have a real prospect of filling a well recognized gap in the application range of lead-free solders.