High‐Temperature Lead‐free Solder Materials and Applications

Summary

The increasing demand for solders to perform at high temperatures has necessitated the development of Pb‐free solders for high‐temperature applications to replace the high Pb‐bearing solders that are currently in use. The candidate Pb‐free solder should cover a spectrum of properties, which include suitable melting temperatures, suitable operating temperatures, microstructure stability, good wetting, excellent thermomechanical fatigue resistance, good thermal and electrical conductivities, and good corrosion resistance, along with having a low‐cost, nontoxic nature, and wide availability. This chapter provides a review of recent research on the current development of the Pb‐free solders for high‐temperature applications. It covers a wide variety of solder alloys including Zn‐based alloys, Bi‐based alloys, Au‐based alloys, as well as Sn‐based alloys with various modifications and additives to these alloys. It has been found that a single high‐temperature Pb‐free solder alloy cannot cover all the applications. However, some solder systems have the potential to cover some of the high‐temperature applications. The alternative solder alloys have been analyzed for their relative advantages and drawbacks. This chapter also specifies those Pb‐free solders that have potential for certain applications and identifies those areas where further research is needed.