High-Temperature Lead-Free Solder Alternatives: Possibilities and Properties

High-temperature solders have been widely used as joining materials to provide stable interconnections that resist a severe thermal environment and also to facilitate the drive for miniaturization. High-lead containing solders have been commonly used as high-temperature solders. The development of high-temperature lead-free solders has become an important issue for both the electronics and automobile industries because of the health and environmental concerns associated with lead usage.

Unfortunately, limited choices are available as high-temperature lead-free solders. This work outlines the criteria for the evaluation of a new high-temperature lead-free solder material. A list of potential ternary high-temperature lead-free solder alternatives based on the Au-Sn and Au-Ge systems is proposed.

Furthermore, a comprehensive comparison of the high-temperature stability of microstructures and mechanical properties of these potential candidate alloys with respect to the currently used high-lead content solders is made. Finally, the paper presents the superior characteristics as well as some drawbacks of these proposed high-temperature lead-free solder alternatives.