Criteria for Solder Alloy Adoption

ABSTRACT Solder is a critical component in modern electronic systems – past, present, and future. While solder is used within packaged electrical devices, the highest volume of solder is used for en-masse fabrication of printed circuit board assemblies. Historically, tin-lead solder was the dominate material used in printed circuit board assemblies. However, tin-silver-copper solder replaced tin-lead solder starting in 2006 after regulations banned the use of lead for a wide range of electronic products. Despite the successful transition to tin-silver-copper lead-free solder and over fifteen years of lead-free electronic production, a number of aerospace and defense products have not converted to tin-silver-copper or other lead-free solders over reliability concerns. Reliability should be a concern for all product manufacturers and end-users. This begs the question, what has convinced industries that are currently producing lead-free products that the reliability was sufficient and what is keeping defense and aerospace electronic equipment manufacturers from adopting lead-free solder. This paper reviews decision processes for adopting solder for printed circuit board assembly.