The electronics industry’s transition to lead-free soldering has been characterised by misapprehensions about the properties that are important in a lead-free solder and about the consequences for soldering processes and solder joint reliability. In this article the realities that have emerged from the practical implementation of lead-free soldering are reviewed and their implications for alloy selection considered. Particular attention is given to the benefits of replacing tin-lead, which behaves as near perfect eutectic, with lead-free solders that also behave as a eutectic.

Keith Sweatman is a graduate in metallurgical engineering who had his first exposure to soldering technology when he opened an Australian office of the organisation then known as the International Tin Research Institute (now Tin Technology). He took the knowledge gained in that organisation to Multicore Solders Ltd where he started as technical manager for their Asia Pacific operations and ended up as Multicore Solders Asia Pacific Region managing Director. Since 2001 he has been assisting Nihon Superior in the development of their global lead-free solder business.