Mixed Alloy Soldering

摘要

My August 2005 column focused on backward-compatible, mixed-alloy (SnPb and lead-free) reflow soldering with a concentration on BGAs. While I would prefer to avoid this scenario altogether, I think it is unavoidable. As I stated, there will be an interim period where SnPb and lead-free alloys will coexist on the same PCBA and, in most cases, using lead-free components with SnPb solder will not cause soldering or reliability problems. Most lead-free surface finishes are backward-compatible with SnPb solder — with the exception of SnPb solder and lead-free BGAs, which is a risky combination.