Evaluation of lead-free soldering for automotive applications

摘要

Studies have been conducted worldwide in order to find solder alloys able to replace the conventional SnPb eutectic. The SnAgCu eutectic seems to be one of the best candidates. However, during a transition period lead-containing and lead-free component finishes will be mounted with lead-free solder paste on the same board. So, components with three different finishes (tin-lead, pure tin and gold) were mounted on high T_g epoxy-glass PCB using a specially designed SnAg4Cu0.5 solder paste. Cross-sections were made on as reflowed and aged (-25℃/+150℃ thermal cycles, 2095 hours spent at 150℃) solder joints in order to observe their microstructure and analyse the interfaces.