The reliability of aged and repaired lead-free and mixed lead-free/lead-based solder interconnects is an important issue for electronic equipment manufacturers. As a result of the global transition away from lead driven by government legislation and market pressure, maintained lead-based electronic equipment may need to be repaired with lead-free parts and materials due to improper labeling or inability to obtain proper replacement materials. An experimental study to examine the reliability of aged and repaired solder interconnects was conducted. Test specimens included thermally aged and non-aged lead-free and lead-based printed wiring assemblies with surface- mount components, including ball grid arrays (BGAs), leadless resistors, and quad flat packages (QFPs). Test specimens were subjected to aging and repair where lead-free and lead-based components and materials were intentionally mixed. Temperature cycle loading was used to examine the reliability of the solder interconnects. Test results show that thermal aging is more detrimental to lead-free solder interconnects than to lead-based interconnects for PBGAs. Further, the failure distribution of the lead-free assembled PBGAs was found to be wider than the distribution of the lead-based failures.
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