NASA’s earlier lead-free solder high-reliability testing effort helped shed light on the reliability of circuit cards manufactured with lead-free solders. However, that project was not able to explore fully rework and mixed solder alloys. As the transition to lead-free becomes an ever-closer reality for military and aerospace applications, it will be critical to understand fully the implications of rework and mixed solder alloys. This joint project of Department of Defense (DoD), NASA and defense and space contractor representatives built on the results from the former NASA-led lead-free solder project; Joint Council on Aging Aircraft/Joint Group on Pollution Prevention (JCAA/JG-PP) Pb-free Solder Project. The new effort focused on the rework of tin-lead and lead-free solder alloys and included the mixing of tin-lead / lead-free & lead-free/ tin-lead solder alloys.
In response to concerns about risks from lead-free induced faults to high reliability products, NASA outlined a multi-year project to provide manufacturers and users with data to clarify the risks of lead-free materials in their products. The primary technical objective of the project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of packages (e.g., Thin Small Outline Package, Ball Grid Array, Plastic Dual Inline Package) assembled and reworked with lead-free alloys and with mixed (lead/lead-free) alloys. The assembled hardware were subjected to a variety of accelerated testing (e.g., thermal, vibration, combined environments, salt fog/humidity) to understand solder joint reliability. Data generated from this project is required to gain a better understanding of how lead-free electronics will perform in high-reliability aerospace applications. This project will provide baseline data for aerospace and defense (high-performance) applications.
