SAE ARP6537

This document provides risk mitigation for Pb-free solders used internal to parts used in Aerospace and Defense applications. It will include mitigations applicable to encapsulated and cavity devices as the needs arise in industry. Currently this revision only addresses devices with encapsulation or underfill. Mitigations for open cavity devices are still being discussed, and will be addressed in future revisions. Microbumps with Thermal Compression Bonding (TCB) are not addressed by the mitigations in this document. The use of Pb-free microbumps with TCB are considered out of scope at this time. It is expected that this document will be primarily used by Control Levels 3 and 2C (as defined in GEIA-STD-0005-2 for programs that do not allow use of Pb-free tin or only allow its use on an exception basis). It may be used by other levels, or by applications not using GEIA-STD-0005-2. Piece part suppliers have been transitioning to using Pb-free solders within parts. However, aerospace and military programs are concerned about the risk from tin whiskers and the durability of these materials in their applications due to their special circumstances (see Introduction). This document will provide guidance on necessary tests and evaluations for parts using Pb-free solders to mitigate these risk concerns.