IPC PERM 022:2018-08-01

Manufacturers of high reliability electronics have been working for many years to mitigate the deleterious effects of tin whisker formation. One highly effective means to suppress the growth of tin whiskers is to replace the pure tin plating with reowed tin-lead solder. One approach is to fully consume the tin plating by tin-lead solder during the SMT reflow process. This phenomenon of tin replacement during SMT reflow has been termed 'self-mitigation', because the components mitigate themselves without the need of any special additional processing. Self-mitigation has many advantages over other forms of tin mitigation as it is highly effective, adds no additional cost and subjects the components to no additional handling. A round robin study has been performed by IPC/PERM Task group 8-81, during which identical sets of test vehicles were assembled, in accordance with IPC J-STD-001, Class 3, at multiple locations. Results of this study are presented together with relevant conclusions and recommendations to guide high reliability end-users on the applicability and limitations of this mitigation strategy.