Abstract:

The conversion from tin-lead to lead-free electronics has created concern amongst engineers about the reliability of electronic assemblies and the ramifications that reliability changes may have on the life-cycle cost and availability of critical systems that use lead-free electronics. In this paper the impact of lead-free solder on the repair of electronic assemblies subject to combined thermal and vibration loading is studied. The cost, repair time and availability of boards are quantified using a previously developed repair simulator for a test board developed and tested by the Joint Council on Ageing Aircraft & Joint Council on Pollution Prevention (JG-PP) that includes CLCC, TSOP, and PBGA packaged parts using tin-lead and lead-free solders. This paper describes the process of calibrating a physics-of-failure reliability simulator using experimental HALT test results for a specific board assembly and using the calibrated model to generate failure distributions corresponding to combined thermal and vibration loading over an actual product life cycle for use in the repair simulator. The results of the repair simulation indicate that longer dwell times appear to cause more damage than larger .T; under combined loading conditions, SnPb appears to be more reliable than SAC (for the board and parts considered in this study) and as a result, repair cost is lower; and the number of failures and repair times track repair costs (depending onthe capacity of repair process).

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