Mechanical behaviors of 60/40 tin-lead solder lap joints

Creep-fatigue interactions have been shown to play a critical role in the failure of surface mount solder joints. Monotonic, fatigue, and creep-fatigue data for 60/40 tin-lead solder lap joints at room temperature are presented. Monotonic tests performed include rapid-strain shear, creep, and stress relaxation tests. Fundamental data for the strain range partitioning (SRP) approach to creep-fatigue life-prediction are presented. SRP is found to model adequately the solder creep-fatigue response for the range of frequencies (0.007 to 0.5 Hz) and waveforms tested. Instantaneous plastic strains and viscoplastic strains are found to be equally damaging, in any combination, for isothermal room-temperature creep-fatigue. Fatigue lives obtained for 0.5-Hz tests performed under load control correlate with the lives to 50% load drop obtained for tests performed under strain control.<>