Abstract
Tin based solders are being considered as substitutes for conventional Pb based analogues. The possibility of solder joint failure during service of electronic packages as a result of creep caused by heating is investigated in the present study by the impression creep of eutectic Sn - 3.5Ag, Sn - 0.7Cu and Sn - 9Zn alloys in the temperature range 303 - 439 K and in the stress range 21 - 148 MPa. The power law stress exponent values vary from 3.5 to 6.5. The activation enthalpy for Sn - 3.5Ag was found to be stress independent with an average value of 41 kJ mol-1. The activation enthalpies for Sn - 0.7Cu and Sn - 9Zn showed moderate stress dependence with zero stress activation enthalpies of 52 and 74 kJ mol-1, respectively. The steady state impression velocity varied linearly with punch diameter for all three alloys. The experimental results support dislocation climb as the rate controlling mechanism.
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