Impression creep of a Sn60Pb40 alloy: the effect of electric current

Solder joints provide electrical and mechanical interconnections in microelectronic circuits and devices. The mechanical behaviour of the solder joints plays an important role in determining the reliability and lifetime of microelectronic devices. Using the impression technique, the effect of electric current on the creep deformation of a Sn60Pb40 alloy was studied in the temperature range of 323-383K and under the punching stress of 9.7-110MPa. During the test, a constant dc electric current was passed through the sample, which introduced electromechanical interaction. A steady state creep was observed under the action of the dc electric current and punching stress. The steady state impression velocity increased with the increase in the electric current for the same punching stress, and the stress dependence of the impression velocity followed Eyring's relation. The apparent activation energy decreased linearly with the square of the electric current due to the increase in atomic mobility driven by the electric current.