Synergistic effect of thermomigration and electric current stressing on damping capacity of Sn58Bi solder

In order to evaluate the vibration resistance of Sn58Bi solder in serving electronic devices, the damping capacities of Sn58Bi solders after thermomigration (TM) test at a temperature gradient of 2000 degrees C/cm for different time (0, 120, 360, 720, and 1440 h) were characterized under electric current stressing (0, 4.0, and 8.0 A). The results indicate that the phase segregation of TM-tested Sn58Bi solders determines the damping performance of solders. The Bi-rich layer thickens with prolonged TM time and migrates in the direction from high temperature to low temperature. Both the critical strains (the values of dislocation getting rid of pining points) of strainamplitude-related damping capacity curves increases with prolonged TM time, while decreases with increasing electric current. Moreover, both strain-amplitude-related and temperature-related damping capacity shows a general decreasing trend with prolonged TM time, while increases exponentially with increasing electric current. In addition, the damping mechanism changes from dislocation motion to phase boundary sliding with increasing temperature, and the transition temperature decreases with increasing current but generally increases with TM time.