2008 Volume 49 Issue 7 Pages 1524-1530
Effect of holding time and temperature on the fatigue life of micro Sn-Ag-Cu solder joint has been studied with waveform of triangle and trapezoid wave at 298 K and 398 K. Both the microstructural coarsening and the crack propagation occurred simultaneously and therefore the cyclic load decreased rapidly in the trapezoidal wave at 398 K compared with the other conditions. Therefore, under the condition of waveform that includes holding time at high temperature, it is necessary to define fatigue life by considering crack length, although the load drop life definition is typically employed for the low cycle fatigue evaluation. The fatigue life of Sn-Ag-Cu micro solder joints is not strongly affected by temperature and holding time when the crack length is considered to define fatigue life. This is different form the trends in large scale bulk specimen and is attributed to the peculiar microstructure of the Sn-Ag-Cu.