EFFECT OF INTERFACE ROUGHNESS ON FATIGUE-CRACK GROWTH IN SN-PB SOLDERJOINTS

The effect of interface roughness on fatigue crack growth was studied by examining the contribution of crack-surface sliding to the fatigue crack growth resistance of the interface in 63Sn-37Pb solder joints. M odel interfaces with different values of roughness were produced in Sn -Pb/Cu joints by systematically varying the morphology of the intermet allic phase at the interface. Fracture mechanics analysis was conducte d to calculate the crack-sliding resistance as a function of interface roughness, contact zone length, the shear strength of the solder, and elastic properties of bi-materials. The results were compared to the variation of fatigue crack growth threshold with interface morphology.