Geometrical size effect on interfacial diffusion of solder joint

In this study, two kinds of microscale solder joints, Sn-0.3Cu/Cu and Sn-0.5Cu/Cu, were studied. The element diffusion behavior at the soldering interface was investigated as the bulk solder size various from 5μm to 100μm during HTS (High Temperature Storage) aging. Experimental results indicated that the size and shape of solder joints have a significant effect on the element concentrations at the interface and the growth rate of interfacial IMC. With the decrease of the geometrical size of the bulk solder in Sn-Cu/Cu microscale solder joint, the concentration of interface element changed obviously until the bulk solder have been exhausted. Cu concentration in the solder near interface decrease when the volume of bulk solder increased. Therefore, at the the microscale concentration distribution of diffusion elements were influenced by the geometric size of microscale solder joints, which should be considered in reliability design of microscale solder joints.