Effect of Thermal-Shearing Induced Microstructural Coarsening on SnAgCu Microelectronic Solder

Abstract

The creep response of solder joints in a microelectronic package, which are subjected to aggressive thermal-shearing cycling during service, often limits the reliability of the entire package. Furthermore, during cycle, the microstructures of the new lead-free solders (Sn-Ag-Cu) can undergo significant in strain-enhanced coarsening, resulting in in-service evolution of the creep behavior. In this paper, the coarsening kinetics of Ag3Sn particles in Sn-Ag-Cu solder are studied, and the results are correlated with impression creep data from individual microelectronic solder balls subjected to thermal aging treatments. The formation mechanism of Ag3Sn particles under the thermal-shearing cycling condition was investigated.