Investigation on damage behavior of lead-free solder joints based on finite element modeling

In this paper, regarding the joint interfacial zone as a special region with serious heterogeneity on microstructure and mechanical property, a creep-fatigue interaction damage model was proposed, in which two parameters named as creep strain energy density and average equivalent stress were introduced, aiming to reflect the effect of interfacial microstructure evolution. Based on the proposed heterogeneous research model and damage evolution equation, the damage evolution behavior and the effect of interfacial intermetallic compound (IMC) growth were studied based on finite element modeling (FEM). The results showed that, the accumulated damage in the solder joint increased with the increase of thermal cycles. The failure mode exhibited as that failure site was close to solder/intermetallic compound (IMC) interface, and the thicker the IMC layer, the more accumulated damage per cycle in the solder joint. These results demonstrate that IMC impacts solder joint reliability, and the bond at interfacial IMC/solder interface is most vulnerable to thermal fatigue damage.