Constitutive model and parameter identification for lead-free SAC305 solder

With the development of electronic industry, electronic packaging structures and systems are developing towards high miniaturization, integration, low power consumption and high reliability. The corresponding electronic packaging structure is more complex, and the serving conditions are increasingly challenging. Therefore, the study on the material properties and the corresponding constitutive model are of great values to describe the mechanical properties of solder joints for the numerical analysis of solder joint and the mechanical reliability of electronic packaging structures. In order to accurately reflect the deterioration of the mechanical properties of the solder joints under the service conditions subjected to thermal cycling, the numerical simulation of SAC305 solder was carried out at the both levels of material and solder joints. The unified creep and plasticity constitutive model was used to simulate the uniaxial tensile test data of SAC305 solder under different displacement loading rates. According to the published data of SAC305 solder uniaxial tensile test in the literature, the parameter identification method is proposed as follows: firstly, the fixing multiple parameters are used, and then the fitting effect of individual parameters on the experimental curve is studied, and finally all constitutive model parameters are identified. Moreover, the rationality of the constitutive model is verified by the electronic packaging structure. The results show that the optimized parameters can reasonably describe the mechanical behavior of solder joints under typical service conditions.