An improved substructure method for prediction of solder joint reliability in thermal cycle

With the current trend of less expensive, faster, and better electronic products, it has become increasingly important to evaluate the IC package and system performance early in the design stage using simulation tools. For the solder joint subjected to cyclic stresses generated during the thermal cycling, its reliability depends on its resistance to creep and fatigue. The approach for simulation in this paper includes advanced finite element modeling with sub-structuring method. To simplify the analysis the temperature cycle is divided into different portions, and correspondingly the material properties are specified at that temperature range. The material properties are assumed to be linear and the equivalent elastic modulus corresponding to a specified temperature is got based on similar critical solder joint deflection. All non-critical solder joints with equivalent elastic modulus are condensed into a super-element with substructure analysis. At different temperatures, non-critical solder joints with specified equivalent elastic modulus are condensed in a serial of super-elements. To use different super-elements, windows batch command and ANSYS batch mode are used for automatic super-element generation and analysis.