A preliminary solder joint life prediction model by experiment and simulation for translation of use condition to temperature cycling test condition

This paper introduces a new preliminary solder joint fatigue model based on thermo-mechanical finite element analysis (FEA) simulation results and the use of extensive solder joint reliability (SJR) experimental data for ball grid array (BGA) packages. A comprehensive FEA modeling method for temperature cycling (TC) loading was defined based on thorough and detailed convergence studies on modeling approaches, mesh sensitivities, analysis parameters, material parameters, boundary conditions and thermal loading conditions. Extensive reliability data was collected for various package designs, form factors, board thicknesses and testing conditions to demonstrate feasibility. The result is a solder joint fatigue model derived from FEA thermal mechanical modeling results and empirical reliability data regression fitting. Next, this FEA modeling method was coupled with a transient heat transfer method to integrate thermal gradients that exist in actual product use condition (UC) duty cycles. A new UC method is demonstrated based on a common physical damage metric calculated from numerical simulations for UC (with real user behavior data and temperature gradient) and TC (uniform temperature) conditions. The derived SJR fatigue model was combined with the newly developed UC method to establish new TC test requirements based on the actual use condition duty cycling.