Design and assembly process effects on lead free solder joint reliability of bare die and lidded flip chip ball grid array packages

Board level temperature cycle and drop test reliability data was collected for 23 × 23 mm FCBGA packages. Two different bare die thicknesses, the effect of lidded configuration, and two different board thicknesses were evaluated as key design factors. Different package warpage shapes modulated by two different assembly process flows, two different ball attach reflow profiles and ball attach rework were evaluated as key package process parameters. Two temperature cycle conditions were applied including JESD22-A104D Condition G and Condition N. Drop-shock test was also performed under JESD22-B104C Condition A and Condition B. The data suggested that bare die thickness and lidded configuration had significant impact on both temperature cycle and drop test reliability while the process parameters studied did not have a statistically significant effect. Composite substrate and board mechanical properties were characterized. Finite element analysis was conducted to interpret temperature cycle solder ball failure location considering both peeling stress and inelastic strain energy density.