Effect of material and geometry parameters on the thermo-mechanical reliability of flip-chip assemblies

Detailed models have been created to understand the effect of material and geometry parameters on die stresses and solder bump strains in flip-chip assemblies. The following parameters were considered: substrate thickness, die thickness, stand-off height, interconnect pitch, underfill CTE, underfill stiffness, solder mask stiffness and solder mask CTE. The stresses at the back of the die have been reported. Lifetime predictions for the solder bumps based on Coffin-Manson relations are also given