Modeling the effect of oxygen on the fatigue lifetime of solder joints

This paper deals with thermal fatigue of solder joints as function of oxygen concentration at the interconnection. Thermal fatigue occurs in the field as a result of computer on/off cycles, producing strains in the solder joints due to the thermal mismatch between the interconnected materials, i.e., chip and substrate. The time-to-failure increases with decreasing oxygen content, and is a function of shear strain, temperature, cycling frequency, geometry, stress relaxation, and process residues. The results help define design and application conditions for safe operation in the field and for the enhancement of the fatigue lifetime.