Thermal fatigue life prediction for solder joints with the consideration of damage evolution

Thermal fatigue of solder joints is critical to electronic package performance and service life. It is well known that the fatigue life is rather difficult to estimate because of the complex interaction between creep and fatigue of solder materials. Conventional life prediction methods such as the Coffin-Manson relation or its modifications may give erroneous results at the low strain range. In this paper, a nonlinear finite element based model is introduced for prediction of the thermal fatigue life of solder joints. This method not only considers the solder damage evolution, but also saves substantial computational effort. In this model, the damage evolution is determined by the collapse of shear stress-strain hysteresis loops of solder joints in the double-beam joint specimen. The agreement in results between FEM and experiments is very encouraging. This method is used to estimate the solder joint reliability of an small outline no-lead (SON) CSP assembly. The proposed model is validated by experimental testing data.