No abstract

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 be estimated because of the complex interaction between creep and fatigue of solder materials. Conventional life prediction method such as Coffin-Manson relation or its modifications may give erroneous results at low strain range. In this paper, a nonlinear finite element based model is introduced for predicting the thermal fatigue life of solder joints. This method not only considers the damage evolution in the solder, but also saves substantial computational efforts. In the present model, the evolution of damage is determined by the collapse of hysteresis loops of shear stress-strain of solder joints in the double-beam joint specimen. The agreement in results between FEM and the experiment is very encouraging. This method is used to estimate the solder joint reliability of an SON CSP assembly. The proposed model is validated by experimental testing data.