A Unified Model Approach for Solder Joint Life Prediction

In real world applications, the inherent resilience associated with as manufactured solder joints does not lead the solder joints to exhibit spontaneous degradation behavior as explained in various studies using Coffin-Manson and other models [1] [2]. On the contrary, solder joints spend substantial period of lifetime free of degradation or in which the rate of degradation is negligible and insignificant [3]. Therefore, any efforts that do not capture the initial degradation free life time result in underestimation of overall useful product life. This study presents an integrated approach that combines the crack initiation and crack propagation phases to provide a unified model for solder joint life prediction. Underlying thermo-mechanical physics of failure mechanisms responsible for degradation are used to develop the constitutive models separately for initiation and propagation phases. These models are then combined to come up with a unified life prediction model for solder joints. Owing to complex nature of degradation in initiation and propagation phases, non-linear regression methods have been utilized to estimate the model parameters. The resulting models are used to predict the total estimated life time of solder joints using crack initiation and crack propagation models on the dataset from a given study [3].