Thermomechanical Modeling of Sintered Silver – A Fracture Mechanics-Based Approach

Sintered-silver has proven to be a promising candidate for use as a die-attach and substrate-attach material in automotive power electronics components. It holds promise of greater reliability than lead-based solders – especially for higher temperatures (> 200°C). Accurate predictive lifetime models of sintered silver need to be developed and its failure mechanisms thoroughly characterized before it can be deployed as a die-attach or substrate-attach material in wide-bandgap device-based packages. We present a finite-element-method (FEM) modeling methodology which can offer greater accuracy in predicting the failure of sintered silver under accelerated thermal cycling. A fracture-mechanics-based approach is adopted in the FEM model and J-integral/thermal cycle values are computed. In this paper, we outline the procedures for obtaining J-integral/cycle values in a computational model and report on the possible advantage of using these values as modeling parameters in a predictive lifetime model.