Improved Analytical and Semi-Analytical Durability Models (Constrained Models) for Various Surface-Mount Configurations

Several analytical and semi-analytical models to predict solder joint durability under thermal cycling loadings have been proposed. In general, these models are overtly conservative often requiring extensive experimental and/or finite element calibration. We present, based on the physics of the deformation process, a direct approach to improve these classes of model by resolving one of the major causes of conservatism. Our contribution is applicable to virtually all known surface mount configurations. The improved models (henceforth termed as constraint models) retain the simplicity of use of the existing ones. The efficacy of constraint approach is demonstrated on leadless resistors and comparisons are made with existing models and experimental data.