Review of Models and the Disturbed State Concept for Thermomechanical Analysis in Electronic Packaging

A number of models for thermomechanical stress analysis and fatigue failure of materials are reviewed and their capabilities and limitations are identified. The unified disturbed state concept (DSC) for constitutive modeling of materials and interfaces is presented and compared with other approaches. An approximate procedure based on the DSC is proposed for accelerated design-analysis and cyclic fatigue failure. Solutions of example problems using the DSC and associated computer (FE) procedures are included to illustrate its integrated and improved capabilities for analysis of stresses, strains, microcracking, fracture and fatigue failure, and reliability.