Pb-Free Solder Joint Thermo-Mechanical Modeling: State of the Art and Challenges

Abstract

Acceleration factors and predictive life models are of use to build-in board assembly reliability and estimate solder joint life at the design stage. They allow designers to answer management and end-users’ reliability questions. This paper reviews the grand families of solder joint reliability models that can help answer these types of questions. Different categories of models were reviewed, examples were provided and model limitations were discussed. Emphasis is on engineering models for Sn-Pb and Pb-free assemblies. Differences in the microstructure and failure mechanisms of near-eutectic Sn-Ag-Cu solders versus Sn-Pb are also reviewed, as they present new challenges to the development of thermo-mechanical models for surface mount assembly reliability assurance.