FEM simulations for built-in reliability of innovative Liquid Crystal Polymer-based QFN packaging and Sn96.5Ag3Cu0.5 solder joint

In this study, Quad Flat No-lead (QFN) cavity package based on LCP and the reliability impact of the package geometry are investigated. A well-established model of Sn96.5Ag3Cu0.5 solder joint fatigue based on the Darveaux's methodology leading to strain energy density estimation is used. A dedicated Design of Experiments (DoE) is performed to assess the optimal thermo-mechanical properties of the LCP package leading to the maximum operating lifetime. A correlation between predicted lifetime results and optimal thermo-mechanical properties of the package is obtained depending on the geometry of the QFN under study.