Impact of Viscoelastic Properties on Package Warpage Prediction

Warpage is a critical issue concerning electronic plastic packages and is mainly related to the epoxy molding compound (EMC). The molding process requires a large change in temperature, creating thermal gradients and mismatches which can lead to thermal stresses generating package deformation. Problems in controlling warpage will result in assembly yield loss and later in reliability issues, such as delamination and solder joint failures.Therefore, a solution to improve the reliability of packages is the prediction of warpage by employing finite element analysis (FEA). However, the standard FEA treats only linear elastic material properties lacking on the consideration of EMC viscoelasticity. With the aid of moldflow simulation tool, this work gives a comprehensive assessment to anticipate package warpage behavior with a validated model which considers the viscous and elastic properties of EMC by applying the Generalized Maxwell Model. The study is supported by experimental analysis as well as numerical modelling.