Modeling of Molded Electronic Package Warpage Characteristic with Cure Induced Shrinkage and Viscoelasticity Properties

One of the challenges for developing an electronic package is to understand the dynamic warpage behavior of the package even before having the real physical sample. Hence, industry relies on the use of simulation tools, be it the finite element model and analytical equations, to refine the design options to obtain a high confidence warpage prediction. However, this is never consistently predictable because of the underlying assumptions where the actual assembly process is a lot more complex. In this paper, the comparison of assembly process steps and modeling method is discussed coupled with a demonstration of the use of Moldex3D to predict the mold flow pattern and warpage prediction by leveraging the mold cure kinetics, PVTC (Pressure Volume Temperature Cure) and viscoelasticity material properties of the mold. Effect of mesh detail, mold shrinkage percentage and glass transition temperature were considered to provide some general trend of these parameters impacting the package warpage prediction. The use of analytical equation in managing the material properties transition from uncured to cured mold was demonstrated. Even with existing modeling capabilities, there is no one common modeling method and capability to capture all the potential package assembly process interaction. Hence, this is the motivation for further development.