Warpage modeling for 3D packages

Package warpage is a primary concern in a package-on-package. To enhance the accuracy of modeling prediction, viscoelastic parameters, the change of material properties and cure shrinkage were studied with a dynamic modulus analysis (DMA) and a thermal mechanical analysis (TMA) for a mold compound. Material properties obtained from the TMA, DMA tools were introduced to finite-element-based models. The validation of models was verified with a shadow moiré for package warpage. As model simplification, inverse approach is described for an example of package warpage.