Effective Computational Models for Addressing Asymmetric Warping of Fan-Out Reconstituted Wafer Packaging

Abstract

Fan-out packaging has been treated as one of the most capable wafer-level packaging scheme but it usually accompanies with significant wafer warpage. In particular, asymmetric warping is frequently reported to cause numerous severe problems and should be properly resolved. Traditionally, full scale finite element simulations are usually used for addressing the needs and for providing possible engineering solutions. However, its case-by-case nature and enormous computational effort usually make it extremely inefficient for performing full scale simulation at the early design evaluation stage, where efficient semi-analytical or efficient numerical models should be used. In this work, full fan-out structures are firstly simplified into bi-layer equivalent structures and both the semi-analytical bifurcation temperature and post-bifurcation warpage predictions are then developed based on their original ideal analytical form for counting the needs in engineering applications. Through the comparison and correction using 3D finite element simulations, the developed models should be effective for providing trend and parameter- dependent predictions. Finally, essential preparations on building process emulator for chip-first or -last processes are presented to serve as the benchmarks for evaluating the performance of subsequent simplified process emulator in packaging warpage analyses.