FE Simulation Model for Warpage Evaluation of Glass Interposer Substrate Packages

Glass interposer substrates have attracted growing interest as an alternative to traditional organic and silicon-based interposers for 3-D integrated circuit (IC) and 2.5-D through silicon via (TSV) packages in recent years. However, while glass substrates have the advantages of excellent electrical isolation, superior RF performance, good coefficient of thermal expansion (CTE) adjustability, and the potential for large-scale fabrication, they are inherently brittle. Consequently, an appropriate choice of glass and epoxy molding compound (EMC) material is essential for minimizing the warpage of the molded wafer. To facilitate the package design process, this study, therefore, develops an ANSYS simulation model to predict the warpage of the molded glass wafer given the use of different glass and EMC materials. The validity of the simulation model is confirmed by comparing the numerical results for the warpage of an 8-in molded glass wafer with the experimental measurements obtained using an Advanced Metrology Analysis (aMA) system. Single-factor-analysis experiments are then conducted to examine the effects of five different control factors, namely, the glass substrate thickness, the glass CTE, the glass modulus, the EMC CTE, and the EMC modulus, on the warpage performance of the molded glass wafer. The simulation results provide useful guidelines for the design of robust glass substrate packages.