Comparison of Mechanical Modeling to Warpage Estimation of RDL-First Fan-Out Panel-Level Packaging

Abstract

To meet the requirements of low cost, thin vehicles, and multiple functions, the fan-out panel-level packaging (FO-PLP) is introduced to be one of the next-generation packaging technologies. However, the warpage issue of FO-PLP remains a critical concern during temperature cycling manufacturing processes. The utilization of finite-element analysis (FEA) to estimate the warpage of FO-PLP and to address the major mechanism of warp-induced failure is therefore crucial. Given that an increase in the structural complexity of packaging follows the advancement in technological development, the effect of redistribution layer (RDL) on packaging warp considered in FEA becomes greatly difficult. The complicated RDL might cause computational bottlenecks. For this reason, several equivalent material approaches composed of composite theory and simulation-based material testing approach are proposed and compared with resolve the abovementioned problem. The gravity effect is considered in the present process-oriented FEA to acquire accurate warpage. To perform the foregoing FEA, identifying how to determine the equivalent reference temperature at each step of manufacturing process is the key. In this article, three methods, namely, zero deformation approach, force equilibrium approach, and modified Timoshenko bimaterial approach, are proposed. To validate these methods, a comparison of warpage between the experimental measurement and simulation is conducted. The analytic results demonstrate that the modified Timoshenko approach has the best ability to evaluate the warpage of RDL-first FO-PLP among them due to the feasible assumption for the actual mechanical behavior of warpage. With regard to the extraction of equivalent material, the results indicate that the simulation-based material testing approach is more suitable to obtain the equivalent RDL. The estimated warpage has only a 0.9% deviation between the simulation and experiment when the modified Timoshenko bimaterial approach combined with the simulation-based material testing approach is adopted. Consequently, the RDL-induced warpage in FO-PLP can be accurately estimated through the presented simulation methodology.