Finite element analysis of flip - chip on board (FCOB) assembly during reflowsoldering process

摘要

Purpose - Out-of-plane displacement (warpage) is one of the major thermomechanical reliability concerns for board-level electronic packaging. The warpage and residual stresses can cause unreliability in the performance of electronic chip. An accurate estimation of the distortion and the residual stresses will help in selecting right combination of material for soldering and to determine the better assembly procedure of the chip. The purpose of this paper is to create a 3D nonlinear finite element model to predict the warpage, bending stresses, shear and peel stresses in a flip-chip on board (FCOB). Design/methodology/approach - A 3D finite element procedure has been developed considering the material nonlinearity during solidification for a FCOB assembly. Finite element results have been compared with the experimental values. Findings - The present finite element method gives better approximation of residual warpage and stresses compared to analytical models available in the literature. Originality/value - The 3D finite element approach considering the elasto-plastic and temperature-dependent material properties has not been attempted by any authors. Experiments have been conducted for the comparison of finite element values. The finite element results compare better than the methods available in the literature. Hence a better method for estimating the deformation and residual stresses in flip-chip assembly has been suggested.