Simulation of Effect of Solder Balls Layout on Warpage and Interfacial Stresses of FBGA

Abstract

The finite element method is used to construct the sequential processing model of the package. The model is used to simulate the warpage and interfacial stresses of FBGA (Fine-pitch Ball Grid Array) package due to the coefficient of thermal expansion mismatch between layered materials of package during assembly processes. The processing model uses the function of element birth and death to simulate the processing step of package model, considering the sequentially accumulated warpage and stresses during the processing steps. The induced package stresses can cause the delamination between die/die attach interface. In order to verify the simulation results, the simulated package warpage of a standard package is compared with the measurement of package warpage of the package. In this study, the effect of solder balls layout on the warpage and interfacial stresses at die/die attach interface is discussed by simulation results.