Abstract
A control to reduce the warpage of LSI package is a critical issue to ensure good singulation, solder joint and its mechanical reliability in surface mount packaging. In this study, predicting methods of the ball grid array (BGA) warpage were investigated using a viscoelastic technology with introducing chemical shrinkage of mold compound. As a result, the package warpage was found to be well predictable in cooling process from molding temperature and heating process of reflow temperature under a precise warpage calculation corresponded to chemical shrinkage of mold compound. Thus, the warpage mechanism became clear through the parameter analysis of material properties. In order to obtain a minimum warpage for a material designing of mold compound, the following suggestion is supported; 1) To increase Tg, 2) To reduce modulus at high temperature.
