Importance of molding compound chemical shrinkage in the stress and warpage analysis of PQFP's

This paper addresses the use of finite element (FE) techniques to predict residual warpage in plastic quad hat packs (PQFP's) after encapsulation, Experimental measurements of package warpage are used to validate FE models of the packages, Failure to incorporate mold compound chemical shrinkage into the FE analysis leads to erroneous predictions of package warpage. The warpage sensitivity of different packages to changes in downset is presented, The validated FE package models predict stress levels in packages which are 70% greater than those with temperature coefficient of expansion (TCE) shrinkage alone and questions the accuracy of previous simulations which do not include molding compound chemical shrinkage.