IMPORTANCE OF MOLDING COMPOUND CHEMICAL SHRINKAGE IN THE STRESS AND WARPAGE ANALYSIS OF PQFPS

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