Experimental and numerical investigation on warpage of QFN packages induced during the array molding process

An investigation on the process-induced warpage during the array-molding process of QFN packages was conducted both experimentally and numerically. A series of molding experiments for QFN matrix strips with the model-molding compounds were performed. In the molding experiments, different processing parameters, filler loading and die thickness were used. The warpage was measured by a contact probe coordinate measuring system. A cure-dependent constitutive model for the encapsulating EMC was applied to describe the behavior of the material during the curing process. The cure-dependent material parameters were incorporated into a finite element code MARC and numerical simulations were carried out for the QFN array-molding process. The effects of filler percentage of the molding compound, the curing temperature profiles and the die thickness on the warpage were studied. The results show that both of the filler percentage and the die thickness has a significant effect on the final warpage level.