Transfer molding process has been used in the packaging industry for decades for the encapsulation of all kinds of plastic packages. In the transfer-molding process, the solid but reactive epoxy molding compounds (EMCs) in the preformed pellet form are injected into the preheated mold that contains the substrate and the attached chip. The EMCs are thermally cured and then ejected with encapsulated parts. For microelectronics encapsulation, EMC selection and molding conditions can strongly affect the final quality of the encapsulated parts, such as warpage, wire sweep, microvoid formation and reliabilities. In this study, the curing behavior of two epoxy molding compounds from different sources was evaluated. The activation energies for curing reactions were estimated using Kissinger and Ozawa methods. These two EMCs were also subjected to process study through transfer molding. The warpage values of the encapsulated substrates with a dummy die were measured and the molded parts were inspected using an acoustic microscope. The processing conditions of these two EMCs were optimized. The determining factors for warpage control and void formation were evaluated through the design of experiments. (C) 2004 Elsevier B.V. All rights reserved.