Experimental and Simulation-based Investigations on the Influence of Thermal Aging and Humidity on the Warpage of Molded Plastic Packages

In this study the impacts of temperature and moisture on the warpage of molded plastic packages were investigated. The investigation started with material characterizations. The influences of post-mold cure, reflow soldering, temperature cycles and high temperature storage on the material parameter (Young¿s modulus, coefficient of thermal expansion and glass transition temperature) of the investigated Epoxy Molding Compound (EMC) were investigated. By using test specimens (bi-material systems composed of EMC and copper, EMC and silicon) as well as real molded plastic packages (QFN packages), it was shown how material parameter changes due to thermal aging of EMC can lead to warpage changes of molded plastic packages. The impact of thermal aging on the structural changes of EMC was investigated. The oxidation layer, which developed on the surfaces of EMC due to thermal aging, was characterized. The formation of a second glass transition temperature in EMC due to thermal aging was investigated as a function of storage time and storage temperature. In the last chapter of this study, the simultaneous impact of temperature and moisture on the warpage of molded plastic packages was investigated by means of experiments and simulations. This study provides a deep understanding of warpage changes and stress changes respectively in molded plastic packages, when these are subjected to reflow soldering, temperature cycles, high temperature storage and moisture.