Investigation of moisture-induced failures of stacked-die package

The present work studies the moisture induced failures of a stacked-die package. The study includes various experimental tests to find the characteristics of constituent packaging materials such as interfacial strength, hygro-swelling property and vapor pressure, and a comprehensive finite element analysis integrating the effects of the hygro-swelling stress, the thermo-mechanical stress and the vapor pressure. Specifically, the vapor pressures with respect to the moisture concentration and the temperature in epoxy molding compound were characterized experimentally by combined TMA/TGA technique. In the numerical stress analysis, the interfacial delamination was newly simulated by applying a cohesive element modeling technique, in which a quadratic traction damage initiation law and an exponential displacement separation law were used.