Physics of Failure Based Simulation and Experimental Testing of Quad Flat No-Lead Package

In this work, finite element analysis and experimental testing were performed to analyze the delamination failure in quad flat no-lead (QFN). Interfacial delamination during post-mold cure process and precondition test is a critical reliability issue for plastic IC packages. The delamination failure weakens the internal structural strength of the package and affects product reliability. Available evidence indicates that, in the interface delamination, initially generated small voids gradually expand due to thermal stress or hygro-mechanical stress. Furthermore, due to the cracks on the interface, moisture easily penetrates into the package. In plastic IC packages, this can result in not only electrical failure, but also chemical reactions that would lead to corrosion. In the present study, delamination occurred on the interface between the Cu pad and the molding compound, as well as on the interface between the die and the molding compound and the Cu pad and molding during the precondition test. This research can help in improving product reliability by preventing the delamination failure in the QFN package by analyzing physics of failure (PoF).