Failure analysis and precaution of plastic encapsulated microcircuits

The paper introduces the common failure mechanisms and their effect on the Plastic Encapsulated Microcircuits (PEMs). During the reflow soldering procedure, delamination between plastic mold compound/die or plastic mold compound/lead frame interface occurs frequently. Delamination is the channel for vapour to inbreak into the PEMs and affects its reliability. In this paper, the author analyses the failure mechanism of delamination and provides two typical failure analysis cases to explain it. The micro-processor failed because the pop-corn effect leads to delamination between its´ plastic mold compound/lead frame interface. The SRAM failed because the thermal-expansion coefficient mismatch of the plastic mold compound and the die. In the end, some precautions for reducing such failures are presented.