Role of mold in electrochemical migration of copper-clad laminate and electroless nickel/immersion gold printed circuit boards

The role of the mold in electrochemical migration (ECM) of printed circuit board (PCB) under DC bias was investigated using environment scanning electron microscope, 3D stereology microscopy, and scanning Kelvin probe. The mold under electrical bias can grow well and complete with the processes of growth, metabolism and proliferation. The mold can also promote metal ionization and localized corrosion and provide the ion source for ECM process. The cooperation of mold and DC bias promote ECM process on PCB and aggravate short circuit failure behavior. The proposed ECM mechanisms explain the ECM process of PCB under mold and DC bias environment.