Interaction between PCB-Cu corrosion and electrochemical migration under the Coupling of electric field and thin liquid film

Abstract

An in-situ monitoring and observation experimental setup was designed in the coupled environment of a thin liquid film and an electric field. The interactive development of PCB-Cu corrosion and electromigration under different bias voltages, salt concentrations, and liquid-film thicknesses was investigated, and an interactive model was proposed. The results showed that electromigration of copper was dominant at a high voltage of 3 V, whereas corrosion occurred without salt deposition at a low voltage of 1 V. The growth rate of the dendrites decreased with increasing liquid film thickness. In the presence of 1 g/m2 of NaCl, dendrite growth was absent because corrosion precipitation occurred before dendrite formation, thereby hindering the migration of copper ions. At a higher NaCl deposition density of 10 g/m2, the electromigration of copper became dominant, resulting in the formation of many short dendrites, evenly distributed on the cathode at a low voltage of 1 V. These observations are consistent with the results of the in-situ current monitoring tests.