Effect of viscous film on electrochemical polishing of copper microstructures

The surface quality of copper (Cu) microstructures restricts the improvement of their performance. In order to improve the surface quality of Cu microstructures, a subsequent polishing process is required for the microstructures. Electrochemical polishing (ECP) has great potential in high-quality surface polishing of metal structural parts. The viscous film is the key to the realization of the Cu ECP process. In this paper, a multiphysics coupled model is used to analyze the effect of the viscous film and its fluidity on the current density and material removal rate (MRR) at different positions of the microstructure. The simulation and experimental results show that the generation and flow of the viscous film during the ECP process leads to differences in the current density at different positions of the microstructure, thus causing differences in the MRR at different positions of the microstructure. The material removal of the microgroove with thicker viscous film was uneven and smaller. The ability of ECP to process the microgroove was improved by reducing the accumulation of viscous film in the microgroove. This study is not only instructive for the ECP process of microstructures, but also contributes to the further understanding of the ECP mechanism.