Electrochemical-mechanical polishing of copper using moist particle electrolytes: electrochemical behavior and surface smoothing mechanistic

Copper is extensively employed in aerospace, surface engineering, and microelectronics due to its excellent electrical conductivity, thermal conductivity, and ductility. Due to the stringent service performance requirements in these high-end application fields, extremely high demands are placed on the surface quality of copper components, necessitating submicron-level surface precision. To meet the demand for high-quality surfaces of complex copper components, this work proposes a Moist Particle Electrolyte- Electrochemical Mechanical Polishing (MPE-ECMP) method for efficient precision finishing. Electrochemical impedance spectroscopy, Tafel polarization, cyclic voltammetry, and linear sweep voltammetry are employed to investigate three particle electrolytes modified with functional groups (PS–SO 3 H, PS–NHCH 2 PO(ONa) 2 , and PP–COOH), and the electrolyte with the highest removal rate is identified. Polishing tests are then conducted to evaluate surface roughness evolution, material removal, and the smoothing mechanism. Results show that PS–SO 3 H achieves stable copper dissolution without oxide formation and exhibits the highest removal rate. It reduces roughness from Sa=25.48 μm to Sa=0.25 μm with a removal rate of 1.66 mm 3 /h, 5.12 times higher than conventional liquid electrochemical polishing, owing to preferential peak removal. This study clarifies the electrochemical behavior and smoothing mechanism of MPE-ECMP and provides theoretical and experimental support for its application in polishing complex metallic components.