Along with the recent remarkable development of the electronics industry, further miniaturization and higher performance of electronic devices are anticipated. Meeting these demands necessitates the miniaturization of built-in parts. One such component is a printed circuit board（PCB）. Miniaturizing the PCB, the base on which the electronic components are mounted, requires increased density. The semi-additive method, which enables fine wiring formation as a manufacturing method, is mainstream, as are plating and etching technologies responsible for miniaturization and enhanced reliability of PCB manufacturing and related component-mounting technologies.

For this study, we measured the AC impedance in the etching process. We assessed the correlation between surface roughness and AC impedance data obtained using atomic force microscopic measurements for monitoring roughness changes over time. Furthermore, copper corrosion processes and reduction processes of the etching solution during etching were clarified by the analysis of polarization curves.