The Influence of a Surface Active Agent on the Electropolishing of Copper

Abstract

Previous work has shown that surface active agents can improve the finish obtained on copper electropolished in orthophosphoric acid solutions, and this beneficial action is examined in greater detail. The evidence indicates that the cationic surface active agent cetyl trimethyl ammonium bromide is adsorbed at both the anode surface and on the walls of oxygen bubbles. These factors are shown to account for the improvement in the micropolishing characteristics of the bath and in the reduction in the size of the pits formed on the anode during slow oxygen evolution.

Consumption of Cetyl Trimethyl Ammonium Bromide (CTAB) during Electrodeposition of Lead Dioxide

“…Since CTAB is a cationic surfactant, its consumption for cathodic reaction can very well be expected. However, the consumption of CTAB for the anodic reaction cannot normally be expected, but the results obtained are similar to the observations made by Lorking (10) in the experiments on anodic polishing of copper. The consumption of CTAB can be attributed to depletion arising out of adsorption and/or oxidation of the organic molecule itself.…”

“…It is now well established that the cationic surfactant is also consumed, perhaps by adsorption/oxidation at the anode during the deposition of lead dioxide, and these results are similar to the observations of Lorking (10). The lower consumption of CTAB in the electrolyte coupled with the obtaining of the desired deposit at higher temperature during the deposition of lead dioxide make the process interesting and attractive from a practical point of view.…”