In the previous papers, the author reported that leveling action was little affected by sorts of bath (K⁺ and Na⁺), concentrations of copper and free cyanide in the bath, temperature of bath, stirring, and addition of sulfur compounds, etc. depressing cathode polarization; but, the application of periodic reverse current and, in particular, its combination with stirring obtained more effective results.
In this paper, with the object of investigating the leveling mechanism of P.R. current, the effects of ratio of currents between normal and reverse, current density, reverse current density, and the above additives were determined.
The results were summarized as follows.
1) The leveling action on copper deposits was more improved with the increase in metallic copper concentration, decrease in free cyanide concentration, etc. which increased anode polarization. (However, these effects were very little in D.C.)
2) Leveling action was improved by stirring of bath, but there were little effects of bath temperature.
3) Leveling action was generally improved with the increase in time and density of reverse current.
4) Additived containing metals, which co-deposit with copper, depressed the leveling action, but the addition of compounds containing sulfur, which can easily be freed, improved the action. Addition of most of organic compounds had little effects on leveling. However, in any baths with additives, the action was improved by stirring.