ChemInform Abstract: DISTRIBUTION OF LOCAL CURRENT DENSITIES DURING COPPER ELECTRODEPOSITION ON A PLANE VERTICAL CATHODE

Abstract

The distribution of local current densities on a plane vertical cathode was measured during copper electrodeposition with miniature probes imbedded in the host cathode plate. Preliminary tests were carried out, and appropriate experimental conditions were established. During the electrolysis of unstirred and solutions, local current densities are uniform in the vertical direction at low average current densities. With increase in average current density, they decrease in the upward direction from the lower edge of the cathode and are proportional to the power of the height at the limiting current. The theoretical and experimental distributions of the local current densities in solution were in good agreement with each other. From measurements with , and solutions, it was found that the distribution is virtually uniform in the vertical direction when the average cathodic current density is lower than one‐half the limiting value. This is due to the lower specific conductivity of the solutions of lower acid concentration. At the cathodic limiting current, variation in the local current densities in the vertical direction was smaller than the theoretical prediction. It was also observed that the local current densities in the upper portion of the cathode oscillate irregularly in the vicinity of the limiting current. It was supposed that the natural convective flow becomes turbulent in this region of the cathode due to the hydrodynamic resistance at the surface of the uneven electrodeposit.