A new approach to metal electrodeposition at a periodically changing rate - Part I. The reversing overpotential method

A method of increasing the apparent deposition exchange current density val ue in reversing overpotential (RO) copper electrodeposition is described. I n pulsating overpotential (PO) metal electrodeposition, the current density during the 'off' period is anodic, and proportional to the exchange curren t density value. The current during the 'off' period in PO copper electrode position can be increased by appropriate anodic polarization. This method i s referred to as the RO method to distinguish it from the pulsating method. In order to maintain the average current density in this case, it is neces sary to increase the cathodic current density during the 'on' period. Hence , the current density during the anodic period can be considered as proport ional to the exchange current density for some other deposition process, ch aracterized by a larger exchange current density value. The apparent deposi tion process exchange current density can be increased easily by using diff erent current densities during the anodic period, and different morphologie s for the same average current density can be expected. In this way, previo usly unknown morphologies of copper electrodeposits in the overpotential re gion used were obtained as spongy and needle-like forms. (C) 1999 Elsevier Science S.A. All rights reserved.