A Study of the Composite Electrodeposition of Copper with Alumina Powder

Codeposition of a-alumina powder in an acidic copper plating solution was studied. We found the zeta potential of ~-alumina powder to be negative, which is probably the r ason why it shows much inferior codeposition as compared with a-alumina. The agitation of solution also affects the extent of codeposition strongly. The flow of electrolyte is necessary to maintain the particles in suspension. However, with too much agitation, the solution can blow away adsorbed alumina particles. The technology of codeposition of copper with alumina powder was first published by Sauter (1). He later found that only a-alumina powder is effective for codeposition (2). He also found that chloride ion significantly inhibited the codeposition process in an acidic copper bath. For this system, Tomaszewski (3, 4) found several reaction pro-moters e.g., thallium ion and cesium ion. As for the kinetics and mechanism, Snaith (5) first pro-posed the existence of mechanical bonding between meta