Agitation for the electrodeposition of printed circuit boards
A detailed study of the characteristics of vibratory and air agitation including cathode reciprocation methods for electrodeposition processes and their application for plating of composites and printed circuit boards has been carried out. In tanks agitated by air bubbles, it was found that the enhancing effect of air bubbles on the mass transfer coefficient is a function of the gas voidage fraction, irrespective of the absolute values of the liquid flow velocity, the gas flow rate and the gas distributor employed. A sensor based on limiting current density characteristics of a wire tip electrode has been shown to be capable of measuring local variations of agitation and its effect on coating thickness variations during electrodeposition. The effectiveness of agitation is expressed as an enhancement factor.