Catalytic anodes for electrodeposition: A study for acid copper printed circuit board (PCB) production

Purpose – Insoluble anodes have long been used as an alternative to the preferred soluble types, primarily for their practicality and without great attention to their efficacy. However, since about 1970 so-called catalytic anodes, typified by platinised titanium, have been increasingly used for electrochemical processes without too much attention to possible side-effects. The purpose of this paper is, therefore, to review the types of commercially available catalytic anodes and their electrochemical properties, particularly with respect to acid copper electroplating. Design/methodology/approach – Commercially available catalytic anodes were obtained from various anode suppliers and their electrochemical properties and behaviour with respect to acid copper electroplating were studied. Findings – While the oxidising capability of catalytic anodes is undisputed, it can lead to oxidation of organic species in electroplating solutions. This in turn can lead to loss of control and additional costs for additives in electrodeposition. This study has addressed the issue and the paper attempts to set down some data-based rules for the selection process. It also discusses some ways of optimising the choice of anode for acid copper processing of printed circuit-related processes. Originality/value – The paper determines the benefits and problems associated with the utilization of catalytic anodes in acid copper electroplating baths and, in particular, their effect on brightener consumption. It describes the factors affecting this phenomenon and describes a novel method for overcoming it.