The effect of insoluble anodes on the process control and deposit quality of acid copper electroplating baths

Despite the fact that insoluble anodes are becoming more utilized in acid copper electroplating for printed circuit board manufacture, little work has been published on the impact of using such anodes on the process control of the baths or their effect on the electroplated deposit. In this study, two electroplating tanks were set up, which were identical in all aspects except that one tank used the traditional phosphorized soluble anodes, whilst the other employed insoluble anodes. Incorporating insoluble anodes into the electroplating tank caused a large increase in brightener consumption rate and the mechanical properties of the electroplate and the throwing power tended to be somewhat inferior to when soluble copper anodes were employed. This was thought to be due to the problems of controlling the brightener concentration at optimum levels rather than to any deterioration in the electrolyte, attributable to, for example, by‐product build‐up.