Combined pulsing currents and agitation for electrodeposition

Abstract

In order to exploit the full potential of current pulsing one may need to combine it with synchronised and pulsing solution agitation. The problem with providing pulsing agitation is that changes in the momentum boundary layer have a much larger time constant than that required for changing reaction conditions at the electrode surface. One agitation scheme which may not have this limitation is ultrasonication. Ultrasonic (US) transducers respond to pulsing electrical signals which can be switched within a second. In industrial tank systems the transducers are loaded on the wall of a tank, which allows the agitation to be transferred into the electrolyte immediately. In the current work, the effect of continuous vs pulse US agitation on metal deposition under mass transfer limitations has been examined. In order to test the applicability of this concept, copper has been deposited at a cathode which is separated from the anode by a gap of 0·3 mm using direct current and pulsing current deposition under silent and ultrasonic agitation conditions. The cell potential has been monitored to determine the stability of the process. Deposit roughness was determined as a test of process performance. To the authors’ knowledge, this work provides the first assessment of combining these two different pulsing parameters for electrodeposition.

Keywords:

• Pulse deposition
• Ultrasonic agitation
• Copper
• Combined current and agitation pulsing
• EnFACE

Acknowledgements

Simon Coleman acknowledges the studentship support by EPSRC grant EP/J500288/1. This work was supported by EU ‘MESMOPROC’ Grant 303550 and Royenface Ltd. This paper is based on a presentation given at the 6th European Pulse Plating Seminar, Baden, Austria, 7th March 2014.