Modeling of the Metal Microstructure Formation by Local Electrodeposition onto Conducting Substrates

The formation of metal microstructures on metal substrates is theoretically analyzed by the example of local silver electrodeposition, using the numerical simulation of interrelated electrochemical and homogeneous chemical reactions. The silver electrodeposition localization and rate are shown to depend on the interrelation between full concentrations of ammonia, silver, and protons in solution. The ammonia relative concentration range is determined, which provided an acceptable combination of the silver electrodeposition localization and rate. By using some simplifications, the distributions of the concentrations of the participants in the reactions and the current density of silver ion reduction are numerically calculated for various concentrations of solution components and interelectrode distances. The degree of localization of metal deposition is shown to depend on the distribution of the concentrations of electroactive silver cations and the non-electroactive complex of this metal near the anode. The deposition rate was found to depend nonmonotonously on the interelectrode distances, which can be explained by difficulties in the reactants’ delivery at small interelectrode distances and increase of the fraction of the silver electroactive ions diffusing toward solution bulk at large interelectrode distances.