Simulation of Leveling in Electrodeposition

A model of current distribution and electrode shape change for electrodeposition in the presence of diffusion-controlled leveling agents has been developed. The system is treated as a special case of secondary current distribution, with the surface overpotential taken to depend on both the current density and the transport-limited flux of the leveling agent, according to an empirical relation adapted from polarization data measured at different conditions of agitation. The spatial variation of the leveling-agent flux is determined from a concentration field problem based on the assumption of a stagnant diffusion layer. The solution is obtained by the boundary element method, with a flexible moving-boundary algorithm for simulating the advancement of the electrode profile. To illustrate the model's performance, the evolution of a groove profile during deposition of nickel from a Watts-type bath containing coumarin is predicted and compared with measurements reported in the literature. © 1990, The Electrochemical Society, Inc. All rights reserved.