Numerical modeling and experimental investigation in through-hole electrodeposition

The formulations of the traditional bulk-diffusion model and a refined, field model are presented in Chapter 1. In the bulk-diffusion model, the electrolyte is separated into two regions. They are the thin-diffusion layer region where mass transport occurs and the bulk region where no concentration gradient is assumed to exist. The field model considers the effect of ionic migration as well as mass transport in the whole electrolyte. The current distribution profiles from both models are compared in a typical industrial plating solution.; Chapter 2 provides a description of the experimental apparatus used to validate the field model for various levels of a supporting electrolyte. The average discrepancy in current distribution between the field model and the experimental results is less than 1 percent.; Chapter 3 deals with an investigation on the validity of the bulk-diffusion model in small through-holes. A numerical study is performed on the placement of the boundary layer and its effect on the current distribution. It is shown that when the Peclet number is greater than 100, the bulk-diffusion model is generally valid.; Chapter 4 discusses the fluid mechanics of a through-hole. The problem was solved by using the method of streamlines and vorticities. Streamlines, vorticity contours, axial velocity profiles, and radial velocity profiles are shown at different Reynolds numbers and geometry of the through-hole.; Chapter 5 presents the current distribution under mass-transfer controlled conditions on the new through-hole model. Very fine meshes must be placed on the front and back faces of the through-hole to compute accurately the flux in these regions. Results show that the major fraction of the current goes onto the front face and inside the through-hole while a minor amount occurs on the back face.; Chapter 6 presents the current distribution and surface concentration in the new through-hole model for cases below the limiting current. At low overpotentials, secondary-like current distributions occur with the major fraction of the current nearly evenly distributed to the front and back faces while a minor portion flows to the inside of the through-hole. The electric field is highest on the front and back faces since because of their proximity to the counter electrodes. At high applied potentials, the back face eventually becomes limited by mass transport.; Chapter 7 presents an experimental investigation on the current distribution in all regions of the through-hole in the presence of various levels of a supporting electrolyte. (Abstract shortened by UMI.)...