Centrifugal Etching

A cell consisting of a rotatable double-walled cylinder is described for the study of etching under conditions of enhanced gravity. Rotation rates of 6000 revolutions per minute giving g values of up to 600 were possible with the set-up. The cell was tested by etching masked patterns in a copper plate with an aqueous FeCl3 solution. The dependence of the etch rate on the system parameters (g value, ferric ion concentration, solution viscosity) is shown to be in agreement with trends predicted by a boundary-layer model. The results show that "centrifugal etching" involving artificial gravity gives a markedly increased etch rate and a reduced undercutting of the mask edge. It is shown that, in principle, the cell can be scaled up to dimensions interesting for industrial applications