CONTROLLED ELECTROPLATING THROUGH GELATIN FILMS

A new process for generating three dimensional surface features and contours by electroplating is described. The current density is spatially modulated by electroplating directly through variable thickness polymeric films which are permeated with electrolyte. The thickness of the films is controlled by photochemical cross-linking through an optical mask consisting of a photographic negative. The negative may contain gray scale shaded areas as well as binary (transparent/opaque) regions. A more transparent area on the negative gives rise to a more cross-linked, thicker region of film, which in turn impedes ionic current flow leading to a thinner layer of electroplated metal. The process provides a generalized method of transcribing a two dimensional optical density map into a three dimensional surface contour. Spatial resolution in the micron range may be achieved.