The first step of the process is the coating of the samples with a thin (10µm) polymeric coating. A uniform thickness deposition can be obtained on complex shape objects by electrophoresis. This protective layer is then locally exposed to a focused laser beam. A machine vision imaging setup and motorized stages allow for the precise positioning of the laser irradiation sites. Clean and very reproducible ablation of the film is obtained using a short pulse UV laser. The result of this lithographic process is a precisely microstructured protective coating, with well-defined openings to the underlying metal surface.
The samples are then immersed into an electrolyte. A power supply is connected to provide an electric tension between the processed piece and an inert counter electrode. When optimized voltage profiles and hydrodynamic conditions are applied, the unprotected areas of the workpiece are neatly attacked and a smooth and shiny engraving is achieved. Precise dimensioning of the engraved patterns is obtained by monitoring the electric charge flown through the system. This control is very precise and, unlike for chemical etching, is independent of the aging and temperature of the bath.
After accomplishment of the electrochemical dissolution, the polymeric coating is removed with a stripper.