Laser marking of raw aluminum anode foil to induce uniform patterning etching

Abstract

A method of producing a highly etched electrode for a capacitor from a foil is disclosed. The method comprises first applying a laser beam to the foil to form a plurality of marks on the foil surface and then etching the foil. Preferably, the laser marks facilitate etching of foil surface in areas near the marks and retard etching of foil surface inside the marks. After etching, the foil is further processed in a combination of optional steps such as forming and finishing steps. The laser marking of the foil allows for positional control of tunnel initiation, such that tunnel initiation density and the location of tunnel initiation is controlled. By controlling the position of tunnel initiation, foils are etched more uniformly and have optimum tunnel distributions, thus allows for the production of highly etched foils that maintain high strength and have high capacitance. The present invention further includes an electrolytic capacitor comprising etched aluminum anode foils, which have been prepared using the methods of the present invention.