US Patent 7846218 Method of manufacturing electrolytic capacitor

As to each of a capacitor element employing an anode foil having a matrix made of a metal and a film, provided on the surface of the matrix, made of an oxide of a metal different from the metal of the matrix and a capacitor element employing an anode foil having a matrix made of a prescribed metal and a film of an oxide of the metal and a cathode foil having a matrix made of another metal different from the metal, formation treatment is performed on an end face of the anode foil exposing the surface of the metal forming the matrix by applying a positive voltage to an anode lead wire and applying a negative voltage to a cathode lead wire. Thus, an electrolytic capacitor resistant against corrosion or the like is obtained.