An electrode holder and a method for producing an electrode for an aluminum electrolytic capacitor are provided that enable prevention of exfoliation of a porous layer during chemical formation even when the porous layer is formed on an aluminum electrode so as to have a thickness of 200 micrometers or greater. When an aluminum electrode 10 having at least one surface 11 on which a porous layer 17 having a thickness of 200 micrometers or greater is formed is subjected to chemical formation in a chemical formation solution, the aluminum electrode 10 is held by an electrode holder 50. The electrode holder 50 includes: an insulating first support plate 51 configured to overlap the one surface 11 of the aluminum electrode 10; an insulating second support plate 52 configured to overlap the other surface 12 of the aluminum electrode 10; and a connecting part 53 configured to connect the first support plate 51 and the second support plate 52 to each other. A portion of the first support plate 51 that overlaps the porous layer 17 while being in contact therewith is formed with a porous member 510.

An electrode foil for an electrolytic capacitor including a metal porous portion, and a metal core portion continuous to the metal porous portion. When the metal porous portion is equally divided in three in a thickness direction of the metal porous portion into a first region, a second region, and a third region sequentially from the metal core portion side, the first region has a porosity P1, the second region has a porosity P2, and the third region has a porosity P3, satisfying P1<P2<P3.

An electrode foil for an electrolytic capacitor including a metal porous portion, and a metal core portion continuous to the metal porous portion. When the metal porous portion is equally divided in three in a thickness direction of the metal porous portion into a first region, a second region, and a third region sequentially from the metal core portion side, the first region has a porosity P1, the second region has a porosity P2, and the third region has a porosity P3, satisfying P1<P2<P3.

An electrode foil having high capacitance per unit volume is provided. The electrode foil is an electrode foil for an electrolytic capacitor. The electrode foil is an electrode foil extending in a longitudinal direction and having a width direction orthogonal to the longitudinal direction, the electrode foil including an enlarged surface portion on a surface of the electrode foil, wherein a crack is formed in the enlarged surface portion in a direction oblique to the width direction.

To provide a thin film capacitor having high adhesion performance with respect to a multilayer substrate. A thin film capacitor includes: a metal foil having a roughened upper surface; a dielectric film covering the upper surface of the metal foil and having an opening through which the metal foil is partly exposed; a first electrode layer contacting the metal foil through the opening; and a second electrode layer contacting the dielectric film without contacting the metal foil. A height of the first electrode layer is lower than a height of the second electrode layer. This enhances adhesion performance when the thin film capacitor is embedded in a multilayer substrate and improves ESR characteristics.

Method for forming a metallic component surface to achieve lower electrical contact resistance. The method comprises modifying a surface chemical composition and creating a micro-textured surface structure of the metallic component that includes small peaks and/or pits. The small peaks and pits have a round or irregular cross-sectional shape with a diameter between 10 nm and 10 microns, a height/depth between 10 nm and 10 microns, and a distribution density between 0.4 million/cm.sup.2 and 5 billion cm.sup.2.

Method for forming a metallic component surface to achieve lower electrical contact resistance. The method comprises modifying a surface chemical composition and creating a micro-textured surface structure of the metallic component that includes small peaks and/or pits. The small peaks and pits have a round or irregular cross-sectional shape with a diameter between 10 nm and 10 microns, a height/depth between 10 nm and 10 microns, and a distribution density between 0.4 million/cm.sup.2 and 5 billion cm.sup.2.

An electrode for an aluminum electrolytic capacitor and a method for producing the same are provided that enable improvement of water resistance of a chemical formation film having a withstand voltage of 400 V or higher. The electrode for an aluminum electrolytic capacitor is produced by performing a hydration step of bringing the aluminum electrode into contact with a hydration treatment liquid having a temperature of 78° C. to 92° C. to form a hydrated film on the aluminum electrode and a chemical formation step of performing chemical formation at a chemical formation voltage of 400 V or higher in a chemical formation solution having a temperature of 58° C. to 78° C. to form the chemical formation film on the aluminum electrode. In this method, the amount of the hydrated film is made appropriate. In this electrode for an aluminum electrolytic capacitor, the number of voids that are exposed on a cut surface when the chemical formation film is cut is 150 voids/μm.sup.2 or smaller, and thus the water resistance thereof is high.

An electrode for an aluminum electrolytic capacitor and a method for producing the same are provided that enable improvement of water resistance of a chemical formation film having a withstand voltage of 400 V or higher. The electrode for an aluminum electrolytic capacitor is produced by performing a hydration step of bringing the aluminum electrode into contact with a hydration treatment liquid having a temperature of 78° C. to 92° C. to form a hydrated film on the aluminum electrode and a chemical formation step of performing chemical formation at a chemical formation voltage of 400 V or higher in a chemical formation solution having a temperature of 58° C. to 78° C. to form the chemical formation film on the aluminum electrode. In this method, the amount of the hydrated film is made appropriate. In this electrode for an aluminum electrolytic capacitor, the number of voids that are exposed on a cut surface when the chemical formation film is cut is 150 voids/μm.sup.2 or smaller, and thus the water resistance thereof is high.

A capacitor and methods of processing an anode metal foil are presented. The capacitor includes a housing, one or more anodes disposed within the housing, one or more cathodes disposed within the housing, one or more separators disposed between an adjacent anode and cathode, and an electrolyte disposed around the one or more anodes, one or more cathodes, and one or more separators within the housing. The one or more anodes each include a metal foil that includes a first plurality of tunnels through a thickness of the metal foil in a first ordered arrangement, the first ordered arrangement being a close packed hexagonal array arrangement, and having a first diameter, and a second plurality of tunnels through the thickness of the metal foil having a second ordered arrangement and a second diameter greater than the first diameter.