Fabricating an electrode for capacitor includes performing a first set of one or more preliminary oxide formation operations on a sheet of material. The method also includes performing a capacitance test on the sheet of material so as to determine the capacitance of the sheet of material after the one or more preliminary oxide formation operations. The method proceeds on a first path in response to a first result of the capacitance test and on a second path in response to a second result of the capacitance test. The first path includes performing a second set of the one or more preliminary oxide formation operations on the sheet of material so as to reduce the capacitance of the sheet of material below the determined capacitance. The second path excludes performing any preliminary oxide formation operations on the sheet of material.

A solid electrolytic capacitor that includes: a capacitor element having a valve action metal base with a core portion, a first porous portion and a second porous portion, a first dielectric layer on the first porous portion, a first solid electrolyte layer on the first dielectric layer, a first conductor layer on the first solid electrolyte layer, a second dielectric layer on the second porous portion, and a second solid electrolyte layer on the second dielectric layer, the first dielectric layer and the first solid electrolyte layer constituting a first capacitance portion, and the second dielectric layer and the second solid electrolyte layer constituting a second capacitance portion; a cathode through electrode electrically connecting the first capacitance portion to a cathode external electrode; and a connection portion connecting the second capacitance portion to the first capacitance portion.

An electrolytic capacitor includes a capacitor element and a solution containing a solute. The capacitor element includes: an anode foil provided with a dielectric layer on the anode foil; a cathode foil disposed to face the anode foil; and a conductive polymer layer disposed between the anode foil and the cathode foil. The cathode foil is provided with a first layer disposed on the cathode foil, the first layer including at least one selected from the group consisting of carbon, nickel, a nickel compound, titanium, and a titanium compound. The conductive polymer layer includes a conductive polymer in contact with at least a part of a surface of the first layer. The cathode foil has a roughened surface, and the roughened surface of the cathode foil has a surface expansion rate ranging from 1.5 cm.sup.2/cm.sup.2 to 500 cm.sup.2/cm.sup.2, inclusive.

An electrolytic capacitor includes a capacitor element and a solution containing a solute. The capacitor element includes: an anode foil provided with a dielectric layer on the anode foil; a cathode foil disposed to face the anode foil; and a conductive polymer layer disposed between the anode foil and the cathode foil. The cathode foil is provided with a first layer disposed on the cathode foil, the first layer including at least one selected from the group consisting of carbon, nickel, a nickel compound, titanium, and a titanium compound. The conductive polymer layer includes a conductive polymer in contact with at least a part of a surface of the first layer. The cathode foil has a roughened surface, and the roughened surface of the cathode foil has a surface expansion rate ranging from 1.5 cm.sup.2/cm.sup.2 to 500 cm.sup.2/cm.sup.2, inclusive.

A capacitor disposed inside a multilayer substrate that includes a conductive pattern on a surface thereof and an anode portion having a first conductive metal member and a porous portion disposed on a surface of the first conductive metal member, a cathode portion, and a dielectric layer disposed between the anode portion and the cathode portion. Moreover, the anode portion is led out to a surface side of the multilayer substrate by a connection electrode including an alloy layer containing a metal forming the first conductive metal member and a conductive layer disposed on the alloy layer, and in which the connection electrode is connected to the conductive pattern formed on the surface of the multilayer substrate.

An electrode foil for an electrolytic capacitor includes a base material containing a valve metal and a dissimilar metal composite layer covering a surface of the base material. The dissimilar metal composite layer includes a mixed region in which a first metal and a second metal are mixed. The second metal is different from the first metal. The mixed region constitutes at least 50% of the dissimilar metal composite layer in a thickness-wise direction of the dissimilar metal composite layer. Each of a content M1 of the first metal and a content M2 of the second metal with respect to all metals in the mixed region is 1 atomic % or more.

The electrolytic capacitor has a conductive sheet with a central portion defined by a peripheral edge, a first tail extending out from the peripheral edge in a first direction, and a second tail extending out from the peripheral edge in a second direction. The second direction is opposite the first direction. The first tail and the second tail each have a free end with a first recess at the free.

The electrolytic capacitor has a conductive sheet with a central portion defined by a peripheral edge, a first tail extending out from the peripheral edge in a first direction, and a second tail extending out from the peripheral edge in a second direction. The second direction is opposite the first direction. The first tail and the second tail each have a free end with a first recess at the free.

A solid electrolytic capacitor element includes an anode foil that includes a porous part in a surface layer of the anode foil, a dielectric layer,and a cathode part. The cathode part includes a solid electrolyte layer that covers the at least a part of the dielectric layer and a cathode lead-out layer that covers at least a part of the solid electrolyte layer. The anode foil includes a first part that is a cathode forming part where the solid electrolyte layer is formed and a second part where the solid electrolyte layer is not formed. And the anode foil includes a dense part in the surface layer in at least one of the first part and the second part. The dense part has a porosity smaller than a porosity of the porous part. The second part includes at least an anode part including an end part of the anode foil opposite to the first part.

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.