Abstract: A formed substrate, wherein the surface of the valve-acting metal having a dielectric film is at least partially covered with an oxide comprising Si, valve-acting metal element and oxygen, preferably, wherein the content of Si in the formed foil having an aluminum oxide dielectric film decreases continuously from the surface of the dielectric film toward the inner part in some regions in the aluminum dielectric film thickness; a method for producing the formed substrate; and a solid electrolytic capacitor comprising a solid electrolyte on the formed substrate. A solid electrolytic capacitor manufactured by using a formed substrate according to the present invention, improved in adhesion to an electrically conducting polymer (solid electrolyte) with its area coverage contacting the polymer being sufficiently large, is increased in the electrostatic capacitance among individual capacitors and improved in the LC yield as compared with capacitors otherwise manufactured.

Abstract: A formed substrate, wherein the surface of the valve-acting metal having a dielectric film is at least partially covered with an oxide comprising Si, valve-acting metal element and oxygen, preferably, wherein the content of Si in the formed foil having an aluminum oxide dielectric film decreases continuously from the surface of the dielectric film toward the inner part in some regions in the aluminum dielectric film thickness; a method for producing the formed substrate; and a solid electrolytic capacitor comprising a solid electrolyte on the formed substrate. A solid electrolytic capacitor manufactured by using a formed substrate according to the present invention, improved in adhesion to an electrically conducting polymer (solid electrolyte) with its area coverage contacting the polymer being sufficiently large, is increased in the electrostatic capacitance among individual capacitors and improved in the LC yield as compared with capacitors otherwise manufactured.