Patent ID: 7198733
Filing Date: 2007-04-03
Classification: H01G,Y10T

Abstract:
1. A formed substrate, which is a valve-acting metal substrate having a dielectric film, 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 O, wherein the content of Si present in the foil decreases continuously from the surface of the dielectric film toward the inner part in some regions in thickness of the dielectric film, the content ratio of Si measured by TEM-EDX and defined by the following formula: is 4% or more at the surface and decreases continuously toward the inner part at a rate of 0.5%/nm or more in some regions in thickness of the aluminum oxide dielectric film, and the valve-acting metal substrate is selected from the group consisting of aluminum, tantalum, titanium, niobium and alloys thereof.