JP2008258355A - Electrode foil for capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode foil for capacitors having capacity expanded by expanding a surface area further and having excellent mechanical strength for the electrode foil used for the capacitor for various kinds of electronic equipment. <P>SOLUTION: The electrode foil comprises a base material 1 made of valve action metal foil, and a vapor-deposited layer 1a of a valve action metal formed by deposition on the surface of the base material 1. The vapor-deposited layer 1a of the valve action metal is in a frost columnar structure toward the surface layer from the base material 1, and respective particles in each column are branched into a plurality of parts for integration, thus realizing a so-called Caulerpa lentillifera shape. Further roughening enlarges the surface area and increases mechanical strength and capacity. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a capacitor electrode foil used in various electronic devices.

  Capacitor electrode foils (hereinafter referred to as electrode foils) used for various capacitors are generally used with a roughened surface for the purpose of enlarging the capacity by increasing the surface area per unit area. The roughening operation is roughly classified into etching and vapor deposition.

  As for the above-mentioned etching, when the aluminum foil is electrolytically etched in an etching solution containing chlorine ions, the aluminum foil is subjected to DC electrolytic etching in the former stage, and the aluminum foil is immersed in the latter stage, and then AC electrolytic etching is performed. By gradually increasing the current density and then etching at a constant current density, even if the characteristics of the aluminum foil change, it is possible to create a constant initial pit that is the starting point for the subsequent AC electrolytic etching. In addition, there is disclosed a technique capable of manufacturing an electrode foil having a stable and stable quality (Patent Document 1).

In addition, by evaporation, aluminum is evaporated in an atmosphere containing oxygen or an oxygenated compound, and then condensed and solidified, so that the pressure in the deposit zone is fixed or movable in the chamber of 2.8 to 0.3 Pa. A technique is disclosed in which a relatively large capacity can be obtained by a method of forming a deposit at a thickness increase rate of 0.03 to 0.2 micrometers / second on one or both sides of a substrate (Patent Document 2). .
JP-A-9-171945 Japanese Patent Publication No. 7-15864

  However, in the conventional capacitor electrode foil, in the technique of Patent Document 1 in which the surface of the aluminum foil is roughened by etching, the surface area is further increased by etching from the viewpoint of the etching technique and the mechanical strength of the capacitor electrode foil. However, there is a limit, and it is extremely difficult to expand the capacity beyond this.

  In addition, in the technique of Patent Document 2 in which aluminum is vapor-deposited on the surface of an aluminum foil to roughen the surface, the necking portion is destroyed during formation because the connection (bond strength) between the particles forming the vapor deposition layer is weak. There is a problem, and when such a breakdown occurs, a current does not flow from the point where the breakdown occurs, so that a desired capacity cannot be obtained.

  Furthermore, in such a capacitor electrode foil in which it is difficult to ensure the bonding strength between the particles, the vapor deposition layer is destroyed by the mechanical stress applied when the wound element is manufactured. There is a problem that it is extremely difficult to manufacture a circular element.

  The present invention solves such a conventional problem, and provides an electrode foil for a capacitor that can increase the surface area by further roughening, have high mechanical strength, and realize high capacity. It is for the purpose.

  In order to solve the above-mentioned problem, the present invention comprises a base material made of a valve action metal foil and a valve action metal vapor deposition layer formed on the surface of the base material by vapor deposition, A frost columnar structure is formed from the base material to the surface layer, and each column has a structure formed in a so-called sea grape shape in which individual particles are branched into a plurality and integrally joined.

  As described above, the electrode foil for a capacitor according to the present invention is a so-called frost columnar structure in which a vapor deposition layer is formed from a base material to a surface layer, and each column is a single unit in which individual particles are branched into a plurality of pieces. By being formed in the shape of sea grapes, the surface area is increased by further roughening, and since it has high mechanical strength, it is possible to achieve the effect of achieving high capacity.

(Embodiment)
Hereinafter, the invention described in the entire claims of the present invention will be described by using embodiments.

  FIG. 1 is a SEM (scanning electron microscope) photograph (10,000 times) showing the structure of a capacitor electrode foil according to an embodiment of the present invention, and FIG. 2 is an enlarged SEM photograph (30,000 times) of the main part of FIG. ).

  1 and 2, reference numeral 1 denotes a base material made of an aluminum foil, 1a denotes an aluminum vapor deposition layer formed on the surface of the base material 1 by vapor deposition, and as can be seen from FIG. 1, the vapor deposition layer 1a is a base material. As shown in FIG. 2, a plurality of frost column structures are formed densely from 1 to the surface layer, and each column constituting the vapor deposition layer 1 a formed in such a frost column structure can be seen from FIG. 2. These are formed in a so-called sea grape-like structure in which individual particles are integrally bonded in a state of being branched into a plurality of branches.

  The capacitor electrode foil according to the present embodiment configured as described above uses a high-purity aluminum foil having a thickness of 50 μm. Argon gas and oxygen are allowed to flow into the vacuum atmosphere so that the aluminum foil is placed on the surface of the aluminum foil. These were prepared by vapor-depositing fine particles, both of which were performed using a known manufacturing apparatus and manufacturing method.

  The capacitor electrode foil according to this embodiment configured as described above has an extremely fine pore diameter mode of about 0.03 μm, as is apparent from the characteristic diagram showing the pore diameter distribution in FIG. Therefore, compared with about 0.15 μm, which is the mode value of the hole diameter of the same electrode foil by etching shown for comparison, it is extremely miniaturized, which can greatly increase the surface area. In addition to being able to do so, the vapor deposition layer 1a is formed in a frost columnar structure from the base material 1 to the surface layer, so that when viewed as a capacitor, it is excellent in impregnation of liquid (driving electrolyte, polymer, etc.). It is what has.

  Furthermore, since each column of the frost columnar structure is formed in a so-called sea grape shape in which individual particles are branched into a plurality of pieces and bonded together, the bond strength between the individual particles is increased. It becomes possible to suppress the destruction of the necking portion, thereby not only preventing the necking portion from being destroyed at the time of chemical formation, but also producing a wound element using this capacitor electrode foil Is also easier.

  Thus, the capacitor electrode foil according to the present embodiment can not only increase the surface area and expand the capacity, but also has excellent liquid impregnation properties and can increase the bonding strength of the necking portion. This produces an exceptional effect that it is also easy to produce a device having a shape.

  The electrode foil for capacitors according to the present invention has the effects that the capacity can be increased, the liquid impregnation property is excellent, and it is easy to produce a wound element, and is useful for capacitors in various fields. .

SEM photograph showing the configuration of an electrode foil for a capacitor according to an embodiment of the present invention SEM photo with enlarged main part of FIG. Characteristic diagram showing the pore size distribution of the capacitor electrode foil

Explanation of symbols

1 Base material 1a Vapor deposition layer

Claims (3)

It consists of a base material made of valve action metal foil and a valve action metal vapor deposition layer formed by vapor deposition on the surface of this base material, and this valve action metal vapor deposition layer has a frost columnar structure from the base material to the surface layer. Each pillar is a so-called sea grape-shaped electrode foil in which individual particles are branched into a plurality of pieces and joined together. The electrode foil for capacitors according to claim 1, wherein an aluminum foil is used as a base material made of a valve action metal foil. The electrode foil for capacitors according to claim 1, wherein aluminum is used as a vapor deposition layer of the valve metal.