JPH0528486B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a method of manufacturing an aluminum electrode material for an electrolytic capacitor. BACKGROUND OF THE INVENTION Aluminum foil used as an aluminum electrode material for electrolytic capacitors is required to have as large a surface area as possible and a large capacitance per unit area. For this reason, the effective surface area of the aluminum foil is generally expanded by electrochemical or chemical etching treatment, and etching holes are also added to increase the area expansion ratio as much as possible. In order to make the foil thicker, deeper, and thicker, various studies are being conducted, including improving materials, improving etching methods, and researching the manufacturing process of foil. Problems to be Solved by the Invention However, in practice, in the conventionally known etching techniques, the locations where etching holes are generated are generally non-uniform, and when attempting to increase the number of etching holes, the etching holes communicate with each other. Not only will the mechanical strength of the foil be impaired due to formation of coarse pores and melting of the surface of the aluminum foil will proceed at the same time, but the etching holes will not be deep enough, so the results are not fully expected. The problem was that it was difficult to obtain the effect of increasing the area expansion ratio. The present invention solves these problems and makes it possible to uniformly form a large number of deep etched holes while maintaining the necessary mechanical strength in aluminum foil, and has an excellent surface area ratio, that is, capacitance. The purpose of this work was to obtain an aluminum electrode material for electrolytic capacitors that could be used as an aluminum electrode material for electrolytic capacitors. Means for Solving the Problems For this purpose, the present invention applies a coating material that is resistant to etching treatment to the surface of an aluminum foil, and then partially removes the coating material using a laser to coat the surface of the aluminum foil. It is characterized by integrally depositing a resistant film that is resistant to etching treatment and has a large number of micropores for forming etching nuclei, thereby allowing the site where etching holes will occur to be determined in advance. The present invention has succeeded in manufacturing an electrode material that enables erosion of only the portions of the aluminum foil corresponding to the micropores during the etching process, thereby uniformly forming a large number of deep etching holes. The coating material is for forming a resistant film on the surface of the aluminum foil, and this resistant film is
When performing electrochemical or chemical etching treatment as described below, or dry etching treatment such as reactive ion etching, the surface of the aluminum foil is not eroded except for the portion corresponding to the micropores removed by the laser. This is to prevent this. Therefore, the coating material and therefore the resistant coating must by its nature be resistant to the etching process, i.e., in the case of electrochemical or chemical etching, it must be insoluble and insoluble in the electrolytic etching solution. be corrosion resistant;
In addition, dry etching requires that the material be invulnerable to ions and the like. An example of such a coating material is a commercially available resist ink for semiconductor photomasks. The coating thickness of the coating material, and thus the coating thickness of the resistant coating, is not particularly limited, as long as it is thick enough to prevent dissolution or erosion of the aluminum foil surface other than the portion corresponding to the micropores during etching. Further, it is appropriately set in consideration of the workability of removing the film after etching, etc. Further, as for the method of applying the coating material, any known method such as a roll coater method or a dipping method may be employed. Depending on the covering material,
After application, hardening treatment such as baking may be performed. Partial removal of the coating material by laser is performed in order to form micropores for forming etching nuclei in the coating material in a desired etching pattern, and is carried out by irradiation with a laser beam. Types of lasers include mainly processing lasers, such as carbon dioxide lasers and argon lasers. The size of the micropores can be arbitrarily set, and the arrangement thereof is not limited either, such as a vertical and horizontal arrangement, a zigzag arrangement, or any other arrangement. This laser removal operation completes the formation of a porous resistant film on the surface of the aluminum foil. The electrode material according to the present invention manufactured in this way includes:
Thereafter, an electrochemical or chemical etching treatment in an acid or alkaline bath, or a dry etching treatment such as reactive ion etching is performed. The etching solution used in the former etching process is not particularly limited, and may be a known 2 to 15% hydrochloric acid aqueous solution, or an aqueous solution to which an acid such as chromic acid, sulfuric acid, or oxalic acid is added. etc. may be adopted and used at will. All other etching processing conditions, ie, liquid temperature, current density, etching time, etc., can be employed as they are, as are conventionally known etching processing conditions. Also, when performing ion etching treatment, conventionally known treatment conditions can be used as they are. By these etching treatments, while suppressing surface dissolution or erosion of the portion of the aluminum foil to which the resistant film is attached, it is possible to intensively erode only the portions corresponding to the micropores, making it possible to form deep and thick etching holes. After the etching process, the aluminum foil is
Subsequently, the resistant film adhering to the foil surface is removed using an alkaline solution or the like to complete the aluminum electrode. Effects of the Invention As explained above, according to the present invention, after coating the surface of the aluminum foil with a coating material that is resistant to etching treatment, the coating material is partially removed using a laser, so that the surface of the aluminum foil is coated with a coating material that is resistant to etching. As a result of being able to manufacture an aluminum electrode material on which a resistant film with a large number of micropores is integrally adhered, surface dissolution or erosion of the resistant film attached part of the aluminum foil can be avoided during the subsequent etching treatment applied to the electrode material. This makes it possible to intensively erode only the portions corresponding to the micropores as etching nuclei while preventing this by the film layer.
Therefore, as a result, it is possible to uniformly form a large number of deep and thick etching holes in the aluminum foil, and it is possible to form an electrically It becomes possible to provide an ideal aluminum electrode with excellent characteristics, and it becomes possible to achieve further miniaturization, which is an important issue for aluminum electrolytic capacitors.
Furthermore, the surface characteristics and other quality (material) characteristics that are strictly required for aluminum foil in the conventional technology are almost unnecessary for the aluminum foil used in the present invention, so the manufacturing process of the aluminum foil can be simplified and omitted. By using a foil that is easy to use and is inexpensive in terms of material, it is possible to reduce costs. Moreover, in this invention, since the formation of the micropores is performed using a laser, the formation operation can not only be performed accurately and quickly, but also
Since the arrangement, size, etc. of the micropores can be freely controlled, it is possible to manufacture an electrode material with excellent performance that can provide an even higher area expansion ratio. Examples Next, examples of the present invention will be shown in comparison with comparative examples. A resist ink made of alkali-removable acrylic resin is applied to the surface of annealed aluminum foil with a purity of 99.99% and a thickness of 0.1 mm using a roll coater method.
After coating to a thickness of 5 μm, the resist was cured by baking at 160° C. for 5 minutes to form a resist coating layer on the surface.
Next, using an argon laser, the beam diameter was 1 μm.
By removing the resist film at a removal interval of 1 μm, an electrode material according to the present invention having a resistant film in which micropores with a diameter of 1 μm were formed in a staggered arrangement at 1 μm intervals was obtained. The electrode material obtained through the above process was subjected to etching treatment under the following conditions: etching solution: 5wt% hydrochloric acid aqueous solution, temperature: 70°C, DC current density: 10A/dm ² , etching time: 7 minutes. rear,
The resist was removed by immersion in a 1 wt % aqueous sodium hydroxide solution for 2 seconds at room temperature. The etched foil obtained above was placed in a boric acid bath.
After converting to 300V, the capacitance and tensile strength of the foil were measured. On the other hand, this result was compared with that of an aluminum foil (comparative example) using the same aluminum material as above and etching only under the same etching conditions. The results were as shown in the table below.

[Table] As shown in the above results, according to the present invention, only the portions corresponding to the many micropores uniformly provided in the resistant film on the surface of the aluminum foil are etched deeply as etching nuclei. By obtaining the apparent capacitance of the aluminum foil,
It was possible to realize the effect of improving tensile strength.

Claims (1)

[Claims] 1. After applying a coating material that is resistant to etching treatment to the surface of an aluminum foil, the coating material is partially removed using a laser to coat the surface with
A method for manufacturing an aluminum electrode material for an electrolytic capacitor, which comprises integrally depositing a resistant film that is resistant to etching treatment and has a large number of micropores for forming etching nuclei.