JPS6151817A - Aluminum electrode material for electrolytic condenser and method of producing same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an aluminum electrode for electrolytic capacitors and a method for manufacturing the same.

BACKGROUND OF THE INVENTION Aluminum foil used as an aluminum electrode material for electrolytic capacitors is required to have as large a surface f^ as possible and to have a large capacitance per unit volume. 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. Improvement of materials, improvement of etching methods to make the material larger, deeper, and thicker.
Research on the manufacturing process of foil (extensive research is being conducted).

Problems to be Solved by the Invention However, in practice, in the conventionally known etching technology J3, the locations where etching holes are generated are generally non-uniform;
In addition, if you try to make many etching holes, the etching holes may connect with each other and become coarse holes, or the surface of the aluminum foil will melt at the same time, reducing the mechanical strength of the foil by 10%, and the etching holes may be deep. Therefore, there is a problem that it is difficult to obtain the expected effect of increasing the area enlargement ratio.In particular, regarding the non-uniformity of the area where etching holes occur, However, it is difficult to avoid this because uneven etching bits occur during etching due to the precipitation of impurity atoms contained in the aluminum foil, the presence of gold intercalation compounds, crystal grain agglomerates, etc. .

The present invention solves these problems and makes it possible to uniformly form many deep etching holes while retaining and tightening the required mechanical strength in aluminum foil, and has an excellent surface area ratio, that is, capacitance. This invention was made with the intention of providing an aluminum electrode material for electrolytic capacitors that can be used as a material for electrolytic capacitors.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a method for forming etching holes, regardless of the presence of intermetallic compounds, crystal grain agglomerates, etc. The purpose of this method is to intentionally determine in advance the location where the pores occur, and by integrally adhering a resistant film that has many uniform pores to the surface of the aluminum foil in advance, the area corresponding to the pores is removed during the etching process. This method succeeded in intensively eroding the etching holes by using them as etching nuclei, thereby uniformly forming a large number of deep etching holes.

That is, one of the inventions relates to an aluminum electrode material for an electrolytic capacitor, and the surface of the aluminum foil is resistant to an electrolytic etching solution and has a large number of micropores that should not form etching nuclei. Another feature is that a film is integrally deposited. Another method for manufacturing this electrode material involves coating the surface of an aluminum foil with a resist and applying a photomask. The photoresist method, which involves the sequential implementation of mounting, exposure, and development steps, produces a resistant coating that is resistant to electrolytic etching solutions and has a large number of micropores for forming etching nuclei corresponding to the desired etching pattern. is characterized in that it is formed as a porous resist film.

The above-mentioned resistant coating is for preventing erosion of the surface of the aluminum foil except for the areas corresponding to micropores during etching, and therefore, it must be resistant to the electrolytic etching solution, i.e., it must be non-soluble. and must be corrosion resistant. In addition, the micropores provided in the resistant coating are for forming etching holes only in the corresponding part of the aluminum foil, so the arrangement, size, number, etc. of the micropores will depend on the arrangement, size, and quantity of the etching holes. This directly affects the final capacitance, mechanical strength, etc. of the aluminum foil. Therefore, it is necessary to fully consider this point when forming micropores.

The method for forming such a resistant film is not particularly limited in the present invention, but a photoresist method is preferably employed. The photoresist method forms a durable film as a resist film, and generally involves sequentially performing the steps of applying a resist to the surface of an aluminum foil, attaching a photomask, exposing, and developing. It is something that The photomask is for forming micropores in a desired etching pattern,
The portion where micropores are to be formed is a light-transmitting portion, and the rest is a light-shielding portion. The development process is for removing unnecessary resists 1 through irradiated with light through the light-transmitting part of the photomask during the exposure process.
: A porous resist film is patterned on the surface of the aluminum foil.

The electrode material according to the present invention manufactured in this way has its 1p
An electrochemical or chemical etching process is performed in an acid or alkaline bath. The etching solution used in the etching process is not particularly limited, and the etching liquid used in the etching process is known in the art.
A 2 to 15% hydrochloric acid aqueous solution, or an aqueous solution prepared by adding an acid such as chromic acid, sulfuric acid, or oxalic acid to the solution may be optionally used. Other etching processing conditions, i.e. liquid? r
All conventional etching processing conditions such as mN current density and etching time can be used as they are. By this etching treatment, while suppressing surface dissolution of the portion of the aluminum foil to which the resistant coating is attached, it is possible to intensively erode only the portions corresponding to the micropores, thereby making it possible to form deep and thick etching holes.

After the etching process, the aluminum foil is then
The resistant film adhering to the foil surface is removed using an alkaline solution or the like.

As described in detail of the invention, the aluminum electrode material according to the present invention and the aluminum electric conductor material manufactured by the present invention are provided with an electrolytic etching solution (resistant to it and capable of forming etching nuclei) on the surface of the aluminum foil. Since the resistant coating with a large number of micropores is integrally formed, the first layer suppresses surface dissolution of the portion of the aluminum foil where the resistant coating is attached during the subsequent etching process. As a result, many deep and thick etching holes can be uniformly formed in the aluminum foil. Therefore, the mechanical strength of the aluminum foil can be improved. It can be made into an ideal electrical conductor (water-use aluminum foil) with extremely high area expansion ratio, that is, an extremely large capacitance, without any damage, and as a result, aluminum electrolytic capacitors can be used. This will help realize further miniaturization, which is an important issue.Furthermore, it will improve the surface properties and other qualities that are uniquely required for aluminum foil in the conventional technology.
Since the aluminum foil used in the present invention has almost no material properties, it is possible to simplify and omit the manufacturing process of the aluminum foil, and to use a foil that is inexpensive in terms of material. This has the effect of reducing costs.

Further, in the method for manufacturing an aluminum electrode material for an electrolytic capacitor according to the present invention, since the above-mentioned resistant film is formed as a resist film by a photoresist method, the manufacturing operation can be performed relatively easily. It is possible to freely control the arrangement of micropores, large serrations, etc. in the resistant coating, and the etching pattern can be intentionally set arbitrarily, resulting in excellent performance that can provide an even higher area enlargement ratio. This makes it possible to manufacture electrode materials.

Example Next, examples of the present invention will be shown in comparison with comparative examples.

An annealed aluminum foil with a purity of 99.99% and a thickness of 0.1 mm was immersed in a resist solution at 30°C for 30 seconds.
A resist coating layer was formed on the surface of the foil by performing a preheating treatment of 0'CX for 15 minutes. Next, the light-shielding member has a diameter of 1. OI
A 2KW ultra-high-pressure mercury lamp was applied through a photomask made up of im transparent windows arranged at 1.0μ intervals.
Exposure was performed by irradiating for a minute. Then, add 3
After being immersed for 0 seconds and developed, a heat treatment was performed at 90"CX for 20 minutes to obtain a mold material according to the present invention in which a porous resist film was formed as a resistant film on the surface. The product name is rOHPRJ manufactured by Tokyo Ohka Kogyo Co., Ltd.
was used, and a developer manufactured by the same company under the trade name "○HPR developer" was used.

Etching solution; 5
W [%1p acid aqueous solution, temperature near 0''C, DC current density:
After performing etching treatment under etching conditions of 10A/dm and etching time of near minutes, 25°C, 5wt%
A resist stripping process was performed by immersing the resist in a sodium hydroxide aqueous solution for 2.1'l'.

The etched foil obtained above was placed in a 17I acid bath for 30 minutes.
After converting to 0V, 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 cum material as above and etching only under the same etching conditions.

The results were as shown in the table below.

As shown in the results in the table above, according to the present invention, only the portions corresponding to the many micropores uniformly provided in the resistant coating of the aluminum foil can be deeply eroded as etching nuclei. , it was possible to realize a clear improvement effect on the capacitance and tensile strength of the aluminum foil.

that's all

Claims (2)

[Claims] (1) Aluminum for electrolytic capacitors, which is formed by integrally adhering to the surface of aluminum foil a resistant coating that is resistant to electrolytic etching liquid and has a large number of micropores that should form etching nuclei. Electrode material. (2) A desired etching pattern that is resistant to electrolytic etching solution is formed on the surface of the aluminum foil using a photoresist method that involves the sequential implementation of resist coating, photomask attachment, exposure, and development steps. A resistant coating with many micropores for etching nucleus formation corresponding to
A method for producing an aluminum electrode material for an electrolytic capacitor, the method comprising forming an aluminum electrode material as a porous resist film.