JPH06330213A - Aluminum foil material for electrode of electrolytic condensor excellent in surface area scaling up effect - Google Patents

Abstract

PURPOSE:To obtain the Al foil material for the electrode of the electrolytic condensor which exhibits excellent sruface area scaling up effect by forming the surface diffuse layer containing the first diffusing component of Pb, etc., and the second diffusing component of Fe, etc., each in a specified amount. CONSTITUTION:The surface diffuse layer containing at the surface part 0.001-0.25wt.% first diffusing component consisting of 1 kind or >=2 kinds among Pb, Bi, In and Sn and 0.001-1wt.% second diffusing component consisting of 1 kind or >=2 kinds among Fe, Co, Cr, Mn and Zr is formed on the surface part of the foil material consisting essentially of the Al of >=99.9% purity at the central part. In this way, the Al foil material for the electrode of the electrolytic condensor exhibiting excellent surface diffusion effect by etching treatment can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an etching process,
The present invention relates to an aluminum foil material for an electrode of an electrolytic capacitor, which exhibits an excellent surface area expanding effect.

[0002]

2. Description of the Related Art Conventionally, an aluminum foil material made of pure Al having a purity of 99.9% by weight or more is generally used as an electrode of an electrolytic capacitor, and the larger the surface area of the electrode, the higher the electrostatic capacity. Since the obtained surface area, that is, the surface area is proportional to the capacitance, for the purpose of obtaining a much higher surface area during the etching treatment, for example, Japanese Patent Publication No.
As described in JP-A-2-42370 and JP-A-1-128419, Pb having a surface area expanding action on the surface portion of a foil material made of Al having a purity of 99.9% by weight or more in the central portion. , Bi, In, and Sn, etc., or 0.001 to 0.2% by weight.
An aluminum foil material formed by forming a surface diffusion layer containing it at a ratio of is also proposed.

[0003]

On the other hand, in recent years, there has been a strong demand for miniaturization and high performance of electrolytic capacitors, and along with this, it is desired to further increase the surface area of electrodes. Under the present circumstances, the aluminum foil material cannot be formed with a sufficient surface area to satisfy the above requirements by etching.

[0004]

Therefore, the present inventors have
From the above viewpoint, as a result of research to develop an aluminum foil material for an electrode of an electrolytic capacitor capable of further enlarging the surface area by etching, as a result, Pb, Bi, In, and Sn on the surface part were Fe, Ni, Co, C is further added to the surface diffusion layer of a conventional aluminum foil material having a surface diffusion layer composed of one or more of them (hereinafter, these are collectively referred to as a first diffusion component).
When one or more of r, Mn, and Zr (hereinafter collectively referred to as a second diffusing component) is diffused and contained in an amount of 0.001 to 1% by weight in the outermost surface portion of the foil material. The present inventors have obtained research results that the coexistence of these first and second diffusive components causes the surface of the foil material to have a further enlarged surface area by etching.

The present invention has been made based on the above-mentioned research results, and the central portion has a substantial purity of 99.
The content of the first diffusion component in the outermost surface portion of the surface of the foil material made of Al of 9% by weight or more is 0.001 to 0.
25% by weight, the content of the second diffusion component is 0.0
It is characterized by an aluminum foil material for electrodes of an electrolytic capacitor, which is formed by forming a surface diffusion layer of 0 to 1% by weight and exhibits an excellent surface area expansion effect by etching treatment.

The aluminum foil material of the present invention contains the first diffusion component in a proportion of 0.1 to 1.5 ppm,
An Al alloy melt having a composition with the balance consisting of Al and unavoidable impurities is prepared and made into an ingot by an ordinary casting method such as a semi-continuous casting method. Accordingly, cold rolling is performed while applying intermediate annealing to form an Al alloy foil material having an average layer thickness of 50 to 200 μm, and the second diffusion is performed on the surface of the Al alloy foil material by, for example, an ion plating method. A thin film of the component is formed to a predetermined thickness, or one or more of the second diffusion component such as acetylacetone, stearic acid, and naphthenate is usually added in an amount of 0.1 to 0.1.
An IPA solution or a mineral spirit solution containing about 0.5% by weight is applied to a predetermined thickness, and the Al alloy foil material in this state is heated and maintained at a temperature of 530 to 620 ° C. in a non-oxidizing atmosphere. It is desirable to manufacture by performing a heat treatment. By the heat treatment, the first diffusion component uniformly contained in the Al alloy foil raw material diffuses and moves to the foil material surface portion, and the foil material central portion is 99. Al having a purity of 9% by weight or more, while the second diffusion component existing on the surface of the Al alloy foil material also diffuses inward from the surface, and the surface portion is surface-diffused by the first and second diffusion components. A layer is formed, and in this case, the content of the first and second diffusion components in the outermost surface portion of the foil material is the content of the first diffusion component in the Al alloy foil material, the heating temperature, the heating time, etc. Controlled by Door can be.

Next, in the aluminum foil material of the present invention, the reasons why the contents of the first and second diffusion components and the Al purity of the central portion of the foil material are limited as described above will be explained. That is, the content of either the first or second diffusion component in the outermost surface portion of the foil material is the first diffusion component: 0.001.
Less than 0.001% by weight and second diffusion component: If less than 0.001% by weight, the desired excellent surface area-enlarging effect cannot be exerted, while the content of the first diffusion component exceeds 0.25% by weight. In particular, when the thickness of the foil material is relatively thin, for example, around 50 μm, the etching progresses deep inside the foil material in the presence of the second diffusion component, which leads to a decrease in the strength of the foil material. Even if the content of the second diffusing component exceeds 1% by weight, the effect of increasing the surface area is not further exhibited. Therefore, the contents of the first and second diffusing components are 0.001 to 0.25% by weight and 0, respectively. It was defined as 0.001 to 1% by weight. Further, if the Al purity of the central portion of the foil material is less than 99.9% by weight, the strength and electrical characteristics required for the electrode of the electrolytic capacitor cannot be maintained, so that the purity is 99.9% by weight or more. I decided.

[0008]

EXAMPLES Next, the aluminum foil material of the present invention will be specifically described by way of examples. Pure A used as a raw material in a normal low frequency induction melting furnace: 99.99% by weight of pure A
1: 5 kg of each was melted, and the first diffusion component was added to this in a ratio shown in Table 1, and a semi-continuous casting method was used to form an ingot with dimensions of 40 mm x 180 mm in cross section and 250 mm in length. In this ingot, both sides were surface-cut to a thickness of 0.5 mm, both were hot-rolled at a hot-rolling start temperature of 520 ° C. to form a hot-rolled sheet having a thickness of 6 mm, Subsequently, under normal conditions, cold rolling is performed while optionally adding intermediate annealing to form two parts of each of the Al alloy foil materials A to J having the thickness shown in Table 1, respectively. Then, on the surface of a part of each of these Al alloy foil materials A to J, the second diffusion component thin film is formed in a predetermined thickness under normal conditions using the ion plating method with the combination shown in Table 2. Forming the second diffusion component thin film and Al alloy foil without the formation thereof The A-J, likewise the invention the foil material by heat treatment under the conditions shown in Table 2 1-1
0 and conventional foil materials 1 to 10 were manufactured.

Next, with respect to various foil materials obtained as a result, the outermost surface portion, that is, the depth from the surface: 0.05 μm
The content of the first diffusing component at the position and the Al purity of the central portion were measured, and for the foil materials 1 to 10 of the present invention, the content of the second diffusing component at the outermost surface portion was also measured. The results of these measurements are shown in Table 3. In addition, in Table 3, water is added in a ratio of 1 mol of hydrochloric acid: 1 mol and sulfuric acid: 3 mol with respect to 8 l.
Immersion in mixed acid water solution at 0 ℃, current density: 0.6A / c
The results obtained by measuring the electrostatic capacity at a formation voltage of 250 V in the state where the etching treatment was performed under the conditions of m ² and time: 40 seconds are also shown.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

From the results shown in Table 3, the foil material 1 of the present invention was obtained.
Nos. 10 to 10 are conventional foil materials for a surface diffusion layer containing only the first diffusion component by coexisting the second diffusion component together with the first diffusion component in the surface diffusion layer formed on the surface portion. It shows a large electrostatic capacitance as compared with 1 to 10, and it is clear that the effect of increasing the surface area by the etching treatment is excellent. As described above, the aluminum foil material of the present invention exerts an excellent effect of increasing the surface area by the etching treatment, so that when it is used as an electrode of an electrolytic capacitor, it greatly contributes to downsizing and high performance. It is a thing.

Claims (1)

[Claims] 1. Purity substantially in the center: 99.9% by weight
The content of the first diffusion component made of one kind or two or more kinds of Pb, Bi, In, and Sn in the outermost surface portion is 0.001 to 0.
A surface diffusion layer containing 25% by weight of 0.001 to 1% by weight of the second diffusion component composed of one or more of Fe, Ni, Co, Cr, Mn, and Zr was formed. This is an aluminum foil material for electrodes of electrolytic capacitors that has an excellent effect of increasing the surface area.