JP4391677B2 - Aluminum alloy foil for electrolytic capacitor cathode - Google Patents

Description

【００２１】
得られた各電解コンデンサ陰極用アルミニウム合金箔に、以下の条件でエッチング処理を施して、未化成で以下に示す条件で静電容量（μＦ／ｃｍ²）を測定した。
〔エッチング処理〕
６ｗｔ．％塩酸＋０．５ｗｔ．％燐酸＋０．５ｗｔ．％蓚酸を含む水溶液（液温５０℃±１℃）中に、各電解コンデンサ陰極用アルミニウム合金箔を浸漬し、３０Ｈｚの正弦波交流により、見掛け電流密度０．２５Ａ／ｃｍ²で、２００秒間の交流電解エッチングを行った。
〔静電容量〕
エッチング処理を終えた未化成の各箔の各々２枚を対向させ、１３ｗｔ．％アジピン酸アンモニウム水溶液（液温３０℃±１℃）中に浸漬し、１２０Ｈｚの直列等価回路で、ＬＣＲメーターを用いて、静電容量（μＦ／ｃｍ²）を測定した。
そして、実施例３に係る電解コンデンサ陰極用アルミニウム合金箔の静電容量を基準（１００％）として、それとの比較で各電解コンデンサ陰極用アルミニウム合金箔の静電容量を、表２に示した。
【００２２】
更に、各電解コンデンサ陰極用アルミニウム合金箔に、以下の条件で折曲試験を行い、折曲強さ（回／ｃｍ）を測定した。
〔折曲強さ〕
上記のエッチング処理を終えた各箔を、大気中にて４００℃で５分間加熱処理を行った、加熱処理後の各箔を、ＪＩＳ Ｐ ８１１５「紙及び板紙のＭＩＴ試験機による耐折強さ試験方法」に準じて、ＭＩＴ型耐折試験機により、折曲強さ（回／ｃｍ）を測定した。
この結果を表２に示した。
【００２３】
【表２】

【００２４】
表２の結果から明らかなように、実施例に係る電解コンデンサ陰極用アルミニウム合金箔の場合、比較例のものに比べて、静電容量及び折曲強さの両方がバランス良く向上していることが分かる。
【００２５】
【発明の効果】
以上説明したように、本発明に係る電解コンデンサ陰極用アルミニウム合金箔は、交流エッチング処理によって、表面積が十分に拡大されると共に均一にエッチングされる。従って、得られた電解コンデンサ陰極箔は静電容量が大きく、単位面積当たり大容量のコンデンサを得ることができるという効果を奏すると共に、折曲強さが高く、コンデンサ加工時（巻回時等）において切断等のトラブルが少なく、作業性が良好になるという効果を奏する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aluminum alloy foil suitable for obtaining an electrolytic capacitor cathode foil having a high capacitance and a high bending strength.
[0002]
[Prior art]
The electrolytic capacitor electrode foil is manufactured by etching an aluminum alloy foil. Etching is performed in order to increase the capacitance by forming fine irregularities on the surface of the aluminum alloy foil and increasing the surface area of the foil. Therefore, in order to obtain an electrode foil for an electrolytic capacitor having a high capacitance, it is necessary to manufacture using an aluminum alloy foil having good etching characteristics. As the etching process, various etching methods are employed so that an etch pit suitable for the withstand voltage can be obtained. For example, it is preferable that tunnel-like etch pits are formed in the anode high-pressure foil, and sponge-like pits are formed in the anode low-pressure foil or the cathode foil. As the latter method, the AC electrolytic etching method is generally employed for the latter.
[0003]
Conventionally, various aluminum alloy foils having good AC etching characteristics have been proposed. For example, it has been proposed to improve etching characteristics by adding a predetermined amount of Mg, Zn, Ti, Ni or the like to an aluminum alloy foil (JP-A-2-51210, JP-A-3-130340). Publication, JP-A-5-82397). This proposed aluminum alloy foil is preferable because it is excellent in AC etching property and a high-capacitance cathode foil is obtained.
[0004]
On the other hand, the following has been proposed as an aluminum alloy foil that focuses on improving the bending strength of the obtained electrode foil rather than improving the capacitance. That is, Japanese Patent Application Laid-Open No. 10-287944 discloses an aluminum alloy foil for electrolytic capacitor anode low pressure containing less than 0.0002% Ti, less than 0.0002% V and 0.0002 to 0.001% B. Proposed. JP-A-6-220561 discloses an electrolytic capacitor containing about 0.00001 to 0.0001% Ti, about 0.00005 to 0.0005% V, and about 0.00005 to 0.0025% B. An aluminum alloy foil for anode low pressure has been proposed. Certainly, when the aluminum alloy foil is subjected to an AC etching treatment, an anode low-pressure foil having excellent folding strength and a certain capacitance can be obtained.
[0005]
[Problems to be solved by the invention]
However, when this electrolytic capacitor anode low-pressure aluminum alloy foil is directly used as a cathode aluminum alloy foil, it has been found that the cathode foil obtained by AC etching has insufficient capacitance. Therefore, the present inventors adjusted the content of Si and Fe in the aluminum alloy foil, and further increased the content of B, thereby providing a cathode foil with high electrostatic capacity and excellent bending strength. An aluminum alloy foil that can be obtained has been proposed (Japanese Patent Application No. 2000-150439).
[0006]
In the present invention, Al purity is 99.8% or more, Si: 0.02 to 0.08%, Fe: 0.02 to 0.08%, Ti: 0.00005 to 0.0005%, V: 0 0.005% to 0.0005%, B: 0.0025 to 0.01%, Cu: 0.003% or less, and other inevitable impurities, an aluminum alloy foil for electrolytic capacitor cathodes.
[0007]
As a result of further research, the inventors of the present invention added a predetermined amount of Mg and increased the content of Cu in the above-described invention, whereby a cathode foil having high capacitance and excellent bending strength was obtained. It has been found that an aluminum alloy foil that can be obtained is obtained. The present invention has been made based on such knowledge.
[0008]
[Means for Solving the Problems]
That is, the present invention is Cu: 0.2-1.0%, Si: 0.01-0.1%, Fe: 0.02-0.2%, Mg: 0.002-0.2%, Ti: 0.0005 to 0.05%, V: 0.0001 to 0.01%, B: 0.0001 to 0.01%, other inevitable impurities: 0.05% or less, Al: remaining. The present invention relates to a characteristic aluminum alloy foil for an electrolytic capacitor cathode. In the present specification, “%” indicating the alloy composition means “mass%”.
[0009]
The constituent elements and their contents of the aluminum alloy foil for electrolytic capacitor cathodes according to the present invention are as follows. Cu is 0.2 to 1.0%. If Cu is less than 0.1%, the etching characteristics deteriorate and the surface area cannot be increased, which is not preferable. On the other hand, if Cu exceeds 2.0%, over-dissolution tends to occur during etching, which is not preferable.
[0010]
Si is 0.01 to 0.1%. If Si is less than 0.01%, the number of Si precipitates decreases, the etching start point decreases, the etching property becomes poor, and it becomes difficult to obtain a high-capacity cathode foil, which is not preferable. If Si exceeds 0.1%, too many etching start points will occur, causing excessive dissolution during etching, and fine irregularities on the surface of the aluminum alloy foil once formed will drop, resulting in an increase in the surface area of the foil. Since it becomes difficult, it is not preferable.
[0011]
Fe is 0.02 to 0.2%. If the Fe content is less than 0.02%, the number of Fe precipitates decreases, the etching property becomes poor, and it becomes difficult to obtain a high-capacity cathode foil, which is not preferable. If Fe exceeds 0.2%, the presence of a large amount of Fe precipitates cannot be avoided and overdissolution occurs during etching, which is not preferable.
[0012]
Mg is 0.002 to 0.2%. When Mg is less than 0.002%, the amount of Mg bonded to Si decreases, and precipitation of simple Si or Al—Fe—Si compounds increases. For this reason, a plurality of potential differences are generated between the matrix and each compound, rather than an aluminum alloy foil in which only the Al—Fe compound is present, and this is not preferable because the possibility of over-dissolution during etching increases. If Mg exceeds 0.2%, the amount of Mg segregated on the surface of the aluminum alloy foil increases due to thermal diffusion, and overdissolution occurs during etching, which is not preferable.
[0013]
Ti is 0.0005 to 0.05%. If Ti is less than 0.0005%, uniform etching is difficult to be performed on the entire surface, and the bending strength is lowered. When Ti exceeds 0.05%, etching in the thickness direction of the aluminum alloy foil becomes poor, the surface area expansion effect is reduced, and it becomes difficult to obtain a cathode foil with high capacitance, which is not preferable.
[0014]
V is 0.0001 to 0.01%. If V is less than 0.0001%, uniform etching is difficult to be performed on the entire surface, and the bending strength is lowered. If V exceeds 0.01%, etching in the thickness direction of the aluminum alloy foil becomes defective, which is not preferable.
[0015]
B is 0.0001 to 0.01%. If B is less than 0.0001%, uniform etching is difficult to be performed on the entire surface, and the bending strength is lowered. If B exceeds 0.01%, excessive dissolution occurs during etching, which is not preferable.
[0016]
The aluminum alloy foil for an electrolytic capacitor cathode according to the present invention may contain several kinds of elements as inevitable impurities in addition to the above-described elements. Even in such a case, the total content of inevitable impurities must be 0.05% or less. If the total content of inevitable impurities exceeds 0.05%, it is not preferable because a local battery is formed with Al and over-dissolution may occur during etching.
[0017]
The aluminum alloy foil for an electrolytic capacitor cathode according to the present invention can be reasonably obtained by, for example, the following production method. That is, Cu: 0.2-1.0%, Si: 0.01-0.1%, Fe: 0.02-0.2%, Mg: 0.002-0.2%, Ti: 0.00. An ingot consisting of 0005 to 0.05%, V: 0.0001 to 0.01%, B: 0.0001 to 0.01%, other inevitable impurities: 0.05% or less, Al: the remainder, temperature 500 C.-620.degree. C., homogenization treatment for 20 hours or less, hot rough rolling and hot finish rolling, followed by cold rolling, at a plate thickness of 0.2-1.5 mm, temperature 360.degree. An intermediate annealing is performed under conditions of 480 ° C. for 20 hours or less, and then finish cold rolling is performed, so that an aluminum alloy foil for an electrolytic capacitor cathode having a desired thickness can be manufactured. An electrolytic capacitor cathode foil can be obtained by subjecting this aluminum alloy foil to an appropriate etching treatment.
[0018]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to an Example. In the present invention, an aluminum alloy foil having a specific elemental composition has good etching characteristics (both uniform etching and etching imparted to surface area enlargement), so it has high capacitance and high folding resistance. It should be interpreted as being based on the finding that a strong cathode foil is obtained.
[0019]
Examples 1-3 and Comparative Examples 1-6
Ingots (thickness 500 mm) having the elemental composition shown in Table 1 were prepared. And after performing the homogenization process on 580 degreeC conditions for 1 hour, it hot-rolled immediately and obtained the aluminum plate of thickness 3mm. This aluminum plate was cold-rolled to obtain an aluminum thin plate having a thickness of 0.4 mm. Then, this aluminum thin plate was subjected to intermediate annealing at a temperature of 450 ° C. for 10 hours, and then finish cold-rolled to obtain an aluminum alloy foil for an electrolytic capacitor cathode having a thickness of 0.05 mm.
[0020]
[Table 1]

[0021]
Each of the obtained aluminum alloy foils for electrolytic capacitor cathodes was subjected to an etching treatment under the following conditions, and the capacitance (μF / cm ² ) was measured under the following conditions without being formed.
[Etching treatment]
6 wt. % Hydrochloric acid + 0.5 wt. % Phosphoric acid + 0.5 wt. Each aluminum capacitor foil for electrolytic capacitor cathode is immersed in an aqueous solution containing 50% oxalic acid (liquid temperature 50 ° C. ± 1 ° C.), and an apparent current density of 0.25 A / cm ² is applied for 200 seconds by 30 Hz sinusoidal alternating current. AC electrolytic etching was performed.
[Capacitance]
2 sheets of each unformed foil that has been subjected to the etching treatment are opposed to each other, and 13 wt. It was immersed in an aqueous solution of ammonium adipate (liquid temperature 30 ° C. ± 1 ° C.), and the capacitance (μF / cm ² ) was measured using a LCR meter with a series equivalent circuit of 120 Hz.
Table 2 shows the capacitances of the aluminum alloy foils for electrolytic capacitor cathodes in comparison with the capacitance of the aluminum alloy foil for electrolytic capacitor cathodes according to Example 3 as a reference (100%).
[0022]
Furthermore, each aluminum capacitor foil for electrolytic capacitor cathodes was subjected to a bending test under the following conditions, and the bending strength (times / cm) was measured.
[Bending strength]
Each foil after the above etching treatment was heat-treated at 400 ° C. for 5 minutes in the atmosphere. Each foil after the heat treatment was subjected to JIS P 8115 “Folding strength of paper and paperboard by MIT testing machine” The bending strength (times / cm) was measured with a MIT type folding tester according to “Test method”.
The results are shown in Table 2.
[0023]
[Table 2]

[0024]
As is clear from the results in Table 2, in the case of the aluminum alloy foil for an electrolytic capacitor cathode according to the example, both the capacitance and the bending strength are improved in a balanced manner as compared with the comparative example. I understand.
[0025]
【The invention's effect】
As described above, the aluminum alloy foil for electrolytic capacitor cathode according to the present invention is etched uniformly while the surface area is sufficiently expanded by the AC etching process. Therefore, the obtained electrolytic capacitor cathode foil has the effect that the capacitance is large and a capacitor having a large capacity per unit area can be obtained, and the bending strength is high, and the capacitor is processed (when wound). There are few troubles, such as cutting | disconnection, and there exists an effect that workability | operativity becomes favorable.

Claims (1)

Cu: 0.2-1.0%, Si: 0.01-0.1%, Fe: 0.02-0.2%, Mg: 0.002-0.2%, Ti: 0.0005 Electrolytic capacitor cathode comprising 0.05%, V: 0.0001 to 0.01%, B: 0.0001 to 0.01%, other inevitable impurities: 0.05% or less, Al: balance Aluminum alloy foil for use.