JP2666912B2 - Aluminum alloy for electrolytic capacitor electrode foil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy for electrode foils of electrolytic capacitors, and more particularly to an aluminum alloy for anode foils.

[0002]

2. Description of the Related Art An aluminum electrode foil for an aluminum electrolytic capacitor is generally subjected to an electrical or chemical etching treatment in order to increase its effective surface area and increase the capacitance per unit volume. Therefore, it is desired that the aluminum foil used as the electrode foil can have as large an area expansion ratio as possible by etching, and thus can increase the capacitance. Further, in order to make the electrode foil thinner and to reduce the size and weight of the capacitor and further reduce the cost, the corrosion loss is small in relation to the enlargement ratio, and excellent mechanical strength can be maintained. It is desired.

[0003] Conventionally, in order to satisfy the above requirements, generally, high-purity Al has been used as a material for an aluminum electrode foil. However, there is a disadvantage that the mechanism of dissolution of Al at the time of etching is varied due to the variation of impurities contained only by securing the Al purity, and a stable surface area and mechanical strength cannot be obtained.

[0004] Conventionally, as an aluminum alloy for an electrode foil, which has been improved in terms of an increase in the area coverage and good maintenance of mechanical strength, Zn: 0.1 to 100 ppm and Mn: 0.5 to
Contains 50ppm or Cu: 5-100p
pm, an alloy for electrode foil comprising 99.9% or more of aluminum and unavoidable impurities has been proposed (Japanese Patent Publication No. 1-16898), and it has been confirmed that the effect can be achieved appropriately. ing.

It is an object of the present invention to provide an aluminum alloy for an electrode foil of an electrolytic capacitor, which further improves the above and further improves the effect of increasing the surface area by etching and the effect of maintaining strength.

[0006]

In order to achieve the above object, the inventor has conducted various experiments and researches, and as a result, high purity Al has been obtained.
In the base metal, there is a combination and composition range of elements necessary for optimal formation of an etching nucleus, and it has been found that the presence of such an element enables formation of fine and deep etching pits while suppressing local dissolution. It was completed.

That is, according to the present invention, the purity of aluminum is 99.9% or more, Zn: 1 to 100 ppm, M
n: 1 to 50 ppm, Cu: 5 to 100 ppm, Fe:
5 to 100 ppm, Si: 5 to 100 ppm, Ga: 5
~100ppm, Pb: contains 0.05~ 5 ppm,
Alternatively, further, Mg, B, V, Ti, Zr, Ni, Cr
And P: An aluminum alloy for an electrode foil of an electrolytic capacitor, characterized by containing one or more of 0.5 to 25 ppm each. In the above description, the purity of aluminum is limited to 99.9% or more, and if less than 99.9%, Zn and M described below are used.
This is because the effect of increasing the capacitance of the foil cannot be obtained even when an element that forms an etching nucleus such as n is contained.

[0008] Zn (zinc), Mn (manganese), Cu
Since (copper), Fe (iron), Si (silicon), Ga (gallium), and Pb (lead) contain all of these, in the etching process for increasing the surface area, the etching nucleus, in other words, the etching starts. There is an effect that the number of points can be increased appropriately, and thereby the surface expansion rate can be improved and the capacitance can be increased. However, if at least one of the elements is less than the lower limit value, the above effect is insufficient, and the enlargement ratio and the capacitance cannot be increased. On the other hand, if at least one of the elements exceeds the upper limit, the number of etching start points becomes too large, causing excessive surface dissolution at the time of etching. As a result, not only a sufficient surface area is not obtained, but also the mechanical loss due to an increase in corrosion weight loss increases. The target strength also deteriorates. Particularly suitable contents are Zn: 2-40 ppm, Mn: 1-25 ppm, C
u: 8 to 40 ppm, Fe: 7 to 60 ppm, Si: 1
0 to 60 ppm, Ga: 5 to 40 ppm, Pb: 0.1
３3 ppm.

Also, Mg (magnesium), B (boron), V (vanadium), Ti (titanium), Zr (zirconium), Ni (nickel), Cr (chromium), P
(Phosphorus) does not significantly affect the electrical performance of the electrode foil, but rather can achieve a beneficial effect in improving the strength of the foil. In the present invention, (phosphorus) is evaluated as mutually equivalent. You. Therefore, a predetermined effect can be obtained by containing one or more of these elements, but the content of each element is 0.5 ppm.
If it is less than 25 ppm, the above effect is poor, and if it exceeds 25 ppm, the amount of surface dissolution of the foil at the time of etching is increased, and the strength is rather deteriorated. The most preferable content range of each element is about 0.5 to 5 ppm.

The other impurity elements are included in the 99.9% aluminum purity range. Production of the aluminum foil according to the present invention into the electrode foil of the electrolytic capacitor may be performed according to a conventional method, for example, after casting a slab from a molten aluminum by a vertical or horizontal semi-continuous casting method,
This slab may be formed into a foil having a thickness of about 30 to 150 μm by hot rolling, cold rolling, and foil rolling. The foil thus manufactured is generally subjected to an electrochemical or chemical etching treatment after being softened by an annealing process or without being softened, so that the effective surface area of the foil is enlarged to obtain an electrolytic capacitor electrode foil.

The electrode foil may be either an anode foil or a cathode foil, but is preferably used as an anode foil requiring high Al purity because the Al purity is 99.9% or more.

[0012]

According to the aluminum alloy for an electrolytic capacitor electrode according to the present invention, it is possible to form a large number of fine and deep etching pits while suppressing local melting at the time of etching. As is apparent, it is possible to provide an electrode foil having a large capacitance. In addition, by suppressing local dissolution, the weight loss due to corrosion can be reduced as much as possible in relation to the surface area, and the mechanical properties can be excellent.

[0013]

Next, an embodiment of the present invention will be described.

A slab was cast by a semi-continuous casting method from a molten aluminum adjusted to the component amounts shown in Table 1 below, and subjected to soaking, hot rolling, cold rolling, and foil rolling to a thickness of 90 μm. Of various foils. Next, these foils are subjected to electrolytic etching under the following conditions,
The corrosion weight loss due to etching was determined.

[Etching conditions] Electrolyte: 5% hydrochloric acid + 0.3% phosphoric acid + 0.1% nitric acid Temperature: 55 ° C. Current: 25 A / dm ² · 60 Hz AC time: 10 minutes After being converted to 20 V, the capacitance was measured. Table 1 shows the results. Note that the capacitance was measured for the sample No. 13 is expressed as a relative comparison when the capacitance is 100%.

[0016]

[Table 1]

As is clear from the results shown in Table 1, it was confirmed that the alloy of the present invention can be used as an aluminum electrode foil having a large capacitance. Moreover, it is understood that the corrosion weight loss is small.

Continuation of the front page (72) Inventor Masashi Sakaguchi 6, 224 Kaiyama-cho, Sakai-shi, Osaka Showa Aluminum Co., Ltd. (56) References JP-A-63-288008 (JP, A) JP-A-1-309938 ( JP, A) JP-A-2-270928 (JP, A) JP-A-53-114059 (JP, A) JP-A-58-1046 (JP, A) JP-B-1-16898 (JP, B2)

Claims (2)

(57) [Claims] 1. Zn: 1 to 100 ppm Mn: 1 to 50 ppm Cu: 5 to 100 ppm Fe: 5 to 100 ppm Si: 5 to 100 ppm Pb: 0.05 to 5 ppm, the balance being aluminum Aluminum alloy for electrode foil of electrolytic capacitor consisting of 99.9% or more and inevitable impurities. 2. Zn: 1 to 100 ppm Mn: 1 to 50 ppm Cu: 5 to 100 ppm Fe: 5 to 100 ppm Si: 5 to 100 ppm Ga: 5 to 100 ppm Pb: 0.05 to 5 ppm, and Mg , B, V, Ti, Zr, Ni, C
r and P: Aluminum alloys for electrolytic capacitor electrode foils each containing one or more of 0.5 to 25 ppm, and the balance consisting of 99.9% or more of aluminum and inevitable impurities.