JPH0116898B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aluminum alloy foil for electrolytic capacitor electrodes. Aluminum foils used as electrodes for electrolytic capacitors are generally subjected to electrochemical etching treatment in solutions such as hydrochloric acid and salt solutions in order to expand their effective surface area and increase capacitance per unit volume. administered. Therefore, in order to improve the performance of electrolytic capacitors, as the foil material mentioned above,
It is required that the etching process be able to obtain as large an area enlargement ratio as possible. As a result of various experiments and research in order to meet the above-mentioned demands, this invention has resulted in an aluminum foil for electrolytic capacitor electrodes that has extremely excellent etching properties in an aluminum-based alloy containing zinc in coexistence with a trace amount of manganese. I discovered that
This is the completed version. That is, the electrode foil for electrolytic capacitors according to the present invention contains 0.00001 to 0.01% zinc and 0.00005% manganese.
Contains ~0.005% or additionally 0.0005~0.01 copper
%, with the remainder consisting of 99.9% or more of aluminum and unavoidable impurities. In this specification, all "%" means "% by weight". The inclusion of zinc in the foil makes it possible to significantly increase the number of etching holes and to distribute them uniformly. In order to achieve this effect to a sufficiently satisfactory degree, it is necessary that the content be at least 0.00001% or more. However, on the other hand, if too much zinc is contained, the surface of the foil will melt and the desired effect of enlarging the surface area by etching cannot be obtained, and the mechanical strength of the foil will also decrease. It should not be included. Therefore, the zinc content is limited to a range of 0.00001 to 0.01%. Furthermore, manganese has the effect of increasing the cubic orientation of the etching holes and extending the holes mainly in the thickness direction of the foil. In order to achieve this effect to the desired degree, the content of manganese should be 0.00005% or more, but excessive addition, that is, containing more than 0.005%, will reduce the leakage current after formation. This is not desirable because it makes it large. Moreover, the inclusion of copper thereby further increases the effect of the addition of zinc and makes the etching effect even higher. This effect is not sufficiently exhibited at a content of less than 0.0005%. However, when the content exceeds 0.01%, as in the case of excessive addition of zinc, surface dissolution of the foil occurs, and the desired effect of enlarging the surface area by etching cannot be obtained. In addition to the inclusion of zinc, the coexistence of manganese or the coexistence of manganese and copper can have a synergistic effect on increasing the area expansion ratio of the foil. On the other hand, it is well known that aluminum foil materials for electrolytic capacitor electrodes generally require an aluminum purity of 99.9% or higher, and in particular
It goes without saying that 99.99% or more is preferable. Therefore, it is naturally permissible for the aluminum alloy foil according to the present invention to contain other elements as inevitable impurities in addition to zinc, manganese, and copper. Examples Next, examples of the present invention will be shown together with control examples. Zinc, copper, and manganese are added to aluminum ingots with aluminum purity of 99.99%, and those with various contents and those with no additives are rolled to a thickness of 0.1 mm.
This was annealed at high temperature in an inert gas atmosphere, and these were used as test materials. This was electrolytically etched in a 3.5% hydrochloric acid aqueous solution at 80°C for 8 minutes with a direct current of 15 A/dm ² , and after chemical formation at 380 V in an ammonium borate solution, each capacitance was determined. It was measured. The results were as shown in Table 1 below.

[Table] *: Comparative alloy As is clear from the results in the table above, the aluminum alloy foil of the present invention can significantly increase its surface area through etching treatment.
As a result, a clear increase in capacitance can be obtained, and when used as an electrolytic capacitor electrode, excellent performance can be obtained.

Claims (1)

[Claims] 1. An aluminum alloy foil for an electrolytic capacitor electrode, containing 0.00001% to 0.01% zinc and 0.00005% to 0.005% manganese, with the balance being 99.9% or more aluminum and inevitable impurities. 2. An aluminum alloy foil for electrolytic capacitor electrodes, containing 0.00001-0.01% zinc, 0.00005-0.005% manganese, and 0.0005-0.01% copper, with the balance being 99.9% or more aluminum and irreplaceable impurities.