JPH0154850B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to an aluminum alloy foil for an anode of an electrolytic capacitor, particularly an aluminum alloy foil for an anode. Problem of the Invention Since the capacitance of an electrolytic capacitor is proportional to the surface area of its electrodes, aluminum foil for electrodes used for such purposes generally has a surface area that can be expanded by electrochemical etching treatment. It can be measured. Therefore, the most important conditions that must be met are that the etching should be able to obtain as large an area expansion ratio as possible, have relatively little corrosion loss, and maintain good mechanical strength. be done. Means for Solving the Problems In order to meet the above demands, this invention
As a result of various experiments and research, it was discovered that extremely excellent etching characteristics could be obtained by adding a small amount of Mitsushi metal to aluminum electrode foil, and this was completed. Accordingly, the present invention is directed to an aluminum alloy foil for use in electrolytic capacitors, particularly for anodes, and is characterized by having an aluminum purity of 99.9% or more and containing 0.0003 to 0.0105% Mitsushi Metal. In this specification, all "%" means "% by weight". Generally, it is well known that aluminum foil used for the anode of an electrolytic capacitor is required to have a purity of 99.9% or more, and that 99.99% or more is particularly preferred. By using such high-purity aluminum foil as the anode foil, only a relatively small amount of Mitsushi metal is added in this invention.
This effect can be obtained by containing it in the range of 0.003 to 0.0105%. If the content is less than 0.0003%,
It was not possible to show the desired effect, and on the contrary,
If the content exceeds 0.0105%, the surface of the foil will melt, making it impossible to obtain the desired surface enlarging effect, and also reducing the mechanical strength of the foil. Therefore, in the aluminum foil for anode that is the object of this invention, the content of Mitsushi metal is 0.0001 to 0.0001.
Set within the range of 0.0105%. The reason why the capacitance can be increased by including a small amount of Mitsushi metal as described above is considered to be due to the following reason. In other words, Mitsushi Metal easily combines with impurity elements in aluminum foil, easily precipitates intermetallic compounds, and
This is thought to be due to the fact that it has a strong bond with oxygen and easily forms oxides, so these are densely dispersed in the foil material, effectively forming dense etching nuclei and further enhancing the etching effect. Note that, in the aluminum alloy foil for an anode according to the present invention, it is of course permissible that the foil contains other various elements as inevitable impurities. In addition, as a conventionally known technique, various trace elements are actively added in order to increase the area expansion ratio of aluminum electrode foil and maintain good mechanical strength. The scope of the invention also includes cases where such general forced addition elements are additionally included in addition to Mitsushimetal. Such elements include iron, copper, zinc, manganese, silicon, vanadium, titanium, strontium, lead,
Examples include tin, bismuth, boron, magnesium, indium, arsenic, silver, cadmium, thorium, zirconium, gallium, silicon, etc., and the content thereof is generally within the range of 0.00001 to 0.1%.
When these elements are contained, in addition to the effects due to the inclusion of Mitsushi Metal according to the present invention, the effects due to the inclusion of the above elements are simply expressed as a sum, and when a synergistic effect beyond that is expected. However, in any case, the present invention is included within the scope of the invention as long as the effect of the inclusion of Mitsushimetal is achieved. Effect of the invention This invention is based on having the above configuration,
When the aluminum alloy foil is etched, it is possible to significantly increase the surface area while maintaining good mechanical strength, thereby achieving the effect of further improving capacitance. It is something. Examples Next, examples of the present invention will be shown together with comparative examples. Aluminum alloys with various chemical compositions as shown in Table 1 were rolled to a thickness of 0.1 mm by a conventional method, and then annealed in an inert gas atmosphere to obtain Samples 1 to 7 of the present invention and Comparative Samples A to A. B was produced. Of these test samples, Samples 1 to 4 and A are based on 99.99% pure aluminum ingots, and Samples 5 to 7 and B are based on 99.9% pure aluminum ingots with various amounts of Mitsushi Metal added. It was manufactured by The above samples 1 to 7 and A to B were etched in a 3% hydrochloric acid aqueous solution at 75°C for 8 minutes through direct current at a current density of 15 A/dm ² and converted to 350 V. The capacitance was measured. The results of this measurement were as shown in the right column of Table 1.

【table】

[Table] As seen in the results shown in Table 1, the aluminum alloy foils of the present invention containing Mitsushi metal in the range of 0.0003 to 0.0105% (Samples 1 to 7) are different from the foils that do not contain it (Sample A). -B) A clear increase in capacitance was observed, and it was confirmed that the foil had excellent performance as an electrolytic capacitor anode foil.

Claims (1)

[Claims] 1. An aluminum alloy foil for an electrolytic capacitor anode, which has an aluminum purity of 99.9% or more and contains 0.0003 to 0.0105% Mitsushi Metal.