JPS58116717A - Method of producing aluminum electrode foil - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an aluminum electrode foil used as an anode foil and/or a cathode foil in an aluminum electrolytic capacitor.

In general, an aluminum electrolytic capacitor has an anode formed by forming an anodized film on a smooth or roughened (etched) aluminum foil with an external terminal, and a roughened aluminum foil with an external terminal, inside an aluminum case or a resin case. The capacitor element is housed with a cathode foil made of aluminum foil and passed through kraft paper or manila-linen mixed paper.
The structure is sealed with rubber, rubber-lined baking material, or resin material. In order to economically manufacture and downsize such aluminum electrolytic capacitors, it is essential to improve the surface area expansion rate by roughening the raw aluminum foil, and this is already well known. be.

Conventionally, a number of methods have been published in literature, academic journals, capacitor research groups, etc. as methods for roughening raw aluminum foil and improving its surface area expansion rate, but the main methods will be described below.

(1) Hydrochloric acid or common salt is used as the etching liquid, and the surface area expansion rate can be increased by adding various acids.
How to do it.

(2) A method of improving the surface area expansion rate by using a direct current power source, a single power source of various pulsating wave power sources (including from a sine wave to a rectangular wave), or a combination of these power sources as a power source.

(3) A method of improving the surface area expansion rate by combining various etching solutions and various power sources.

(4) During each roughening process of the raw aluminum foil, a thermal oxide film or an anodic oxide film is generated to suppress the dissolution of the fine roughened parts formed in the initial stage, and to repair the defective parts of the film in the next step. A method of improving the surface area expansion rate by effectively roughening the surface in the surface roughening step.

In other words, as a method for improving the surface area expansion rate of aluminum foil, as described above, a combination of etching solution composition, selection of power supply, and surface roughening process is generally used.

However, the main roughening mechanism in conventional methods is
When a pulsating wave power source is used as a power source, depending on the properties of the acid added while roughening the surface, an extremely thin film is formed and the surface is roughened from the defective parts of the film, or the surface is roughened in the middle of the roughening process. The purpose is to suppress surface solubility by forming an oxide film.

By the way, the purpose of the present invention is to obtain a surface area expansion rate even larger than that of the conventional surface area expansion rate. The present invention provides a method for manufacturing aluminum electrode foil using a surface roughening process.

Usually, the purity used as anode foil is 99.99 to 9.
9.98% raw aluminum foil, foil thickness 50~1
It is 20 μm. In the present invention, the foil thickness is 200 to 400.
Using raw aluminum foil in the state of μ- foil, first, preliminary roughening is carried out, dechlorination treatment is performed as necessary, and then rolling is performed to obtain the final desired foil thickness of 50 to 120 μ-.
Next, a tempering treatment is performed in accordance with the surface roughening conditions, and full-scale surface roughening is carried out by electrochemical means, which is a conventional technical means. In other words, the feature of the present invention is that a preliminary surface roughening process is provided during the rolling process of the aluminum foil.

The present invention will be explained in detail below. Example 1 is for medium and high pressure (
160-600V) An example of creating an anode foil used in an electrolytic capacitor is shown. Examples 2 and 3 are for medium and low pressure (6,
3-160V) An example of creating an anode foil used in an electrolytic capacitor is shown.

[Example 1] A raw aluminum foil with a foil thickness of 400 μm is washed with a surfactant and annealed in a vacuum state at 350° C. for 6 hours. next,
liquid! ! Current density 5001A/c♂, electricity amount 3001A・1 in 80℃ hydrochloric acid e, owt% etching solution
Preliminary surface roughening treatment is performed using a DC power source of n/cj'. Thereafter, dechlorination treatment is performed for 1 minute using a 3 wt % boric acid solution at a temperature of 85°C. Subsequently, the foil thickness was reduced to 100 mm using a two-bus rolling method.
μ-rolled, washed with a surfactant, and annealed in a vacuum at 550° C. for 10 hours. The next step is the same as the conventional one, in which the pre-roughened and rolled aluminum foil is etched in an etching solution of 6.0 wt% hydrochloric acid at 82°C at a current density of 1101 A/cm and an electrical quantity of 2001 A. −
The first roughening treatment is carried out using a DC power supply of in/cj.
In an etching solution of 4.5 wt% hydrochloric acid at 86°C, current density 85 mA/C-', electricity amount 700-A・-in/
A second surface roughening treatment is performed using a DC power supply of cl, and the liquid 1i85
Dechlorination treatment is performed for 1 minute with a 3 wt % boric acid solution at °C. Then, as a pretreatment for anodic oxidation, boiled in pure water for 10 minutes, and prepared Liquid I! 85℃ boric acid 8vt%, boron 0.1211Tt
% chemical solution at 350V for 30 minutes and anodized.

Example 1, which is the anode foil according to the present invention obtained in this way, and the raw aluminum foil with a thickness of 100μ were subjected to a first roughening treatment under the same conditions as described above, and a second roughening treatment. Table 1 shows a comparison with Conventional Example 1, which is an anode foil obtained by processing, dechlorinating, and anodizing.

Comparison of Mini L Actual 1 and Example 1 Compared to conventional example 1, example 1 according to the present invention can improve the capacitance value without causing a decrease in bending strength and tensile strength. .

[Example 2] A raw aluminum foil having a foil thickness of 400 μm is washed with a surfactant and annealed in a vacuum state at 550° C. for 6 hours. next,
In an etching solution containing 6.0 wt% hydrochloric acid at a liquid temperature of 90°C, the current density was 1001 A/cm', and the amount of electricity was 200-A・1.
Preliminary surface roughening treatment is performed using a DC power source of n/cd. After drying, the liquid crystal was dechlorinated for 1 minute using a 3 wt % boric acid solution at 85°C. Subsequently, the foil thickness was reduced to 70 mm using a 3-bath rolling method.
μ-rolled, washed with a surfactant, and annealed in a vacuum at 450° C. for 6 hours. The next step is similar to the conventional one, in which the pre-roughened and rolled aluminum foil is mixed with a solution of 8.0 wt% hydrochloric acid at 46°C and 0.01 sulfuric acid.
In an etching solution containing 0.9111 t% of phosphoric acid and 0.5 wt% of nitric acid, an alternating current (7.5 Hz) with a current density of 8001 A/cm and an amount of electricity of 1900
> A first surface roughening treatment is performed using a power source, and a dechlorination treatment is performed for 40 seconds using a solution containing 2 wt % phosphoric acid at 50°C. And liquid I! 80℃ phosphoric acid 0.1wt%, ammonia 0.1
The product was chemically converted at 100V for 30 minutes in a 5wt% chemical solution and anodized.

Example 2, which is the anode foil according to the present invention thus obtained, and the raw aluminum foil with a foil thickness of 70 μm were subjected to a first roughening treatment and a dechlorination treatment under the same conditions as described above. Table 2 shows a comparison with Conventional Example 2, which is an anode foil obtained by anodizing.

tW Comparison of Example 2 and Conventional Example 2 According to Example 2 according to the present invention, the bending strength and tensile strength are equivalent to those of Conventional Example 2, and the capacitance value can be improved compared to Conventional Example 2. .

[Example 3] A raw aluminum foil with a foil thickness of 400 μm is washed with a surfactant and annealed in a vacuum state at 350° C. for 6 hours. next,
Current density 500 mA/cw' in salt @ 10.0 wt% etching solution with liquid temperature 65°C, N amount 4501
Preliminary surface roughening treatment is performed using an AC (50) 1z) power source of A.1n/cgf. After that, add 13 w of liquid water at 85°C.
Dechlorination treatment is performed for 1 minute with a t% solution. Subsequently, the foil is rolled to a thickness of 90 μm using a three-bus rolling means. In this case, cleaning and annealing are not performed. The next step is the same as the conventional one, in which the pre-roughened and rolled aluminum foil is soaked in 2vt% hydrochloric acid at a liquid temperature of 92°C.

Current density 70 in etching solution of 2wt% sodium sulfate
01A/CI', electricity amount 800+eA -giin/
cII! The first roughening treatment is performed using a DC power supply of
Dechlorination treatment is carried out for 40 seconds in a solution containing 112 wt% phosphorus at 50"C. Then, the anode according to the present invention obtained in this way is Example 3, which is a foil, and a conventional example, which is an anode foil obtained by subjecting raw aluminum foil with a foil thickness of 90 μm to the 11th surface roughening treatment, dechlorination treatment, and anodization under the same conditions as described above. A comparison with No. 3 is shown in Table 3.

Comparison of tW Example 3 and Conventional Example 3 According to Example 3 according to the present invention, the bending strength and tensile strength are equivalent to those of Conventional Example 3, and the capacitance value can be improved compared to Conventional Example 3.

As described above, a method of manufacturing an aluminum electrode foil is provided by subjecting raw aluminum foil to preliminary roughening treatment and then rolling treatment to a desired foil thickness, and according to the method according to the present invention. The surface area expansion rate of the foil can be improved compared to conventional methods. Although only the case where the preliminary surface roughening treatment is performed using an electrochemical method has been described here, the preliminary surface roughening treatment can also be performed by mechanically creating scratches or the like. It goes without saying that the aluminum electrode foil can also be applied to an anode foil and a cathode foil.

Patent applicant: Elna Co., Ltd.

Claims (1)

[Scope of Claims] (1) A method for producing aluminum electrode foil, which comprises subjecting raw aluminum foil to preliminary surface roughening treatment and then rolling treatment to a desired foil thickness. (2. In claim (1), there is a method for producing an aluminum electrode foil by roughly roughening an aluminum electrode foil that has been pre-roughened and rolled. (3) In claim (1) A method for producing an aluminum electrode foil, which comprises roughly roughening and anodizing an aluminum electrode foil that has been pre-roughened and rolled.