JPS60107819A - Method of producing aluminum electrolytic condenser - 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] (21) Technical Field of the Invention The present invention relates to a method for manufacturing an aluminum solid electrolytic capacitor;
In particular, it relates to a manufacturing method for reducing leakage Ui flow.

(BL Technological Background 74) In an aluminum solid electrolytic capacitor V, an anodized film can be formed to follow the fine irregularities of the anode body. Therefore, the surface of the anode body It is possible to obtain a large capacitance with a small anode body by a surface enlarging process in which the surface area is artificially enlarged by etching, and such a surface enlarging process has already been carried out.

(C) Prior Art and Problems Figure 1 is a partially cutaway front view showing an example of the structure of an aluminum solid electrolyte condenser.

In FIG. 1, a capacitor 1 is constructed by sequentially laminating an anodic oxide film 3 and a manganese dioxide layer 4 on the surface of an anode body 2 to which an anode terminal 7 to which one end of a lead wire 8 is welded is welded. After one end of the cathode lead wire 9 is bonded to the cathode ribbon 5 with solder 10, the resin-covered device 1 is attached.

In such a capacitor 1, the anode body 2 is subjected to heat treatment to remove its internal strain prior to the surface expansion treatment, and the formation of the anodic oxide skin Bm3 has conventionally been performed following the surface expansion treatment. However, the internal strain caused by the surface expansion process was ignored.

(dl Purpose of the Invention The purpose of the present invention is to improve the performance of aluminum solid electrolytic capacitors, and as a result of reviewing the conventional structure and manufacturing method, it has been found that internal strain caused by surface expansion treatment is related to leakage. Since it was found that the internal strain was completely removed, the leakage was prevented.
The goal is to reduce Qf.

tel Structure of the Invention The above object is to subject an anode body made of high-purity aluminum to a surface-expanding treatment, then heat treat it at 280°C to 350°C for 5 to 20 minutes, and then immerse it in a hydrochloric acid-based etching solution to remove the heat treatment. This is achieved by a method for manufacturing an aluminum solid electrolytic capacitor, which is characterized in that the oxide film is dissolved away, and then a varnished film is formed by abrasion. , tfl Implementation of the Invention Hereinafter, this%'! This will be explained using Fig. 2 showing the main safety work 8 of the f4 method.

In No. 2181, the heat treatment step surrounded by two boxes and the etching step following the heat treatment step are steps inserted between the conventional surface enlarging treatment step and the anodic oxide film forming step according to the present invention.

The purpose of the heat treatment step is to remove the internal strain generated by the m1 expansion process, and therefore, the temperature range is higher than the recrystallization start temperature of the anode body (aluminum) and lower than the temperature at which crystal grain biopsy becomes noticeable. i.e. 280℃~35
Heat at 0°C for 5 to 20 minutes. However, the starting temperature for crystallization of aluminum is approximately 150°C, for example, 20°C.
Is it possible to remove the internal strain even if the heat treatment is performed at 0°C?If the treatment temperature is lowered, the treatment time becomes longer and becomes impractical, so in the present invention, the lower limit treatment temperature is set at 280°C.

On the other hand, the etching process for removing the oxide film formed by the heat treatment has conventionally been carried out using @acid 10-20%, sulfuric acid 5-10g/4 aluminum chloride aluminum 1-5 dihydrochloric acid system for surface expansion treatment of the 1tlA pole body. The etching solution 'lc' was used, and I realized that its surface properties were suitable for forming a manganese dioxide layer, so I decided to check it out in the inspection process L84! The same 8-acid-based etching solution was used as in the case. However, the time for immersing the body of the anode after the heat treatment in the etching solution varies depending on the area expansion ratio and the surface texture (from 0 seconds to 40 seconds).

Therefore, we created similar types of capacitors with the configuration shown in Figure 1 using the conventional method and the process of the present invention, which is the process shown in Figure 2, and compared the two. jA:Ireijl'5iL is approximately 100 nA, whereas the capacitor according to the present invention has a more uniform oxide film and fewer defects than the conventional capacitor, and
Its leakage current was 20-30 nA.

According to the invention, the effect of improving the performance by reducing the leakage current of the aluminum IITJ j4s 1: Σ + r capacitor is 45%. The benefits are extremely large.

4. 17 + i 8' r, - Figure 11 is a front view of a partially disassembled aluminum solid Ichida capacitor to show an example of its structure. FIG.

In the figure, 1 is an aluminum solid electrolytic 5R4 capacitor, 2 is an anode body, and 3 is an anodized film.

Claims (1)

[Claims] After surface-expanding the anode body made of high-purity aluminum, it is heat-treated at 280°C to 350°C for 5 to 20 minutes, then immersed in a hydrochloric acid-based etching solution to dissolve away the oxide film, and then the anode A method for manufacturing an aluminum solid electrolytic capacitor, characterized by forming a cylindrical shape (oxidized skin).