JPS59115517A - Method of producing 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] The present invention relates to a method for manufacturing an electrolytic capacitor.

Conventionally, various valve metals such as tantalum, aluminum, niobium, titanium, zirconium, vanadium, and hafnium are known as anode body materials for electrolytic capacitors. These metals form a capacitor using an oxide film formed on the surface as an electric shield. However, for a capacitor to be put into practical use, its characteristics such as leakage current value, withstand voltage, and dielectric loss must reach a certain level or higher.9 Therefore, the only anode body materials currently in practical use are tantalum and aluminum. I'll go. Among these, tantalum has excellent properties, especially low leakage current.
The best anode material for sintered electrolytic capacitors. However, tantalum is a scarce resource and expensive, and
There are problems, including the issue of resource conservation. On the other hand, aluminum has the characteristics of being able to obtain a high operating voltage, being inexpensive, and being an abundant resource, but it also has the problems of high leakage current and difficulty in making small, large-capacity capacitors. I'm in X7. Therefore, in order to compensate for the shortcomings of these tantalum electrolytic capacitors and aluminum electrolytic capacitors, an electrolytic capacitor using an aluminum-titanium alloy as an anode body was developed (Japanese Patent Application No. 14804-1983).
2). Electrolytic capacitors that use an aluminum-titanium alloy as the anode body (hereinafter referred to as aluminum-titanium electrolytic capacitors) use raw materials such as aluminum and titanium, which are significantly cheaper than tantalum, and which have a smaller unit volume MD of the sintered body. Since the surface area is larger than that of an aluminum sintered body, an inexpensive and small electrolytic capacitor can be obtained.

An object of the present invention is to provide a manufacturing method that improves the leakage current value of an aluminum-titanium electrolytic capacitor having these characteristics.

According to the present invention, in the manufacturing process of an electrolytic capacitor in which the anodized film of the anode body made of an alloy metal of aluminum and titanium is used as a current visitor, the anodized film is anodized and then boiled in pure water or in pressurized steam. By including the process of holding the aluminum and titanium in the aluminum alloy, heat treating it, and anodizing it again, the aluminum and titanium alloy oxide film that becomes the dielectric film becomes denser, resulting in a lower leakage current value and less variation in the aluminum alloy. A mu titanium electrolytic capacitor is obtained.

Hereinafter, the present invention will be explained in detail by showing examples.

[Example 1] A porous sintered body made of an alloy of aluminum and titanium having a predetermined composition ratio was anodized at a DC voltage of 100 V in a phosphoric acid aqueous solution of a predetermined concentration. Table 1 shows the combinations of aluminum and titanium composition ratios and phosphoric acid concentrations of each sample. After each sample was anodized, it was subjected to the pure water boiling treatment or pressurized steam treatment of the present invention shown in Table 2. After each treatment, heat treatment was performed at 300° C. for 30 minutes, and then anodization was performed again at a DC voltage of 100 μ in a 0.005 volume phosphoric acid aqueous solution.

Table 3 shows the leakage current values after the second anodic oxidation.

Table 1: The leakage current value is the value 1 minute after applying a rated voltage of 20V in a 0.005 volume phosphoric acid aqueous solution. The leakage current value is measured for the sample, and the center value is k. No significant change in capacitance was observed even after boiling in pure water or holding in pressurized steam, and the capacitance of 1 was 2.5 μF. Figure 1 shows
The leakage current values of a sample subjected to pure water boiling treatment for 30 minutes and a sample subjected to the treatment of the present invention are compared after the second anodic oxidation. Figure 2 shows pressurized steam (2,5
The leakage current values of a sample subjected to 10 minutes of anodic oxidation treatment and a sample not subjected to the first principle of the present invention are compared after the second anodic oxidation.

As seen in Table 3, Figures 1 and 2, leakage current occurs if the process of anodizing is followed by boiling in pure water or holding in pressurized water, heat-treating, and then anodizing again. The value decreases, and its variation also decreases.

Example 2] A manganese dioxide layer was formed on Samples T-1 to T-19 of Example 1 by thermal decomposition of manganese nitrate, and the external cathode was taken out using graphite, Senshi paste and solder, and Sample T'- 1 to Sample T-19 were formed.

3 and 4 show the maximum value, minimum value, and center value of leakage current values measured for 29 samples per level. As shown in FIGS. 3 and 4, samples that have been anodized, boiled in pure water or kept in pressurized steam, heat treated, and then anodized again are treated according to the present invention. Compared to samples that were not subjected to this process, there was less damage to the anodic oxide film during solidification, and the leakage current value after solidification was reduced.

As described above, the present invention has the following effects.

(:) After anodizing a porous sintered body made of an alloy of aluminum and titanium, the process involves boiling it in pure water or holding it in pressurized steam, heat-treating it, and then anodizing it again. Additionally, the leakage current value after anodic oxidation is reduced and its variation is also reduced.

(11) During solidification, the anodic oxide film is less damaged by the thermal decomposition of manganese nitrate, the leakage current value after solidification is reduced, and its variation is also reduced.

[Brief Description of the Drawings] Figures 1 and 2 are comparison diagrams of the leakage current values of the conventional untreated product and the product treated with the present invention after the second anodic oxidation. Boiling treatment, Figure 2 shows a sample subjected to pressurized steam treatment. Figures 3 and 4 are comparison diagrams of the leakage current values of the conventional untreated product and the product treated with the present invention after solidification. This is a processed sample. T-1 to T-5...Conventional untreated product, T-
6 to T-19...Products treated according to the present invention, T-1 to T'
-19... Sample solidified from T-1 to 'l'-19, a... Maximum value, b... Median value,
C: Minimum value.

Claims (1)

[Claims] In the manufacturing process of electrolytic capacitors in which the positive oxidation film of the anode body made of an alloy metal of aluminum and titanium is used as a Kl electrolyte, after being subjected to positive oxidation, the product is boiled in clean water or kept in pressurized steam, A method for manufacturing an electrolytic capacitor, comprising the steps of heat treatment and re-anodizing.