JPS6014502B2 - Manufacturing method of aluminum solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the manufacturing method of aluminum solid electrolytic capacitors.

Conventionally, the thermal decomposition method of manganese nitrate has been used to manufacture aluminum solid electrolytic capacitors.

In the production of aluminum solid electrolytic capacitors using this method, an oxide film is formed on the surface of the aluminum anode body by chemical conversion treatment, and an aqueous solution of manganese nitrate is deposited thereon, and then nitric acid is heated to 200 qo to 300 qo. Manganese is thermally decomposed to produce manganese dioxide, on which a cathode layer is formed using graphite or the like. The anode body of the aluminum solid electrolytic capacitor formed in this way is made of an aluminum block whose surface is electrochemically etched to increase its effective area, or an aluminum powder coated with aluminum powder. However, the former is generally used in consideration of mass production. In order to improve the frequency characteristics of such an aluminum solid electrolytic capacitor to the same level as a Mylar capacitor or a ceramic capacitor, it is necessary to increase the bit diameter of the anode body. However, when the bit diameter is increased, the bit density decreases and the adhesion of Mn02 used as the cathode layer becomes poor, resulting in a drawback that leakage current increases. The present invention has been devised to improve this drawback. That is, in the present invention, an aluminum anode body is etched to form a bit, then a chemical conversion treatment is performed to form an oxide film, an aqueous solution of manganese nitrate is deposited thereon, and then the manganese nitrate is heated. In the manufacturing method of aluminum solid electrolytic capacitors, which consists of various steps of decomposing a manganese dioxide layer to form a manganese dioxide layer and forming a cathode layer using graphite or the like on top of the decomposition, the anode body etching step uses an etching solution containing hydrochloric acid and sulfuric acid. The method is characterized in that after electrolytic etching is performed with a direct current at room temperature, electrolytic etching is performed with an alternating current while the same solution is heated to 70 qo.

Hereinafter, the method of the present invention will be explained in detail based on the accompanying drawings.

FIGS. 1 and 2 are cross-sectional views of the bit in each step of bit formation according to the method of the present invention.

The method of the present invention begins with an aluminum anode body 1 as shown in FIG.
is electrolytically etched with a direct current using an etching solution containing hydrochloric acid and sulfuric acid at room temperature to form a large-mouth bit 2 having a diameter of 0.1 mm or more. Next, as shown in FIG. 2, the anode body 1 with the large-mouth bit formed thereon was further coated with the etching solution.
The bit 3 having a diameter of 0.01 to 1 Am is shallowly formed by electrolytic etching using alternating current in a heated state. Using the anode body with the bits formed in this way, we performed chemical conversion treatment using conventional methods, formed a manganese dioxide layer, and formed a cathode layer using graphite to create a completed aluminum solid electrolytic capacitor with excellent frequency characteristics using large-sized bits. , and the bit formed in the post-process improves the adhesion of M2, resulting in less leakage current. Next, an example will be given and explained.

Example: A block of 2 x 3 x 7 ribs was made of aluminum with a purity of 99.99%, and this was prepared using an etching solution of 16% HC and 2S04, at a solution temperature of 20 qo and a DC current of 2.
00 coulomb/c pongee trowel After performing normal etching, as a post-process, the same solution was heated to 7,000 ℃ and AC 3~
It was etched at 20 coulombs/me.

This anode body was chemically converted at 140V using a shelf acid chemical liquid, a manganese dioxide layer was formed by thermal decomposition of manganese nitrate, and after re-forming and formation of a cathode layer, the exterior was coated with resin to obtain a finished product. Figure 3 shows the characteristics of this finished product in comparison with the subordinate product.

The figure shows the bit density and bit diameter formed in the post-process on the machine axis, and the frequency characteristic △C/C and leakage current A/C on the vertical axis.
After taking AF, the frequency characteristic △C of this example is determined by curve A.
/C, and curve B shows the leakage current A/AF of this example. Note that the subsidiary products (those only for the process shown in Figure 1) are 0.
The frequency characteristic of a large-diameter bit larger than 10 mm is shown by arrow C, and the leakage fin flow is shown by arrow D. As shown in the figure, if the bit diameter is within the range of 0.01 to IAm, the frequency characteristics and leakage current of this example are better than that of conventional products (with a large diameter of 0.1 French m or more, only for the process shown in Fig. 1). It can be seen that it is superior to the bit-forming one).

As explained above, in the manufacturing method of the aluminum solid electrolytic capacitor of the present invention, the bit formation of the aluminum anode body is first performed by 0.1 mounds.
By forming a shallow bit having a diameter of 0.01 to 1 Am after forming the large-diameter bit described above, it is possible to obtain an aluminum solid electrolytic capacitor with excellent frequency characteristics and low leakage current.

[Brief explanation of the drawing]

Figures 1 and 2 are mechanical diagrams showing the cross section of a bit in the bit forming process according to the present invention, and Figure 3 compares the characteristics of an example of an aluminum solid electrolytic capacitor manufactured by the manufacturing method of the present invention with a conventional product. FIG. 1... Aluminum anode body, 2... Large mouth bit, 3... Bit by post-process etching. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 Etching the aluminum anode body to form pits, then performing chemical conversion treatment to form an oxide film, depositing an aqueous solution of manganese nitrate thereon, and heating to thermally decompose the manganese nitrate to form manganese dioxide. In the manufacturing method of aluminum solid electrolytic capacitors, which consists of various steps of forming a layer and forming a cathode layer using graphite or the like on top of the cathode layer, the etching step of the anode body is performed at room temperature using an etching solution containing hydrochloric acid and sulfuric acid. A method for manufacturing an aluminum solid electrolytic capacitor, which comprises performing electrolytic etching using a direct current, and then electrolytically etching the same solution using an alternating current while heating the solution to 70°C.