JPS6015141B2 - Manufacturing method of solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a solid electrolytic capacitor.

In general, solid electrolytic capacitors are produced by forming a dielectric oxide film on the surface of a valve-acting metal such as tantalum, aluminum, or titanium, which is then soaked in a metal salt solution such as nitric acid and thermally decomposed to produce a semiconductor such as manganese dioxide. It is manufactured by depositing a metal oxide with chemical properties and then forming a carbon layer and a metal layer.

That is, it is necessary to thermally decompose the metal salt to coat the semiconductor layer on the dielectric oxide film.

For example, in the case of tantalum solid electrolytic capacitors, a manganese dioxide layer is formed on a tantalum sintered body, but for this purpose, the sintered body is immersed in manganese nitrate, the manganese nitrate is soaked, and then heated at a high temperature (200 to 300 oo). The decomposition process must be repeated several times to several times. Therefore, during the capacitor manufacturing process, a lot of time is required for this soaking and thermal decomposition, and it has been desired to simplify the process. Furthermore, due to repeated thermal decomposition at high temperatures, the tantalum oxide film deteriorates, resulting in deterioration of characteristics such as leakage current. An object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor that can improve the above-mentioned drawbacks, facilitate manufacturing, and improve characteristics such as leakage current.

In order to achieve the above object, the present invention generates a dielectric oxide film on a metal having a valve action, and then impregnates a manganese nitrate aqueous solution and thermally decomposes it to form a manganese dioxide layer, and forms a carbon layer and a conductive layer. The present invention provides a method for manufacturing a solid electrolytic capacitor, which comprises thermally decomposing a manganese nitrate aqueous solution to which an adsorbent consisting of Ni○-Si02 is added.

In the present invention, when thermally decomposing a manganese nitrate aqueous solution,
Due to the presence of the -S;02 adsorbent, nitrogen oxides that are normally generated during thermal decomposition of an aqueous manganese nitrate solution are adsorbed to this adsorbent, promoting the thermal decomposition reaction and shortening the production time. ) Also, the temperature during thermal decomposition is 30~
Since it can be lowered to about 5,000, deterioration of the dielectric oxide film is also reduced and characteristics such as leakage current are improved.

Hereinafter, the present invention will be explained based on examples.

First, tantalum powder is formed, phosphorized, and chemically converted. After chemical formation, the sintered body is immersed in an aqueous manganese nitrate solution to impregnate it with the liquid. Ni○-Si02 is added to the manganese nitrate aqueous solution as an adsorbent. After impregnating with the liquid, the Akatsuki compact is fired to form a manganese dioxide layer. After firing, processes such as reconversion treatment, carbon coating, and silver paste coating are performed to form a capacitor. Various characteristics were compared between the examples manufactured by the method of the present invention described above and those manufactured by the conventional method.

The composition and thermal decomposition conditions of the manganese nitrate aqueous solution are shown in Table 1, and the characteristic results shown in Table 2 were obtained. That is,
Regarding loss and leakage current, both the initial characteristics and the characteristics after being left unused are smaller in the present invention than in the conventional example, and the capacitance change rate after being left unused is also 4.
Both have improved characteristics. Furthermore, the thermal decomposition time can be reduced to about 60% of the conventional time, and the manufacturing time is shortened.
Table 1 Table 2 As described above, according to the present invention, the time required for thermal decomposition can be shortened, which simplifies manufacturing, and the thermal decomposition temperature can also be reduced, suppressing deterioration of the dielectric oxide film and improving solid electrolysis. Capacitor characteristics can be improved.

Claims (1)

[Claims] 1. A method for manufacturing a solid electrolytic capacitor, in which a dielectric oxide film is formed on a metal having a valve action, and then a manganese dioxide layer is provided by impregnating a manganese nitrate aqueous solution and thermally decomposed, and a carbon layer and a conductive layer are sequentially formed, Ni
A method for producing a solid electrolytic capacitor, which comprises thermally decomposing a manganese nitrate aqueous solution to which an adsorbent consisting of O-SiO_2 is added.