JP2833383B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor.

[0002]

2. Description of the Related Art A solid electrolytic capacitor made of, for example, tantalum is manufactured as follows using a sintered body obtained by molding a fine powder of, for example, tantalum into a predetermined shape and sintering it. That is, the sintered body is electrolytically oxidized to form an oxide film. Next, a semiconductor layer such as a manganese dioxide layer is formed. After forming the semiconductor layer, a carbon paste containing graphite carbon and a resin such as an epoxy resin as main components is applied, heat-treated, and cured to form a carbon layer. This heat treatment is performed to evaporate the solvent in the carbon paste and further promote the polymerization of the resin, and is usually performed at a temperature lower than the thermal decomposition temperature of the resin. After forming the carbon layer, a conductive paste is applied to form a conductive metal layer.

[0003]

However, the resin in the carbon paste wraps around the graphite carbon after curing, so that the contact resistance between the graphite carbons and between the carbon layer and the conductive metal layer seems to be high. Therefore, the conventional solid electrolytic capacitor has a drawback that the equivalent series resistance (hereinafter abbreviated as ESR) in a high frequency region is particularly high.

An object of the present invention is to improve the above-mentioned drawbacks,
An object of the present invention is to provide a method of manufacturing a solid electrolytic capacitor capable of reducing SR and improving high-frequency characteristics.

[0005]

According to the present invention, in order to achieve the above object, an oxide film and a semiconductor layer are sequentially formed on a valve metal, and then a carbon paste containing graphite carbon and a resin as main components is formed. Provided is a method for manufacturing a solid electrolytic capacitor in which a carbon layer is formed by applying and heating, wherein a heat treatment is performed at a temperature equal to or higher than a thermal decomposition temperature of a resin after applying a carbon paste. Things.

[0006]

When the carbon paste is applied and then heat-treated at a temperature not lower than the thermal decomposition temperature of the resin in the paste, the resin is polymerized, and a part of the resin enclosing the graphite carbon is thermally decomposed. Therefore, the contact resistance between the graphite carbon and the carbon layer and the conductive metal layer is reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
First, tantalum fine powder is pressure-formed into a square or cylindrical shape. At this time, one end of the tantalum lead wire is put into the fine powder, and the other end is pulled out. Then, after molding, sintering is performed to form a sintered body. Next, this sintered body is immersed in an electrolytic solution such as nitric acid or phosphoric acid and formed to form an oxide film. After forming the oxide film, the sintered body is immersed in a manganese nitrate solution to be impregnated with the solution, and then fired and re-formed. These processes are repeated several times to form a manganese dioxide layer having a predetermined thickness. After forming the manganese dioxide layer, a carbon paste is applied. The carbon paste is a solution obtained by mixing graphite carbon and epoxy resin at a ratio of 59%: 41%, respectively, as a stock solution, and this stock solution is dissolved at a ratio of 1: 1 in a solvent composed of butyl acetate. In addition, an acrylic resin or carboxymethyl cellulose may be used as the resin. Then, after applying the carbon paste, it is left in an atmosphere at a temperature of 20 to 30 ° C. and a humidity of about 60% for 30 minutes. After standing, the thermal decomposition temperature of the epoxy resin (285
Heat treatment at 300 ° C. or higher for 60 minutes. Thereby, a carbon layer is formed. After forming the carbon layer,
A conductive paste mainly containing a resin such as silver and an epoxy resin is applied, and a heat treatment is performed at a temperature equal to or lower than a thermal decomposition temperature of the resin to form a conductive metal layer. After forming the conductive metal layer, the anode terminal and the cathode terminal are connected, and an exterior is formed by a resin mold or the like.

Next, with respect to a tantalum solid electrolytic capacitor having a rated voltage of 10 V and 47 μF, ESR was measured for Examples and Conventional Examples in which the heating temperature when forming the carbon layer was variously changed. The measurement of ESR is performed at f = 100 Kz. The results were as shown in Table 1.

[0009]

As is clear from Table 1, according to the embodiment, E
SR becomes 0.18Ω, as compared with Conventional Examples 1 to 3.
It drops to about 36% to 51%.

[0011]

As described above, according to the production method of the present invention, since the carbon paste is applied and then heated at a temperature not lower than the thermal decomposition temperature of the resin of the component, the contact resistance between the graphite carbons is reduced. A solid electrolytic capacitor that can be reduced, has a small ESR and can improve high-frequency characteristics can be obtained.

Claims (1)

(57) [Claims] 1. A method of manufacturing a solid electrolytic capacitor in which an oxide film and a semiconductor layer are sequentially formed on a valve metal, and a carbon paste containing graphite carbon and a resin as main components is applied and heat-treated to form a carbon layer. At
A method for producing a solid electrolytic capacitor, which comprises subjecting a carbon paste to a heat treatment at a temperature equal to or higher than a thermal decomposition temperature of a resin after application.