JP3147387B2 - Method for manufacturing anode body for 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 of manufacturing an anode for a solid electrolytic capacitor, and more particularly to a method of forming a valve metal powder compact.

[0002]

2. Description of the Related Art As shown in FIG. 3, an anode body used in a conventional solid electrolytic capacitor is, for example, tantalum, niobium, or the like.
The valve action metal powder is granulated by mixing and preparing a valve action metal powder such as titanium and the organic binder 4,
An anode lead was erected on the thus obtained molded body of the valve action metal powder and sintered at a high temperature and a high vacuum to obtain the anode body 1.

[0003]

In this conventional method for manufacturing an anode body for a solid electrolytic capacitor, granulation is carried out by mixing a binder in order to increase the fluidity of the valve metal powder. When the solid electrolyte capacitor is used as a solid electrolytic capacitor, the pore diameter of the anode body becomes smaller due to the breakdown voltage of the anode body and the anode body is crushed, the impregnation of manganese nitrate when the solid electrolyte layer is formed is poor, and the solid electrolyte layer (Hereinafter referred to as "covering rate"), there is a problem that a capacity failure and a dielectric loss tangent in a solid electrolytic capacitor occur.

[0004] In addition, it is difficult to uniformly granulate the conventional binder mixture, the particle size distribution after granulation is not uniform, and the density variation of the compact is large. For this reason, the strength of the molded body was weak, and the appearance defect such as cracking and chipping of the anode body often occurred.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate poor pressure resistance of a solid electrolytic capacitor due to a binder impurity mixed with a valve metal, improve coverage of a solid electrolyte, and prevent defective capacity and dielectric loss tangent. Another object of the present invention is to provide a method of manufacturing an anode body for a solid electrolytic capacitor, which can reduce poor molded article strength, cracks in the anode body, and poor appearance of chips.

[0006]

SUMMARY OF THE INVENTION A method of manufacturing an anode body for a solid electrolytic capacitor according to the present invention comprises the steps of compressing and forming a valve metal and implanting an anode lead to form a formed body; In the method for producing an anode body for a solid electrolytic capacitor having a step of sintering in a high temperature and high vacuum, the valve body is formed by compressing and molding a valve action metal powder granulated by heat treatment without using the binder. To form , and
The valve action metal powder granulated by the heat treatment should be 50 mesh or less.
It is characterized in that it is used with a particle size of 400 mesh or lower .

[0007]

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an anode body formed by the method for manufacturing an anode body for a solid electrolytic capacitor of the present invention.

First, K2 TaF7 is melted together with a suitable diluting salt and reacted with Na, or a single particle of 2 to 10 μm tantalum powder is obtained by means of absorbing hydrogen into a Ta ingot, embrittlement and mechanical pulverization. And then 1
20 to 15 by heat treatment at 200 to 1500 ° C.
It is a granulated powder of 0 μm.

The tantalum valve action metal powder 3 thus obtained is sieved to a fine powder region 3b of 400 mesh or less.
Is removed. Next, a part of the anode lead 2 is buried in the metal powder 3 after sieving and compression-molded, and further heated as a compact in a high temperature and high vacuum to form the anode body 1 and then a known solid electrolytic capacitor. When a cathode layer such as an oxide film layer, a solid electrolyte layer, a graphite layer, and a silver paste layer is sequentially formed according to the manufacturing method, the pore distribution of the anode body 1 becomes uniform as compared with the prior art, resulting in a large coverage. To improve.

Further, since no binder is mixed,
Compared to the anode body in the prior art, the oxygen,
The impurity contents of both carbon and hydrogen are reduced to 1/10 or less. Therefore, the withstand voltage of the solid electrolytic capacitor is 20
% Or more, and higher reliability is promoted.

As a second embodiment, after a granulated powder is obtained by heat treatment as in the first embodiment, the fine powder region 3b and the coarse powder region 3a of the valve action metal powder 3 are each 400 mesh and 50 mesh. By removing with a mesh sieve,
Further, a metal powder 3 having a uniform particle size distribution is obtained, and as a result, the pore diameter of the anode body becomes uniform, the coverage is improved, and at the same time the strength of the molded body of the anode body is improved. Can be manufactured.

[0013]

As described above, the anode body for a solid electrolytic capacitor manufactured by the method of the present invention is characterized in that the anode lead is planted on a molded body of valve action metal powder and sintered at high temperature and high vacuum. Without using a binder to form the body,
Since the valve action metal powder granulated by the heat treatment is pressed, the pressure resistance of the capacitor is improved by 20% or more without being affected by impurities contained in the binder. In addition, since the powder surface is not coated with the binder resin, there is no slippage between the press die and the metal powder, and there is no crushing of the anode body surface, so the coverage is greatly improved, reducing capacity failure and dielectric loss tangent failure. It is effective.

When the fine powder region and the coarse powder region are removed by sieving, the fluidity of the powder is improved, the variation in the density of the anode body is small, the strength of the compact is improved, and the appearance defects such as cracks and chips of the anode body are reduced. Is done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an anode body for a solid electrolytic capacitor manufactured by a method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an anode body for a solid electrolytic capacitor manufactured by a method according to another embodiment of the present invention.

FIG. 3 is a sectional view of an anode body for a solid electrolytic capacitor manufactured by a conventional manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode body 2 Anode lead 3 Valve action metal powder 3a Coarse grain 3b Fine grain 4 Binder

Claims (1)

(57) [Claims] 1. An anode lead is formed by compressing and molding a valve metal.
Planting to form a molded body;
Sintering in a high vacuum
In the method for producing an anode body for use, the molded body is granulated by heat treatment without using a binder.
Formed by compressing and molding compressed valve action metal powder.
And the valve action metal powder granulated by the heat treatment
A method for producing an anode body for a solid electrolytic capacitor, wherein the anode body is used with a particle size of 400 mesh or less.