JP2002231579A - Method for manufacturing capacitor element of solid- state electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing cost, size and weight in a method for manufacturing a capacitor element composed of a process of sticking an anode wire 3 on one end surface 2a with a valve operating metal and sintering it into a porous anode body 2, a process of forming a dielectric film 4 on the anode body, a process of forming a solid-state electrolytic layer 5 on the anode body by dipping the anode body in a solid-state electrolytic solution, and a process of forming a cathode film 6 on the anode body. SOLUTION: A process of coating the root part of the anode wire on one end surface 2a of the anode body 2 with water-repellent wax 11 is added before the formation of the solid-state electrolytic layer 5 on the anode body 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a capacitor element using a valve metal powder such as tantalum or niobium for an anode body, and a method of manufacturing the capacitor element. .

[0002]

2. Description of the Related Art A capacitor element used in a solid electrolytic capacitor of this type is manufactured as shown in FIGS.

[0003] First, as shown in FIG. 1, a valve metal powder such as tantalum is coated with a porous chip-type anode body 2.
Then, an anode wire 3 is fixed to one end face 2a of the anode wire 3 so that the anode wire 3 projects from the one end face, and is compacted.

[0004] Next, as shown in FIG.
By dipping in a chemical conversion solution B such as a phosphoric acid aqueous solution placed in a container A and performing an anodic oxidation treatment of applying a direct current to the anode body 2 in this state, as shown in FIG. 2, a dielectric film 4 made of tantalum pentoxide or the like having high insulation properties is formed on the surface of each valve metal powder, and the surface of the base of the anode wire 3 protruding from one end face 2a of the anode body 2 is also formed. Then, a dielectric film 4 'made of tantalum pentoxide having high insulating properties is formed.

Next, when the anodic oxidation treatment for forming the dielectric layers 4 and 4 ′ is completed, a ring body 10 made of a synthetic resin such as a fluororesin is attached to the base of the anode wire 3.
The ring body 10 is the one end face 2 of the dielectric film 4.
a is fitted and attached so as to substantially contact the portion a, and in this state,
As shown in FIG. 4, the anode body 2 is dipped in a solid electrolyte aqueous solution D such as a manganese nitrate aqueous solution placed in a container C up to the end face 2a of the anode body 2, pulled up, and heated and fired. By repeating this a plurality of times (for example, about 10 times), a solid electrolyte layer 5 of manganese dioxide is formed on the surface of the dielectric layer 4 in the anode body 2 as shown in FIG.

As shown in FIG. 6, a cathode film 6 having a graphite film as a base and a metal film such as silver as an upper layer is formed on a portion of the surface of the anode body 2 other than the one end surface 2a. Thereby, the capacitor element 1 is obtained.

Prior to the formation of the solid electrolyte layer 5, a ring body 10 is attached to the base of the anode wire 3.
The anode body 2 is dipped in the solid electrolyte aqueous solution D such as a manganese nitrate aqueous solution up to one end surface 2a of the anode body 2 when the solid electrolyte aqueous solution D By preventing the ring body 10 from swelling up to the portion where the dielectric film is not formed beyond the dielectric film 4 'at the base portion, the ring of the solid electrolyte aqueous solution D soaks the cathode side. This is to reduce the occurrence of defective products in which the solid electrolyte layer 5 directly contacts the anode wire 3 on the anode side and is electrically connected therebetween.

As shown in FIG. 7, the capacitor element 1 is disposed between a pair of left and right lead terminals 7 and 8, and the anode wire 3 of the capacitor element 1 is connected to one anode lead terminal 7. On the other hand, the other cathode lead terminals 8 are electrically connected to the cathode film 6 of the anode body 2 while being sealed by welding or the like, and the whole thereof is sealed with a package body 9 made of synthetic resin. Assembled into a solid electrolytic capacitor of the type.

[0009]

A conventional method of manufacturing a capacitor element is to attach a ring made of a synthetic resin to the root of an anode wire during the manufacture of the capacitor element, so that the electrical connection between the anode and the cathode is reduced. There is a problem that the production cost is increased by the use of the link body 10 by ensuring the electrical insulation.

Further, when the capacitor element 1 is assembled into a solid electrolytic capacitor shown in FIG. 7, the dimension between the tip of the anode lead terminal 7 and one end face 2a of the anode body 2 is set between the above. Therefore, the thickness of the ring body 10 must be added to the total length L of the solid electrolytic capacitor, and the size of the solid electrolytic capacitor must be increased. Also, there is a problem that the weight is increased.

An object of the present invention is to solve these problems.

[0012]

Means for Solving the Problems In order to achieve this technical object, a manufacturing method of the present invention comprises a step of fixing an anode wire to one end face with a valve action metal and sintering the same into a porous anode body. Forming a dielectric film on the anode body, applying a water-repellent wax to the root of the anode wire, and then forming a solid electrolyte layer on the anode body by dipping in a solid electrolyte aqueous solution. And a step of forming a cathode film on the anode body. "

[0013]

After the dielectric film is formed on the anode body,
By applying a water-repellent wax to the root of the anode wire fixed to one end surface of the anode body, when forming a solid electrolyte layer on the anode body, the anode body is converted into a solid electrolyte aqueous solution, When the one end surface is dipped, the water-repellent wax can reliably prevent the solid electrolyte aqueous solution from soaking toward the anode wire.

Therefore, according to the present invention, it is possible to omit attaching a ring made of a synthetic resin to the base of the anode wire as in the prior art, so that the manufacturing cost of the capacitor element can be reduced and the capacitor can be reduced. When assembling the element into the solid electrolytic capacitor shown in FIG. 7, the tip of the anode lead terminal can be brought closer to one end surface of the anode body of the capacitor element by the amount that no ring body is provided between them as in the conventional case. Therefore, the total length of the solid electrolytic capacitor can be shortened and its size and weight can be reduced, and the volume of the anode body can be increased by the amount that does not use a ring body as in the conventional case, so that the capacitor capacity can be increased. is there.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

In FIG. 8, reference numeral 2 denotes a porous anode body formed by compacting a valve metal powder such as tantalum into a chip having a square cross section W and sintering it at a high temperature. An anode wire 3 made of a valve metal such as tantalum is fixed to the one end face 2a so as to protrude from the one end face 2a.

The anode body 2 is dipped in a chemical conversion solution B such as a phosphoric acid aqueous solution placed in a container A in the same manner as the case shown in FIG. 2, and a DC current is applied to the anode body 2 in this state. By performing an anodic oxidation treatment, a dielectric film 4 of tantalum pentoxide having a high insulating property is formed on the surface of each valve metal powder in the anode body 2, and protrudes from one end face 2 a of the anode body 2. A dielectric film 4 'made of tantalum pentoxide having high insulating properties is also formed on the surface of the base of the anode wire 3 to be formed.

Next, the base of the anode wire 3 is brushed with a water-repellent wax 11 and pressed over a roller or the like to which wax has been previously attached, or is sprayed from a nozzle of the wax over the entire circumference of the base. Apply.

Next, as shown in FIG. 9, one end face 2a of the anode body 2 is placed in a solid electrolyte aqueous solution D such as a manganese nitrate aqueous solution placed in a container C, as shown in FIG.
10 is repeated a plurality of times (for example, about 10 times), so that the surface of the dielectric layer 4 in the anode body 2 is formed as shown in FIG.
The solid electrolyte layer 5 of manganese dioxide is formed as shown in FIG.

In forming the solid electrolyte layer 5, when the anode body 2 is dipped into a solid electrolyte aqueous solution D such as a manganese nitrate aqueous solution up to the end face 2a of the anode body 2, the solid electrolyte aqueous solution D The water-repellent wax 11 applied to the base of the anode wire 3 can surely prevent the anode wire 3 from soaking up.

The anode body 2 is thereafter
By forming a cathode film 6 having a graphite film as a base and a metal film such as silver as an upper layer on the surface of the solid electrolyte layer 5, as shown in FIG. 11, a finished product of the capacitor element 1 is completed.

As shown in FIG. 12, the capacitor element 1 is disposed between a pair of left and right lead terminals 7, 8, and the anode wire 3 of the capacitor element 1 is connected to one anode lead terminal 7. (The anode wire 3 is fixed by welding or the like.
Needless to say, the wax 11 applied to the surface of the anode body 2 need not be removed by appropriate means). On the other hand, the other cathode lead terminal 8 is electrically connected to the cathode film 6 of the anode body 2,
These components are entirely sealed with a synthetic resin package 9 to assemble a package-type solid electrolytic capacitor.

In this case, the tip of the anode lead terminal 7 and one end face 2a of the anode body 2 in the capacitor element 1
Between the first end face 2 of the anode body 2 and the end of the anode lead terminal 7 because the ring body does not exist as in the prior art.
Therefore, the total length L of the solid electrolytic capacitor can be reduced, and the size and weight of the solid electrolytic capacitor can be reduced.

Further, since the volume of the anode body 2 can be increased by the amount not using the ring body as in the prior art, the capacity of the capacitor can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an anode body in a capacitor element.

FIG. 2 is a cross-sectional view showing a state where a dielectric film is formed on the anode body.

FIG. 3 is a vertical sectional front view of an anode body on which a dielectric film is formed.

FIG. 4 is a cross-sectional view showing a state where a solid electrolyte layer is formed on the anode body.

FIG. 5 is a vertical sectional front view of an anode body having a solid electrolyte layer formed thereon.

FIG. 6 is a vertical sectional front view of a capacitor element in which a dielectric film, a solid electrolyte layer, and a cathode film are formed on an anode body.

FIG. 7 is a vertical sectional front view of a solid electrolytic capacitor using the capacitor element.

FIG. 8 is a vertical sectional front view showing an anode body on which a dielectric film is formed in the embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a state where a solid electrolyte layer is formed on the anode body.

FIG. 10 is a longitudinal sectional front view showing an anode body on which a solid electrolyte layer is formed.

FIG. 11 is a vertical sectional front view of the capacitor element according to the embodiment of the present invention.

FIG. 12 is a vertical sectional front view of a solid electrolytic capacitor using the capacitor element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode body 2a One end surface of anode body 3 Anode wire 4, 4 'Dielectric film 5 Solid electrolyte layer 6 Cathode film 11 Water-repellent wax

Claims (1)

[Claims] 1. A step of fixing an anode wire to one end face with a valve action metal and sintering it into a porous anode body, a step of forming a dielectric film on the anode body, and a root of the anode wire. A step of applying a water-repellent wax to the anode body, a step of forming a solid electrolyte layer on the anode body by dipping into a solid electrolyte aqueous solution, and a step of forming a cathode film on the anode body. Method for manufacturing a capacitor element in a solid electrolytic capacitor.