JPH097901A - Solid electrolytic capacitor and its manufacturing method - Google Patents

Abstract

PURPOSE: To prevent a position deviation of a lead terminal and a leakage current by a method wherein an opening end part of a casing is hermetically sealed by a sealing member made of rubber and the lead terminal of a capacitor element is led out from its through hole and an epoxy resin layer is formed on the upper face of the sealing member and a top end part of the lead terminal is bent for surface mounting. CONSTITUTION: Lead terminals 51, 52 of a capacitor element 7 are inserted and penetrated into a hole of a casing sealing member 10 made of rubber and the sealing member 10 is mounted and fixed to lead boss parts 61, 62 in a root portion of the lead terminals 51, 52. The capacitor element having the sealing member is received in a casing 92 and a side face near an opening part of the casing is curled to fasten the sealing member 10, whereby the opening part of the casing is hermetically sealed. Thereafter, an epoxy resin layer 11 is formed on an upper face of the sealing member. Further, when making it as a vertical chip for surface mounting, the lead terminals 51, 52 are inserted into a hole of a base made of plastic and penetrated and bent and a capacitor body is fixed to the base.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A solid electrolytic capacitor using a TCNQ complex salt, which is a type of organic semiconductor, as an electrolyte is disclosed in Japanese Patent Publication No.
It is disclosed in Japanese Patent Publication No. 52939. Where TCN
Q means 7,7,8,8-tetracyanoquinodimethane.

Conventionally, such a solid electrolytic capacitor has been manufactured through the following steps.

That is, first, as shown in FIG. 5, a surface of an etched aluminum foil 1 for an anode is subjected to a chemical conversion treatment to form a dielectric film, and the anode foil 1 is connected to a cathode foil 2 and a separator.
The capacitor element 7 is formed by winding together with the paper 3. In FIG. 5, 4 is a winding tape, 51 and 52 are lead terminals for the anode and the cathode, and 61 and 62 are lead bosses that form the roots of the lead terminals. On the other hand, TCNQ
An appropriate amount of complex salt powder is packed in a cylindrical aluminum case having a bottom, and this is heated to melt and liquefy the TCNQ complex salt. Then, the capacitor element is inserted and immersed in the melted and liquefied TCNQ complex salt through the opening of the aluminum case,
The inside of the capacitor element is impregnated with TCNQ complex salt as an electrolyte and immediately cooled to solidify the TCNQ complex salt. Finally, as shown in FIG. 6, the opening of the aluminum case 90 is sealed with an epoxy resin 8.

[0005]

The solid electrolytic capacitor according to the prior art described above has a case in which the opening of the case is sealed with an epoxy resin, so that the temperature characteristics, high temperature load characteristics,
It has excellent moisture resistance, high reliability, and environmental resistance, but it has the following drawbacks.

That is, in the process of immersing the capacitor element in the melted and liquefied TCNQ complex salt and then cooling and solidifying the TCNQ complex salt, the capacitor element is formed into an aluminum case.
The position of the lead terminal at the opening of the case may shift due to movement within the space.

The above-mentioned problems not only lead to dimensional defects as a product as they are, but especially when processing such as molding of lead terminals after curing of epoxy resin for surface mounting is carried out. It is necessary to design the dimensions so that the dimensional error can be relatively absorbed, and the size becomes large for surface mounting, and the cost of the product also increases.

On the other hand, if the rubber sealing method commonly used in electrolytic solution type capacitors is simply used as the sealing method for the solid electrolytic capacitor, the following problems occur.

That is, when the TCNQ complex salt is impregnated after the sealing rubber is attached to the lead terminals of the capacitor element, there is a risk that the rubber expands and deteriorates due to the heating in the impregnation step and does not enter the aluminum case. In order to avoid the problem, rubber with excellent heat resistance is required, resulting in high cost.

Further, when the sealing rubber is mounted after the capacitor element is impregnated with the TCNQ complex salt, the rubber must be inserted from the opening of the aluminum case and the lead terminal of the capacitor element must be penetrated through the rubber. As a result, not only is workability poor, but defective appearance occurs due to incomplete mounting.

Further, when the solid electrolytic capacitor having the rubber seal is placed on a plastic seat plate and the like, and the lead terminal is bent to be a chip component for surface mounting, a machine for bending the lead terminal is used. Stress is transmitted to the lead boss and electrode foil, and also to the solid electrolyte around it, causing cracks in the joint between the lead terminal and electrode foil and in the solid electrolyte, damaging the dielectric film of the electrode foil and causing leakage current failure. Occurs.

The present invention solves the above-mentioned problems associated with solid electrolytic capacitors.

[0013]

A solid electrolytic capacitor according to the present invention has a TCNQ melted and liquefied in a first case.
A wound type capacitor element is inserted and immersed in an electrolyte material such as a complex salt to impregnate the inside of the capacitor element with the electrolyte material, and the capacitor element is pulled out from the first case and the capacitor element is also removed. The electrolyte material inside is cooled and solidified, a rubber case-sealing member is attached to the root portion of the lead terminal of the capacitor element, and the capacitor element with the sealing member is housed in the second case. The opening end of the second case is sealed with the sealing member, an epoxy resin layer is formed on the upper surface of the sealing member, and the tip end of the lead terminal is bent and formed into a shape for surface mounting.

[0014]

According to the present invention, after the capacitor element impregnated with the electrolyte material is pulled out from the first case, a rubber case sealing member is attached to the root portion of the lead terminal of the capacitor element. By accommodating the capacitor element with the sealing member in the second case, various problems caused by the positional deviation of the lead terminals can be solved.

Further, the epoxy resin layer formed on the upper surface of the rubber sealing member reinforces the root portion of the lead terminal to absorb mechanical stress when the lead terminal is bent and damages the capacitor element due to the stress. And the occurrence of leakage current defects are suppressed.

[0016]

Embodiments of the present invention will be described below.

In the method of manufacturing a solid electrolytic capacitor according to the embodiment of the present invention, first, as shown in FIG. 5, the surface of the etched aluminum foil 1 for anode is subjected to chemical conversion treatment to form a dielectric film, and the anode foil is formed. 1 is wound together with the cathode foil 2 and the separator paper 3 to form the capacitor element 7. On the other hand, an appropriate amount of TCNQ complex salt powder is packed in a cylindrical first aluminum case having a bottom, and this is heated to melt and liquefy the TCNQ complex salt.

Then, as shown in FIG. 2, the capacitor element 7 is inserted and immersed in the melted and liquefied TCNQ complex salt through the opening of the first aluminum case 91, and the TCNQ complex salt as an electrolyte is placed inside the capacitor element. Immediately after the impregnation with, the capacitor element is immediately pulled out from the first aluminum case, and the TCNQ complex salt is cooled and solidified.

Thereafter, as shown in FIG. 1, the lead terminals 51 and 52 of the capacitor element 7 are inserted and penetrated into the holes of the rubber case sealing member 10, and the sealing member 10 is connected to the lead terminals 51 and 52. Lead boss 6 at the root of 52
1 and 62, the capacitor element with a sealing member is housed in the second aluminum case 92 for a finished product, and the side surface near the opening of the second aluminum case is curled. After the opening of the case is sealed by tightening the sealing member 10, an epoxy resin in a softened state is injected into the upper surface of the sealing member and cured by heating to form the epoxy resin layer 11.

Further, in the case of the vertical chip type for surface mounting, as shown in FIG. 3, the lead terminals 51 and 52 are inserted into the holes of the plastic pedestal 12, penetrated, and bent. Fix the capacitor body to the pedestal.

Further, in the case of the horizontal chip type, as shown in FIG. 4, the lead terminals 51 and 52 are bent and formed into a predetermined shape, and then the capacitor body is formed into a cavity of the exterior plastic case 13. Store and fix in the section.

[0022]

According to the present invention, after the capacitor element impregnated with the electrolyte material is pulled out from the first case, a rubber case sealing member is attached to the root portion of the lead terminal of the capacitor element. And then the capacitor element with the sealing member second
By accommodating in the case of 1, the various problems caused by the displacement of the lead terminals are solved, and a small solid electrolytic capacitor suitable for surface mounting or the like is provided.

Further, by forming an epoxy resin layer on the upper surface of the rubber sealing member, the capacitor element is protected from mechanical stress when the lead terminals are bent, and as shown in Table 1, generation of leakage current defects is suppressed. It

[0024]

[Table 1]

Table 1 shows Example 1 in which a TCNQ complex salt was used as an electrolyte, a solid electrolytic capacitor having a rated voltage of 16 V and a rated capacity of 3.3 μF was used in combination with rubber sealing and epoxy resin layer formation, and TCNQ complex salt was used as an electrolyte. Rated voltage 1
Comparative example 1 with a solid electrolytic capacitor of 6 V and a rated capacity of 3.3 μF using only a rubber sealing, and a solid electrolytic capacitor with a rated voltage of 10 V and a rated capacity of 10 μF using TCNQ complex salt as an electrolyte were combined with rubber sealing and epoxy resin layer formation. For each of 100 samples of Example 2 and Comparative Example 2 using a TCNQ complex salt as an electrolyte, a solid electrolytic capacitor having a rated voltage of 10 V and a rated capacity of 10 μF and only a rubber seal,
The state of occurrence of leakage current failure (LC failure) after molding the lead terminals was examined.

In Comparative Examples 1 and 2 using only the rubber seal, defective leakage current occurred, but in Examples 1 and 2 in which the rubber seal and epoxy resin layer formation were used together, there was no leakage current defect. ing.

Further, the combined use of the rubber sealing and the epoxy resin layer formation also contributes to the improvement of moisture resistance as shown in Table 2.

[0028]

[Table 2]

Table 2 shows 50 samples of each of Example 2 and Comparative Example 2 under the environment of a temperature of 60 ° C. and a humidity of 90%.
The humidity resistance test was performed for 000 hours, and the change in capacitance (ΔC / C) before and after the test was examined.

In Example 2 in which rubber sealing and epoxy resin layer formation were used together, the change in capacitance due to the humidity resistance test was smaller than in Comparative Example 2 in which only rubber sealing was performed.

[Brief description of drawings]

FIG. 1 is a sectional view of a solid electrolytic capacitor according to an embodiment of the present invention before bending a lead terminal.

FIG. 2 is a cross-sectional view for explaining an electrolyte impregnation step in the example of the present invention.

FIG. 3 is a partially exploded perspective view of a capacitor element.

FIG. 4 is a side view of a vertical chip type capacitor.

FIG. 5 is a perspective view of a horizontal chip type capacitor.

FIG. 6 is a cross-sectional view of a conventional solid electrolytic capacitor.

[Explanation of symbols]

 51, 52 Lead terminals 61, 62 Lead boss 7 Capacitor element 91 First case 92 Second case 10 Rubber sealing member 11 Epoxy resin layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidemi Fuchigami, Inami, 217 Fukumo, Omachi-machi, Kishima-gun, Saga Prefecture, inside Saga Sanyo Kogyo Co., Ltd. No. 5-5 Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A solid electrolytic capacitor in which a spirally wound capacitor element is impregnated with a solid electrolyte, and the capacitor element is housed in a cylindrical case having a bottom, wherein an opening end of the case is made of rubber. The lead terminal of the capacitor element is pulled out from the through hole provided in the sealing member while being sealed by a member, an epoxy resin layer is formed on the upper surface of the sealing member, and the tip portion of the lead terminal is for surface mounting. A solid electrolytic capacitor, which is formed by bending into the shape of. 2. The solid electrolytic capacitor according to claim 1, wherein the electrolyte impregnated in the capacitor element is a TCNQ complex salt. 3. A step of impregnating the electrolytic material into the inside of the capacitor element by inserting and immersing the wound type capacitor element in the molten and liquefied electrolytic material in the first case, and the capacitor element. Removing from the first case and cooling and solidifying the electrolyte material inside the capacitor element; mounting a rubber case sealing member at the root of the lead terminal of the capacitor element; A step of housing the capacitor element with a sealing member in a second case and sealing the opening end of the second case with the sealing member, and a step of forming an epoxy resin layer on the upper surface of the sealing member. And a step of bending and forming the tip portion of the lead terminal into a shape for surface mounting.