JPS6242508A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to 7.7.8.8-tetracyanoquinodimethane (
The present invention relates to a method for manufacturing a solid electrolytic capacitor using a solid electrolyte containing a complex salt (hereinafter abbreviated as TCNQ).

2. Description of the Related Art In recent years, with the digitization of electronic devices, it has been desired to reduce the high frequency impedance of the capacitors used. In addition, electrolytic capacitors have traditionally been used as bypass capacitors by taking advantage of their small size and large capacity, but with the recent development of electronic devices, electrolytic capacitors have also been used as bypass capacitors. Improvements such as time-life stability are desired. Conventionally, plastic film capacitors, mica capacitors, multilayer ceramic capacitors, and the like have been used as high-frequency capacitors. Film capacitors and mica capacitors are large in size, so it is difficult to increase their capacitance, and multilayer ceramic capacitors have drawbacks such as extremely poor temperature characteristics and high price when it comes to large-capacity products. On the other hand, aluminum dry electrolytic capacitors, tantalum solid electrolytic capacitors, etc. use a very thin anodic oxide film as a dielectric to achieve large capacity, but on the other hand, the oxide film is easily damaged. In addition, it is necessary to provide an electrolyte layer between the oxide film and the cathode to repair damage from time to time. For example, in an aluminum electrolytic capacitor, an anode/cathode aluminum foil whose surface area has been increased by etching is wound up with a paper separator in between, and the element is impregnated with a liquid electrolyte. For this reason, disadvantages such as an increase in impedance at high frequencies and low temperatures due to the ionic conductivity of the electrolyte, and a decrease in capacitance over time and an increase in loss due to leakage of the electrolyte occur, making it difficult to use as an industrial capacitor. is restricted. In this sense, aluminum and tanker solid electrolytic capacitors are small, large-capacity capacitors that have improved the drawbacks of the aluminum electrolytic capacitors, but they also have some drawbacks.

In manufacturing these solid electrolytic capacitors, an anode is immersed in an aqueous solution of manganese nitrate and thermally decomposed in a high-temperature furnace at around 350'C to produce a solid electrolyte made of manganese dioxide. In this case, it exhibits far superior frequency characteristics, temperature characteristics, and life characteristics compared to liquid electrolytes, but the anodic oxide film is damaged by thermal decomposition several times at high temperatures, and the resistivity of manganese dioxide is high, resulting in Because it exhibits a typical electrical conduction pattern, its impedance or loss in high-frequency and low-temperature regions remains at a considerably higher value than the above-mentioned film capacitor. Here, in order to improve the drawbacks of these capacitors, it has been proposed to use an organic semiconductor with high conductivity and excellent anodic oxidability as a solid electrolyte. In particular, TCNQ@
Organic semiconductors made of salt can be applied to oxide films by dissolving them in organic solvents or melting them by heating, and can reduce damage to oxide films due to thermal decomposition that occurs when impregnating manganese dioxide. can,
By using this TCNQ salt having metallic conductivity, a capacitor with good high frequency characteristics and large capacity can be produced.

Conventionally used TCNQ salts include the invention of the same applicant (Japanese Patent Publication No. 56-10777) and Niwa Shin-
A complex salt containing cationic quinoline, isoquinoline, and pyridine substituted with an alkyl group at the N-position and two molecules of TCNQ is known from the inventions by et al. It is being Since these salts have a clear melting point when the alkyl group has 3 or more carbon atoms, they are impregnated into the capacitor unit by heating and melting, making it possible to form a uniform solid electrolyte layer on the oxide film. This solid electrolyte-impregnated unit generally uses a thermosetting organic polymer sealing material to impart moisture, heat resistance, impact resistance, etc.
It is packaged by any method such as dipping, casting, or botting, and then put into practical use. In order to achieve the above-mentioned purpose of the exterior, a heat-curable adhesive sealing material based on epoxy resin is often used.

Problems to be Solved by the Invention However, in the case of the exterior using epoxy resin as described above, the oxide film formed on the anode may be damaged due to curing shrinkage, or the uncured epoxy resin and curing agent may be mixed with TCNQ. The electrolyte is affected by interactions such as reaction or dissolution with salt, resulting in problems such as an increase in leakage current and a decrease in capacity. The present invention solves the above-mentioned problems, and aims to provide a method for manufacturing a high-performance solid electrolytic capacitor that has a small capacity drop during packaging and a small leakage current.

Means for Solving the Problems The present invention involves forming a silicone film with rubber-like elasticity on the surface of a capacitor unit impregnated with a solid electrolyte containing a TCNQ complex salt and having an oxide film on the anode metal surface. polyphenylene sulfide (hereinafter referred to as PP)
The above object is achieved by performing integral molding using a molding material containing a resin (abbreviated as S).

Function As described above, the present invention provides a silicone film having rubber-like elasticity on the surface of a capacitor unit made of a solid electrolyte, and integrally molds and covers the capacitor unit with a molding material containing pps resin, which is a thermoplastic resin. In addition to reducing the distortion caused by curing shrinkage that was observed when packaging with curable resin, it also eliminates the interaction between the active uncured resin and the TCNQ complex salt.
Damage to the oxide film on the anode metal surface and the influence on the TCNQ complex salt are suppressed, and a high-performance solid electrolytic capacitor with a large capacity and a small leakage current can be obtained. The silicone film with rubber-like elasticity provided here not only prevents the TCNQ complex salt from coming into direct contact with the molding resin, but also protects the capacitor unit from the pressure force when the pps resin is injected from the cylinder into the mold. It has a protective function. Note that the reason why a molding material containing pps resin is used here is to provide the soldering heat resistance required during capacitor mounting.

Example Examples of the present invention will be described in detail below.

N-n-butylisoquinolinium (TCNQ)2 synthesized by a known method was placed in a mortar, acetone was added to make it into a paste, the mixture was ground until the acetone evaporated and the mixture became dry, and the mixture was heated under reduced pressure at approximately 40°C. The solid electrolyte was dried to completely volatilize the acetone, and then ground to obtain a solid electrolyte for use in impregnating capacitors.

For impregnation, approximately 40 mg of this electrolyte is filled into a 100 AJ cylindrical case, heated and melted at approximately 260'C, and preheated at the same temperature for approximately 20 seconds, and the A/electrolytic capacitor unit is immersed in this melt. This was done by immersion. The capacitor unit used here is approximately 40X
It is a wound type with dimensions of 3 mm, and the Af end face has been chemically treated. After solid electrolyte impregnation, the unit is rapidly cooled down to room temperature.
Junction coating resin KJR8030S (Shin-Etsu Chemical +
! #), using a high-pressure mercury lamp that generates ozone rays,
A film was formed by irradiating ultraviolet rays from a distance of 10 cIn for 20 seconds with a lamp input of 120 W/α. The capacitor unit on which this silicone film is formed is called Susteel LP.
-1 (manufactured by Hodogaya Chemical Industry Co., Ltd.), integral molding was carried out by holding the unit 7 so that it was located approximately at the center. The shape of the exterior product is a cylinder measuring 60 x 6 m, and the molding conditions are as follows.
The injection pressure was 230°C, the resin humidity was 300'C, the mold temperature was 150°C, the injection time was 4 seconds, and the cooling time was 10 seconds.

The mold used was one with a gate size of 1 rxm x 1 g. The characteristics of the solid electrolytic capacitor made in this way are shown in the table. The same table also shows an example of a conventional method in which epoxy resin MEX-19C (manufactured by Asahi Chemical Research Institute) is used as the exterior material, without coating with KT R8030S, and instead of integral molding, 85 For comparison, the properties of a sample prepared in the same manner except that the casting exterior was carried out under the curing conditions of 3 hours at °C are shown.

Table K J If a silicone film with rubber-like elasticity is formed on the surface of the capacitor unit using R8030S and then integrally molded with Sasteel LP-1, the capacitance decrease due to the exterior packaging will be smaller and the leakage current will also be smaller. has been proven.

Note that the silicone used in the above embodiments may be any material as long as it is flexible and has rubber-like elasticity, and is not limited to the curing method of ultraviolet curing, and moisture-curing and catalyst-curing silicones are also included in the present invention. Ru. Further, the molding material only needs to contain polyphenylene sulfide wood in terms of wood quality, and the present invention is not limited to the type, amount, etc. of other additives added to improve properties.

Effects of the Invention As described above, the present invention provides a silicone film having rubber-like elasticity on the surface of a capacitor unit impregnated with a solid electrolyte containing a TCNQ complex salt and having an oxide film on the anode metal surface. It is designed to be integrally molded and packaged with a molding material containing Fido resin, and it is possible to suppress a decrease in capacity during packaging and also to reduce water leakage current.

Claims (1)

[Claims] A capacitor unit having an anode metal having an oxide film on its surface is impregnated with a solid electrolyte containing a complex salt of 7,7,8,8-tetracyanoquinodimethane, and then a silicone film having rubber-like elasticity is applied to the surface of the unit. A method for manufacturing a solid electrolytic capacitor, comprising the step of integrally molding the formed polyphenylene sulfide resin with a molding material.