JP2727353B2 - Solid electrolytic capacitors - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial application field) The present invention relates to a solid electrolytic capacitor excellent in adhesiveness and workability.

(Prior art) A solid electrolytic capacitor is formed by forming a dielectric layer on an anode body made of a metal having a valve action such as tantalum, aluminum, and niobium, and further forming a semiconductor layer and a cathode layer on the surface thereof, and forming a cathode layer on the anode layer. The cathode lead frame is joined to the cathode lead frame by using a two-component conductive adhesive, and the outer peripheral surface thereof is formed of resin.

(Problems to be Solved by the Invention) However, when the cathode layer and the cathode lead frame are joined using a two-component conductive adhesive, the adhesive strength at high temperature is weak, and the anode body lead is solder-bonded in a later process. There is a disadvantage that the deterioration occurs and the electrical characteristics of the solid capacitor change. Further, the two-component conductive adhesive has a merit that it can be cured at a low temperature, but has a drawback of poor workability.

The present invention has been made in order to solve the above-mentioned drawbacks, and in addition to having excellent adhesiveness, not deteriorating the electrical characteristics due to solder bonding, can be cured at a low temperature and has a long pot life, An object of the present invention is to provide a solid electrolytic capacitor using a good adhesive.

[Constitution of the Invention] (Means for Solving the Problems) The present inventors have conducted intensive studies to achieve the above object, and as a result, low-temperature curing is possible by using an adhesive having a composition described later. It has been found that the present invention has excellent workability such as a long pot life and has no deterioration in electrical characteristics due to high temperature of solder bonding, and has completed the present invention.

That is, the present invention provides a solid electrolytic capacitor in which a dielectric layer, a semiconductor layer, and a cathode layer are sequentially formed on the surface of an anode body made of a metal having a valve action, and is covered with a resin. (A) Epoxy compound (B) Curing agent ( A solid electrolytic capacitor characterized in that a cathode layer and a cathode lead frame are joined by using a conductive adhesive having C) an epoxy resin having a benzophenone-based imide group and (D) a conductive powder as essential components. .

The conductive adhesive used in the present invention includes an epoxy compound, a curing agent, an epoxy resin having a benzophenone-based imide group, and a conductive powder as essential components. Each of these components will be described.

The epoxy compound (A) used in the present invention is industrially produced and can be effectively used in the present invention, for example, the following diepoxides of bisphenols. Epikote 827,828,834,1001,1002,
1007,1009 (Ciel Chemical Co., trade name), DER330,331,33
2,334,335,336,337,660 (manufactured by Dow Chemical Company, trade name), Araldite GY-250,260,280,6071,6084,6097,6
099 (Ciba-Geigy Co., trade name), EPI-REZ510,5101
(Manufactured by JONEDABNEY, trade name), Epicron 810,1000,101
0,3010 (product name, manufactured by Dainippon Ink and Chemicals, Inc.), EP series (product name, manufactured by Asahi Denka Co., Ltd.). Further, the epoxy resin having an average number of epoxy groups of 3 or more, for example, a novolak type,
Epoxy resins are preferred. As these novolak epoxy resins, for example, Araldite EPN1138, 1139,
ECN1273,1280,1299 (manufactured by Ciba-Gaiky), DEN
431,438 (manufactured by Dow Chemical Company, trade name), Epicoat 15
2,154 (Ciel Chemical Co., Ltd., trade name), ERR-0100, ERRB-
0447, ERLB-0488 (manufactured by Union Carbide, trade name) and EOCN series (manufactured by Nippon Kayaku Co., Ltd.). These epoxy compounds having a molecular weight of 500 or more are suitable, and they can be used alone or in combination of two or more. Furthermore, it can be diluted with a monofunctional low viscosity epoxy compound.

The curing agent (B) used in the present invention can be widely used as long as it is used as a usual epoxy resin curing agent. For example, an imidazole compound, a phenol compound, a polyamine compound, an acid anhydride compound and the like can be mentioned, and these can be used alone or in combination of two or more.

As the epoxy resin (C) having a benzophenone-based imide group used in the present invention, any resin having an epoxy group and a benzophenone-based imide group in a molecule may be used, and these can be widely used. For example, the following structures can be used.

It is desirable to mix the epoxy resin having a benzophenone-based imide group so that the epoxy resin has a content of 5 to 80% by weight based on the total amount (A + B + C) of the resin components excluding the conductive powder (D). If the compounding ratio is less than 5% by weight, the adhesive strength is low, and if it exceeds 80% by weight, the reactivity is poor, which is not preferable.

As the (D) conductive powder used in the present invention, silver powder,
Examples thereof include copper powder, nickel powder, and powder having a metal layer on the surface, and these can be used alone or in combination of two or more. These conductive powders preferably have an average particle size of 10 μm or less. Average particle size is 10μm
If the ratio exceeds, high-density filling is not possible, and the paste does not form, and the coating performance is undesirably reduced. The compounding ratio of the above-mentioned (A) epoxy compound (B) curing agent, (C) binder composed of epoxy resin having benzophenone-based imide group and conductive powder is 30/70 to 10/90 by weight ratio. Is desirable. If the amount of the conductive powder is less than 70 parts by weight, sufficient conductivity cannot be obtained, and if it exceeds 90 parts by weight, adhesion and workability are undesirably reduced.

For the conductive adhesive used in the present invention, an organic solvent can be used as needed for adjusting the viscosity. Examples of the organic solvent include dioxane, hexane, cellosolve acetate, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, isophorone and the like, and these can be used alone or in combination of two or more.

The conductive adhesive used in the present invention includes an epoxy compound, a curing agent, an epoxy resin having a benzophenone-based imide group, and a conductive powder, and optionally includes an antifoaming agent, a coupling agent, and other additives. be able to. The method for producing the conductive adhesive is an epoxy compound, a curing agent, a reaction with an epoxy resin having a benzophenone-based imide group, and then a conductive powder is added and mixed well. Then, it can be manufactured by degassing under reduced pressure. The conductive adhesive thus produced is filled in a syringe and discharged using a dispenser.

Next, a method for manufacturing the solid electrolytic capacitor of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of a solid electrolytic capacitor of the present invention. The surface of the anode body 1 made of a metal having a valve action, such as tantalum, aluminum, or niobium, is subjected to anodization by a general method to form a dielectric layer 2. Next, a semiconductor layer 3 is formed on the surface of the dielectric layer 2 with graphite or the like, and carbon or a conductive paste, or metal plating or metal deposition is formed on the surface of the semiconductor layer 3 to form a cathode layer 4. Thereafter, the conductive adhesive 6 manufactured as described above is discharged from the syringe onto the lead frame 5, and the cathode layer 4 and the cathode lead frame are adhesively hardened and joined. Anode body lead 7 leading to anode body 1
To the anode lead frame with solder 8. And
Cathode layer 4 and cathode lead frame 5 are joined, and the entire body where anode body lead 7 and solder 8 are joined is molded by a phenol resin or epoxy resin molding method or a dipping method of dipping in phenol resin. The whole was sealed with a resin and the outer cover 9 was manufactured to produce a solid electrolytic capacitor.

(Examples) Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, “parts” means “parts by weight” unless otherwise specified.

Example 1 7.6 parts of epoxy resin EP4400 (trade name, manufactured by Asahi Denka Co., Ltd.)
5.6 parts of p-hydroxystyrene Marcalinker M (trade name, manufactured by Maruzen Petrochemical Co., Ltd.), 0.2 parts of an epoxy resin having a benzophenone-based imide group, 10.4 parts of γ-glycidoxypropyltrimethoxysilane, and 4.0 parts of diethylene glycol diethyl ether, The dissolution reaction was performed at 100 ° C. for 1 hour to obtain a viscous brown resin. In 27.8 parts of this resin,
A conductive adhesive was produced by mixing 0.006 parts of the imidazole compound 2PHZ-CN (trade name, manufactured by Shikoku Chemicals) and 70 parts of silver powder as a catalyst.

Example 2 20.0 parts of epoxy resin Epicoat 828 (trade name, manufactured by Ciel Chemical Co., Ltd.), 0.1 part of an epoxy resin having a benzophenone-based imide group, and 4.0 parts of diethylene glycol diethyl ether were subjected to a dissolution reaction at 100 ° C. for 1 hour to become viscous. A light brown resin was obtained. To 27.8 parts of this resin, 0.006 part of an imidazole compound 2PHZ-CN (described above) as a catalyst and 70 parts of silver powder were mixed to produce a conductive adhesive.

Example 3 Epoxy resin Epicoat 828 (supra) 10.0 parts, EOCN103
10.0 parts of S (trade name, manufactured by Nippon Kayaku Co., Ltd.), 0.1 part of an epoxy resin having a benzophenone-based imide group, and 4.0 parts of butyl cellosolve were subjected to a dissolution reaction at 100 ° C. for 1 hour to obtain a viscous brown resin. To 27.8 parts of this resin, 0.006 part of an imidazole compound 2PHZ-CN (described above) as a catalyst and 70 parts of silver powder were mixed to produce a conductive adhesive.

Comparative Example A commercially available two-component conductive adhesive based on an epoxy resin was obtained.

Using the conductive adhesive obtained in Examples 1 to 3 and Comparative Example, after joining the cathode layer of the solid electrolytic capacitor and the lead frame, the anode body lead was joined by soldering, and then covered with resin to form a solid. An electrolytic capacitor was manufactured. The peel strength and the pot life of the conductive adhesive of the solid electrolytic capacitor thus manufactured were tested, and the results are shown in Table 1.

[Effects of the Invention] As is apparent from the above description and Table 1, the solid electrolytic capacitor of the present invention can be cured at a low temperature because it uses a one-component conductive adhesive having a specific composition, and can be used in a workplace. Excellent in nature. In addition, a highly reliable solid electrolytic capacitor having excellent adhesiveness, particularly excellent adhesiveness at a high temperature, without deterioration of electrical characteristics due to solder bonding can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a solid electrolytic capacitor according to one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Anode body, 2 ... Dielectric layer, 3 ... Semiconductor layer, 4 ... Cathode layer, 5 ... Cathode lead frame, 6 ... Conductive adhesive, 7 ...
Anode lead, 8: solder, 9: exterior resin.

Claims (1)

(57) [Claims] 1. A solid electrolytic capacitor in which a dielectric layer, a semiconductor layer, and a cathode layer are sequentially formed on the surface of an anode body made of a metal having a valve action, and the whole is covered with a resin. (A) Epoxy compound (B) Curing A solid electrolytic capacitor characterized in that a cathode layer and a cathode lead frame are joined by using a conductive adhesive containing (C) an epoxy resin having a benzophenone-based imide group and (D) a conductive powder as essential components. .