JP5890986B2 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

The present invention relates to a solid electrolytic capacitor using a conductive polymer as a solid electrolyte layer and a method for manufacturing the same.

As an electrolytic capacitor mounted on an electronic device, a solid electrolytic capacitor using tantalum, niobium, or the like as a valve metal is used particularly in an electronic device that requires a large capacity. Solid electrolytic capacitors are made by forming a solid electrolyte layer on a porous sintered body made of a valve action metal. Depending on the type of solid electrolyte layer used, manganese dioxide type and conductive polymer or functional polymer type It is divided roughly into what is called.

In recent years, with the improvement in performance of electronic devices, solid electrolytic capacitors have been required to have excellent high frequency characteristics, and the solid electrolyte layer used in the solid electrolytic capacitors has a high conductivity for the purpose of equivalent series resistance (ESR). Molecules are becoming widely used.

Generally, as a conductive polymer used for a solid electrolytic capacitor, there are polythiophene, polypyrrole, polyaniline or derivatives thereof. Among them, polythiophene has higher conductivity than polypyrrole or polyaniline and has excellent thermal stability. Therefore, it is often used as a solid electrolyte.

In the process of forming a conductive polymer, which is a solid electrolyte layer, in a porous sintered body, the device is mainly impregnated with a solution containing appropriately monomers, dopants, oxidizing agents, etc., and chemical polymerization, that is, oxidation polymerization or electrolytic oxidation. There are a method of growing a conductive polymer film on a device by polymerization, and a method of impregnating a device with a conductive polymer dispersion and then drying a dispersion medium of the dispersion.

For example, Patent Document 1 discloses a solid electrolytic capacitor in which a conductive polymer is formed in a capacitor element portion, that is, a porous sintered body by oxidative polymerization to form a solid electrolyte layer, and a method for manufacturing the same.

For example, in Patent Document 2, a conductive polymer solution dispersed in water is impregnated with a porous sintered body of a capacitor element portion, and then the conductive polymer is fixed to the porous sintered body by drying a solvent. A solid electrolytic capacitor for forming a solid electrolyte layer is disclosed.

Further, in Patent Document 3 and Patent Document 4, the conductive polymer solution dispersed in water is impregnated with the porous sintered body of the capacitor element portion, and then the conductive polymer is porous sintered by drying the solvent. A solid electrolytic capacitor in which a solid electrolyte layer is formed by fixing to a body and further performing oxidative polymerization in a solution containing a monomer and a method for manufacturing the same are disclosed.

In Patent Document 5, in order to impart conductivity to the base material without impairing the transparency and mechanical strength of the base material, the conductive polymer and the light are excellent. The technique about the conductive resin-forming composition comprised so that it might consist of a mixture of a curable monomer and an additive is disclosed.

In the method using chemical polymerization, it is difficult to uniformly form a conductive polymer film, and in order to improve it, if a polymerization reaction is further promoted to grow the conductive polymer film thickly, a porous firing is performed. The adhesion of the solid electrolyte layer composed of the aggregate and the conductive polymer tends to deteriorate. As a result, the conductive polymer film is easily peeled off from the solid electrolyte layer, which may cause device failure or performance deterioration. Furthermore, it is often difficult to form a conductive polymer film having high and stable conductivity.

In impregnating the conductive polymer solution dispersed in water with the porous sintered body of the capacitor element portion, and subsequently drying the solvent, the conductive polymer is fixed to the porous sintered body to form a solid electrolyte layer. Since the conductive polymer is synthesized in advance, it can be selected and used with a stable and high conductivity, so that there is no variation in the performance of the capacitor element compared to the case where chemical polymerization is used. However, since the solid electrolyte layer is formed by drying the conductive polymer dispersion, the problem described later in FIG. 6 tends to occur.

FIG. 6A is a cross-sectional view of a conventional capacitor element, particularly a capacitor element 110 in which a conductive polymer dispersion is impregnated with a capacitor element and a solid electrolyte layer is formed by subsequent solvent drying. In this method, in the capacitor element having a rectangular parallelepiped outer shape, the solvent drying at the apex portion becomes faster, or the film thickness of the conductive polymer film at the apex portion of the element is insufficient due to the surface tension of the dispersion liquid, etc. The tendency to do is seen.

FIG. 6B is an enlarged view of the main part Z of FIG. As shown in FIG. 7B, the solid electrolyte layer 1130 is formed for the above-mentioned reason, and the portion where the solid electrolyte layer 1130 is insufficient at the apex portion of the capacitor element, that is, the defect portion X is formed. End up.

FIG. 7A shows a conventional method for manufacturing a solid electrolytic capacitor in which the solid electrolyte layer 1130 is laminated by providing a plurality of impregnation steps in order to improve the above problem. In order to reduce the leakage current value (LC), it is desirable to increase the number of layers and ensure the film thickness.

FIGS. 7B and 7C are enlarged views of the main part Z2 and the main part Z3 in FIG. 7A, respectively. As shown in FIG. 7B, the solid electrolyte layer 113 is laminated, and as shown in FIG. 7C, the defect portion X is covered with the additional solid electrolyte layer 113 that is sequentially laminated.

FIG. 7D shows an impregnation step, that is, the number of laminated films, LC (Leak Current) value, and ESR (Equivalent Series Resistance) value when the capacitor element shown in FIG. It is a graph which shows the relationship. As shown in FIG. 7D, the LC value is reduced by increasing the number of impregnations, but the ESR value is increased conversely, and these two values are not compatible. This is presumed to be caused mainly by the occurrence of interface resistance between the laminated films. Furthermore, during the process of laminating the solid electrolyte layer, as the conductive polymer film is dried and swelled by the solvent, the volume of the film is greatly changed. There is a tendency for the adhesion between the body and the film to deteriorate. This is considered to cause an increase in ESR and device failure.

JP 2003-168631 A JP 2007-335516 A JP 2003-1000056 A1 JP 2009-105171 A JP 2010-202704 A

  In view of the above problems, an object of the present invention is to provide a conductive polymer type solid electrolytic capacitor capable of reducing ESR and reducing element defects, and a method for manufacturing the same.

  A solid electrolytic capacitor according to the present invention includes a porous sintered body made of a valve metal, a dielectric layer covering at least a part of the porous sintered body, and a solid electrolyte covering at least a part of the dielectric layer. A layer. At least a part of the solid electrolyte layer is made of a mixture of a conductive polymer and a photocurable component.

  In a preferred embodiment, the photocurable component is a cationic polymerization type photocurable component.

In a preferred manufacturing method, in the step of forming the solid electrolyte layer, a step of applying a treatment liquid containing a conductive polymer and a photocurable component, a step of removing the excess from the applied treatment liquid, A step of forming a solid electrolyte layer by curing;

In a preferred production method, the treatment liquid contains a conductive polymer, a dopant for adjusting the conductivity of the conductive polymer, a photocurable component, and photocuring of the photocurable component. And a photopolymerization initiator that assists, comprising 20 to 80% by weight of the conductive polymer and 10 to 70% by weight of the photocurable polymerizable liquid.

Further, the treatment liquid contains at least one of an antioxidant that protects the function of the conductive polymer and a surfactant that prevents coating failure.

Furthermore, the treatment liquid may contain an organic solvent for adjusting coating properties.

  In a preferred production method, the photocurable component is a monomer, oligomer or polymer having a photocurable functional group, alone or a mixture thereof, and includes a single liquid compound or a single compound or a plurality of compounds. It is a composition and is a liquid.

  In addition, in a preferable manufacturing method, in the step of forming the solid electrolyte layer by photocuring, a step of applying the treatment liquid to a part or all of the element, and a curing light source on a part of the applied treatment liquid A step of selectively irradiating, and a step of washing away the excess processing liquid not cured in the above step.

  In the method for producing a solid electrolyte membrane made of a conductive polymer disclosed in the present invention, since an organic solvent is not used and a photocurable liquid having a high curing speed and excellent heat resistance is used, A solid charged membrane made of a polymer is not exposed to drying / swelling by a solvent, and therefore there is little volume change at the time of film formation. As a result, the membrane has excellent adhesion to a substrate and is more uniform. A solid electrolyte layer having a film thickness is provided.

  Furthermore, the method for producing a solid electrolytic capacitor of the present invention provides a solid electrolytic film made of a conductive polymer having a uniform film thickness and excellent adhesion, so that a solid electrolytic capacitor with reduced ESR and a low incidence of defects can be obtained. provide. In addition, the solid electrolyte membrane made of a conductive polymer can be controlled to an arbitrary shape and thickness, and can be formed at an arbitrary location, thereby increasing the degree of freedom in designing a solid electrolytic capacitor. .

It is sectional drawing of the solid electrolytic capacitor concerning embodiment of this invention. It is sectional drawing to which the principal part of the solid electrolytic capacitor of this invention was expanded. It is sectional drawing which showed a part of process of forming a solid electrolyte layer in an example of the manufacturing method of the solid electrolytic capacitor concerning embodiment of this invention. It is the conceptual diagram which showed the process of forming a solid electrolyte layer by photocuring reaction in an example of the manufacturing method of the solid electrolytic capacitor concerning embodiment of this invention. It is a conceptual diagram which shows the modification of the manufacturing method of the solid electrolytic capacitor of this invention. FIG. 5A is a cross-sectional view of a capacitor element portion of the solid electrolytic capacitor of the present invention, and FIG. 5B is an enlarged view of a main part thereof. FIG. 6A is a cross-sectional view of a capacitor element portion of a conventional solid electrolytic capacitor, and FIG. 6B is an enlarged view of a main part thereof. FIG. 7A is a cross-sectional view of a capacitor element portion of a conventional solid electrolytic capacitor, and FIGS. 7B and 7C are enlarged views of main parts thereof. FIG. 7D is a conceptual diagram showing the relationship between the number of impregnations and the characteristic value.

<Solid electrolytic capacitor>
The solid electrolytic capacitor of the present invention will be described with reference to FIGS. 1A and 1B.

FIG. 1A shows a solid electrolytic capacitor 100 according to this embodiment. The solid electrolytic capacitor 100 shown in this embodiment has a structure in which a capacitor element 110, a metal strip 120, and an electrode substrate 130 are combined. The capacitor element 110 includes a porous sintered body 111, a dielectric layer 112, and a solid electrolyte layer. 113 and a cathode lead layer 114 are formed in order, and have an anode lead 115. Further, a spread prevention means 116 made of, for example, a fluororesin is attached. The spread prevention means 116 covers a region around the base of the anode lead 115 in the porous sintered body 111 and has a function of preventing the cathode from being short-circuited with the metal strip 120.

The electrode substrate 130 is divided into an anode terminal 130a and a cathode terminal 130b. Further, a conductive adhesive 140 is used at the contact point between the capacitor element 110 and the cathode terminal 130b. Further, the capacitor element 110, the metal strip 120, the entire conductive adhesive 140 and at least a part of the electrode substrate 130 are covered with the sealing resin 150.

FIG. 1B is a conceptual diagram in which a detailed portion of the capacitor element 110 is enlarged. The porous sintered body 111 is made of a valve metal such as tantalum or niobium. The porous sintered body 111 is obtained by pressure-molding the valve action metal fine powder together with the anode lead 115 and subsequently performing a sintering process, and has a structure having a large number of pores 160. .

The dielectric layer 112 is obtained, for example, by subjecting the porous sintered body 111 to an anodic oxidation process in a phosphoric acid aqueous solution. The dielectric layer 112 is formed on the surface of the porous sintered body 111 and is made of a valve metal oxide such as niobium pentoxide or tantalum pentoxide.

The solid electrolyte layer 113 is formed so as to fill the pores 160 of the porous sintered body 111. Further, as shown in FIG. 1B, at least a part of the surface of the capacitor element 110 shown in FIG. 1A is formed. It is formed so as to cover it. The solid electrolyte layer 113 of the present invention is a conductive layer mainly composed of a mixture of a conductive polymer and a photocurable polymer, and is a layer formed by photocuring a treatment liquid 200 described later.

The cathode lead layer 114 is a laminate of, for example, a graphite layer 114 a and a silver layer 114 b and covers the solid electrolyte layer 113. That is, as shown in FIG. 1B, the capacitor element 110 is formed so as to cover at least a part of the surface thereof.

The cathode lead layer 114 shown in FIG. 1A is bonded to one main surface of the cathode terminal 130b via a conductive adhesive 140 made of, for example, silver paste, whereby the solid electrolyte layer 113 and the cathode terminal 130b are joined together. Conducted.

  The anode lead 115 shown in FIG. 1A is made of a valve metal such as tantalum or niobium, and is made of the same metal as the valve metal fine powder forming the porous sintered body 111. Further, as shown in FIG. 1A, a part thereof has entered the porous sintered body 111.

The electrode substrate 130 is a plate-like member obtained by plating, for example, Cu on a base material made of a Ni alloy such as 42 alloy, and includes an anode terminal 130a and a cathode terminal 130b. One main surface of the anode terminal 130 a is electrically connected to the anode lead 115 through the metal strip 120. Further, the other main surface of the anode terminal 130 a is exposed from the sealing resin 150 and functions as a mounting surface of the solid electrolytic capacitor 100. One main surface of the cathode terminal 130b is bonded to the cathode lead layer 114 via the conductive adhesive 140 as described above. Further, the other main surface of the cathode terminal 130 b is exposed from the sealing resin 150 and functions as a mounting surface of the solid electrolytic capacitor 100.

  The sealing resin 150 is made of, for example, epoxy resin and covers at least one main surface of the capacitor element 110, the metal strip 120, the anode lead 115, and the electrode substrate 130, and protects them. The other main surface of the electrode substrate 130 that is not covered with the sealing resin 150 is used for surface mounting the solid electrolytic capacitor 100.

  Next, an example of a method for manufacturing the solid electrolytic capacitor 100 will be described below with reference to FIGS.

  First, a fine powder of valve action metal such as tantalum or niobium is pressure-molded together with the anode lead 115, and the resulting molded product is subjected to a sintering treatment to obtain a porous sintered body 111. Next, the dielectric layer 112 is formed by subjecting the porous sintered body 111 to an anodizing process in a state where the porous sintered body 111 is immersed in an aqueous phosphoric acid solution, for example.

  FIG. 2 shows an impregnation step in the method for producing a solid electrolytic capacitor according to the present invention. In this residence, a treatment liquid 200 is prepared. The treatment liquid 200 in the present invention includes a conductive polymer, a photocurable polymerizable liquid, an additive, and the like.

  Next, as shown in FIG. 2, the treatment liquid 200 is impregnated with the porous sintered body 111 of the capacitor element 110 on which the dielectric layer 112 is formed. By this impregnation, the treatment liquid 200 penetrates into the pores 160 of the porous sintered body 111. By penetrating, the solid electrolyte layer 113 (not shown in FIG. 2) generated as a result of the photocuring step described later can cover the dielectric layer 112 (not shown in FIG. 2) without a gap. Subsequently, the porous sintered body 111 is pulled up from the processing liquid 200. At this time, the treatment liquid 200 that has excessively adhered to the porous sintered body 111 can be subjected to, for example, a centrifugal force or a wiping process.

  In addition, it replaces with the process of osmosis | permeating the process liquid 200 to the pore 160 which a porous sintered compact has, and the formation method of the solid electrolyte layer 113 in a conventional method can also be used together. Specifically, the solid electrolyte layer is formed by the oxidation polymerization described above, or the porous sintered body 111 of the capacitor element 110 is impregnated with the dispersion solution of the conductive polymer dispersion described above, followed by drying of the solvent. This is a method of forming a solid electrolyte layer. Even in combination with the prior art, by applying the method disclosed in the present invention to the outermost layer, that is, the solid electrolyte layer formed on the surface of the porous sintered body 111, a uniform solid electrolyte membrane is additionally formed on the outermost layer. Thus, the effects of the present invention such as reduction of ESR and prevention of device defects can be sufficiently expected.

FIG. 3 shows a photocuring process subsequent to the impregnation process shown in FIG. The photocuring step is a step for curing the treatment liquid 200 that has permeated and adhered to the porous sintered body 111 to form the solid electrolyte layer 113, for example. The porous sintered body 111 to which the treatment liquid 200 is attached is irradiated with UV light α, and the treatment liquid 200 is photocured. As the light source of the UV light α, for example, a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a xenon arc, a carbon arc, or the like can be used. Through this step, the solid electrolyte layer 113 is formed on the pores 160 of the porous sintered body 111 and the surfaces thereof.

Depending on the film thickness and other conditions, the impregnation step and the subsequent photocuring step can be repeated as many times as desired. However, since the solid electrolyte membranes formed in each repetition process do not completely unite, and an interface is formed, it is desirable to avoid repetition as much as possible because an interface resistance derived from this may occur. . In addition, as a feature of the present invention, since the solid electrolyte layer 113 is formed using a photocuring reaction having a high curing rate, the treatment liquid 200 can be thickly coated and molded to a desired film thickness. As a result, there is no need for repeated coating, and a solid electrolyte layer 113 having a sufficient thickness can be prepared.

Since the photocuring reaction used in the present invention has a fast curing speed and excellent moldability, the formed solid electrolyte layer 113 is uniformly formed on the porous sintered body 111 of the capacitor element 110. By forming the solid electrolyte layer 113 uniformly, the defective portion of the solid electrolyte region, for example, the defective portion X shown in FIG. This defect is, for example, an increase in ESR, and other causes such as disconnection due to current concentration at the defect site.

  After the step of forming the solid electrolyte layer 113 by photocuring, there may be a step of assisting the curing reaction of the polymer film, that is, the solid electrolyte layer 113 by heating, depressurizing, or the like as desired.

Thereafter, the cathode lead layer 114 is formed by laminating the graphite layer 114a and the silver layer 114b on the solid electrolyte layer 113 shown in FIG. 1B. Subsequently, the anode lead 115 is welded to the metal strip 120 using, for example, a laser welding method. Further, the metal strip 120 is joined to the anode terminal 130 a by, for example, resistance welding, and the cathode lead layer 114 is joined to the cathode terminal 130 b using the conductive adhesive 150.

  Subsequently, the sealing resin 150 is molded using, for example, an epoxy resin material. The solid electrolytic capacitor 100 is completed through the above steps.

<Composition of treatment liquid 200>
The treatment liquid 200 in the present invention comprises a conductive polymer, a dopant, a photocurable polymerizable liquid, a photopolymerization initiator, other additives, and the like. Details of the composition of the treatment liquid 200 in the present invention will be described below.

<Conductive polymer>
Examples of the conductive polymer monomer include pyrrole, thiophene, aniline, and derivatives thereof. By polymerization of the monomer, a π-conjugated conductive polymer having a monomer repeating unit can be obtained. Therefore, by using the monomer, a conductive polymer composed of, for example, polypyrroles, polythiophenes, polyanilines, and copolymers thereof can be obtained. The π-conjugated conductive polymer can obtain sufficient conductivity even if it is not substituted, but in order to further increase the conductivity, an alkyl group, a carboxylic acid group, a sulfonic acid group, an alkoxyl group, a hydroxyl group It is preferable to introduce a functional group such as a cyano group into the π-conjugated conductive polymer.

Specific examples of such π-conjugated conductive polymer monomers include, for example, pyrrole, N-methylpyrrole, 3-methylpyrrole, 3-octylpyrrole, 3-decylpyrrole, 3-dodecylpyrrole, 3,4- Dimethylpyrrole, 3,4-dibutylpyrrole, 3-carboxypyrrole, 3-methyl-4-carboxypyrrole, 3-methyl-4-carboxyethylpyrrole, 3-methyl-4-carboxybutylpyrrole, 3-hydroxypyrrole, 3 -Pyrroles such as methoxypyrrole and 3,4-ethylenedioxypyrrole, thiophene, 3-methylthiophene, 3-hexylthiophene, 3-heptylthiophene, 3-octylthiophene, 3-decylthiophene, 3-dodecylthiophene, 3 -Octadecylthiophene, 3-bromothiooff 3,4-dimethylthiophene, 3,4-dibutylthiophene, 3-hydroxythiophene, 3-methoxythiophene, 3-ethoxythiophene, 3-butoxythiophene, 3-hexyloxythiophene, 3-heptyloxythiophene, 3- Octyloxythiophene, 3-decyloxythiophene, 3-dodecyloxythiophene, 3-octadecyloxythiophene, 3,4-dihydroxythiophene, 3,4-dimethoxythiophene, 3,4-ethylenedioxythiophene, 3,4-propylene Dioxythiophene, 3,4-butenedioxythiophene, 3-carboxythiophene, 3-methyl-4-carboxythiophene, 3-methyl-4-carboxyethylthiophene, 3-methyl-4-carboxybutylthiophene, etc. Examples include offene-based, aniline, 2-methylaniline, 3-isobutylaniline, 2-anilinesulfonic acid, and polyaniline-based 3-anilinesulfonic acid. Among π-conjugated conductive polymers composed of these, polypyrrole, polythiophene, poly (N-methylpyrrole), poly (3-methylthiophene), poly (3-methoxythiophene), poly (3,4-ethylenedioxy) A polymer or copolymer consisting of one or two selected from (thiophene) is preferably used from the viewpoint of electrical conductivity. Furthermore, polypyrrole and poly (3,4-ethylenedioxythiophene) are more preferable from the viewpoint of higher conductivity and improved heat resistance.

<Dopant>
In order for the conductive polymer to have conductivity, it is desirable to add a dopant. The dopant to be added is, for example, an electron-accepting compound, and more specifically, for example, a Lewis acid compound. For example, halogen ions such as Cl ⁻ , Br ⁻ and I ⁻ , HSO ₄ ⁻ , R—SO, and the like. ₄ ^- (R is an alkyl group, an aryl group, or an alkenyl group) sulfate compounds such anions, benzenesulfonate ion, p-toluenesulfonic acid ion, naphthalenesulfonic acid, butyl naphthalene sulfonic acid ion, and a dodecylbenzenesulfonic acid ion Aromatic sulfonate anions, nitrate ions, nitrate ions, acetate ions and the like.

  As the dopant, for example, a dopant having paratoluenesulfonate ion, for example, pyridinium paratoluenesulfonate, is desirable for oxidation resistance. In principle, this dopant can simultaneously serve as a photopolymerization initiator for assisting the curing of the photocurable component described later.

<Photocurable polymerizable liquid>
The photocurable polymerizable liquid used in the present invention is prepared as a monomer, oligomer, or polymer having a photocurable functional group, alone or as a mixture thereof. It is prepared as a liquid single compound or composition containing. These are suitably selected and blended in view of their reactivity, compatibility with the conductive polymer and other components, the viscosity of the liquid monomer or composition, and the conductivity of the resulting solid electrolyte layer. Further, the polymer may be a so-called copolymer having two or more types of monomer units.

Examples of the liquid polymer having a photocurable functional group include an oligomer or a prepolymer or a polymer such as polyester, epoxy resin, oxetane resin, polyacryl, polyurethane, polyimide, polyamide, polyamideimide, and polyimide silicone. Examples of the monomer constituting the photocurable liquid polymer include bisphenol A / ethylene oxide-modified diacrylate, dipentaerythritol hexa (penta) acrylate, dipentaerythritol monohydroxypentaacrylate, dipropylene glycol diacrylate, and trimethylol. Propane triacrylate, glycerin propoxy triacrylate, 4-hydroxybutyl acrylate, 1,6-hexanediol diacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobornyl acrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate , Tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate Acrylates such as tripropylene glycol diacrylate, tetraethylene glycol dimethacrylate, alkyl methacrylate, allyl methacrylate, 1,3-butylene glycol dimethacrylate, n-butyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, diethylene glycol dimethacrylate, 2-ethylhexyl methacrylate , Methacrylates such as glycidyl methacrylate, 1,6-hexanediol dimethacrylate, 2-hydroxyethyl methacrylate, isobornyl methacrylate, lauryl methacrylate, phenoxyethyl methacrylate, t-butyl methacrylate, tetrahydrofurfuryl methacrylate, trimethylolpropane trimethacrylate Allylic Glycidyl ethers such as cidyl ether, butyl glycidyl ether, higher alcohol glycidyl ether, 1,6-hexanediol glycidyl ether, phenyl glycidyl ether, stearyl glycidyl ether, 3-ethyl-3-hydroxymethyloxetane, 3- (meth) allyl Oxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy) methylbenzene, 4-fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, [1- (3-ethyl- 3-oxetanylmethoxy) ethyl] phenyl ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl , Bornyl (3-ethyl-3-oxetanylmethyl) ether, 3- (4-bromobutoxymethyl) -3-methyloxetane, (3-methyloxetane-3-yl) methylbenzoate, 3,7-bis (3 -Oxetanyl) -5-oxa-nonane, 3,3 '-(1,3- (2-methylenyl) propanediylbis (oxymethylene)) bis- (3-ethyloxetane), 1,4-bis [(3 -Ethyl-3-oxetanylmethoxy) methyl] benzene, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] biphenyl, 1,2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] Ethane, 1,3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, trimethylolpropane tris (3-ethyl-3-oxetani Methyl) ether, 1,4-bis (3-ethyl-3-oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ) Ether, caprolactone-modified dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropanetetrakis (3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol A bis (3-ethyl-3-) Oxetanylmethyl), poly (3- (4-bromobutoxymethyl) -3-methyloxetane), N-oxetan-2-ylmethoxymethylacrylamide, 3,5-bis (3-ethyl-3-oxetanylmethoxy) benzoic acid 3,5-bis (3-ethyl-3 Oxetane series such as oxetanylmethoxy) benzoic acid methyl ester, 5- (3-ethyl-3-oxetanyl) isophthalic acid, 1,1,1-tris [4 (3-ethyl-3-oxetanylmethoxy) phenyl] ethane, 2 -Monofunctional monomers of vinyl ethers such as chloroethyl vinyl ether, cyclohexyl vinyl ether, ethyl vinyl ether, hydroxybutyl vinyl ether, isobutyl vinyl ether, and triethylene glycol vinyl ether, and monofunctional monomers of carboxylic acid vinyl esters such as vinyl butyrate, vinyl monochloroacetate, and vinyl pivalate. A functional monomer is mentioned.

The curing reaction by light energy is divided into a radical polymerization type and a cationic polymerization type depending on the curing mechanism. Therefore, the photocurable polymerizable liquid is also classified into a radical polymerization type and a cationic polymerization type.

Among the monomers constituting the liquid polymer having photocurability, the main components listed above, in particular, acrylate-based and methacrylate-based are radical polymerization types, and glycidyl ether-based, that is, epoxy-based, octacene-based, vinyl ether-based cationic polymerization types. It is.

<Photopolymerization initiator>
A photopolymerization initiator and a photocurable polymerizable liquid are polymerized and cross-linked and cured. The photopolymerization initiator is an additive that generates a chemical species for initiating photoradical polymerization or photocationic polymerization by receiving light energy rays such as ultraviolet rays. Therefore, a photopolymerization initiator can be added to the photocurable polymerizable liquid according to the present invention as necessary. Examples of the photopolymerization initiator include radical polymerization initiators such as acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethylthiuram monosulfide, and thioxanthones. Moreover, as cationic polymerization initiators, onium salts such as aryldiazonium salts, diarylhalonium salts, and triphenylsulfonium salts are preferable, and examples include silanol / aluminum chelates and α-sulfonyloxyketones. Furthermore, n-butylamine, triethylamine, tri-n-butylphosphine, or the like can be mixed as a photosensitizer. The photopolymerization initiator is preferably contained in the composition of the photocurable polymerizable liquid of the present invention in an amount of 0.1 to 15% by mass, more preferably 0.2 to 12% by mass, and 0.3 to 10% by mass. % Is more preferable. In particular, the conductive polymer has a property of substantially absorbing light, and thus affects photocurability. In consideration of this point, it is necessary to adjust the amount of the photopolymerization initiator.

Particularly desirable as a photopolymerization initiator according to the present invention is a photocurable polymerizable liquid of a so-called low curing shrinkage, and a cationic polymerization type is desirable for this. Furthermore, the cationic polymerization type photo-curable liquid polymer is desirable in adapting to the present invention because it does not inhibit surface curing by oxygen and enables thin film curing.

Therefore, the photocurable polymerizable liquid according to the present invention is, for example, a photocurable polymerizable liquid composed of one or more monomers, oligomers or polymers selected from the group consisting of epoxy-based, oxetane-based, and vinyl ether-based compounds. It is preferable to use epoxy, more preferably an epoxy type and an oxetane type, and particularly preferably an oxetane type. By using a compound having an epoxy-based or oxetane-based cyclic structure, the adhesion and photocurability of the solid electrolyte layer 113 formed on the element surface are particularly excellent. This is because a compound having an epoxy ring or an oxetane ring has a small volume change before and after the polymerization reaction and high reactivity. In the case of radical polymerization type polymerization, a new carbon-carbon bond is formed between the molecules during the polymerization reaction, and the intermolecular distance is reduced, resulting in a decrease in the bulk of the entire polymer cured product molecule produced. To do. On the other hand, in the case of cationic polymerization type polymerization, particularly ring-opening polymerization, the bond breaks due to the ring-opening reaction, that is, the molecule spreads in a chain and the formation of bonds occurs at the same time. There is little change. As a result, since distortion caused by volume change does not occur, deterioration of the adhesion of the solid electrolyte layer 113 to the element surface can be prevented. In addition to the epoxy-based and oxetane-based liquid polymers, a vinyl ether-based liquid polymer that is also a cationic polymerization type can be preferably blended. In addition, a radical polymerization type compound can be used in combination as long as the effects of the present invention are not impaired.

In the photocurable polymerizable liquid of the present invention, among the photopolymerizable compounds listed above, in particular, the monomer is usually used as a reactive diluent to reduce the viscosity of the photocurable composition of the present invention. It is effective and is added in the range of preferably 95% by mass or less, more preferably 90% by mass or less, and particularly preferably 85% by mass or less of the photocurable polymerizable liquid. By making the ratio of the monomer 95% by mass or less, the mechanical strength and heat resistance of the cured film can be kept better. On the other hand, since the monomer is used as a reactive diluent, it is usually essential for the photocurable polymerizable liquid of the present invention, preferably 1% by mass or more of the total photocurable polymerizable liquid, more preferably 3% by mass or more, more preferably 5% by mass or more.

<Organic solvent>
The organic solvent contained in the treatment liquid 200 of the present invention is in the range of 2% by mass or less, more preferably 0.5% by mass or less, and particularly preferably not contained in the treatment liquid 200. In particular, in the composition of the liquid polymer having photocurability according to the present invention, the monomer or oligomer has a role as a diluent liquid as well as a role as a reactive liquid. Such an organic solvent for dissolving other elements contained in the processing liquid 200 is not necessarily included. More specifically, monomers, oligomers and polymers can be considered as a group of substances having the same photoreactive functional group. Generally, the lower the degree of polymerization, the lower the viscosity of the substance. The degree of polymerization is the number of times that the repeating structure constituting the oligomer or polymer is repeated. Therefore, without using a solvent, for example, by increasing the amount of monomer, it is possible to sufficiently reduce the viscosity of the entire processing liquid 200.

As an advantage of not using an organic solvent, since the baking process for the purpose of volatilization of the organic solvent is unnecessary in the step of forming the solid electrolyte layer 113, productivity improvement, space saving, energy saving and the like can be expected. Furthermore, since it is possible to use a process that does not use organic solvents, the chemical substance release and transfer notification system (PRTR, Pollutant Release and Transfer)
Registen) and volatile organic compound (VOC) regulations can be easily dealt with. On the other hand, in a process using a large amount of organic solvent, as described above, a change in the volume of the solid electrolyte film made of a conductive polymer due to volatilization and drying of the organic solvent tends to reduce the adhesion of the film to the element.

However, an organic solvent may be optionally added from the viewpoints of coatability, reactivity during photocuring reaction, solubility of conductive polymer, and the like. The organic solvent that can be suitably used in the treatment liquid 200 of the present invention is generally used for dissolving a conductive polymer, diluting a photoresist, a photocurable resin, or the like. Any component can be used as long as it has an effect of dissolving the components contained in 200 and uniformly dispersing the components in the solution and is not reactive with the components of the treatment solution 200.

In addition, the treatment liquid 200 of the present invention preferably contains, as additives, an antioxidant for preventing deterioration of the conductive polymer, a surfactant for preventing poor coating such as uneven coating of the solid electrolyte membrane, and the like. Can do.

<Composition of treatment liquid 200>
The processing liquid 200 is configured by suitably blending and mixing the constituent elements of the processing liquid 200 listed above. The treatment liquid 200 as a raw material for the solid electrolyte layer 113 in the present invention is composed of at least a conductive polymer and a photocurable polymerizable liquid.

Furthermore, although preferable blend forms, such as a conductive polymer, a photocurable polymerizable liquid, and an additive, in the treatment liquid 200 of the present invention will be described, the range of the blend of polymerizable monomers is not particularly limited thereto. . In the treatment liquid 200 of the present invention, the blending ratio of each component is selected from the viewpoints of ESR reduction, conductivity, and mechanical strength. In particular, the ESR reduction or conductivity depends on the blending amount of the conductive polymer and the dope amount, and the mechanical strength, curing speed, adhesion and the like mainly depend on the blending of the photocurable polymerizable liquid. In order to obtain the effect according to the present invention, the treatment liquid 200 preferably contains the conductive polymer in the range of 20% by mass to 90% by mass, and more preferably 30% by mass to 70% by mass. Moreover, it is preferable that a photocurable polymerizable liquid is contained in the range of 10 mass%-70 mass%, and also 20 mass%-50 mass% are preferable.

The above components can be sequentially formed as a laminate without being a mixture. Preferably, at least the conductive polymer and the photocurable polymerizable liquid are a mixture, and more preferably This is the case when everything is a mixture. This is because the number of steps increases and the operation becomes complicated when the lamination process is performed, the influence of the interface formed between the lamination layers, and the drying and swelling by the solvent are repeated, resulting in film uniformity and adhesion. This is because problems such as damage may be caused. However, a method of making the above constituent components into a laminated structure can be used in combination as long as the effects of the present invention are not impaired.

<About thermosetting polymerizable liquid>
The photocurable liquid component according to the present invention is a component that can be cured and molded by stimulation of light, but in the sense of such a stimulus-responsive curing component, a component that is cured by heat, such as a so-called thermosetting resin Is widely used. As an alternative to the photocurable polymerizable liquid according to the present invention, it may be possible to use the thermosetting polymerizable liquid, but when using only the thermosetting polymerizable liquid as the curing component according to the present invention, For this reason, it is not always preferable. For example, a thermosetting component of a type that requires a high temperature for curing is excellent in heat resistance and easy to control the reaction, but may cause thermal stress on the capacitor element portion. On the other hand, for those which can be cured at room temperature or lower temperature, it is easy to cure at room temperature, so it is necessary to pay attention to, for example, temperature management, and there is a risk that handling may be deteriorated and the process becomes complicated.

In addition, it is difficult to achieve a method of forming a conductive film made of a conductive polymer at an arbitrary position, that is, formation of a site-selective solid electrolyte layer with only a thermosetting component. However, a thermosetting liquid component or a thermal polymerization initiator can be mixed as needed within a range not impairing the effects of the present invention.

<Modification of manufacturing process of solid electrolytic capacitor>
Modification examples of the solid electrolytic capacitor that is considered to be particularly effective by using the present invention will be described below.

  FIG. 5 shows a modified example of the photocuring process that enables the solid electrolyte layer to be formed at an arbitrary location of the capacitor element as a modified example.

  More specifically, FIG. 5 shows a state in which a solid electrolyte membrane is selectively formed at the apex of the porous sintered body 111 whose main part is a rectangular parallelepiped shape.

  Prior to the photocuring step shown in FIG. 5, the treatment liquid 200 is impregnated with the porous sintered body 111 of the capacitor element 110 on which the dielectric layer 112 is formed by performing the impregnation step shown in FIG. 2. The capacitor element 110 used at this time may be in a state in which the dielectric layer 112 is formed on the porous sintered body 111 or may be formed by further forming the solid electrolyte layer 113. The method is as described above. The described method of the present invention may be used, and the solid electrolyte layer 113 may be formed by the method exemplified in the conventional invention.

Subsequently, the porous sintered body 111 is pulled up from the processing liquid 200. At this time, the treatment liquid 200 that has excessively adhered to the porous sintered body 111 can be subjected to, for example, a centrifugal force or a wiping process.

  Subsequently, as a photocuring step, a spot light source 310 may be prepared as shown in FIG. The spot light source 310 is a light source device that can generate a light intensity sufficient for the photocuring reaction of the processing liquid 200 and has a mechanism that can arbitrarily squeeze the light irradiation region. And a photoresist exposure means used in the manufacture of semiconductors.

  Now, the treatment liquid 200 is uniformly applied to the surface of the porous sintered body 111, for example. On the other hand, the spot light source 310 is irradiated to an arbitrary place.

  After performing the photocuring reaction with the spot light source 310, the capacitor element 110 may be subjected to a cleaning operation with an appropriate solvent. At this time, since only the portion exposed by the spot light source 310 is cured, only the portion remains in the capacitor element 110, and the uncured portion, that is, the excess processing liquid 200 is removed by this cleaning operation.

  The site-selective solid electrolyte layer 226 is formed in this way. The site-selective solid electrolyte layer 226 may be formed, for example, in such a manner that the solid charged lipid 113 covers a portion where the apex portion of the porous sintered body 111 is deficient, that is, the defective portion X. . As a result, it is possible to prevent defects caused by the defective portion X, for example, increase of ESR, disconnection at the defective portion X due to overcurrent, and the like.

  The effectiveness of the present invention will be described by comparing FIG. 5 and FIG.

  The site-selective solid electrolyte layer 226 is selectively formed only around the defect portion X as described above, for example, so that an extra solid electrolyte membrane is formed as compared with the case where the capacitor element 110 is formed as a whole. Since it is not formed, problems such as an increase in ESR due to overcoating do not occur. The extra solid electrolyte layer referred to in this section is a portion where the solid electrolyte layer 1130 shown in FIG. 7 is a multilayer.

More specifically, as shown in FIG. 1A, one main surface of the capacitor element 110 is joined to the cathode terminal 130b via the conductive polymer 140, but the solid electrolyte layer has a multilayer structure as shown in FIG. It is conceivable that an interface is formed by this, and this becomes an interface resistance. Therefore, it is desirable not to laminate a solid electrolyte layer on the main surface. By using the method of the present invention, as shown in FIG. 5, formation of a solid electrolyte layer with high positional accuracy by an easy operation without providing an extra laminated film on the main surface, that is, the apex of the capacitor element 110. Since the selective formation to the part can be performed, the above problem is solved.

Furthermore, the excess processing liquid 200 removed by the cleaning operation in the above process can be reused by distilling off the solvent used for cleaning, leading to a reduction in materials used and cost reduction. .

  As a method for assisting the formation of the selective solid electrolyte layer, or even for the purpose of uniform coating, generally known coating processes other than the impregnation process, such as an inkjet method, a drop cast method, an air knife coating method, A curtain coating method, a wire bar coating method, a gravure coating method, an extrusion coating method, a spin coating method, a slit scanning method, or the like can be suitably used or used in combination with an impregnation step. In addition to the effect of improving the selectivity of the film-forming site, these methods are effective in reducing raw material costs because the amount of the treatment liquid 200 can be limited.

  In the above and FIG. 5, the example in which the site selective solid electrolyte layer 226 is sequentially formed on the capacitor element 110 on which the solid electrolyte layer 113 is formed is shown. Then, the solid electrolyte layer 113 may be formed using the method of the present invention, and the method used in the conventional invention, for example, the oxidation polymerization described above, as long as the effects of the present invention are not impaired. A method of forming a solid electrolyte layer by the above-mentioned method, or a method of impregnating the porous sintered body 111 of the capacitor element 110 in the dispersion solution of the conductive polymer dispersion described above, and subsequently forming a solid electrolyte layer by drying the solvent. .

  Since the solid electrolytic capacitor of the present invention has a solid electrolyte layer having a stable shape and excellent adhesion, the ESR can be reduced and the defect occurrence rate is low, so that the industrial applicability is great.

DESCRIPTION OF SYMBOLS 100 Solid electrolytic capacitor 110 Capacitor element 111 Porous sintered body 112 Dielectric layer 113, 1130 Solid electrolyte layer 114 Cathode extraction layer 114a Graphite layer 114b Silver layer 115 Anode lead-out lead 116 Swelling prevention means 120 Metal strip 130 Electrode substrate 130a Anode terminal 130b Cathode terminal 140 Conductive adhesive 150 Sealing resin 160 Pore 200 Treatment liquid 310 Spot light source α UV light Z, Z2, Z3, Z4, Z5

Claims (12)

Made of valve action metal, a rectangular parallelepiped porous sintered body,
A dielectric layer covering at least a part of the porous sintered body;
A solid electrolyte layer covering at least a part of the dielectric layer;
A solid electrolytic capacitor comprising:
At least one part of the said solid electrolyte layer is laminated | stacked so that it may have a layer which does not contain photocurable resin, and a layer containing photocurable resin, The solid electrolytic capacitor characterized by the above-mentioned.   The layer that does not contain the photocurable resin of the solid electrolyte layer is thinner than the other parts at the apex part of the rectangular parallelepiped shape, and the layer containing the photocurable resin is at the apex part of the rectangular parallelepiped shape, The solid electrolytic capacitor according to claim 1, wherein the solid electrolytic capacitor is formed to be thicker than other portions.   The solid electrolytic capacitor according to claim 1, further comprising a cathode lead layer that covers the solid electrolyte layer.   The solid electrolytic capacitor according to claim 3, wherein the solid electrolytic capacitor has a portion where the layer not containing the photocurable resin and the cathode lead layer are in contact with each other. The solid electrolytic capacitor according to claim 1, wherein the photocurable component is a cationic polymerization type photocurable component. A step of forming a rectangular parallelepiped porous sintered body made of a valve metal,
Forming a dielectric layer covering at least a part of the porous sintered body;
Forming a solid electrolyte layer covering at least a part of the dielectric layer, and a method for producing a solid electrolytic capacitor comprising:
In the step of forming the solid electrolyte layer,
Forming a solid electrolyte layer that does not contain a photocurable resin; and
Applying a treatment liquid containing a conductive polymer and a photocurable component;
Of the applied treatment liquid, a process of removing excess,
Having a step of forming a solid electrolyte layer by photocuring,
A method for producing a solid electrolytic capacitor. In the above treatment liquid,
A conductive polymer;
A dopant for adjusting the conductivity of the conductive polymer;
A photocurable component;
A photopolymerization initiator that aids photocuring of the photocurable component, and
The method for producing a solid electrolytic capacitor according to claim 6, wherein the solid electrolytic capacitor is a mixture containing At least in the treatment liquid,
20-80% by mass of a conductive polymer,
The method for producing a solid electrolytic capacitor according to claim 6 or 7, wherein the mixture comprises 10 to 70% by mass of a photocurable polymerizable liquid. In the above treatment liquid,
An antioxidant that protects the function of the conductive polymer;
The method for producing a solid electrolytic capacitor according to claim 7, comprising at least one of surfactants that prevent application failure. The method for producing a solid electrolytic capacitor according to any one of 6 to 9, wherein the treatment liquid can contain an organic solvent for adjusting coating properties. The photocurable component is a monomer, oligomer or polymer having a photocurable functional group, alone or a mixture thereof.
A liquid single compound or composition comprising one or more compounds,
It is a liquid, The manufacturing method of the solid electrolytic capacitor as described in any one of Claims 6-10 characterized by the above-mentioned. In the step of forming a solid electrolyte layer by photocuring,
Applying the treatment liquid to part or all of the element;
Selectively irradiating a part of the applied treatment liquid with a curing light source;
Washing off the excess treatment liquid not cured in the above steps;
The method for producing a solid electrolytic capacitor according to claim 6, further comprising:

that's all

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