JP2012015425A - Solid electrolytic capacitor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the ESR and a capacitance appearance rate of a solid electrolytic capacitor in which a conductive polymer layer is formed, and to reduce manufacturing costs in a method of soaking a conductive polymer compound in aqueous dispersion.SOLUTION: On an anode conductor 1 of valve action metal powder and a dielectric layer 2 formed on the surface of the anode conductor 1, a solid electrolyte layer 4 is formed of a conductive polymer layer which is formed by soaking in or coating with aqueous dispersion of a conductive polymer compound and then drying. Subsequently, a graphite layer 5A and a silver conductive resin layer 5B are formed as an anode conductor 5. Thereafter, heat treatment is performed at a temperature equal to or higher than the highest one of glass transition temperature and a melting point of a polymer resin contained in the solid electrolyte layer, the graphite layer and the silver conductive resin layer.

Description

  The present invention relates to a solid electrolytic capacitor and a method for producing the same, and more specifically, a solid electrolytic capacitor that is impregnated in a dispersion aqueous solution of a conductive polymer compound, has excellent ESR, capacity appearance rate, and withstand voltage characteristics, and can be manufactured in a short process It relates to a manufacturing method.

  After a dielectric oxide film layer is formed by electrolytic oxidation on a porous body of valve action metal such as tantalum, aluminum, titanium, niobium, zirconium, etc., a conductive polymer layer is formed on the oxide film. Solid electrolytic capacitors that are solid electrolytes have been developed. As a method for forming the conductive polymer layer of this solid electrolytic capacitor, there are a chemical oxidative polymerization method, an electrolytic oxidative polymerization method, and a method of impregnating a dispersed aqueous solution of a conductive polymer compound.

  First, in a method for forming a conductive polymer by chemical oxidative polymerization, a capacitor anode conductor is made of a monomer represented by pyrrole, thiophene, 3,4-ethylenedioxythiophene or aniline constituting a conductive polymer material (single amount). Body) and an aqueous solution containing an oxidizing agent such as peroxodisulfuric acid in turn, or by impregnating a mixed aqueous solution of a monomer and an oxidizing agent to cause a polymerization reaction, and a dielectric oxide film layer A conductive polymer layer made of a polymer (polymer) such as polyethylenedioxythiophene is formed thereon.

  This formation method can obtain a high capacity appearance rate when forming the solid electrolytic capacitor. However, the dielectric oxide film layer is dissolved, deteriorated, or lost due to the polymerization reaction, and the dielectric oxide film layer is thinned as a whole or locally. May occur. In addition, it is impregnated with an aqueous solution containing a monomer and an aqueous solution containing an oxidizing agent individually, or after being impregnated with a mixed aqueous solution containing a monomer and an oxidizing agent, followed by repeated room temperature drying, acid cleaning, and high temperature drying. In the polymerization method, the number of steps required to form the conductive polymer layer increases.

  In the method of forming a conductive polymer by electrolytic oxidation polymerization, a capacitor anode conductor is formed by using a monomer represented by pyrrole, thiophene, 3,4-ethylenedioxythiophene, aniline, and paratoluenesulfonic acid that constitute the conductive polymer material. Impregnation into a mixed solution containing a supporting electrolyte typified by naphthalene sulfonic acid and applying a constant current or a constant voltage for a certain period of time to cause a polymerization reaction, and on the dielectric oxide film layer, polyethylene dioxythiophene A conductive polymer layer made of a polymer (polymer) such as is formed.

  This forming method can provide the same capacity appearance rate, ESR, and breakdown voltage as the chemical oxidation polymerization method when forming the solid electrolytic capacitor. The number of steps required to form the conductive polymer layer is equal to or greater than the method of impregnating the aqueous dispersion of the conductive polymer compound. However, the electrolytic oxidation polymerization method controls the current or voltage and has little variation within the same batch, and it is difficult to form a conductive polymer layer having a uniform thickness on the dielectric oxide film layer. It has the feature that it becomes difficult as it gets smaller. For this reason, a production facility for a solid electrolytic capacitor using an electrolytic oxidation polymerization method has a problem that a large capital investment is required as compared with other construction methods.

  In addition, the method of impregnating the aqueous dispersion of the conductive polymer compound is a method in which the anode conductor of the capacitor is impregnated with the aqueous dispersion of the conductive polymer compound and then dried to directly form the solid electrolyte layer on the anode. .

  Since this forming method simply repeats impregnation of the conductive polymer compound into the dispersion aqueous solution and drying, the number of steps for forming the conductive polymer layer is significantly less than that of the above-described chemical oxidation polymerization method. It has the characteristics. However, since the polymer has a larger particle size than the monomer, it does not easily penetrate into the deep part of the pores made of the porous metal of the valve action metal, and the ESR and the capacity appearance rate cannot be obtained sufficiently. Yes.

  Therefore, a method of obtaining a solid electrolytic capacitor by combining a chemical oxidative polymerization method and a method of impregnating a dispersion aqueous solution of a conductive polymer compound is disclosed.

  Also disclosed is a technique for performing heat treatment (above the thermal decomposition temperature of the carbon paste resin of the carbon layer constituting the capacitor element) on the capacitor element formed in the capacitor manufacturing process in order to improve the electrical characteristics of the capacitor. ing.

  The method for forming such a solid electrolytic capacitor is disclosed in the following patent document.

  In Patent Document 1, a first conductive polymer layer is formed by a chemical oxidative polymerization method, and then a second conductive polymer layer is formed by a method of impregnating in a dispersion aqueous solution of a conductive polymer compound. A technique for performing a oxidative polymerization method to form a third conductive polymer layer is described.

  Patent Document 2 discloses a technique in which a first conductive polymer layer is formed by a method of impregnating a dispersion aqueous solution of a conductive polymer compound and then a second conductive polymer layer is formed by a chemical oxidative polymerization method. Are listed.

  Patent Document 3 discloses a technique for performing heat treatment at a temperature equal to or higher than the thermal decomposition temperature of the resin contained in the graphfight layer after forming the semiconductor layer and the graphite layer on the valve action metal and before or after forming the silver conductive resin layer. Are listed.

JP 2000-191906 A JP 2001-102255 A JP-A-6-124857

  Various chemical oxidation polymerization methods having an excellent ESR and capacity appearance rate and methods of impregnating a dispersion aqueous solution of a conductive polymer compound having an advantage that the number of steps for producing a capacitor are small have been studied. However, combining the chemical oxidative polymerization method and the method of impregnating the dispersed aqueous solution of the conductive polymer compound may cause an interaction, resulting in insufficient product performance such as ESR, capacity appearance rate, pressure resistance, and The contribution to the reduction of man-hours for manufacturing capacitors is insufficient, and the application to solid electrolytic capacitors as products is limited.

  Also, if the capacitor element formed in the capacitor manufacturing process is heated at a temperature equal to or higher than the thermal decomposition temperature of the constituent resin, excessive thermal decomposition of the polymer resin forming the capacitor element will proceed and the interface will adhere. There is a risk of deteriorating the reliability characteristics of the capacitor element.

  Therefore, the present application provides a solid electrolytic capacitor and a method for improving ESR and capacity appearance rate in a method of impregnating a dispersion aqueous solution of a conductive polymer compound, and further has a high withstand voltage, thereby reducing the number of steps for manufacturing the capacitor. An object is to obtain a solid electrolytic capacitor and a method for manufacturing the same.

  The method for producing a solid electrolytic capacitor of the present invention comprises a step of forming a dielectric layer on the surface of an anode conductor made of valve-acting metal powder, and a surface of the dielectric layer impregnated with an aqueous dispersion of a conductive polymer compound. The step of forming a conductive polymer layer constituting the solid electrolyte layer by applying and drying, and heating after forming a graphite layer and a silver conductive resin layer as a cathode conductor on the surface of the conductive polymer layer The method includes a step of performing processing.

  In the method for producing a solid electrolytic capacitor of the present invention, the heat treatment temperature is equal to or higher than the highest temperature among the glass transition temperature and the melting point of the polymer resin contained in the conductive polymer layer, the graphite layer, and the silver conductive resin layer. It is characterized by that.

  The method for producing a solid electrolytic capacitor of the present invention is characterized in that an average pore diameter of the porous anode conductor is 2.5 times or more and 15 times or less with respect to an average particle diameter of the aqueous dispersion of the conductive polymer compound. To do.

  The method for producing a solid electrolytic capacitor of the present invention is characterized in that the conductive polymer content of the aqueous dispersion of the conductive polymer compound is 0.1 to 10% by mass.

  The method for producing a solid electrolytic capacitor of the present invention includes a step of further containing a polyhydric alcohol in the aqueous dispersion of the conductive polymer compound and performing a heat treatment at a temperature equal to or higher than the melting point of the polyhydric alcohol.

  The method for producing a solid electrolytic capacitor of the present invention is characterized in that the content of the polyhydric alcohol is 0.01 to 10% by mass.

  In the solid electrolytic capacitor of the present invention, the polymer resin is made of polystyrene, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyamide, polyimide, polyamideimide, polyester, poly Ether, polyethylene terephthalate, polycarbonate, polyphenylene oxide, polyurethane, polyacetal, diallyl phthalate, polyacrylate, polymethacrylate, polyacrylonitrile, polytetrafluoroethylene, polybutadiene, polyisoprene, polysiloxane, polycarbonate, cellulose, methylcellulose, ethylcellulose, Fluorine resin, urea resin, silicon resin, phenol resin, melamine resin, epoxy resin, active resin Le resins, alkyd resins, butyral resins, silicone resins, characterized in that it is selected from polylactic acid.

  The solid electrolytic capacitor of the present invention is characterized in that the conductive polymer layer contains a polyhydric alcohol.

  In the solid electrolytic capacitor of the present invention, the polyhydric alcohol is at least one selected from erythritol and pentaerythritol.

  The solid electrolytic capacitor of the present invention is characterized in that the conductive polymer layer includes a polymer and a polyacid made of 3,4-ethylenedioxythiophene and derivatives thereof.

  The solid electrolytic capacitor of the present invention is characterized in that the polyacid is polystyrene sulfonic acid.

  The solid electrolytic capacitor of the present invention is characterized in that the valve metal is at least one selected from aluminum, tantalum, and niobium.

  In order to improve the ESR and capacity appearance rate of the solid electrolytic capacitor in which the conductive polymer layer is formed by the method of impregnating the dispersed aqueous solution of the conductive polymer compound, the method for producing the solid electrolytic capacitor of the present invention is as follows. Thus, the interface resistance between the dielectric layer, the conductive polymer layer, the graphite layer, and the silver conductive resin layer is improved. Furthermore, the electrical resistance in each layer, particularly the electrical resistance in the conductive polymer layer can be reduced.

  In the method for producing a solid electrolytic capacitor of the present invention, since the polymer resin contained in the conductive polymer layer, the graphite layer, and the silver conductive resin layer can be made fluid, the heat treatment temperature is the glass transition temperature and the melting point. It is preferable that it is more than the highest temperature.

  In the method for producing a solid electrolytic capacitor of the present invention, the average particle diameter of the conductive polymer compound in the dispersed aqueous solution is such that the conductive polymer compound penetrates to the deep part of the pores made of the porous body of the valve action metal. Therefore, the average pore diameter of the porous anode conductor is preferably 2.5 times or more and more preferably 4 times or more the average particle diameter of the conductive polymer compound in the aqueous dispersion. Moreover, since the capacity appearance rate obtained at the time of solid electrolytic capacitor formation is saturated, the average pore diameter is preferably 15 times or less of the average particle diameter.

  In the method for producing a solid electrolytic capacitor of the present invention, the conductive polymer content of the dispersed aqueous solution containing the conductive polymer compound can increase the permeability of the dispersed aqueous solution within the pores of the porous body. 1-10 mass% is preferable.

  In the method for producing a solid electrolytic capacitor of the present invention, the polyhydric alcohol is preferably added in an amount of 0.01 to 10% by mass because the aggregated conductive polymer is finely and uniformly dispersed.

  By these treatments, the contact area between the conductive polymer layer, the graphite layer, and the silver conductive resin layer can be increased. Furthermore, the electrical resistance in each layer, particularly the electrical resistance in the conductive polymer layer can be reduced.

  Further, the method of impregnating the aqueous dispersion of the conductive polymer compound does not require a polymerization reaction, so that the dielectric oxide film layer is unlikely to be dissolved, deteriorated, or lost. Furthermore, since only the impregnation and drying of the conductive polymer compound in the dispersion aqueous solution are repeated, the number of steps for forming the conductive polymer layer may be significantly reduced as compared with the chemical oxidation polymerization method described above. It becomes possible.

  By improving the ESR and the capacity appearance rate by the above processing, it is possible to provide a solid electrolytic capacitor excellent in capacity appearance rate, leakage current characteristics, and withstand voltage characteristics and a method for manufacturing the solid electrolytic capacitor in a remarkably small number of steps.

The schematic fragmentary sectional view of the solid electrolytic capacitor produced with the manufacturing method of this invention.

  An embodiment of the present invention will be described. Hereinafter, the structure and manufacturing method of the solid electrolytic capacitor of the present invention will be described. A schematic partial sectional view of a solid electrolytic capacitor produced by the production method of the present invention is shown in FIG.

  The capacitor element generally has a structure in which a dielectric layer 2 made of an oxide layer is formed on the surface of the anode conductor 1 and a solid electrolyte layer 4 and a cathode conductor 5 are sequentially formed.

  The anode conductor 1 is formed of a metal plate having a valve action, a foil or a wire, a sintered body made of metal fine particles having a valve action, or a porous metal subjected to surface expansion treatment by etching.

  Examples of the valve action metal include tantalum, aluminum, titanium, niobium, zirconium, and alloys thereof, and are preferably at least one selected from tantalum, aluminum, and niobium.

  The dielectric layer 2 is a film obtained by electrolytically oxidizing the surface of the anode conductor 1, and the thickness of the oxide film can be adjusted as appropriate by the voltage of electrolytic oxidation.

  The solid electrolyte layer 4 includes at least a conductive polymer layer, and the conductive polymer layer includes, for example, a single amount containing at least one or more of pyrrole, thiophene, 3,4-ethylenedioxythiophene, aniline, and derivatives thereof. In particular, it is preferable to include pyrrole, thiophene, 3,4-ethylenedioxythiophene and derivatives thereof. As the aqueous dispersion containing these conductive polymer compounds, commercially available products can be used.

  The solid electrolyte layer 4 is formed by repeatedly dipping and drying in a dispersion aqueous solution containing a conductive polymer compound. Thereby, the pore size distribution can be arbitrarily adjusted.

  The average particle diameter of the conductive polymer compound in the aqueous dispersion is not particularly limited, but the smaller one can penetrate the conductive polymer compound to the deep part of the pores made of a porous body of the valve metal, preferable. For example, the average pore diameter of the porous anode conductor is preferably 2.5 times or more and 15 times or less with respect to the average particle diameter of the conductive polymer compound in the aqueous dispersion.

  The conductive polymer content of the aqueous dispersion containing the conductive polymer compound is preferably 0.1 to 10% by mass in order to increase the permeability of the aqueous dispersion in the pores of the porous body. In order to prevent the adhesion amount of the conductive polymer and the capacity appearance rate of the capacitor from decreasing, 0.5 to 1.0% by mass is particularly preferable.

  When heat treatment is performed after forming the conductive polymer layer forming the solid electrolyte layer 4, the graphite layer 5A forming the cathode conductor 5, and the silver conductive resin layer 5B, the conductive polymer layer, the graphite layer 5A, and the silver conductive layer are formed. The polymer resin contained in the conductive resin layer 5B is preferable because it can have fluidity.

  The temperature of the heat treatment is not particularly limited, but the heat-resistant deterioration of the resin used in the polymer resin contained in the conductive polymer layer, graphite layer, and silver conductive resin layer constituting the capacitor element is prevented. From this viewpoint, the upper limit temperature is preferably less than 300 ° C. (a temperature at which the thermal decomposition temperature is not reached). Moreover, it is preferable that minimum temperature is more than the temperature with the highest glass transition point and melting | fusing point of the polymer resin contained in a conductive polymer layer, a graphite layer, and a silver conductive resin layer.

  Polymer resin is polystyrene, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyamide, polyimide, polyamideimide, polyester, polyether, polyethylene terephthalate, polycarbonate, polyphenylene oxide , Polyurethane, polyacetal, diallyl phthalate, polyacrylate, polymethacrylate, polyacrylonitrile, polytetrafluoroethylene, polybutadiene, polyisoprene, polysiloxane, polycarbonate, cellulose, methylcellulose, ethylcellulose, fluororesin, urea resin, silicon resin, Phenol resin, melamine resin, epoxy resin, acrylic resin, alkyd resin, butyral Butter, silicone resin, be selected from polylactic acid preferred.

  It is preferable to mix erythritol and pentaerythritol into the aqueous dispersion of the conductive polymer because the aggregated conductive polymer is finely dispersed.

  Since erythritol has higher crystallinity than polyhydric alcohols such as sorbitol and maltose, it is preferable from the viewpoint of low hygroscopicity and easy handling.

  In addition, erythritol is known as a food additive used as a sweetener, and is excellent in safety and stability, and in terms of solubility in water, for example, compared to non-aqueous solvents such as ethylene glycol and glycerin. In addition, there is an advantage that the degree of freedom in design of the addition amount is high several times.

  In particular, pentaerythritol has a characteristic that it gradually sublimes when heated, and dehydrates and polymerizes when heated above its melting point. This has the advantage that the physical properties of the organic material change, and the density and strength are improved. Such reactivity is attributed to its chemical structure, and is unlikely to occur with chemical structures such as erythritol and sorbitol.

  The addition amount of erythritol and pentaerythritol is preferably 0.01 to 10% by mass because finely dispersed aggregated conductive polymer is dispersed.

  Heat treatment at a temperature equal to or higher than the melting point of erythritol and pentaerythritol is preferable because erythritol and pentaerythritol contained in the conductive polymer layer are melted and sublimated, and the electrical resistance of the conductive polymer layer is reduced.

  The solid electrolyte layer 4 includes a first conductive polymer layer 4A formed on the surface of the dielectric layer 2 and a second conductive polymer formed on the surface of the first conductive polymer layer 4A. It is good also as a 2 layer structure of the layer 4B.

  The cathode conductor 5 is not particularly limited as long as it is a conductor, but may have a two-layer structure including a carbon layer 5A such as graphite and a silver conductive resin 5B.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.

  Hereinafter, the embodiment of the present invention will be described in detail with reference to FIG. 1 used in the embodiment and Table 1 described later.

Example 1
First, a sintered body made of fine tantalum powder was formed as a valve metal.

  This sintered body was anodized at a voltage of 100 V to form a dielectric layer having a thickness of 0.13 μm. When the pore distribution measurement was performed on the sintered body after anodization by mercury porosimetry, the average pore diameter was 300 nm.

  Next, this sintered body was impregnated with an aqueous dispersion of a conductive polymer compound for 5 minutes, dried at room temperature for 30 minutes, and dried at 85 ° C. for 10 minutes. As the aqueous dispersion of the conductive polymer compound, a commercially available polyethylenedioxythiophene / polystyrenesulfonic acid aqueous solution diluted was used. The particle diameter of the conductive polymer compound in this dispersed aqueous solution is a distribution in the range of 20 to 120 nm, and the average particle diameter is 75 nm. The content of the conductive polymer compound was 0.5% by mass.

  After impregnating the conductive polymer compound in the dispersion aqueous solution and drying each time 10 times, the conductive polymer compound was dried at 180 ° C. for 30 minutes to form the first conductive polymer layer 4A. Then, after impregnating for 5 seconds with a polyethylene dioxythiophene / polystyrene sulfonic acid aqueous solution (conducting polymer content 2.0%, average particle diameter 75 nm) commercially available on the first conductive polymer layer 4A, After drying at room temperature for 30 minutes and then drying at 85 ° C. for 30 minutes, each was performed three times, and further dried at 180 ° C. for 30 minutes to form a second conductive polymer layer 4B. Next, a graphite layer 5A containing a polyester resin and a silver conductive resin layer 5B containing an acrylic resin were formed thereon to produce three solid electrolytic capacitor elements.

  Here, the differential scanning calorimetry (DSC) of the substance obtained by removing the solvent from the aqueous dispersion of the conductive polymer compound used in Example 1 was performed, and the glass transition temperature (Tg) was measured. ° C. In addition, the polymer resin contained in the graphite layer 5A and the silver conductive resin layer 5B has a glass transition temperature of 140 to 260 ° C.

  Thereafter, heat treatment was performed at 270 ° C. for 30 seconds with respect to the elements of the produced solid electrolytic capacitor.

  The dimensions of the solid electrolytic capacitor element (cathode conductor outer shape) are 1.5 mm in length, 1.0 mm in width, and 2.0 mm in thickness. Moreover, since it was judged that the solid electrolytic capacitor as a product can be produced without any particular problem, the evaluation was made on the characteristics of the capacitor element.

  Next, the electrical characteristics of the device were evaluated using an LCR meter. Table 1 shows the ESR at the measurement frequency of 100 kHz, the capacity appearance rate at the measurement frequency of 120 Hz, and the withstand voltage characteristics of the element of the solid electrolytic capacitor.

ESR converted the surface area of all cathode conductors into unit area (1 mm ² ).

  The capacity appearance rate was based on WetCap (120 Hz electrostatic capacity in a 30% sulfuric acid aqueous solution) of a sintered compact of tantalum fine powder.

The withstand voltage characteristic can be measured by sweeping the voltage at a speed of 1 V / 1 min and reading the current value at that time, and when the oxide film is broken, a rapid current rise appears. From Table 1, the time required to form a conductive polymer layer (solid electrolyte layer 4) having an ESR of 0.8 Ω / mm ² , a capacity appearance rate of 70%, and a withstand voltage characteristic of 100 V or more is 10 hours. Met.

(Example 2)
Using a dispersion solution of a conductive polymer compound with 0.01% by mass of erythritol used, and after forming the silver conductive resin layer 5B, the element of the solid electrolytic capacitor was heated at 270 ° C. for 30 seconds. Except for this, a capacitor element was produced in the same manner as in Example 1, and electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 0.4 mΩ / mm ² , a capacity appearance rate of 79%, and a withstand voltage characteristic of 100 V or more was similar to that of Example 1. . The erythritol used has a melting point of 120 ° C.

(Example 3)
Using a dispersion solution of a conductive polymer compound to which 5.0% by mass of erythritol was added, and after forming the silver conductive resin layer 5B, the solid electrolytic capacitor element was heated at 270 ° C. for 30 seconds. A capacitor element was produced in the same manner as in Example 1 except that the evaluation was performed, and electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 0.3 Ω / mm ² , a capacity appearance rate of 79%, and a withstand voltage characteristic of 100 V or more was similar to that in Example 1. . The erythritol used has a melting point of 120 ° C. as in Example 2.

Example 4
The solid electrolytic capacitor element was subjected to heat treatment at 270 ° C. for 30 seconds after using a dispersion solution of conductive polymer compound with 10.0% by mass of erythritol added and after forming silver conductive resin layer 5B. Except for the above, a capacitor element was produced in the same manner as in Example 1, and the electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 0.1 Ω / mm ² , a capacity appearance rate of 89%, and a withstand voltage characteristic of 100 V or more was similar to that in Example 1. . The erythritol used has a melting point of 120 ° C. as in Example 2.

(Example 5)
Other than using a dispersion of conductive polymer compound in which 15% by mass of erythritol is added and forming a silver conductive resin layer 5B, the element of the solid electrolytic capacitor is subjected to heat treatment at 270 ° C. for 30 seconds. Produced a capacitor element in the same manner as in Example 1 and evaluated the electrical characteristics. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 0.1 Ω / mm ² , a capacity appearance rate of 89%, and a withstand voltage characteristic of 100 V or more was similar to that in Example 1. . The erythritol used has a melting point of 120 ° C. as in Example 2.

(Example 6)
Using a dispersion solution of a conductive polymer compound in which 10% by mass of erythritol and 1% by mass of pentaerythritol are added, and after forming the silver conductive resin layer 5B, a solid electrolytic capacitor element is formed at 30 ° C. at 30 ° C. A capacitor element was produced in the same manner as in Example 1 except that the heat treatment was performed for 2 seconds, and the electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 0.08 mΩ / cm ² , a capacity appearance rate of 90%, and a withstand voltage characteristic of 100 V or more was similar to that of Example 1. . The erythritol used has a melting point of 120 ° C. as in Example 2. The melting point of the used pentaerythritol is 220 ° C.

(Example 7)
Using a dispersion solution of a conductive polymer compound containing 10% by mass of erythritol and 2% by mass of pentaerythritol, and forming a silver conductive resin layer 5B, a solid electrolytic capacitor element is formed at 30 ° C. at 30 ° C. A capacitor element was produced in the same manner as in Example 1 except that the heat treatment was performed for 2 seconds, and the electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 0.05 mΩ / cm ² , a capacity appearance rate of 92%, and a withstand voltage characteristic of 100 V or more was similar to that of Example 1. . The melting point of the erythritol used is the same as in Example 2, and the melting point of pentaerythritol is the same as in Example 6.

(Example 8)
For the element of the solid electrolytic capacitor after using the dispersion of the conductive polymer compound added with 10% by mass of erythritol and 3% by mass of pentaerythritol, and after forming the silver conductive resin layer 5B. A capacitor element was produced in the same manner as in Example 1 except that heat treatment was performed at 270 ° C. for 30 seconds, and electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 0.3 mΩ / cm ² , a capacity appearance rate of 79%, and a withstand voltage characteristic of 100 V or more was comparable to that of Example 1. . The melting point of the used erythritol is the same as that of Example 2, and the melting point of pentaerythritol is the same as that of Example 6.

Example 9
The element of the solid electrolytic capacitor was heat-treated at 270 ° C. for 30 seconds after using a dispersion solution of the conductive polymer compound added with 2% by mass of pentaerythritol and forming the silver conductive resin layer 5B. Except for the above, capacitor elements were produced in the same manner as in Example 1, and electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 0.4 mΩ / cm ² , a capacity appearance rate of 79%, and a withstand voltage characteristic of 100 V or more was similar to that of Example 1. . The melting point of the pentaerythritol used is the same as in Example 6.

(Example 10)
Capacitor in the same manner as in Example 1 except that the sintered body has an average pore diameter of 200 nm and the solid conductive capacitor element 5B is heated at 270 ° C. for 30 seconds after the formation of the silver conductive resin layer 5B. Were fabricated and the electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 1.8 Ω / mm ² , a capacity appearance rate of 51%, and a withstand voltage characteristic of 100 V or more was similar to that in Example 1. .

(Example 11)
Capacitor in the same manner as in Example 1 except that the average pore diameter of the sintered body was 50 nm and the element of the solid electrolytic capacitor was heat-treated at 270 ° C. for 30 seconds after forming the silver conductive resin layer 5B. The electrical characteristics were evaluated. From Table 1, the ESR was 2000Ω / mm ² , the capacity appearance rate was 5.0%, and the withstand voltage characteristic was not measured because it was not applicable as a capacitor. The time required to form the solid electrolyte layer 4 was the same as in Example 1.

(Example 12)
Solid electrolysis after the formation of the first conductive polymer layer 4A using the ethylenedioxythiophene / polystyrene sulfonic acid aqueous solution having a conductive polymer content of 0.1% and the formation of the silver conductive resin layer 5B A capacitor element was produced in the same manner as in Example 1 except that the capacitor element was heat-treated at 270 ° C. for 30 seconds, and the electrical characteristics were evaluated. From Table 1, the ESR was 4.8 Ω / mm ² , the capacity appearance rate was 59%, and the withstand voltage characteristic was 100 V or more. The time required to form the solid electrolyte layer 4 was the same as in Example 1.

(Example 13)
Solid electrolysis after the formation of the first conductive polymer layer 4A using the ethylenedioxythiophene / polystyrenesulfonic acid aqueous solution having a conductive polymer content of 1.0% and the formation of the silver conductive resin layer 5B A capacitor element was produced in the same manner as in Example 1 except that the capacitor element was heat-treated at 270 ° C. for 30 seconds, and the electrical characteristics were evaluated. From Table 1, ESR was 1.0 Ω / mm ² , the capacity appearance rate was 67%, and the withstand voltage characteristic was 100 V or more. The time required to form the solid electrolyte layer 4 was the same as in Example 1.

(Example 14)
Solid electrolysis after the formation of the first conductive polymer layer 4A using the ethylenedioxythiophene / polystyrene sulfonic acid aqueous solution having a conductive polymer content of 10.0% and the formation of the silver conductive resin layer 5B A capacitor element was produced in the same manner as in Example 1 except that the capacitor element was heat-treated at 270 ° C. for 30 seconds, and the electrical characteristics were evaluated. From Table 1, ESR was 10 Ω / mm ² , the capacity appearance rate was 55%, and the withstand voltage characteristic was 100 V or more. The time required to form the solid electrolyte layer 4 was the same as in Example 1.

(Example 15)
Solid electrolysis after the formation of the first conductive polymer layer 4A using the ethylenedioxythiophene / polystyrene sulfonic acid aqueous solution having a conductive polymer content of 11.0% and the formation of the silver conductive resin layer 5B A capacitor element was produced in the same manner as in Example 1 except that the capacitor element was heat-treated at 270 ° C. for 30 seconds, and the electrical characteristics were evaluated. From Table 1, the ESR was 50 Ω / mm ² , the capacity appearance rate was 54%, and the withstand voltage characteristic was 100 V or more. The time required to form the solid electrolyte layer 4 was the same as in Example 1.

(Comparative Example 1)
As Comparative Example 1, a capacitor element was produced in the same manner as in Example 1 except that the solid electrolytic capacitor element was not subjected to heat treatment after the silver conductive resin layer 5B was formed, and electrical characteristics were evaluated. From Table 1, the time required to form the solid electrolyte layer 4 having an ESR of 1 Ω / mm ² , a capacity appearance rate of 65%, and a withstand voltage characteristic of 100 V or more was comparable to that in Example 1.

(Comparative Example 2)
As Comparative Example 2, capacitor characteristics when the solid electrolyte layer 4 is formed by chemical oxidative polymerization are shown. After impregnating each of the aqueous solution containing the monomer and the aqueous solution containing the oxidizing agent, room temperature drying, acid washing, and high temperature drying were repeated three times to form the first conductive polymer layer 4A.

Next, a polyethylene dioxythiophene / polystyrene sulfonic acid aqueous solution commercially available on the first conductive polymer layer 4A (conducting polymer content 2.0 mass%, particle size 20 to 120 nm, average particle size 75 nm). After being impregnated for 5 seconds, it was dried at room temperature for 30 minutes, further dried at 85 ° C. for 30 minutes, and then dried at 180 ° C. for 30 minutes to form the first conductive polymer layer 4B. From Table 1, the ESR was 0.1Ω / mm ² , the capacity appearance rate was 95%, and the withstand voltage characteristic was 50V. The time required for forming the solid electrolyte layer 4 was 30 hours.

  In Example 1 and Comparative Example 1, the presence or absence of heat treatment was compared. It can be seen that the ESR and the capacity appearance rate can be improved by heating the anode conductor 1.

The difference in average pore diameter after anodization of the sintered bodies was compared between Example 1, Example 10, and Example 11. When the average pore diameter is 300 nm, 200 nm, and 50 nm, the ESR is 0.8 mΩ / cm ² , 1.8 mΩ / cm ² , 2000 mΩ / cm ² , and the capacity appearance rate is 70%, 51%, and 5.0%. In the case of an average pore diameter of 300 nm, excellent characteristics were obtained. From this result, it has been found that the size of the pore diameter of the porous metal of the valve metal with respect to the particle diameter of the conductive polymer compound is important.

  By Example 1 and Examples 12-15, the influence of the conductive polymer content in the aqueous dispersion of the conductive polymer compound was compared. Inclusion of a conductive polymer in the aqueous dispersion improves the ESR and capacity appearance rate. When the conductive polymer content is changed from 0.1% by mass to 10% by mass, the ESR and capacity appearance rate also change. It was found that a peak was obtained at 0.5% by mass to 1.0% by mass.

  According to Examples 2 to 5, when the amount of erythritol added is 0.01% by mass to 10% by mass, an effect of improving ESR reduction and coverage is obtained, and when the amount added is 10% by mass, excellent characteristics are obtained. It was. It was found that the characteristics were equivalent at the addition amounts of 10% by mass and 15% by mass, and the addition effect was saturated at 10% by mass.

  According to Examples 6 to 8, when the addition amount of erythritol is 10% by mass and the addition amount of pentaerythritol is 1.0% to 3.0% by mass, the effect of improving ESR reduction and coverage is obtained, and the addition amount is 2 In the case of 0.0 mass%, excellent characteristics were obtained.

  According to Example 9, when the added amount of pentaerythritol was 2.0% by mass, an effect of reducing ESR and improving the coverage was obtained.

  When Example 4, Example 7, and Example 9 are compared, when erythritol and pentaerythritol are added in a mixed manner, erythritol and pentaerythritol have a greater effect of reducing ESR and covering rate than when erythritol and pentaerythritol are added alone. I understood.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to these embodiments, and the present invention is not limited to the scope of the present invention. Included in the invention. That is, various changes and modifications that can be naturally made by those skilled in the art are also included in the present invention.

1 Anode conductor
2 Dielectric layer
3 holes
4 Solid electrolyte layer
4A First conductive polymer layer
4B Second conductive polymer layer
5 Cathode conductor
5A Graphite layer
5B Silver conductive resin layer

Claims (12)

  A step of forming a dielectric layer on the surface of an anode conductor made of a valve-acting metal powder; and a solid electrolyte layer by impregnating or applying a dispersion aqueous solution of a conductive polymer compound on the surface of the dielectric layer and drying Forming a conductive polymer layer constituting the conductive layer, and forming a graphite layer and a silver conductive resin layer as a cathode conductor on the surface of the conductive polymer layer, and then performing a heat treatment. A method for producing a solid electrolytic capacitor.   The heat treatment temperature is equal to or higher than a highest temperature among a glass transition temperature and a melting point of a polymer resin contained in the conductive polymer layer, the graphite layer, and the silver conductive resin layer. 2. A method for producing a solid electrolytic capacitor according to 1.   3. The solid electrolytic capacitor according to claim 1, wherein the average pore diameter of the anode conductor is 2.5 to 15 times the average particle diameter of the aqueous dispersion of the conductive polymer compound. Manufacturing method.   The method for producing a solid electrolytic capacitor according to any one of claims 1 to 3, wherein the conductive polymer content of the aqueous dispersion of the conductive polymer compound is 0.1 to 10% by mass. .   5. The method according to claim 1, further comprising a step of performing a heat treatment at a temperature equal to or higher than a melting point of the polyhydric alcohol when the aqueous dispersion of the conductive polymer compound further includes a polyhydric alcohol. The manufacturing method of the solid electrolytic capacitor of description.   6. The method for producing a solid electrolytic capacitor according to claim 1, wherein a content of the polyhydric alcohol is 0.01 to 10% by mass.   The polymer resin is polystyrene, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyamide, polyimide, polyamideimide, polyester, polyether, polyethylene terephthalate, polycarbonate, polyphenylene. Oxide, polyurethane, polyacetal, diallyl phthalate, polyacrylate, polymethacrylate, polyacrylonitrile, polytetrafluoroethylene, polybutadiene, polyisoprene, polysiloxane, polycarbonate, cellulose, methylcellulose, ethylcellulose, fluororesin, urea resin, silicon resin , Phenolic resin, melamine resin, epoxy resin, acrylic resin, alkyd resin, butyrate Le resin is at least one selected silicone resin, a polylactic acid, a solid electrolytic capacitor manufactured by the manufacturing method of a solid electrolytic capacitor according to any one of claims 2 to 6.   The solid electrolytic capacitor according to claim 7, wherein the conductive polymer layer contains a polyhydric alcohol.   The solid electrolytic capacitor according to claim 7 or 8, wherein the polyhydric alcohol is at least one selected from erythritol and pentaerythritol.   10. The solid electrolytic capacitor according to claim 7, wherein the conductive polymer layer includes a polymer and a polyacid made of 3,4-ethylenedioxythiophene and derivatives thereof. 10.   The solid electrolytic capacitor according to claim 10, wherein the polyacid is polystyrene sulfonic acid.   The solid electrolytic capacitor according to claim 7, wherein the valve metal is at least one selected from aluminum, tantalum, and niobium.

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