JP2012134369A - Solid electrolytic capacitor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor having excellent heat resistance and conductivity.SOLUTION: A solid electrolytic capacitor comprises an anode body having a dielectric film on the surface, and a conductive polymer layer provided on the anode body. A dopant and a 12CaO-7AlOcompound are contained in the conductive polymer layer.

Description

  The present invention relates to a solid electrolytic capacitor and a method for manufacturing the solid electrolytic capacitor, and more particularly to a solid electrolytic capacitor including a conductive polymer layer and a method for manufacturing the solid electrolytic capacitor.

  In recent years, solid state capacitors having a conductive polymer layer having a conductive skeleton such as polypyrrole, polythiophene, polyfuran, and polyaniline as a basic skeleton are widely known. A solid electrolytic capacitor having a high electrical conductivity of the conductive polymer layer and a low equivalent series resistance (hereinafter referred to as “ESR”) can be manufactured. As a method for forming such a conductive polymer layer, a chemical polymerization method or an electrolytic polymerization method is generally used.

  The chemical polymerization method is, for example, a method of forming a conductive polymer layer on a dielectric coating by reacting a conductive polymer precursor monomer constituting the conductive polymer layer with an oxidizing agent. Electropolymerization is a method in which an anode body provided with a dielectric film is immersed in an electrolyte solution containing a precursor monomer, and an electroconductive polymer layer is formed on the dielectric film by utilizing an oxidation reaction that occurs at the anode. It is a method of forming.

  In any of the chemical polymerization method and the electrolytic polymerization method, a dopant is added to the reaction system of the precursor monomer in order to impart conductivity to the polymer constituted by polymerization of the precursor monomer. That is, the conductive polymer layer formed by the chemical polymerization method or the electrolytic polymerization method has a structure in which a dopant is doped in a structure made of a polymer serving as a basic skeleton.

  Due to the above structure of the conductive polymer layer, for example, when a solid electrolytic capacitor is placed in a high-temperature environment, radicals are generated from the dopant present in the conductive polymer layer, and conductive due to the radical reaction caused by this. The entire conductive polymer layer may be radically oxidized. Moreover, the generation of radicals and the progress of radical oxidation also occur due to the surplus oxidant remaining in the conductive polymer layer. Since the conductivity of the conductive polymer layer is lowered by radical oxidation of the conductive polymer layer, the performance of the solid electrolytic capacitor is lowered as a result.

  Corresponding to this, Patent Document 1 discloses a technique of adding a phenolic compound used as an antioxidant to a reaction system as an antioxidant when forming a conductive polymer layer by a chemical polymerization method. It is disclosed. Patent Document 2 discloses a technique in which a formed conductive polymer layer is impregnated with a phenol compound as an antioxidant. According to these techniques, an antioxidant can be included in the conductive polymer layer, whereby generation or progress of radical oxidation in the conductive polymer layer can be suppressed.

JP 2003-147055 A JP-A-8-78292

  However, regarding the techniques of Patent Documents 1 and 2, while the heat resistance of the solid electrolytic capacitor can be improved, the antioxidant used is a phenolic compound having a high electrical resistance, and therefore includes the antioxidant. The conductive polymer layer has a large resistance, resulting in a problem that the ESR of the solid electrolytic capacitor increases.

  Patent Document 2 describes that an antioxidant is present only in the vicinity of the surface of the conductive polymer layer in order to suppress an increase in electrical resistance due to the presence of the antioxidant. However, since the generation position of radicals in the conductive polymer layer is not limited to the vicinity of the surface, such a configuration cannot sufficiently suppress the occurrence or progress of radical oxidation in the conductive polymer layer.

  In view of the above circumstances, an object of the present invention is to provide a solid electrolytic capacitor excellent in heat resistance and conductivity and a method for manufacturing the same.

A first aspect of the present invention includes an anode body having a dielectric coating on a surface thereof, and a conductive polymer layer provided on the anode body. In the conductive polymer layer, a dopant and 12CaO · A solid electrolytic capacitor containing a 7Al ₂ O ₃ compound.

  In the solid electrolytic capacitor, the conductive polymer layer is preferably formed by a chemical polymerization method.

  In the solid electrolytic capacitor, the conductive polymer layer preferably contains an oxidizing agent used for the chemical polymerization method.

In the solid electrolytic capacitor, the conductive polymer layer uses a mixed liquid containing a precursor monomer, a dopant, an oxidant, and a 12CaO · 7Al ₂ O ₃ compound constituting the conductive polymer layer. The content of the 12CaO · 7Al ₂ O ₃ compound with respect to the dopant is preferably 0.01 mol% or more and 0.1 mol% or less in the mixed solution.

A second aspect of the present invention is a method for producing a solid electrolytic capacitor having a conductive polymer layer, comprising the step of forming a conductive polymer layer on an anode body having a dielectric coating on the surface. In the step of forming the conductive polymer layer, the precursor monomer of the conductive polymer constituting the conductive polymer layer is polymerized by a chemical polymerization method in the presence of a dopant and a 12CaO · 7Al ₂ O ₃ compound. It is preferable to form a conductive polymer layer containing a dopant and a 12CaO · 7Al ₂ O ₃ compound.

In the method for producing a solid electrolytic capacitor, in the step of forming the conductive polymer layer, the conductive polymer layer is formed using a mixed solution containing an oxidizing agent, a precursor monomer, a dopant, and a 12CaO · 7Al ₂ O ₃ compound. Is preferably formed.

In the method for manufacturing the solid electrolytic capacitor, in a mixed solution, it is preferable that the content of 12CaO · 7Al ₂ O ₃ compound is less 0.1 mol% or more 0.01 mol% with respect to the dopant.

  According to the present invention, it is possible to provide a solid electrolytic capacitor excellent in heat resistance and conductivity and a method for manufacturing the same.

It is typical sectional drawing of the solid electrolytic capacitor of embodiment. It is the schematic for demonstrating the structure of the capacitor | condenser element of FIG. It is typical sectional drawing which shows the structure between the anode body and separator in a capacitor | condenser element.

  Embodiments of a solid electrolytic capacitor according to the present invention will be described below with reference to the drawings. The following embodiments are merely examples, and various embodiments can be implemented within the scope of the present invention. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Solid electrolytic capacitor>
First, the solid electrolytic capacitor according to the embodiment will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of the solid electrolytic capacitor of the embodiment, FIG. 2 is a schematic view for explaining the configuration of the capacitor element of FIG. 1, and FIG. 3 is an anode body in the capacitor element. It is typical sectional drawing which shows the structure between a separator.

  In FIG. 1, the solid electrolytic capacitor includes a capacitor element 10, a bottomed case 11, a sealing member 12, a seat plate 13, lead wires 14A and 14B, and lead tabs 15A and 15B. Lead tabs 15A and 15B are connected to the capacitor element 10, and lead wires 14A and 14B are electrically connected to the lead tabs 15A and 15B, respectively. The capacitor element 10 is housed in a bottomed case 11 having an open end on the upper surface, and a sealing member 12 formed so that the lead wires 14A and 14B penetrate is disposed on the upper surface of the capacitor element 10. Thus, the bottomed case 11 is sealed. Further, the vicinity of the open end of the bottomed case 11 is curled by being laterally drawn, and a seat plate 13 is disposed in the processed curled portion.

  2, the capacitor element 10 includes an anode body 21 connected to the lead tab 15A, a cathode body 22 connected to the lead tab 15B, and a separator 23. The anode body 21 and the cathode body 22 are integrally wound via a separator 23, and the outermost periphery of the wound body is stopped by a winding stop tape 24. In addition, in FIG. 2, the state before stopping the outermost periphery of a wound body is shown.

  As shown in FIG. 3, the anode body 21 includes a metal foil 30 having a roughened surface and a dielectric coating 31 provided on the surface of the metal foil 30. A conductive polymer layer 32 is provided between the anode body 21 and the separator 23. In this specification, the wound body in which the conductive polymer layer 32 is formed between the anode body 21 and the separator 23 is the capacitor element 10. Needless to say, a conductive polymer layer is also provided between the separator 23 and the cathode body 22.

  The metal foil 30 constituting the anode body 21 is not particularly limited, and for example, a metal foil made of a valve metal such as aluminum, tantalum, or niobium can be used. The dielectric coating 31 can be formed, for example, by subjecting the surface of the anode body 21 to an etching process for roughening and then subjecting the surface of the roughened foil to a chemical conversion treatment. A dielectric coating may be laminated on the anode body 21.

  The cathode body 22 is not particularly limited, and for example, a metal foil made of a valve action metal such as aluminum, tantalum, or niobium can be used. The metal constituting the anode body 21 and the cathode body 22 may be the same or different.

  The separator 23 is not particularly limited, and for example, a nonwoven fabric mainly composed of synthetic cellulose, polyethylene terephthalate, vinylon, or aramid fiber can be used.

  The conductive polymer constituting the conductive polymer layer 32 is made of polypyrrole, polythiophene, polyfuran, polyaniline, or a derivative thereof. Because of the high conductivity of polythiophene and its derivatives, it is preferable to use a conductive polymer made of polythiophene or its derivatives, and polyethylene dioxythiophene is particularly preferable.

The conductive polymer layer 32 includes a dopant and a 12CaO.7Al ₂ O ₃ compound (hereinafter referred to as “C12A7 compound”).

  The dopant is not particularly limited, and sulfonic acid compounds such as alkylsulfonic acid, aromatic sulfonic acid and polycyclic aromatic sulfonic acid, nitric acid, sulfuric acid and the like can be used. When alkylsulfonic acid is used as the dopant, for example, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid and the like can be suitably used. When aromatic sulfonic acid is used as the dopant, for example, p-toluenesulfonic acid, methoxybenzenesulfonic acid, dodecylbenzenesulfonic acid and the like can be suitably used. When polycyclic aromatic sulfonic acid is used as the dopant, for example, naphthalene sulfonic acid, tetralin sulfonic acid and the like can be suitably used. Among these, p-toluenesulfonic acid is particularly preferable because it can impart high conductivity to the conductive polymer layer 32.

The C12A7 compound is an inorganic compound containing electrons in the gaps in the crystal structure, and has high conductivity and antioxidant properties. Among these, since the C12A7 compound containing electrons of 2 × 10 ¹⁸ cm ⁻³ or more and less than 2.3 × 10 ²¹ cm ⁻³ has high antioxidant properties (see, for example, JP 2009-161728 A), it is more preferable. Can be used.

  The bottomed case 11 is not particularly limited, and for example, a case made of a metal such as aluminum, stainless steel, copper, iron, brass, or an alloy thereof can be used. Moreover, the sealing member 12 will not be specifically limited if it is an insulating substance. For example, an insulating elastic body, in particular, insulating rubber such as silicon rubber, fluorine rubber, ethylene propylene rubber, high pylon rubber, butyl rubber, and isoprene rubber, which are materials having relatively high heat resistance and sealing properties can be used. . Moreover, the material of lead wire 14A, 14B and lead tab 15A, 15B is not specifically limited, either can use a well-known material.

  According to the solid electrolytic capacitor of this embodiment, the conductive polymer layer 32 contains the dopant and the C12A7 compound. Since the C12A7 compound has conductivity and antioxidant properties, it can suppress the progress of radical reaction caused by the dopant and oxidant in the conductive polymer layer 32, and a conventional antioxidant can be used. The increase in ESR that occurs when used can be suppressed. Therefore, the solid electrolytic capacitor of this embodiment is excellent in heat resistance and conductivity.

  Further, in the solid electrolytic capacitor of the present embodiment, when the conductive polymer layer 32 is formed by a chemical polymerization method, the heat resistance and the conductivity are improved particularly with respect to the conventional solid electrolytic capacitor. Can do. The reason is as follows.

  When a conductive polymer layer is produced by a chemical polymerization method, an oxidizing agent is required in addition to the precursor monomer and the dopant in the polymerization reaction system for forming the conductive polymer layer. In the chemical polymerization method, a large amount of oxidant is generally added to the polymerization reaction system in order to increase the polymerization rate of the precursor monomer. In the chemical polymerization method, a salt composed of a metal having an oxidizing agent function and a sulfonic acid compound having a dopant function (hereinafter referred to as “sulfone metal acid salt”) is obtained because of the good yield of the conductive polymer. ) Is widely used.

  Based on the above points, assuming that the chemical polymerization method is performed using a ferric sulfonic acid salt that has both the function of an oxidant and the function of a dopant, in the chemical polymerization method, the mixture is a polymerization reaction system. The molar amount of the ferric sulfonic acid salt to be added is higher than the molar amount of the sulfonic acid compound as a dopant added to the electrolytic solution as a reaction system in the electrolytic polymerization method. In this case, in the polymerization reaction system of the chemical polymerization method, iron ions as oxidants and sulfonate ions as dopants are excessively present.

  That is, the conductive polymer layer formed by the chemical polymerization method has more dopants and more oxidizer than the conductive polymer layer formed by electrolytic polymerization. . Most of the iron ions and sulfonate ions present in excess in the polymerization reaction system are taken into the conductive polymer layer and cause radical reactions in the conductive polymer layer. The formed conductive polymer layer tends to cause radical reaction and tends to have low heat resistance. Therefore, as described above, when the conductive polymer layer 32 is formed by the chemical polymerization method, the effect of the C12A7 compound can be exhibited particularly.

In the solid electrolytic capacitor of the present embodiment, when the conductive polymer layer 32 is formed by a chemical polymerization method, the chemical polymerization method includes a precursor monomer, a dopant, an oxidizing agent, and a C12A7 compound. A mixed solution can be used. The present inventor has intensively studied, particularly when the content of the 12CaO · 7Al ₂ O ₃ compound with respect to the dopant is 0.01 mol% or more and 0.1 mol% or less in the mixed solution, It has been found that the heat resistance and conductivity characteristics of the resin are improved. Furthermore, the content of the C12A7 compound in the mixed solution is preferably 0.03 mol% or more with respect to the dopant.

  The winding type solid electrolytic capacitor shown in FIG. 1 has been described above. However, the solid electrolytic capacitor of the present invention is not limited to this. For example, a conductive polymer layer is formed on an anode body made of a sintered body. It also includes a solid electrolytic capacitor having a structure provided, and a solid electrolytic capacitor having a structure including a conductive polymer layer on an anode body made of a metal plate.

<Method for manufacturing solid electrolytic capacitor>
Hereinafter, an example of a method for manufacturing the solid electrolytic capacitor according to the present embodiment will be described with reference to FIGS. In addition, although the manufacturing method of the solid electrolytic capacitor of FIG. 1 is demonstrated as an example below, processes other than the process of forming a conductive polymer layer are well-known techniques.

(Process for preparing anode body)
In this step, an anode body 21 provided with a dielectric coating 31 is prepared (see FIG. 2).

  Specifically, first, the surface of the metal foil 30 cut into a predetermined size is roughened. The type of metal is not particularly limited, but it is preferable to use a valve metal such as aluminum, tantalum, or niobium from the viewpoint that the dielectric coating 31 can be easily formed. The roughening means that a plurality of recesses are provided on the surface of the metal foil 30. For example, a plurality of recesses can be formed on the surface of the metal foil 30 by etching the metal foil 30. .

  Next, the dielectric coating 31 is formed on the surface of the roughened metal foil 30. The method for forming the dielectric film 31 is not particularly limited. For example, when the metal foil 30 is made of a valve metal, the surface of the metal foil 30 is changed to the dielectric film 31 by chemical conversion of the metal foil 30. be able to. The chemical conversion treatment is a method in which the anode body 21 is immersed in a chemical conversion solution such as an ammonium adipate solution or a phosphoric acid aqueous solution and heat treated, or a method in which the anode body 21 is immersed in the chemical conversion solution and a voltage is applied. is there.

  By this step, as shown in FIG. 3, the anode body 21 having the dielectric coating 31 provided on the metal foil 30 having a concave portion on the surface is formed. Usually, from the viewpoint of mass productivity, roughening treatment and chemical conversion treatment are performed on a large-sized valve action metal foil. Therefore, in this case, the anode body 21 can be prepared by cutting the treated metal foil into a desired size.

(Process for producing a wound body)
Next, in this step, a wound body is manufactured using the anode body 21.

  Specifically, first, the anode body 21 and the cathode body 22 are wound through the separator 23. At this time, by winding the lead tabs 15A and 15B while winding them, the lead tabs 15A and 15B can be erected in the wound body as shown in FIG.

  And among the wound anode body 21, cathode body 22, and separator 23, the winding tape 24 is disposed on the outer surface of the cathode body 22 located in the outermost layer, and the end of the cathode body 22 is secured to the winding tape. A winding is produced by stopping at 24. When the anode body 21 is prepared by cutting a large metal foil, a chemical conversion treatment may be further performed on the wound body in order to provide a dielectric coating on the cut surface of the anode body 21. .

  The cathode body 22 is made of, for example, a metal foil cut to the same size as the anode body 21. The type of metal is not particularly limited, and for example, a valve metal such as aluminum, tantalum, or niobium can be used. Further, the surface of the cathode body 22 may be subjected to chemical conversion treatment similarly to the anode body 21. In addition, the anode body 21 and the cathode body 22 may be one each, and may be multiple sheets.

  Moreover, the material of the separator 23 is not specifically limited, For example, the nonwoven fabric etc. which have a synthetic cellulose, a polyethylene terephthalate, a vinylon, an aramid fiber as a main component can be used. The materials of the lead wires 14A and 14B and the lead tabs 15A and 15B are not particularly limited as long as they can conduct electricity.

(Process of forming a conductive polymer layer)
Next, in this step, the conductive polymer layer 32 is formed on the anode body 21. In this step, the conductive polymer precursor monomer constituting the conductive polymer layer 32 is polymerized by a chemical polymerization method in the presence of the dopant and the C12A7 compound, and the conductive polymer layer 32 contains the dopant and the C12A7 compound. A molecular layer 32 is formed.

  Specifically, first, a mixed solution used for chemical polymerization is prepared. The mixed solution is prepared by adding an oxidant, a precursor monomer, a dopant, and a C12A7 compound to a solvent and mixing them.

  Next, after the produced wound body is immersed in the mixed solution, the wound body is pulled up and allowed to stand for a predetermined time. Thereby, in the liquid mixture adhering to the surface of the anode body 21, the polymerization reaction of the precursor monomer due to the function of the oxidizing agent occurs in the presence of the dopant and the C12A7 compound, and the conductive high in which the dopant and the C12A7 compound are contained. A molecular layer 32 is formed. Further, the oxidizing agent is simultaneously taken into the conductive polymer layer 32, and the solvent is removed by evaporation.

  The precursor monomer is a compound that becomes polypyrrole, polythiophene, polyfuran, polyaniline, or a derivative thereof by polymerization. For example, 3,4-ethylenedioxythiophene, 3-alkylthiophene, N-methylpyrrole, N, N-dimethylaniline, N-alkylaniline and the like can be used as the precursor monomer. In particular, 3,4-ethylenedioxythiophene, which is one of polythiophene precursor monomers, is preferred. In this case, the conductive polymer layer 32 having particularly high conductivity can be formed.

  The oxidizing agent only needs to be able to polymerize the precursor monomer. For example, sulfuric acid, hydrogen peroxide, iron (III), copper (II), chromium (VI), cerium (IV), manganese (VII), zinc ( II) and the like can be used. Especially, it is preferable to use the sulfonic acid metal salt which comprised these metals and salts. Since the sulfonic acid metal salt is composed of a sulfonic acid compound having a function as a dopant and a metal having a function as an oxidizing agent as described above, the sulfonic acid metal salt also serves as a dopant and an oxidizing agent. Can do. Specifically, naphthalene sulfonic acid metal salt, tetralin sulfonic acid metal salt, alkylbenzene sulfonic acid metal salt, alkoxybenzene sulfonic acid metal salt, and the like can be used, among which p-toluenesulfonic acid metal salt is used. be able to. Especially, p-toluenesulfonic acid ferric acid has high both functionality, and can be used suitably.

  As the solvent, it is preferable to use a solvent having high dispersibility of the precursor monomer and the C12A7 compound and high solubility of the oxidizing agent and the dopant. For example, alcohols such as butanol, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol can be suitably used.

  In the mixed solution, the content of the C12A7 compound with respect to the dopant is preferably 0.01 mol% or more and 0.1 mol% or less. For example, when 1 mol of the dopant is contained in the mixed solution, the C12A7 compound is preferably contained in the mixed solution in an amount of 0.01 mol to 0.1 mol. Moreover, it is more preferable that content of the C12A7 compound with respect to a dopant is 0.03 mol% or more in a liquid mixture. In this case, the heat resistance and conductivity characteristics of the formed conductive polymer layer 32 can be improved.

  Here, a precursor monomer, an oxidizing agent, a dopant and a C12A7 compound are added to one mixed solution to construct a polymerization reaction system consisting of one liquid, but a polymerization reaction system consisting of two liquids may be constructed. . For example, you may use the 1st liquid which consists of a liquid precursor monomer, and the 2nd liquid which adds a dopant, an oxidizing agent, and a C12A7 compound to a solvent. In this case, the precursor monomer, the oxidizing agent, the dopant, and the C12A7 compound can be attached to the anode body 21 by immersing the wound body in the first liquid and the second liquid in order.

  However, from the simplification of the formation of the conductive polymer layer 32, the high electrical conductivity of the conductive polymer layer 32, and the high yield of the conductive polymer, a polymerization reaction system comprising one liquid is used. That is, it is preferable to use the above-described mixed solution containing an oxidizing agent, a precursor monomer, a dopant, and a C12A7 compound.

  By this step, the conductive polymer layer 32 is formed on the anode body 21, and the capacitor element 10 in which the conductive polymer layer 32 is formed between the anode body 21 and the separator 23 is obtained through the above steps. Produced.

(Process of sealing the capacitor element)
Next, in this step, the capacitor element 10 is sealed.

  Specifically, first, the capacitor element 10 is accommodated in the bottomed case 11 so that the lead wires 14 </ b> A and 14 </ b> B are positioned on the upper surface where the bottomed case 11 is opened. Next, the sealing member 12 formed so that the lead wires 14 </ b> A and 14 </ b> B penetrate is disposed above the capacitor element 10, and the capacitor element 10 is sealed in the bottomed case 11.

  As a material of the bottomed case 11, a case made of a metal such as aluminum, stainless steel, copper, iron, or brass can be used, or an alloy thereof can be used. The sealing member 12 may be an insulating material. As a material of the sealing member 12, for example, an insulating elastic body, in particular, a material having a relatively high heat resistance and sealing property, such as silicon rubber, fluorine rubber, ethylene propylene rubber, hyperon rubber, butyl rubber, isoprene rubber, etc. Insulating rubber can be used.

  Next, lateral drawing and curling are performed in the vicinity of the open end of the bottomed case 11 that seals the capacitor element 10. And the solid electrolytic capacitor shown in FIG. 1 can be manufactured by arrange | positioning the seat board 13 in the processed curl part.

  According to the method for manufacturing the solid electrolytic capacitor of the present embodiment, in the step of forming the conductive polymer layer 32, the precursor monomer is polymerized by the chemical polymerization method in the presence of the dopant and the C12A7 compound. The conductive polymer layer 32 containing the C12A7 compound can be formed. Since the C12A7 compound has conductivity and antioxidant properties, it can suppress the progress of radical reaction caused by the dopant in the conductive polymer layer 32, and when a conventional antioxidant is used. Increase in ESR can be suppressed. Therefore, the manufacturing method of the solid electrolytic capacitor of this embodiment can manufacture a solid electrolytic capacitor having excellent heat resistance and conductivity.

  In the method for manufacturing the solid electrolytic capacitor of the present embodiment, since the chemical polymerization reaction system includes an oxidizing agent, the conductive polymer layer 32 includes an oxidizing agent in addition to the dopant and the C12A7 compound. include. As described above, an oxidizing agent such as iron ion causes a radical reaction in the conductive polymer layer 32 as in the case of the dopant, but the C12A7 compound exists in the conductive polymer layer 32. Therefore, a solid electrolytic capacitor having excellent heat resistance and conductivity can be manufactured.

  In the method for manufacturing a solid electrolytic capacitor of the present embodiment, it is preferable to form conductive polymer layer 32 using a mixed solution containing an oxidant, a precursor monomer, a dopant, and a C12A7 compound. In this case, the dopant and the C12A7 compound can be uniformly present in the conductive polymer layer 32. By making the dopant uniformly present in the conductive polymer layer 32, the electrical characteristics of the conductive polymer layer 32 can be improved, and by making the C12A7 compound uniformly present, the conductive polymer layer can be improved. Generation and progress of radical reaction in 32 can be effectively suppressed.

  In addition, when using the above mixed liquid, when using a sulfonic acid metal salt that functions as a dopant and oxidizing agent, the concentration of metal ions as an oxidizing agent in the mixed liquid becomes excessive due to the configuration of the sulfonic acid metal salt. There is a tendency. However, according to the manufacturing method of the solid electrolytic capacitor of the present embodiment, since the conductive polymer layer 32 containing the C12A7 compound can be formed in addition to the dopant and the oxidizing agent, the metal ions are present excessively. Can be compensated by the C12A7 compound.

  As mentioned above, although demonstrated using the manufacturing method of the winding type solid electrolytic capacitor shown in FIG. 1, the manufacturing method of the solid electrolytic capacitor of this invention is not restricted to this, For example, on the anode body which consists of a sintered compact, A solid electrolytic capacitor having a conductive polymer layer and a method for producing a solid electrolytic capacitor having a conductive polymer layer on an anode body made of a metal plate are also included.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Examples 1-6>
In Example 1, a wound type solid electrolytic capacitor was produced. Below, the specific manufacturing method of a solid electrolytic capacitor is demonstrated.

(Process for preparing anode body)
First, after etching the aluminum foil to roughen the surface of the aluminum foil, a dielectric coating was formed on the surface of the aluminum foil by chemical conversion treatment. The chemical conversion treatment was performed by immersing an aluminum foil in an ammonium adipate solution and applying a voltage thereto. And this aluminum foil was cut | judged so that length x width might be set to 6 mm x 120 mm, and the anode body was prepared.

(Production of wound body)
Next, a separator and a cathode body having the same area as the anode body were prepared, and the anode body and the cathode body were wound through the separator while a lead tab was wound. Next, the end of the outer surface of the wound body was stuck with a winding tape to produce a wound body. Aluminum foil was used as the cathode body, and a lead wire was connected to the end portion protruding from the wound body of the lead tab. Then, the produced wound body was subjected to a chemical conversion treatment again to form a dielectric film on the cut end portion of the anode body.

(Process of forming a conductive polymer layer)
1. Preparation of C12A7 Compound A raw material containing Ca and Al at an atomic equivalent ratio of 12:14 was prepared, and this was subjected to a solid phase reaction at 1350 ° C. to produce a sintered body made of C12A7. Next, in the band melting method (FZ method), the molten zone in the sintered body is moved by pulling up the sintered body while condensing infrared rays on the produced sintered body, and the molten zone-solidified portion C12A7 single crystals were continuously grown from the interface.

  The single crystal of C12A7 produced by the FZ method is processed into a thin plate of 5 mm × 5 mm × 10 mm, put into this single crystal thin plate, a calcium metal piece, and a quartz tube and vacuum-sealed, and held at 700 ° C. for 240 hours. did. Then, a sample in the quartz tube was taken out, pulverized with a ball mill for 1 week, and the powder that passed through the 20 μm mesh was made into a C12A7 compound.

2. Preparation of Mixed Liquid A mixed liquid containing 3,4-ethylenedioxythiophene as a precursor monomer, p-toluenesulfonic acid ferric acid as a dopant, and the C12A7 compound was prepared. Specifically, a C12A7 compound was added to a butanol solution containing 3,4-ethylenedioxythiophene and ferric p-toluenesulfonate and stirred to prepare a mixed solution. Table 1 shows the content (mol) of each additive in the mixed solution in Examples 1 to 6.

  Each of the produced wound bodies was immersed in each mixed solution for about 3 to 10 seconds, and then the wound body was pulled up and allowed to stand at room temperature for 3 hours to form a conductive polymer layer. And the winding body in which the conductive polymer layer was formed, ie, the capacitor | condenser element, was heated at 180 degreeC, and the solvent which remains in a winding body was removed.

(Process of sealing the capacitor element)
Next, the capacitor element was sealed to produce a solid electrolytic capacitor.

  Specifically, first, a rubber packing, which is a sealing member that is formed so that a lead wire passes through the capacitor element in a bottomed case so that the lead wire is positioned on the upper surface of the bottomed case opening. Was placed above the capacitor element, and the capacitor element was sealed in the bottomed case. Then, the vicinity of the open end of the bottomed case was curled after lateral drawing, and a seat plate was placed on the processed curled portion, thereby manufacturing a wound type solid electrolytic capacitor.

<Comparative Examples 1-4>
50 solid electrolytic capacitors were produced in the same manner as in Example 1 except that phenolsulfonic acid was used instead of the C12A7 compound and the addition concentration was changed. Table 2 shows the concentration of each additive in the mixed solution in Comparative Examples 1 to 4.

<Characteristic evaluation>
The rated voltage of the solid electrolytic capacitor of each example and each comparative example was 4 WV, and the rated capacity was 150 μF. Further, the outer shape of the solid electrolytic capacitor was 6.3 mm in diameter and 6 mm in height.

(Initial capacitance)
Thirty pieces were randomly selected from 50 solid electrolytic capacitors of each example and each comparative example. The initial capacitance (μF) at a frequency of 120 Hz of each solid electrolytic capacitor was measured for 30 solid electrolytic capacitors in each of the selected Examples and Comparative Examples using an LCR meter for 4-terminal measurement. The average values of the measured results are shown in Table 3.

(Initial ESR)
With respect to 30 solid electrolytic capacitors in each of the selected examples and comparative examples, ESR (mΩ) at a frequency of 100 kHz of each solid electrolytic capacitor was measured using an LCR meter for four-terminal measurement. Table 3 shows the average values of the measured results.

(Reflow test)
A reflow test was performed on the solid electrolytic capacitors of each Example and each Comparative Example. Specifically, the solid electrolytic capacitors of the examples and comparative examples were allowed to stand for 12 hours in an environment of 121 ° C. or higher and 2 atmospheres, and then forced to absorb moisture, and then maintained at 230 ° C. or higher and a maximum temperature of 250 ° C. for 30 seconds. .

(Capacitance change rate)
About 30 solid electrolytic capacitors of each Example and each comparative example after a reflow test, the electrostatic capacitance was measured by the method similar to the above, and the average value of each solid electrolytic capacitor was computed. Then, by substituting C ₀ for the initial capacitance and C for the capacitance after the reflow test, the capacitance change rate ΔC (%) was calculated. The results are shown in Table 2.
ΔC (%) = (C−C ₀ ) / C ₀ × 100 (1)
(ESR change rate)
For each of the 30 solid electrolytic capacitors in each Example and each Comparative Example after the reflow test, ESR was measured by the same method as described above, and the average value of each solid electrolytic capacitor was calculated. Then, by substituting the initial ESR as R ₀ and the ESR after the reflow test as R into the following formula (2), the ESR change rate ΔR (times) was calculated. The results are shown in Table 2.
ΔR (times) = R / R ₀ (2)

  When comparing Examples 1 to 6 with Comparative Example 1 with reference to Tables 1 to 3, 0.01 to 0.1 mol of C12A7 compound is contained in addition to the precursor monomer, oxidizing agent and dopant necessary for the polymerization reaction system. When the conductive polymer layer is formed using the mixed liquid (Examples 1 to 6), the capacitance change rate and ESR are higher than when the mixed liquid not containing the C12A7 compound is not used (Comparative Example 1). The rate of change was low. This is presumably because the radical decomposition of the conductive polymer layer was suppressed by the presence of the C12A7 compound in the conductive polymer layer, and the deterioration of the electrical characteristics of the solid electrolytic capacitor was suppressed.

  Moreover, when Examples 1-6 were compared with Comparative Examples 2-4, when phenolsulfonic acid was used instead of C12A7 compound, it turned out that initial stage ESR increases and also ESR change rate becomes large. . This is considered to be because, when phenolsulfonic acid is used, the conductive polymer layer deteriorates due to re-doping by reflow, and as a result, the resistance of the conductive polymer layer is increased. On the other hand, when the C12A7 compound was used, an increase in the initial ESR could be suppressed, and the ESR change rate could be suppressed.

  Moreover, when Examples 1-6 were compared, it turned out that an ESR change rate is further suppressed when content of the C12A7 compound in a liquid mixture is 0.03 mol or more. In particular, in the case of 0.03 mol or more and 0.09 mol or less, both the capacitance and ESR characteristics could be kept good.

  From the above results, when the chemical polymerization method is used, the content of the C12A7 compound with respect to the dopant is 0.01 mol% or more and 0.1 mol% or less in the mixed solution, in other words, the dopant content of the C12A7 compound in the polymerization reaction system. It was found that both the electrostatic capacity and ESR characteristics of the solid electrolytic capacitor can be maintained well when the amount is 1/100 times the mole and 1/10 times the mole. Furthermore, in the mixed solution, when the content of the C12A7 compound with respect to the dopant is 0.03 mol% or more or 0.09 mol% or less, in other words, when it is 1/300 times mol or more, or 9/100 times mol or less. It was found that both characteristics can be kept good.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be used for a solid electrolytic capacitor, and in particular, can be suitably used for a solid electrolytic capacitor including a conductive polymer layer.

  10 Capacitor element, 11 Bottomed case, 12 Sealing member, 13 Seat plate, 14A, 14B Lead wire, 15A, 15B Lead tab, 21, 51 Anode body, 22 Cathode body, 23 Separator, 24 Winding tape, 31 Dielectric Coating, 32 conductive polymer layer.

Claims (7)

An anode body having a dielectric coating on the surface;
A conductive polymer layer provided on the anode body,
Wherein the conductive polymer layer includes the dopant and 12CaO · 7Al ₂ O ₃ compound, a solid electrolytic capacitor.   The solid electrolytic capacitor according to claim 1, wherein the conductive polymer layer is formed by a chemical polymerization method.   The solid electrolytic capacitor according to claim 2, wherein the conductive polymer layer includes an oxidizing agent used in the chemical polymerization method. For the conductive polymer layer, a mixed liquid containing a conductive polymer precursor monomer constituting the conductive polymer layer, the dopant, the oxidizing agent, and the 12CaO · 7Al ₂ O ₃ compound was used. wherein is formed by chemical polymerization, in the mixed solution, the content of the 12CaO · 7Al ₂ O ₃ compound to the dopant is less than 0.01 mol% or more 0.1 mol%, in claim 2 or 3 The solid electrolytic capacitor as described. A method for producing a solid electrolytic capacitor having a conductive polymer layer,
Including a step of forming a conductive polymer layer on the anode body provided with a dielectric coating on the surface;
In the step of forming the conductive polymer layer,
The precursor monomer of the conductive polymer constituting the conductive polymer layer, in the presence of a dopant and 12CaO · 7Al ₂ O ₃ compound is polymerized by a chemical polymerization method, the said dopant 12CaO · 7Al ₂ O ₃ A method for producing a solid electrolytic capacitor, wherein the conductive polymer layer containing a compound is formed. In the step of forming the conductive polymer layer, the conductive polymer layer is formed using a mixed solution containing an oxidant, the precursor monomer, the dopant, and the 12CaO · 7Al ₂ O ₃ compound. The manufacturing method of the solid electrolytic capacitor of Claim 5. In the mixed solution, the content of the 12CaO · 7Al ₂ O ₃ compound to the dopant is less than 0.01 mol% or more 0.1 mol%, the manufacturing method of solid electrolytic capacitor according to claim 6.

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