JP2012033644A - Solid electrolytic capacitor manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor manufacturing method capable of reducing an equivalent series resistance (ESR).SOLUTION: A solid electrolytic capacitor manufacturing method comprises: a step of forming an anode 1; a step of forming a dielectric layer 2 and a first coupling agent layer 3 on the surface of the anode 1 by electrolytically forming the anode 1 in a solution including the coupling agent that coupled two phosphonic acid groups via a hydrocarbon group; a step of forming a first conductive polymer layer 4 on the first coupling agent layer 3; and a step of forming a cathode layer 11 above the first conductive polymer layer 4.

Description

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

  In recent years, along with the downsizing and weight reduction of electronic devices, there has been a demand for high-frequency capacitors with a small size and large capacity. As such capacitors, sintering of valve metals such as tantalum, niobium, titanium or aluminum is required. A solid electrolytic capacitor has been proposed in which a surface of an anode formed of a body is oxidized to form a dielectric layer, and a solid electrolyte layer is provided on the dielectric layer. As the solid electrolyte layer, an equivalent series resistance (ESR) is reduced by using a conductive polymer.

  However, if the adhesion between the dielectric layer formed from an inorganic material and the conductive polymer layer formed from an organic material is lowered, there is a problem that ESR increases.

  In Patent Documents 1 to 3, it is proposed to form a conductive polymer layer by forming a dielectric layer on the surface of the anode and then treating the surface of the dielectric layer with a silane coupling agent.

  In Patent Document 4, it is proposed to repeatedly perform treatment with a silane coupling agent and formation of a conductive polymer layer on the surface of a dielectric layer.

  In Patent Document 5, a first conductive polymer layer is partially formed on a dielectric layer, and then a silane is formed on the dielectric layer on which the first conductive polymer layer is not formed. It has been proposed to form a coupling agent-treated layer and then form a second conductive polymer layer on the first conductive polymer layer and the silane coupling agent-treated layer.

  In Patent Document 6, an anode is immersed in a solution to which a silane coupling agent is added, and the anode is subjected to an electrolytic conversion treatment, thereby forming a dielectric layer on the surface of the anode and forming a silane coupling agent layer. It has been proposed. This describes that the adhesion between the dielectric layer and the conductive polymer layer is improved, and ESR can be reduced.

  Patent Document 7 proposes a method for manufacturing an electrolytic capacitor in which an anode is immersed in a solution containing at least one of a surfactant and a dopant, and the anode is subjected to electrolytic conversion treatment. Thus, it is described that the capacity characteristic can be stably improved.

  However, since the reaction of the silane coupling agent is initiated by a hydrolysis reaction with water, there is a problem that it is easily affected by moisture in the atmosphere. Further, the amount of adsorption and the amount of reaction of the silane coupling agent vary depending on the state of the surface of the substrate. For this reason, in the said prior art using a silane coupling agent, there exists a problem that sufficient effect is not acquired in reduction of ESR etc. Further, in the above conventional technique using a dopant or a surfactant, since the bond between the dopant or the surfactant and the dielectric layer is weak, a sufficient effect is not obtained in reducing the ESR.

Japanese Patent Laid-Open No. 2-74021 JP-A-4-73924 JP-A-8-293436 JP 11-329900 A JP 2006-140443 A JP 2007-266202 A JP 2005-175015 A

  The objective of this invention is providing the manufacturing method of the solid electrolytic capacitor which can reduce ESR.

  The method for producing a solid electrolytic capacitor of the present invention is characterized by including a step of subjecting the anode to electrolytic conversion treatment in a solution containing a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group.

  The method for producing a solid electrolytic capacitor according to the first aspect of the present invention includes a step of forming an anode, and an electrolytic formation of the anode in a solution containing a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group. A step of forming a dielectric layer and a first coupling agent layer on the surface of the anode; a step of forming a first conductive polymer layer on the first coupling agent layer; And a step of forming a cathode layer on one conductive polymer layer.

  The method for manufacturing a solid electrolytic capacitor according to the second aspect of the present invention includes a step of forming an anode, a step of forming a dielectric layer on the surface of the anode, and a first conductive polymer layer on the dielectric layer. The anode formed with the first conductive polymer layer is subjected to an electrolytic conversion treatment in a solution containing a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group. Forming a coupling agent layer on the conductive polymer layer, forming a second conductive polymer layer on the coupling agent layer, and on the second conductive polymer layer And a step of forming a cathode layer.

  The solid electrolytic capacitor manufacturing method according to the third aspect of the present invention is the solid electrolytic capacitor manufacturing method according to the first aspect of the present invention, wherein the anode formed with the first conductive polymer layer is used as a coupling agent. Forming a second coupling agent layer on the first conductive polymer layer by performing an electrolytic conversion treatment in a solution containing the second conductive agent on the second coupling agent layer And a step of forming a cathode layer. The step of forming a cathode layer is a step of forming a cathode layer on the second conductive polymer layer.

  The coupling agent used in the present invention is a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group. Examples of such a coupling agent include those represented by the following general formula (1).

(Wherein R represents — (CH ₂ ) _n —, — (CH ₂ O) _n —, — (C ₂ H ₅ O) _n —, or —O— (CH ₂ ) _n —O—, n represents an integer of 1 to 18.)

  According to the manufacturing method of the present invention, ESR can be reduced.

1 is a schematic cross-sectional view showing a solid electrolytic capacitor of an embodiment according to the first aspect of the present invention. FIG. 2 is an enlarged schematic cross-sectional view showing an anode, a dielectric layer, a first coupling agent layer, a first conductive polymer layer, and a cathode layer of the solid electrolytic capacitor shown in FIG. 1. Typical sectional drawing which shows the solid electrolytic capacitor of embodiment according to the 2nd aspect of this invention. Typical sectional drawing which shows the solid electrolytic capacitor of embodiment according to the 3rd aspect of this invention.

  Hereinafter, the present invention will be described in more detail.

<First aspect of the present invention>
In the first aspect of the present invention, after the anode is formed, the anode is subjected to an electrolytic conversion treatment in a solution containing a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group. A dielectric layer and a first coupling agent layer are formed. A first conductive polymer layer is formed on the first coupling agent layer.

  Since the anode is subjected to electrolytic conversion treatment in a solution containing a coupling agent, a dielectric layer is formed on the surface of the anode, and the coupling agent is adsorbed on the surface of the formed dielectric layer to increase hydrophobicity. be able to. By forming the hydrophobic first coupling agent layer on the surface of the dielectric layer, the adhesion between the dielectric layer and the first conductive polymer layer can be enhanced. Furthermore, since the first coupling agent layer can be present in the defective portion of the dielectric layer, the insulation between the anode and the first conductive polymer layer can be enhanced. For this reason, ESR of the solid electrolytic capacitor can be reduced, and leakage current can also be reduced.

  In the first aspect of the present invention, since the surface treatment is performed while applying a voltage to the anode, the coupling agent can be present uniformly and in a large amount on the surface of the dielectric layer. For this reason, the hydrophobicity by the coupling agent layer on the surface of the dielectric layer can be enhanced.

  In the present invention, a coupling agent having two phosphonic acid groups is used. Since the phosphonic acid group directly reacts with the oxide film of the dielectric layer, the amount of reaction to the dielectric layer can be increased as compared with the case where a silane coupling agent is used. By increasing the reaction amount, the coverage of the coupling agent layer on the dielectric layer can be increased. In addition, many other phosphonic acid groups of the coupling agent can be present on the surface of the coupling agent layer. For this reason, when the first conductive polymer layer is formed on the coupling agent, the coverage of the first conductive polymer layer on the dielectric layer can be increased.

  As described above, the reaction of the silane coupling agent is hydrolyzed with water to become silanol (Si-OH), partially condensed into an oligomer state, and subsequently adsorbed to hydroxyl groups on the inorganic surface. Heat treatment of the inorganic material causes a dehydration condensation reaction to form a strong chemical bond. In this reaction, since the hydrolysis reaction starts with water, it is necessary to work in an atmosphere that does not contain moisture in the atmosphere or solvent, or to use it immediately after preparing a silane coupling agent solution.

  On the other hand, the coupling agent used in the present invention has a phosphonic acid group, and since it has a structure (P-OH) having a hydroxyl group from the beginning, a hydrolysis reaction like a silane coupling agent is performed. do not need. For this reason, it is not affected by moisture in the atmosphere or in the solvent. Therefore, the coupling agent having a phosphonic acid group is excellent in storage stability, and according to the present invention, a solid electrolytic capacitor with stable quality can be produced.

  In the first aspect of the present invention, a cathode layer is formed on the first conductive polymer layer. Therefore, the cathode layer may be directly formed on the first conductive polymer layer, or the cathode layer may be directly formed on the first conductive polymer layer through another layer. . For example, a second conductive polymer layer may be formed on the first conductive polymer layer, and a cathode layer may be formed on the second conductive polymer layer.

<Second aspect of the present invention>
In the second aspect of the present invention, a step of forming an anode, a step of forming a dielectric layer on the surface of the anode, a step of forming a first conductive polymer layer on the dielectric layer, The anode formed with the first conductive polymer layer is subjected to electrolytic conversion treatment in a solution containing a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group, and the first conductive polymer layer is formed. Forming a coupling agent layer on the substrate, forming a second conductive polymer layer on the coupling agent layer, and forming a cathode layer on the second conductive polymer layer A process.

  In the second aspect of the present invention, the anode on which the first conductive polymer layer is formed is subjected to electrolytic conversion treatment in a solution containing a coupling agent, and a cup is formed on the first conductive polymer layer. A ring agent layer is formed. When the coupling agent layer is formed, the conductivity of the first conductive polymer layer is improved because the phosphonic acid group of the coupling agent having a diphosphonic acid group is doped into the first conductive polymer layer. ESR can be reduced.

  Furthermore, in the second aspect of the present invention, a first conductive polymer layer, a coupling agent layer, and a second conductive polymer layer are sequentially formed. Since the other phosphonic acid group of the coupling agent doped in the first conductive polymer layer functions as a dopant for the conductive polymer, the coupling agent layer and the second conductive polymer layer are combined. The adhesion between the first conductive polymer layer and the second conductive polymer layer can be further enhanced through the coupling agent layer. Therefore, ESR can be further reduced.

  In addition, when a defect is generated in the dielectric layer by a polymerization reaction or process when forming the first conductive polymer layer, a coupling agent layer can be formed on the defective portion. For this reason, the leakage current can be reduced.

  In the second aspect of the present invention, a third conductive polymer layer is formed on the second conductive polymer layer, and a cathode layer is formed on the third conductive polymer layer. Also good. In this case, a coupling agent layer may be further formed between the second conductive polymer layer and the third conductive polymer layer. In this case, the adhesion between the second conductive polymer layer and the third conductive polymer layer can be improved via the coupling agent layer. For this reason, ESR can be further reduced.

<Third Aspect of the Present Invention>
According to a third aspect of the present invention, in the manufacturing method according to the first aspect of the present invention, the anode on which the first conductive polymer layer is formed is subjected to an electrolytic conversion treatment in a solution containing a coupling agent, A step of forming a second coupling agent layer on the first conductive polymer layer; and a step of forming a second conductive polymer layer on the second coupling agent layer. Yes.

  Therefore, the third aspect of the present invention exhibits both the operational effects in the first aspect of the present invention and the operational effects in the second aspect.

  Therefore, the coverage of the dielectric layer by the first coupling agent layer is increased, the adhesion between the dielectric layer and the first conductive polymer layer can be increased, and ESR can be reduced. Furthermore, when the second coupling agent layer is formed, the first conductive polymer layer is doped with the phosphonic acid group of the coupling agent, so that the conductivity of the first conductive polymer layer is increased. And ESR can be further reduced.

  In addition, a first conductive polymer layer, a second coupling agent layer, and a second conductive polymer layer are sequentially formed. For this reason, the other phosphonic acid group of the coupling agent doped in the first conductive polymer layer functions as a dopant of the conductive polymer, and the second coupling agent layer and the second conductive polymer The layers are bonded to each other, so that the adhesion between the first conductive polymer layer and the second conductive polymer layer can be further enhanced through the second coupling agent layer. For this reason, ESR can be further reduced.

  In addition, when a defect is generated in the dielectric layer by a polymerization reaction or process when forming the first conductive polymer layer, a coupling agent layer can be formed on the defective portion.

  In the third aspect of the present invention, a third conductive polymer layer is formed on the second conductive polymer layer, and a cathode layer is formed on the third conductive polymer layer. Also good. In this case, a third coupling agent layer may be formed between the second conductive polymer layer and the third conductive polymer layer. In this case, the adhesion between the second conductive polymer layer and the third conductive polymer layer can be improved via the third coupling agent layer. For this reason, ESR can be further reduced.

<Coupling agent>
The coupling agent used in the present invention is a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group. Examples of the hydrocarbon group include R shown in the general formula (1). That is, an alkylene group, a polymethyleneoxy group, a polyethyleneoxy group, a diether alkyl group, etc. are mentioned. Among these, R is particularly preferably an alkylene group having 1 to 18 carbon atoms. As such a thing, what is represented by General formula (2) shown below is mentioned.

  (In the formula, n represents an integer of 1 to 18.)

  Specific examples of the coupling agent represented by the general formula (2) include methylenediphosphonic acid, 1,8-octanediphosphonic acid, 12-phosphonododecylphosphonic acid ((12 -Phosphonododecyl) phosphonic acid).

<Solution used for electrolytic conversion treatment>
In the present invention, the solution used for the electrolytic conversion treatment is preferably an aqueous solution or an acid aqueous solution, and the acid aqueous solution is particularly preferably a phosphoric acid aqueous solution. Further, the solution may contain a polar solvent. As a polar solvent, it is preferable that it is excellent in compatibility with aqueous solution or acid aqueous solution, From this viewpoint, polar protic solvents, such as alcohol, are used preferably. In particular, it is preferable to use alcohols such as methanol, ethanol and isopropyl alcohol.

<Conductive polymer of conductive polymer layer>
Examples of the conductive polymer monomer that forms the conductive polymer in the present invention include pyrrole, thiophene, aniline, and derivatives thereof. The conductive polymer layer in the present invention can be formed by chemical oxidative polymerization or electrochemical electrolytic polymerization.

<Embodiment shown in FIG. 1>
FIG. 1 is a schematic cross-sectional view showing a solid electrolytic capacitor of an embodiment according to the first aspect of the present invention.

  A part of the anode lead 12 is embedded in the anode 1 having a substantially rectangular parallelepiped shape. A dielectric layer 2 is formed on the surface of the anode 1. The anode 1 is formed from a porous body obtained by sintering a powder made of a valve metal or an alloy thereof. Examples of the valve action metal include tantalum, niobium, titanium, aluminum, haufnium, and zirconium. As an alloy of valve action metal, the alloy which contains these valve action metals 50 atomic% or more is mentioned. Specifically, the porous anode 1 is formed by sintering a large number of powders at intervals, and a dielectric layer is formed on the surface of the powder constituting the anode 1. 2 is formed.

  A first coupling agent layer 3 is formed on the dielectric layer 2. The dielectric layer 2 and the first coupling agent layer 3 are formed by immersing the anode in a solution containing a coupling agent having two phosphonic acid groups and subjecting the anode to electrolytic conversion treatment.

  A first conductive polymer layer 4 is formed on the first coupling agent layer 3. The first conductive polymer layer 4 is also formed on the first coupling agent layer 3 inside the anode 1. In the present embodiment, the first conductive polymer layer 4 is formed by chemical oxidative polymerization.

  A second conductive polymer layer 5 is formed on the first conductive polymer layer 4. The second conductive polymer layer 5 is formed so as to fill the gap between the powders constituting the anode 1. In the present embodiment, the second conductive polymer layer 5 is formed by electrochemical electrolytic polymerization.

  A carbon layer 9 is formed on the second conductive polymer layer 5 on the outer periphery of the anode 1. The carbon layer 9 is formed by applying a carbon paste and drying it. A silver layer 10 is formed on the carbon layer 9. The silver layer 10 is formed by applying a silver paste and drying. A cathode layer 11 is composed of the carbon layer 9 and the silver layer 10.

  FIG. 2 is a schematic cross-sectional view showing the inside of the anode 1 in the present embodiment in an enlarged manner. As shown in FIG. 2, the anode 1 is a porous body, and a dielectric layer 2 is formed also on the surface inside the porous body. On the dielectric layer 2, the first cup is formed. A ring agent layer 3 is formed, and a first conductive polymer layer 4 is formed on the first coupling agent layer 3. The first coupling agent layer 3 and the first conductive polymer layer 4 are also formed inside the porous body that is the anode 1. The second conductive polymer layer 5 is formed on the first conductive polymer layer 4. The second conductive polymer layer 5 may be formed inside the porous body that is the anode 1.

  As described above, the carbon layer 9 and the silver layer 10 are formed on the second conductive polymer layer 5 on the outer peripheral portion of the anode 1.

  A capacitor element is formed as described above. A positive electrode terminal and a negative electrode terminal are connected to the capacitor element, and the resin outer package is molded so that ends of the positive electrode terminal and the negative electrode terminal are exposed, thereby producing a solid electrolytic capacitor. The cathode terminal is connected to the silver layer 10 via a conductive adhesive layer, and the anode terminal is connected to the anode lead 12 by welding or the like.

  In the present embodiment, the anode 1 is dipped in a solution containing a coupling agent having two phosphonic acid groups, and the anode 1 is subjected to electrolytic conversion treatment, whereby the dielectric layer 2 and the first layer 1 are formed on the surface of the anode 1. The coupling agent layer 3 is formed. For this reason, the coverage of the dielectric layer 2 by the first coupling agent layer 3 can be increased, and the adhesion between the dielectric layer 2 and the first conductive polymer layer 4 can be increased. For this reason, ESR of a solid electrolytic capacitor can be reduced.

<Embodiment shown in FIG. 3>
FIG. 3 is a schematic cross-sectional view showing a solid electrolytic capacitor manufactured according to the second aspect of the present invention.

  As shown in FIG. 3, a dielectric layer 2 is formed on the anode 1. The dielectric layer 2 is formed by immersing the anode 1 in a solution such as an aqueous phosphoric acid solution that does not contain a coupling agent, and subjecting the anode 1 to electrolytic conversion treatment.

  A first conductive polymer layer 4 is formed on the dielectric layer 2. The first conductive polymer layer 4 is formed by chemical oxidative polymerization. The dielectric layer 2 and the first conductive polymer layer 4 are formed on the dielectric layer 2 inside the anode 1.

  A coupling agent layer 8 is formed on the first conductive polymer layer. The coupling agent layer 8 is obtained by immersing the anode 1 on which the first conductive polymer layer 4 is formed in a solution containing a coupling agent having two phosphonic acid groups, and subjecting the anode 1 to an electrolytic conversion treatment. Is formed. Therefore, the coupling agent layer 8 is formed on the first conductive polymer layer 4 inside the anode 1. The second conductive polymer layer 5 is formed so as to fill the gap between the powders constituting the anode 1. In the present embodiment, the second conductive polymer layer 5 is formed by electrochemical electrolytic polymerization.

  A cathode layer 11 composed of a carbon layer 9 and a silver layer 10 is formed on the second conductive polymer layer 5.

  The capacitor element is formed as described above, the anode terminal and the cathode terminal are connected in the same manner as in the embodiment shown in FIG. 1, and the resin outer package is formed to produce a solid electrolytic capacitor.

  In the present embodiment, when the coupling agent layer 8 is formed, the phosphonic acid group of the coupling agent is doped into the first conductive polymer layer 4, so that the first conductive polymer layer 4 Conductivity can be improved and ESR can be reduced.

  Further, since the coupling agent layer 8 is formed between the first conductive polymer layer 4 and the second conductive polymer layer 5, the first conductive polymer layer 4 and the second conductive polymer layer 5 are formed. The adhesion between the conductive polymer layers 5 can be further increased, and the ESR can be further reduced.

<Embodiment shown in FIG. 4>
FIG. 4 is a schematic cross-sectional view showing a solid electrolytic capacitor manufactured by the method according to the third aspect of the present invention.

  As shown in FIG. 4, the dielectric layer 2 and the first coupling agent layer 3 are formed on the anode 1 in the same manner as the embodiment shown in FIG. Similarly to the embodiment shown in FIG. 3, a second coupling agent layer 8 is formed between the first conductive polymer layer 4 and the second conductive polymer layer 5.

  Therefore, according to the present embodiment, the adhesion between the dielectric layer 2 and the first conductive polymer layer 4 is enhanced by the presence of the first coupling agent layer 3 interposed therebetween. ESR can be reduced.

  Further, the first conductive polymer layer 4 can be doped with the phosphonic acid group of the coupling agent layer 8 in the second coupling agent layer 8, and the conductivity of the first conductive polymer layer 4 can be doped. And ESR can be further reduced.

  Further, by interposing the second coupling agent layer 8 between the first conductive polymer layer 4 and the second conductive polymer layer 5, the first conductive polymer layer 4 and the second conductive polymer layer 4 The adhesion between the two conductive polymer layers 5 can be further increased, and the ESR can be further reduced.

  Hereinafter, the present invention will be described in more detail by way of specific examples according to the present invention, but the present invention is not limited to the following examples.

Example 1
This example is an example according to the second aspect of the present invention.

  Therefore, as shown in FIG. 3, the first conductive polymer layer 4 is formed on the dielectric layer 2, and the gap between the first conductive polymer layer 4 and the second conductive polymer layer 5 is formed. The coupling agent layer 8 is formed on the substrate. Specifically, the solid electrolytic capacitor of this example was manufactured as follows.

  A dielectric layer 2 is formed on the surface of the anode 1 by applying 10 V to the anode 1 using a constant voltage in a 0.1 wt% phosphoric acid aqueous solution at 65 ° C. Formed.

  Next, the anode 1 on which the dielectric layer 2 is formed is immersed in an ethanol solution containing 3.0M (mol / liter) of pyrrole for 5 minutes, and then 0.1M ammonium persulfate and 0.1M alkylnaphthalenesulfonic acid are contained. The first conductive polymer layer 4 was formed on the dielectric layer 2 by immersing in an aqueous solution at 25 ° C. for 5 minutes.

  Next, 1,8-octanediphosphonic acid (manufactured by Aldrich), which is a coupling agent having two phosphonic acid groups, is dissolved in pure water so as to have a concentration of 0.5 mM (mmol / liter). Thus, an electrolytic solution was prepared. By immersing the anode 1 on which the first conductive polymer layer 4 is formed in this electrolytic solution, applying a constant voltage of 10 V to the anode 1 at 65 ° C., and performing an electrolytic conversion treatment for 1 hour, A coupling agent layer 8 was formed on the conductive polymer layer 4.

  Next, the anode 1 on which the coupling agent layer 8 is formed is immersed in an aqueous solution at 25 ° C. containing 0.2M pyrrole and 0.2M alkylnaphthalenesulfonic acid, and the first conductive polymer layer 4 is used as the anode. The second conductive polymer layer 5 was formed by applying a current of 0.5 mA for 3 hours.

  Thereafter, as described above, an anode terminal and a cathode terminal were connected, and a resin molded body was formed by transfer molding with an epoxy resin, thereby producing a solid electrolytic capacitor.

(Example 2)
In Example 1, as an electrolytic solution for forming the coupling agent layer 8, 1,8-octanediphosphonic acid (manufactured by Aldrich) was added to 0.5 mM (mmol / mmol) in a 0.1 wt% phosphoric acid aqueous solution. A solid electrolytic capacitor was produced in the same manner as in Example 1 except that an electrolytic solution containing a concentration of 1 liter) was used.

(Example 3)
This example is an example according to the first aspect of the present invention. Therefore, the anode 1 is immersed in a solution containing a coupling agent and subjected to an electrolytic conversion treatment, whereby the dielectric layer 2 and the first coupling agent layer 3 are formed on the anode 1 as shown in FIG. Is forming. Specifically, the dielectric layer 2 and the first coupling agent layer 3 were formed on the anode 1 as follows.

  The anode 1 was immersed in an electrolytic solution containing 1,8-octanediphosphonic acid (manufactured by Aldrich), which is a coupling agent having two phosphonic acid groups, in pure water at a concentration of 0.5 mM. A dielectric layer 2 and a first coupling agent layer 3 were formed on the surface of the anode 1 by applying a constant voltage of 10 V to the anode 1 in an electrolytic solution at 65 ° C. and subjecting it to an electrolytic conversion treatment for 10 hours.

  Next, the anode 1 is immersed in an ethanol solution containing 3.0 M of pyrrole for 5 minutes, and then immersed in an aqueous solution containing 0.1 M ammonium persulfate and 0.1 M alkylnaphthalenesulfonic acid at 25 ° C. for 5 minutes. A first conductive polymer layer 4 was formed on the first coupling agent layer 3.

  Next, the anode 1 on which the first conductive polymer layer 4 was formed was immersed in an aqueous solution at 25 ° C. containing pyrrole 0.2M and alkylnaphthalenesulfonic acid 0.2M, and the first conductive polymer layer The second conductive polymer layer 5 was formed by applying a current of 0.5 mA for 3 hours using 4 as an anode.

  After forming the second conductive polymer layer 5, the cathode layer 11 is formed in the same manner as in Example 1, the anode terminal and the cathode terminal are connected, the resin sheathing is formed, and the solid electrolytic capacitor is formed. Produced.

Example 4
In Example 3, 1,8-octanediphosphonic acid (manufactured by Aldrich) was used as an electrolytic solution for forming the dielectric layer 2 and the first coupling agent layer 3 in a 0.1 wt% phosphoric acid aqueous solution. ) Was used in the same manner as in Example 3 except that an electrolytic solution containing 0.5 mM was used.

(Example 5)
This example is an example according to the third aspect of the present invention.

  Therefore, as shown in FIG. 4, the anode 1 is subjected to electrolytic conversion treatment in a solution containing a coupling agent to form a dielectric layer 2 and a first coupling agent layer 3 on the anode 1, and A second coupling agent layer 8 is formed between the first conductive polymer layer 4 and the second conductive polymer layer 5.

  Specifically, the dielectric layer 2 and the first coupling agent layer 3 are formed on the anode 1 in the same manner as in Example 4, and the first conductive polymer is formed in the same manner as in Example 1. A second coupling agent layer 8 was formed on the layer 4, and a second conductive polymer layer 5 was formed thereon.

  After forming the second conductive polymer layer 5, the cathode layer 11 is formed in the same manner as in Example 1, the anode terminal and the cathode terminal are connected, the resin sheathing is formed, and the solid electrolytic capacitor is formed. Produced.

(Example 6)
As an electrolytic solution for electrolytic conversion treatment, an electrolytic solution containing 1,8-octanediphosphonic acid at a concentration of 0.5 mM in a 0.1% by weight phosphoric acid aqueous solution is used. A solid electrolytic capacitor was produced in the same manner as in Example 5 except that the coupling agent layer 3 and the second coupling agent layer 8 were formed.

(Comparative Example 1)
In Example 5, a silane coupling agent was used in place of the coupling agent having a phosphonic acid group of the present invention. As the silane coupling agent, 3-mercaptopropyltrimethoxysilane (trade name “KBM-803”, a silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd.) was used. By immersing the anode 1 in a 25 ° C aqueous solution containing 0.1M 3-mercaptopropyltrimethoxysilane for 10 minutes, drying at 130 ° C for 30 minutes, washing with pure water, and drying again at 100 ° C The 1st coupling agent layer 3 and the 2nd coupling agent layer 8 were formed. Other than that was carried out similarly to Example 5, and produced the solid electrolytic capacitor. Therefore, in this comparative example, the coupling agent layer is not formed by electrolytic conversion treatment in the solution containing the coupling agent, but by drying after the solution containing the silane coupling agent is brought into contact with the surface and then dried. Formed.

[Evaluation of characteristics of solid electrolytic capacitors]
ESR was measured for each obtained solid electrolytic capacitor. ESR was measured at a frequency of 100 kHz using an LCR meter (inductance-capacitance-resistance measuring device). The measurement results are shown in Table 1. In addition, the value shown in Table 1 is the layer position on the basis of Comparative Example 1.

  As described above, Example 1 and Example 2 are examples according to the second aspect of the present invention, Example 3 and Example 4 are examples according to the first aspect of the present invention, and Example 5 And Example 6 is an example according to the third aspect of the present invention. Moreover, in Example 1, Example 3, and Example 5, the aqueous solution which melt | dissolved the coupling agent in the pure water is used as an electrolyte solution for electrolytic conversion treatment. In Example 2, Example 4, and Example 6, the solution which melt | dissolved the coupling agent in 0.1 weight% phosphoric acid aqueous solution is used as an electrolyte solution for electrolytic conversion treatment.

  As shown in Table 1, each of the solid electrolytic capacitors of Examples 1 to 6 according to the present invention has a smaller ESR than the solid electrolytic capacitor of Comparative Example 1. Therefore, according to the present invention, the anode is immersed in a solution containing a coupling agent having at least two phosphonic acid groups, and the anode is subjected to electrolytic conversion treatment to form a coupling agent layer. The adhesion of the molecular layer and / or the adhesion of the conductive polymer layer to the conductive polymer layer can be further strengthened, and the contact resistance between the dielectric layer and the conductive polymer layer and / or the conductive polymer The contact resistance between the layer and the conductive polymer layer can be reduced, and the ESR can be reduced.

  When Example 1 and Example 3 are compared, Example 3 in which the first coupling agent layer is formed between the dielectric layer 2 and the first conductive polymer layer 4 has the first conductivity. The ESR is reduced as compared with Example 1 in which the second coupling agent layer 8 is formed between the polymer layer 4 and the second conductive polymer layer 5. From this, it is considered that the effect of reducing the contact resistance by improving the adhesion between the dielectric layer and the conductive polymer layer is greater than that between the conductive polymer layer and the conductive polymer layer.

  Further, from the comparison between Example 5 and Example 1 and Example 3, the first coupling agent layer 3 is formed between the dielectric layer 2 and the first conductive polymer layer 4, and By forming the second coupling agent layer 8 between the first conductive polymer layer 4 and the second conductive polymer layer 5, ESR can be further reduced.

  From the comparison between Example 1 and Example 2, the comparison between Example 3 and Example 4, and the comparison between Example 5 and Example 6, an electrolytic solution containing phosphoric acid was used as the electrolytic solution used for the electrolytic conversion treatment. The ESR is reduced when used. This is because by using an electrolyte containing phosphoric acid, the amount of coupling agent consumed for electrolytic formation is reduced, and more coupling agent is used for forming the coupling agent layer. Seem. Thereby, the coverage of the conductive polymer layer 4 with respect to the dielectric layer 2 is increased, and the adhesion of the conductive polymer layer to the dielectric layer and the adhesion of the conductive polymer layer to the conductive polymer layer are improved. It is considered that the contact resistance between the dielectric layer and the conductive polymer layer, and between the conductive polymer layer and the conductive polymer layer is reduced, and the ESR is reduced.

  From the comparison between Example 6 and Examples 1 to 5, the first coupling agent layer 3 is formed between the dielectric layer 2 and the first conductive polymer layer 4, and the first conductive high By forming a second coupling agent layer 8 between the molecular layer 4 and the second conductive polymer layer 5 and using an electrolytic solution containing phosphoric acid as an electrolytic solution for electrolytic conversion treatment, ESR It can be seen that can be reduced most.

DESCRIPTION OF SYMBOLS 1 ... Anode 2 ... Dielectric layer 3 ... 1st coupling agent layer 4 ... 1st conductive polymer layer 5 ... 2nd conductive polymer layer 6 ... 3rd conductive polymer layer 7 ... Conductivity Polymer layer 8 ... second coupling agent layer 9 ... carbon layer 10 ... silver layer 11 ... cathode layer 12 ... anode lead

Claims (4)

Forming an anode;
The anode is subjected to electrolytic conversion treatment in a solution containing a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group to form a dielectric layer and a first coupling agent layer on the surface of the anode. And a process of
Forming a first conductive polymer layer on the first coupling agent layer;
And a step of forming a cathode layer on the first conductive polymer layer. The anode on which the first conductive polymer layer is formed is subjected to electrolytic conversion treatment in a solution containing the coupling agent, and a second coupling agent layer is formed on the first conductive polymer layer. Forming, and
Forming a second conductive polymer layer on the second coupling agent layer,
The method for producing a solid electrolytic capacitor according to claim 1, wherein the step of forming the cathode layer is a step of forming a cathode layer on the second conductive polymer layer. Forming an anode;
Forming a dielectric layer on the surface of the anode;
Forming a first conductive polymer layer on the dielectric layer;
The anode on which the first conductive polymer layer is formed is subjected to electrolytic conversion treatment in a solution containing a coupling agent in which two phosphonic acid groups are bonded via a hydrocarbon group, so that the first conductive high-molecular layer is formed. Forming a coupling agent layer on the molecular layer;
Forming a second conductive polymer layer on the coupling agent layer;
And a step of forming a cathode layer on the second conductive polymer layer. The method for producing a solid electrolytic capacitor according to claim 1, wherein the coupling agent is represented by the following general formula (1).

(Wherein R represents — (CH ₂ ) _n —, — (CH ₂ O) _n —, — (C ₂ H ₅ O) _n —, or —O— (CH ₂ ) _n —O—, n represents an integer of 1 to 18.)

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