JP5502562B2 - Manufacturing method of solid electrolytic capacitor - Google Patents

Description

  The present invention relates to a method for manufacturing a solid electrolytic capacitor, and more particularly to a method for manufacturing a solid electrolytic capacitor having high withstand voltage performance.

  Conventionally, a solid electrolytic capacitor having a conductive polymer layer as an electrolyte is widely known as a capacitor suitable for miniaturization. Such a solid electrolytic capacitor includes at least a capacitor element having an anode body having a dielectric film formed on the surface of a base material and a conductive polymer layer formed on the surface of the anode body.

  As a base material, what etched the metal plate or metal foil of the valve metal, or what sintered the molded object of the valve metal powder can be used. The anode body can be formed by subjecting the surface of the base material to a chemical conversion treatment and forming a dielectric film on the surface of the base material. The chemical conversion treatment is a treatment in which the surface of the base material is electrolytically oxidized using a chemical conversion liquid, and is a method widely used for forming a dielectric coating. Examples of the chemical conversion liquid include an aqueous solution containing a chemical conversion accelerator, and examples of the chemical conversion accelerator include phosphoric acid, nitric acid, and sulfuric acid. In particular, a phosphoric acid aqueous solution tends to be used in the manufacturing process of a solid electrolytic capacitor (Patent Document 1).

  By the way, it is known that when a chemical conversion treatment is performed using the chemical conversion liquid, hydroxide ions generated in the chemical conversion liquid to which a voltage is applied are involved in the formation of the dielectric film. However, since the base material has a shape having fine irregularities on the surface, such as a metal plate and metal foil whose surface is etched, or a sintered body, a substance containing oxygen elements such as hydroxide ions May not be sufficiently supplied to the depth of the recess, resulting in a non-uniform dielectric coating.

  The dielectric coating is one of the factors that influence the performance of the solid electrolytic capacitor. For example, when the dielectric coating is not uniform, the withstand voltage performance of the solid electrolytic capacitor is lowered and the leakage current is increased. For this reason, the dielectric coating is required to have a shape that uniformly covers the entire surface of the substrate. Therefore, Patent Document 2 proposes a method of uniformly forming a dielectric coating by adding hydrogen peroxide to a phosphoric acid aqueous solution that is a chemical conversion solution.

JP 2003-338432 A Japanese Patent Laid-Open No. 9-306791

  However, the demand for higher performance of solid electrolytic capacitors is still increasing, and further technology development is required. Therefore, in view of the above circumstances, an object of the present invention is to provide a method for producing a high-performance solid electrolytic capacitor having high withstand voltage performance.

  The present invention is a solid comprising a capacitor element having a valve metal as a base material, an anode body having a dielectric film formed on the surface of the base material, and a conductive polymer layer formed on the surface of the anode body. A method for manufacturing an electrolytic capacitor, comprising: forming a dielectric film on a surface of a base material by subjecting the base material to a chemical conversion treatment using a chemical conversion liquid to which phosphoric acid, sulfuric acid and hydrogen peroxide are added; And a step of forming a conductive polymer layer on the body film.

  In the method for producing a solid electrolytic capacitor, the ratio of the mass% of phosphoric acid (A), the mass% of sulfuric acid (B), and the mass% of hydrogen peroxide (C) added to the chemical conversion liquid is A: B. : C = 1: 0.5-10: 1-20 are preferable.

  In the method for manufacturing a solid electrolytic capacitor, the mass% (C) of the hydrogen peroxide added to the chemical conversion liquid is preferably 0.01% by mass or more and 20% by mass or less.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a high performance solid electrolytic capacitor with a high withstand voltage performance can be provided.

It is sectional drawing which shows typically a preferable example of the structure of the solid electrolytic capacitor applied to the manufacturing method which concerns on this invention. It is a schematic diagram which shows an example of a preferable aspect when performing a chemical conversion treatment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated. Note that the dimensional relationships such as length, size, and width in the drawings are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensions.

In this specification, the mass% of phosphoric acid in the chemical conversion liquid means the mass% of added H ₃ PO ₄ with respect to the total mass of the chemical conversion liquid prepared by adding phosphoric acid, sulfuric acid and hydrogen peroxide. Say. Similarly, the mass% of sulfuric acid and the mass% of hydrogen peroxide in the chemical conversion liquid are the mass of H ₂ SO ₄ added to the total mass of the chemical conversion liquid prepared by adding phosphoric acid, sulfuric acid and hydrogen peroxide. % And the mass% of added H ₂ O ₂ .

  FIG. 1 is a cross-sectional view schematically showing a preferred example of the structure of a solid electrolytic capacitor applied to the manufacturing method according to the present invention. A preferred example of the method for producing a solid electrolytic capacitor according to the present invention will be described below with reference to FIG.

<Formation of dielectric coating> (dielectric coating forming step)
The dielectric film 12 is formed on the surface of the substrate by subjecting the substrate 10 to a chemical conversion treatment using a chemical conversion solution containing phosphoric acid, sulfuric acid and hydrogen peroxide. By this step, the anode body 13 is produced.

≪Preparation of base material≫
In the present embodiment, the base material 10 is made of a sintered body, and as shown in FIG. 1, a rod-shaped anode lead 11 is erected. Such a base material 10 is formed, for example, by molding the powder into a desired shape in a state where one end side in the longitudinal direction of the anode lead 11 of the rod-shaped body is embedded in the valve action metal powder, and then firing the molded body. It can be formed by tying. As the valve metal, tantalum, niobium, titanium, aluminum or the like can be used. Moreover, although the anode lead 11 can be comprised with a metal, especially a valve metal can be used suitably.

<< Preparation of chemical conversion liquid >>
In the present invention, the chemical conversion solution used for the chemical conversion treatment is an aqueous solution containing phosphoric acid, sulfuric acid and hydrogen peroxide. This indicates that, as a result of intensive studies by the inventor, when a chemical conversion treatment is performed using a chemical conversion liquid having this composition, the leakage current of the anode body 13 decreases and the withstand voltage increases. Has been reached. In particular, the mass% (A) of phosphoric acid, the mass% (B) of sulfuric acid, and the mass% (C) of hydrogen peroxide in the chemical conversion liquid are A: B: C = 1: 0.5 to 10: 1. It has been found that 20 is preferable. Such a chemical conversion liquid can be prepared, for example, by adding a phosphoric acid aqueous solution, concentrated sulfuric acid, and a hydrogen peroxide aqueous solution to water as a solvent.

  It is preferable that the mass% (A) of phosphoric acid in a chemical conversion liquid is 0.01 mass% or more and 1 mass% or less. Moreover, it is preferable that the mass% (B) of the sulfuric acid in a chemical conversion liquid is 0.005 mass% or more and 10 mass% or less. Moreover, it is preferable that the mass% (C) of hydrogen peroxide in a chemical conversion liquid is 0.01 mass% or more and 20 mass% or less. When phosphoric acid, sulfuric acid, or hydrogen peroxide is added within the above range, the oxidation reaction during the chemical conversion treatment can be easily controlled, and the quality of the dielectric film 12 can be improved. Therefore, the withstand voltage performance of the solid electrolytic capacitor can be further improved, and the leakage current can be reduced.

≪Chemical conversion treatment≫
FIG. 2 is a schematic diagram showing an example of a preferable mode when performing the chemical conversion treatment. In FIG. 2, the treatment bath 31 is filled with the chemical conversion liquid 32 prepared as described above. In the chemical liquid 32, the base material 10 connected to the positive electrode side of the DC power source 33 and the cathode piece 34 connected to the negative electrode side of the DC power source 33 are immersed. When a voltage is applied to the base material 10 from the DC power source 33, the dielectric coating 12 is formed on the surface of the base material 10, and the anode body 13 is produced. In addition, as shown in FIG. 2, the base material 10 can be easily made into the positive electrode by electrically connecting the anode lead 11 and the DC power source 33.

<Formation of conductive polymer layer> (Conductive polymer layer forming step)
Next, a conductive polymer layer 14 is formed on the dielectric coating 12. By this step, the anode body 13 is covered with the conductive polymer layer 14, and the capacitor element 15 is manufactured.

  The conductive polymer layer 14 can be formed by, for example, known chemical polymerization. Chemical polymerization includes a gas phase polymerization method and a liquid phase polymerization method. The gas phase polymerization method is a method using a gas containing a monomer that is a basic skeleton of a conductive polymer layer. On the other hand, the liquid phase polymerization method is a method using a polymerization solution containing a monomer. In any method, the conductive polymer layer 14 can be formed by chemically polymerizing a monomer on the dielectric coating 12. As a material for imparting conductivity to the monomer polymer, a known dopant can be used, and naturally, an oxidizing agent that promotes chemical polymerization may be used.

  The conductive polymer layer 14 may be formed by known electrolytic polymerization. For example, the conductive polymer layer 14 can be formed by immersing the anode body 13 in a polymerization solution containing a monomer and a dopant and electrolytically polymerizing the monomer in the polymerization solution on the surface of the anode body 13. Furthermore, the conductive polymer layer 14 may be formed using both chemical polymerization and electrolytic polymerization. In particular, after the inner layer of the conductive polymer layer is formed on the dielectric coating 12 by chemical polymerization and then the outer layer of the conductive polymer layer is formed by electrolytic polymerization, the conductivity is high and the ESR is low. The conductive polymer layer 14 can be formed.

  As a monomer constituting the basic skeleton of the conductive polymer layer 14, at least one of an aliphatic compound, an aromatic compound, a heterocyclic compound, and a heteroatom-containing compound can be used. Of these, thiophene and its derivatives, pyrrole and its derivatives, aniline and its derivatives, and furan and its derivatives are preferable. This is because the conductive polymer layer obtained by polymerizing these monomers can form a thin film and is excellent in conductivity. In particular, pyrrole and derivatives thereof can be preferably used. Examples of thiophene derivatives include 3,4-ethylenedioxythiophene and 3-alkylthiophene. Examples of pyrrole derivatives include N-methylpyrrole. Examples of aniline derivatives include N, N-dimethylaniline and N-alkyl. There are anilines.

  As the oxidizing agent, known oxidizing agents can be used, and examples thereof include hydrogen peroxide, permanganic acid, hypochlorous acid, and chromic acid. As a dopant, a well-known dopant can be used, For example, the acid or salt of sulfuric acid compounds, such as alkylsulfonic acid, aromatic sulfonic acid, and polycyclic aromatic sulfonic acid, a sulfuric acid, nitric acid etc. can be mentioned. Moreover, you may use well-known oxidizing agent and dopant materials, such as a sulfonic acid metal salt, which have the function of an oxidizing agent and the function of a dopant.

<Encapsulation of capacitor element> (Sealing process)
Next, a cathode layer composed of a carbon layer 16 and a silver paste layer 17 is formed on the conductive polymer layer 14 (see FIG. 1). The carbon layer 16 as the cathode lead layer only needs to have conductivity, and can be formed using, for example, graphite. The carbon layer 16 and the silver paste layer 17 can be formed using a known technique.

  Then, the anode terminal 18 is connected to the exposed end of the anode lead 11, an adhesive layer 19 is formed on the silver paste layer 17, and one end of the cathode terminal 20 is connected. As shown in FIG. Sealed with resin 21. Finally, the anode terminal 18 and the cathode terminal 20 exposed to the outside of the exterior resin 21 are bent along the exterior resin 21 and then subjected to an aging process, whereby the solid electrolytic capacitor 100 shown in FIG. 1 is completed. In addition, the anode terminal 18 and the cathode terminal 20 can be comprised, for example with metals, such as copper or a copper alloy, and an epoxy resin can be used as a raw material of the exterior resin 21, for example.

  According to the method for producing a solid electrolytic capacitor according to the present invention described in detail above, an anode body having a small leakage current and a high withstand voltage can be produced, and thus a solid electrolytic capacitor having a high withstand voltage performance is produced. Can do.

  The solid electrolytic capacitor according to the present invention is not limited to the solid electrolytic capacitor according to the above-described embodiment, and can be applied to other known solid electrolytic capacitors having a dielectric film. Specific examples of other known solid electrolytic capacitors include a wound solid electrolytic capacitor and a laminated solid electrolytic capacitor using a valve metal plate.

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

<Example 1>
≪Dielectric film formation process≫
First, a tantalum powder was prepared using a known method, and the tantalum powder was formed into a rectangular parallelepiped with one end of the tantalum wire embedded in the tantalum powder. Then, by sintering this, a base material in which one end of the anode lead was embedded was formed. The dimensions of the substrate at this time were 1.7 mm × 2.0 mm × 1.0 mm in length × width × height.

  Next, 1000 g of an aqueous solution to which 0.2 g, 0.2 g, and 0.6 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added as a chemical conversion solution was prepared. Specifically, 0.236 g of 85% by mass phosphoric acid aqueous solution, 0.206 g of 97% concentrated sulfuric acid, and 1.936 g of 31% hydrogen peroxide aqueous solution were added to 500 g of water, and water was further added. The total aqueous solution was adjusted to 1000 g to prepare the aqueous solution. The addition amounts of phosphoric acid, sulfuric acid and hydrogen peroxide in the chemical conversion liquid at this time were 0.02 mass%, 0.02 mass% and 0.06 mass%.

And the prepared chemical conversion liquid was heated at 60 degreeC, the base material 10 was immersed in this heated chemical conversion liquid, and the voltage of 20V was applied for 5 hours. By this step, a dielectric film made of Ta ₂ O ₅ was formed on the surface of the base material, and an anode body was produced. In addition, with respect to some of the produced some anode bodies, the subsequent process was not performed but it used for the measurement of withstand voltage and leakage current.

≪Conductive polymer layer formation process≫
Next, an inner layer of the conductive polymer layer was formed on the dielectric film by a liquid phase polymerization method. Specifically, first, an ethanol solution containing pyrrole at a concentration of 3 mol / L and an aqueous solution containing 0.1 mol / L and 1 mol / L of ammonium persulfate and alkylnaphthalenesulfonic acid were prepared. Then, after immersing the anode body in the ethanol solution adjusted to 25 ° C. for 5 minutes, and subsequently immersing the anode body in the aqueous solution adjusted to 25 ° C. for 5 minutes to chemically polymerize pyrrole, An inner layer of the conductive polymer layer was formed. Thereafter, the anode body was pulled up from the aqueous solution and dried.

  Next, the outer layer of the conductive polymer layer was formed on the inner layer of the conductive polymer layer by electrolytic polymerization. Specifically, the anode body is immersed in an aqueous solution containing 0.1 mol / L each of pyrrole and alkylnaphthalene sulfonic acid, and a current of 1 mA is applied to the inner layer of the conductive polymer layer formed on the surface of the anode body. Was energized for 2 hours to form an outer layer of the conductive polymer layer. By this step, a conductive polymer layer was formed, and a capacitor element was produced.

≪Sealing process≫
After completion of the above operation, the anode body was pulled up from the aqueous solution, washed with water, then placed in a dryer at 100 ° C. and dried. And the carbon layer was formed by apply | coating a graphite particle suspension to the capacitor | condenser element after drying, and making it dry in air | atmosphere, Furthermore, the silver paste layer was formed according to the well-known technique.

  Then, an anode terminal made of copper was welded to the anode lead, a silver adhesive was applied onto the silver paste layer to form an adhesive layer, and one end of the cathode terminal made of copper was adhered to the adhesive layer. Further, the capacitor element was sealed with an exterior resin made of an epoxy resin so that part of the anode terminal and the cathode terminal was exposed. Finally, the exposed anode terminal and cathode terminal were bent along the exterior resin, and then an aging treatment was performed. The manufactured solid electrolytic capacitor had a rated voltage of 6.3 V, a rated capacity of 150 μF, and a length × width × height of 2.8 mm × 3.5 mm × 2.0 mm.

<Example 2>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.5 g, 0.5 g, and 1.5 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added was used. did. That is, in Example 2, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.05% by mass, 0.05% by mass, and 0.15% by mass, respectively.

<Comparative Example 1>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.4 g of phosphoric acid was added was used, and a solid electrolytic capacitor was further produced. That is, in Comparative Example 1, an aqueous solution having a phosphoric acid addition amount of 0.04% by mass was used as the chemical conversion solution.

<Comparative example 2>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.4 g of sulfuric acid was added was used, and a solid electrolytic capacitor was further produced. That is, in Comparative Example 2, an aqueous solution having an addition amount of sulfuric acid of 0.04% by mass was used as the chemical conversion solution.

<Comparative Example 3>
In the chemical conversion treatment, an anode body was prepared in the same manner as in Example 1, except that a 1000 g aqueous solution containing 0.2 g phosphoric acid and 0.6 g hydrogen peroxide was used. Produced. That is, in Comparative Example 3, an aqueous solution in which the addition amounts of phosphoric acid and hydrogen peroxide were 0.02 mass% and 0.06 mass% was used as the chemical conversion liquid.

<Performance evaluation>
≪Anode body withstand voltage test≫
Eight from each of the anode bodies after chemical conversion prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were selected, immersed in a 0.02 mass% phosphoric acid aqueous solution, and a current value of 0.01 A. A voltage was applied to the anode body in a constant state. The voltage when the voltage became stable and constant was taken as the withstand voltage, and the average values of Examples 1 and 2 and Comparative Examples 1 to 3 were calculated. The results are shown in “Withstand voltage (V) of anode body” in Table 1.

≪Measurement of leakage current of anode body≫
Eight from each anode body produced in Examples 1 and 2 and Comparative Examples 1 to 3 was selected, immersed in a 0.02 mass% phosphoric acid aqueous solution, and a voltage of 6.3 V was applied for 120 seconds. did. After the application, the amount of leakage current of each anode body was measured, and the average value of Example 1 and Comparative Examples 1 to 3 was calculated. The results are shown in “LC of anode body (μA)” in Table 1.

≪Withstand voltage test of solid electrolytic capacitor≫
Eight out of the solid electrolytic capacitors prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were selected, and the withstand voltage test was performed by increasing the applied DC voltage at a rate of 1 V / second. The voltage when the leakage current was 1 mA or more was taken as the withstand voltage, and the average values of Examples 1 and 2 and Comparative Examples 1 to 3 were calculated. The results are shown in “Withstand voltage (V) of solid electrolytic capacitor” in Table 1.

≪Measurement of leakage current of solid electrolytic capacitor≫
Eight from each of the solid electrolytic capacitors produced in Examples 1 and 2 and Comparative Examples 1 to 3 were selected, and a rated voltage was applied for 2 minutes. After the application, the amount of leakage current of each solid electrolytic capacitor was measured, and the average values in Examples 1 and 2 and Comparative Examples 1 to 3 were calculated. The results are shown in “LC (μA) of solid electrolytic capacitor” in Table 1.

  In Table 1, the withstand voltage of the anode body of Example 1 is larger than the withstand voltage of the anode body of Comparative Example 1, and the leakage current of the anode body of Example 1 is larger than the leakage current of the anode body of Comparative Example 1. It was small. In Table 1, the solid electrolytic capacitor of Example 1 also had a higher withstand voltage and a smaller leakage current than the solid electrolytic capacitor of Comparative Example 1. From this result, it can be seen that the difference in withstand voltage performance of the solid electrolytic capacitor is caused by the difference in performance of the anode body.

  Comparing Example 1 and Comparative Example 2, it was found that the anode body and the solid electrolytic capacitor of Example 1 had higher withstand voltage and smaller leakage current. From this result, it can be seen that a high-performance solid electrolytic capacitor as in Example 1 cannot be produced using a chemical conversion solution containing sulfuric acid.

  By comparing Example 1 with Comparative Examples 1 and 2, the reason why a high-performance solid electrolytic capacitor as in Example 1 is obtained is not only due to the total amount of the chemical conversion accelerator in the chemical conversion liquid. I understood. That is, it was found that in the chemical conversion treatment, not only phosphoric acid and sulfuric acid but also hydrogen peroxide contributes to the oxidation of the dielectric film, thereby improving the withstand voltage performance of the solid electrolytic capacitor.

  Further, even when Example 1 was compared with Comparative Example 3, it was found that the anode body and the solid electrolytic capacitor of Example 1 had a higher withstand voltage and a smaller leakage current. From this result, even if a chemical solution containing phosphoric acid and hydrogen peroxide was used, a high performance solid electrolytic capacitor as in Example 1 could not be produced, and three additions of phosphoric acid, sulfuric acid and hydrogen peroxide were added. I found out that I needed something.

  Moreover, when Example 1 and 2 were seen, compared with Comparative Examples 1-3, in any case, the withstand voltage of the manufactured anode body and the solid electrolytic capacitor was large, and the leakage current was small. That is, even if the concentration of each substance is increased or decreased, it has been found that a high-performance solid electrolytic capacitor can be manufactured if the mixing ratio of each substance is the same.

  Next, a study was conducted focusing on the mixing ratio of phosphoric acid, sulfuric acid and hydrogen peroxide in the chemical conversion solution.

<Example 3>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.2 g, 0.1 g, and 0.2 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added was used. did. That is, in Example 3, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.01 mass%, and 0.02 mass%.

<Example 4>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.2 g, 2 g, and 4 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added was used. That is, in Example 4, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.2 mass%, and 0.4 mass%.

<Example 5>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.2 g, 0.1 g, and 4 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added, respectively. That is, in Example 5, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02% by mass, 0.01% by mass, and 0.4% by mass.

<Example 6>
An anode body was produced in the same manner as in Example 1 except that in the chemical conversion treatment, 1000 g of an aqueous solution to which 0.2 g, 2 g, and 0.2 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added, respectively. That is, in Example 6, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.2 mass%, and 0.02 mass%, respectively.

<Comparative Example 4>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.2 g, 0.02 g, and 0.2 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added was used. did. That is, in Comparative Example 4, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.002 mass%, and 0.02 mass%.

<Comparative Example 5>
An anode body was produced in the same manner as in Example 1 except that in the chemical conversion treatment, 1000 g of an aqueous solution to which 0.2 g, 0.02 g, and 4 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added, respectively. That is, in Comparative Example 5, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.002 mass%, and 0.4 mass%.

<Comparative Example 6>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.2 g, 4 g, and 0.2 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added, respectively. That is, in Comparative Example 6, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.4 mass%, and 0.02 mass%.

<Comparative Example 7>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.2 g, 4 g, and 4 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added, respectively. That is, in Comparative Example 7, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.4 mass%, and 0.4 mass%.

<Comparative Example 8>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.2 g, 0.1 g, and 0.1 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added was used. did. That is, in Comparative Example 8, the respective addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02% by mass, 0.01% by mass, and 0.01% by mass.

<Comparative Example 9>
An anode body was produced in the same manner as in Example 1 except that in the chemical conversion treatment, 1000 g of an aqueous solution to which 0.2 g, 0.1 g, and 6 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added, respectively. That is, in Comparative Example 9, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02% by mass, 0.01% by mass, and 0.6% by mass.

<Comparative Example 10>
An anode body was produced in the same manner as in Example 1 except that in the chemical conversion treatment, 1000 g of an aqueous solution to which 0.2 g, 2 g, and 0.1 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added, respectively. That is, in Comparative Example 10, the respective addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.2 mass%, and 0.01 mass%.

<Comparative Example 11>
In the chemical conversion treatment, an anode body was produced in the same manner as in Example 1 except that 1000 g of an aqueous solution to which 0.2 g, 2 g, and 6 g of phosphoric acid, sulfuric acid, and hydrogen peroxide were added was used. That is, in Comparative Example 11, the addition amounts of phosphoric acid, sulfuric acid, and hydrogen peroxide in the chemical conversion liquid were 0.02 mass%, 0.2 mass%, and 0.6 mass%.

<Performance evaluation>
Using the anode bodies manufactured in Examples 3 to 6 and Comparative Examples 4 to 11, a withstand voltage test and a leakage current measurement were performed in the same manner as described above. The results are shown in Table 2. Table 2 also shows the contents of phosphoric acid, sulfuric acid and hydrogen peroxide in each chemical conversion liquid, the mass% of phosphoric acid, sulfuric acid and hydrogen peroxide as “mass% of phosphoric acid: mass% of sulfuric acid: peroxidation”. It was described in “mass% of hydrogen”. Further, the content ratio of phosphoric acid, sulfuric acid and hydrogen peroxide in the chemical conversion liquid is shown in parentheses.

  From Table 2, compared with the anode body of each Example, the solid electrolytic capacitor of each comparative example resulted in a small withstand voltage and a large leakage current. From these results, it was found that the ratio of the addition amounts of phosphoric acid, sulfuric acid and hydrogen peroxide added to the chemical conversion solution is preferably 1: 0.5 to 10: 1 to 20.

  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 widely used in the production of solid electrolytic capacitors.

  DESCRIPTION OF SYMBOLS 10 Base material, 11 Anode lead, 12 Dielectric film, 13 Anode body, 14 Conductive polymer layer, 15 Capacitor element, 16 Carbon layer, 17 Silver paste layer, 18 Anode terminal, 19 Adhesive layer, 20 Cathode terminal, 21 Outer layer resin, 31 treatment bath, 32 chemical conversion liquid, 33 DC power supply, 34 cathode piece, 100 solid electrolytic capacitor.

Claims (2)

A solid electrolytic capacitor comprising a capacitor element having a valve metal as a base material, an anode body having a dielectric film formed on the surface of the base material, and a conductive polymer layer formed on the surface of the anode body. A manufacturing method comprising:
Forming a dielectric film on the surface of the base material by subjecting the base material to a chemical conversion treatment using a chemical conversion liquid to which phosphoric acid, sulfuric acid and hydrogen peroxide have been added; and
Have a, a step of forming a conductive polymer layer on the dielectric film,
The ratio of the phosphoric acid mass% (A), the sulfuric acid mass% (B), and the hydrogen peroxide mass% (C) added to the chemical conversion liquid is as follows: A: B: C = 1: The manufacturing method of the solid electrolytic capacitor which is 0.5-10: 1-20 . 2. The method for producing a solid electrolytic capacitor according to claim 1 , wherein a mass% (C) of the hydrogen peroxide added to the chemical conversion liquid is 0.01 mass% or more and 20 mass% or less.

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