JP2007115918A - Manufacturing method of solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a solid electrolytic capacitor capable of obtaining the solid electrolytic capacitor having good capacitor characteristics and reducing the ESR of the obtained solid electrolytic capacitor, while realizing the improvement of manufacturing efficiency by omitting re-conversion treatment. <P>SOLUTION: This manufacturing method of the solid electrolytic capacitor comprises the steps of forming a solid electrolytic layer by supplying a polymeric liquid containing a monomer constituting an electrically conductive polymer, a proton donating polymer, and a water soluble polymer onto the surface of a valve metal substrate constituted using a valve action metal on its surface including an exposed part wherein a dielectric layer is not formed, and polymerizing the monomer in the polymeric liquid to form the solid electrolytic layer, repairing for forming a dielectric layer in at least the exposed part, and forming a conductor layer on the solid electrolytic layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a solid electrolytic capacitor.

  In recent years, digitization, downsizing, and speeding up of electronic devices have been increasingly accelerated. Under such circumstances, an electrolytic capacitor that is one of the electronic components suitable for high frequency applications frequently used in various electronic devices is required to have a larger capacity and a lower impedance during high frequency operation than ever before. At the same time, reduction of equivalent series resistance (ESR), improvement of operational stability, improvement of reliability, and further life extension are desired.

  Electrolytic capacitors generally include so-called valve action metals such as aluminum and tantalum, a dielectric layer made of an oxide film formed by anodizing the surface, an electrolyte layer, and a conductor made of graphite, silver, or the like. The layers are sequentially stacked.

  Such electrolytic capacitors are roughly classified into two types, liquid electrolytic capacitors and solid electrolytic capacitors, depending on the properties of the electrolyte material. The former includes an electrolyte layer containing a liquid electrolyte (electrolytic solution) as an electrolyte material, and the latter includes an electrolyte layer containing a solid electrolyte (complex salt, conductive polymer, etc.) as an electrolyte material. It is. Comparing these from the viewpoints of various characteristics, the former is inherently likely to cause deterioration over time due to leakage or evaporation (dry up) of the electrolyte, whereas the latter has almost no such fear.

  Based on these advantages, research and development of solid electrolytic capacitors has been actively carried out recently. In particular, from the viewpoint of leakage current value, impedance characteristics, heat resistance, etc., the focus of development and practical application is manganese dioxide and complex salts. Is rapidly changing from those using a conjugated conductive polymer doped with an electron donating or electron withdrawing substance (dopant) to polypyrrole, polythiophene, or the like.

  As such a solid electrolytic capacitor, when manufacturing a solid electrolytic capacitor using a chemical conversion foil (a valve-acting metal surface formed with an oxide film), the foil is cut into a desired shape. The working metal material itself is exposed. And in order to form an oxide film in this exposed part, the re-chemical conversion process is performed (for example, refer patent document 1). However, by performing this re-chemical conversion treatment, the number of manufacturing steps increases, and the manufacturing efficiency decreases.

On the other hand, when a solid electrolyte layer is formed without forming an oxide film on the exposed part by re-chemical conversion treatment, the leakage current increases. There arises a problem that a solid electrolytic capacitor cannot be obtained.
JP 2003-109852 A

  The present inventor has been made in view of the above-mentioned problems of the prior art, and can achieve a solid electrolytic capacitor having good capacitor characteristics while realizing improvement in manufacturing efficiency by omitting the re-forming process, Furthermore, it aims at providing the manufacturing method of the solid electrolytic capacitor which can reduce ESR of the solid electrolytic capacitor obtained.

  In order to achieve the above object, the present invention provides a monomer that constitutes a conductive polymer on a surface of a valve metal substrate that is configured using a valve metal, including an exposed portion where a dielectric layer is not formed, A solid electrolyte layer forming step of supplying a polymerization liquid containing a proton-donating polymer and a water-soluble polymer and polymerizing the monomer in the polymerization liquid to form a solid electrolyte layer; and a dielectric layer at least on the exposed portion. There is provided a method for producing a solid electrolytic capacitor comprising: a repairing step to be formed; and a conductor layer forming step of forming a conductor layer on the solid electrolyte layer.

  According to the production method of the present invention, the specific polymerization solution is used as a polymerization solution for forming the solid electrolyte layer, and after the formation of the solid electrolyte layer, the repairing step is performed, whereby the exposed portion is removed. Without performing a re-forming process, it is possible to form a dielectric layer on the exposed portion in the solid electrolyte layer forming step and the repairing step, thereby reducing leakage current. Therefore, it is possible to manufacture a solid electrolytic capacitor having good capacitor characteristics while realizing an improvement in manufacturing efficiency by omitting the re-forming process. Furthermore, according to the production method of the present invention, the solid solution obtained by supplying the polymerization solution without performing re-chemical conversion treatment on the exposed portion to form a solid electrolyte layer, and then performing a repairing step. It is possible to reduce the ESR of the electrolytic capacitor. In the present invention, as the valve metal substrate, a solid valve metal having no dielectric layer formed may be used.

  Further, in the method for producing a solid electrolytic capacitor of the present invention, before the solid electrolyte layer forming step, the valve action metal having a dielectric layer formed on the surface is cut, and the solid electrolyte layer is formed in the region where the solid electrolyte layer is to be formed. The method further includes a cutting step for obtaining the valve metal base body having the exposed portion where the dielectric layer is not formed, and after the cutting step, without performing a chemical conversion treatment for forming the dielectric layer on the exposed portion, The solid electrolyte layer forming step is preferably performed.

  Normally, when manufacturing a solid electrolytic capacitor, a valve metal substrate is obtained by cutting a chemical conversion foil formed by forming an oxide film on the surface of a valve action metal into a desired shape. Solid electrolytic process with good capacitor characteristics while realizing improvement in manufacturing efficiency by performing solid electrolyte layer formation process and repair process without performing chemical conversion treatment (re-chemical conversion treatment) A capacitor can be obtained, and the ESR of the obtained solid electrolytic capacitor can be reduced.

  In the method for producing a solid electrolytic capacitor of the present invention, the proton donating polymer preferably has a perfluoroalkyl ether side chain containing a sulfonic acid group.

  By using such a proton-donating polymer, it becomes possible to more efficiently form a dielectric layer on the exposed portion in the repairing step after the formation of the solid electrolyte layer, and the ESR of the obtained solid electrolytic capacitor can be reduced. It becomes possible to reduce more sufficiently.

  In the method for producing a solid electrolytic capacitor of the present invention, the water-soluble polymer is preferably polyvinyl alcohol.

  Such a water-soluble polymer functions well as a medium for dispersing the proton-donating polymer, so that the dispersibility of the proton-donating polymer can be improved, and the proton-donating polymer is highly dispersed in the solid electrolyte layer. It is possible to exist in a state. As a result, in the repair process after the formation of the solid electrolyte layer, it is possible to more efficiently form the dielectric layer on the exposed portion, and to further sufficiently reduce the ESR of the obtained solid electrolytic capacitor. It becomes possible.

  According to the present invention, it is possible to obtain a solid electrolytic capacitor having good capacitor characteristics while omitting the re-forming process and improving the manufacturing efficiency, and to further reduce the ESR of the obtained solid electrolytic capacitor. A manufacturing method of a possible solid electrolytic capacitor can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as the case may be. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Also, the positional relationship such as up / down / left / right is based on the positional relationship of the drawings.

  FIG. 1 is a diagram schematically showing a cross-sectional structure of a solid electrolytic capacitor obtained by a manufacturing method according to a preferred embodiment.

  The solid electrolytic capacitor 1 has a configuration in which a plurality (four in this case) of capacitor elements 2 are mounted and fixed on a substrate 20. Although not shown, in the solid electrolytic capacitor 1, the periphery of the multilayer structure composed of the capacitor elements 2 is molded with resin in order to protect the capacitor element 2 from oxygen, humidity, contact, and the like.

  Each capacitor element 2 has an anode part 5, a cathode part 6, and a resist part 7 that electrically insulates them. In the solid electrolytic capacitor 1, four capacitor elements 2 are connected to the respective anode elements. The part 5, the cathode part 6, and the resist part 7 are laminated so as to be at the same position when viewed from the lamination direction. Adjacent capacitor elements 2 are bonded to each other at the cathode portion 6 of each capacitor element 2 via a conductive adhesive 17 and are electrically connected to each other.

  The anode part 5 in the capacitor element 2 is composed of a foil-like or plate-like valve action metal 9 and has a shape drawn from the inside of the cathode part 6. The cathode portion 6 is provided so as to cover the periphery of the valve metal 9 excluding the drawn portion, and the dielectric layers 10 and 32 and the cathode 15 are laminated in order from the valve metal 9 side. It has a configuration. The valve metal base 16 is formed by the valve action metal 9 and the dielectric layers 10 and 32. Further, the valve metal base 16 has an exposed portion 31 before the formation of the solid electrolyte layer 11, and a dielectric layer 32 is formed so as to cover the exposed portion 31 through a solid electrolyte layer forming step and a repairing step. ing. The resist portion 7 is provided on the valve metal 9 along the boundary between the anode portion 5 and the cathode portion 6. The resist portion 7 is made of an insulating material, and is preferably made of a resin material such as an epoxy resin or a silicone resin.

  Here, the structure of the capacitor element 2 will be described in more detail with reference to FIG. FIG. 2 is a diagram schematically showing a cross-sectional structure of the main part of the capacitor element 2, and shows an enlarged view of the laminated structure of the valve action metal 9, the dielectric layer 10 and the cathode 15.

  As shown in the figure, the valve metal 9 functioning as an anode in the capacitor element 2 has a roughened surface, which increases the surface area. Here, examples of the constituent material of the valve metal 9 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Among these, aluminum or tantalum is preferable.

  The dielectric layers 10 and 32 have a very thin layered structure provided along the surface shape of the valve metal 9. Of these, the dielectric layer 10 is constituted by an oxide film formed by oxidizing the surface of the valve metal 9. In addition, the dielectric layer 32 is formed through a solid electrolyte layer forming step and a repairing step, and the structure thereof is not necessarily clear, but an oxide film formed by oxidizing the surface of the valve metal 9 or It is considered that the solid electrolyte layer 11 is made of an insulating material that is insulated.

  As shown in the figure, the cathode 15 has a structure in which a solid electrolyte layer 11 and a conductor layer 12 are laminated in order from the valve metal 9 side. The solid electrolyte layer 11 substantially functions as a cathode in the solid electrolytic capacitor. The solid electrolyte layer 11 contains a conductive polymer, a proton-donating polymer, and a water-soluble polymer, and the polymerization liquid containing the monomer, the proton-donating polymer, and the water-soluble polymer constituting the conductive polymer is used as a valve. It is a layer formed by supplying the solid electrolyte layer 11 of the metal substrate 16 to a site where the solid electrolyte layer 11 is to be formed and polymerizing the monomer in the polymerization solution.

  Here, as the conductive polymer, conductive polymers such as polyaniline, polypyrrole, polythiophene, polyfuran and derivatives thereof are preferable, and among these, poly (3,4-ethylenedioxythiophene) is more preferable. In addition, as a conductive polymer, what combined these 2 or more types may be used.

  The proton donating polymer is a so-called proton conducting polymer capable of donating a proton (moving the proton freely). This proton-donating polymer is, for example, one in which a side chain containing a functional group capable of donating protons (hereinafter referred to as “proton-donating functional group”) is bonded to a polymer skeleton as a main chain. The solid electrolyte layer 11 containing such a proton-donating polymer is excellent in the function of forming an oxide film again on the damaged portion when the adjacent dielectric layer 10 is damaged. However, the dielectric layer 10 can be repaired by itself (self-repairing). In the present invention, in particular, by forming the solid electrolyte layer 11 using a polymerization solution containing such a proton-donating polymer, an exposure in which the dielectric layer 10 is not formed in the valve metal substrate 16 in the subsequent repair process. The dielectric layer 32 can be formed on the portion 31.

  In the proton donating polymer, examples of the polymer skeleton as the main chain include polyfluoroethylene, polystyrene, poly (meth) acrylic acid (polyacrylic acid or polymethacrylic acid), polyimide, polyethylene, polypropylene, polybutadiene, and derivatives thereof. Etc. Examples of the proton-donating functional group include a sulfonic acid group, a phosphoric acid group, and a carboxyl group, and among these, a sulfonic acid group or a phosphoric acid group that is a relatively strong acid group is more preferable.

  Among the polymers having a polymer skeleton and a proton donating functional group as described above, polyfluoroethylene, polystyrene, poly (meth) acrylic acid, polyimide or a derivative thereof, or a phosphate group to which a sulfonic acid group is bonded. Poly (meth) acrylic acid or a derivative thereof in which is bonded is preferable.

  As the proton donating polymer, those having a perfluoroalkyl ether side chain containing a sulfonic acid group are more preferred, and polyfluoroethylene having a perfluoroalkyl ether side chain containing a sulfonic acid group and derivatives thereof are particularly preferred. This type of polyfluoroethylene is preferably a copolymer having a monomer unit of fluoroethylene and tetrafluoroethylene having a perfluoroalkyl ether side chain having a sulfonic acid group at the end. Specifically, for example, The compound which has a repeating unit represented by following formula (1) is mentioned.

  In formula (1), p is approximately 3 to 20, preferably 5 to 15, q is approximately 1 to 1000, preferably 1 to 500, m is approximately 1 to 5, preferably 1 to 3, and n is approximately 1 to 1. 5, preferably an integer from 1 to 3.

  The content of the proton donating polymer in the solid electrolyte layer 11 is preferably 0.01 to 50 parts by mass and preferably 0.1 to 45 parts by mass with respect to 100 parts by mass of the conductive polymer described above. More preferably, it is 0.2-40 mass parts. In addition, content here is a value based on the preparation amount at the time of forming the solid electrolyte layer 11, ie, the material input amount at the time of forming a conductive polymer. When the content of the proton donating polymer is within the above range, the above self-healing property is particularly good, and various characteristics (capacity, leakage current value, impedance characteristics, heat resistance, etc.) as a solid electrolytic capacitor are extremely high. It tends to be good.

  In the solid electrolyte layer 11, in addition to the proton donating polymer, a sulfonic acid compound such as sulfosalicylic acid, a phosphoric acid ester compound such as urea phosphate and mono n-butoxyethyl phosphate, maleic acid, Carboxylic acid compounds such as benzoic acid, p-nitrobenzoic acid, phthalic acid, and hydroxycarboxylic acid may be added. These additions tend to improve the self-repair function.

  The water-soluble polymer has water and can disperse the proton-donating polymer, and examples thereof include polyvinyl alcohol and cellulose.

  The content of the water-soluble polymer in the solid electrolyte layer 11 is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 45 parts by mass with respect to 100 parts by mass of the conductive polymer. It is especially preferable that it is 0.2-40 mass parts. The content of the water-soluble polymer is a value based on the charged amount when forming the solid electrolyte layer 11, that is, the material input amount when generating the conductive polymer, similarly to the content of the proton-donating polymer described above. It is. When the content of the water-soluble polymer is less than 0.01 parts by mass, the self-repair function tends to be insufficient as compared with the case where the content is in the above range. On the other hand, when the content exceeds 50 parts by mass, various characteristics (capacity, leakage current value, impedance characteristics, heat resistance, etc.) as a solid electrolytic capacitor are reduced as compared with the case where the content is within the above range. Tend.

  It is preferable that the solid electrolyte layer 11 further includes a dopant for increasing the conductivity of the conductive polymer. Examples of such a dopant include alkylbenzene sulfonic acid and its salt (for example, sodium paratoluene sulfonate), alkyl naphthalene sulfonic acid and its salt (for example, sodium isopropyl naphthalene sulfonate), and phosphoric acid.

  The conductor layer 12 has a two-layer structure in which a carbon paste layer 13 and a silver paste layer 14 are laminated in order from the solid electrolyte layer 11 side, and facilitates connection of the capacitor element 2 to the outside on the cathode side. Is provided.

  Hereinafter, the solid electrolytic capacitor 1 will be described with reference to FIG. 1 again. The substrate 20 is provided with an anode terminal 22a and a cathode terminal 24a on the side where the capacitor element 2 is mounted. The anode terminal 22a and the cathode terminal 24a are provided at positions corresponding to the anode part 5 and the cathode part 6 in the capacitor element 2 on the substrate 20, respectively.

  On the opposite side of the substrate 20 from the anode terminal 22a and the cathode terminal 24a, an anode terminal 22b and a cathode terminal 24b are provided at positions corresponding to these. The anode terminal 22a and the anode terminal 22b, and the cathode terminal 24a and the cathode terminal 24b on both surfaces of the substrate 20 are electrically connected to each other by a through hole 23 and a through hole 25 provided so as to penetrate the substrate 20, respectively. It has become a state.

  A resist portion 26 is formed between the anode terminal 22a and the cathode terminal 24a on the substrate 20, and a resist portion 28 is formed between the anode terminal 22b and the cathode terminal 24b. As a result, the anode terminals 22a and 22b and the cathode terminals 24a and 24b are insulated.

  In the solid electrolytic capacitor 1, the capacitor element 2 is placed on the substrate 20 as described below. That is, first, the cathode portion 6 of the capacitor element 2 is bonded to the cathode terminal 24a of the substrate 20 via the conductive adhesive 17, and is thereby electrically connected to each other.

  Further, the anode portion 5 in the capacitor element 2 is joined to the anode terminal 22a in the substrate 20 by a joint portion 30 provided by, for example, laser welding. Note that the anode portions 5 in each capacitor element are also bonded and bonded together by the bonding portion 30.

  Next, a preferred embodiment of a method for manufacturing the solid electrolytic capacitor 1 having the above-described configuration will be described with reference to FIG. FIG. 3 is a flowchart showing manufacturing steps of the solid electrolytic capacitor shown in FIG.

  First, in step S11, a sheet made of a valve metal is prepared, and this is subjected to chemical or electrochemical etching to form a large number of fine irregularities on the surface (surface expansion), and then these irregularities are formed. The formed surface is anodized to form a thin oxide film (corresponding to the dielectric layer 10 in FIG. 2) on the surface, and the obtained sheet is cut into a desired shape to obtain a valve metal substrate (FIG. 2 equivalent to the valve metal base 16). At this time, the dielectric layer 10 is formed in the region where the solid electrolyte layer of the obtained valve metal substrate 16 is to be formed by cutting the valve action metal having the dielectric layer formed on the surface into a desired shape. An exposed portion (corresponding to the exposed portion 31 in FIG. 2) is present. In the present invention, the surface of the valve metal may be enlarged and then cut into a desired shape without forming the dielectric layer 10 by anodic oxidation to form the valve metal substrate 16. In that case, the entire valve metal base body 16 becomes an exposed portion.

  In parallel with step S11, polymerization is performed by mixing the monomer constituting the conductive polymer, the proton donating polymer, the water-soluble polymer, the solvent, and the additive used as necessary. A liquid is prepared (step S13). Here, water, alcohol, etc. are used as a solvent, and ethanol, butanol, etc. are used as alcohol, for example. These solvents are used alone or in combination of two or more.

  Examples of the monomer constituting the conductive polymer include aniline, pyrrole, thiophene, furan, and derivatives thereof. By polymerizing these, polyaniline, polypyrrole, polythiophene, polyfuran, and derivatives thereof, etc. A conductive polymer can be obtained. In order to produce poly (3,4-ethylenedioxythiophene) as the conductive polymer, it is preferable to use 3,4-ethylenedioxythiophene as the monomer.

  Moreover, it is also preferable to contain an oxidizing agent in the polymerization solution. Examples of the oxidizing agent include halides such as iodine and bromine, metal halides such as silicon pentafluoride, proton acids such as sulfuric acid, oxygen compounds such as sulfur trioxide, sulfates such as cerium sulfate, and sodium persulfate. Examples thereof include persulfates, peroxides such as hydrogen peroxide, and iron salts such as iron paratoluate.

  Moreover, it is preferable to contain the dopant for improving the electroconductivity of a conductive polymer in a polymerization liquid. As this dopant, what was illustrated previously in the case of description of the solid electrolyte layer 11 can be used.

  Next, without subjecting the exposed portion 31 to a re-forming process for forming a dielectric layer, in step S13, a predetermined region of the valve metal substrate 16 (a cathode forming portion on which the cathode 15 is to be formed) is formed. Then, a solid electrolyte layer (solid electrolyte layer 11 in FIG. 1) is formed by chemical oxidative polymerization. More specifically, first, the cathode forming portion including the exposed portion 31 in the valve metal substrate 16 is immersed in the polymerization solution, or the polymerization solution is applied to the valve metal substrate 16 by applying the polymerization solution.

  It should be noted that when the polymer solution is attached to the valve metal substrate 16, a region that becomes the anode portion 5 and a region that becomes the cathode portion 6 in order to prevent the polymer solution from penetrating (crawling up) to an undesired region due to capillary action. It is preferable to provide a resist (corresponding to the resist portion 7 in FIG. 1) at the boundary with the (cathode forming portion).

  Subsequently, the monomer contained in the polymerization solution attached to the valve metal substrate 16 is polymerized by, for example, chemical oxidation polymerization, and the solid electrolyte layer 11 is formed on the cathode forming portion of the valve metal substrate 16. This solid electrolyte layer forming step may be performed a plurality of times. Moreover, when the solvent contained in the polymerization liquid volatilizes with the polymerization reaction of the monomer and dissipates to the outside, no particular operation is required to remove this solvent, but it does not volatilize sufficiently with the polymerization reaction. In some cases, it is desirable to remove the solvent as necessary.

  Chemical oxidative polymerization can be performed by adding an oxidizing agent to the polymerization solution as described above, but an oxidizing agent solution in which an oxidizing agent is dissolved in a solvent such as water or alcohol (ethanol, butanol, etc.). May be prepared separately from the polymerization solution, and this oxidant solution may be brought into contact with the valve metal substrate 16 to which the polymerization solution is adhered. Examples of the contact method include a method of immersing the valve metal base 16 in the oxidant solution, a method of applying the oxidant solution to the valve metal base 16, and the like.

  Next, in step S <b> 14, the region where the dielectric layer 10 and the solid electrolyte layer 11 of the valve metal base 16 are formed is immersed in a repair solution to form a dielectric layer on the surface of the valve metal 9. By this repairing process, the dielectric layer 32 is formed on the exposed portion 31 of the valve metal base 16 to reduce the leakage current, and the damaged dielectric layer 10 is repaired when the solid electrolyte layer 11 is formed. can do.

  Here, the repair solution is not particularly limited as long as the dielectric layer can be formed and repaired. For example, a sulfonic acid compound, a carboxylic acid compound, a phosphoric acid compound, sulfuric acid, boric acid, an organic acid, etc. What is contained is used. Examples of the sulfonic acid compound include p-toluenesulfonic acid, sulfoneisophthalic acid and sulfosuccinic acid, methanesulfonic acid, phenolsulfonic acid, sulfosalicylic acid, benzenesulfonic acid, benzenedisulfonic acid, alkylbenzenesulfonic acid and derivatives thereof, and camphorsulfonic acid. Sulfonic acid, diphenolsulfonic acid, naphthalenesulfonic acid and derivatives thereof, anthraquinonesulfonic acid and derivatives thereof, and the like are used. In addition, ammonium salts, sodium salts, potassium salts, and the like of the acid compounds described above are used as the salt compound used as the substance imparting the dopant. That is, in the case of sulfonic acid compounds, ammonium sulfoisophthalate, ammonium sulfosuccinate, ammonium methanesulfonate, ammonium phenolsulfonate, ammonium sulfosalicylate, ammonium benzenesulfonate, ammonium benzenedisulfonate, ammonium alkylbenzenesulfonate as ammonium salts. And derivatives thereof, salts of ammonium camphorsulfonate, ammonium sulfonate acetate, ammonium diphenolsulfonate, and the like. Sodium salts include sodium sulfoisophthalate, sodium sulfosuccinate, sodium methanesulfonate, sodium phenolsulfonate, sodium sulfosalicylate, sodium benzenesulfonate, sodium benzenedisulfonate, sodium alkylbenzenesulfonate and derivatives thereof, camphorsulfonic acid Salts such as sodium, sodium sulfonate acetate, sodium diphenolsulfonate are used. Further, potassium salts include potassium sulfoisophthalate, potassium sulfosuccinate, potassium methanesulfonate, potassium phenolsulfonate, potassium sulfosalicylate, potassium benzenesulfonate, potassium benzenedisulfonate, potassium alkylbenzenesulfonate and derivatives thereof, camphorsulfone. Salts of potassium acid, potassium sulfonate, sulfoaniline, potassium diphenol sulfonate and the like are used.

  Among these, it is preferable to use the sodium salt of aromatic sulfonic acid or the ammonium salt of aromatic sulfonic acid. In addition, the aromatic sulfonic acid is preferably alkyl naphthalene sulfonic acid, and therefore, the repair liquid particularly preferably contains sodium alkyl naphthalene sulfonate or ammonium alkyl naphthalene sulfonate.

  As the repair solution, a solution prepared by dissolving the above materials in a solvent is preferably used. Examples of the solvent include water, a mixture of water and alcohol, and examples of the alcohol include ethanol, butanol, and a mixture thereof.

  Next, in step S15, the carbon paste layer 13 and the silver paste layer 14 are sequentially laminated on the solid electrolyte layer 11 to form a conductor layer (conductor layer 12 in FIG. 2), and the capacitor element 2 is obtained. These layers can be formed by a screen printing method, a dipping method (dip method), a spray coating method, or the like using a paste for forming each layer.

  Further, in step S <b> 16, a desired number of capacitor elements 2 are stacked, and the obtained stacked body is placed on the substrate 20. Then, the cathode portions 6 of the capacitor elements 2 and the cathode portions 6 of the lowermost capacitor elements 2 and the cathode terminals 24 a of the substrate 20 are bonded by the conductive adhesive 17. In addition, laser welding or the like is performed on the anode portion 5 side of the laminated capacitor elements 2 to form a joint portion 30, and the anode portions 5 of the capacitor elements 2 and the lowermost capacitor element 2 and the substrate 20. The anode terminal 22a is joined. In addition, although the oxide film may be formed in the surface of the anode part 5, this oxide film is easily removed by laser welding as mentioned above.

  And after connecting and joining the laminated body composed of a plurality of capacitor elements 2 on the substrate 20 in this way, the laminated body is molded with a resin or the like by a known method such as casting mold, injection, transfer mold, The solid electrolytic capacitor 1 shown in FIG. 1 is obtained.

  Moreover, in the manufacturing method of this invention, after obtaining the solid electrolytic capacitor 1 as mentioned above, it is preferable to perform an aging process as a post-process. The aging treatment can be performed by applying a constant voltage to the anode terminal 22a and the cathode terminal 24a of the solid electrolytic capacitor 1. By performing such an aging treatment, even if a defect occurs in the dielectric layers 10 and 32, it becomes possible to efficiently repair the defect, and it has good capacitor characteristics without causing an increase in leakage current or the like. A solid electrolytic capacitor can be obtained more reliably.

  In such a method of manufacturing the solid electrolytic capacitor 1, as described above, the solid electrolyte layer 11 is formed using a specific polymerization solution, and then a repair process is performed, so that an exposed portion of the valve metal base 16 is exposed. It becomes possible to form the dielectric layer 32 on 31. Therefore, it is possible to manufacture a solid electrolytic capacitor having good capacitor characteristics while realizing an improvement in manufacturing efficiency by omitting the re-forming process. Furthermore, according to the production method of the present invention, the exposed portion 31 is obtained by supplying the polymerization solution without forming a re-chemical conversion treatment to form a solid electrolyte layer and then performing a repairing step. It is possible to reduce the ESR of the solid electrolytic capacitor.

  In addition, the manufacturing method of the solid electrolytic capacitor of this invention is not limited to embodiment mentioned above, In the range which does not change the summary, it can change suitably.

  For example, after the conductor layer 12 is formed, aging in which a constant voltage is applied between the anode part 5 and the cathode part 6 may be performed. Also by this, the damaged part of the dielectric layer 10 can be repaired. In particular, the repair due to aging can be prominent when the solid electrolyte layer 11 contains a proton-donating polymer.

  In addition, the solid electrolytic capacitor obtained by the manufacturing method of the present invention is not necessarily limited to the configuration of the above-described embodiment. That is, the solid electrolytic capacitor is not limited to the one in which the laminated body of the capacitor elements 2 is placed on the substrate 20, and is, for example, a single layer type solid electrolytic capacitor in which only one capacitor element 2 is placed. Also good. The solid electrolytic capacitor 1 is a two-terminal type solid electrolytic capacitor having one anode part 5 and one cathode part 6, but the present invention is a multi-terminal capacitor having a plurality of anode parts and cathode parts. It can also be applied to.

  Furthermore, the anode part 5 may be connected and joined by using, for example, a conductive adhesive other than the laser welding described above. In this case, it is preferable that the oxide film on the surface of the anode portion 5 is removed by etching or the like in order to ensure the electrical connection. Furthermore, in the solid electrolytic capacitor 1, a laminated body of one capacitor element 2 is placed on one substrate 20. In the present invention, a plurality of laminated bodies are provided on one substrate 20. You may be parallel. Further, the solid electrolytic capacitor may include a lead frame, for example, instead of the substrate 20 as described above.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
An electrolytic capacitor was manufactured through the following procedure. That is, first, an aluminum foil with a dielectric layer formed thereon was prepared, in which a dielectric layer made of an aluminum oxide film was formed on the surface of an aluminum foil that had been subjected to a surface expansion treatment as an anode. The aluminum foil having the dielectric layer formed thereon was cut into a work size including a minimum of 3.5 mm × 6.5 mm, and an exposed portion where no dielectric layer was formed was formed on the cut surface. After that, a resist for partitioning the portion (anode portion) to be the anode (anode portion) and the portion to be the cathode (cathode formation portion) on the surface of the aluminum foil on which the dielectric layer has been formed is printed. To obtain a valve metal substrate.

  Subsequently, 0.9 g of 3,4-ethylenedioxythiophene (trade name: BAYTRON (registered trademark) M, manufactured by Bayel) as a monomer constituting the conductive polymer, iron paratoluenesulfonate (trade name: BAYTRON) (Registered trademark) C-B50, manufactured by Bayel) 10.81 g, a polyfluoroethylene solution having a perfluoroalkyl ether side chain containing a sulfonic acid group as a proton-donating polymer (trade name: Nafion (registered trademark) solution SE20192 0.225 g, manufactured by Dupont), 0.108 g of polyvinyl alcohol (trade name: Kuraray Poval PVA403, manufactured by Kuraray) as a water-soluble polymer, and 3.76 g of water were mixed to prepare a polymerization solution. The cathode forming part of the valve metal substrate was dipped in this polymerization solution and then pulled up and subjected to a heat treatment in a furnace at a temperature of 150 ° C. for about 5 minutes to oxidatively polymerize the monomers in the polymerization solution. Thereafter, washing with water and drying treatment were performed. This polymerization treatment from immersion to drying was repeated three times to form a solid electrolyte layer having a thickness of about 0.1 to 10 μm on the cathode forming portion of the valve metal substrate.

  Next, the cathode forming part of the valve metal substrate was immersed in a 0.5% by mass aqueous solution of sodium monoisopropylnaphthalenesulfonate (restoring liquid), and a voltage of 6 V was applied to the aluminum foil constituting the valve metal substrate. Thereby, a dielectric layer was formed on the exposed portion of the valve metal substrate. Thereafter, washing with water and drying were performed.

  Next, a carbon paste layer as a conductor layer is applied to a thickness of 3 μm on the solid electrolyte layer, and a silver paste layer as a conductor layer is further applied to a thickness of 20 μm on the carbon paste layer. did. This formed the cathode which consists of a carbon paste layer and a silver paste layer. Thus, a capacitor element having a structure in which the anode, the dielectric layer, the solid electrolyte layer, and the cathode were laminated in this order was obtained.

  Thereafter, iron leads were respectively connected to the anode and cathode of the capacitor element, and resin molded. After that, a voltage was applied in a high temperature environment to reduce the leakage current so that it could operate at the rated voltage. Thereby, a solid electrolytic capacitor was produced.

(Comparative Example 1)
After producing a valve metal substrate in the same procedure as in Example 1, the cathode forming portion of the valve metal substrate was immersed in an aqueous solution of ammonium adipate as a chemical conversion solution, and a voltage of 6 V was applied to the aluminum foil to perform an anodic oxidation reaction. The anode, dielectric layer, and solid electrolyte layer were the same as in Example 1 except that a re-chemical conversion treatment was performed to form a dielectric layer made of an aluminum oxide film on the exposed portion of the valve metal substrate. And the capacitor | condenser element which has a structure where the cathode was laminated | stacked in this order was obtained.

(Comparative Example 2)
As a polymerization solution, 3,4-ethylenedioxythiophene (trade name: BAYTRON (registered trademark) M, manufactured by Bayel) 0.9 g as a monomer constituting the conductive polymer, iron paratoluenesulfonate (trade name: BAYTRON (registered trademark) C-B50, manufactured by Bayel) 10.81 g and 2.63 g of butanol were used in the same manner as in Example 1 except that an anode, a dielectric layer, a solid electrolyte layer, and A capacitor element having a structure in which the cathode was laminated in this order was obtained.

[Evaluation of capacitor characteristics]
About the solid electrolytic capacitor manufactured by the manufacturing method of Example 1 and Comparative Example 1, using IMPEDANCE / GAIN-PHASE ANALYZER 4194A (trade name, manufactured by HEWLETT PACKARD), electrostatic capacity at 120 Hz, impedance at 100 kHz, The equivalent series resistance (ESR) at 100 kHz and the electrostatic tangent (tan δ) at 120 Hz were measured. Moreover, about the leakage current of the solid electrolytic capacitor manufactured by the manufacturing method of Example 1 and Comparative Example 1, the rated voltage is measured by a known method using a power source and an ammeter (multimeter) that can apply a rated voltage (4 V). The current value 2 minutes after application of was measured as a leakage current. The results are shown in Table 1. The values in Table 1 are average values of values measured at n = 100 for each characteristic.

  As is clear from the results shown in Table 1, according to the method for manufacturing a solid electrolytic capacitor of the present invention (Example 1), excellent capacitor characteristics are achieved while improving the manufacturing efficiency by omitting the re-forming process. It was confirmed that a solid electrolytic capacitor having the following can be obtained. Moreover, the solid electrolytic capacitor obtained by the manufacturing method (Example 1) of the solid electrolytic capacitor of this invention is compared with the solid electrolytic capacitor obtained by the manufacturing method of the solid electrolytic capacitor of the comparative example 1 which implemented the re-forming process. Thus, it was confirmed that ESR can be reduced. In addition, the solid electrolytic capacitor produced by the manufacturing method of Comparative Example 2 was too large in leakage current and could not be used as a solid electrolytic capacitor.

It is a figure which shows typically the cross-sectional structure of the solid electrolytic capacitor obtained by the manufacturing method which concerns on suitable embodiment. 3 is a diagram schematically showing a cross-sectional structure of a main part of a capacitor element 2. FIG. It is a flowchart which shows the manufacturing process of the solid electrolytic capacitor shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Solid electrolytic capacitor, 2 ... Capacitor element, 5 ... Anode part, 6 ... Cathode part, 7 ... Resist part, 9 ... Valve action metal, 10 ... Dielectric layer, 11 ... Electrolyte layer, 12 ... Conductor layer, 13 ... Carbon paste layer, 14 ... silver paste layer, 15 ... cathode, 16 ... valve metal substrate, 17 ... conductive adhesive, 20 ... substrate, 22a, 22b ... anode terminal, 23 ... through hole, 24a, 24b ... cathode terminal, 25 ... through hole, 26, 28 ... resist part, 30 ... joint part.

Claims (4)

A polymerization liquid containing a monomer constituting a conductive polymer, a proton-donating polymer, and a water-soluble polymer on the surface of the valve metal base composed of the valve action metal and including the exposed portion where the dielectric layer is not formed. A solid electrolyte layer forming step of forming a solid electrolyte layer by polymerizing the monomer in the polymerization solution;
A repairing step of forming a dielectric layer on at least the exposed portion;
A conductor layer forming step of forming a conductor layer on the solid electrolyte layer;
A method for producing a solid electrolytic capacitor, comprising: Before the solid electrolyte layer forming step, the valve metal having a dielectric layer formed on the surface is cut, and the exposed portion where the dielectric layer is not formed is formed in a region where the solid electrolyte layer is to be formed. Further comprising a cutting step of obtaining the valve metal substrate,
The method of manufacturing a solid electrolytic capacitor according to claim 1, wherein the solid electrolyte layer forming step is performed after the cutting step without performing a chemical conversion treatment for forming the dielectric layer on the exposed portion.   The method for producing a solid electrolytic capacitor according to claim 1, wherein the proton donating polymer has a perfluoroalkyl ether side chain containing a sulfonic acid group.   The said water-soluble polymer is polyvinyl alcohol, The manufacturing method of the solid electrolytic capacitor as described in any one of Claims 1-3 characterized by the above-mentioned.

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