JP2005191421A - Process for producing electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing a high performance electrolytic capacitor in which operation characteristics are ensured by forming a high quality dielectric layer. <P>SOLUTION: When a dielectric layer 12 (dielectric layer parts 12A-12D ) is formed using an anode 11 on which dielectric layer parts 12A and 12B are partially formed previously, the anode 11 is anodized using pretreatment solution for accelerating anodic oxidation (e.g. adipic acid diammonium aqueous solution), and then anodized using formation solution (e.g. adipic acid diammonium aqueous solution) thus forming dielectric layer parts 12C and 12D. Since anodic oxidation is accelerated on the exposed surfaces PC and PD of the anode 11 at the time of formation treatment, the dielectric layer parts 12C and 12D are formed with high quality to cover the exposed surfaces PC and PD sufficiently. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrolytic capacitor manufacturing method, and more particularly to an electrolytic capacitor manufacturing method including a solid electrolyte layer.

  In recent years, electrolytic capacitors are mounted on various electronic devices as one of electronic components suitable for high-frequency applications. With regard to this electrolytic capacitor, for example, in a situation where the digitization, downsizing and speeding up of electronic devices are accelerating, there is a demand for large capacity and low impedance, as well as operational stability and operation. There is also a demand for ensuring reliability and extending the service life.

  The electrolytic capacitor mainly has a laminated structure in which an anode, a dielectric layer, an electrolyte layer, and a cathode are laminated in this order. The anode is composed of a metal foil or the like of a valve metal, and the dielectric layer is subjected to a treatment (chemical conversion treatment) for forming the dielectric layer on the anode, that is, the surface layer of the anode is anodized. It is comprised by the thin oxide film formed by this. In this electrolytic capacitor, in general, the anode is enlarged (or roughened) for the purpose of realizing a high capacity, and has a fine surface uneven structure, so that it is formed as a surface layer of the anode. Similarly, the dielectric layer has a fine uneven structure. The anode may be constituted by a sintered body of valve action metal fine particles, for example, instead of the metal foil of the valve action metal having an enlarged surface.

  This electrolytic capacitor is mainly divided into two types according to the type of the electrolyte layer. That is, a liquid electrolytic capacitor having an electrolyte layer (electrolytic solution) made of a liquid material and having a conductive mechanism mainly utilizing ion conductivity, and an electrolyte layer made of a solid material such as a conductive polymer ( A solid electrolytic capacitor having a solid electrolyte layer) and having a conductive mechanism mainly utilizing electronic conductivity.

  These two types of electrolytic capacitors have a difference in performance in terms of operating characteristics, for example. That is, in a liquid electrolytic capacitor using a low-conductivity electrolytic solution, an equivalent series resistance (ESR) increases due to the low conductivity of the electrolytic solution, so that an electrical loss occurs during operation. It has the characteristic problem of becoming larger. In contrast, in a solid electrolytic capacitor using a highly conductive solid electrolyte layer, ESR decreases due to the high conductivity of the solid electrolyte layer, unlike a liquid electrolytic capacitor in which ESR increases. The characteristic advantage that the electrical loss is reduced during operation is obtained.

  Also, the two types of electrolytic capacitors have a difference in performance, for example, from the viewpoint of stability of operating characteristics. That is, in a liquid electrolytic capacitor provided with an electrolytic solution, even if the dielectric layer is partially lost due to damage due to external factors, the electrolytic solution (mainly in the electrolytic solution) The anode is reoxidized (anodized) using the moisture of the anode, that is, the defect portion is repaired by newly forming the dielectric layer, so that the anode and the electrolyte are passed through the defect portion of the dielectric layer. The functional advantage that an unnecessary current (leakage current) hardly flows between the two is obtained. The defect repairing function associated with the additional formation of the dielectric layer is generally called an “electrolytic capacitor self-repairing function”. Examples of the “external factor” that induces the loss of the dielectric layer with respect to the liquid electrolytic capacitor include physical damage caused by handling during the manufacturing process of the electrolytic capacitor. In contrast, a solid electrolytic capacitor that does not have an electrolyte solution, unlike a liquid electrolytic capacitor that has a self-healing function, has essentially no self-healing function and is due to external factors. As a result, when the dielectric layer is defective, the defective portion cannot be repaired, so that a leakage current easily flows through the defective portion of the dielectric layer. Examples of the “external factor” that induces the loss of the dielectric layer with respect to the solid electrolytic capacitor include chemical damage during a solid electrolyte layer forming step (for example, a polymerization step of a conductive polymer). When a leakage current occurs, a short circuit is likely to occur due to the leakage current. Although solid electrolytic capacitors do not inherently have a self-healing function, they are affected by the Joule heat generated due to leakage current if the missing portion in the dielectric layer is minimal. As a result, the current path of the leakage current can be interrupted as a result of the solid electrolyte layer partially deconducting. However, if the dielectric layer has a large defect, the above-mentioned decontamination phenomenon of the solid electrolyte layer may occur. Even if it is used, the current path of leakage current cannot be cut off.

  Considering the performance difference between the two types of electrolytic capacitors described above, for example, in order to ensure the operating characteristics of the solid electrolytic capacitor by suppressing the occurrence of leakage current, the dielectric layer is used as an external factor. In order to make it difficult to cause defects, it is necessary to form the dielectric layer with the highest possible quality so as not to include defects that can induce the defects. The “defect” is, for example, a portion where the thickness is partially reduced due to a factor in the formation process of the dielectric layer, or a portion where the physical strength is partially fragile. . In the manufacturing process of the solid electrolytic capacitor, for example, considering the case where the dielectric layer includes an unintentional defect, aging is performed while applying the rated voltage to the completed solid electrolytic capacitor in a high temperature and high humidity environment. By performing the treatment, an additional dielectric layer is formed on the defect, that is, an operation of temporarily repairing the defect of the dielectric layer is also performed. However, as described above, a solid electrolytic capacitor that does not inherently have a self-healing function may not be able to block the current path of the leakage current depending on the state of loss of the dielectric layer. Since there is a possibility that defects in the dielectric layer cannot be sufficiently repaired, a manufacturing technology that can fundamentally form a high-quality dielectric layer to prevent the occurrence of a short circuit due to leakage current Is desired.

As a technique for forming the dielectric layer with high quality, a specific technique has already been proposed. Specifically, for example, a technique is known in which a dielectric layer is formed by subjecting a sintered body of valve action metal to a two-stage chemical conversion treatment. In this technique, after performing a chemical conversion treatment at a relatively high current density, a dielectric layer is formed by performing a chemical conversion treatment at a relatively low current density, or a chemical conversion having a relatively high electrical conductivity. The dielectric layer is formed by performing chemical conversion treatment using a chemical conversion solution having relatively low electrical conductivity after chemical conversion treatment using the solution (see, for example, Patent Document 1). .
Japanese Patent No. 3362600

  By the way, in the manufacturing process of the solid electrolytic capacitor, for example, after obtaining an untreated valve action metal foil that has not been previously subjected to chemical conversion treatment as an anode, that is, no dielectric layer is formed in advance, the valve action is obtained. In addition to the procedure for forming a dielectric layer by subjecting a metal foil to a chemical conversion treatment, a chemical conversion treatment has been performed in advance, that is, a processed valve action metal foil having a dielectric layer partially formed in advance is obtained. After that, a procedure for additionally forming a dielectric layer by performing chemical conversion treatment (so-called re-chemical conversion treatment) on the valve action metal foil is also used. This treated valve metal foil is formed by, for example, forming a dielectric layer so as to cover the periphery of the valve metal foil, and then cutting the valve metal foil together with the dielectric layer to a predetermined size. In other words, the valve-acting metal foil is partially exposed at a portion (cut surface) where the dielectric layer is not formed. When using this treated valve metal foil, as described above, a solid electrolyte layer is applied to the valve metal foil due to structural factors that partially expose the valve metal foil. If formed directly, the solid electrolyte layer is short-circuited by coming into contact with the exposed surface of the valve action metal foil. Therefore, in order to prevent the short-circuit, the dielectric layer is formed by subjecting the valve action metal foil to re-chemical conversion. It is necessary to form additionally.

  However, when a solid electrolytic capacitor is manufactured using a treated valve metal foil, unlike the case where a solid electrolytic capacitor is manufactured using an untreated valve metal foil, a re-forming treatment is performed. When the dielectric layer is formed with high quality so as to cover the valve action metal foil, the dielectric layer partially formed on the valve action metal foil in advance has a defect (caused by chemical damage accompanying the re-forming process). An additional dielectric layer must be formed to sufficiently cover the exposed surface of the valve metal foil without causing defects. In this regard, in the conventional manufacturing technique using the above-described two-stage chemical conversion treatment in which the current density and electric conductivity are changed, the two-stage chemical conversion is applied when the manufacturing technique is applied to the treated valve metal foil. Since no consideration is given to how the process affects the quality of the dielectric layer, it is unclear whether the dielectric layer can be formed with high quality using its conventional manufacturing techniques. Therefore, in order to manufacture a high-performance solid electrolytic capacitor in which operating characteristics are ensured by using a processed valve action metal foil, in order to suppress the occurrence of leakage current, a dielectric material is passed through a re-forming process. A manufacturing technique capable of forming a layer with high quality is required. In particular, because of the rapid miniaturization and increase in capacity of solid electrolytic capacitors, the dielectric layer has become extremely thin, and the extremely thin dielectric layer is extremely susceptible to damage Technical background In view of the above, establishment of the above manufacturing technology is urgent.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrolytic capacitor capable of producing a high-performance electrolytic capacitor with ensured operating characteristics by forming a dielectric layer with high quality. It is in providing the manufacturing method of.

  An electrolytic capacitor manufacturing method according to a first aspect of the present invention includes an electrode layer made of a valve metal, a dielectric layer formed by anodizing the electrode layer, and a solid electrolyte layer. This is a method for producing an electrolytic capacitor having a laminated structure laminated in this order. The electrode layer is pretreated using a pretreatment solution for promoting the anodic oxidation reaction of the electrode layer, and then the chemical conversion solution is added. And a step of forming a dielectric layer by anodizing the electrode layer.

  In the method for manufacturing an electrolytic capacitor according to the first aspect of the present invention, after the electrode layer is pretreated using the pretreatment solution for promoting the anodic oxidation treatment of the electrode layer, the chemical conversion solution is used. The dielectric layer is formed by anodizing the pretreated electrode. In this case, for example, an electrode layer in which a dielectric layer (first dielectric layer portion) is partially formed in advance is used, and the electrode layer is pretreated using a pretreatment solution. The second dielectric layer portion is formed by anodizing the electrode layer using a chemical conversion solution, so that the dielectric layer including these first and second dielectric layer portions is If it is formed so as to cover, the anodic oxidation reaction of the electrode layer is promoted by this pretreatment. Therefore, the exposed portion of the electrode layer (the portion where the first dielectric layer portion is not formed in advance) The second dielectric layer portion is formed with high quality so as to sufficiently cover the surface.

  An electrolytic capacitor manufacturing method according to a second aspect of the present invention includes an electrode layer made of a valve metal, a dielectric layer formed by anodizing the electrode layer, and a solid electrolyte layer. This is a method of manufacturing an electrolytic capacitor having a laminated structure laminated in this order. After pre-treating the electrode layer using a pre-treatment solution for repairing the dielectric layer, a chemical conversion solution is used. The method includes a step of forming a dielectric layer by anodizing the electrode layer.

  In the method for manufacturing an electrolytic capacitor according to the second aspect of the present invention, after the electrode layer is pretreated using the pretreatment solution for repairing the dielectric layer, the chemical treatment solution is used for the pretreatment. The dielectric layer is formed by anodizing the used electrode. In this case, for example, an electrode layer in which a dielectric layer (first dielectric layer portion) is partially formed in advance is used, and the electrode layer is pretreated using a pretreatment solution. The second dielectric layer portion is formed by anodizing the electrode layer using a chemical conversion solution, so that the dielectric layer including these first and second dielectric layer portions is If it is formed so as to cover, the first dielectric layer portion is repaired by this pretreatment, so that the quality of the first dielectric layer portion is improved so as not to include defects.

  In the electrolytic capacitor manufacturing method according to the first aspect of the present invention, in the second step, an electrolyte solution may be used as the pretreatment solution, and the electrode layer may be immersed in the electrolyte solution. It is preferable to use a chemical conversion solution as the electrolyte solution. In this case, it is particularly preferable to make the concentration of the pretreatment solution higher than the concentration of the chemical conversion solution.

  In the method for producing an electrolytic capacitor according to the second aspect of the present invention, in the second step, water may be used as a pretreatment solution, and the electrode layer may be immersed in the water. In this case, it is preferable to use boiling water as water.

  In the electrolytic capacitor manufacturing method according to the first or second aspect of the present invention, in the first step, the first dielectric layer portion is formed as the electrode layer so as to cover the periphery of the electrode layer. After that, the electrode layer cut along with the first dielectric layer portion may be prepared.

  According to the method for manufacturing an electrolytic capacitor in accordance with the first aspect of the present invention, the dielectric including the second dielectric layer portion is based on a manufacturing feature in which the second dielectric layer portion is formed with high quality. Since the generation of the leakage current is suppressed by forming the layer with high quality, it is possible to manufacture a high-performance electrolytic capacitor with ensured operating characteristics.

  In addition, according to the method for manufacturing an electrolytic capacitor according to the second aspect of the present invention, the dielectric including the first dielectric layer portion is based on a manufacturing feature that improves the quality of the first dielectric layer portion. Since the body layer is formed with high quality, the occurrence of leakage current is suppressed, so that a high-performance electrolytic capacitor with ensured operating characteristics can be manufactured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, with reference to FIG. 1 and FIG. 2, the structure of the electrolytic capacitor manufactured using the manufacturing method of the electrolytic capacitor based on the 1st Embodiment of this invention is demonstrated easily. 1 and 2 show the configuration of the main part (capacitor element 10) of the electrolytic capacitor, FIG. 1 shows the external configuration, and FIG. 2 is an enlarged cross-sectional configuration along the line II-II shown in FIG. As shown.

  In the electrolytic capacitor manufactured in this embodiment, an anode lead and a cathode lead (both not shown) are connected to capacitor element 10 shown in FIGS. 1 and 2, and both of these anode lead and cathode lead are The capacitor element 10 has a structure in which it is covered with a mold resin (not shown) so as to be partially exposed. The capacitor element 10 generates an electrical reaction as a main part of the electrolytic capacitor. For example, as shown in FIGS. 1 and 2, the anode 11 and the periphery (one end) of the anode 11 are partially provided. A dielectric layer 12 provided to cover the dielectric layer 12, a solid electrolyte layer 13 provided to cover the periphery of the dielectric layer 12, and a cathode 14 provided to cover the periphery of the solid electrolyte layer 13. In other words, the anode 11, the dielectric layer 12, the solid electrolyte layer 13 and the cathode 14 are laminated in this order.

  The anode 11 functions as an electrode layer for causing an electrical reaction. The anode 11 is made of, for example, aluminum (Al), tantalum (Ta), niobium (Nb), titanium (Ti), hafnium (Hf), zirconium (Zr), zinc (Zn), tungsten (W), bismuth (Bi). ) Or antimony (Sb). Specifically, the anode 11 is made of, for example, a metal foil such as aluminum having an uneven surface (or roughened) surface uneven structure, and the thickness thereof is about 1 μm to 500 μm. The surface uneven structure of the anode 11 will be described later (see FIG. 3). Note that the anode 11 may be formed of a sintered body of metal particles such as tantalum instead of the above-described metal foil such as aluminum.

  The dielectric layer 12 is formed, for example, by subjecting the anode 11 to a treatment (chemical conversion treatment) for forming the dielectric layer 12, that is, by anodizing the surface layer of the anode 11 made of a valve metal. Oxide film. For example, when the anode 11 is made of aluminum, the dielectric layer 12 is made of aluminum oxide, which is an oxide of the aluminum, and has a thickness of about 5 nm to 1 μm. In particular, the dielectric layer 12 includes, for example, dielectric layer portions 12A and 12B provided so as to face each other across the anode 11, as shown in FIG. 2, and together with these dielectric layer portions 12A and 12B. The dielectric layer portions 12C and 12D are provided so as to cover the anode 11.

  The solid electrolyte layer 13 includes a conductive polymer (conjugated polymer) generated by polymerizing a monomer through, for example, a chemical oxidative polymerization reaction or an electrolytic oxidative polymerization reaction. The thickness is about 20 nm to 1 μm. Note that the thickness of the solid electrolyte layer 13 may be, for example, about 20 nm to 10 μm in a high withstand voltage type electrolytic capacitor. This conductive polymer is composed of, for example, at least one member selected from the group including polyaniline, polypyrrole, polythiophene, and derivatives thereof. Specifically, polyethylene diol, which is a derivative of polyaniline, polypyrrole, or polythiophene. It is composed of oxythiophene. The capacitor element 10 provided with the solid electrolyte layer 13 is a so-called solid electrolytic capacitor element. In particular, the solid electrolyte layer 13 may include, for example, a dopant for increasing the conductivity of the conductive polymer as needed, that is, a conductive polymer doped with the dopant. Examples of the dopant include at least one member selected from the group comprising alkylbenzene sulfonic acid and its salt, alkyl naphthalene sulfonic acid and its salt, and phosphoric acid. Examples include sodium naphthalene sulfonate.

  The cathode 14 has the same function as the anode 11. The cathode 14 is made of, for example, a conductive material such as carbon (graphite) or metal, and specifically has a two-layer structure in which a carbon layer 14A and a silver (Ag) layer 14B are stacked. Yes. The cathode 14 does not necessarily have a two-layer structure, for example, and may have a single-layer structure or a laminated structure of three or more layers.

  For reference, each of the anode lead and the cathode lead is made of, for example, a metal such as iron (Fe) or copper (Cu), or a plated metal obtained by plating these metals. The capacitor element 10 is connected to the anode 11 and the cathode 14 respectively. Examples of the above “plating treatment” include tin (Sn) plating treatment and tin lead (SnPb) plating treatment. The mold resin is made of, for example, an insulating resin. Specifically, the mold resin is made of a phenol resin, a polyimide resin, an epoxy resin, a polyester resin, or the like excellent in adhesion and solvent resistance.

  Next, a detailed configuration of the capacitor element 10 will be described with reference to FIG. FIG. 3 is a partially enlarged cross-sectional view of the capacitor element 10 shown in FIG.

  In the capacitor element 10, for example, as shown in FIG. 3, the dielectric layer 12, the solid electrolyte layer 13, and the cathode 14 (carbon layer 14A, silver layer 14B) are laminated in this order so as to cover the anode 11. . In this capacitor element 10, as described above, in order to realize a high capacity by increasing the surface area of the anode 11, the anode 11 is enlarged (or roughened). It has a fine surface uneven structure. Accordingly, the dielectric layer 12 formed so as to cover the anode 11 also has a fine concavo-convex structure. In particular, the dielectric layer 12 forms a plurality of pores 12H as recesses in the concavo-convex structure, and the solid electrolyte layer 13 partially enters the pores 12H of the dielectric layer 12.

  Next, with reference to FIGS. 1-7, the manufacturing method of the electrolytic capacitor provided with the capacitor | condenser element 10 shown in FIGS. 1-3 is demonstrated as a manufacturing method of the electrolytic capacitor based on this Embodiment. FIG. 4 is a diagram for explaining the flow of the electrolytic capacitor manufacturing process, and FIG. 5 is a series of solutions (pretreatment solution, chemical conversion solution, monomer solution, oxidant solution) used in the electrolytic capacitor manufacturing process. ) For explaining the composition. 6 and 7 show cross-sectional configurations of the anode 11 before and after the chemical conversion treatment, FIG. 6 shows a state before the chemical conversion treatment, and FIG. 7 shows a state after the chemical conversion treatment. The cross-sectional configurations shown in FIGS. 6 and 7 both correspond to FIG.

  When manufacturing an electrolytic capacitor, first, as an anode 11 (see FIG. 3) constituted by a metal foil (for example, aluminum surface-enhanced foil) that has been subjected to a surface expansion treatment of a valve action metal, for example, shown in FIG. As described above, the dielectric layer portions 12A and 12B (first dielectric layer portion) constituting a part of the dielectric layer 12 are partially formed in advance, that is, by the dielectric layer portions 12A and 12B in advance. A partially covered anode 11 is prepared (step S101). In the anode 11 shown in FIG. 6, for example, each of four surfaces constituting a rectangular cross section, that is, one of the surfaces PA, PB, PC, and PD facing each other, is set on one surface PA, PB. Dielectric layer portions 12A and 12B are formed in advance, and the other set of surfaces PC and PD are both exposed. As the anode 11, for example, the wide-width anode 11 is previously subjected to chemical conversion treatment, and the dielectric layer portions 12 </ b> A and 12 </ b> B are formed so as to cover the periphery of the anode 11. The anode 11 is cut together with the dielectric layer portions 12A and 12B so as to have a predetermined dimension (for example, a strip shape), so that the surfaces PC and PD are formed as cut surfaces after cutting. In addition, as the anode 11, for example, a material that is cut using a method such as a cutter, a dicing saw, a slitter, a shear shear, or a laser may be used instead of the punching machine. For example, as shown in FIG. 3, the dielectric layer portions 12A and 12B have a concavo-convex structure corresponding to the surface concavo-convex structure of the anode 11, and a plurality of pores 12H are formed as concave portions in the concavo-convex structure. In addition, when the constituent material of the anode 11 is an aluminum surface-enlarging foil, the anode 11 is made of aluminum oxide.

  After preparing the anode 11 in which the dielectric layer portions 12A and 12B are partially formed in advance, the dielectric layer 12 including the dielectric layer portions 12A and 12B is formed so as to cover the periphery of the anode 11 (step) S102). When this dielectric layer 12 is formed, a pretreatment solution for accelerating the anodic oxidation reaction of the anode 11 is used, the anode 11 is pretreated, and then a chemical conversion solution is used to form the anode 11. Is anodized (so-called re-chemical conversion).

  The procedure for forming the dielectric layer 12 is as follows. That is, first, for example, as shown in FIG. 5, an electrolyte solution in which an electrolyte is dissolved in a solvent is prepared as a pretreatment solution (step S1021). As this pretreatment solution (electrolyte solution), for example, a chemical conversion solution used in a post-process is used, that is, a solution having the same solution composition as the chemical conversion solution. The expression “having the same solution composition” means that the type of electrolyte and solvent constituting the pretreatment solution is the same as the type of electrolyte and solvent constituting the chemical conversion solution. It does not mean that the concentration is the same as that of the chemical conversion solution. In particular, when preparing the pretreatment solution, for example, the concentration C1 of the pretreatment solution is set to be higher than the concentration C2 of the chemical conversion solution (C1> C2).

  Subsequently, the anode 11 is pretreated using the pretreatment solution (step S1022). Specifically, the pretreatment solution is adhered to the exposed surfaces PC and PD of the anode 11 by immersing the anode 11 in the pretreatment solution. By this pretreatment, when the anode 11 is anodized in the chemical conversion treatment step described later, the anodization reaction is promoted on the exposed surfaces PC and PD of the anode 11.

  Subsequently, the pretreated anode 11 is pulled up from the pretreatment solution, and the anode 11 is dried as necessary. For example, as shown in FIG. 5, a chemical conversion solution in which an electrolyte is dissolved in a solvent is prepared. (Step S1023). When preparing this chemical conversion solution, for example, borate, phosphate, or adipate is used as an electrolyte, specifically, diammonium adipate is used, and distilled water is used as a solvent. . In particular, when preparing the chemical conversion solution, for example, the concentration C2 of the chemical conversion solution is made lower than the concentration C1 of the pretreatment solution (C2 <C1). Before confirmation, preparation of the chemical conversion solution does not necessarily have to be performed after pretreatment, and the preparation time of the chemical conversion solution can be freely changed. Specifically, for example, when preparing the pretreatment solution, the chemical conversion solution may be prepared together.

  Subsequently, a chemical conversion treatment is performed on the anode 11 using the chemical conversion solution (step S1024). Specifically, an anodic oxidation reaction is allowed to proceed at the anode 11 by applying a voltage (= about 1 V to 40 V) while the anode 11 is immersed in the chemical conversion solution. The applied voltage value at the time of the chemical conversion treatment is not necessarily limited to the voltage value described above, and can be freely set according to the withstand voltage of the anode 11, the formation thickness of the dielectric layer 12, and the like. This chemical conversion treatment forms dielectric layer portions 12C and 12D (second dielectric layer portions) constituting other parts of the dielectric layer 12 so as to cover the exposed surfaces PC and PD of the anode 11. The dielectric layer 12 including the dielectric layer portions 12A to 12D is formed so as to cover the periphery of the anode 11. In particular, in the chemical conversion treatment, the anodic oxidation reaction is promoted on the exposed surfaces PC and PD of the anode 11 based on the fact that the anode 11 has been pretreated in the pretreatment step. Dielectric layer portions 12C and 12D are formed so as to cover.

  Subsequently, after forming the dielectric layer 12, for example, as shown in FIG. 5, a monomer solution in which a monomer and a dopant are dissolved in a solvent is prepared, and the monomer solution has been subjected to chemical conversion treatment. The monomer solution is adhered to the surface of the dielectric layer 12 by immersing the anode 11. When preparing this monomer solution, for example, at least one of aniline, pyrrole, thiophene and derivatives thereof is used as a monomer, specifically, 3,4- In addition to using ethylenedioxythiophene, at least one member selected from the group including alkylbenzene sulfonic acid and its salt, alkyl naphthalene sulfonic acid and its salt, and phosphoric acid as a dopant, specifically, alkyl naphthalene sulfonic acid The salt sodium alkylnaphthalene sulfonate is used. In addition, as a solvent, ethanol etc. are used, for example.

  Subsequently, after the anode 11 is pulled up from the monomer solution and dried, for example, as shown in FIG. 5, an oxidant solution in which an oxidant is dissolved in a solvent is prepared. The anode 11 that has been immersed in the body solution is immersed. When preparing this oxidant solution, for example, metal halides, protonic acids, sulfur trioxide, oxygen compounds (for example, nitrogen dioxide), sulfates (for example, cerium sulfate), persulfates (for example, persulfate) as oxidants. Sodium), nitrates (eg cerium nitrate) or peroxides (eg potassium permanganate). In addition, as a solvent, distilled water etc. are used, for example. Since the monomer in the monomer solution attached to the dielectric layer 12 is polymerized by this immersion treatment, the solid electrolyte layer 13 is formed so as to cover the periphery of the dielectric layer 12 (dielectric layer portions 12A to 12D). It is formed (step S103). Specifically, for example, a monomer is chemically oxidatively polymerized using an oxidizing agent to produce a conductive polymer, so that the conductive polymer contains a dopant together with the conductive polymer, that is, the conductive material doped with the dopant. The solid electrolyte 13 is formed so as to include a conductive polymer. As the conductive polymer, for example, at least one of polyaniline, polypyrrole, polythiophene, and derivatives thereof is generated. Specifically, when 3,4-ethylenedioxythiophene is used as a monomer Produces polyethylenedioxythiophene.

  Subsequently, the solid electrolyte layer 13 is washed with water, for example, an unreacted monomer contained in the conductive polymer, an excess dopant not doped in the conductive polymer, and a used oxidizing agent. Are washed away (step S104). When forming the solid electrolyte layer 13, for example, the combination of the “solid electrolyte layer 13 forming step (step S 103)” and the “solid electrolyte layer 13 rinsing step (step S 104)” described above is performed once. Not limited to this, it may be repeated over a plurality of times. By performing a combination of these steps a plurality of times, the formation thickness of the solid electrolyte layer 13 can be adjusted to a desired thickness.

  Subsequently, the cathode 14 is formed so as to cover the periphery of the solid electrolyte layer 13 (step S105). When forming the cathode 14, for example, a carbon paste is applied around the solid electrolyte layer 13 and dried to form a carbon layer 14A having a thickness of about 10 μm, and then on the carbon layer 14A. The silver layer 14B is formed to have a thickness of about 30 μm by further applying a silver paste and drying, that is, the cathode so as to have a two-layer structure in which the carbon layer 14A and the silver layer 14B are laminated in this order. 14 is formed. Thereby, the capacitor element 10 having a laminated structure in which the anode 11, the dielectric layer 12, the solid electrolyte layer 13, and the cathode 14 are laminated in this order is completed (see FIGS. 1 to 3).

  After the capacitor element 10 is formed, an electrolytic capacitor is assembled using the capacitor element 10. That is, for example, the anode lead of the capacitor element 10 is connected to the anode 11 and the cathode lead is connected to the cathode 14 using a joining technique such as resistance welding, ultrasonic welding, or caulking (step S106). The capacitor element 10 is covered with a mold resin so that both the anode lead and the cathode lead are partially exposed (step S107). Thereby, the anode lead and the cathode lead are connected to the capacitor element 10, and the electrolytic capacitor having a structure in which the capacitor element 10 is covered with the mold resin so as to partially expose the anode lead and the cathode lead is completed. Note that after the electrolytic capacitor is completed, the electrolytic capacitor may be subjected to an aging treatment as necessary. As this aging treatment, for example, a rated voltage is applied to the electrolytic capacitor in a high temperature and high humidity environment.

  In the method for manufacturing an electrolytic capacitor according to the present embodiment, anode 11 in which dielectric layer portions 12A and 12B are partially formed in advance is used, and dielectric layer 12 (dielectric layer portions 12A to 12A to 12A) is formed on anode 11. 12D), the anode 11 is pretreated using a pretreatment solution for promoting the anodic oxidation reaction, and then the anode 11 is anodized using a chemical conversion solution. Since the portions 12C and 12D are formed, as described above, based on the fact that the pretreatment solution adheres to the exposed surfaces PC and PD of the anode 11 by the pretreatment, anodization is performed on the exposed surfaces PC and PD during the chemical conversion treatment. The reaction is promoted. In this case, the dielectric layer portions 12C and 12D are formed so as to sufficiently cover the exposed surfaces PC and PD of the anode 11, that is, the thickness of the portion covering the exposed surfaces PC and PD becomes sufficiently large and the pinhole. The dielectric layer portions 12C and 12D are formed with high quality so as not to include defects such as. As a result, based on the improvement in quality of the dielectric layer portions 12C and 12D, the dielectric layer 12 including the dielectric layer portions 12C and 12D is formed with high quality. Therefore, in the present embodiment, since the generation of leakage current is suppressed based on the improvement of the quality of the dielectric layer 12, a high-performance electrolytic capacitor with ensured operating characteristics can be manufactured. Thereby, when manufacturing an electrolytic capacitor, the manufacturing yield of the electrolytic capacitor can be improved.

  In addition to the above, in this embodiment, since the concentration C1 of the pretreatment solution is higher than the concentration C2 of the chemical conversion solution (C1> C2), the anode based on the pretreatment using the pretreatment solution The promoting action of the oxidation reaction is ensured to such an extent that the dielectric layer portions 12C and 12D can be formed so as to sufficiently cover the exposed surfaces PC and PD of the anode 11. Therefore, the dielectric layer portions 12C and 12D can be stably formed with high quality.

  In the present embodiment, since the chemical conversion solution is used as the pretreatment solution, the anode 11 is substantially twice in the process in which the anode 11 is processed through both the pretreatment process and the chemical conversion process. Will come into contact with the chemical conversion solution. In this case, considering that the dielectric layer portions 12C and 12D are formed using the chemical conversion solution, the anode 11 can be sufficiently brought into contact with the pretreatment solution (= the chemical conversion solution) in the pretreatment step. For example, since it is not necessary to sufficiently contact the anode 11 with the chemical conversion solution in the chemical conversion treatment, the concentration C2 of the chemical conversion solution may be lower than in the case where the chemical conversion solution is not used as the pretreatment solution. Therefore, the concentration C2 of the chemical conversion solution can be reduced. In particular, when the concentration C2 of the chemical conversion solution is likely to change due to evaporation by reducing the concentration C2 of the chemical conversion solution, the progress of the chemical conversion action (the progress of the anodic oxidation reaction) based on the change in the concentration C2. ) Can be substantially suppressed.

  In the present embodiment, the anode 11 is immersed in the pretreatment solution in order to adhere the pretreatment solution to the anode 11 in the pretreatment step using the pretreatment solution. As long as it is possible to attach the pretreatment solution to the anode 11, the deposition method can be freely changed. Specifically, for example, instead of the method of immersing the anode 11 in the pretreatment solution, the pretreatment solution may be dropped on the anode 11 or the pretreatment solution may be applied to the anode 11. In these cases, the same effects as those of the above embodiment can be obtained.

  Further, in the present embodiment, as shown in FIG. 5, the dielectric layer portions 12C and 12D are formed by subjecting the anode 11 to a chemical conversion treatment only once using one type of chemical conversion solution. However, the present invention is not necessarily limited to this. As long as the dielectric layer portions 12C and 12D can be formed with high quality, a plurality of chemical conversion solutions having different reaction rates are sequentially used to form the anode 11. The dielectric layer portions 12C and 12D may be formed by performing a chemical conversion treatment a plurality of times. Specifically, after performing a chemical conversion treatment (pre-chemical conversion treatment) on the anode 11 using a chemical conversion solution (pre-chemical conversion solution) having a relatively fast reaction rate, The anode 11 may be subjected to a chemical conversion treatment (post chemical conversion treatment) using a post chemical conversion solution. As an example, as shown in FIG. 8, after the pre-chemical conversion treatment is performed on the anode 11 using a pre-chemical solution having a relatively high concentration C21 (C21> C22), a relatively low concentration C22 is obtained. If a post-forming treatment is performed on the anode 11 using a post-forming solution having (C22 <C21), the dielectric layers 12C and 12D are formed through these pre-forming and post-forming treatments. . The type of electrolyte and solvent constituting the pretreatment solution and the type of electrolyte and solvent constituting the post-forming solution may be the same or different from each other. In addition, when performing the chemical conversion treatment (pre-chemical conversion treatment, post-chemical conversion treatment) on the anode 11 using the pre-chemical conversion solution (concentration C21) and the post-chemical conversion solution (concentration C22) shown in FIG. The temperature of the solution may be made higher than the temperature of the post-chemical conversion solution, or the processing time of the pre-chemical conversion treatment may be made shorter than the processing time of the post-chemical conversion treatment. Even in this case, the same effect as the above embodiment can be obtained.

[Second Embodiment]
Next, a second embodiment relating to the present invention will be described.

  Unlike the first embodiment in which the anode 11 is pretreated using the pretreatment solution for promoting the anodic oxidation reaction, the electrolytic capacitor manufacturing method according to the present embodiment is a dielectric layer. Except that the anode 11 is pretreated using a pretreatment solution for repairing the portions 12A and 12B, the same procedure as that for the electrolytic capacitor manufacturing method described in the first embodiment (FIG. 4, (See FIGS. 6 and 7).

  FIG. 9 is a view for explaining the composition of a series of solutions (pretreatment solution, chemical conversion solution, monomer solution, oxidant solution) used in the manufacturing process of the electrolytic capacitor. When the electrolytic capacitor shown in FIGS. 1 to 3 is manufactured using the electrolytic capacitor manufacturing method according to the present embodiment, the manufacturing process described with reference to FIG. 4 in the first embodiment. 6, after preparing the processed anode 11 shown in FIG. 6 (step S 101), when forming the dielectric layer 12 on the anode 11 (step S 102), as described above, the anode 11 is partially applied in advance. After the anode 11 is pretreated using a pretreatment solution for repairing the dielectric layer portions 12A and 12B formed on the anode 11, the anode 11 is anodized using a chemical conversion solution (so-called re-treatment). Conversion).

  That is, when forming the dielectric layer 12, first, for example, as shown in FIG. 9, water is prepared as a pretreatment solution (step S1021). As this pretreatment solution (water), for example, distilled water is used. In particular, as the pretreatment solution (water), for example, boiling water (boiling distilled water) is preferably used. The boiling distilled water is, for example, distilled water having an actually measured temperature of about 95 ° C to 100 ° C. Subsequently, the anode 11 is pretreated using the pretreatment solution, that is, the anode 11 is immersed in the pretreatment solution, thereby attaching water to the surfaces of the dielectric layer portions 12A and 12B. (Step S1022). By this pretreatment, the coating layers PA and PB of the anode 11 are anodized during the chemical conversion treatment, so that the dielectric layer portions 12A and 12B are restored. In addition, the process after the process (step S1023) after preparing a chemical conversion solution after pre-processing to the anode 11 using a pre-process solution is the same as the manufacturing process of the electrolytic capacitor of the said 1st Embodiment. Since there is, explanation is omitted. Also in the manufacturing process of this electrolytic capacitor, the dielectric layer portions 12C and 12D are respectively formed so as to cover the exposed surfaces PC and PD of the anode 11 by subjecting the anode 11 to chemical conversion using a chemical conversion solution. Therefore, as shown in FIG. 7, dielectric layer 12 including dielectric layer portions 12 </ b> A to 12 </ b> D is formed so as to cover anode 11.

  In the method for manufacturing an electrolytic capacitor according to the present embodiment, anode 11 in which dielectric layer portions 12A and 12B are partially formed in advance is used, and dielectric layer 12 (dielectric layer portions 12A to 12A to 12A) is formed on anode 11. 12D), the anode 11 is pretreated using a pretreatment solution for repairing the dielectric layer portions 12A and 12B, and then the anode 11 is anodized using a chemical conversion solution. Since the dielectric layer portions 12C and 12D are formed by the above, the dielectric layer is formed during the chemical conversion treatment based on the fact that the pretreatment solution adheres to the surfaces of the dielectric layer portions 12A and 12B by the pretreatment as described above. Portions 12A and 12B are repaired. Specifically, regarding the treated anode 11 used for manufacturing the electrolytic capacitor, the dielectric layer portions 12A and 12B partially formed in advance on the anode 11 include defects unintentionally. Even if water (that is, hydroxyl groups) adheres to the surfaces of the dielectric layer portions 12A and 12B during the pretreatment, the defects in the dielectric layer portions 12A and 12B are electrically protected during the chemical conversion treatment based on the presence of the water. Therefore, the concentration of electrical action (that is, electric field) on the defects of the dielectric layer portions 12A and 12B is suppressed. As a result, the dielectric layer portions 12C and 12D are embedded and repaired without damaging the dielectric layer portions 12A and 12B due to the presence of defects, while the dielectric layer portions 12A and 12B are buried and repaired. Therefore, the quality of the dielectric layer portions 12A and 12B is improved. As a result, the dielectric layer 12 is formed with high quality based on the improvement of the quality of the dielectric layer portions 12A and 12B. Therefore, in the present embodiment, since the generation of leakage current is suppressed based on the improvement of the quality of the dielectric layer 12, a high-performance electrolytic capacitor with ensured operating characteristics can be manufactured.

  In addition to the above, in this embodiment, if boiling water is used as the pretreatment solution, the pretreatment solution adheres to the dielectric layer portions 12A and 12B using the thermal action of the boiling water. Therefore, pretreatment can be performed in a short time.

  In addition, the structure of the electrolytic capacitor manufactured using the manufacturing process other than the above regarding the manufacturing method of the electrolytic capacitor which concerns on this Embodiment, a modified example, and the manufacturing method of an electrolytic capacitor is the same as that of the said 1st Embodiment. It is.

  Next, specific examples relating to the present invention will be described.

  An electrolytic capacitor was manufactured using the method for manufacturing an electrolytic capacitor described in the above embodiment. That is, first, after preparing a wide pre-treated aluminum foil, that is, an aluminum foil (aluminum surface-enhanced foil) that has been previously enlarged and partially formed with dielectric layer portions 12A and 12B. By punching the aluminum foil so as to have a predetermined dimension (15 mm × 30 mm) using a punching machine, the anode 11 (the thickness of the anode 11 = 20 μm, the thickness of the dielectric layer portions 12A, 12B = 40 μm; (See FIG. 6). When punching out the pretreated aluminum foil using a punching machine, the depth of cut of the cutting blade was adjusted using a spacer.

  Subsequently, in order to define a region functioning as an electrolytic capacitor (capacitor region), the anode 11 was sealed so that a region having a predetermined dimensional angle was selectively exposed. Subsequently, after preparing a pretreatment solution, the anode 11 was pretreated by immersing the anode 11 in the pretreatment solution. Subsequently, after the chemical conversion solution was prepared, the chemical conversion treatment was performed by applying a voltage while immersing the pretreated anode 11 in the chemical conversion solution, so that the anodic oxidation reaction proceeded at the anode 11. In performing this chemical conversion treatment, an aqueous solution of diammonium adipate was used as the chemical conversion solution, and the applied voltage was set to 23V. By this chemical conversion treatment, the dielectric layer portions 12C and 12D are formed so as to cover the exposed surfaces PC and PD of the anode 11, that is, the dielectric layer 12 (dielectric layer portions 12A to 12D is formed so as to cover the periphery of the anode 11. ) Was formed.

  Subsequently, a monomer solution in which 0.56 g of 3.4-ethylenedioxythiophene as a monomer and 3.2 g of sodium alkylnaphthalene sulfonate as a dopant were dissolved in 30 mL of ethanol as a solvent, The anode 11 after chemical conversion treatment is immersed in the monomer solution for 30 seconds to attach the monomer solution to the surface of the dielectric layer 12, and then the anode 11 is pulled up for 1 minute at room temperature. Dried over. Subsequently, after preparing an oxidant solution in which 1.2 g of cerium sulfate as an oxidant was dissolved in 20 mL of distilled water as a solvent, the anode 11 that had been immersed in the monomer solution in the oxidant solution for 30 seconds. Soaked across. As a result, the monomer contained in the monomer solution is chemically oxidatively polymerized using an oxidizing agent to produce polyethylenedioxythiophene as a conductive polymer, and the conductive polymer doped with the dopant. A solid electrolyte layer 13 containing was formed so as to cover the dielectric layer 12. When the solid electrolyte layer 13 is formed, the above-described procedure for forming the solid electrolyte layer 13 is repeated 10 times, and in particular, by washing the solid electrolyte layer 13 with water each time the chemical oxidation polymerization reaction is completed, unreacted Monomer, excess dopant or spent oxidant was removed as needed.

  Subsequently, the carbon layer 14A is formed to have a thickness of 10 μm by applying a carbon paste around the solid electrolyte layer 13 and drying, and further applying a silver paste on the carbon layer 14A and drying. Thus, the silver layer 14B was formed to a thickness of 30 μm, and the cathode 14 was formed so as to have a two-layer structure in which the carbon layer 14A and the silver layer 14B were laminated in this order. Thereby, capacitor element 10 having a laminated structure in which anode 11, dielectric layer 12, solid electrolyte layer 13 and cathode 14 were laminated in this order was formed (see FIGS. 1 to 3).

  Subsequently, the copper anode lead and the cathode lead are connected to the capacitor element 10 using welding, and then the capacitor element 10 is subjected to an aging process by applying a voltage using the anode lead and the cathode lead. The anode 11 was anodized. Finally, the electrolytic capacitor was completed by covering the capacitor element 10 with the epoxy resin as the mold resin so that the anode lead and the cathode lead are partially exposed.

  In order to investigate the operating characteristics of the electrolytic capacitor manufactured using the above-described electrolytic capacitor manufacturing method, the composition of the pretreatment solution, the pretreatment temperature and time, the composition of the chemical solution, and the chemical treatment temperature And the processing time was set as follows to produce a series of electrolytic capacitors.

(Example 1)
A pretreated aluminum foil having a capacitance of 78 μF / cm ² and a rated film withstand voltage of 23 V was used, and a diammonium adipate aqueous solution was used as a pretreatment solution. The concentration of the pretreatment solution was 15% by weight, pretreatment The electrolytic capacitor was manufactured at a treatment temperature of 25 ° C., a treatment time of 40 hours, a concentration of the chemical conversion solution of 7% by weight, a treatment temperature of the chemical conversion treatment of 70 ° C., and a treatment time of 2 minutes. At this time, the size of the capacitor region = 15 mm × 15 mm, the applied voltage at the time of chemical conversion treatment = 23 V, the rated voltage of the electrolytic capacitor = 6.3 V, and the high temperature and high humidity environment (temperature = 110 ° C., humidity = 85) as the aging treatment. %), The applied voltage was increased stepwise from 0V to 14V.

(Example 2)
An electrolytic capacitor was manufactured through the same procedure as in Example 1 except that distilled water was used as the pretreatment solution and the pretreatment treatment temperature was 25 ° C.

(Example 3)
An electrolytic capacitor was manufactured through the same procedure as in Example 1 except that boiling distilled water was used as the pretreatment solution, the pretreatment treatment temperature was 100 ° C., and the pretreatment treatment time was 1 hour.

Example 4
A pretreated aluminum foil having a capacitance of 363 μF / cm ² and a rated film withstand voltage of 4 V is used, and boiling distilled water is used as a pretreatment solution. Pretreatment treatment temperature = 100 ° C., treatment time = 1 hour The electrolytic capacitor was manufactured by setting the concentration of the chemical conversion solution = 7% by weight, the processing temperature of the chemical conversion treatment = 70 ° C., and the processing time = 2 minutes. At this time, the size of the capacitor region = 15 mm × 1.2 mm, the applied voltage at the time of chemical conversion treatment = 4 V, the rated voltage of the electrolytic capacitor = 2.5 V, and the aging treatment in a high temperature and high humidity environment (temperature = 110 ° C.) The applied voltage was raised stepwise from 0V to 2.2V.

(Comparative Example 1)
Unlike Examples 1 to 3 in which the pretreatment was performed using the pretreatment solution, electrolytic capacitors were manufactured through the same procedure as in Examples 1 to 3 except that the pretreatment was not performed.

(Comparative Example 2)
Unlike Example 4 in which the pretreatment was performed using the pretreatment solution, an electrolytic capacitor was manufactured through the same procedure as in Example 4 except that the pretreatment was not performed.

  When the operating characteristics of the electrolytic capacitors of Examples 1 to 4 and Comparative Examples 1 and 2 described above were examined, the results shown in Tables 1 to 4 were obtained. Tables 1 to 4 show the operating characteristics of the electrolytic capacitors, Table 1 shows the comparison results of Example 1 and Comparative Example 1, Table 2 shows the comparison results of Example 2 and Comparative Example 1, and Table 3 Shows the comparison results of Example 3 and Comparative Example 1, and Table 4 shows the comparison results of Example 4 and Comparative Example 2. In these Tables 1 to 4, as the operating characteristics of the electrolytic capacitor, “leakage current characteristics” are shown together with “capacity” at 120 Hz and “tan δ (so-called dielectric loss)”. The “leakage current characteristics” include the “leakage current (μA)” after the aging process and the operating characteristics of the electrolytic capacitor based on the leakage current as “◎ (leakage current <1 μA)” and “◯ (1 μA ≦ leakage). The result (“Evaluation”) of “current <50 μA)” or “× (leakage current ≧ 50 μA)” is shown. In particular, for Example 4 and Comparative Example 2, only “leakage current (μA)” and “evaluation” after aging treatment are shown, while for Examples 1-3 and Comparative Example 1, after aging treatment. Considering that the leakage current of the electrolytic capacitor changes over time due to the influence of residual moisture, together with “leakage current (μA)” and “evaluation” after aging treatment, 120 hours after aging treatment “Leakage current (μA)” and “Evaluation” are also shown. When investigating the leakage current of the electrolytic capacitor, with respect to Examples 1 to 3 and Comparative Example 1, the leakage current was measured after applying the rated voltage = 6.3 V for 5 minutes. Regarding Example 2, the leakage current is measured after applying the rated voltage = 2.5 V for 5 minutes, especially when applying the rated voltage to the electrolytic capacitor to suppress rapid charging in any case. A protective resistance (= 1 kΩ) was used for this purpose.

  When examining the operating characteristics of the electrolytic capacitor, the capacitor element 10 is used as a simple electrolytic capacitor shown in FIG. 10 in place of the finished electrolytic capacitor in order to investigate the operating characteristics in a simple and highly accurate manner. Used to perform an operating characteristic test. In the capacitor element 10 shown in FIG. 10, test leads 15 and 16 for testing are connected to the anode 11 and the cathode 14, respectively, instead of the anode lead and the cathode lead, and the anode 11 and the cathode 14 are insulated from each other. Therefore, it has the same structure as the capacitor element 10 shown in FIGS. 1 to 3 except that the anode 11 is provided with an insulating layer 17 (for example, silicon resin). In addition to being used as an electrode for driving the capacitor element 10 finally, the test lead 15 is used as an electrode at the time of chemical conversion treatment in the manufacturing process of the capacitor element 10. The insulating layer 17 is not limited to the capacitor element 10 shown in FIG. 10, for example, in order to prevent the chemical conversion solution from creeping up to the anode 11 due to the capillary phenomenon. May also be provided.

  As can be seen from the results shown in Table 1, in the electrolytic capacitor of Example 1 that was pretreated using a diammonium adipate aqueous solution as the pretreatment solution, the leakage current was 0.86 μA (evaluation = ◎) In addition, the electrolytic capacitor of Comparative Example 1 in which the pretreatment was not performed was 0.85 μA (evaluation = ◎) after an additional 120 hours, but the leakage current was 0.24 μA (after the aging treatment). Evaluation = ◯), and further after lapse of 120 hours, it was 370 μA (evaluation = ×). That is, in the electrolytic capacitor of Example 1, the occurrence of leakage current was suppressed after the aging treatment, and the suppression state of the leakage current was maintained over time, whereas in the electrolytic capacitor of Comparative Example 1, Although the generation of leakage current was temporarily suppressed after the aging treatment, the state of suppression of the leakage current was not maintained over time, that is, the leakage current increased over time. This is because in the electrolytic capacitor of Example 1, the dielectric layer portions 12C and 12D were formed with high quality so as to sufficiently cover the exposed surfaces PC and PD of the anode 11 by the pretreatment, whereas the comparative example In the electrolytic capacitor 1, the dielectric layer portions 12C and 12D were not formed so as to sufficiently cover the exposed surfaces PC and PD of the anode 11, and the dielectric layer portions 12C and 12D were not formed with high quality. it is conceivable that. From this, unlike the electrolytic capacitor of Comparative Example 1, the electrolytic capacitor of Example 1 suppresses the generation of leakage current based on the high quality of the dielectric layer 12, so that the operation characteristics are stably secured. It was confirmed that

  Subsequently, as can be seen from the results shown in Table 2, in the electrolytic capacitor of Example 2 that was pretreated using distilled water as a pretreatment solution, the leakage current was 3.73 μA (evaluation = ○), and after an additional 120 hours, it was 3.71 μA (evaluation = ◯). That is, in the electrolytic capacitor of Example 2, like the electrolytic capacitor of Example 1 described above, the generation of leakage current was suppressed after the aging treatment, and the suppression state of the leakage current was maintained over time. This is considered to be because in the electrolytic capacitor of Example 2, the dielectric layer portions 12A and 12B were repaired by the pretreatment, and the quality of the dielectric layer portions 12A and 12B was improved. From this, also in the electrolytic capacitor of Example 2, since generation | occurrence | production of the leakage current was suppressed based on quality improvement of the dielectric material layer 12, it was confirmed that an operating characteristic is ensured stably.

  Subsequently, as can be seen from the results shown in Table 3, in the electrolytic capacitor of Example 3 that was pretreated using boiling distilled water as the pretreatment solution, the leakage current was 0.95 μA (evaluation after the aging treatment) = ◎), and further after 120 hours, it was 41.53 μA (evaluation = ◯). That is, in the electrolytic capacitor of Example 3, like the electrolytic capacitor of Example 1 described above, the generation of leakage current was suppressed after the aging treatment, and the suppression state of the leakage current was maintained over time. This is because, in the electrolytic capacitor of Example 3, as in the electrolytic capacitor of Example 2 described above, the dielectric layer portions 12A and 12B are formed by utilizing the repairing action of the dielectric layer portions 12A and 12B based on the pretreatment. This is thought to be due to high quality. From this, also in the electrolytic capacitor of Example 3, since generation | occurrence | production of the leakage current was suppressed based on quality improvement of the dielectric material layer 12, it was confirmed that an operating characteristic is ensured stably.

  Finally, as can be seen from the results shown in Table 4, in the electrolytic capacitor of Example 4 which was pretreated using boiling distilled water as the pretreatment solution, the leakage current was 0.11 μA (evaluation after aging treatment) = ◎). Note that, in the electrolytic capacitor of Comparative Example 2 that was not subjected to the pretreatment, the leakage current was 35.11 μA (evaluation = ◯) after the aging treatment. That is, also in the electrolytic capacitor of Example 4, generation of leakage current was suppressed after the aging treatment, and the suppression state of the leakage current was maintained over time. From this, also in the electrolytic capacitor of Example 4, since generation | occurrence | production of the leakage current was suppressed based on quality improvement of the dielectric material layer 12, it was confirmed that an operating characteristic is ensured stably.

  While the present invention has been described with reference to the embodiments and examples, the present invention is not limited to these embodiments and examples, and various modifications can be made.

  Specifically, in the first embodiment and examples, an electrolyte typified by borate, phosphate, or adipate is used as a pretreatment solution for promoting the anodic oxidation reaction of the anode 11. However, the present invention is not necessarily limited to this. As long as it is possible to promote the anodic oxidation reaction of the anode 11 by performing the pretreatment using the pretreatment solution, the electrolyte solution of the electrolyte is used. The type can be changed freely. Even in this case, the same effects as those of the first embodiment and examples can be obtained.

  In the second embodiment and examples, water represented by distilled water or boiling water is used as a pretreatment solution for repairing the dielectric layer portions 12A and 12B. However, the present invention is not limited to this. As long as it is possible to repair the dielectric layer portions 12A and 12B by performing a pretreatment using a pretreatment solution, a liquid other than the water may be used. Good. Even in this case, the same effects as those of the second embodiment and examples can be obtained.

  The method for manufacturing an electrolytic capacitor according to the present invention can be applied to a manufacturing process of a solid electrolytic capacitor in which a main part that generates an electrical reaction is composed of a solid material (conductive polymer).

It is an external view showing the external appearance structure of the principal part (capacitor element) of the electrolytic capacitor manufactured using the manufacturing method of the electrolytic capacitor which concerns on the 1st Embodiment of this invention. It is sectional drawing which expands and represents the cross-sectional structure along the II-II line of the capacitor | condenser element shown in FIG. FIG. 3 is a cross-sectional view illustrating a partially enlarged cross-sectional configuration of the capacitor element illustrated in FIG. 2. It is a flowchart for demonstrating the flow of the manufacturing process in the manufacturing method of the electrolytic capacitor which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the composition of a series of solutions (Pretreatment solution, chemical conversion solution, monomer solution, oxidizing agent solution) used in the manufacturing method of the electrolytic capacitor concerning a 1st embodiment of the present invention. . It is sectional drawing showing the cross-sectional structure of the anode before chemical conversion treatment used in the manufacturing method of the electrolytic capacitor which concerns on the 1st Embodiment of this invention. It is sectional drawing showing the cross-sectional structure of the anode after chemical conversion treatment. It is a figure for demonstrating the modification regarding the manufacturing method of the electrolytic capacitor which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the composition of a series of solutions (Pretreatment solution, chemical conversion solution, monomer solution, oxidizing agent solution) used in the manufacturing method of the electrolytic capacitor concerning the 2nd Embodiment of the present invention. . It is an external view showing the external appearance structure of the electrolytic capacitor (capacitor element) for a test.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Capacitor element, 11 ... Anode, 12 ... Dielectric layer, 12A-12D ... Dielectric layer part, 13 ... Solid electrolyte layer, 14 ... Cathode, 14A ... Carbon layer, 14B ... Silver layer, 15, 16 ... Test lead , 17 ... insulating layer, PA, PB ... surface (covered surface), PC, PD ... surface (exposed surface).

Claims (11)

This is an electrolytic capacitor manufacturing method having a laminated structure in which an electrode layer made of a valve metal, a dielectric layer formed by anodizing the electrode layer, and a solid electrolyte layer are laminated in this order. And
Using the pretreatment solution for promoting the anodic oxidation reaction of the electrode layer, pretreating the electrode layer, and then anodizing the electrode layer using a chemical conversion solution, the dielectric layer The manufacturing method of the electrolytic capacitor characterized by including the process of forming. Forming the dielectric layer comprises:
A first step of preparing the electrode layer in which a first dielectric layer portion constituting a part of the dielectric layer is partially formed in advance;
A second step of pretreating the electrode layer using the pretreatment solution;
By using the chemical conversion solution and anodizing the pretreated electrode layer to form a second dielectric layer portion that constitutes another part of the dielectric layer, these first and first A method of manufacturing an electrolytic capacitor according to claim 1, further comprising: a third step of forming the dielectric layer so as to cover the periphery of the electrode layer including two dielectric layer portions. The method for producing an electrolytic capacitor according to claim 2, wherein, in the second step, an electrolyte solution is used as the pretreatment solution, and the electrode layer is immersed in the electrolyte solution. The method for producing an electrolytic capacitor according to claim 3, wherein the chemical conversion solution is used as the electrolyte solution. The method for producing an electrolytic capacitor according to any one of claims 1 to 4, wherein the concentration of the pretreatment solution is higher than the concentration of the chemical conversion solution. In the first step, after the first dielectric layer portion is formed as the electrode layer so as to cover the periphery of the electrode layer, the electrode layer is cut together with the first dielectric layer portion. An electrolytic capacitor manufacturing method according to any one of claims 2 to 5, wherein an electrolytic capacitor is prepared. This is an electrolytic capacitor manufacturing method having a laminated structure in which an electrode layer made of a valve metal, a dielectric layer formed by anodizing the electrode layer, and a solid electrolyte layer are laminated in this order. And
The pretreatment solution for repairing the dielectric layer is used to pretreat the electrode layer, and then the electrode layer is anodized using a chemical conversion solution to form the dielectric layer. The manufacturing method of the electrolytic capacitor characterized by including a process. Forming the dielectric layer comprises:
A first step of preparing the electrode layer in which a first dielectric layer portion constituting a part of the dielectric layer is partially formed in advance;
A second step of pretreating the electrode layer using the pretreatment solution;
By using the chemical conversion solution and anodizing the pretreated electrode layer to form a second dielectric layer portion that constitutes another part of the dielectric layer, these first and first A method of manufacturing an electrolytic capacitor according to claim 7, further comprising: a third step of forming the dielectric layer so as to cover the periphery of the electrode layer including the two dielectric layer portions. The method for producing an electrolytic capacitor according to claim 8, wherein in the second step, water is used as the pretreatment solution, and the electrode layer is immersed in the water. The method for manufacturing an electrolytic capacitor according to claim 9, wherein boiling water is used as the water. In the first step, after the first dielectric layer portion is formed as the electrode layer so as to cover the periphery of the electrode layer, the electrode layer is cut together with the first dielectric layer portion. The method for producing an electrolytic capacitor according to any one of claims 8 to 10, wherein a capacitor is prepared.

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