Manufacturing method of electrolytic capacitor

Abstract

To provide a manufacturing method of an electrolytic capacitor capable of suppressing short circuits between an anodizing solution and an anode electrode during the chemical conversion treatment of an anode body.SOLUTION: A disclosed manufacturing method of an electrolytic capacitor is a manufacturing method of an electrolytic capacitor that includes; an anode part including an anode body 1; a cathode part; and a dielectric layer formed on the surface of the anode body. The manufacturing method includes a chemical conversion step of oxidizing at least part of the surface of the anode body 1 to form a dielectric layer by performing a chemical conversion treatment of the anode body 1 in a chemical conversion solution 102 in which a porous body 106 is immersed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrolytic capacitor. [Background technology]

[0002] An electrolytic capacitor includes an anode body and a dielectric layer formed on the surface of the anode body. In general, the dielectric layer is formed by anodizing the surface of the anode body (chemical conversion treatment).

[0003] Patent Document 1 discloses a method for manufacturing a solid electrolytic capacitor, which includes the steps of providing an anode lead to an anode body to form a capacitor element, pouring a chemical conversion solution into a chemical conversion tank and floating a plurality of beads having a heat insulating effect on the surface of the chemical conversion solution to cover the surface of the chemical conversion solution with the beads, and immersing the anode body in the chemical conversion solution through the beads and passing a current through the anode lead to form a dielectric oxide film on the surface of the anode body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-56035 Summary of the Invention [Problem to be solved by the invention]

[0005] When anodizing the anode body, water is electrolyzed on the cathode side, generating hydrogen. The generated hydrogen is initially absorbed into the chemical conversion solution, but when it becomes unable to dissolve in the chemical conversion solution, bubbles containing hydrogen gas reach the liquid surface. When the bubbles burst, the chemical conversion solution is scattered onto and adheres to the carrier bar that applies voltage to the anode body, which can cause a short circuit between the carrier bar and the chemical conversion solution. The short-circuit current reduces the amount of current that should flow through the anode body, which can result in longer chemical conversion times or in incomplete formation of a dielectric oxide film.

[0006] In addition, the short-circuit current may cause metal components (e.g., aluminum) contained in the carrier bar to dissolve into the chemical conversion solution, causing the metal components to become mixed into the anode body and resulting in a decrease in the characteristics of the electrolytic capacitor, such as an increase in leakage current.

[0007] In response to this problem, it is possible to prevent short circuits between the carrier bar and the chemical conversion solution due to the bursting of bubbles by floating beads as described in Patent Document 1. However, the beads become an obstacle when the anode body is immersed in the chemical conversion solution or when the anode body is removed from the chemical conversion solution. In addition, the beads may adhere to the anode body after it is removed from the chemical conversion solution, reducing workability. [Means for solving the problem]

[0008] One aspect of the present disclosure relates to a method for manufacturing an electrolytic capacitor including an anode part including an anode body, a cathode part, and a dielectric layer formed on a surface of the anode body, the method including a chemical treatment step of performing chemical conversion treatment of the anode body in a chemical conversion solution in which a porous body is immersed, thereby oxidizing at least a portion of the surface of the anode body and forming the dielectric layer. [Effects of the Invention]

[0009] According to the present disclosure, short-circuiting between the chemical conversion solution and the anode electrode during chemical conversion treatment is suppressed, and the formation of a dielectric layer by chemical conversion treatment of the anode body can be performed without reducing workability. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram illustrating a schematic view of the state in a chemical conversion tank during chemical conversion treatment, illustrating an example of the manufacturing method of the present disclosure. [Figure 2] FIG. 1 is a cross-sectional view schematically illustrating an example of a capacitor element of an electrolytic capacitor manufactured by the manufacturing method of the present disclosure. [Figure 3] FIG. 1 is a cross-sectional view schematically illustrating an example of an electrolytic capacitor manufactured by the manufacturing method of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the manufacturing method according to the present disclosure will be described using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure are obtained. In this specification, the expression "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "numerical value A or more and numerical value B or less."

[0012] <Manufacturing method of electrolytic capacitors> The method of the present embodiment for manufacturing an electrolytic capacitor is a method for manufacturing an electrolytic capacitor including an anode part including an anode body, a cathode part, and a dielectric layer formed on the surface of the anode body, and includes a chemical conversion treatment step of performing chemical conversion treatment on the anode body in a chemical conversion solution in which a porous body is immersed, thereby oxidizing at least a portion of the surface of the anode body to form the dielectric layer. From another perspective, the manufacturing method is a method for manufacturing a member of an electrolytic capacitor (an anode body having a dielectric layer formed on its surface).

[0013] By performing chemical conversion treatment in a solution in which the porous body is immersed, bubbles generated on the cathode side become smaller, and even if the bubbles reach the liquid surface and burst, scattering of the chemical conversion solution is suppressed, and short-circuiting between the anode electrode connected to the anode body and the chemical conversion solution is suppressed.

[0014] During the chemical conversion treatment, the surface of the anode body is oxidized on the anode side, forming a dielectric oxide film, while water is electrolyzed on the cathode side, generating hydrogen. The generated hydrogen can dissolve in the chemical conversion solution, but hydrogen that cannot be completely dissolved in the chemical conversion solution forms bubbles and rises to the liquid surface. The bubbles can contain oxygen, nitrogen, and other elements in addition to hydrogen.

[0015] When a porous body is present in the anodizing tank, bubbles grow on the surface of the porous body with its pores and rise to the surface. The bubbles grow along the minute recesses created by the pores, and when they reach a certain diameter, they detach from the porous body and rise to the surface. Therefore, the size (diameter) of the bubbles when they rise corresponds to the pore diameter of the porous body. As a result, the bubbles rise to the surface of the anodizing solution in the form of fine bubbles, which reduces the scattering of the anodizing solution when the bubbles burst during the rise, and prevents short circuits between the anodizing solution and the anode electrode.

[0016] The material of the porous body is not particularly limited, but may be at least one selected from the group consisting of ceramics, carbon materials, the metals used in the anode body, resins, and glass. The anode body of an electrolytic capacitor may be immersed in a chemical conversion tank without being electrically connected to the anode electrode for power supply and used as a porous body. Ceramics, carbon materials, metals, resins, glass, etc. may be molded or sintered bodies of at least one of the respective powders. Ceramics may be molecular sieve materials such as zeolite and mesoporous silica. The carbon material may be activated carbon.

[0017] The porous body preferably has three-dimensionally extending interconnected pores (pores) and a three-dimensional network structure. The pore size of the porous body is preferably 10 μm or less, and the specific surface area (BET specific surface area) is preferably 0.5 m or less. 2 / g or more is preferred.

[0018] The chemical conversion treatment step includes, for example, a step (i) of electrically connecting the anode body to a first electrode (anode electrode), and a step (ii) of oxidizing at least a portion of the surface of the anode body by applying a DC voltage between the first electrode and a second electrode (cathode electrode) while the anode body electrically connected to the first electrode is immersed in a chemical conversion solution in a chemical conversion tank, thereby forming a dielectric layer.

[0019] (Step (i)) First, the anode body is electrically connected to the first electrode. For example, when the anode section has a porous anode body and an anode wire implanted from the implantation surface, which is one of the main surfaces of the anode body, the anode wire is connected to the first electrode. This electrically connects the anode body to the first electrode via the anode wire. There are no limitations on the anode body and anode wire, and known anode bodies and anode wires may be used. Alternatively, the anode section may be fabricated by a known method. Examples of anode bodies and anode wires, and examples of methods for forming them, will be described later.

[0020] In this case, the multiple anode bodies are arranged at intervals along a predetermined direction to form an anode body group, and each of the anode bodies in the anode body group is electrically connected to a first electrode. For example, if the anode unit has an anode wire, the multiple anode units are arranged at intervals along the predetermined direction, and each of the multiple anode wires connected to the multiple anode bodies is connected to the first electrode. The multiple anode units may be arranged in a line or in a matrix. The intervals at which the multiple anode units are arranged may be the same for all anode units, or the intervals between one anode unit and its adjacent anode unit may be different from the others.

[0021] The shape of the first electrode is selected depending on the arrangement of the anode body group. For example, when a plurality of anode bodies are arranged in a row, the first electrode may have a linear shape (e.g., a rod or plate shape). When a plurality of anode bodies are arranged in a matrix, the first electrode may be composed of a plurality of linear electrodes or may be a lattice-shaped electrode. The first electrode and the anode wire are electrically connected. Typically, the anode wire is fixed to the first electrode by a method such as welding. There are no particular limitations on the material of the first electrode, and it may be a conductive metal (e.g., iron, iron alloy, aluminum, etc.).

[0022] Metallic aluminum and its alloys are preferably used for the first electrode because they are lightweight and easy to work with. However, metallic aluminum and its alloys react with the chemical conversion solution and are prone to corrosion. Aluminum ions dissolved in the chemical conversion solution can easily penetrate into the anode body, degrading the performance of the electrolytic capacitor. However, by placing a porous body in the chemical conversion tank, the chemical conversion solution is prevented from scattering and adhering to the first electrode. As a result, a short circuit between the first electrode and the electrolytic solution is prevented. This prevents metallic aluminum from reacting with the chemical conversion solution and dissolving, thereby suppressing a degradation in the performance of the electrolytic capacitor.

[0023] The number of anode bodies included in the anode body group is not limited, and may be in the range of 10 to 200 (for example, in the range of 40 to 100). The interval between adjacent anode bodies is also not particularly limited, and the interval may be in the range of 1 to 20 mm (for example, in the range of 2 to 6 mm). Usually, the interval is constant, but the interval does not have to be constant.

[0024] (Step (ii)) Next, while the anode body electrically connected to the first electrode is immersed in the chemical conversion solution in the chemical conversion tank, a DC voltage is applied between the first electrode and the second electrode, thereby oxidizing (anodizing) at least a portion of the surface of the anode body and forming a dielectric layer.

[0025] In step (ii), the surface of the anode body is oxidized and converted into a dielectric layer. For example, if the anode body is made of tantalum, a tantalum oxide layer is formed on the surface of the anode body. The chemical conversion solution is not particularly limited, and a known chemical conversion solution used in chemical conversion treatment of anode bodies for electrolytic capacitors may be used. For example, the chemical conversion solution may be any of an acidic aqueous solution, a neutral aqueous solution, and a basic aqueous solution. Examples of acidic aqueous solutions include an aqueous solution of phosphoric acid, an aqueous solution of nitric acid, an aqueous solution of acetic acid, and an aqueous solution of sulfuric acid. Other examples of chemical conversion solutions include an aqueous solution of tartrate, an aqueous solution of oxalate, and an aqueous solution of tetraborate.

[0026] The second electrode is placed so as to be in contact with the chemical conversion solution. For example, the second electrode may be immersed in the chemical conversion solution. Alternatively, at least a part of the electrolytic cell in which the chemical conversion solution is placed may be used as the second electrode. The second electrode is preferably made of a metal that is stable during chemical conversion. Examples of materials for the second electrode include iron alloys, nickel, chromium, gold, platinum, tantalum, titanium, and carbon. The second electrode may be in the form of a plate or a mesh.

[0027] A porous body is immersed in the chemical conversion solution. The porous body may be provided at the bottom of the chemical conversion tank, or may be provided at any position between the liquid level of the chemical conversion solution and the bottom of the chemical conversion tank. The porous body may or may not be in contact with the second electrode. The porous body may be in contact with the second electrode on the surface of the second electrode facing the liquid level of the chemical conversion solution (i.e., facing the anode body group).

[0028] The second electrode can be disposed so as to be in contact with the chemical conversion solution and along the anode body group.

[0029] On the other hand, the porous body is preferably placed in a position that does not block the straight line connecting the anode body and the second electrode so as not to interfere with the electric field formed between the first electrode and the second electrode.

[0030] The porous body being in a position that does not block the straight line connecting the anode body and the second electrode means that the following condition is satisfied. Consider point P on the surface of the anode body. Find point Q on the surface of the second electrode that is the shortest distance from point P to the second electrode. For any point P on the surface of the anode body, find point Q on the surface of the second electrode that corresponds to point P, and consider the group of straight lines formed by the collection of straight lines PQ. If the porous body does not overlap (intersect) with any of the straight lines PQ included in this group of straight lines, the porous body is in a position that does not obstruct the straight lines connecting the anode body and the second electrode. In other words, when the space formed by this group of straight lines is S, the fact that the porous body does not obstruct the straight lines connecting the anode body and the second electrode also means that the space occupied by the porous body does not overlap with space S.

[0031] According to the above definition, the porous body being located in a position that does not obstruct the straight line connecting the anode body and the second electrode means, particularly when the second electrode extends in a direction parallel to the liquid surface of the chemical conversion solution, that the porous body is located in a position that does not overlap with the second electrode when viewed from a direction perpendicular to the liquid surface of the chemical conversion solution.

[0032] The porous body may be disposed along at least a portion of the sidewall of the chemical conversion tank or on the bottom of the chemical conversion tank so as not to interfere with the electric field formed between the first electrode and the second electrode. The porous body may be disposed on the circulation path of the chemical conversion solution, for example, in a pipe or pump for circulating the chemical conversion solution, or in a chemical conversion solution tank for preparing the electrolyte solution.

[0033] FIG. 1 is a schematic diagram illustrating the chemical conversion step of the manufacturing method for an electrolytic capacitor according to this embodiment, showing the state inside a chemical conversion tank 101 when a DC voltage is applied between a first electrode 104 and a second electrode 105 to perform chemical conversion. A plurality of anode parts, each having an anode body 1 and an anode wire 2, are arranged at regular intervals along a first electrode (anode) 104 and are electrically connected to the first electrode 104 via the anode wire 2. Each anode body 1 in the plurality of anode parts is immersed in a chemical conversion solution 102 and is in contact with the chemical conversion solution 102. The first electrode 104 extends in a direction parallel to the liquid surface 102a of the chemical conversion solution 102 and is also called a carrier bar. The arrangement direction of the plurality of anode parts is the same as the extension direction of the first electrode 104 and is parallel to the liquid surface 102a of the chemical conversion solution 102.

[0034] A second electrode (cathode electrode) 105 is disposed at the bottom of the anodizing tank 101. The second electrode 105 is in contact with the anodizing solution 102. The second electrode 105 extends in a direction parallel to a liquid surface 102a of the anodizing solution 102 within the anodizing tank 101. A porous body 106 is disposed within the anodizing tank 101. The porous body 106 is disposed at a position deviated from the straight line connecting the anode body 1 and the second electrode 105 (i.e., at a position that does not overlap with the second electrode 105 when viewed from a direction perpendicular to the liquid surface 102a of the anodizing solution).

[0035] When a DC voltage is applied between the first electrode 104 and the second electrode 105, the surface of the anode body 1 is oxidized, forming a dielectric oxide film. Meanwhile, on the cathode side, water in the chemical conversion solution 102 electrically connected to the second electrode 105 is electrolyzed, generating hydrogen. The generated hydrogen initially dissolves in the chemical conversion solution, but when it becomes insoluble, it grows on the surface of the porous body 106 and turns into fine bubbles 103 corresponding to the pore size of the porous body 106. The bubbles 103 rise within the chemical conversion tank 101 and reach the liquid surface 102a of the chemical conversion solution. This prevents the chemical conversion solution 102 from scattering when the bubbles 103 reach the liquid surface 102a, thereby preventing a short circuit between the chemical conversion solution 102 and the first electrode 104.

[0036] The shorter the distance between the first electrode and the chemical conversion solution surface, the more likely it is that the chemical conversion solution will adhere to the first electrode when bubbles reach the surface, causing a short circuit between the chemical conversion solution and the first electrode. Because the material for the anode wire is expensive, shortening the length of the anode wire (the length of the part that extends from the anode body) is considered to reduce costs. However, the shorter the anode wire, the shorter the distance between the first electrode and the chemical conversion solution surface during the chemical conversion treatment process. This causes the chemical conversion solution to splash when bubbles reach the surface, making it more likely that the chemical conversion solution will short-circuit between the chemical conversion solution and the first electrode.

[0037] According to the method for manufacturing an electrolytic capacitor of this embodiment, even when the anode wire is shortened, which results in a shorter distance between the first electrode and the chemical conversion solution surface, scattering of the chemical conversion solution when bubbles reach the solution surface is suppressed, and short-circuiting between the chemical conversion solution and the first electrode is suppressed. This prevents degradation of the electrolytic capacitor's performance due to components of the first electrode penetrating into the anode body.

[0038] In the step (ii), the distance between the first electrode and the surface of the chemical conversion solution may be 10 mm or less, or may be 5 mm or less.

[0039] The process including steps (i) and (ii) provides an anode part having a dielectric layer formed on its surface. Therefore, in one aspect, the present disclosure provides a method for manufacturing an anode part having a dielectric layer formed on its surface. The manufacturing method includes the above-mentioned steps (i) and (ii).

[0040] After the step (ii), the electrolytic capacitor is obtained by carrying out the steps of forming the necessary parts of the electrolytic capacitor. These steps are not limited, and known methods may be used.

[0041] In one example of a manufacturing method for an electrolytic capacitor in which the anode body is a sintered body, an electrolyte layer is formed on a dielectric layer, and a cathode portion is formed on the electrolyte layer. In this manner, a capacitor element is produced. Next, an anode lead terminal is connected to the anode wire, and a cathode lead terminal is connected to the cathode portion. Finally, an exterior body is formed to cover the capacitor element, a portion of the anode lead terminal, and a portion of the cathode lead terminal. In this manner, an electrolytic capacitor is obtained.

[0042] In one example of a method for manufacturing an electrolytic capacitor in which the anode body is a wound body of metal foil, in step (i), a wound body is prepared by winding an anode body (metal foil), a separator, and a cathode foil. The wound body includes an anode portion. The anode portion includes the anode body (metal foil) and an anode wire protruding from a first end face of the anode body (the first end face of the wound anode body). Typically, a dielectric layer is formed on the surface of the anode body (metal foil), but the dielectric layer is not formed on at least a portion of the end face of the anode body. Therefore, to form a dielectric layer in the portion where the dielectric layer is not formed, a dielectric layer is formed in step (ii) above. After the dielectric layer is formed, an electrolyte layer is formed inside the wound body to produce a capacitor element. The produced capacitor element is enclosed in a case to obtain a wound electrolytic capacitor. The electrolyte layer may be a solid electrolyte layer or an electrolyte layer containing a liquid component. There are no particular limitations on the components and formation method, and known components and formation methods may be used.

[0043] <Electrolytic capacitor> As an example of the configuration and components of an electrolytic capacitor manufactured by the manufacturing method of the present disclosure, an example using a sintered anode body will be described below. The example electrolytic capacitor described below includes a capacitor element, an outer casing, an anode lead terminal, and a cathode lead terminal. Note that the configuration and components of an electrolytic capacitor manufactured by the method of the present disclosure are not limited to the following example.

[0044] Fig. 2 is a cross-sectional view schematically showing an example of a capacitor element of an electrolytic capacitor manufactured by the manufacturing method according to this embodiment. Fig. 3 is a cross-sectional view schematically showing an electrolytic capacitor manufactured by the manufacturing method according to this embodiment. However, the present invention is not limited to the configurations shown in these drawings.

[0045] Electrolytic capacitor 20 includes capacitor element 10 having anode portion 6 and cathode portion 7, exterior body 11 that seals capacitor element 10, anode lead terminal 13 electrically connected to anode portion 6 and partially exposed from exterior body 11, and cathode lead terminal 14 electrically connected to cathode portion 7 and partially exposed from exterior body 11. Anode portion 6 includes anode body 1 and anode wire 2. Dielectric layer 3 is formed on the surface of the anode body. Cathode portion 7 includes solid electrolyte layer 4 covering at least a portion of dielectric layer 3, and cathode layer 5 covering at least a portion of the surface of solid electrolyte layer 4.

[0046] (Capacitor element) Hereinafter, capacitor element 10 will be described in detail, taking as an example a case where a solid electrolyte layer is provided as the electrolyte.

[0047] (anode part) The anode part 6 has an anode body 1 and an anode wire 2 that extends from one surface of the anode body 1 and is electrically connected to an anode lead terminal 13 . The anode body 1 is, for example, a rectangular parallelepiped porous sintered body obtained by sintering metal particles. The metal particles used are particles of a valve metal such as titanium (Ti), tantalum (Ta), or niobium (Nb). The anode body 1 uses one or more types of metal particles. The metal particles may be an alloy made of two or more types of metal. For example, an alloy containing a valve metal and silicon, vanadium, boron, or the like may be used. Alternatively, a compound containing a valve metal and a typical element such as nitrogen may be used. The valve metal alloy contains the valve metal as the main component, for example, at least 50 atomic % of the valve metal.

[0048] The anode wire 2 is made of a conductive material. The material of the anode wire 2 is not particularly limited and includes, for example, the valve metals mentioned above, as well as niobium, aluminum, and aluminum alloys. The materials constituting the anode body 1 and the anode wire 2 may be the same or different. The anode wire 2 has a first portion 2a that is embedded inside the anode body 1 from one surface of the anode body 1, and a second portion 2b that extends from the above surface of the anode body 1. The cross-sectional shape of the anode wire 2 is not particularly limited and may be a circle, a track shape (a shape consisting of parallel straight lines and two curved lines connecting the ends of these lines), an ellipse, a rectangle, a polygon, etc.

[0049] The anode part 6 is produced, for example, by embedding the first portion 2a in a powder of particles of the first metal, press-molding the first portion 2a into a rectangular parallelepiped shape, and then sintering the resulting product. This causes the second portion 2b of the anode wire 2 to extend from one surface of the anode body 1 in an upright manner. The second portion 2b is joined to the anode lead terminal 13 by welding or the like, thereby electrically connecting the anode wire 2 and the anode lead terminal 13. The welding method is not particularly limited, and examples include resistance welding and laser welding.

[0050] A dielectric layer 3 is formed on the surface of the anode body 1. The dielectric layer 3 is made of, for example, a metal oxide. The dielectric layer 3 is formed by performing the chemical conversion treatment step described above, in which the anode body 1 is immersed in a chemical conversion solution and the surface of the anode body 1 is anodized.

[0051] (cathode) The cathode section 7 has a solid electrolyte layer 4 and a cathode layer 5 that covers the solid electrolyte layer 4. The solid electrolyte layer 4 is formed so as to cover at least a portion of the dielectric layer 3.

[0052] For example, a manganese compound or a conductive polymer is used for the solid electrolyte layer 4. Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, and polyacetylene. These may be used alone or in combination. The conductive polymer may also be a copolymer of two or more monomers. In terms of excellent conductivity, polythiophene, polyaniline, and polypyrrole may be used. In particular, in terms of excellent water repellency, polypyrrole may be used.

[0053] The solid electrolyte layer 4 containing the conductive polymer is formed, for example, by polymerizing a raw material monomer on the dielectric layer 3. Alternatively, it is formed by applying a liquid containing the conductive polymer to the dielectric layer 3. The solid electrolyte layer 4 is composed of one or more solid electrolyte layers. When the solid electrolyte layer 4 is composed of two or more layers, the composition and formation method (polymerization method) of the conductive polymer used in each layer may be different.

[0054] In this specification, polypyrrole, polythiophene, polyfuran, polyaniline, etc. refer to polymers having polypyrrole, polythiophene, polyfuran, polyaniline, etc. as their basic skeletons, respectively. Therefore, polypyrrole, polythiophene, polyfuran, polyaniline, etc. may also include their respective derivatives. For example, polythiophene includes poly(3,4-ethylenedioxythiophene).

[0055] Various dopants may be added to the polymerization solution for forming the conductive polymer, or the solution or dispersion of the conductive polymer in order to improve the conductivity of the conductive polymer. The dopant is not particularly limited, but examples thereof include naphthalenesulfonic acid, p-toluenesulfonic acid, and polystyrenesulfonic acid.

[0056] When the conductive polymer is dispersed in the dispersion medium in the form of particles, the particles have an average particle size D50 of, for example, 0.01 μm or more and 0.5 μm or less. If the average particle size D50 of the particles is within this range, the particles can easily penetrate into the interior of anode body 1.

[0057] The cathode layer 5 has, for example, a carbon layer 5a formed to cover the solid electrolyte layer 4 and a metal paste layer 5b formed on the surface of the carbon layer 5a. The carbon layer 5a contains a conductive carbon material such as graphite and a resin. The metal paste layer 5b contains, for example, metal particles (e.g., silver) and a resin. The configuration of the cathode layer 5 is not limited to this configuration. The configuration of the cathode layer 5 may be any configuration that has a current collecting function.

[0058] (Anode lead terminal) The anode lead terminal 13 is electrically connected to the anode body 1 via the second portion 2b of the anode wire 2. The material of the anode lead terminal 13 is not particularly limited as long as it is electrochemically and chemically stable and conductive. The anode lead terminal 13 may be made of a metal such as copper, or a non-metal. The shape of the anode lead terminal 13 is not particularly limited as long as it is flat. The thickness of the anode lead terminal 13 (the distance between the main surfaces of the anode lead terminal 13) may be 25 μm or more and 200 μm or less, or 25 μm or more and 100 μm or less, from the viewpoint of reducing the height.

[0059] One end of the anode lead terminal 13 may be joined to the anode wire 2 with a conductive adhesive or solder, or may be joined to the anode wire 2 by resistance welding or laser welding. The other end of the anode lead terminal 13 is led out of the exterior body 11 and exposed from the exterior body 11. The conductive adhesive is, for example, a mixture of a thermosetting resin (described later) with carbon particles or metal particles.

[0060] (cathode lead terminal) Cathode lead terminal 14 is electrically connected to cathode portion 7 at joint portion 14a. Joint portion 14a is a portion of cathode lead terminal 14 that overlaps with cathode layer 5 when cathode layer 5 and cathode lead terminal 14 joined to cathode layer 5 are viewed from the normal direction of cathode layer 5.

[0061] Cathode lead terminal 14 is joined to cathode layer 5 via, for example, conductive adhesive 8. One end of cathode lead terminal 14 constitutes, for example, part of joint portion 14a and is disposed inside exterior body 11. The other end of cathode lead terminal 14 is led out to the outside. Therefore, a part of cathode lead terminal 14, including the other end, is exposed from exterior body 11.

[0062] The material of the cathode lead terminal 14 is not particularly limited as long as it is electrochemically and chemically stable and conductive. The cathode lead terminal 14 may be made of a metal such as copper, or a non-metal. The shape of the cathode lead terminal 14 is also not particularly limited, and may be, for example, a long, flat plate. From the viewpoint of reducing the height, the thickness of the cathode lead terminal 14 may be 25 μm or more and 200 μm or less, or 25 μm or more and 100 μm or less.

[0063] (exterior body) The exterior body 11 is provided to electrically insulate the anode lead terminal 13 and the cathode lead terminal 14, and is made of an insulating material (exterior body material). The exterior body material includes, for example, a thermosetting resin. Examples of thermosetting resins include epoxy resin, phenol resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane, polyimide, and unsaturated polyester. [Industrial Applicability]

[0064] The present disclosure can be used in a method for manufacturing an electrolytic capacitor. [Explanation of symbols]

[0065] 20: Electrolytic capacitor 10: Capacitor element 1: Anode body 2: Anode wire 2a:First part 2b:Second part 3: Dielectric layer 4: Solid electrolyte layer 5: Cathode layer 5a: Carbon layer 5b: Metal paste layer 6: Anode part 7: Cathode 8: Conductive adhesive 11: Exterior body 12: Resin protective layer 13: Anode lead terminal 14: Cathode lead terminal 14a: Joint 101: Chemical tank 102: Chemical liquid 102a:Liquid level 103: Air bubbles 104: First electrode (anode electrode) 105: Second electrode (cathode electrode) 106: Porous material

Claims

1. A method for manufacturing an electrolytic capacitor including an anode part including an anode body, a cathode part, and a dielectric layer formed on a surface of the anode body, the method comprising: a chemical conversion treatment step of performing a chemical conversion treatment of the anode body in a chemical conversion solution in which a porous body is immersed, thereby oxidizing at least a part of a surface of the anode body to form the dielectric layer, The chemical conversion treatment step includes: (i) electrically connecting the anode body to a first electrode; and (ii) applying a DC voltage between the first electrode and the second electrode in a state in which the anode body electrically connected to the first electrode is immersed in the chemical conversion solution in a chemical conversion tank, thereby oxidizing at least a portion of a surface of the anode body to form the dielectric layer, the porous body is disposed at a position that does not block a straight line connecting the anode body and the second electrode.

2. The method for manufacturing an electrolytic capacitor according to claim 1 , wherein the porous body is disposed along at least a portion of a side wall surface of the chemical conversion bath.

3. The method for manufacturing an electrolytic capacitor according to claim 1 , wherein the porous body is placed on a bottom surface of the chemical conversion tank.

4. 4. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the first electrode contains aluminum.

5. 5. The method for manufacturing an electrolytic capacitor according to claim 1, wherein in the step (i), the plurality of anode bodies are arranged at intervals along a predetermined direction to form an anode body group, and each of the anode bodies in the anode body group is electrically connected to the first electrode.

6. the anode portion includes an anode wire embedded in the anode body, 6. The method for manufacturing an electrolytic capacitor according to claim 1, wherein in the step (i), the anode wire is connected to the first electrode.

7. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the porous body has three-dimensionally extending communicating pores.

8. 8. The method for producing an electrolytic capacitor according to claim 1, wherein the material of the porous body is at least one selected from the group consisting of ceramics, carbon materials, metals used in the anode body, resins, and glasses.

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