Electrolytic capacitor and method for manufacturing electrolytic capacitor

Abstract

The electrolytic capacitor includes an anode foil having a metal portion and a dielectric layer formed on a surface of the metal portion, a cathode foil, a separator interposed between the anode foil and the cathode foil, a conductive polymer layer formed on a surface of the dielectric layer and including a conductive polymer, and an anode lead connected to the anode foil. A part of the anode foil (21) has an exposed region (21R) exposed from the conductive polymer layer (24). The anode lead (60) is electrically connected to the anode foil (21) by being in direct contact with the metal portion (21a) in the exposed region (21R).

Description

Technical Field

[0001] This disclosure relates to electrolytic capacitors and methods for manufacturing electrolytic capacitors. Background Technology

[0002] Previously, electrolytic capacitors comprising an anode foil, a cathode foil, and a separator between the two were known (e.g., Patent Document 1). In the electrolytic capacitor of Patent Document 1, a conductive polymer layer is formed on the surface of the anode foil, and an anode lead is connected to the anode foil. The anode lead is led out to the outside of a housing containing the anode foil, etc., and functions as an external terminal of the electrolytic capacitor.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 2019-516241 Summary of the Invention

[0006] One aspect of this disclosure relates to an electrolytic capacitor. The electrolytic capacitor comprises: an anode foil having a metal portion and a dielectric layer formed on the surface of the metal portion; a cathode foil; a separator between the anode foil and the cathode foil; a conductive polymer layer formed on the surface of the dielectric layer and comprising a conductive polymer; and an anode lead connected to the anode foil. A portion of the anode foil has an exposed area that protrudes from the conductive polymer layer. The anode lead is electrically connected to the anode foil by direct contact with the metal portion in the exposed area.

[0007] Another aspect of this disclosure relates to a method for manufacturing an electrolytic capacitor, the electrolytic capacitor comprising an anode foil, a cathode foil, and a separator having a metal portion and a dielectric layer formed on the surface of the metal portion. The manufacturing method includes: a coating application step, applying a coating containing a conductive polymer and a liquid medium to the surface of the dielectric layer of the anode foil; a polymer layer formation step, forming a conductive polymer layer containing the conductive polymer on the surface of the dielectric layer by removing at least a portion of the liquid medium from the coating; a polymer layer removal step, forming an exposed area of ​​the anode foil exposed from the conductive polymer layer by removing a portion of the conductive polymer layer from a portion of the anode foil; and a lead connection step, electrically connecting the anode lead to the anode foil by directly contacting the metal portion in the exposed area with an anode lead.

[0008] According to this disclosure, the equivalent series resistance (ESR) of electrolytic capacitors can be reduced. Attached Figure Description

[0009] Figure 1This is a side view schematically illustrating an example of an electrolytic capacitor of the present disclosure.

[0010] Figure 2 It is a schematic exploded perspective view of a capacitor element.

[0011] Figure 3A This is a front view showing the area where the anode foil is connected to the anode lead.

[0012] Figure 3B It is a cross-sectional view showing the area where the anode foil is connected to the anode lead. Detailed Implementation

[0013] The following is a brief explanation of the problems in the existing technology.

[0014] Typically, the anode foil and anode leads are made of metal, with a conductive polymer layer sandwiched between them. The conductive polymer layer has lower conductivity than metal; therefore, the connection resistance between the anode foil and anode leads increases due to the presence of the conductive polymer layer, leading to a larger equivalent series resistance (ESR) of the electrolytic capacitor.

[0015] This disclosure provides an electrolytic capacitor capable of reducing ESR and a method for manufacturing an electrolytic capacitor.

[0016] The following description illustrates embodiments of the electrolytic capacitor and its manufacturing method according to the present disclosure. However, the present disclosure is not limited to the examples described below. Specific values ​​and materials are sometimes illustrated in the following description, but other values ​​and materials may be applied as long as the effects of the present disclosure are achieved.

[0017] (Manufacturing method of electrolytic capacitor)

[0018] The method for manufacturing an electrolytic capacitor disclosed herein is a method for manufacturing an electrolytic capacitor having an anode foil, a cathode foil, and a separator, wherein the anode foil has a metal portion and a dielectric layer formed on its surface, and the method for manufacturing an electrolytic capacitor includes a coating process, a polymer layer formation process, a polymer layer removal process, and a lead connection process.

[0019] (Coating process)

[0020] In the coating process, a coating solution comprising a conductive polymer and a liquid medium is applied (or coated) to the surface of the dielectric layer of the anode foil. The conductive polymer may be dispersed in the coating solution in the form of particles. The liquid medium may contain water and an organic compound. The organic compound may be a single compound or a combination of multiple compounds. There are no particular limitations on the method of applying the coating solution (or coating method), and it can be applied using known methods. For example, a coating machine can be used, the coating solution can be sprayed, or the anode foil can be impregnated in the coating solution. Examples of methods using a coating machine include gravure coating and die coating. In gravure coating, the coating solution is adhered to a transfer member such as a gravure roller. After excess coating solution is removed from the transfer member, the coating solution adhered to the transfer member is transferred to the anode foil, cathode foil, and diaphragm, respectively, thereby enabling a uniform thickness of coating solution to adhere to the anode foil, cathode foil, and diaphragm. Furthermore, the viscosity of the coating solution can be, for example, 10 mPa·s or more (or 100 mPa·s or more) and 200 mPa·s or less. In this case, the coating solution can be easily applied to the anode foil, cathode foil, and diaphragm, and can easily penetrate the diaphragm. It should be noted that the viscosity of the coating solution is determined at room temperature (20°C) using a vibratory viscometer (e.g., SEKONIC, VM-100A).

[0021] Examples of organic compounds may include at least one selected from polyols, sulfolane, γ-butyrolactone, and borate esters, or may be the same as the above-mentioned at least one. Organic compounds may include at least one selected from diols, glycerols, sugar alcohols, sulfolane, γ-butyrolactone, and borate esters, or may be the same as the above-mentioned at least one.

[0022] Examples of polyols include glycols, glycerols, and sugar alcohols. Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols (e.g., polyethylene glycol), and polyoxyethylene-polyoxypropylene glycol (ethylene oxide-propylene oxide copolymer). Examples of glycerols include glycerol and polyglycerol. Examples of sugar alcohols include mannitol, xylitol, sorbitol, erythritol, and pentaerythritol.

[0023] Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and their derivatives. These derivatives include polymers with polypyrrole, polythiophene, polyfuran, polyaniline, and polyacetylene as their basic backbone. For example, derivatives of polythiophene include poly(3,4-ethylenedioxythiophene). These conductive polymers can be used alone or in combination. Furthermore, conductive polymers can also be copolymers of two or more monomers. The weight-average molecular weight of conductive polymers is not particularly limited, and can, for example, range from 1,000 to 100,000. A preferred example of a conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0024] Conductive polymers can be doped with dopants. From the viewpoint of suppressing dedoping from conductive polymers, polymeric dopants are preferred as dopants. Examples of polymeric dopants include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polypropylene sulfonic acid, polymethyl methacrylate sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and polyacrylic acid. They can be used alone or in combination of two or more. At least a portion of them can be added in the form of salts. A preferred example of a dopant is polystyrene sulfonic acid (PSS). The weight-average molecular weight of the dopant is not particularly limited. From the viewpoint of easily forming a homogeneous conductive polymer layer, the weight-average molecular weight of the dopant can be set in the range of 1,000 to 100,000.

[0025] (Polymer layer formation process)

[0026] In the polymer layer formation process, a conductive polymer layer comprising conductive polymers is formed on the surface of the dielectric layer by removing at least a portion of the liquid medium (e.g., water) from the coating solution. The method for removing at least a portion of the liquid medium from the coating solution is not particularly limited. For example, this removal can be carried out by heating and / or reducing pressure, preferably with at least heating. When heating is performed, at least a portion of the liquid medium can be removed by heating at a temperature above 100°C. This allows for rapid removal of water from the liquid medium. The heating temperature is preferably a temperature at which the organic compound neither boils nor decomposes. When the organic compound is a compound that does not exhibit a definite boiling point, heating is preferably performed at a temperature where the evaporation of the organic compound is minimal and the organic compound does not decompose.

[0027] (Polymer layer removal process)

[0028] In the polymer layer removal process, a portion of the conductive polymer layer is removed from a portion of the anode foil, thereby forming an exposed area where that portion of the anode foil is exposed from the conductive polymer layer. When forming the exposed area, a portion of the metal portion and / or the dielectric layer of the anode foil can be removed simultaneously with the removal of the conductive polymer layer. The method for removing a portion of the conductive polymer layer and / or a portion of the anode foil is not particularly limited. For example, removal based on a milling machine, removal based on grinding, removal based on laser irradiation, or removal based on ultrasonic application can be used. Alternatively, by creating an opening in the anode foil, the conductive polymer layer can be removed together with a portion of the anode foil. In this case, the area where the metal portion is exposed on the inner surface of the opening becomes the exposed area. Alternatively, a portion of the conductive polymer layer can also be removed by etching to remove a portion of the anode foil. In the exposed area, it is preferable that the metal portion is exposed from the conductive polymer layer.

[0029] (Lead wire connection process)

[0030] In the lead-connection process, the anode lead is electrically connected to the anode foil by directly contacting the metal portion in the exposed area with the anode lead. The anode lead can be made of metal (e.g., aluminum, aluminum alloy, copper, or copper alloy). The anode lead can also be connected to the anode foil by pin riveting. In pin riveting, a pin is pressed against the anode lead overlapping the anode foil, forming a through hole in the anode foil and the anode lead, thereby allowing a portion of the anode lead to pass through the hole in the anode foil, thus mechanically and electrically connecting the anode foil and the anode lead. In the polymer layer removal process, an exposed area is pre-formed on the anode foil, thereby enabling direct contact between the metal portion and the anode lead in the lead-connection process. Since there is no high-resistivity conductive polymer layer between the metal portion and the anode lead, the connection resistance between the metal portion and the anode lead can be reduced, thus lowering the ESR of the electrolytic capacitor.

[0031] In the polymer layer removal process, a portion of the conductive polymer layer can be removed from both sides of the anode foil. In this case, since exposed areas are formed on both sides of the anode foil, the connection resistance between the anode foil and the anode leads can be further reduced when the anode leads are connected in a manner that contacts both sides of the anode foil. It should be noted that, in the polymer layer removal process, a portion of the conductive polymer layer can also be removed from only one side of the anode foil.

[0032] If the metal part and the anode lead are in direct contact in the exposed area, a conductive polymer layer can be placed between a portion of the anode lead and the anode foil. Even if the entire anode lead is not in contact with the anode foil without a conductive polymer layer, the connection resistance between the anode lead and the anode foil can be sufficiently reduced due to the presence of a portion where the metal part of the anode foil is in direct contact with the anode lead. Furthermore, compared to the case where the entire anode lead is not placed between the anode foil and the anode foil without a conductive polymer layer, the amount of conductive polymer layer removed can be reduced. Therefore, the workload of the removal operation can be reduced. Additionally, since a conductive polymer layer is also formed in the area near the anode lead of the anode foil, the adverse effects caused by areas in the anode foil where no conductive polymer layer is formed (reduction in electrostatic capacitance, increase in ESR) can be suppressed. It should be noted that the entire anode lead may also be placed between the anode foil without a conductive polymer layer. When the area of ​​the region where the anode lead overlaps with the anode foil when viewed from the thickness direction of the anode foil is defined as S1, and the area of ​​the region of the anode foil from which the conductive polymer layer has been removed is defined as S2, the ratio of area S2 to area S1 (S2 / S1) can, for example, be 0.1 or more and 3.0 or less. Furthermore, the ratio (S2 / S1) is preferably 0.5 or more and 1.5 or less, and more preferably 0.9 or more and 1.1 or less. It should be noted that when the ratio (S2 / S1) is less than 1.0, the conductive polymer layer is located between a portion of the anode lead and the anode foil.

[0033] The metal portion can have a core and a porous portion with a lower density than the core. In the polymer layer removal process, in a portion of the anode foil, in addition to removing a portion of the conductive polymer layer, at least a portion of the porous portion can also be removed. The core and the porous portion can be formed, for example, by etching the surface of the metal foil. The porous portion can have multiple micropores extending in the thickness direction of the anode foil, or it can have multiple micropores formed in a sponge-like shape. The porous portion has lower electrical conductivity than the core; therefore, by removing at least a portion of such a porous portion, the anode lead and the core of the metal portion can be made into direct contact, further reducing the connection resistance between them.

[0034] (Electrolytic capacitor)

[0035] The electrolytic capacitor disclosed herein comprises an anode foil, a cathode foil, a separator, a conductive polymer layer, and an anode lead.

[0036] The anode foil has a metal portion and a dielectric layer formed on the surface of the metal portion. Examples of anode foils include metal foils containing at least a portion of valve-acting metals such as titanium, tantalum, aluminum, and niobium, or metal foils containing valve-acting metals (e.g., aluminum foil). The anode foil may contain the valve-acting metal in the form of an alloy or a compound containing the valve-acting metal. The thickness of the anode foil may be 15 μm or more and 300 μm or less. The dielectric layer can be formed by chemically converting the anode foil. In this case, the dielectric layer contains an oxide of the valve-acting metal (e.g., aluminum oxide). It should be noted that the dielectric layer may function as a dielectric or may be composed of a dielectric other than an oxide of the valve-acting metal.

[0037] The cathode foil only needs to function as a cathode and is not particularly limited. Examples of cathode foils include metal foils (e.g., aluminum foil). The type of metal is not particularly limited; it can be a valve-acting metal or an alloy or compound containing a valve-acting metal. The thickness of the cathode foil can be 15 μm or more and 300 μm or less. The surface of the cathode foil can be roughened or chemically converted as needed. The cathode foil may or may not have a conductive polymer layer containing conductive polymers. Examples of conductive polymers can be the same as those described above. The composition of the conductive polymer layer of the cathode foil can be the same as or different from the composition of the conductive polymer layer of the anode foil.

[0038] The cathode foil may include a conductive coating. When the metal foil contains a valve-acting metal, the coating may contain carbon and at least one metal with a lower ionization tendency than the valve-acting metal. This readily improves the acid resistance of the metal foil. When the metal foil contains aluminum, the coating may contain at least one selected from carbon, nickel, titanium, tantalum, and zirconium. From the perspective of cost and low resistance, the coating may contain nickel and / or titanium.

[0039] The thickness of the coating can be 5 nm or more, 10 nm or more, or less than 200 nm. The coating can be formed by vapor deposition or sputtering of the aforementioned metal onto a metal foil. Alternatively, the coating can be formed by vapor deposition of a conductive carbon material onto a metal foil, or by coating a carbon paste containing a conductive carbon material. Examples of conductive carbon materials include graphite, hard carbon, soft carbon, and carbon black.

[0040] A separator lies between the anode foil and the cathode foil. The separator can be a porous sheet material. Examples of porous sheets include woven fabrics, nonwoven fabrics, and microporous membranes. The thickness of the separator is not particularly limited and can be greater than 10 μm and less than 300 μm. Examples of separator materials include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamides, polyimides, polyamide-imides, polyether-imides, rayon, and glass. The separator may or may not have a conductive polymer layer containing conductive polymers. Examples of conductive polymers can be the same as those mentioned above. The composition of the conductive polymer layer of the separator can be the same as or different from the composition of the conductive polymer layer of the anode foil.

[0041] A conductive polymer layer is formed on the surface of the dielectric layer and contains conductive polymers. Examples of conductive polymers are as described above. A portion of the anode foil does not have a conductive polymer layer formed. That is, this portion of the anode foil has an exposed area that exposes from the conductive polymer layer. In the exposed area, preferably, the metal portion is exposed from the conductive polymer layer.

[0042] The anode lead is connected to the anode foil. Specifically, the anode lead is connected to the anode foil through direct contact with the metal portion in the exposed area. This reduces the connection resistance between the metal portion and the anode lead, thereby lowering the ESR of the electrolytic capacitor. The anode lead can be made of metal (e.g., aluminum, aluminum alloy, copper, or copper alloy). The anode lead can also be connected to the anode foil by riveting.

[0043] On both sides of the anode foil, the metal portion can be exposed from the conductive polymer layer. In this case, since exposed areas are formed on both sides of the anode foil, the connection resistance between the anode foil and the anode lead can be further reduced when the anode lead is connected in a manner that contacts both sides of the anode foil. It should be noted that the metal portion may be exposed from the conductive polymer layer only on one side of the anode foil.

[0044] The metal portion may have a core and a porous portion with a lower density than the core. The thickness of the porous portion in a portion of the anode foil may be less than the thickness of the porous portion in the remaining portion of the anode foil. Since the conductivity of the porous portion is lower than that of the core, by making the thickness of such a porous portion smaller, the connection resistance between this portion of the anode foil and the anode lead can be reduced. It should be noted that the case where this portion of the anode foil does not have a porous portion is also included in the configuration described in this paragraph.

[0045] A conductive polymer layer may be disposed between a portion of the anode lead and the anode foil. Even with this configuration, according to the technology disclosed herein, the connection resistance between the anode lead and the anode foil can be sufficiently reduced, thereby reducing the ESR of the electrolytic capacitor.

[0046] As described above, according to this disclosure, in the exposed area formed on a portion of the anode foil, by making the metal portion directly contact the anode lead, the ESR of the electrolytic capacitor can be reduced.

[0047] Hereinafter, an example of an electrolytic capacitor and a method for manufacturing an electrolytic capacitor according to the present disclosure will be specifically described with reference to the accompanying drawings. The constituent elements and processes of the electrolytic capacitor and the method for manufacturing an electrolytic capacitor in the example described below can be applied as described above. The constituent elements and processes of the electrolytic capacitor and the method for manufacturing an electrolytic capacitor in the example described below can be modified based on the above description. Furthermore, the matters described below can also be applied to the above-described embodiments. In the constituent elements and processes of the electrolytic capacitor and the method for manufacturing an electrolytic capacitor in the example described below, constituent elements and processes that are not essential to the electrolytic capacitor and the method for manufacturing an electrolytic capacitor according to the present disclosure can be omitted. It should be noted that the figures shown below are schematic diagrams and do not accurately reflect the actual shape and number of components.

[0048] (Electrolytic capacitor)

[0049] like Figure 1 As shown in Figure 3, the electrolytic capacitor 10 of this embodiment includes: a capacitor element 20, a bottom housing 30 for housing the capacitor element 20, a sealing member 40 for blocking the opening of the bottom housing 30, a base plate 50 covering the sealing member 40, leads 61 and 71 extending from the sealing member 40 and through the base plate, and lead connectors 62 and 72 connecting the leads to the electrodes of the capacitor element 20. The bottom housing 30 is drawn inward near the opening end, and the opening end is rolled to tighten the sealing member 40. One lead 61 and one lead connector 62 constitute the anode lead 60, and another lead 71 and another lead connector 72 constitute the cathode lead 70.

[0050] Capacitor element 20 is, for example, as Figure 2 The wound body shown. The wound body includes: an anode foil 21 connected to the lead connector 62 of the anode lead 60, a cathode foil 22 connected to the lead connector 72 of the cathode lead 70, and a diaphragm 23 between the anode foil 21 and the cathode foil 22. Figure 3A and Figure 3BAs shown, the anode foil 21 includes: a metal portion 21a having a core and a porous portion (neither shown), and a dielectric layer (not shown) formed on the surface of the metal portion 21a. The density of the porous portion is lower than that of the core. A conductive polymer layer 24 containing conductive polymers is formed on the surface of the dielectric layer.

[0051] Electrolytic capacitor 10 may contain a liquid component (e.g., electrolyte) impregnated into capacitor element 20. Examples of liquid components include non-aqueous solvents and electrolytes. The electrolyte may be a mixture of a non-aqueous solvent and an ionic substance (solute, such as an organic salt) dissolved therein. The non-aqueous solvent may be an organic solvent or an ionic liquid. Examples of non-aqueous solvents include polyols such as ethylene glycol and propylene glycol, cyclic sulfones such as sulfolane, lactones such as γ-butyrolactone, amides such as N-methylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone, esters such as methyl acetate, carbonate compounds such as propylene carbonate, ethers such as 1,4-dioxane, ketones such as methyl ethyl ketone, and formaldehyde. Polymer solvents may also be used as non-aqueous solvents. Examples of polymer solvents include polyalkylene glycols, derivatives of polyalkylene glycols, and compounds in which at least one hydroxyl group in a polyol is replaced by a polyalkylene glycol (including derivatives). Specifically, examples of polymeric solvents include polyethylene glycol, polyethylene glycol glycerol ether, polyethylene glycol diglycerol ether, polyethylene glycol sorbitol ether, polypropylene glycol, polypropylene glycol glycerol ether, polypropylene glycol diglycerol ether, polypropylene glycol sorbitol ether, and polybutanediol. Examples of polymeric solvents also include copolymers of ethylene glycol and propylene glycol, copolymers of ethylene glycol and butanediol, and copolymers of propylene glycol and butanediol. Non-aqueous solvents can be used alone or in combination of two or more.

[0052] Examples of organic salts include trimethylamine maleate, triethylamine borosalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazoline phthalate, and mono-1,3-dimethyl-2-ethylimidazoline phthalate. It should be noted that, in this specification, the liquid component can be a component that is liquid at room temperature (25°C) or a component that is liquid at the temperature at which the electrolytic capacitor is used.

[0053] The anode foil 21 and cathode foil 22 are wound together with a diaphragm 23 in between. The outermost periphery of the wound is secured by a winding fixing tape 25. It should be noted that... Figure 2 This indicates the unfolded state of a portion of the fixed winding before its outermost circumference.

[0054] like Figure 3A , Figure 3BAs shown, a portion of the anode foil 21 has exposed regions 21R on both sides where a metal portion 21a (more specifically, the core of the metal portion 21a) is exposed from the conductive polymer layer 24. Furthermore, in this exposed region 21R, the anode lead 60 is mechanically and electrically connected to the anode foil 21 by directly contacting the lead connector 62 of the anode lead 60 with the metal portion 21a. The anode lead 60 is connected to the anode foil 21 by riveting. Therefore, a portion of the lead connector 62 penetrates the metal portion 21a and is in direct contact with both sides of the metal portion 21a.

[0055] In the exposed region 21R, there is almost no porous portion. Therefore, the thickness of the porous portion in the exposed region 21R is smaller than the thickness of the porous portion outside the exposed region 21R of the anode foil 21.

[0056] It should be noted that in this embodiment, there is no conductive polymer layer 24 between the lead connector 62 of the anode lead 60 and the anode foil 21, but there may be a conductive polymer layer 24 between a portion of the anode lead 60 and the anode foil 21.

[0057] (Manufacturing method of electrolytic capacitor)

[0058] Next, a method for manufacturing the electrolytic capacitor 10 of this embodiment will be described. This manufacturing method includes a coating application step, a polymer layer formation step, a polymer layer removal step, and a lead connection step.

[0059] In the coating process, a coating solution comprising a conductive polymer and a liquid medium is applied to the surface of the dielectric layer of the anode foil 21. In this embodiment, the coating solution is applied to the surface of the dielectric layer by a gravure coating method, but it is not limited thereto.

[0060] In the polymer layer formation process, a conductive polymer layer 24 comprising conductive polymers is formed on the surface of the dielectric layer by removing at least a portion of the liquid medium from the coating solution. In this embodiment, this removal is performed by heating under reduced pressure, but is not limited thereto.

[0061] In the polymer layer removal process, a portion of the conductive polymer layer 24 is removed from both sides of a portion of the anode foil 21, thereby forming an exposed region 21R where the portion of the anode foil 21 is exposed from the conductive polymer layer 24. More specifically, in the polymer layer removal process of this embodiment, in addition to removing the portion of the conductive polymer layer 24, the entire porous portion of the metal portion 21a is substantially removed from the portion of the anode foil 21. Here, "substantially removes the entire" means removing 90%, 95%, or 99% or more of the porous portion.

[0062] In the lead connection process, the metal portion 21a (specifically, the core portion of the metal portion 21a) in the exposed area 21R is brought into direct contact with the lead connector 62 of the anode lead 60, and the anode lead 60 is connected to the anode foil 21 by a pin riveting process. In this embodiment, the conductive polymer layer 24 is removed in the polymer layer removal process so that there is no conductive polymer layer 24 between the anode lead 60 and the anode foil 21, but it is also possible that a portion of the anode lead 60 is separated from the anode foil 21 by the conductive polymer layer 24.

[0063] Postscript

[0064] The following technology has been disclosed through the above description of the embodiments.

[0065] (Technology 1)

[0066] An electrolytic capacitor comprising:

[0067] An anode foil having a metal portion and a dielectric layer formed on the surface of the metal portion;

[0068] cathode foil;

[0069] A diaphragm located between the anode foil and the cathode foil;

[0070] A conductive polymer layer formed on the surface of the aforementioned dielectric layer and comprising a conductive polymer; and

[0071] The anode lead connected to the aforementioned anode foil,

[0072] A portion of the aforementioned anode foil has an exposed area that extends beyond the aforementioned conductive polymer layer.

[0073] The anode lead is electrically connected to the anode foil by directly contacting the metal portion in the exposed area.

[0074] (Technology 2)

[0075] According to the electrolytic capacitor described in Technique 1, the metal portion is exposed from the conductive polymer layer on both sides of the anode foil.

[0076] (Technology 3)

[0077] According to the electrolytic capacitor described in Art 1 or 2, the aforementioned metal portion has a core and a porous portion with a lower density than the core.

[0078] The thickness of the porous portion in the aforementioned portion of the anode foil is less than the thickness of the porous portion in the portion other than the aforementioned portion of the anode foil.

[0079] (Technology 4)

[0080] According to any one of the techniques 1 to 3, in an electrolytic capacitor, the conductive polymer layer is located between a portion of the anode lead and the anode foil.

[0081] (Technology 5)

[0082] A method for manufacturing an electrolytic capacitor, wherein the electrolytic capacitor comprises an anode foil having a metal portion and a dielectric layer formed on the surface of the metal portion, a cathode foil, and a separator.

[0083] The method for manufacturing the electrolytic capacitor includes:

[0084] The coating process involves applying a coating solution comprising a conductive polymer and a liquid medium to the surface of the dielectric layer of the anode foil.

[0085] The polymer layer forming process involves removing at least a portion of the liquid medium from the coating liquid, thereby forming a conductive polymer layer containing the conductive polymer on the surface of the dielectric layer.

[0086] The polymer layer removal process involves removing a portion of the conductive polymer layer from a portion of the anode foil to form an exposed area where the portion of the anode foil is exposed from the conductive polymer layer; and

[0087] The lead connection process involves electrically connecting the anode lead to the anode foil by bringing the metal portion in the exposed area into direct contact with the anode lead.

[0088] (Technology 6)

[0089] According to the manufacturing method of the electrolytic capacitor described in Technique 5, in the polymer layer removal process, a portion of the conductive polymer layer is removed from both sides of the anode foil.

[0090] (Technology 7)

[0091] According to the manufacturing method of the electrolytic capacitor described in Technique 5 or 6, the conductive polymer layer is disposed between a portion of the anode lead and the anode foil.

[0092] (Technology 8)

[0093] According to any one of the methods for manufacturing an electrolytic capacitor described in art 5 to 7, the aforementioned metal portion has a core and a porous portion with a lower density than the core.

[0094] In the polymer layer removal process described above, in the aforementioned portion of the anode foil, in addition to removing the aforementioned portion of the conductive polymer layer, at least a portion of the porous portion is also removed.

[0095] Example

[0096] For the anode foils (hereinafter also referred to as leaded anode foils) with anode leads connected to them in the embodiments, comparative examples, and reference examples 1 and 2 shown below, the connection resistance between the anode foil and the anode leads was measured, and the ESR of the electrolytic capacitors made using each anode foil was measured.

[0097] Example

[0098] An aluminum foil (100 μm thick) is etched to roughen its surface. The roughened surface is then chemically converted to form a dielectric layer. This yields an anode foil with dielectric layers on both sides.

[0099] A commercially available dispersion (prepared by dispersing polyvinyl sulfonic acid (PSS)-doped polyethylene dioxythiophene (PEDOT) particles in water was prepared. Ethylene glycol and water were added to this dispersion to obtain a coating solution.

[0100] Using a gravure coating machine, a coating solution is applied to one side of the anode foil (the surface of the dielectric layer). Then, a drying process is performed, forming a conductive polymer layer on one side of the anode foil (the surface of the dielectric layer). Next, a conductive polymer layer is formed on the other side of the anode foil (the surface of the dielectric layer) using the same method.

[0101] By forming a hole in an anode foil on which a conductive polymer layer has been formed, a portion of the conductive polymer layer and a portion of the anode foil (specifically, the dielectric layer and the porous portion) are removed from a portion of the anode foil, and an exposed area of ​​the core of the metal portion is formed on the inner surface of the hole.

[0102] By placing the lead connector of the anode lead in the exposed area and using a pin-riveting process to make the lead connector directly contact the core of the metal part of the anode foil, the anode lead is electrically connected to the anode foil.

[0103] After obtaining the leaded anode foil in this way, the connection resistance between the anode lead and the anode foil is measured using a four-terminal measurement method. In this embodiment, the connection resistance was measured to be 0.55 mΩ.

[0104] Additionally, an electrolytic capacitor was fabricated using the leaded anode foil from the embodiment. This electrolytic capacitor has an ESR of 9.62 mΩ. It should be noted that the ESR was measured using an LCR meter at a frequency of 100 kHz / Ω.

[0105] Comparative Examples

[0106] Except for omitting the punching process in the anode foil where a conductive polymer layer is formed, the leaded anode foil was fabricated using the same process as in the embodiment. The connection resistance between the anode lead and the anode foil in the comparative example's leaded anode foil was 2.07 mΩ. Furthermore, the ESR of the electrolytic capacitor fabricated using the comparative example's leaded anode foil was 11.31 mΩ.

[0107] Reference Example 1

[0108] Except for the step of not forming a conductive polymer layer on the surface of the dielectric layer, the leaded anode foil was fabricated using the same process as in the example. The connection resistance between the anode lead and the anode foil in the leaded anode foil of Reference Example 1 was 0.52 mΩ. Furthermore, the ESR of the electrolytic capacitor fabricated using the leaded anode foil of Reference Example 1 was 200.5 mΩ.

[0109] Reference Example 2

[0110] Except for the omission of the process of forming a conductive polymer layer on the surface of the dielectric layer and the omission of the punching process, the leaded anode foil was fabricated using the same process as in the embodiment. The connection resistance between the anode lead and the anode foil in the leaded anode foil of Reference Example 2 was 0.57 mΩ. Furthermore, the ESR of the electrolytic capacitor fabricated using the leaded anode foil of Reference Example 1 was 208.3 mΩ.

[0111] As described above, the connection resistance between the anode lead and the anode foil in the embodiment is significantly lower than that in the comparative example. Furthermore, correspondingly, the ESR of the electrolytic capacitor in the embodiment is also significantly lower than that of the electrolytic capacitor in the comparative example. Therefore, it can be said that the embodiment demonstrates superiority.

[0112] Industrial availability

[0113] This disclosure can be used for electrolytic capacitors and methods for manufacturing electrolytic capacitors.

[0114] Explanation of reference numerals in the attached figures

[0115] 10: Electrolytic capacitors

[0116] 20: Capacitor Components

[0117] 21: Anode foil

[0118] 21a: Metal section

[0119] 21R: Exposed Area

[0120] 22: Cathode foil

[0121] 23: Diaphragm

[0122] 24: Conductive polymer layer

[0123] 25: Winding and fixing tape

[0124] 30: With a bottom shell

[0125] 40: Sealing components

[0126] 50: Seat plate

[0127] 60: Anode lead

[0128] 61: Lead wire

[0129] 62: Lead wire connector

[0130] 70: Cathode lead

[0131] 71: Lead wire

[0132] 72: Lead wire connector

Claims

1. An electrolytic capacitor comprising: An anode foil having a metal portion and a dielectric layer formed on the surface of the metal portion; cathode foil; A membrane located between the anode foil and the cathode foil; A conductive polymer layer formed on the surface of the dielectric layer and comprising conductive polymers; as well as The anode lead connected to the anode foil, A portion of the anode foil has an exposed area that protrudes from the conductive polymer layer. The anode lead is electrically connected to the anode foil by direct contact with the metal portion in the exposed area.

2. The electrolytic capacitor according to claim 1, wherein, On both sides of the anode foil, the metal portion is exposed from the conductive polymer layer.

3. The electrolytic capacitor according to claim 1 or 2, wherein, The metal portion has a core and a porous portion with a lower density than the core. The thickness of the porous portion in the portion of the anode foil is less than the thickness of the porous portion in the portion of the anode foil outside the portion.

4. The electrolytic capacitor according to claim 1 or 2, wherein, The conductive polymer layer is located between a portion of the anode lead and the anode foil.

5. A method for manufacturing an electrolytic capacitor, wherein, The electrolytic capacitor comprises an anode foil, a cathode foil, and a separator, each having a metal portion and a dielectric layer formed on the surface of the metal portion. The method for manufacturing the electrolytic capacitor includes: The coating process involves applying a coating solution comprising a conductive polymer and a liquid medium to the surface of the dielectric layer of the anode foil. The polymer layer forming process involves removing at least a portion of the liquid medium from the coating liquid, thereby forming a conductive polymer layer containing the conductive polymer on the surface of the dielectric layer. The polymer layer removal process forms an exposed area of ​​the anode foil from the conductive polymer layer by removing a portion of the conductive polymer layer from a portion of the anode foil. as well as The lead connection process electrically connects the anode lead to the anode foil by bringing the metal portion in the exposed area into direct contact with the anode lead.

6. The method for manufacturing an electrolytic capacitor according to claim 5, wherein, In the polymer layer removal process, a portion of the conductive polymer layer is removed from both sides of the anode foil.

7. The method for manufacturing an electrolytic capacitor according to claim 5 or 6, wherein, The conductive polymer layer is located between a portion of the anode lead and the anode foil.

8. The method for manufacturing an electrolytic capacitor according to claim 5 or 6, wherein, The metal portion has a core and a porous portion with a lower density than the core. In the polymer layer removal process, in the portion of the anode foil, in addition to removing the portion of the conductive polymer layer, at least a portion of the porous portion is also removed.

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