Capacitor element and electrolytic capacitor, and method for manufacturing the same

Abstract

A capacitor element comprises: an anode body having a porous region on a surface, a dielectric layer covering at least a portion of the anode body, and a cathode layer covering at least a portion of the dielectric layer, wherein the anode body comprises: an anode portion, and a cathode forming portion adjacent to the anode portion and having the cathode layer formed thereon, a thin-walled region thinner than the porous region in the cathode forming portion is formed in at least a portion of the porous region of the anode portion, and a metal substrate is stacked on at least a portion of the thin-walled region, the metal substrate being denser than the porous region in the cathode forming portion.

Description

Technical Field

[0001] The present invention relates to a capacitor element and an electrolytic capacitor, and methods for manufacturing the same. Background Art

[0002] Electrolytic capacitors are used in various electronic devices because of their low equivalent series resistance (ESR) and excellent frequency characteristics. The capacitor element used in the electrolytic capacitor includes a foil as an anode body, and the foil includes a valve metal such as titanium, tantalum, aluminum, and niobium. The anode body is generally divided into an anode portion and a cathode forming portion. A cathode layer including a solid electrolyte layer and a cathode lead layer is formed on the surface of the anode body in the cathode forming portion.

[0003] As electronic devices become more functional, electrolytic capacitors with high capacitance are required. Therefore, it is proposed to stack a plurality of capacitor elements and arrange them in an electrolytic capacitor. The anode parts of the capacitor elements are joined to each other by welding, for example (Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-088073 Summary of the invention

[0007] The ESR of an electrolytic capacitor including stacked capacitor elements tends to increase.

[0008] A first aspect of the present invention relates to a capacitor element, comprising: an anode body having a porous region on a surface, a dielectric layer covering at least a portion of the anode body, and a cathode layer covering at least a portion of the dielectric layer, the anode body having: an anode portion, and a cathode forming portion adjacent to the anode portion and having the cathode layer formed thereon, a thin-walled region thinner than the porous region in the cathode forming portion being formed in at least a portion of the porous region of the anode portion, a metal substrate being stacked on at least a portion of the thin-walled region, the metal substrate being denser than the porous region in the cathode forming portion.

[0009] A second aspect of the present invention relates to an electrolytic capacitor including a plurality of stacked capacitor elements.

[0010] A third aspect of the present invention relates to a method for manufacturing a capacitor element, comprising: a preparation step of preparing an anode body having a porous area on the surface; a dielectric layer forming step of forming a dielectric layer covering at least a portion of the anode body; a thin-walled area forming step of compressing or removing a portion of the porous area to form a thin-walled area on the anode body; a stacking step of stacking a metal substrate on at least a portion of the thin-walled area; and a cathode forming step of forming a cathode layer in a cathode forming portion in a portion of the anode body other than the thin-walled area, the stacked metal substrate being denser than the porous area in the cathode forming portion.

[0011] A fourth aspect of the present invention relates to a method for manufacturing an electrolytic capacitor, comprising: a step of preparing a capacitor element manufactured by the above method; and a step of laminating a plurality of the capacitor elements and welding the thin-walled regions together with the metal substrate.

[0012] An electrolytic capacitor with reduced ESR can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A It is a top view schematically showing a capacitor element according to one embodiment of the present invention.

[0014] Figure 1B To schematically illustrate the Figure 1A A cross-sectional view of a capacitor element cut along line XX.

[0015] Figure 2 It is a top view schematically showing a capacitor element according to another embodiment of the present invention.

[0016] Figure 3A It is a top view schematically showing a capacitor element according to still another embodiment of the present invention.

[0017] Figure 3B To schematically illustrate the Figure 3A A cross-sectional view of a main portion of a capacitor element cut along line YY.

[0018] Figure 4A It is a top view schematically showing a capacitor element according to still another embodiment of the present invention.

[0019] Figure 4B To schematically illustrate the Figure 4A A cross-sectional view of a main portion of a capacitor element cut along line ZZ.

[0020] Figure 5 This is a cross-sectional view schematically showing an electrolytic capacitor according to one embodiment of the present invention.

[0021] Figure 6 This is a flowchart showing a method for manufacturing a capacitor element according to one embodiment of the present invention.

[0022] Figure 7 This is a flowchart showing a method for manufacturing a capacitor element according to another embodiment of the present invention.

[0023] Figure 8 This is a flowchart showing a method for manufacturing an electrolytic capacitor according to one embodiment of the present invention. DETAILED DESCRIPTION

[0024] [Capacitor elements]

[0025] In order to increase the electrostatic capacitance, a porous region is usually formed on the surface of the anode body. If the anode portions of the stacked multiple capacitor elements are welded to each other, a larger void is sometimes formed in the porous region. Therefore, the resistance of the anode portion becomes larger, so that the ESR is easily increased. Furthermore, there is also a situation where the strength of the capacitor element in the welded portion is reduced. In addition, the oxygen intruding from the anode portion easily reaches the cathode forming portion through the gap, so that the degradation of the solid electrolyte layer proceeds.

[0026] Therefore, in the capacitor element involved in this embodiment, the porous area in the anode portion is thinned to form a thin-walled area, and a dense metal substrate is stacked in a part thereof. By welding the capacitor elements to each other in the stacked portion, the occupancy ratio of the void in the welded portion becomes smaller, or the void itself becomes smaller. Therefore, the increase in resistance is suppressed, and the movement of oxygen is also suppressed. Furthermore, the thin-walled area is strengthened by the metal substrate, so that the strength of the capacitor element is improved.

[0027] A cathode layer (e.g., a solid electrolyte layer and a cathode lead-out layer) is formed in the cathode forming portion of the anode body. Therefore, the thickness of the cathode forming portion of the capacitor element is greater than that of the anode portion. When a plurality of capacitor elements are stacked and the anode portions are joined to each other, the anode body is bent near the boundary between the anode portion and the cathode layer. Therefore, the anode body is easily damaged in the bent portion. If a thin-walled region is provided in the anode portion, the degree of the bending is further increased. In the present embodiment, since a metal substrate is stacked in at least a portion of the thin-walled region, a plurality of capacitor elements can be stacked and joined without increasing the degree of bending.

[0028] The thicker the porous region is, the lower the strength of the capacitor element is. However, in the present embodiment, since the thin-walled region is reinforced by the metal substrate, the porous region can be thickened. That is, the porous region in the cathode forming portion can be thickened. Therefore, an increase in electrostatic capacitance can be expected. In the cathode forming portion, the thickness of the porous region can be more than 95% of the thickness of the entire anode body. From the perspective of strength, the thickness of the porous region in the cathode forming portion is preferably less than 98% of the thickness of the entire anode body.

[0029] The thin-walled region only needs to be formed in a part of the anode portion. From the viewpoint of oxygen barrier, the thin-walled region is preferably formed in a strip shape along the direction of the boundary between the anode portion and the cathode forming portion. The thin-walled region is more preferably formed in a strip shape near the boundary between the anode portion and the cathode forming portion. This is because, by using the thin-walled region, it is easy to suppress the solid electrolyte from penetrating to the anode side in the formation process of the solid electrolyte layer. The thin-walled region can be formed in the entire anode portion.

[0030] The thin-walled region can be formed by removing a portion of the porous region or by compressing a portion of the porous region. Preferably, the thin-walled region is formed by compressing the porous region. By compressing the porous region, a compressed layer with a smaller porosity is formed in the thin-walled region, thereby further improving the effect of suppressing resistance and the effect of suppressing oxygen migration.

[0031] The metal substrate is laminated on at least a portion of the thin-walled region. The portion laminated with the metal substrate is suitable as a welding portion. From the viewpoint of oxygen barrier, the metal substrate is preferably laminated in a strip shape along the direction of the boundary between the anode portion and the cathode forming portion. From the viewpoint of strength, the metal substrate is preferably laminated on the entire thin-walled region.

[0032] Hereinafter, the capacitor element according to the present embodiment will be described in detail with reference to the drawings. However, the present embodiment is not limited thereto.

[0033] [First embodiment]

[0034] The capacitor element involved in this embodiment has an island-shaped thin-walled area in the welding predetermined part of the anode part. The area of ​​the thin-walled area is, for example, more than 3% and less than 10% of the area of ​​the anode part. The metal substrate is stacked on the entire thin-walled area. As a result, the increase in resistance caused by welding is suppressed. Furthermore, it is also easy to suppress the movement of oxygen.

[0035] Figure 1A It is a top view schematically showing the capacitor element according to the present embodiment. Figure 1B To schematically illustrate the Figure 1A A cross-sectional view of a capacitor element cut along line XX.

[0036] The capacitor element 110 is, for example, in a sheet shape. The capacitor element 110 includes an anode body 11, a dielectric layer 12 covering at least a portion of the anode body 11, and a cathode layer 13 covering at least a portion of the dielectric layer. The cathode layer 13 includes a solid electrolyte layer 131 and a cathode extraction layer 132 covering at least a portion of the solid electrolyte layer 131.

[0037] The anode body 11 includes an anode portion 11a and a cathode forming portion 11b. Porous regions 11X are arranged on both main surface sides of the anode body 11. A core region 11Y is sandwiched between the two porous regions 11X. The thickness of the core region 11Y is sometimes larger than Figure 1B The one shown is smaller.

[0038] Two island-shaped thin-walled regions are formed in a part of the anode portion 11a. The thickness of the porous region 11X in the thin-walled region is thinner than that of the porous region 11X in the cathode forming portion 11b. The metal substrate 20 is stacked in the entire thin-walled region. In the thin-walled region, a plurality of capacitor elements 110 are welded.

[0039] [Second embodiment]

[0040] The capacitor element involved in this embodiment has: a thin-walled area arranged at the end of the anode portion and formed in a strip shape along the direction of the boundary between the anode portion and the cathode forming portion. The area of ​​the thin-walled area is, for example, more than 10% and less than 50% of the area of ​​the anode portion. The metal substrate is stacked on the entire thin-walled area. As a result, the increase in resistance caused by welding is suppressed. Furthermore, it is also easy to suppress the movement of oxygen. In addition, the strength of the capacitor element is improved.

[0041] Figure 2 It is a top view schematically showing the capacitor element according to the present embodiment.

[0042] The present embodiment has the same configuration as the first embodiment except that a strip-shaped thin-walled region is formed at the end of the anode portion 11a. The metal substrate 20 is laminated on the entire thin-walled region. The capacitor element according to the present embodiment has Figure 1B Same cross section.

[0043] [Third Embodiment]

[0044] The capacitor element involved in this embodiment has: a thin-walled area arranged at the end of the anode portion and formed in a strip shape in the direction along the boundary between the anode portion and the cathode forming portion. The thin-walled area of ​​this embodiment is wider than the thin-walled area of ​​the second embodiment. Therefore, when multiple capacitor elements are stacked, the capacitor element is bent in the portion containing the thin-walled area. The area of ​​the thin-walled area is, for example, more than 50% and less than 80% of the area of ​​the anode portion. The metal substrate is stacked on the entire thin-walled area. As a result, the increase in resistance caused by welding is suppressed. Furthermore, it is also easy to suppress the movement of oxygen. In addition, the strength of the capacitor element is further improved.

[0045] Figure 3A It is a top view schematically showing the capacitor element according to the present embodiment. Figure 3B To schematically illustrate the Figure 3A A cross-sectional view of a capacitor element cut along line YY.

[0046] This embodiment has the same configuration as the first embodiment except that a band-shaped thin-walled region is formed in a part including the end of the anode portion 11 a . The metal substrate 20 is laminated on the entire thin-walled region.

[0047] [Fourth embodiment]

[0048] The capacitor element involved in this embodiment has a thin-walled area in the entire anode portion. The thin-walled area is formed in the entire anode portion. The metal substrate is stacked on the entire thin-walled area. As a result, the increase in resistance caused by welding is suppressed. In addition, the movement of oxygen is further suppressed. In addition, the strength of the capacitor element is improved, and it is also easy to suppress the penetration of the solid electrolyte to the anode side.

[0049] Figure 4A It is a top view schematically showing the capacitor element according to the present embodiment. Figure 4B To schematically illustrate the Figure 4A A cross-sectional view of a capacitor element cut along line ZZ.

[0050] This embodiment has the same configuration as that of the first embodiment except that the thin-walled region is formed over the entire anode portion 11 a . The metal substrate 20 is laminated over the entire thin-walled region.

[0051] (Thin-walled area)

[0052] The thin-walled region is formed in at least a portion of the anode portion. The porous region in the thin-walled region is thinner than the porous region in the cathode forming portion. Therefore, it is difficult for oxygen intruding from the anode portion to pass through the thin-walled region and reach the cathode forming portion. The thin-walled region further has the function of preventing the solid electrolyte from penetrating to the anode side via the porous region of the cathode forming portion during the formation process of the solid electrolyte layer.

[0053] The thickness of the porous region in the thin-walled region is not particularly limited. The thickness of the porous region in the thin-walled region is preferably 50% or less, preferably 40% or less, and preferably 30% or less of the thickness of the porous region in the cathode forming portion. The porous region may not exist in the thin-walled region.

[0054] The thickness of the porous region in the thin-walled region is the average value of the distances from one main surface of the anode body in the thin-walled region to any three points of the boundary between the porous region and the core region formed on the main surface side in the cross section of the capacitor element. The thickness of the porous region in the cathode forming portion is similarly the average value of the distances from one main surface of the anode body in the cathode forming portion to any three points of the boundary between the porous region and the core region formed on the main surface side.

[0055] The thin-walled region is formed, for example, by compressing the porous region of the anode body. In this case, the thin-walled region has a compression layer formed by compressing the porous region. The thin-walled region can be formed by removing at least a portion of the porous region by cutting or laser processing. The thin-walled region can also be formed by removing all of the porous region to expose the core region. Among them, the thin-walled region is preferably formed by compressing the porous region of the anode body. This is because the process is simple and further improvement of the oxygen barrier property can be expected.

[0056] (Metal substrate)

[0057] The metal substrate is laminated on at least a portion of the thin-walled region. The metal substrate is denser than the porous region in the cathode forming portion. By configuring a dense metal substrate instead of the porous region, the increase in resistance of the anode portion caused by welding is suppressed, and the oxygen barrier property is improved. Furthermore, the strength reduction of the capacitor element caused by the formation of the thin-walled region can be avoided.

[0058] The metal substrate is denser than the porous region in the cathode forming part, which means that the apparent density of the metal substrate is greater than the apparent density of the porous region in the cathode forming part. The apparent density is calculated by dividing the actual mass by the apparent volume including the voids.

[0059] The so-called dense metal substrate also has the same meaning as the following: the porosity of the metal substrate is smaller than the porosity of the porous region in the cathode forming portion. The porosity of the metal substrate is, for example, 90% or less of the porosity of the porous region in the cathode forming portion, and may be 80% or less, or 60% or less. The metal substrate may not have pores therein. The porosity of the metal substrate is not particularly limited. The porosity of the metal substrate may be, for example, 0% or more and 55% or less.

[0060] The porosity can be calculated from the SEM image of the cross section obtained by cutting the capacitor element in the thickness direction. The portion corresponding to the porous region in the cathode forming portion of the above SEM image is binarized in the void portion and other portions, and the area ratio of the void portion in the above porous region is calculated. The obtained area ratio of the void portion is used as the porosity of the porous region in the cathode forming portion. Similarly, the area ratio of the void portion in the metal substrate is calculated from the SEM image, and the obtained area ratio of the void portion is used as the porosity of the metal substrate.

[0061] The metal substrate is a plate-shaped or foil-shaped member containing a metal material. The thickness of the metal substrate is not particularly limited. The total thickness of the metal substrate and the anode body in the thin-walled area may be smaller than the thickness of the anode body in the cathode forming portion, may be larger than the thickness of the anode body in the cathode forming portion, or may be the same as the thickness of the anode body in the cathode forming portion. Among them, from the perspective of easy welding of multiple capacitor elements, the above-mentioned total thickness is preferably greater than the thickness of the anode body in the cathode forming portion. The above-mentioned total thickness is preferably greater than 100% and less than 120% of the thickness of the anode body in the cathode forming portion.

[0062] The metal material constituting the metal substrate is not particularly limited. The metal substrate preferably comprises the same metal material as the anode body or a valve metal. In this case, the resistance between the anode body and the metal substrate, the ease of welding, etc. are the same, so it is not easy to damage the connection reliability.

[0063] The surface of the stacked metal substrate opposite to the thin-walled area (hereinafter sometimes referred to as the opposite surface) is preferably roughened. This is because the adhesion with the porous area will be improved. The roughness of the opposite surface is not particularly limited. The arithmetic mean roughness Ra of the opposite surface can be, for example, 20 nm or more. The arithmetic mean roughness Ra is measured in accordance with JIS B 0601:2013. The metal substrate can have a porous area on the surface like the anode body. The surface of the metal substrate on the opposite side of the opposite surface can also be roughened in the same manner. Thus, when multiple capacitor elements are stacked, the adhesion with the adjacent anode portion is easily improved.

[0064] The method of roughening is not particularly limited. The opposing surface may be etched or roughened by conventionally known surface treatment such as plasma treatment or sandblasting.

[0065] (Anode)

[0066] The anode body has a foil (metal foil) containing a valve metal. Examples of the valve metal include titanium, tantalum, aluminum, and niobium. The anode body contains one or more of the above-mentioned valve metals. The anode body may contain the above-mentioned valve metal in the form of an alloy or an intermetallic compound. The thickness of the anode body is not particularly limited. The thickness of the anode body excluding the thin-walled area is, for example, greater than 15 μm and less than 300 μm, and may be greater than 80 μm and less than 250 μm.

[0067] The main surface of the anode body can be roughened by electrolytic etching or the like. Therefore, the anode body has a porous region formed on its main surface side. The anode body as a whole can be porous. Among them, from the viewpoint of strength, the anode body preferably has a porous region arranged on the two main surface sides, and a core region sandwiched between the porous regions and having a lower porosity than the porous region. The porous region is a region having a plurality of fine holes. The core region is, for example, a region that is not electrolytically etched. The porous region and the core region can be distinguished according to the cross section of the capacitor element.

[0068] The porosity of the porous region is not particularly limited, and the porosity of the porous region may be, for example, 35% or more and 65% or less.

[0069] The thickness of the porous region is not particularly limited. As described above, from the viewpoint of electrostatic capacitance and strength, the thickness of the porous region in the cathode forming portion is preferably 95% to 98% of the thickness of the entire anode body.

[0070] (Dielectric layer)

[0071] The dielectric layer is formed on at least a portion of the surface of the anode body. The dielectric layer is formed, for example, by anodizing the surface of the anode body using a chemical conversion treatment or the like. Therefore, the dielectric layer may contain an oxide of a valve metal. For example, when aluminum is used as the valve metal, the dielectric layer may contain Al2O3. It should be noted that the dielectric layer is not limited thereto, as long as it functions as a dielectric.

[0072] (Cathode layer)

[0073] The cathode layer includes a solid electrolyte layer covering at least a portion of the dielectric layer, and a cathode lead layer covering at least a portion of the solid electrolyte layer.

[0074] The solid electrolyte layer may be formed so as to cover at least a portion of the dielectric layer, or may be formed so as to cover the entire surface of the dielectric layer.

[0075] The solid electrolyte layer includes, for example, a manganese compound and a conductive polymer. As the conductive polymer, polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polythiophene vinylene, etc. can be cited. They can be used alone, in combination of two or more, or as a copolymer of two or more monomers.

[0076] It should be noted that in this specification, polypyrrole, polythiophene, polyfuran, polyaniline, etc. refer to polymers with polypyrrole, polythiophene, polyfuran, polyaniline, etc. as basic skeletons, respectively. Therefore, polypyrrole, polythiophene, polyfuran, polyaniline, etc. may also include their respective derivatives. For example, polythiophene includes poly(3,4-ethylenedioxythiophene) and the like.

[0077] Conductive polymers can be included in the solid electrolyte layer together with dopants. Dopants can be monomolecular anions or polymer anions. As specific examples of monomolecular anions, p-toluenesulfonic acid, naphthalenesulfonic acid, etc. can be cited. As specific examples of polymer anions, polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic acid sulfonic acid, polymethacrylic acid sulfonic acid, poly (2-acrylamide-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, etc. can be cited. They can be used alone or in combination of two or more. In addition, it can be a polymer of these single monomers or a copolymer of two or more monomers. Among them, polymer anions derived from polystyrene sulfonic acid are preferred.

[0078] The cathode lead layer may be formed so as to cover at least a portion of the solid electrolyte layer, and may be formed so as to cover the entire surface of the solid electrolyte layer.

[0079] The cathode lead layer comprises, for example, a carbon layer and a metal (e.g., silver) paste layer formed on the surface of the carbon layer. The carbon layer is composed of a carbon paste containing a conductive carbon material such as graphite. The metal paste layer is composed of, for example, a composition containing silver particles and a resin. It should be noted that the composition of the cathode lead layer is not limited thereto, as long as it has a current collection function.

[0080] [Electrolytic capacitors]

[0081] The electrolytic capacitor according to the present embodiment includes the above-mentioned capacitor element.

[0082] The electrolytic capacitor may include a plurality of capacitor elements. The plurality of capacitor elements are stacked. The number of stacked capacitor elements is not particularly limited, and is, for example, 2 or more and 20 or less.

[0083] It is sufficient that at least one of the plurality of capacitor elements is the capacitor element according to the present embodiment. The others may be conventionally known capacitor elements. It is preferred that all of the plurality of capacitor elements arranged in the electrolytic capacitor are the capacitor elements according to the present embodiment.

[0084] The anode parts of the stacked capacitor elements are joined to each other by welding to be electrically connected. According to this embodiment, the stacked capacitor elements are welded at the portion where the metal substrate is stacked, so that the occupancy ratio of the gap formed by welding becomes smaller, or the gap itself becomes smaller. Therefore, the increase in the resistance of the anode part is suppressed. For example, a plurality of anode parts can be welded after riveting using a bent anode lead terminal.

[0085] The anode lead terminal is bonded to the anode portion of at least one capacitor element. In this case, the anode lead terminal and the portion of the anode portion where the metal substrate is laminated may be welded.

[0086] In addition, the cathode layers of the stacked capacitor elements are also electrically connected to each other. The cathode lead terminal is bonded to the cathode layer of at least one capacitor element. The cathode lead terminal is bonded using a conductive adhesive, solder, or by resistance welding or laser welding. The conductive adhesive is, for example, a mixture of a curable resin and carbon particles or metal particles.

[0087] (Lead terminal)

[0088] The material of the lead terminal is not particularly limited as long as it is electrochemically stable and chemically stable and has conductivity, and may be metal or non-metal. Its shape is also not particularly limited. From the perspective of reducing the height (Japanese: low-profile), the thickness of the lead terminal (the distance between the main surfaces of the lead terminal) is preferably 25 μm or more and 200 μm or less, and more preferably 25 μm or more and 100 μm or less.

[0089] (Sealing resin)

[0090] The capacitor element may be sealed with a sealing resin so that at least a portion of the anode lead terminal and the cathode lead terminal are exposed.

[0091] As the sealing resin, for example, a cured product of a curable resin and engineering plastics can be cited. As the curable resin, for example, epoxy resin, phenolic resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane, and unsaturated polyester can be cited. Engineering plastics include general engineering plastics and super engineering plastics. As engineering plastics, for example, polyimide and polyamide-imide can be cited.

[0092] Figure 5The cross-sectional view schematically shows an electrolytic capacitor according to the present embodiment. The electrolytic capacitor 100 includes one or more capacitor elements 110 , an anode lead terminal 120A bonded to the anode portion 11 a , a cathode lead terminal 120B bonded to the cathode layer 13 , and a sealing resin 130 sealing the capacitor element 110 .

[0093] [Capacitor element manufacturing method]

[0094] The capacitor element according to the present embodiment can be manufactured by the following method. The present embodiment includes a method for manufacturing a capacitor element.

[0095] The manufacturing method of the capacitor element according to the present embodiment comprises: a preparation step of preparing an anode body having a porous region on the surface; a dielectric layer forming step of forming a dielectric layer covering at least a portion of the anode body; a thin-wall region forming step of compressing or removing a portion of the porous region to form a thin-wall region on the anode body; a lamination step of laminating a metal substrate on at least a portion of the thin-wall region; and a cathode forming step of forming a cathode layer on a portion of the anode body other than the thin-wall region. The laminated metal substrate is denser than the porous region in the cathode forming portion.

[0096] Figure 6 This is a flowchart showing the method for manufacturing the capacitor element according to the present embodiment. Figure 7 This is a flowchart showing another method of manufacturing a capacitor element according to the present embodiment.

[0097] (1) Preparation process (S11)

[0098] As a raw material of the anode body, for example, a metal foil containing a valve action metal is used.

[0099] At least one main surface of the metal foil is roughened. By roughening, a porous region having a plurality of fine pores is formed on at least the main surface of the metal foil.

[0100] Roughening is performed, for example, by electrolytic etching of the metal foil. Electrolytic etching can be performed, for example, by direct current electrolysis or alternating current electrolysis. Etching conditions are not particularly limited and are appropriately set according to the depth of the porous region, the type of valve metal, and the like.

[0101] (2) Dielectric layer forming step (S12)

[0102] A dielectric layer is formed on the surface of the anode body. The method for forming the dielectric layer is not particularly limited. The dielectric layer can be formed, for example, by subjecting the anode body to a chemical conversion treatment. In the chemical conversion treatment, for example, the anode body is immersed in a chemical conversion liquid such as an ammonium adipate solution and heat-treated. Alternatively, the anode body can be immersed in a chemical conversion liquid and a voltage can be applied.

[0103] (3) Thin-walled region forming step (S13)

[0104] The porous region of the anode body is partially compressed or removed to form a thin-walled region with a small thickness in a portion of the anode body. The remaining portion of the anode body that is not compressed or removed includes a cathode forming portion where a cathode layer is to be formed.

[0105] The compression of the porous region can be performed by pressing the anode part. The removal of the porous region can be performed by cutting the porous region of the anode part.

[0106] (4) Lamination step (S14)

[0107] The metal substrate is laminated on at least a portion of the thin-walled area. After lamination, the laminated portion of the metal substrate and the anode body can be pressed so that the metal substrate and the anode body are in close contact. In this case, as the metal substrate, a metal foil having the same porosity as the anode body can also be used. By pressing after lamination, the porous area of ​​the metal substrate is compressed, thereby densifying the metal substrate. The laminated metal substrate can be etched in the same manner as the anode body. The surface of the laminated metal substrate can also be roughened.

[0108] From the viewpoint of ensuring strength, the lamination step (4) is preferably performed after the thin-walled region forming step (3), or in parallel with the thin-walled region forming step (3). Among them, it is preferred that the thin-walled region forming step (3) and the lamination step (4) are performed in parallel (see Figure 7 ).

[0109] Specifically, the metal substrate is arranged in a manner covering a part of the porous region, and the stacked portion of the metal substrate and the anode body is pressed. As a result, the porous region is compressed to form a thin-walled region, and the metal substrate is stacked on the thin-walled region. At the same time, the metal substrate and the anode body are crimped. According to this method, the working hours can be reduced, and further, it is easy to arrange the metal substrate in the thin-walled region.

[0110] (5) Cathode Forming Step (S15)

[0111] A solid electrolyte layer is formed on the surface of the dielectric layer.

[0112] The solid electrolyte layer can be formed by chemically polymerizing and / or electrolytically polymerizing raw material monomers or oligomers in the presence of an anode body. The solid electrolyte layer can be formed by applying a solution in which a conductive polymer is dissolved or a dispersion in which a conductive polymer is dispersed to the dielectric layer.

[0113] The raw material monomer or oligomer is a monomer or oligomer used as a raw material of the above-mentioned conductive polymer, for example, pyrrole, aniline, thiophene, their derivatives, etc. The polymerization solution used in the chemical polymerization and / or electrolytic polymerization may contain the above-mentioned dopant in addition to the raw material monomer or oligomer.

[0114] Next, a carbon paste and a silver paste are sequentially applied on the surface of the solid electrolyte layer to form a cathode lead layer. In this way, a cathode layer is formed to obtain a capacitor element.

[0115] It should be noted that the thin-walled region forming step (3) and the stacking step (4) can be performed before the dielectric layer forming step (2) or after the cathode forming step (5). When a series of steps are performed in a roll-to-roll manner, the thin-walled region forming step (3) and the stacking step (4) are preferably performed before the dielectric layer forming step (2). Since the anode body is reinforced by the metal substrate, it is easy to suppress damage to the anode body during transportation. On the other hand, from the perspective of having little impact on subsequent steps, the thin-walled region forming step (3) and the stacking step (4) are preferably performed after the cathode forming step (5).

[0116] [Method for manufacturing electrolytic capacitor]

[0117] The electrolytic capacitor according to the present embodiment can be manufactured by the following method. The present embodiment includes a method for manufacturing an electrolytic capacitor.

[0118] The method for manufacturing an electrolytic capacitor according to the present embodiment includes: a step of preparing a capacitor element manufactured by the above-described method; and a step of laminating a plurality of capacitor elements and welding anode portions thereof to each other. Figure 8 This is a flowchart showing a method for manufacturing an electrolytic capacitor according to the present embodiment.

[0119] (i) Capacitor element preparation step (S1)

[0120] At least one capacitor element is produced by the above methods (1) to (5).

[0121] (ii) Joining step (S2)

[0122] A plurality of capacitor elements are stacked, and anode portions are bonded to each other.

[0123] At least one of the plurality of capacitor elements may be the capacitor element of the present embodiment. The others may be conventionally known capacitor elements. Preferably, two or more of the plurality of capacitor elements disposed in the electrolytic capacitor are capacitor elements of the present embodiment. In this case, the thin-walled regions are welded together with the metal substrate.

[0124] The welding method is not particularly limited, and any method can obtain the effect brought about by the present embodiment. As welding methods, for example, laser welding, resistance welding, arc welding, gas welding, electron beam welding and brazing can be cited. Laser welding is a method of melting and joining metals by irradiating laser. Resistance welding is a method of melting and joining metals by using the Joule heat generated by energizing. Arc welding is a method of melting and joining metals by using the discharge phenomenon in the air. Gas welding is a method of melting and joining metals using combustible gas. Electron beam welding is a method of melting and joining metals by causing electrons emitted in a vacuum to collide. Brazing is a method of inserting a brazing material with a lower melting point than the base material (in this case, the metal substrate or the anode body) and joining.

[0125] (iii) Lead terminal connection step (S3)

[0126] The anode lead terminal is electrically connected to the anode portion, and the cathode lead terminal is electrically connected to the cathode layer. The electrical connection between the anode portion and the anode lead terminal is performed, for example, by welding them using the above-mentioned method. The electrical connection between the cathode layer and the cathode lead terminal is performed, for example, by bonding the cathode layer and the cathode lead terminal using a conductive adhesive.

[0127] (iv) Sealing step (S4)

[0128] The capacitor element and a portion of the lead terminal may be sealed with a sealing resin. The sealing is performed using a molding technique such as injection molding, insert molding, and compression molding. For example, a composition containing a curable resin or a thermoplastic resin is filled in a predetermined mold so as to cover one end of the capacitor element and the lead terminal, and then heated.

[0129] Industrial Applicability

[0130] The electrolytic capacitor according to the above aspect of the present invention has a reduced ESR and can therefore be used in electrolytic capacitors for various applications requiring low ESR.

[0131] Description of Reference Numerals

[0132] 100: Electrolytic capacitor

[0133] 110: Capacitor element

[0134] 11: Anode

[0135] 11X: Porous Area

[0136] 11Y: Core area

[0137] 11a: Anode

[0138] 11b: Cathode forming part

[0139] 12: Dielectric layer

[0140] 13: Cathode layer

[0141] 131: Solid electrolyte layer

[0142] 132: Cathode lead layer

[0143] 20: Metal substrate

[0144] 120A: Anode lead terminal

[0145] 120B: Cathode lead terminal

[0146] 130: Sealing resin

Claims

1. A capacitor element comprising: an anode body having a porous region on a surface thereof, a dielectric layer covering at least a portion of the anode body, and a cathode layer covering at least a portion of the dielectric layer, The anode body includes an anode portion and a cathode forming portion adjacent to the anode portion and having the cathode layer formed therein. A thin-walled region thinner than the porous region in the cathode forming portion is formed in at least a portion of the porous region of the anode portion, A metal substrate is laminated on at least a portion of the thin-walled region, The metal substrate is denser than the porous region in the cathode-forming portion, The surface of the metal substrate opposite to the surface facing the thin-walled region is roughened.

2. The capacitor element according to claim 1, wherein A surface of the metal substrate opposite to the thin-walled region is roughened.

3. The capacitor element according to claim 1 or 2, wherein: The metal substrate comprises the same metal material as the anode body.

4. The capacitor element according to claim 1 or 2, wherein: In the cathode forming portion, the thickness of the porous region is 95% or more of the thickness of the anode body.

5. The capacitor element according to claim 1 or 2, wherein: The thin-walled region has a compressed layer in which the porous region is compressed. 6 . An electrolytic capacitor comprising a plurality of stacked capacitor elements according to claim 1 .

7. A method for manufacturing a capacitor element, comprising: A preparation step of preparing an anode body having a porous area on the surface; a dielectric layer forming step of forming a dielectric layer covering at least a portion of the anode body; a thin-wall region forming step of compressing or removing a portion of the porous region to form a thin-wall region on the anode body; A lamination step of laminating a metal substrate on at least a portion of the thin-walled region; and a cathode forming step of forming a cathode layer in a cathode forming portion of the anode body excluding the thin-walled region; wherein the laminated metal substrate is denser than the porous region in the cathode forming portion, In the lamination step, a surface of the laminated metal substrate opposite to a surface facing the thin-walled region is roughened.

8. The method for manufacturing a capacitor element according to claim 7, wherein: The thin-walled region forming step is performed in parallel with the laminating step. The metal substrate is arranged to cover a portion of the porous region, and the stacked portion of the metal substrate and the anode body is pressed to compress the porous region to form the thin-walled region, while the metal substrate is stacked on the thin-walled region.

9. The method for manufacturing a capacitor element according to claim 7 or 8, wherein: After the lamination step, the cathode forming step is performed.

10. A method for manufacturing an electrolytic capacitor, comprising: a step of preparing a capacitor element manufactured by the method according to any one of claims 7 to 9; and A joining step of laminating a plurality of the capacitor elements and welding the thin-walled regions together with the metal substrate.

11. The method for manufacturing an electrolytic capacitor according to claim 10, wherein: The joining step is performed by a method selected from the group consisting of laser welding, resistance welding, arc welding, gas welding, electron beam welding and brazing.

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