Electrolytic capacitor and method for manufacturing same

Abstract

This electrolytic capacitor comprises: a capacitor element that includes a positive electrode part and a negative electrode part; and a case that houses the capacitor element. The case includes: a housing having an opening; and a sealing body for closing the opening of the housing. The sealing body includes: a lead part comprising a positive electrode lead part and a negative electrode lead part; a frame part surrounding the lead part; and a sealing resin part that fills a gap between the lead part and the frame part. The positive electrode part of the capacitor element is joined to the negative electrode lead part, and the negative electrode part of the capacitor element is joined to the negative electrode lead part. At least a portion of the inner surface of the housing is covered with an inner wall resin layer.

Description

Electrolytic capacitor and its manufacturing method

[0001] The present disclosure relates to an electrolytic capacitor and a method for manufacturing an electrolytic capacitor, and more particularly to an electrolytic capacitor including a capacitor element and a method for manufacturing the electrolytic capacitor.

[0002] Patent Document 1 discloses a solid electrolytic capacitor including a capacitor element having an anode body including a dielectric layer and a solid electrolyte layer covering at least a portion of the dielectric layer, an exterior resin covering the capacitor element, and a coating layer located between the capacitor element and the exterior resin and containing a fluorine compound.

[0003] International Publication No. 2019 / 230591

[0004] An electrolytic capacitor according to one aspect of the present disclosure includes a capacitor element including an anode portion and a cathode portion, and a case that houses the capacitor element, the case having a housing with an opening and a sealing body that closes the opening of the housing, the sealing body including a lead portion consisting of an anode lead portion and a cathode lead portion, a frame portion that surrounds the lead portion, and a sealing resin portion that fills the space between the lead portion and the frame, the anode portion of the capacitor element being joined to the anode lead portion, and the cathode portion of the capacitor element being joined to the cathode lead portion, and at least a portion of the inner surface of the housing being covered with an inner wall resin layer.

[0005] A method for manufacturing an electrolytic capacitor according to one aspect of the present disclosure includes the steps of: preparing a capacitor element including an anode portion and a cathode portion; a housing having an opening, at least a portion of an inner surface of which is covered with an inner wall resin layer; and a sealing body including a lead portion consisting of an anode lead portion and a cathode lead portion, a frame portion surrounding the lead portion, and a sealing resin portion filling the space between the lead portion and the frame portion; joining the anode lead portion of the sealing body to the anode portion of the capacitor element and joining the cathode lead portion of the sealing body to the cathode portion of the capacitor element; positioning the sealing body so that at least a portion of the sealing body abuts on a first end surface of the inner wall resin layer that is closest to the opening of the housing, thereby closing the opening of the housing with the sealing body to which the capacitor element is joined; and sealing the opening of the housing by welding the sealing body to the opening of the housing.

[0006] According to the present disclosure, it is possible to improve both the airtightness and the voltage resistance of an electrolytic capacitor.

[0007] Fig. 1 is a schematic perspective view of an electrolytic capacitor according to an embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view of an electrolytic capacitor according to an embodiment of the present disclosure taken along line X-X in Fig. 1. Fig. 3 is a schematic exploded view of an electrolytic capacitor according to an embodiment of the present disclosure. Fig. 4 is a schematic perspective cross-sectional view showing a portion of a housing and a sealing body of an electrolytic capacitor according to an embodiment of the present disclosure.

[0008] In the electrolytic capacitor disclosed in Patent Document 1, the conductive polymer of the capacitor element is degraded by external moisture and oxygen permeating the exterior resin. The coating layer prevents external moisture and oxygen from reaching the conductive polymer, but this is not sufficient. Thus, electrolytic capacitors are required to have improved airtightness to prevent the intrusion of external moisture and oxygen. In addition, when the electrolytic capacitor has a metal housing, contact between the anode and cathode of the capacitor element and the housing can cause a short circuit, and therefore, it is also required to prevent such short circuits and improve voltage resistance.

[0009] The present disclosure provides an electrolytic capacitor and a method for manufacturing an electrolytic capacitor that can improve both airtightness and voltage resistance.

[0010] (Embodiments) (1) Overview Electrolytic capacitors according to embodiments will be described below with reference to the drawings. However, the following embodiment is merely one of various embodiments of the present disclosure. The following embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, each figure described in the following embodiments is a schematic diagram, and the ratios of the sizes and thicknesses of the components in the figures do not necessarily reflect the actual dimensional ratios.

[0011] As shown in FIGS. 1 to 3, the electrolytic capacitor 1 of this embodiment includes a capacitor element 10 and a case 20.

[0012] The case 20 has a housing 21 having an opening 211 and a sealing body 22 that closes the opening 211 of the housing 21. At least a portion of the inner surface of the housing 21 is covered with an inner wall resin layer 23.

[0013] Sealing body 22 includes a lead portion 31, a frame portion 32 surrounding lead portion 31, and a sealing resin portion 33 filling the space between lead portion 31 and frame portion 32. Lead portion 31 is made up of an anode lead portion 31A and a cathode lead portion 31B.

[0014] Capacitor element 10 includes an anode portion 11 A and a cathode portion 11 B. Anode portion 11 A of capacitor element 10 is joined to an anode lead portion 31 A. Cathode portion 11 B of capacitor element 10 is joined to a cathode lead portion 31 B.

[0015] In the electrolytic capacitor 1 of this embodiment, the case 20 includes a housing 21 and a sealing body 22. The sealing body 22, which closes the opening of the housing 21, is composed of a lead portion 31, a frame portion 32, and a sealing resin portion 33. Therefore, compared to conventional electrolytic capacitors in which the opening is sealed with a resin such as rubber, materials with low gas permeability can be used for the lead portion 31, the frame portion 32, and the sealing resin portion 33, thereby improving the airtightness of the electrolytic capacitor. In particular, the sealing resin portion 33 is made of a material with lower gas permeability than the resin such as rubber used in conventional electrolytic capacitors, and is formed to fill the gap between the metal lead portion 31 and the frame portion 32. This enhances adhesion between the lead portion 31 and the sealing resin portion 33 and between the frame portion 32 and the sealing resin portion 33, thereby significantly improving the airtightness compared to conventional electrolytic capacitors. Additionally, the electrolytic capacitor 1 of this embodiment has a structure in which at least a portion of the inner surface of the housing 21 is covered with an inner wall resin layer 23. It is believed that this inner wall resin layer 23 suppresses the occurrence of short circuits between the anode portion 11A and the cathode portion 11B of the capacitor element 10 and the housing 21, thereby improving the voltage resistance.

[0016] The electrolytic capacitor 1 of this embodiment has improved airtightness, which can suppress deterioration of the conductive polymer and other components of the capacitor element 10 due to external moisture and oxygen, thereby improving the reliability of the electrolytic capacitor 1. Furthermore, dissipation of liquid components such as the electrolyte solution in the electrolytic capacitor 1 is suppressed, which lengthens the time it takes for the liquid components to disappear (dry up) from the capacitor element 10 even when used for a long period of time or in a high-temperature environment. This improves the reliability of the electrolytic capacitor 1. Additionally, the electrolytic capacitor 1 of this embodiment has improved voltage resistance, which can suppress the occurrence of short circuits between the anode portion 11A and the cathode portion 11B of the capacitor element 10 and the housing 21.

[0017] (2) Details The configuration of the electrolytic capacitor 1 according to this embodiment will be described in more detail below. In this embodiment, as a representative example, the electrolytic capacitor 1 will be described as a hybrid electrolytic capacitor 1 that includes both a solid electrolyte such as a conductive polymer and a liquid component such as an electrolytic solution.

[0018] 2 includes a capacitor element 10 and a case 20. Capacitor element 10 is impregnated with a liquid component (not shown).

[0019] [Capacitor Element] As shown in FIG. 2, the capacitor element 10 is housed in a case 20. The capacitor element 10 includes an anode portion 11A and a cathode portion 11B. For example, the capacitor element 10 includes an anode foil including the anode portion 11A and a cathode foil including the cathode portion 11B. A separator and a conductive polymer serving as a solid electrolyte are disposed between the anode foil and the cathode foil. Examples of conductive polymers include polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene) (PEDOT), and polyaniline. Examples of separator materials include cellulose, polyethylene terephthalate (PET), vinylon, and aramid fiber. The separator may be formed by sandwiching a sheet between the anode foil and the cathode foil, or by folding a long sheet between the anode foil and the cathode foil. The separator can retain an electrolyte, such as an electrolytic solution or a conductive polymer, by impregnation.

[0020] The anode foil includes a metal foil containing a valve metal such as aluminum, tantalum, or niobium, and a dielectric layer formed on the surface of the metal foil. The cathode foil is a metal foil containing a valve metal such as aluminum, tantalum, or niobium.

[0021] 2 and 3 includes a stacked capacitor element 10 as the capacitor element 10. As shown in Fig. 2 and 3, the stacked capacitor element 10 is formed by stacking, for example, an anode foil, a cathode foil, and a separator in a direction from the bottom surface of the housing 21 toward the opening 211.

[0022] The anode portion 11A of the capacitor element 10 is joined to an anode lead portion 31A of the lead portion 31 described below. The cathode portion 11B of the capacitor element 10 is joined to a cathode lead portion 31B. "Joining" means joining two members together. Examples of joining methods that can be used include laser welding, ultrasonic welding, and resistance welding. These joining methods allow the lead portions 31A and 31B to be electrically and mechanically connected to the anode portion 11A and the cathode portion 11B.

[0023] [Case] ​​The case 20 accommodates the capacitor element 10 and the liquid component. As shown in Figures 1 to 3, the case 20 has a housing 21 and a sealing body 22. At least a portion of the housing 21 is covered with an inner wall resin layer 23.

[0024] (Housing) The housing 21 is a member having an opening 211, and the shape of the housing 21 is usually a hollow cube or rectangular parallelepiped with one face open and a closed-end square cylinder, or the like.

[0025] The material of the housing 21 is usually a metal, such as aluminum, stainless steel, copper, iron, brass, or an alloy of these.

[0026] The metal housing 21 in the shape of a rectangular cylinder with a bottom can be easily formed by pressing, and therefore can be mass-produced. By using this, the mass production of the electrolytic capacitor 1 can be improved.

[0027] (Sealing Body) The sealing body 22 is a member that closes the opening 211 of the housing 21. The sealing body 22 includes a lead portion 31, a frame portion 32, and a sealing resin portion 33.

[0028] (Lead Portion) Lead portion 31 is made up of anode lead portion 31A and cathode lead portion 31B, and is a member that serves as a current collector by having a portion of its surface exposed to the outside of case 20. This current collector is joined by solder or the like to a substrate on which electrolytic capacitor 1 is mounted. Lead portion 31 is typically made of a metal, such as aluminum, stainless steel, copper, iron, brass, or an alloy thereof.

[0029] The lead portions 31A and 31B preferably have a shape including a flat surface for connection with the mounting board, such as a simple flat plate shape or an L-shaped plate shape.

[0030] 2, lead portions 31A, 31B typically protrude from sealing body 22 toward the inside of casing 21. Anode lead portion 31A is joined to anode portion 11A of capacitor element 10 and is electrically connected to anode foil 12A via anode portion 11A. Cathode lead portion 31B is joined to cathode portion 11B of capacitor element 10 and is electrically connected to cathode foil 12B via cathode portion 11B.

[0031] Each of the leads 31A, 31B may be a single flat-plate-shaped member, or may include an inner lead 311 facing the interior of the housing 21 and an outer lead 312 located on the opposite side of the inner lead 311, as shown in FIGS. 2 and 3 . Such leads 31A, 31B can be fabricated by joining the flat-plate-shaped member of the inner lead 311 and the flat-plate-shaped member of the outer lead 312, for example, by welding. In such leads 31A, 31B, the inner lead 311 and the outer lead 312 may be different in size or material. For example, if the electrical conductivity of the material of the inner lead 311 is lower than that of the material of the outer lead 312, the cross-sectional area of ​​the inner lead 311 (cross-sectional area perpendicular to the direction from the inside to the outside of the housing 21) can be made larger than the cross-sectional area of ​​the outer lead 312 to prevent the electrical conductivity of the entire leads 31A, 31B from being limited by the material with lower electrical conductivity. Furthermore, the contact area between the lead portions 31A and 31B and the anode portion 11A and the cathode portion 11B can be increased, and the connection resistance can be further reduced.

[0032] It is preferable that the first metal constituting the inner lead portion 311 and the second metal constituting the outer lead portion 312 are different. In this case, the first metal is, for example, aluminum, and the second metal is, for example, copper. This allows the inner lead portion 311 to be made of the same material as the anode portion 11A and the cathode portion 11B, thereby achieving strong bonding, and allows the outer lead portion 312 to be made of a material that further improves solder connectivity. Even when the inner lead portion 311 and the outer lead portion 312 are made of different metals, the bonding interface between the inner lead portion 311 and the outer lead portion 312 is covered with the sealing resin portion 33, preventing moisture from reaching the interface from the outside, thereby suppressing the occurrence of pitting corrosion and the like. "The first metal and the second metal are different" means that the first metal and the second metal are not identical, and "the first metal and the second metal are identical" means that the compositions of the metal components contained in the first metal and the second metal are identical, i.e., the types and amounts of the metal components are the same.

[0033] Furthermore, the first metal and the second metal in the lead portion 31 may be the same. In this case, both the first metal and the second metal are, for example, aluminum. This makes it easier to join by welding between the anode portion 11A and the lead portion 31 and between the cathode portion 11B and the lead portion 31. In this case, plating the outer surface of the lead portion 31 with Ni, Sn, or the like can improve connectivity with solder.

[0034] To improve solder connectivity, it is preferable to provide irregularities on the mounting surface of outer lead 312 by roughening or forming regular recesses. These irregularities can also be formed by deformation such as knurling when joining anode foil 12A and cathode foil 12B or when bonding inner lead 311 and outer lead 312 together.

[0035] (Frame portion) The frame portion 32 is a member that surrounds the lead portion 31. That is, as shown in FIG. 1 , the frame portion 32 is disposed around the lead portion 31 with the sealing resin portion 33 interposed therebetween, and is usually disposed around the entire outer periphery of the sealing body 22.

[0036] The frame portion 32 is usually made of a metal, such as aluminum, stainless steel, copper, iron, brass, or an alloy thereof.

[0037] It is preferable that at least a portion of the inner surface of the frame portion 32 is covered with the sealing resin portion 33. This prevents the anode portion 11A and the cathode portion 11B of the capacitor element 10 from coming into contact with the housing 21 via the frame portion 32, thereby preventing a short circuit from occurring. In other words, the voltage resistance of the electrolytic capacitor 1 can be further improved.

[0038] (Sealing Resin Portion) The sealing resin portion 33 is a member that fills the gap between the lead portion 31 and the frame portion 32. That is, as shown in FIG. 1 , the sealing resin portion 33 is formed so that there are no gaps between the anode lead portion 31A and the cathode lead portion 31B, between the anode lead portion 31A and the frame portion 32, and between the cathode lead portion 31B and the frame portion 32. The sealing resin portion 33 is formed so that there is good adhesion between the frame portion 32 and the sealing resin portion 33, between the anode lead portion 31A and the sealing resin portion 33, and between the cathode lead portion 31B and the sealing resin portion 33.

[0039] Thermoplastic resins are typically used as the material for the sealing resin portion 33 because they can be injection molded. Among these, polybutylene terephthalate (PBT) and polyphenylene sulfide (PPS) are preferred. These resins have particularly low gas permeability, which can further improve the airtightness of the electrolytic capacitor 1. Furthermore, their high heat resistance further improves reliability in high-temperature environments.

[0040] The shape of the sealing resin portion 33 is not particularly limited, and may be a flat plate shape with a substantially uniform thickness, a shape that fits under the frame portion 32 along the frame portion 32 having an L-shaped cross section as shown in Fig. 4, or any other shape. The sealing resin portion 33 may not be present below the frame portion 32, and the frame portion 32 may abut against the upper end surface (first end surface 23A) of the inner wall resin layer 23 described below.

[0041] In the sealing body 22, it is preferable that the surfaces of the lead portions 31 that come into contact with the sealing resin portion 33 and the surfaces of the frame portion 32 that come into contact with the sealing resin portion 33 are surface-treated surfaces. In other words, when producing the sealing body 22, it is preferable to surface-treat the outer surfaces of the lead portions 31, the surface of the inner lead portion 311 facing the outer lead portion 312, and the inner peripheral side surface of the frame portion 32. This improves the adhesion between the lead portions 31 and the sealing resin portion 33 and between the frame portion 32 and the sealing resin portion 33, thereby further improving the airtightness of the electrolytic capacitor 1.

[0042] Examples of surface treatments include chemical surface treatments, surface roughening treatments, or both. Chemical surface treatments include immersion in a chemical conversion solution such as an ammonium adipate solution followed by heat treatment, or immersion in a chemical conversion solution followed by application of a voltage, thereby forming a chemical conversion coating. Surface roughening can also be performed by etching, which can be performed by, for example, direct current electrolysis or alternating current electrolysis.

[0043] (Inner Wall Resin Layer) The inner wall resin layer 23 is a layer that covers at least a portion of the inner surface of the housing 21. The resin layer "covering at least a portion of the inner surface" means that at least a portion of the inner surface overlaps with the resin layer when viewed from inside the housing 21. The inner wall resin layer 23 may or may not be in contact with at least a portion of the inner surface of the housing 21.

[0044] The inner wall resin layer 23 may be formed by insert molding on the inner surface of the housing 21, or may be formed by applying a resin to the inner surface of the housing 21. The inner wall resin layer 23 may also be a container formed of resin that is placed inside the housing 21. Of these, using an insert molded product as the inner wall resin layer 23 is preferable from the viewpoint of mass production.

[0045] The thickness of the inner wall resin layer 23 is, for example, 0.1 mm to 1.0 mm, and preferably 0.3 mm to 0.8 mm. By setting the thickness of the inner wall resin layer 23 within this range, the voltage resistance of the electrolytic capacitor 1 can be further improved.

[0046] The material of the inner wall resin layer 23 is, for example, a thermoplastic resin, and it is preferable to use a resin that can be insert molded and has excellent electrolyte resistance characteristics. Examples of such resins include polyphenylene sulfide (PPS) and polybutylene terephthalate (PBT).

[0047] From the viewpoint of improving voltage resistance, it is preferable that the inner wall resin layer 23 covers at least half of the total area of ​​the inner surface of the housing 21 on the bottom side, and it is more preferable that it covers the entire area of ​​the inner surface of the housing 21.

[0048] Furthermore, the inner wall resin layer 23 can be used to enable the sealing body 22 to be positioned and placed quickly and reliably relative to the housing 21 during the manufacture of the electrolytic capacitor 1. This not only improves the sealing reliability of the case 20 in the electrolytic capacitor 1 and enables mass production, but also further reduces gaps between the housing 21 and the sealing body 22, thereby further improving the airtightness of the electrolytic capacitor 1.

[0049] 4 , when the end face of inner wall resin layer 23 closest to opening 211 of housing 21 is defined as first end face 23A, it is preferable that at least a portion of the inner surface of sealing body 22 abuts against first end face 23A. In this case, the presence of first end face 23A allows sealing body 22 to be positioned and installed quickly and reliably. This makes it possible to tightly contact opening face 212 of housing 21 with sealing body 22 and join the butted boundary by welding or the like, without the need to create a step in the housing near the end near opening face 212 of housing 21 by cutting or other processes that are difficult to mass-produce.

[0050] 4 , when the distance between first end surface 23A of inner wall resin layer 23 and opening surface 212 of housing 21 is D and the thickness of the portion of sealing body 22 that abuts against first end surface 23A is d, D and d are preferably the same. In this case, when sealing body 22 is fitted to opening 211 of housing 21, the upper surface of sealing body 22 and opening surface 212 of housing 21 become flush with each other, making it possible to join sealing body 22 to housing 21 by welding or the like with high reliability.

[0051] It is preferable that sealing body 22 be joined to opening 211 of housing 21 to seal opening 211. By joining sealing body 22 to housing 21 in this way and sealing opening 211, the gap between housing 21 and sealing body 22 can be further reduced, thereby further improving the airtightness of electrolytic capacitor 1. This joining is preferably performed by welding, from the viewpoint of further improving the airtightness.

[0052] The sealing body 22 is preferably an integrated body of the lead portions 31, the frame portion 32, and the sealing resin portion 33. That is, the sealing body 22 is preferably formed by injection molding the sealing resin portion 33 onto the lead portions 31 and the frame portion 32, i.e., by insert molding. By using an insert-molded body as the sealing body 22 in this way, it is possible to further improve the adhesion between the lead portions 31 and the sealing resin portion 33 and between the frame portion 32 and the sealing resin portion 33, and as a result, it is possible to further improve the airtightness of the electrolytic capacitor 1.

[0053] (Liquid Component) The liquid component is impregnated into capacitor element 10. As a result, the liquid component is contained within case 20. More specifically, the liquid component is impregnated into separator 13 of capacitor element 10 and the like.

[0054] The liquid component may be, for example, an electrolyte solution.

[0055] The electrolytic solution may be an organic solvent, for example. Examples of the organic solvent include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol; sulfone compounds such as sulfolane, dimethyl sulfoxide, and diethyl sulfoxide; lactone compounds such as γ-butyrolactone and γ-valerolactone; carbonate compounds such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and fluoroethylene carbonate; diether compounds of polyhydric alcohols such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; and monohydric alcohols such as methanol, ethanol, and propanol.

[0056] The electrolytic solution may contain a solute, such as an acid component such as an organic acid, an inorganic acid, or a complex acid compound of an organic acid and an inorganic acid; a base component such as an amine or a quaternary ammonium salt; a salt of an acid and a base; a nitro compound; or a phenol compound.

[0057] (Modifications) The above embodiment is merely one of various embodiments of the present disclosure, and various modifications can be made to the above embodiment depending on the design and the like as long as the object of the present disclosure can be achieved.

[0058] In the above embodiment, the electrolytic capacitor 1 is a hybrid electrolytic capacitor 1 having both a solid electrolyte and a liquid component as the electrolyte, but this is not limited to this, and the electrolytic capacitor 1 may have only one of a solid electrolyte and a liquid component.

[0059] In the above embodiment, the shape of the housing 21 is a rectangular cylinder with a bottom, as shown in FIG. 3 , but this is not limited to this, and other shapes, such as a cylindrical shape with a bottom, may be used depending on the location where the electrolytic capacitor 1 is to be mounted, etc.

[0060] In the above embodiment, a stacked type capacitor element 10 is used as the capacitor element 10, but this is not limited to this, and other types of capacitor elements 10, such as a wound type, can also be used. The wound type capacitor element 10 includes an anode foil, a cathode foil, a separator, and a conductive polymer, and the anode foil, cathode foil, and separator are wound around a winding axis that intersects with the direction from the bottom surface of the housing 21 toward the opening 211.

[0061] <Method for Manufacturing Electrolytic Capacitor> The electrolytic capacitor 1 of this embodiment can be simply and reliably manufactured by a manufacturing method including, for example, a preparation step, a joining step, an opening closing step, and a sealing step. When manufacturing an electrolytic capacitor 1 having an electrolyte solution inside, this manufacturing method may include an impregnation step before the sealing step. Each step will be described below.

[0062] [Preparation Step] In this step, the capacitor element 10, the housing 21 having the opening 211 and at least a portion of the inner surface covered with the inner wall resin layer 23, and the sealing body 22 are prepared. The sealing body 22 includes a lead portion 31, a frame portion 32, and a sealing resin portion 33. The capacitor element 10 includes an anode portion 11A and a cathode portion 11B. The lead portion 31 is composed of an anode lead portion 31A and a cathode lead portion 31B, and the frame portion 32 surrounds the lead portion 31. The sealing resin portion 33 fills the space between the lead portion 31 and the frame portion 32. The capacitor element 10 may be either a stacked type or a wound type.

[0063] The housing 21 having the opening 211 and at least a portion of the inner surface covered with the inner wall resin layer 23 is preferably formed by injection molding the inner wall resin layer 23 into the housing 21. That is, it is preferable to perform insert molding by placing the housing 21 in a mold and injecting the resin that forms the inner wall resin layer 23. This allows for mass production.

[0064] Furthermore, sealing body 22 is preferably formed by injection molding sealing resin portion 33 onto lead portion 31 and frame portion 32. That is, it is preferable to place lead portion 31 and frame portion 32 in a mold, and then inject resin that forms sealing resin portion 33 to perform insert molding.

[0065] When the above-described injection molding is performed, it is preferable to perform at least one of a chemical surface treatment and a surface roughening treatment beforehand on the surfaces of the lead portions 31 and the frame portion 32 that come into contact with the sealing resin portion 33. By performing such a chemical surface treatment and a surface roughening treatment in advance on the surfaces of the lead portions 31 and the frame portion 32 that come into contact with the sealing resin portion 33 by injection molding using the above-described method, it is possible to further improve the adhesion between the lead portions 31 and the sealing resin portion 33 and between the frame portion 32 and the sealing resin portion 33, and as a result, it is possible to further improve the airtightness of the electrolytic capacitor 1.

[0066] [Bonding Step] In this step, anode lead portion 31A of sealing body 22 is joined to anode portion 11A of capacitor element 10, and cathode lead portion 31B of sealing body 22 is joined to cathode portion 11B of capacitor element 10.

[0067] Examples of joining methods include laser welding, ultrasonic welding, and resistance welding.

[0068] The joining is preferably performed by laser welding. Laser welding also allows for collective welding. First, multiple sets (e.g., 30 sets) of anode foils, separators, and cathode foils are stacked on the inner lead portion 311A ​​of the anode lead portion 31A and the inner lead portion 311B of the cathode lead portion 31B. Next, collective welding can be performed by irradiating the uppermost anode foil and cathode foil with a laser. This method allows for easy joining of the anode lead portion 31A to the anode portion 11A and the cathode lead portion 31B to the cathode portion 11B. Furthermore, it is possible to simultaneously join the anode portions 11A of multiple anode foils 12A together and the cathode portions 11B of multiple cathode foils 12B together. Welding eliminates connection interface resistance, which contributes to lowering the resistance of the lead portion 31 compared to conventional crimping connection methods. It also shortens the manufacturing cycle time.

[0069] [Opening Closing Process] In this process, the sealing body 22 is positioned so that at least a portion of the sealing body 22 abuts the first end face 23A of the inner wall resin layer 23 that is closest to the opening 211 of the housing 21, thereby closing the opening 211 of the housing 21 with the sealing body 22 to which the capacitor element 10 is bonded.

[0070] In this step, by adopting such a configuration, sealing body 22 can be positioned and disposed relative to housing 21 quickly and reliably.

[0071] [Impregnation Step] In this step, the electrolyte solution is impregnated into the capacitor element 10. This step may be performed by introducing the electrolyte solution into the housing 21 that houses the capacitor element 10. Specifically, the electrolyte solution is impregnated into the separator 13 of the capacitor element 10, etc. The impregnation step may be performed before the placement step. In this case, the electrolyte solution is impregnated into the capacitor element 10 by, for example, immersing the capacitor element 10 in the electrolyte solution.

[0072] [Sealing Step] In this step, the sealing body 22 is welded to the opening 211 of the housing 21 to seal the opening 211 .

[0073] This step is performed by welding the metal of the frame portion 32 of the sealing body 22 to the metal of the edge of the opening 211 of the housing 21 .

[0074] In this manner, the electrolytic capacitor 1 having improved airtightness and voltage resistance can be easily and reliably manufactured.

[0075] (Summary) As is clear from the above-described embodiment and modifications, the present disclosure includes the following aspects. In the following, reference numerals are given in parentheses only to clarify the correspondence with the embodiment.

[0076] The electrolytic capacitor (1) of the first aspect includes a capacitor element (10) and a case (20). The capacitor element (10) includes an anode portion (11A) and a cathode portion (11B). The case (20) houses the capacitor element (10). The case (20) includes a housing (21) having an opening (211) and a sealing body (22) that closes the opening (211) of the housing (21). The sealing body (22) includes a lead portion (31) consisting of an anode lead portion (31A) and a cathode lead portion (31B), a frame portion (32) that surrounds the lead portion (31), and a sealing resin portion (33) that fills the space between the lead portion (31) and the frame portion (32). The anode portion (11A) of the capacitor element (10) is joined to the anode lead portion (31A), and the cathode portion (11B) of the capacitor element (10) is joined to the cathode lead portion (31B). At least a portion of the inner surface of the housing (21) is covered with an inner wall resin layer (23).

[0077] According to the first aspect, the electrolytic capacitor (1) can improve both airtightness and voltage resistance.

[0078] The electrolytic capacitor (1) of the second aspect is the electrolytic capacitor (1) of the first aspect, further comprising a liquid component housed in the case (20). The liquid component is impregnated into the capacitor element (10).

[0079] According to the second aspect, the electrolytic capacitor (1) has improved airtightness, which can further suppress the decrease over time of the liquid component contained therein. Furthermore, the electrolytic capacitor (1) has improved voltage resistance, which can suppress the occurrence of short circuits, even when the electrolytic capacitor (1) contains a liquid component.

[0080] In the electrolytic capacitor (1) of the third aspect, in the first or second aspect, at least a part of the inner surface of the sealing body (22) abuts against the first end surface (23A) of the inner wall resin layer (23) that is closest to the opening (211) of the housing (21).

[0081] According to the third aspect, when manufacturing the electrolytic capacitor (1), the sealing body (22) can be quickly and reliably placed on the housing (21).

[0082] In the electrolytic capacitor (1) of the fourth aspect, in the third aspect, the distance (D) between the first end surface (23A) of the inner wall resin layer (23) and the opening surface (212) of the housing (21) is the same as the thickness (d) of the portion of the sealing body (22) that abuts against the first end surface (23A).

[0083] According to the fourth aspect, when manufacturing the electrolytic capacitor (1), the sealing body (22) can be quickly and reliably placed on the housing (21).

[0084] In the electrolytic capacitor (1) of the fifth aspect, in any one of the first to fourth aspects, at least a part of the inner surface of the frame portion (32) of the sealing body (22) is covered with a sealing resin portion (33).

[0085] According to the fifth aspect, the electrolytic capacitor (1) can further improve the voltage resistance.

[0086] In the electrolytic capacitor (1) of the sixth aspect, in any one of the first to fifth aspects, the sealing body (22) is an integrated body of the lead portion (31), the frame portion (32), and the sealing resin portion (33).

[0087] According to the sixth aspect, the electrolytic capacitor (1) can have further improved airtightness.

[0088] In the electrolytic capacitor (1) of the seventh aspect, in any one of the first to sixth aspects, the surfaces of the lead portion (31) and the frame portion (32) that come into contact with the sealing resin portion (33) are surface-treated surfaces.

[0089] According to the seventh aspect, the electrolytic capacitor (1) can have further improved airtightness.

[0090] In the electrolytic capacitor (1) of the eighth aspect, in any one of the first to seventh aspects, the sealing body (22) is joined to the opening (211) of the housing (21) to seal the opening (211).

[0091] According to the eighth aspect, the electrolytic capacitor (1) can have further improved airtightness.

[0092] In the electrolytic capacitor (1) of the ninth aspect, in any one of the first to eighth aspects, the lead portion (31) includes an inner lead portion (311) facing the inside of the housing (21) and an outer lead portion (312) located on the opposite side of the inner lead portion (311). The first metal constituting the inner lead portion (311) is different from the second metal constituting the outer lead portion (312).

[0093] According to the ninth aspect, the solder connectivity of the outer lead portion (312) can be improved.

[0094] In the electrolytic capacitor (1) of the tenth aspect, in any one of the first to ninth aspects, the lead portion (31) includes an inner lead portion (311) facing the inside of the housing (21) and an outer lead portion (312) located on the opposite side of the inner lead portion (311). The first metal constituting the inner lead portion (311) and the second metal constituting the outer lead portion (312) are the same.

[0095] According to the tenth aspect, the lead portion (31) can be easily produced by welding.

[0096] In an eleventh aspect of the electrolytic capacitor (1), in any one of the first to tenth aspects, the capacitor element (10) includes an anode foil including an anode portion (11A), a cathode foil including a cathode portion (11B), and a separator and a conductive polymer disposed between the anode foil and the cathode foil. The anode foil, the cathode foil, and the separator are stacked in a direction from the bottom surface of the housing (21) toward the opening (211).

[0097] According to the eleventh aspect, the electrolytic capacitor (1) can improve both airtightness and voltage resistance even when the capacitor element (10) is a laminated type.

[0098] In a twelfth aspect of the electrolytic capacitor (1), in any one of the first to eleventh aspects, the capacitor element (10) includes an anode foil including an anode portion (11A), a cathode foil including a cathode portion (11B), and a separator and a conductive polymer disposed between the anode foil and the cathode foil. The anode foil, the cathode foil, and the separator are wound around a winding axis in a direction intersecting a direction from the bottom surface of the housing (21) toward the opening (211).

[0099] According to the twelfth aspect, the electrolytic capacitor (1) can improve both the airtightness and the voltage resistance even when the capacitor element (10) is of a wound type.

[0100] A method for manufacturing an electrolytic capacitor (1) according to a thirteenth aspect includes a preparation step, a joining step, an opening closing step, and a sealing step. The preparation step includes preparing a capacitor element (10) including an anode portion (11A) and a cathode portion (11B), a housing (21) having an opening (211) and at least a portion of the inner surface of which is covered with an inner wall resin layer (23), and a sealing body (22) including a lead portion (31) consisting of an anode lead portion (31A) and a cathode lead portion (31B), a frame portion (32) surrounding the lead portion (31), and a sealing resin portion (33) filling the gap between the lead portion (31) and the frame portion (32). In the joining step, the anode lead portion (31A) of the sealing body (22) is joined to the anode portion (11A) of the capacitor element (10), and the cathode lead portion (31B) of the sealing body (22) is joined to the cathode portion (11B) of the capacitor element (10). In the opening closing step, the sealing body (22) is positioned so that at least a portion of the sealing body (22) abuts against a first end surface (23A) of the inner wall resin layer (23) that is closest to the opening (211) of the housing (21), thereby closing the opening (211) of the housing (21) with the sealing body (22) joined to the capacitor element (10). In the sealing step, the opening (211) is sealed by welding the sealing body (22) to the opening (211) of the housing (21).

[0101] According to the thirteenth aspect, an electrolytic capacitor (1) having improved airtightness and voltage resistance can be easily and reliably manufactured.

[0102] The method for manufacturing an electrolytic capacitor (1) of the fourteenth aspect is the thirteenth aspect, further comprising a step of impregnating the capacitor element (10) with an electrolytic solution before the step of sealing the opening (211).

[0103] According to the fourteenth aspect, an electrolytic capacitor (1) containing an electrolyte solution with improved airtightness and voltage resistance can be easily and reliably manufactured.

[0104] In the manufacturing method of the electrolytic capacitor (1) of the fifteenth aspect, in the thirteenth or fourteenth aspect, the sealing body (22) is formed by injection molding a sealing resin portion (33) onto the lead portion (31) and the frame portion (32).

[0105] According to the fifteenth aspect, an electrolytic capacitor (1) having improved airtightness and voltage resistance can be easily and reliably manufactured.

[0106] In the method for manufacturing the electrolytic capacitor (1) of the sixteenth aspect, in any one of the thirteenth to fifteenth aspects, before the sealing resin portion (33) is injection molded, at least one of a chemical surface treatment and a roughening treatment is applied to the surfaces of the lead portion (31) and the frame portion (32) that come into contact with the sealing resin portion (33).

[0107] According to the sixteenth aspect, an electrolytic capacitor (1) having improved airtightness and voltage resistance can be easily and reliably manufactured.

[0108] In a seventeenth aspect of the method for manufacturing an electrolytic capacitor (1), in any one of the thirteenth to sixteenth aspects, the anode lead portion (31A) and the anode portion (11A) are joined by laser welding, and the cathode lead portion (31B) and the cathode portion (11B) are joined by laser welding.

[0109] According to the seventeenth aspect, a capacitor element (10) having reduced connection resistance between the lead portions (31A, 31B) and the anode portion (11A) and the cathode portion (11B) can be manufactured in a shorter manufacturing takt time.

[0110] REFERENCE SIGNS LIST 1 electrolytic capacitor 10 capacitor element 11A anode portion 11B cathode portion 20 case 21 housing 22 sealing body 23 inner wall resin layer 31 lead portion 31A anode lead portion 31B cathode lead portion 32 frame portion 33 sealing resin portion

Claims

1. An electrolytic capacitor comprising: a capacitor element including an anode portion and a cathode portion; and a case accommodating the capacitor element, wherein the case has a housing having an opening and a sealing body closing the opening of the housing, the sealing body including lead portions consisting of an anode lead portion and a cathode lead portion, a frame portion surrounding the lead portions, and a sealing resin portion filling the gap between the lead portions and the frame portion, wherein the anode portion of the capacitor element is joined to the anode lead portion, and the cathode portion of the capacitor element is joined to the cathode lead portion, and at least a portion of the inner surface of the housing is covered with an inner wall resin layer.

2. The electrolytic capacitor according to claim 1, further comprising a liquid component housed in the case, the liquid component being impregnated into the capacitor element.

3. The electrolytic capacitor according to claim 1, wherein at least a portion of the inner surface of the sealing body abuts against a first end surface of the inner wall resin layer that is closest to the opening of the housing.

4. The electrolytic capacitor according to claim 3, wherein the distance between the first end face of the inner wall resin layer and the opening face of the housing is the same as the thickness of the portion of the sealing body that abuts against the first end face.

5. The electrolytic capacitor according to claim 1, wherein at least a portion of the inner surface of the frame portion of the sealing body is covered with the sealing resin portion.

6. The electrolytic capacitor according to claim 1, wherein the sealing body is an integrated body of the lead portion, the frame portion, and the sealing resin portion.

7. The electrolytic capacitor according to claim 1, wherein the surfaces of the lead portion and the frame portion that come into contact with the sealing resin portion are surface-treated surfaces.

8. The electrolytic capacitor according to claim 1, wherein the sealing body is joined to the opening of the housing to seal the opening.

9. The electrolytic capacitor according to claim 1, wherein the lead portion includes an inner lead portion facing the interior of the housing and an outer lead portion located on the opposite side of the inner lead portion, and the first metal constituting the inner lead portion is different from the second metal constituting the outer lead portion.

10. The electrolytic capacitor according to claim 1, wherein the lead portion includes an inner lead portion facing the interior of the housing and an outer lead portion located on the opposite side of the inner lead portion, and the first metal constituting the inner lead portion and the second metal constituting the outer lead portion are the same.

11. The electrolytic capacitor according to claim 1, wherein the capacitor element includes an anode foil including the anode portion, a cathode foil including the cathode portion, and a separator and a conductive polymer disposed between the anode foil and the cathode foil, and the anode foil, the cathode foil, and the separator are stacked in a direction from the bottom surface of the casing toward the opening.

12. The electrolytic capacitor according to claim 1, wherein the capacitor element comprises an anode foil including the anode portion, a cathode foil including the cathode portion, a separator and a conductive polymer disposed between the anode foil and the cathode foil, and the anode foil, the cathode foil, and the separator are wound around a winding axis that intersects with the direction from the bottom surface of the casing toward the opening.

13. A method for manufacturing an electrolytic capacitor, comprising the steps of: preparing a capacitor element including an anode portion and a cathode portion; a housing having an opening and at least a portion of the inner surface covered with an inner wall resin layer; a sealer including a lead portion consisting of an anode lead portion and a cathode lead portion, a frame portion surrounding the lead portion, and a sealing resin portion filling the space between the lead portion and the frame portion; joining the anode lead portion of the sealer to the anode portion of the capacitor element, and joining the cathode lead portion of the sealer to the cathode portion of the capacitor element; positioning the sealer so that at least a portion of the sealer abuts a first end face of the inner wall resin layer closest to the opening of the housing, thereby closing the opening of the housing with the sealer to which the capacitor element is joined; and sealing the opening of the housing by welding the sealer to the opening.

14. The method for manufacturing an electrolytic capacitor according to claim 13, further comprising the step of impregnating the capacitor element with an electrolyte solution before the step of sealing the opening.

15. The method for manufacturing an electrolytic capacitor according to claim 13, wherein the sealing body is formed by injection molding the sealing resin portion onto the lead portion and the frame portion.

16. The method for manufacturing an electrolytic capacitor according to claim 13, wherein, before the sealing resin portion is injection molded, the surfaces of the lead portion and the frame portion that come into contact with the sealing resin portion are subjected to at least one of a chemical surface treatment and a surface roughening treatment.

17. The method for manufacturing an electrolytic capacitor according to claim 13, wherein the anode lead portion and the anode portion are joined by laser welding, and the cathode lead portion and the cathode portion are joined by laser welding.

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