Electrolytic capacitor and method for manufacturing same

Abstract

An electrolytic capacitor is provided with a first electrode, a second electrode, a container, and a sealing member, the first electrode having a first electrode foil, two or more first internal leads, and a first external lead, a portion of each of the two or more first internal leads being overlapped to form a laminated portion, the first external lead having a first portion, a second portion, and a third portion, the sealing member includes a first portion having a top portion tapped into a first surface of the laminated portion, a second portion penetrating the laminated portion, and a third portion protruding from a second surface of the laminated portion opposite to the first surface and penetrating the sealing member, the second portion being in contact with an inner peripheral surface of the laminated portion.

Description

[0001] Cross-referencing of related applications

[0002] This application claims priority to Japanese Patent Application No. 2023-053815, filed on March 29, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to electrolytic capacitors and methods for manufacturing the same. Background Technology

[0004] Patent Document 1 discloses "a method for manufacturing an electrolytic capacitor, which is a method for manufacturing an electrolytic capacitor having a first electrode and a second electrode, the method comprising: a first connection step, in which a foil-shaped first internal lead is connected to a first electrode foil; a second connection step, after the first connection step, in which a rod-shaped first external lead is connected to the first internal lead to obtain the first electrode; an insertion step, after the second connection step, in which the first external lead is inserted into an insertion hole of a sealing member; a receiving step, after the insertion step, in which the first electrode and the second electrode are received in a container; and a sealing step, after the receiving step, in which the opening of the container is sealed with the sealing member."

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2021 / 172440 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Patent Document 1 describes that "the first internal lead has a through hole. In the second connection process, after the first external lead is inserted into the through hole, the two main surfaces of the first internal lead are pressed to flatten one end of the first external lead, thereby causing the first external lead to be locked to the first internal lead."

[0010] However, the proposal in Patent Document 1 does not take into account the connection resistance between the first external lead and the first internal lead, so it cannot sufficiently reduce the equivalent series resistance (ESR) and thus cannot improve the allowable value of ripple current.

[0011] Methods for solving problems

[0012] One aspect of the present invention relates to an electrolytic capacitor comprising: a first electrode, a second electrode, a container for receiving the first electrode and the second electrode, and a sealing member for sealing the opening of the container. The first electrode has a first electrode foil, two or more first internal leads connected to the first electrode foil, and a first external lead connected to the two or more first internal leads. A portion of each of the two or more first internal leads is overlapped to form a laminate. The first external lead has a first portion, a second portion continuous with the first portion, and a third portion continuous with the second portion. The first portion has a top that is hemmed into a first surface of the laminate. The second portion extends through the laminate. The third portion protrudes from the second surface of the laminate on the side opposite to the first surface and extends through the sealing member. The second portion contacts the inner peripheral surface of the laminate.

[0013] Another aspect of the present invention relates to a method for manufacturing an electrolytic capacitor, the method comprising: a first connection step of connecting two or more first internal leads to a first electrode foil; a second connection step of connecting the two or more first internal leads to first external leads after the first connection step to obtain a first electrode; an insertion step of inserting the first external leads into an insertion hole of a sealing member after the second connection step; a housing step of housing the first electrode and the second electrode in a container after the insertion step; and a sealing step of sealing the opening of the container with the sealing member after the housing step, wherein the two or more first internal leads each have a through hole, and the first... The external lead has a columnar portion with a maximum diameter larger than the maximum diameter of the through hole. The columnar portion has a first portion including one end of the columnar portion, a second portion continuous with the first portion, and a third portion continuous with the second portion and not passing through the through hole in the insertion process. In the second connection process, the columnar portion is inserted into the through hole by a stacked portion in which a portion of each of the two or more first internal leads is overlapped. After the first portion protrudes from the first surface of the stacked portion, the first portion is flattened toward the first surface of the stacked portion. While forming a top that is tightly pressed against the first surface, the second portion is engaged with the inner peripheral surface of the stacked portion.

[0014] Invention Effects

[0015] According to this application, the permissible ripple current of electrolytic capacitors can be increased.

[0016] The novel features of the invention are set forth within the scope of the appended claims; however, the invention should be more fully understood, in both its composition and content, together with its other objects and features, by referring to the following detailed description of the accompanying drawings. Attached Figure Description

[0017] Figure 1 It is a top view schematically showing the state in which the first electrode foil connected with the first internal lead, the second electrode foil connected with the second internal lead, and the spacer are arranged in a stacking order.

[0018] Figure 2 It is a three-dimensional diagram schematically representing the process of connecting internal leads to external leads.

[0019] Figure 3 This is a schematic cross-sectional view illustrating the second connection process of connecting the internal lead to the external lead.

[0020] Figure 4 This is a side view of the wound body after the second connection process.

[0021] Figure 5 This is a side view of the wound body after the insertion process.

[0022] Figure 6 It is a side view of the cross-section of the bottom casing and sealing components of an electrolytic capacitor.

[0023] Figure 7 This is a partial schematic diagram of the external leads representing the changes in the flange.

[0024] Figure 8 This is a schematic cross-sectional view illustrating another example of the second connection process where an internal lead connects to an external lead. Detailed Implementation

[0025] The following describes embodiments of the electrolytic capacitor of this application using examples; however, this application is not limited to the examples described below. In the following description, specific values ​​and materials are sometimes shown; however, other values ​​and materials can be applied as long as the effects of this application are achieved. In this specification, references such as "value A to value B" include both value A and value B, and can be changed to "value A or higher and value B or lower." In the following description, when lower and upper limits of values ​​relating to specific physical properties, conditions, etc., are shown, any combination of either the shown lower limit and either the shown upper limit can be used as long as the lower limit is not higher than the upper limit. When multiple materials are shown, one can be selected for use alone, or two or more can be used in combination.

[0026] "Electrolytic capacitor" can be renamed "solid electrolytic capacitor" or "solid-liquid hybrid electrolytic capacitor," and "capacitor" can also be renamed "capacitance." At least a portion of the solid electrolyte layer is formed by a "conductive polymer."

[0027] (Electrolytic capacitor)

[0028] An electrolytic capacitor according to one embodiment of this application includes: a first electrode, a second electrode, a container for housing the first electrode and the second electrode, and a sealing member for sealing the opening of the container. The first electrode and the second electrode are constituent elements of a capacitor element. The first electrode and the second electrode may form a wound body. In the wound body, a spacer may be sandwiched between the first electrode and the second electrode. The wound body may contain a solid electrolyte.

[0029] The container can be a bottomed housing for housing capacitor elements. The bottomed housing has an opening. The bottomed housing has a cylindrical portion and a bottom surface that closes one end of the cylindrical portion. The other end of the cylindrical portion (the open end) is closed by a sealing member. The bottomed housing is, for example, cylindrical or substantially cylindrical in shape. Materials that can be used for the bottomed housing include aluminum, aluminum alloys, stainless steel, copper, iron, brass, and other metals.

[0030] The sealing component can be a sealing plate. The sealing component closes the opening of the bottom outer shell. The sealing component may have one or more insertion holes for inserting external leads. The sealing component can be made of any insulating material, but preferably includes a rubber component. The rubber component is elastic. Therefore, damage to both the external lead and the sealing component is suppressed when the external lead is inserted into the sealing component. The International Rubber Hardness (IRHD) of the rubber component is, for example, 70 or higher and 99 or lower, or 80 or higher and 95 or lower.

[0031] Examples of elastic polymers constituting rubber components include silicone rubber, fluorinated rubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber (Hypalon rubber, etc.), butyl rubber, isoprene rubber, and isobutyl-isoprene rubber. Among these, fluorinated rubber is preferred from the perspective of heat resistance.

[0032] The first electrode and the second electrode can be electrodes with different polarities. One of the first electrode and the second electrode can be an anode component with a dielectric film formed on its surface, and the other can be a cathode component. If the first electrode is an anode component (cathode component), then the second electrode is a cathode component (anode component).

[0033] The first electrode functions as an anode component, for example. In this case, the first electrode may have a first electrode foil (anode foil) comprising at least one valve-acting metal such as titanium, tantalum, aluminum, or niobium. The thickness of the anode foil is, for example, 15 μm or more and 300 μm or less.

[0034] The surface of the anode foil can be roughened using etching or similar methods. A dielectric film can be formed on the surface of the anode foil. This dielectric film can be formed, for example, by performing a formation process on the first electrode. In this case, the dielectric film may contain an oxide of the valve-acting metal. It should be noted that the dielectric film is not limited to this; any film that functions as a dielectric is acceptable.

[0035] The second electrode functions as a cathode component, for example. In this case, the second electrode may have a second electrode foil (cathode foil). The cathode foil may use the same valve-acting metal as the first electrode foil, or it may use metals such as iron (Fe) or copper (Cu). The thickness of the cathode foil is, for example, 15 μm or more and 300 μm or less.

[0036] The surface of the cathode foil can be roughened or chemically treated as needed. Additionally, an inorganic layer containing carbon, nickel, titanium, and their oxides or nitrides can be formed on the surface of the cathode foil.

[0037] The first electrode has a first electrode foil, two or more first internal leads connected to the first electrode foil, and two or more first external leads connected to the two or more first internal leads. Similarly, the second electrode may have a second electrode foil, two or more second internal leads connected to the second electrode foil, and two or more second external leads connected to the two or more second internal leads. Hereinafter, the first internal leads and the second internal leads are sometimes collectively referred to as "internal leads". In addition, the first external leads and the second external leads are sometimes collectively referred to as "external leads".

[0038] The internal leads are in foil form. The internal leads have a thickness of, for example, 15 μm or more but less than 300 μm. The materials used for the internal leads can be, for example, aluminum, titanium, nickel, copper, iron, tantalum, niobium, or alloys thereof.

[0039] External leads are used to bring the electrodes to the outside. The external leads can be rod-shaped and have enough rigidity to penetrate to the sealing component. The external leads can be made of materials such as aluminum, titanium, nickel, copper, iron, tantalum, niobium, or alloys thereof. The material of the connection portion between the internal and external leads is preferably the same.

[0040] A portion of each of two or more first internal leads is overlapped to form a stacked portion (first stacked portion). Similarly, a portion of each of two or more second internal leads may be overlapped to form a stacked portion (second stacked portion). Hereinafter, the first stacked portion and the second stacked portion are sometimes referred to collectively as "stacked portion".

[0041] The outer lead has a first part, a second part that is continuous with the first part, and a third part that is continuous with the second part. However, since the first part is continuous with the second part and the third part, there are no clear boundaries between the parts.

[0042] The first portion of the external lead has a top that is crimped to the first surface of the first laminate. The second portion of the external lead penetrates the laminate. The third portion of the external lead protrudes from the second surface of the laminate, opposite to the first surface, and penetrates the sealing member. The second portion of the external lead contacts the inner circumferential surface of the laminate.

[0043] On the inner circumferential surface of the laminated portion, preferably, the inner circumferential surfaces of two or more internal leads are offset from the second surface side towards the first surface side. This structure is very effective in significantly reducing the connection resistance between the internal leads and the external leads. When the external lead penetrates the laminated portion, a large frictional resistance is generated between the inner circumferential surfaces of the internal leads and the outer circumferential surfaces of the external leads (in other words, the outer circumferential surfaces of the second portion), thereby forming the above-described structure. In other words, the above-described structure means that electrical connection is ensured by the sufficient engagement between the inner circumferential surfaces of the internal leads and the outer circumferential surfaces of the second portion of the external leads.

[0044] The inner peripheral surface of the internal lead (hereinafter also referred to as "internal lead (1)") located closest to the first surface of the laminated portion preferably protrudes from the second surface to the first surface and is folded back to the first surface. This structure is very effective in sufficiently reducing the connection resistance between the internal lead and the external lead. When the external lead passes through the laminated portion, at least the inner peripheral surface of the internal lead (1) protrudes from the second surface to the first surface, and then the protruding portion is folded back and pressed against the first surface, thereby forming the above structure. In other words, the above structure means that electrical connection is ensured by sufficient engagement between the internal lead (1) and the third portion of the external lead. The distance from the crease on the inner side when folded back to the furthest position of the folded-back portion is preferably 100 μm or more, more preferably 500 μm or more.

[0045] The described structure also improves conductivity by increasing the density of the connection between the laminate and the external leads. The thinner the laminate (in other words, the internal leads), the more difficult it is to ensure density. On the other hand, the requirements for electrolytic capacitors are becoming increasingly stringent, with a trend towards miniaturization and increased tolerance for ripple current. In this case, using thin internal leads and improving the density of the connection between the laminate and the external leads may become very important.

[0046] Regarding the thickness of each internal lead, considering the requirement for miniaturization of electrolytic capacitors, it is preferably 0.2 mm or less, and more preferably 0.15 mm or less.

[0047] Based on the above, the total thickness Tx of the first and second parts of the external lead can be, for example, less than 2.0 mm.

[0048] From the viewpoint of greatly improving the compactness of the connection between the laminate and the external lead, the maximum height of the first portion of the external lead relative to the first surface is preferably 0.5 mm or less, and may also be 0.3 mm or less, 0.2 mm or less, or 0.1 mm or less. In other words, in appearance, the connection between the laminate and the external lead is preferably substantially coplanar with the surrounding laminate.

[0049] From the viewpoint of greatly improving the compactness of the connection between the laminate and the external lead, the maximum diameter of the first part of the external lead as observed from the first surface side (i.e., the maximum diameter of the top of the first surface of the laminate) can be set to more than 110% of the maximum diameter of the third part (the columnar part excluding the flange). In this case, it can be said that the volume of the first part deformed by the clamping process is sufficiently ensured. Therefore, it is easy to achieve a state in which the first part deforms significantly and is fully engaged with the internal lead (1), and the inner circumferential surface of the first laminate is engaged with the second part without gap.

[0050] It should be noted that the total thickness Ty of two or more internal leads can be more than 10% and less than 90% of Tx. The total thickness Ty can be referred to as the total thickness before deformation to connect the laminate to the external leads.

[0051] The external lead may have a flange portion that contacts the second surface at the location where the third part is continuous with the second part. This flange portion acts to apply compressive stress to the connection portion when connecting the laminate to the external lead. Specifically, the edge portion of the laminate that is continuous with the inner circumferential surface is clamped between the flange portion of the third part of the external lead and the flange portion at the top formed by the deformation of the first part and is compressed.

[0052] The flange portion may have multiple protrusions or irregularities at the location where it contacts the second surface. This increases the contact area between the flange portion and the second surface, making it easier to reduce the connection resistance, and also improves the strength of the connection due to the fixation effect. Therefore, the ESR can be stabilized over a long period.

[0053] In one embodiment of the electrolytic capacitor of this application, a conductive polymer may be attached to at least one of the first electrode foil and the second electrode foil. The conductive polymer constitutes a solid electrolyte layer. When the first electrode is an anode component and the second electrode is a cathode component, the first electrode foil is an anode foil with a dielectric film formed on its surface. In this case, the solid electrolyte layer is sandwiched between the anode component and the cathode component while covering at least a portion of the dielectric film. A spacer may also be disposed between the anode component and the cathode component. This structure can sufficiently reduce the ESR of the capacitor element, and therefore can significantly improve the allowable value of ripple current. On the other hand, the more the allowable value of ripple current is improved, the more important it is to sufficiently reduce the connection resistance between the internal leads and the external leads using the configuration of this application. This is because, when significantly improving the allowable value of ripple current, it is required to suppress the heat generated by the connection resistance between the internal leads and the external leads.

[0054] There are no particular limitations on the spacer material, as long as it is porous. Examples of spacers include nonwoven fabrics made of cellulose fibers, nonwoven fabrics made of glass fibers, microporous membranes made of polyolefins, woven fabrics, and nonwoven fabrics. The thickness of the spacer is, for example, 10 μm or more and 500 μm or less.

[0055] For example, π-conjugated polymers can be used as conductive polymers. Examples of π-conjugated polymers include polypyrrole, polythiophene, polyfuran, polyaniline, and their derivatives. Derivatives refer to polymers with polypyrrole, polythiophene, polyfuran, polyaniline, etc., as their basic backbone. For example, polythiophene derivatives include poly(3,4-ethylenedioxythiophene) (PEDOT). They can be used alone, in combination of two or more monomers, or as copolymers of two or more monomers. The weight-average molecular weight of conductive polymers is not particularly limited, but can range from 1,000 to 100,000.

[0056] The solid electrolyte layer may contain π-conjugated polymers and dopants. From the viewpoint of suppressing dopant dedoping from the conductive polymer, it is desirable for the solid electrolyte layer to contain polymeric dopants. Examples of polymeric dopants include anions of polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic acid sulfonic acid, polymethacrylic acid sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and polyacrylic acid. They can be used alone or in combination of two or more monomers. Furthermore, they can be homopolymers or copolymers of two or more monomers. Polystyrene sulfonic acid (PSS) is preferred. The weight-average molecular weight of the polymeric dopants is not particularly limited; however, from the perspective of facilitating the formation of a uniform solid electrolyte layer, a weight-average molecular weight of 1,000 to 500,000 is preferred.

[0057] A solid electrolyte layer can be formed by impregnating at least one of the first electrode foil and the second electrode foil with a prescribed treatment solution. The treatment solution can be a solution in which a conductive polymer is dissolved in a solvent, or a dispersion in which a conductive polymer is dispersed in a solvent (dispersion medium). Subsequently, the solvent is evaporated from the conductive polymer adhering to at least one of the first electrode foil and the second electrode foil.

[0058] The concentration of the conductive polymer in the treatment solution is preferably 0.5 to 10% by mass, for example. Furthermore, the average particle size D50 of the conductive polymer is preferably 0.01 to 0.5 μm, for example. Here, the average particle size D50 is the median diameter in the volumetric particle size distribution determined using a particle size distribution measuring device based on dynamic light scattering.

[0059] The processing solution can be obtained, for example, by dispersing a conductive polymer in a solvent, or by polymerizing a precursor monomer in a solvent to generate conductive polymer particles. A preferred processing solution is, for example, poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate (PSS), i.e., PEDOT / PSS.

[0060] The solvent can be at least one of water and a non-aqueous solvent. The non-aqueous solvent can be a protic solvent or an aprotic solvent. Considering the stable dispersibility of conductive polymers, the solvent can contain more than 50% by mass of water.

[0061] At least one of the first and second electrode foils may be impregnated with a liquid component. In this case, the electrolytic capacitor is a solid-liquid hybrid electrolytic capacitor. Solid-liquid hybrid electrolytic capacitors readily achieve low ESR due to the solid electrolyte layer, and the liquid component effectively repairs the dielectric film of the anode foil, making them suitable for applications requiring large current flows. In other words, it is desirable for the solid-liquid hybrid electrolytic capacitor to have the largest possible allowable ripple current. The effect of reducing ESR due to decreased connection resistance greatly contributes to increasing the allowable ripple current of the solid-liquid hybrid electrolytic capacitor. It should be noted that the reduction in ESR due to decreased connection resistance includes the suppression of heat generation resulting from the reduced ESR (especially the suppression of heat generation due to the connection resistance component).

[0062] In one embodiment of the electrolytic capacitor of this application, the permissible ripple current may be, for example, 0.3A or more, 1.0A or more, or 3.0A or more.

[0063] When a large current flows, the larger the rated capacitance of the electrolytic capacitor, the better. In one embodiment of the electrolytic capacitor of this application, the rated capacitance may be 3.3 μF or more, 10 μF or more, 47 μF or more, 560 μF or more, or 1000 μF or more.

[0064] The liquid component includes a solvent. Examples of solvents include sulfone compounds, lactone compounds, carbonate compounds, and polyols. Examples of sulfone compounds include sulfolane, dimethyl sulfoxide, and diethylene sulfoxide. Examples of lactone compounds include γ-butyrolactone and γ-valerolactone. Examples of carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and fluoroethylene carbonate (FEC). Examples of polyols include glycol compounds such as ethylene glycol (EG), diethylene glycol, triethylene glycol, propylene glycol, and polyethylene glycol (PEG); and glycerol. These can be used alone or in combination. This significantly suppresses the evaporation of the liquid component, particularly suppressing the degradation of conductive polymers during reflow soldering and the initial to mid-stages of use, thus facilitating an increase in the allowable ripple current.

[0065] The solvent may contain compounds having two or more hydroxyl groups. Examples of such compounds include polyols. The content of compounds having two or more hydroxyl groups may be 50% or more, 60% or more, or 70% or more of the total solvent.

[0066] The liquid component may further contain an acid component. In the case of an electrolytic capacitor with a conductive polymer and dopant attached, the acid component in the liquid component suppresses dopant dedoping and stabilizes the conductivity of the conductive polymer. Furthermore, even if the dopant has been dedoped from the conductive polymer, the acid component of the liquid component is re-doped at the dedoping site, thus maintaining a low ESR. Considering the improved effect of suppressing dedoping, the concentration of the acid component can be 5% by mass or more and 50% by mass or less, or 15% by mass or more and 35% by mass or less.

[0067] The liquid component may contain both an acidic and a basic component. At least a portion of the acidic component is neutralized by the basic component. Therefore, it is possible to increase the concentration of the acidic component while suppressing electrode corrosion caused by the acidic component. From the viewpoint of efficiently suppressing dedoping, the acidic component is preferably in excess of the basic component in an equivalent ratio. For example, the equivalent ratio of the acidic component to the basic component can be 1 or more and 30 or less. The concentration of the basic component contained in the liquid component can be 0.1% by mass or more and 20% by mass or less, or 3% by mass or more and 10% by mass or less.

[0068] The pH of the liquid component is preferably 4 or lower, more preferably 3.8 or lower, and even more preferably 3.6 or lower. By setting the pH of the liquid component to 4 or lower, the degradation of the conductive polymer is further suppressed. The pH is preferably 2.0 or higher.

[0069] (Manufacturing method of electrolytic capacitors)

[0070] One embodiment of the present application provides a method for manufacturing an electrolytic capacitor comprising: a first connection step, a second connection step, an insertion step, a housing step, and a sealing step.

[0071] In the first connection step, two or more first internal leads are connected to the first electrode foil. In the first connection step, two or more second internal leads may be connected to the second electrode foil.

[0072] In the second connection step, two or more first internal leads are connected to first external leads. As a result, a first electrode is obtained having a first electrode foil, two or more first internal leads connected to the first electrode foil, and first external leads connected to the two or more first internal leads. The second connection step is performed after the first connection step.

[0073] In the second connection process, two or more second internal leads may be connected to the second external leads. As a result, a second electrode is obtained having a second electrode foil, two or more second internal leads connected to the second electrode foil, and second external leads connected to the two or more second internal leads.

[0074] Two or more internal leads may each have a through-hole. In this case, the external lead has a columnar portion with a maximum diameter larger than the maximum diameter of the through-hole. The columnar portion is, for example, cylindrical, and its diameter (the maximum diameter if the cross-section is not a perfect circle) is, for example, 1 mm or more and 2.5 mm or less, or 1.5 mm or more and 2 mm or less. The diameter of the columnar portion can be, for example, 100% or more and 200% or less of the maximum diameter of the through-hole, or 110% or more and 200% or less.

[0075] The columnar portion of the external lead has a first portion including one end of the columnar portion, a second portion continuous with the first portion, and a third portion continuous with the second portion and not passing through the insertion hole during the insertion process.

[0076] In the second connection process, the columnar portion is inserted into the through hole through a stacked portion where portions of two or more internal leads are overlapped. After the first portion protrudes from the first surface of the stacked portion, the first portion is flattened toward the first surface of the stacked portion. As a result, the second portion of the columnar portion is formed to be tightly fitted to the top of the first surface and engage with the inner peripheral surface of the stacked portion.

[0077] In the second connection process, for example, a columnar portion of an external lead extending in a second direction that intersects the first direction is inserted into a through hole of an internal lead extending in the first direction.

[0078] In the insertion process, the external lead (more specifically, the third part of the external lead) is inserted into the insertion hole of the sealing component. The insertion process is performed after the second connection process.

[0079] In the insertion process, after the direction of extension of the stacked portion is aligned with the second direction and the direction of extension of the external lead is aligned with the first direction, the third part of the columnar portion can be inserted into the sealing component.

[0080] In the containment process, the first electrode and the second electrode are contained in a container (e.g., a bottomed outer shell). The first electrode and the second electrode can be formed into a wound body. The wound body can have a spacer sandwiched between the first electrode and the second electrode. The wound body can contain a solid electrolyte comprising a conductive polymer. In the containment process, the liquid component can be contained in the container together with the wound body. The containment process is performed after the insertion process.

[0081] In the sealing process, the opening of the container is sealed with a sealing component. The sealing process is performed after the containment process. Before the sealing process, a process can be performed to attach a conductive polymer to the first electrode foil and the second electrode foil. Additionally, before the sealing process, a liquid component can be allowed to permeate at least one of the first electrode foil and the second electrode foil.

[0082] Hereinafter, an embodiment of an electrolytic capacitor and a method for manufacturing the same will be described with reference to the accompanying drawings. However, this application is not limited to the following description. Hereinafter, if the first electrode is an anode component (cathode component), then the second electrode is a cathode component (anode component).

[0083] Figure 1 This is a top view schematically showing the state in which the first electrode foil 11A, connected by the first internal lead 15A via the first connection process, the second electrode foil 11B, connected by the second internal lead 15B via the first connection process, and the spacer 13 sandwiched between the first electrode foil 11A and the second electrode foil 11B are arranged in a stacking sequence. Figure 1 In this winding, two or more first internal leads 15A are connected to the first electrode foil 11A, and two or more second internal leads 15B are connected to the second electrode foil 11B. Subsequently, the first electrode foil 11A and the second electrode foil 11B are wound together with a spacer 13 between them. Typically, the spacer 13 is positioned at the outermost periphery of the winding body 10, and the winding terminals are secured using a winding fixing tape 14. The length direction of each internal lead is parallel to the winding axis direction (arrow A).

[0084] Figure 2 This is a perspective view schematically illustrating the process of connecting the inner lead 15 to the outer lead 17. A through hole 15a is formed at one end of the inner lead. The outer lead 17 includes a lead body portion 171, a columnar portion 172, and a flange portion 173. A laminated portion is formed on a part (front end) of the inner lead 15 such that the through hole 15a overlaps. The columnar portion 172 of the outer lead 17 is inserted into the through hole 15a from the second surface S2 side of the laminated portion. The portion protruding from the first surface S1 of the laminated portion is a flattened first portion 18. At this time, the direction in which the inner lead extends is the first direction (arrow A), and the direction in which the outer lead 17 extends is the second direction (arrow B). Subsequently, the first portion 18 of the outer lead 17 is pressed against the flange portion 173, flattening the first portion 18. Thus, the inner lead 15 is engaged and connected to the outer lead 17. The lead body 171 is made of nickel, copper, iron, or their alloys, and its surface can be electroplated. The columnar portion 172 and the flange portion 173 are preferably made of valve-acting metals such as aluminum, titanium, tantalum, niobium, or their alloys. Considering the tightness with the internal lead 15, aluminum is the most preferred material.

[0085] Figure 3 This is a schematic cross-sectional view illustrating the second connection process of connecting the internal lead 15 to the external lead 17. Figure 3 Image (a) shows a stacked portion in which portions of the two inner leads 15 are overlapped, and a columnar portion 172 through which an outer lead 17 is inserted in a through hole 15a arranged in a connected manner. The columnar portion 172 is cylindrical, and the through hole 15a is circular. The diameter of the columnar portion 172 is larger than the diameter of the through hole 15a, being 100% or more and 200% or less, or 110% or more and 200% or less, of the diameter of the through hole.

[0086] like Figure 3 As shown in (a), a portion of the inner peripheral surface of the through hole 15a that defines the laminate or internal lead 15 undergoes plastic deformation in a manner that enlarges the diameter of the through hole 15a while being lifted by the columnar portion 172. Therefore, the inner peripheral surface of the through hole 15a shifts position from the second surface S2 side to the first surface S1 side. Furthermore, at least in the internal lead 15 disposed closest to the first surface S1 side, the vicinity of the inner peripheral surface of the through hole 15a protrudes from the second surface S2 side to the first surface S1 side.

[0087] Subsequently, the first portion 18 protruding from the first surface S1 of the laminated portion is flattened towards the first surface S1 of the laminated portion. At this time, as... Figure 3 As shown in (c), the inner peripheral surface of the inner lead 15 protruding toward the first surface S1 is folded back to the first surface S1.

[0088] During the deformation of the first part 18, the first part 18 becomes a top 181 with a flange portion, and the area near the inner circumferential surface of the laminated portion sandwiched between the top 181 and the flange portion 173 is compressed. In this way, the top 181 is hemmed into the first surface S1, and the second portion 182 of the columnar portion 172 engages with the inner circumferential surface of the laminated portion. When the flattening of the first part 18 is complete, the columnar portion 172 of the outer lead 17 becomes the top 181, the second portion 182 penetrating the laminated portion, and the third portion 183 protruding from the second surface of the laminated portion. The second portion 182 becomes in a state of close contact with the inner circumferential surface of the laminated portion.

[0089] Figure 3 Example (d) shows the total thickness Tx of the first and second portions of the external lead. Tx can be, for example, 2.0 mm or less. In addition, the total thickness Ty of two or more internal leads is, for example, more than 10% and less than 90% of Tx.

[0090] Figure 4 This is a side view of a wound body 10 having a first connecting portion 16A to which a first external lead 17A is connected in the first internal lead 15A and a second connecting portion 16B to which a second external lead 17B is connected in the second internal lead 15B.

[0091] Figure 5 This is a side view of the wound body 10 after the insertion process.

[0092] Figure 6 This is a side view of the completed electrolytic capacitor 100 with its bottom casing 60 and sealing component 20 in cross-section.

[0093] It should be noted that the insertion process, as described above, is performed after the direction in which the laminated portions (i.e., the first connecting portion 16A and the second connecting portion 16B) extend is aligned with the second direction (arrow B) and the direction in which the first external lead 17A and the second external lead 17B extend is aligned with the first direction (arrow A).

[0094] Figure 7 This is a partial schematic diagram of the side of the outer lead 17, showing the variation of the flange. Figure 7 In (a), a plurality of sharp protrusions 173a are provided on the surface of the flange portion 173 opposite to the second surface S2 of the laminated portion. As a variation thereof... Figure 7 In (b), a plurality of spherical protrusions 173b are provided on the surface opposite to the second surface S2 of the laminated portion of the flange portion 173. Figure 7 In (c), multiple protruding flange portions 173A are shown on the surface opposite to the second surface S2 of the laminate. These flange portions all play a role in reducing the connection resistance between the external lead and the internal lead and in significantly improving the allowable value of ripple current.

[0095] Figure 8 This is a schematic cross-sectional view illustrating another example of the second connection process where the internal lead connects to the external lead, and is taken with reference to... Figure 3 A variation of the second connection process described herein. Here, washer 19 is used. Washer 19 is disposed on the first surface S1 of the laminated portion in such a way that it surrounds the edge of the through hole 15a. Figure 8 As shown in (a), a portion of the inner peripheral surface of the through hole 15a that defines the laminate or internal lead 15 undergoes plastic deformation in a manner that enlarges the diameter of the through hole 15a while being lifted by the columnar portion 172. Furthermore, at least in the internal lead 15 disposed closest to the first surface S1, the area near the inner peripheral surface of the through hole 15a protrudes from the second surface S2 side toward the first surface S1 side.

[0096] Subsequently, the first portion 18 protruding from the first surface S1 of the laminated portion is flattened towards the first surface S1 of the laminated portion. At this time, as... Figure 8 As shown in (c), the inner circumferential surface of the internal lead 15 protruding towards the first surface S1 is folded back to the first surface S1 by a washer 19. By using the washer 19, the compressive stress near the inner circumferential surface of the laminated portion during the deformation of the first part 18 is significantly increased. Figure 8 As shown in (d), when the flattening of the first part 18 ends and the top 181 formed by the deformation of the first part 18, the second part 182 that penetrates the laminate, and the third part 183 that protrudes from the second surface of the laminate are formed, the second part 182 becomes a state of highly dense contact with the inner periphery of the laminate.

[0097] Industrial availability

[0098] This application can be used for electrolytic capacitors. It is particularly suitable for electrolytic capacitors used in applications requiring low ESR and tolerating increased ripple current (e.g., solid-liquid hybrid electrolytic capacitors).

[0099] While the invention has been described with respect to preferred embodiments, this disclosure should not be interpreted as restrictive. Various modifications and alterations will be readily apparent to those skilled in the art upon reading the foregoing disclosure. Therefore, the scope of the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

[0100] Explanation of reference numerals in the attached figures

[0101] 100 Electrolytic capacitor, 10 Winding body, 11A First electrode foil, 11B Second electrode foil, 13 Spacer, 14 Winding and fixing tape, 15A First internal lead, 15B Second internal lead, 15a Through hole, 16A First connecting part, 16B Second connecting part, 17A First external lead, 17B Second external lead, 171 Lead body part, 172 Columnar part, 173, 173A Flange part, 173a, 173b Protrusion part, 18 First part, 181 Top, 182 Second part, 183 Third part, 20 Sealing component, 60 Bottomed outer casing.

Claims

1. An electrolytic capacitor comprising: First electrode, Second electrode, The container housing the first electrode and the second electrode, and A sealing component that blocks the opening of the container. The first electrode has a first electrode foil, two or more first internal leads connected to the first electrode foil, and a first external lead connected to the two or more first internal leads. A portion of each of the two or more first internal leads is overlapped to form a stacked portion. The first external lead has a first portion, a second portion continuous with the first portion, and a third portion continuous with the second portion. The first part has a top that is hemmed into the first surface of the laminated portion. The second part extends through the stacked portion. The third part protrudes from the second surface of the laminate, which is opposite to the first surface, and penetrates the sealing member. The second part is in contact with the inner peripheral surface of the laminated portion.

2. The electrolytic capacitor according to claim 1, wherein, On the inner peripheral surface of the stacked portion, the inner peripheral surfaces of each of the two or more first internal leads are offset from the second surface side toward the first surface side.

3. The electrolytic capacitor according to claim 2, wherein, The inner peripheral surface of the stacked portion, located near the first internal lead closest to the first surface, protrudes from the second surface towards the first surface and is folded back to the first surface.

4. The electrolytic capacitor according to claim 1, wherein, The total thickness Tx of the first portion and the second portion of the first external lead is less than 2 mm.

5. The electrolytic capacitor according to claim 1, wherein, The maximum height of the first portion of the first external lead relative to the first surface is less than 0.5 mm.

6. The electrolytic capacitor according to claim 1, wherein, The maximum diameter of the first portion of the first external lead, when viewed from the first face side, is more than 110% of the maximum diameter of the third portion.

7. The electrolytic capacitor according to claim 1, wherein, The total thickness Ty of the two or more first internal leads is more than 10% and less than 90% of Tx.

8. The electrolytic capacitor according to claim 1, wherein, The portion of the third part that is continuous with the second part has a flange portion that contacts the second surface.

9. The electrolytic capacitor according to claim 8, wherein, The flange portion has multiple protrusions or irregularities at the position where it contacts the second surface.

10. The electrolytic capacitor according to claim 1, wherein, A conductive polymer is attached to the first electrode foil.

11. The electrolytic capacitor according to claim 1, wherein, The first electrode foil is impregnated with liquid components.

12. The electrolytic capacitor according to claim 1, wherein the permissible ripple current is 0.3A or more.

13. The electrolytic capacitor according to claim 1, wherein the rated capacitance is 3.3 μF or higher.

14. A method for manufacturing an electrolytic capacitor, the method comprising: The first connection process in which two or more first internal leads are connected to the first electrode foil; After the first connection step, the two or more first internal leads are connected to the first external leads to obtain the second connection step of the first electrode; After the second connection step, the insertion step is performed to insert the first external lead into the insertion hole of the sealing component; Following the insertion process, a receiving process is performed to house the first electrode and the second electrode in a container; and Following the receiving process, a sealing process is performed where the sealing component is used to seal the opening of the container. Each of the two or more first internal leads has a through hole. The first external lead has a columnar portion, and the columnar portion has a maximum diameter larger than the maximum diameter of the through hole. The columnar portion has a first portion including one end of the columnar portion, a second portion continuous with the first portion, and a third portion continuous with the second portion and not passing through the insertion hole during the insertion process. In the second connection process, the columnar portion is inserted into the through hole by the overlapping portion of each of the two or more first internal leads, so that the first portion protrudes from the first surface of the overlapping portion, and the first portion is flattened toward the first surface of the overlapping portion. While forming a top that is tightly fitted to the first surface, the second portion is engaged with the inner peripheral surface of the overlapping portion.

15. The method for manufacturing an electrolytic capacitor according to claim 14, wherein, In the second connection step, the columnar portion of the first external lead extending along a second direction that intersects the first direction is inserted into the through hole of the first internal lead extending along the first direction.

16. The method for manufacturing an electrolytic capacitor according to claim 14, wherein, In the insertion process, after aligning the direction of the stacked portion along the second direction and the direction of the first external lead along the first direction, the third portion of the columnar portion is inserted into the sealing component.

17. The method for manufacturing an electrolytic capacitor according to claim 14, wherein, Prior to the sealing process, there is a process of attaching a conductive polymer to the first electrode foil.

18. The method for manufacturing an electrolytic capacitor according to claim 14, wherein, Prior to the sealing process, there is a process of permeating the first electrode foil with liquid components.

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