Electrolytic capacitor and method of manufacturing electrolytic capacitor

Abstract

The multilayer element of the electrolytic capacitor includes a capacitor element and an anode lead (31) electrically connected to an anode foil (22). The capacitor element has an anode foil (22) comprising a metal portion and a dielectric layer, and a cathode foil opposite to the anode foil (22) separated by a separator. The anode foil (22) has an anode body and an anode lead (22b). The cathode foil is opposite to the dielectric layer of the anode body. A portion of the anode lead (31) overlaps with the anode lead (22b). A plurality of joints (J1) are formed in the overlapping region (R1) between the anode lead (22b) and the anode lead (31), which join the anode lead (31) to the metal portion. Two adjacent joints (J1) are connected via the metal portion. In the portion outside the plurality of joints (J1) in the overlapping region (R1), a dielectric layer is sandwiched between the anode lead (31) and the metal portion.

Description

[0001] Cross-reference to related applications

[0002] This disclosure claims the benefit of priority to Japanese Patent Application No. 2023-213289, filed on December 18, 2023, with the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to electrolytic capacitors and methods for manufacturing electrolytic capacitors. Background Technology

[0004] Conventionally, stacked electrolytic capacitors are known, comprising multiple anode foils and multiple cathode foils stacked with a separator between them (e.g., Patent Document 1). In the electrolytic capacitor of Patent Document 1, anode foils and cathode foils having oxide coating layers are stacked sequentially with a separator between them. In one embodiment of this electrolytic capacitor, the protrusions (lead-out portions) of the anode foil are formed by a single foil integral with the anode foil, and after the oxide coating layer of the protrusions is removed using a laser, the multiple protrusions are interconnected by friction stir welding or the like.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2005-45078 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, in the electrolytic capacitor of Patent Document 1, the solder joint is larger, and the area for connecting multiple anode foils to each other is larger, thus reducing the proportion of the area in the electrolytic capacitor that contributes to capacitance (the area where the anode foil and cathode foil face each other). Furthermore, a process to remove the oxide film layer before soldering is required, potentially increasing manufacturing costs. Additionally, a process is needed to connect the anode leads for external connections to the anode foils. In this context, the present disclosure provides an electrolytic capacitor having a joint that can securely bond the anode foils to each other with low resistance in a smaller area.

[0010] Methods for solving problems

[0011] One aspect of this disclosure relates to an electrolytic capacitor. The electrolytic capacitor includes a stacked element comprising: at least one capacitor element having an anode foil and a cathode foil, the anode foil comprising a metal portion and a dielectric layer formed on the surface of the metal portion, the cathode foil being opposite the anode foil via a separator; an anode lead electrically connected to the anode foil; and a cathode lead electrically connected to the cathode foil, the anode foil having an anode body and an anode lead-out portion, the cathode foil being opposite the dielectric layer formed on the anode body, a portion of the anode lead-out portion overlapping the anode lead-out portion, a plurality of joints being formed in the overlapping region of the anode lead-out portion and the anode lead-out portion, the plurality of joints joining the anode lead-out portion to the metal portion of the anode foil, two adjacent joints of the plurality of joints being connected via the metal portion of the anode foil, and the dielectric layer being sandwiched between the anode lead-out portion and the metal portion of the anode foil in the portion outside the plurality of joints in the overlapping region.

[0012] Another aspect of this disclosure relates to a method for manufacturing an electrolytic capacitor. The method includes: a first step of preparing an anode foil having a metal portion and a dielectric layer formed on the surface of the metal portion; a second step of laminating a cathode foil over at least a portion of the dielectric layer with a separator, thereby forming at least one capacitor element; and a third step of overlapping anode leads on an anode lead portion of the anode foil that is not opposite to the cathode foil, and irradiating the anode leads with a laser, thereby joining the anode leads to the metal portion of the anode foil to form a plurality of joints.

[0013] Invention Effects

[0014] According to this disclosure, an electrolytic capacitor with low resistance and a robust joint can be obtained.

[0015] The novel features of the invention are set forth in the appended claims; however, the invention should be more fully understood, in both its structure and content, together with its other objects and features, by referring to the following detailed description of the accompanying drawings. Attached Figure Description

[0016] Figure 1 This is a perspective view schematically showing the stacked elements of the first embodiment.

[0017] Figure 2 It has Figure 1 A top view of an electrolytic capacitor with stacked components.

[0018] Figure 3 It is a cross section passing through multiple joints (along) Figure 2A cross-sectional view of the anode lead and anode lead-out section of the III-III line is shown in the lower left corner, with a portion enlarged.

[0019] Figure 4 This is a perspective view schematically showing the anode lead and anode lead in the stacked element of the second embodiment. Detailed Implementation

[0020] The following description illustrates embodiments of the electrolytic capacitor and its manufacturing method according to the present disclosure. However, the present disclosure is not limited to the examples described below. Specific values ​​and materials are sometimes illustrated in the following description, but other values ​​and materials may be applied as long as the effects of the present disclosure are achieved.

[0021] (Electrolytic capacitor)

[0022] The electrolytic capacitor disclosed herein is a laminated electrolytic capacitor comprising an anode foil and a cathode foil laminated together with a separator. The electrolytic capacitor of this disclosure comprises a laminated element. The laminated element comprises at least one capacitor element, an anode lead, and a cathode lead. The laminated element may also comprise multiple capacitor elements. The laminated element, along with a portion of the anode lead and cathode lead, is housed together with the electrolyte in a casing.

[0023] A capacitor element has an anode foil and a cathode foil. The anode foil includes a metal portion and a dielectric layer formed on the surface of the metal portion. The cathode foil is opposite to the anode foil via a separator. A solid electrolyte may be disposed between the anode foil and the cathode foil. The separator may contain a solid electrolyte. Multiple anode foils and cathode foils may be alternately stacked, with the separator sandwiched in between.

[0024] The anode foil has an anode body and an anode lead-out portion. The anode foil can be formed in sheet form. The metal portion of the anode foil typically has a porous layer formed by surface roughening such as etching, and a non-porous core portion. That is, the metal portion of the anode foil can have a core portion and a porous portion disposed outside the core portion. A dielectric layer is formed on the surface of the metal portions of the anode body and the anode lead-out portion. That is, the dielectric layer is formed along the surface of the porous portion of the metal portion. The dielectric layer is composed of an oxide of the metal constituting the metal portion. It should be noted that the dielectric layer can also be composed of an oxide of a metal other than the metal constituting the metal portion. At least a portion of the dielectric layer is covered by a solid electrolyte.

[0025] As the material for the metal part, a valve-acting metal or an alloy or compound containing a valve-acting metal can be used. Aluminum, tantalum, or niobium, etc., can be used as the valve-acting metal.

[0026] Dielectric layers can be formed, for example, by immersing a foil containing a metal portion in a chemical conversion solution such as ammonium adipate solution, and then chemically converting the foil under a voltage applied as needed. Alternatively, dielectric layers can also be formed using atomic layer deposition (ALD) or chemical vapor deposition (CVD).

[0027] Solid electrolytes may contain, for example, manganese compounds or conductive polymers. Examples of conductive polymers include polypyrrole, polythiophene, polyaniline, and their derivatives. Solid electrolytes containing conductive polymers can be formed, for example, by chemically polymerizing and / or electrolytically polymerizing raw material monomers on a dielectric layer. Alternatively, solid electrolytes can be formed, for example, by attaching a solution containing dissolved conductive polymers or a dispersion of conductive polymers to a dielectric layer.

[0028] The cathode foil is positioned opposite the dielectric layer of the anode body formed on the anode foil, separated by a separator. In the region where the anode and cathode foils face each other, the capacitance of the electrolytic capacitor is realized. The cathode foil can be made of metal foil. The aforementioned valve-acting metal can be used as the material for the metal foil. The surface of the cathode foil can be roughened. An oxide film can be formed on the surface of the cathode foil as needed. A conductive layer, such as a carbon layer, can be formed on the surface of the cathode foil as needed.

[0029] A diaphragm is sandwiched between the anode foil and the cathode foil. Non-woven fabric can be used as the diaphragm. The fiber material constituting the non-woven fabric can be cellulose, polyethylene terephthalate, vinylon, polyamides (aliphatic polyamides, aromatic polyamides, etc.), etc. The diaphragm can be impregnated with electrolyte.

[0030] The electrolyte can be a mixture of a non-aqueous solvent and an ionic substance (solute, such as an organic salt) dissolved therein. The non-aqueous solvent can be an organic solvent or an ionic liquid. Examples of non-aqueous solvents include ethylene glycol, propylene glycol, sulfolane, γ-butyrolactone, and N-methylacetamide. Examples of organic salts include trimethylamine maleate, triethylamine borosalicylate, dimethylethylamine phthalate, mono-1,2,3,4-tetramethylimidazoline phthalate, and mono-1,3-dimethyl-2-ethylimidazoline phthalate. It should be noted that the electrolyte can be a liquid at room temperature (25°C) or at the temperature at which the electrolytic capacitor is used.

[0031] The anode lead is electrically connected to the anode foil. The anode lead is made of metal (e.g., aluminum, aluminum alloy, gold, silver, copper, platinum, etc.). Alternatively, a plating layer containing nickel, gold, copper, or tin may be formed on the surface of the anode lead. The material of the anode lead can be the same as the material of the cathode foil. In this case, a good electrical connection between the anode lead and the anode foil can be achieved. The anode lead functions as the first external terminal of the electrolytic capacitor.

[0032] The cathode lead is electrically connected to the cathode foil. The cathode lead is made of metal (e.g., aluminum, aluminum alloy, gold, silver, copper, platinum, etc.). Alternatively, a plating layer containing nickel, gold, copper, or tin may be formed on the surface of the cathode lead. The material of the cathode lead can be the same as the material of the cathode foil. In this case, a good electrical connection between the cathode lead and the cathode foil can be achieved. The cathode lead functions as the second external terminal of the electrolytic capacitor.

[0033] A portion of the anode lead overlaps with the anode lead-out portion of the anode foil. Multiple joints are formed in the overlapping area of ​​the anode lead-out portion and the anode lead (the area where the anode lead-out portion and the anode lead overlap when viewed from the stacking direction of the capacitor element), and these multiple joints connect the anode lead-out portion to the metal portion of the anode foil. When viewed from the stacking direction of the capacitor element, the multiple joints can each be formed as a dot. When viewed from this stacking direction, the multiple joints can be arranged in a straight line or in an alternating pattern. Alternatively, the multiple joints can form a dotted joint area composed of a collection of dotted joints, and multiple such dotted joint areas can exist. Each of the multiple joints is columnar, connecting the upper surface of the anode lead-out portion to the lower surface of the anode foil (the lower surface of the lowest anode foil in the case of multiple anode foils being joined). Two adjacent joints in the multiple joints are connected via the metal portion of the anode foil. Outside of the multiple joints in the overlapping area, a dielectric layer is sandwiched between the anode lead-out portion and the metal portion of the anode foil.

[0034] By arranging multiple joints, the size of a single joint can be reduced, thus shrinking the area that does not contribute to the capacitance of the electrolytic capacitor. Furthermore, the anode lead and anode foil are bonded with low resistance and robustly in the stacking direction of the capacitor element. The main reason for achieving low-resistance bonding is the presence of multiple joints, which sufficiently ensures the area of ​​the current path in the stacking direction. In addition to the robust bonding achieved by the presence of multiple joints, adjacent two joints are connected via the metal portion of the anode foil. Therefore, robust bonding can also be achieved in a direction orthogonal to the stacking direction (hereinafter, simply referred to as the orthogonal direction). When this bonding structure is observed using a cross-section passing through the multiple joints, it becomes a lattice-like bonding structure extending in both the stacking direction and the orthogonal direction (hereinafter, simply referred to as the lattice structure). The lattice structure is more robust than a bonding structure in which multiple joints are formed individually (i.e., a bonding structure without orthogonal connections). As described above, the electrolytic capacitor of this disclosure possesses low-resistance and robust joints (or bonding structures).

[0035] In the overlapping region, the ratio (T1 / T2) of the total thickness T1 of the anode foil and anode leads at each of the multiple joints to the total thickness T2 of the anode foil and anode leads in the portion excluding the multiple joints can be 0.7 or more and 1.2 or less. In this configuration, there is no significant difference in the total thickness of the anode foil and anode leads between the joints and their surrounding portions. That is, the thickness of the anode foil does not change much during the formation of the joints, or the anode foil does not deform significantly. Therefore, the anode foil is less prone to defects such as cracks, and the electrode structure based on multiple joints can be stabilized. It should be noted that the total thicknesses T1 and T2 can be obtained by measuring the total thickness at any number of points in the region and taking it as the average value.

[0036] The metal portion of the anode foil can have a core and a porous portion disposed outside the core. The maximum width of each of the multiple joints can be greater than the thickness of the core of the metal portion of the anode foil. In this configuration, the path of current flowing through the multiple joints in the stacking direction (or the area of ​​each of the multiple joints) is large, thus further reducing the resistance at the joints. It should be noted that the maximum width of the joint refers to the maximum dimension of each joint in the orthogonal direction in the cross-section passing through the multiple joints. In addition, the thickness of the core of the metal portion (i.e., the length dimension of the core of the metal portion in the stacking direction) can be obtained by measuring the thickness of the core of the metal portion at any multiple locations and taking it as its average value. The maximum width of the joint and the thickness of the core of the metal portion can be determined, for example, based on scanning electron microscope (SEM) images of the cross-section passing through the multiple joints.

[0037] The shortest distance between two adjacent joints can be greater than 0 μm and less than 300 μm. In this configuration, by arranging adjacent joints close to each other, multiple joints can be formed in a defined area, thereby reducing the connection resistance between the anode lead and the anode foil. This shortest distance can be greater than 0 μm and less than 200 μm, or it can be greater than 50 μm and less than 150 μm.

[0038] The maximum width of each of the multiple junctions can be 100 μm or less. In this configuration, by reducing the width of the junctions, the area that does not contribute to the capacitance of the electrolytic capacitor can be reduced. Furthermore, deformation of the anode foil (and anode leads) before and after the formation of the junctions can be suppressed, thereby stabilizing the electrode structure. It should be noted that this maximum width can be 90 μm or less, or 80 μm or less. Alternatively, this maximum width can be greater than 0 μm.

[0039] In the overlapping region, through holes extending along the thickness direction of the anode foil may not be present at locations where multiple joints are in contact. By eliminating through holes, unnecessary areas for electrical connection between the anode lead and the anode foil can be reduced.

[0040] The proportion of insulating material constituting the dielectric layer in multiple joints can be 0% or more and 20% or less by volume. Because the proportion of this insulating material (e.g., oxides of valve-acting metals contained in the metal portion) is small, the resistance in each joint can be reduced, thereby reducing the equivalent series resistance (ESR) of the electrolytic capacitor. This proportion can be 0% or more and 10% or less by volume, or 0% or more and 5% or less by volume.

[0041] At least one capacitor element can be composed of multiple capacitor elements stacked on top of each other and including adjacent first and second capacitor elements. Preferably, the anode leads of the anode foil of the first capacitor element and the anode leads of the anode foil of the second capacitor element are joined together at multiple joints. Near each of these joints, the spacing between the anode leads of the anode foils of the first and second capacitor elements is 0% to 20% of the thickness of the anode foil. With this configuration, the anode foils of multiple capacitor elements can be reliably joined together. It should be noted that "near each of these joints" refers to a region where the distance from the outer contour line of the joint is 100 μm or less when viewed from the stacking direction.

[0042] (Manufacturing method of electrolytic capacitors)

[0043] The method for manufacturing the electrolytic capacitor disclosed herein can be used, for example, to manufacture the aforementioned electrolytic capacitor, but it can also be used to manufacture other electrolytic capacitors. The method for manufacturing the electrolytic capacitor disclosed herein includes a first step, a second step, and a third step.

[0044] In the first step, an anode foil having a metal portion and a dielectric layer formed on the surface of the metal portion is prepared. The steps of preparing the anode foil include both the step of making a new anode foil and the step of obtaining a completed anode foil.

[0045] In the second step, cathode foil is stacked in at least a portion of the dielectric layer through a diaphragm, thereby forming at least one capacitor element.

[0046] In the third step, an anode lead is overlapped on the anode lead portion of the anode foil that is not opposite to the cathode foil, and the anode lead is irradiated with a laser, thereby joining the anode lead to the metal portion of the anode foil to form multiple joints. This achieves a low-resistance and robust joint.

[0047] Before the second process, the portion of the anode foil that becomes the junction may not need to be perforated. In this case, the time required for perforation can be saved, thus reducing the manufacturing cost of the electrolytic capacitor.

[0048] Before the third step, the dielectric layer at the location where the joint will be formed may not need to be removed beforehand. In this case, in the third step, the anode lead may be irradiated with a laser to repel the dielectric layer at the joint and bond the anode lead to the metal portion of the anode foil. Typically, if the laminated anode foil is directly irradiated with a laser in a manner that repels the dielectric layer at the joint and bonds the anode lead to the metal portion of the anode foil, the metal portion of the irradiated anode foil may melt due to the laser power, sometimes preventing the successful formation of the joint. In contrast, in this application, it is proposed that by irradiating the anode lead overlapping the anode foil with a laser, the molten metal of the anode lead can enter the portion of the anode foil corresponding to the joint, allowing the joint to be formed without melting the metal portion of the anode foil. The laser can be irradiated multiple times at one location on the anode lead. For each joint, the laser can be irradiated with a gradually decreasing output power from the start of irradiation. The laser output power increases proportionally to the number of laminated anode foils, with each anode foil having a power of 30W or more and 70W or less. The laser irradiation time can also be less than 1 second for each joint.

[0049] As described above, according to this disclosure, an electrolytic capacitor with low resistance and robust joints can be obtained through a lattice-like bonding structure. Furthermore, according to this disclosure, such an electrolytic capacitor can be manufactured at low cost.

[0050] Hereinafter, an example of an electrolytic capacitor and a method for manufacturing an electrolytic capacitor according to the present disclosure will be specifically described with reference to the accompanying drawings. The constituent elements and processes of the electrolytic capacitor and the method for manufacturing an electrolytic capacitor in the example described below can be applied to the aforementioned constituent elements and processes. The constituent elements and processes of the electrolytic capacitor and the method for manufacturing an electrolytic capacitor in the example described below can be modified based on the above description. Furthermore, the matters described below can also be applied to the above embodiments. In the constituent elements and processes of the electrolytic capacitor and the method for manufacturing an electrolytic capacitor in the example described below, constituent elements and processes that are not essential to the electrolytic capacitor and the method for manufacturing an electrolytic capacitor according to the present disclosure can be omitted. It should be noted that the figures shown below are schematic diagrams and do not accurately reflect the shape and number of actual components. Additionally, in the following description, terms indicating direction such as "up" and "down" are sometimes used, but these are used for ease of explanation and do not limit the scope of the present disclosure.

[0051] Implementation Method 1

[0052] The first embodiment of this disclosure will be described. For example... Figures 1-3 As shown, the electrolytic capacitor 10 of this embodiment includes a stacked element 20 and a housing 40.

[0053] The stacked element 20 includes a plurality of capacitor elements 21, an anode lead 31, and a cathode lead 32. The plurality of capacitor elements 21 includes a first capacitor element 21 and a second capacitor element 21 that are adjacent to each other.

[0054] Each capacitor element 21 includes an anode foil 22, a cathode foil 23, and a diaphragm 24 sandwiched between them. The anode foil 22 and the cathode foil 23 are made of a valve-acting metal or an alloy or compound containing a valve-acting metal. The diaphragm 24 is made of, for example, nonwoven fabric. The diaphragm 24 contains a solid electrolyte and is impregnated with an electrolyte solution (not shown).

[0055] The anode foil 22 is in the form of a foil or sheet, and its shape is rectangular. The anode foil 22 includes a metal portion and a dielectric layer formed on the surface of the metal portion. The surface of the metal portion of the anode foil 22 is roughened, and it includes a core portion 22c and a porous portion 22d disposed outside the core portion 22c (see reference). Figure 3 A dielectric layer is formed along the surface of the porous portion 22d. The anode foil 22 has an anode body 22a and an anode lead-out portion 22b. The anode body 22a is the portion opposite to the cathode foil 23 across a diaphragm, and the anode lead-out portion 22b is the portion of the anode foil 22 other than the anode body 22a. The porous portion 22d containing the dielectric layer is formed on the surfaces of both the anode body 22a and the anode lead-out portion 22b. At least a portion of the dielectric layer is covered by a solid electrolyte.

[0056] The cathode foil 23 is foil-shaped or sheet-shaped, and has a rectangular shape. The cathode foil 23 has a cathode body 23a and a cathode lead-out portion 23b. The cathode body 23a is the portion that faces the anode foil 22 (more specifically, the anode body 22a) across a diaphragm. The cathode lead-out portion 23b is the portion of the cathode foil 23 other than the cathode body 23a. The cathode body 23a faces the dielectric layer formed on the anode body 22a. The cathode body 23a is in contact with the solid electrolyte.

[0057] Anode lead 31 is electrically connected to anode foil 22. A portion of anode lead 31 overlaps with the anode lead-out portion 22b of anode foil 22. Multiple joints J1 are formed in the overlapping area R1 of anode lead-out portion 22b and anode lead 31, which join the anode lead 31 to the metal portion of anode foil 22. The multiple joints J1 are located in the width direction of anode foil 22. Figure 1 The anode leads 31 and multiple anode leads 22b are arranged in a straight line along the Y-axis. Each joint J1 is formed to pass through the anode lead 31 and multiple anode leads 22b in the stacking direction. Two adjacent joints J1 are connected via the core 22c of the metal portion of the anode foil 22. In the overlapping region R1, excluding the multiple joints J1, a porous portion 22d containing a dielectric layer is sandwiched between the anode lead 31 and the core 22c of the metal portion of the anode foil 22. Thus, the above-described lattice structure is formed in the overlapping region R1.

[0058] The ratio (T1 / T2) of the total thickness T1 of the anode foil 22 and anode lead 31 of each of the multiple joints J1 in the overlapping region R1 to the total thickness T2 of the anode foil 22 and anode lead 31 of the portion excluding the multiple joints J1 is preferably 0.7 or more and 1.2 or less.

[0059] The maximum width W of each of the multiple joints J1 is preferably greater than the thickness T of the core portion 22c of the metal portion of the anode foil 22.

[0060] The shortest distance D between two adjacent joints J1 is preferably greater than 0 μm and less than 300 μm.

[0061] The maximum width W of each of the multiple joints J1 is preferably less than 100 μm.

[0062] In the overlapping region R1, it is preferable that there are no through holes extending along the thickness direction of the anode foil 22 at the positions that contact the multiple joints J1.

[0063] The proportion of insulating material (e.g., oxide of valve action metal) constituting the dielectric layer in the multiple joints J1 is preferably 0% or more and 20% or less by volume.

[0064] The anode lead-out portion 22b of the anode foil 22 of the first capacitor element 21 and the anode lead-out portion 22b of the anode foil 22 of the second capacitor element 21 adjacent to the first capacitor element 21 are joined together at multiple joint portions J1. Near each of the multiple joint portions J1, the spacing between the anode lead-out portion 22b of the anode foil 22 of the first capacitor element 21 and the anode lead-out portion 22b of the anode foil 22 of the second capacitor element 21 is preferably 0% or more and 20% or less of the thickness of the anode foil 22.

[0065] The cathode lead 32 is electrically connected to the cathode foil 23. A portion of the cathode lead 32 overlaps with the cathode lead-out portion 23b of the cathode foil 23. Preferably, a plurality of joint portions J2 are formed in the overlapping region R2 of the cathode lead-out portion 23b and the cathode lead 32, similar to the overlapping region R1 described above.

[0066] The housing 40 accommodates the stacked element 20. Anode lead 31 and cathode lead 32 extend from one side of the housing 40. Figure 2 The layers (below) are led out separately from each other. The laminated elements 20 can be housed together with the electrolyte in the housing 40. The housing 40 in this embodiment is made of a laminate with a metal barrier layer, but is not limited thereto. For example, the housing 40 may also be made of insulating materials such as ceramics and resins, metals such as aluminum, stainless steel, copper, iron, and brass, or alloys thereof.

[0067] (Manufacturing method of electrolytic capacitors)

[0068] The manufacturing method of the electrolytic capacitor according to this embodiment will be described. The manufacturing method includes a first step, a second step, and a third step.

[0069] In the first step, an anode foil 22 having a metal part and a dielectric layer formed on the surface of the metal part is prepared.

[0070] In the second step, cathode foil 23 is stacked over at least a portion of the dielectric layer with a diaphragm in between, thereby forming a plurality of capacitor elements 21. Here, it is preferable not to perform hole processing on the portion of anode foil 22 that becomes the junction J1 (in the third step) before the second step.

[0071] In the third step, an anode lead 31 is overlapped on the anode lead-out portion 22b of the anode foil 22 where the cathode foil 23 is not opposite, and a laser is irradiated onto the anode lead 31, thereby bonding the anode lead 31 to the metal portion of the anode foil 22 to form a plurality of joints J1. In the third step, it is preferable to irradiate the anode lead 31 with a laser in a manner that repels the dielectric layer at the joints J1 and bonds the anode lead 31 to the metal portion of the anode foil 22.

[0072] Implementation Method 2

[0073] The second embodiment of this disclosure will be described. The configuration of the anode lead 31 of the electrolytic capacitor 10 in this embodiment differs from that in the first embodiment described above. Hereinafter, the differences from the first embodiment will be mainly described.

[0074] like Figure 4 As shown, in this embodiment, a plurality of anode leads 31 (3 in this example) are provided. The plurality of anode leads 31 include a first anode lead 31A, a second anode lead 31B, and a third anode lead 31C. It should be noted that at least one of the second anode lead 31B and the third anode lead 31C may be omitted. In addition, the number of anode leads 31 is not limited to 3 and can be arbitrarily set.

[0075] The first anode lead 31A has a top wall portion 31a and a side wall portion 31b. From the stacking direction ( Figure 4 Viewed along the Z-axis, the top wall portion 31a overlaps the plurality of anode foils 22 (specifically, anode lead-out portions 22b). The side wall portion 31b is integrally formed with the top wall portion 31a to cover the ends of the plurality of anode foils 22. Figure 4 The first anode lead 31A extends along the stacking direction in a manner that extends from the left end of the lead. Figure 4 When viewed along the Y-axis, it forms an approximate L-shape. The so-called end-face collector structure can be achieved through the sidewall portion 31b.

[0076] The second anode lead 31B is disposed among a plurality of anode foils 22 (specifically, anode lead-out portions 22b) in a manner separate from the top wall portion 31a of the first anode lead 31A in the stacking direction, and contacts or approaches the side wall portion 31b of the first anode lead 31A. The shape of the second anode lead 31B may be the same as or different from the shape of the top wall portion 31a of the first anode lead 31A. It should be noted that in Figure 4 The image depicts the second anode lead 31B separated from the anode foil 22 on it in the stacking direction, but in reality, the second anode lead 31B and the anode foil 22 on it are in contact or connected to each other at least at the junction J1 (the same applies to the third anode lead 31C and the anode foil 22 on it).

[0077] The third anode lead 31C is disposed between a plurality of anode foils 22 (specifically, anode lead-out portions 22b) in a manner separate from the second anode lead 31B in the stacking direction, and contacts or approaches the sidewall portion 31b of the first anode lead 31A. The shape of the third anode lead 31C may be the same as or different from the shape of the top wall portion 31a of the first anode lead 31A.

[0078] Multiple joints J1 are formed in the overlapping region R1 between the anode lead 22b and the first to third anode leads 31A to 31C, connecting the first to third anode leads 31A to 31C to the metal portion of the anode foil 22. Two adjacent joints J1 are connected via the metal portion of the anode foil 22. In the portion of the overlapping region R1 other than the multiple joints J1, a dielectric layer is sandwiched between the first to third anode leads 31A to 31C and the metal portion of the anode foil 22.

[0079] Such multiple joints J1 can also be formed by irradiating the top wall portion 31a of the first anode lead 31A with a laser. During laser irradiation, in addition to forming a lattice structure similar to the first embodiment described above, molten metal material (the constituent material of the metal portions of the first to third anode leads 31A to 31C and each anode foil 22) melts into the side wall portion 31b of the first anode lead 31A, thus achieving integration. This enables a more robust joint structure.

[0080] It should be noted that in this embodiment, the first anode lead 31A has a sidewall portion 31b, but it is not limited thereto; the first anode lead 31A may also only have a portion equivalent to the top wall portion 31a. In this case, at the end of the overlapping region R1 ( Figure 4 During the process of forming multiple joints J1 by irradiating the left end of the middle with a laser, the constituent materials of the first to third anode leads 31A to 31C melt out and can form a structure equivalent to at least a part of the sidewall portion 31b.

[0081] Postscript

[0082] The following technology has been disclosed through the above description of the embodiments.

[0083] (Technology 1)

[0084] An electrolytic capacitor comprising stacked elements,

[0085] The above-mentioned stacked elements include:

[0086] At least one capacitor element having an anode foil and a cathode foil, the anode foil comprising a metal portion and a dielectric layer formed on the surface of the metal portion, the cathode foil being opposite the anode foil across a separator;

[0087] Anode lead, which is electrically connected to the aforementioned anode foil; and

[0088] The cathode lead is electrically connected to the aforementioned cathode foil.

[0089] The aforementioned anode foil has an anode body and an anode lead-out portion.

[0090] The cathode foil is opposite to the dielectric layer formed on the anode body.

[0091] A portion of the aforementioned anode lead overlaps with the aforementioned anode lead-out portion.

[0092] Multiple joints are formed in the overlapping area between the anode lead and the anode wire, and the multiple joints connect the anode wire to the metal portion of the anode foil.

[0093] Two adjacent joints of the aforementioned plurality of joints are connected via the aforementioned metal portion of the aforementioned anode foil.

[0094] In the portion of the overlapping region other than the plurality of joints, the dielectric layer is sandwiched between the anode lead and the metal portion of the anode foil.

[0095] (Technology 2)

[0096] According to the electrolytic capacitor described in Technique 1, in the aforementioned overlapping region, the ratio (T1 / T2) of the total thickness T1 of the anode foil and the anode lead of each of the plurality of joints relative to the total thickness T2 of the anode foil and the anode lead in the portion excluding the plurality of joints is 0.7 or more and 1.2 or less.

[0097] (Technology 3)

[0098] According to the electrolytic capacitor described in Artificial Intelligence 1 or 2, the metal portion of the anode foil has a core and a porous portion disposed on the outer side of the core.

[0099] The maximum width of each of the aforementioned joints is greater than the thickness of the core portion of the aforementioned metal portion of the aforementioned anode foil.

[0100] (Technology 4)

[0101] According to any one of the techniques 1 to 3, the shortest distance between two adjacent junctions is greater than 0 μm and less than 300 μm.

[0102] (Technology 5)

[0103] According to any one of the techniques 1 to 4, the electrolytic capacitor wherein the maximum width of each of the plurality of joints is 100 μm or less.

[0104] (Technology 6)

[0105] According to any one of the techniques 1 to 5, in the aforementioned overlapping region, there is no through hole extending along the thickness direction of the anode foil at the position in contact with the aforementioned plurality of joints.

[0106] (Technology 7)

[0107] According to any one of the techniques 1 to 6, in the electrolytic capacitor, the proportion of insulating material constituting the dielectric layer in the plurality of joints is 0% or more and 20% or less by volume.

[0108] (Technology 8)

[0109] According to any one of the claims 1 to 7, the electrolytic capacitor is composed of a plurality of capacitor elements stacked on top of each other and including adjacent first capacitor elements and second capacitor elements.

[0110] The anode lead of the anode foil of the first capacitor element and the anode lead of the anode foil of the second capacitor element are joined together at the plurality of joints.

[0111] In the vicinity of each of the aforementioned plurality of joints, the interval between the anode lead of the anode foil of the first capacitor element and the anode lead of the anode foil of the second capacitor element is 0% or more and 20% or less of the thickness of the anode foil.

[0112] (Technology 9)

[0113] A method for manufacturing an electrolytic capacitor, comprising:

[0114] The first step involves preparing an anode foil having a metal portion and a dielectric layer formed on the surface of the metal portion;

[0115] In the second step, a cathode foil is laminated over at least a portion of the dielectric layer with a diaphragm in between, thereby forming at least one capacitor element; and

[0116] In the third step, an anode lead is overlapped on the anode lead portion of the anode foil that is not opposite to the cathode foil, and the anode lead is irradiated with a laser to form a plurality of joints by joining the anode lead to the metal portion of the anode foil.

[0117] (Technology 10)

[0118] According to the manufacturing method of the electrolytic capacitor described in Technique 9, the portion of the anode foil that becomes the junction is not perforated before the second step described above.

[0119] (Technology 11)

[0120] According to the manufacturing method of the electrolytic capacitor described in Technique 9 or 10, in the third step described above, the anode lead is irradiated with the laser so that the dielectric layer is repelled in the junction and the anode lead is joined to the metal portion of the anode foil.

[0121] Industrial availability

[0122] This disclosure can be used for electrolytic capacitors and methods for manufacturing electrolytic capacitors.

[0123] Preferred embodiments of the present invention have been described, but such disclosure should not be interpreted as restrictive. Various modifications and alterations will be readily apparent to those skilled in the art upon reading the above disclosure. Therefore, the scope of the appended claims should be interpreted as including all modifications and alterations without departing from the true spirit and scope of the invention.

[0124] Explanation of reference numerals in the attached figures

[0125] 10: Electrolytic capacitors

[0126] 20: Stacked components

[0127] 21: Capacitor Components

[0128] 22: Anode foil

[0129] 22a: Anode body

[0130] 22b: Anode lead-out section

[0131] 22c: Core

[0132] 22d: Porous part

[0133] 23: Cathode foil

[0134] 23a: Cathode body

[0135] 23b: Cathode lead-out section

[0136] 24: Diaphragm

[0137] 31: Anode lead

[0138] 31A: First anode lead

[0139] 31a: Top wall portion

[0140] 31b: Side wall portion

[0141] 31B: Second anode lead

[0142] 31C: Third anode lead

[0143] 32: Cathode lead

[0144] 40: Shell

[0145] D: Shortest distance between joints

[0146] J1: Joint (Anode side)

[0147] J2: Joint (cathode side)

[0148] R1: Overlapping region (anode side)

[0149] R2: Overlapping region (cathode side)

[0150] T: Core thickness

[0151] T1: Total thickness (joint)

[0152] T2: Total thickness (excluding joints)

[0153] W: Maximum width of the joint

Claims

1. An electrolytic capacitor comprising stacked elements, The stacked element includes: At least one capacitor element having an anode foil and a cathode foil, the anode foil comprising a metal portion and a dielectric layer formed on the surface of the metal portion, the cathode foil being opposite the anode foil across a separator; Anode lead, which is electrically connected to the anode foil; and The cathode lead is electrically connected to the cathode foil. The anode foil has an anode body and an anode lead-out portion. The cathode foil is opposite to the dielectric layer formed on the anode body. A portion of the anode lead overlaps with the anode lead-out portion. Multiple joints are formed in the overlapping area between the anode lead and the anode wire, the multiple joints joining the anode wire to the metal portion of the anode foil. Two adjacent joints of the plurality of joints are connected via the metal portion of the anode foil. In the portion of the overlapping region other than the plurality of joints, the dielectric layer is sandwiched between the anode lead and the metal portion of the anode foil.

2. The electrolytic capacitor according to claim 1, wherein, In the overlapping region, the ratio of the total thickness T1 of the anode foil and the anode lead of each of the plurality of joints to the total thickness T2 of the anode foil and the anode lead in the portion excluding the plurality of joints, i.e., T1 / T2, is 0.7 or more and 1.2 or less.

3. The electrolytic capacitor according to claim 1 or 2, wherein, The metal portion of the anode foil has a core and a porous portion disposed on the outer side of the core. The maximum width of each of the plurality of joints is greater than the thickness of the core portion of the metal portion of the anode foil.

4. The electrolytic capacitor according to claim 1 or 2, wherein, The shortest distance between two adjacent joints is greater than 0 μm and less than 300 μm.

5. The electrolytic capacitor according to claim 1 or 2, wherein, The maximum width of each of the plurality of joints is less than 100 μm.

6. The electrolytic capacitor according to claim 1 or 2, wherein, In the overlapping region, there are no through holes extending along the thickness direction of the anode foil at the locations that contact the plurality of joints.

7. The electrolytic capacitor according to claim 1 or 2, wherein, The proportion of insulating material constituting the dielectric layer in the plurality of joints is more than 0% by volume and less than 20% by volume.

8. The electrolytic capacitor according to claim 1 or 2, wherein, The at least one capacitor element is composed of a plurality of capacitor elements stacked on top of each other and including adjacent first capacitor elements and second capacitor elements. The anode lead of the anode foil of the first capacitor element and the anode lead of the anode foil of the second capacitor element are joined together at the plurality of joints. In the vicinity of each of the plurality of joints, the interval between the anode lead of the anode foil of the first capacitor element and the anode lead of the anode foil of the second capacitor element is more than 0% and less than 20% of the thickness of the anode foil.

9. A method for manufacturing an electrolytic capacitor, comprising: The first step involves preparing an anode foil having a metal portion and a dielectric layer formed on the surface of the metal portion; In the second step, cathode foils are stacked across at least a portion of the dielectric layer via a diaphragm, thereby forming at least one capacitor element; as well as In the third step, an anode lead is overlapped on the anode lead portion of the anode foil that is not opposite to the cathode foil, and the anode lead is irradiated with a laser to form a plurality of joints by joining the anode lead to the metal portion of the anode foil.

10. The method for manufacturing an electrolytic capacitor according to claim 9, wherein, Before the second process, the portion of the anode foil that forms the junction is not perforated.

11. The method for manufacturing an electrolytic capacitor according to claim 9 or 10, wherein, In the third step, the anode lead is irradiated with the laser so that the dielectric layer is repelled in the junction and the anode lead is bonded to the metal portion of the anode foil.

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