Method for manufacturing electrolytic capacitor

Abstract

To provide a manufacturing method suitable for a hybrid electrolytic capacitor SOLUTION: The disclosed manufacturing method includes (i) preparing an anode base material in which a metal foil is exposed at an end surface, (ii) connecting a plurality of anode lead members to the anode base material and forming a second dielectric layer on the end surface, (iii) forming a plurality of anode bodies to which the anode lead members are connected by cutting the anode base material into a predetermined length, (iv) forming a stacked body by stacking the anode bodies, a cathode body, and a separator, and (v) impregnating the stacked body with a conductive polymer and an electrolyte solution. The step (ii) includes a step (ii-a) of connecting the plurality of anode lead members to the anode base material, and a step (ii-b) of forming the second dielectric layer on the end surface by immersing the anode base material in an anodizing solution to perform anodizing treatment.SELECTED DRAWING: Figure 1C

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrolytic capacitor. [Background technology]

[0002] An electrolytic capacitor includes an anode body and a dielectric layer formed on the surface of the anode body. In general, the dielectric layer is formed by anodizing the surface of the anode body (chemical conversion treatment).

[0003] Various anodizing methods have been proposed in the past. Patent Document 1 (JP 2017-168740 A) discloses a method for manufacturing an electrolytic capacitor, including: a first step of winding up an anode foil having a first dielectric film formed thereon and a cathode foil facing the anode foil to form a wound element; and a second step of applying a voltage from a DC power source between the anode foil and the liquid storage tank while immersing the wound element in a chemical solution stored in a conductive liquid storage tank, thereby forming a second dielectric film on the anode foil, wherein in the second step, the cathode foil is discharged to lower the potential of the cathode foil.

[0004] Furthermore, Patent Document 2 (JP 04-312912 A) and Patent Document 3 (JP 04-312913 A) disclose methods for manufacturing electrode terminals for electrolytic capacitors. For example, Patent Document 2 discloses "a method for manufacturing an electrode terminal for an electrolytic capacitor, which comprises forming an aluminum tab consisting of a chemically converted flat portion and round bar portions on both sides of the flat portion, joining lead wires to the round bar portions, crimping the flat portions to tape-shaped aluminum foil at predetermined intervals, winding each aluminum tab around the aluminum foil, and then winding the aluminum tabs around a take-up reel, followed by re-chemical conversion treatment." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-168740 [Patent Document 2] Japanese Patent Application Publication No. 04-312912 [Patent Document 3] Japanese Patent Application Publication No. 04-312913 Summary of the Invention [Problem to be solved by the invention]

[0006] Electrolytic capacitors (hybrid electrolytic capacitors) that use conductive polymers and electrolytic solutions as electrolytes are used in a variety of fields due to their excellent performance. Hybrid electrolytic capacitors are sometimes used in applications requiring high rated voltages. For this reason, it may not be desirable to directly use the dielectric layer formation method used in general aluminum electrolytic capacitors or solid electrolyte capacitors as the method for forming the dielectric layer of a hybrid electrolytic capacitor. In this situation, one of the objectives of the present disclosure is to provide a manufacturing method suitable for hybrid electrolytic capacitors. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to a method for manufacturing an electrolytic capacitor, which includes a laminate of an anode body having a predetermined length and a predetermined width and a dielectric layer formed on a surface thereof, a separator, and a cathode body, and the method includes the steps of: (i) preparing an anode base including a strip-shaped metal foil having a length at least twice the predetermined length and the predetermined width and a first dielectric layer formed on each of the two main surfaces of the metal foil, the metal foil being exposed at an end surface; (ii) connecting a plurality of anode lead members to the anode base and forming a second dielectric layer on the end surface; and (iii) cutting the anode base after step (ii) to the predetermined length, thereby obtaining an electrolytic capacitor. The method includes a step (iii) of forming a plurality of the anode bodies each having the anode lead member connected thereto; a step (iv) of forming the laminate by stacking the anode body, the cathode body, and the separator such that the separator is disposed between the anode body and the cathode body formed in the step (iii); and a step (v) of impregnating the laminate with a conductive polymer and an electrolyte solution, wherein the step (ii) includes a step (ii-a) of connecting the plurality of anode lead members to the anode base material, and a step (ii-b) of forming the second dielectric layer on the end surface by immersing the anode base material in a chemical conversion solution to perform chemical conversion treatment. [Effects of the Invention]

[0008] According to the present disclosure, a hybrid electrolytic capacitor can be manufactured using a manufacturing method suitable for a hybrid electrolytic capacitor. The novel features of the present invention are set forth in the appended claims, but the present invention, both in terms of structure and content, together with other objects and features of the present invention, will be better understood from the following detailed description taken in conjunction with the drawings. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1 is a schematic diagram illustrating one step of an example of a manufacturing method according to the present disclosure. [Figure 1B] FIG. 1B is a diagram schematically illustrating an example of a step subsequent to the step in FIG. 1A. [Figure 1C]FIG. 1C is a diagram schematically illustrating an example of a step subsequent to the step in FIG. 1B. [Figure 1D] FIG. 1D is a diagram schematically illustrating an example of a step subsequent to the step in FIG. 1C. [Figure 1E] FIG. 1B is a diagram schematically illustrating an example of a step subsequent to the step in FIG. 1D. [Figure 2] 1 is a cross-sectional view schematically illustrating an example of an electrolytic capacitor manufactured by a manufacturing method according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Below, embodiments of the manufacturing method according to the present disclosure will be described using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure are obtained. In this specification, the expression "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "numerical value A or more and numerical value B or less." In the following description, when lower and upper limits are exemplified for numerical values ​​of specific physical properties or conditions, any of the exemplified lower limits can be arbitrarily combined with any of the exemplified upper limits, as long as the lower limit is not equal to or greater than the upper limit.

[0011] (Method of manufacturing electrolytic capacitors) The manufacturing method of this embodiment is a method for manufacturing an electrolytic capacitor including a laminate of an anode body having a predetermined length L2 and a predetermined width W2 and a dielectric layer formed on the surface thereof, a separator, and a cathode body. The separator is disposed between the anode body and the cathode body. The laminate may be composed of a plurality of sheet-shaped anode bodies and a plurality of sheet-shaped cathode bodies alternately arranged, and a separator disposed between the anode body and the cathode body. Alternatively, the laminate may be a wound body formed by winding a strip-shaped anode body, a strip-shaped cathode body, and a strip-shaped separator such that the separator is disposed between the anode body and the cathode body. In the wound body, the anode body, the cathode body, and the separator are stacked in the radial direction of the wound body.

[0012] The predetermined width W2 may be 10 mm or more, 15 mm or more, or 20 mm or more. The width W2 may be 50 mm or less, or 40 mm or less. For example, the width W2 may be in the range of 10 mm to 50 mm, the range of 15 mm to 50 mm, or the range of 20 mm to 50 mm. In any of these ranges, the upper limit may be 40 mm.

[0013] The predetermined length L2 is longer than the width W2. The length L2 may be 100 mm or more, 200 mm or more, or 300 mm or more. The length L2 may be 1000 mm or less, or 800 mm or less. For example, the length L2 may be in the range of 100 to 1000 mm, 200 to 1000 mm, or 300 to 1000 mm. In any of these ranges, the upper limit may be 800 mm. The length L2 may be two times or more, or 100 times or less, the width W2.

[0014] There are no particular limitations on the thickness of the anode body, and it may be in the range of 80 μm to 200 μm (for example, in the range of 100 μm to 130 μm).

[0015] The manufacturing method of this embodiment includes the following steps (i) to (v) in this order. (Step (i)) Step (i) is a step of preparing an anode substrate including a strip-shaped metal foil having a length L1 at least twice the predetermined length L2 (the length of the anode body of the electrolytic capacitor) and a predetermined width W2 (the width of the anode body of the electrolytic capacitor), and a first dielectric layer formed on both main surfaces of the metal foil, where the metal foil is exposed at the edge surfaces (or cut surfaces). The metal foil is a metal foil (e.g., aluminum foil) that can be used as an anode body of an electrolytic capacitor. Typically, the two main surfaces of the anode body (metal foil) are roughened (or porous). The length L1 may be 2 times or more, 10 times or more, or 100 times or more, or 10,000 times or less, 5,000 times or less, or 1,000 times or less, of the length L2. The length L1 may be in the range of 2 to 10,000 times (e.g., 100 to 5,000 times) the length L2. By increasing the value of L1 / L2, it is possible to produce a large number of anode bodies at once, while by keeping the value of L1 / L2 at a moderate value or less, the anode substrate becomes easier to handle.

[0016] A commercially available anode substrate may be used as the anode substrate. Alternatively, the anode substrate may be formed by the following method. First, the surface of the sheet-shaped metal foil is roughened, and then a first dielectric layer is formed on the roughened surface (step (ia)). The length L0 of the sheet-shaped metal foil is at least 1 time (e.g., in the range of 1 to 10 times) the length L1, and the width W0 of the sheet-shaped metal foil is at least 2 times (e.g., in the range of 5 to 500 times) the width W2. The roughening may be performed by a known method (e.g., etching). In step (ia), first dielectric layers are formed on the two main surfaces of the sheet-shaped metal foil (more specifically, on the roughened main surfaces). The first dielectric layer may be formed by chemical conversion treatment. The first dielectric layer formed by chemical conversion treatment is an oxide of the metal constituting the metal foil (the same applies to the chemical conversion treatment described below). For example, when the sheet-shaped metal foil is an aluminum foil, an aluminum oxide layer is formed by chemical conversion treatment. The method and conditions for roughening and chemical conversion treatment in step (i) are not particularly limited, and known methods and conditions may be used.

[0017] The chemical conversion treatment method in step (ia) is not limited, and any known chemical conversion treatment method used to form a dielectric layer on the surface of an anode body of an electrolytic capacitor may be used. The thickness of the first dielectric layer is determined depending on the performance required of the electrolytic capacitor. When manufacturing an electrolytic capacitor with a high rated voltage, the thickness of the first dielectric layer is increased. For example, when manufacturing an electrolytic capacitor with a rated voltage of 100 V, the thickness of the first dielectric layer may be 200 nm or more.

[0018] Next, the sheet metal foil that has been subjected to step (ia) is cut to the size of the anode substrate (step (ib)). For example, the sheet metal foil wound in a roll may be cut into multiple rolls so that each roll has a width of W2. At this time, no dielectric layer is formed on the cut surfaces (edge ​​surfaces), and the metal foil is exposed at the cut surfaces (edge ​​surfaces).

[0019] (Step (ii)) Step (ii) is a step of connecting a plurality of anode lead members to the anode substrate and forming a second dielectric layer on the end surface. Step (ii) includes step (ii-a) of connecting a plurality of anode lead members to the anode substrate and step (ii-b) of forming a second dielectric layer on the end surface by immersing the anode substrate in a chemical conversion solution. Note that the second dielectric layer is formed by chemical conversion treatment (anodic oxidation) of the anode substrate, and is therefore typically made of the same material as the first dielectric layer. For example, if the anode substrate is made of aluminum, the second dielectric layer is an aluminum oxide layer.

[0020] In step (ii), step (ii-b) is usually carried out after step (ii-a), although step (ii-a) may also be carried out after step (ii-b).

[0021] The anode lead member is not particularly limited, and a known anode lead member may be used. For example, an anode lead member may be used that includes a plate-shaped portion fixed and connected to the anode substrate, a rod-shaped portion connected to the plate-shaped portion, and a lead portion connected to the rod-shaped portion. The anode lead member may be formed of a metal. The rod-shaped portion corresponds to the protrusion described below. The plate-shaped portion is made of a metal such as aluminum. The rod-shaped portion may be a rod-shaped iron whose surface is coated with a metal other than iron (e.g., copper and / or tin). The metal coating the surface may be formed by plating or by other methods. A linear metal may be used for the lead portion. The end of the anode lead member (e.g., the plate-shaped portion) is fixed to the anode substrate by welding, crimping, or the like, and is electrically connected to the anode substrate.

[0022] The multiple anode lead members are arranged at a predetermined interval. Typically, the interval is the same as the length L2 (the length of the anode body of the electrolytic capacitor). This ensures that one anode lead member is arranged for one anode body when the anode substrate is cut in step (iii).

[0023] In step (ii-b), the chemical conversion treatment is performed while at least the anode substrate is immersed in a chemical conversion solution, which may be an aqueous solution of an acid salt such as a phosphate, a borate, or an adipate, or another aqueous solution such as an aqueous solution of phosphoric acid.

[0024] In a typical wound-type electrolytic capacitor, a wound body is fabricated, which includes an anode foil, a cathode foil, and a separator, each having a dielectric layer formed on its surface. Then, a chemical conversion treatment is performed to form a dielectric layer on the end surface of the anode foil (the portion without the dielectric layer). In this case, the chemical conversion solution tends to remain inside the wound body, including the separator, and the components of the chemical conversion solution may have adverse effects. In particular, when the width W2 is large, the chemical conversion solution tends to remain inside the wound body. Therefore, in conventional methods, it is difficult to use a chemical conversion solution with a high concentration. However, in the method disclosed herein, the end surface of the anode body is subjected to the chemical conversion treatment before the wound body is formed. Therefore, the chemical conversion solution adhering to the surface of the anode body during the chemical conversion treatment can be easily removed by cleaning or the like after the chemical conversion treatment. Therefore, the method disclosed herein allows the use of a chemical conversion solution with a high concentration (in other words, a chemical conversion solution with high electrical conductivity).

[0025] The electrical conductivity of the chemical conversion solution may be 1 mS / cm or more, or may be 0.1 mS / cm or more. By making the electrical conductivity of the chemical conversion solution 0.1 mS / cm or more, the formation rate of the second dielectric layer can be increased. When manufacturing an electrolytic capacitor with a high rated voltage, the second dielectric layer needs to be thick, just like the first dielectric layer. Therefore, it is particularly important to increase the formation rate of the second dielectric layer by using a chemical conversion solution with a high concentration (a chemical conversion solution with high electrical conductivity). There is no particular upper limit for the electrical conductivity of the chemical conversion solution, but it may be 100 mS / cm or less.

[0026] The thickness of the second dielectric layer formed by the chemical conversion treatment in step (ii-b) may be 200 nm or more, or may be 150 nm or more. By forming a second dielectric layer with a thickness of 150 nm or more in step (ii-b), an electrolytic capacitor with a high rated voltage can be manufactured. There is no particular upper limit to the thickness of the second dielectric layer, but it may be, for example, 800 nm or less (the same applies to the first dielectric layer).

[0027] The voltage applied during the chemical conversion treatment may be 300 V or more, or may be 200 V or more. In step (ii-b), the formation rate of the second dielectric layer can be increased by chemically treating the anode substrate at a chemical conversion voltage of 200 V or more. There is no particular upper limit to the applied voltage, but it may be 600 V or less.

[0028] In a typical conventional manufacturing method, the end surface of an anode body is subjected to a chemical conversion treatment while the anode body, cathode body, and separator are in a wound state. In this case, if a high applied voltage (e.g., 200 V or more) is applied to the chemical conversion treatment, there is a problem that discharge occurs between the anode lead to which the high voltage is applied and the cathode lead member located nearby. However, the method disclosed herein can avoid such a problem.

[0029] In step (ii-b), it is preferable to perform the chemical conversion treatment while the part of the anode lead member protruding from the anode substrate is also immersed in the chemical conversion solution, so that a chemical conversion coating (dielectric layer) can be formed on the surface of that part as well.

[0030] The anode lead member may include a metal connection portion connected to the anode substrate and a lead portion connected to the connection portion. The connection portion may include a plate-shaped portion in contact with the anode substrate and a protruding portion protruding from the anode substrate without contacting the anode substrate. In a preferred example, the length of the protruding portion is 2 mm or more, and in step (ii-b), the length of the portion of the protruding portion immersed in the chemical conversion solution is 1 mm or less. This prevents the chemical conversion solution from reaching the joint between the protruding portion and the lead portion, resulting in corrosion breakage of the lead member and insufficient formation of the chemical conversion coating (dielectric layer). There is no particular upper limit to the length of the protruding portion, but it may be, for example, 5 mm or less. The length of the portion of the protruding portion immersed in the chemical conversion solution is, for example, 0 mm or more, and the protruding portion may not be immersed in the chemical conversion solution. The protruding portion may be, for example, the rod-shaped portion described above.

[0031] In step (ii-b), the chemical conversion treatment may be performed on the anode substrate in a flat state or in a rolled state. For example, the chemical conversion treatment may be performed on the anode substrate in a rolled state. In this case, providing a certain amount of gap between overlapping anode substrates in the radial direction of the roll allows the chemical conversion solution to be sufficiently distributed throughout the roll. Therefore, unlike when the chemical conversion treatment is performed on a wound capacitor element, a dielectric layer with less variation from location to location can be formed. By performing the chemical conversion treatment on the wound anode substrate in step (ii-b), the chemical conversion treatment can be performed efficiently. Note that when the width W2 is large, performing the chemical conversion treatment on a wound capacitor element tends to result in insufficient distribution of the chemical conversion solution throughout the wound capacitor element, resulting in large variations in the thickness of the dielectric layer. Therefore, the method according to the present disclosure is particularly effective when the width W2 is large (e.g., when W2 is 10 mm or greater).

[0032] (Step (iii)) Step (iii) is a step of cutting the anode substrate that has been subjected to step (ii) to a predetermined length L2 to form a plurality of anode bodies each connected to an anode lead member. There is no limitation on the method for cutting the anode substrate, and any known method may be used. At least one (usually one) anode lead member is connected to each formed anode body.

[0033] The metal foil is exposed at the cut surface formed by step (iii). However, since the width direction W2 is shorter than the length L2, the impact of the metal foil exposed in step (iii) is small. After forming the laminate in step (iv), a supplementary chemical conversion treatment may be performed. In this case, the chemical conversion treatment may be performed under milder conditions than those in step (ii-b) (e.g., a low applied voltage or a chemical conversion solution with low electrical conductivity).

[0034] (Step (iv)) Step (iv) is a step of forming a laminate by stacking anode bodies, cathode bodies, and separators such that the separator is disposed between the anode body formed in step (iii) and the cathode body. For example, a strip-shaped anode body, a strip-shaped cathode body, and a strip-shaped separator may be wound such that the separator is disposed between the anode body and the cathode body. This forms a wound body (laminate). Alternatively, a plurality of anode bodies, a plurality of cathode bodies, and a plurality of separators may be stacked such that the separator is disposed between the anode body and the cathode body. The plurality of anode bodies and the plurality of cathode bodies are arranged alternately. Step (iv) can be performed by a known method.

[0035] The separator may be a sheet-like material that can be impregnated with an electrolyte, such as an insulating sheet-like material that can be impregnated with an electrolyte. The separator may be a woven fabric, a nonwoven fabric, or a porous membrane. Examples of separator materials include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamide, polyimide, polyamideimide, polyetherimide, rayon, and glass.

[0036] When manufacturing electrolytic capacitors with high rated voltages, the separator surface density is 20 g / m 2 It is preferable that this is equal to or greater than this.

[0037] (cathode body) The cathode body can be made of a metal foil (such as aluminum foil) that can be used as a cathode for an electrolytic capacitor. The surface of the metal foil may be coated with a layer made of carbon, nickel, titanium, or the like.

[0038] There are no particular limitations on the thickness of the cathode body, and it may be in the range of 20 μm to 100 μm (for example, in the range of 30 μm to 60 μm). The size and shape of the cathode body are approximately the same as those of the anode body.

[0039] (Process (v)) Step (v) is a step of impregnating the laminate with a conductive polymer and an electrolyte solution. The method for performing step (v) is not particularly limited, and can be performed by a known method. In a preferred example, the laminate is first impregnated with the conductive polymer, and then the laminate is impregnated with the electrolyte solution.

[0040] The conductive polymer may be impregnated into the laminate by immersing the laminate in a dispersion containing the conductive polymer. Alternatively, the conductive polymer may be disposed on the dielectric layer by polymerizing raw material monomers on the dielectric layer of the anode body. These processes may be performed by known methods. The electrolyte solution can be impregnated into the laminate by immersing the laminate in the electrolyte solution. In this way, a laminate (capacitor element) is obtained in which a separator and an electrolyte are disposed between the dielectric layer of the anode body and the cathode body.

[0041] Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and derivatives thereof. These conductive polymers may be used alone or in combination. The conductive polymer may also be a copolymer of two or more monomers. A preferred example of the conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0042] A dopant may be added to the conductive polymer. From the viewpoint of suppressing dedoping from the conductive polymer, it is preferable to use a polymer dopant. Examples of polymer dopants include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, etc. These may be used alone or in combination of two or more. A preferred example of the dopant is polystyrene sulfonic acid (PSS).

[0043] The electrolyte may be a known electrolyte used in electrolytic capacitors. The electrolyte may contain a non-aqueous solvent and a base component and / or an acid component dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include polyhydric alcohols such as ethylene glycol and propylene glycol, cyclic sulfones such as sulfolane (SL), lactones such as γ-butyrolactone (γBL), amides such as N-methylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone, esters such as methyl acetate, carbonate compounds such as propylene carbonate, ethers such as 1,4-dioxane, ketones such as methyl ethyl ketone, and formaldehyde. Alternatively, the non-aqueous solvent may be a polyalkylene glycol or a derivative of a polyalkylene glycol. The non-aqueous solvent of the electrolyte may be composed of one or more non-aqueous solvents.

[0044] Examples of the acid component include acids such as maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcylic acid. Inorganic acids such as phosphoric acid, phosphorous acid, hypophosphorous acid, boric acid, fluoroboric acid, tetrafluoroboric acid, and hexafluorophosphoric acid may also be used as the acid component. Alternatively, organic acids such as alkanesulfonic acids, such as methanesulfonic acid, may also be used as the acid component. Alternatively, a composite compound of an organic acid and an inorganic acid may also be used as the acid component.

[0045] The base component may be a compound having an alkyl-substituted amidine group, such as an imidazole compound, a benzimidazole compound, or an alicyclic amidine compound (a pyrimidine compound, an imidazoline compound). Alternatively, a quaternary salt of a compound having an alkyl-substituted amidine group may be used as the base component. Alternatively, a tertiary amine may be used as the base component. The solute dissolved in the nonaqueous solvent may be one type or multiple types.

[0046] After step (v), an electrolytic capacitor is manufactured using the laminate (capacitor element) that has undergone step (v). For example, the capacitor element may be housed in a case and the case may be sealed. There are no limitations to these methods, and known materials and known methods may be used. In this way, a hybrid electrolytic capacitor can be manufactured. Note that at least a portion of the electrolytic solution may be poured into the case after the laminate is housed in the case.

[0047] When only an electrolytic solution is used as the electrolyte, even if the exposed portions of the metal foil (e.g., end faces) are not subjected to chemical conversion treatment, the action of the electrolytic solution will form a certain amount of dielectric layer on the exposed portions. Therefore, in such cases, chemical conversion treatment of the end faces is not particularly important. On the other hand, in hybrid electrolytic capacitors, the amount of electrolytic solution is small, so the effect of the electrolytic solution in forming the dielectric layer may be insufficient. Therefore, in hybrid electrolytic capacitors, it is important to chemically treat the metal foil exposed at the end faces to form a dielectric layer. Furthermore, hybrid electrolytic capacitors may require a high rated voltage due to their characteristics. To achieve a high rated voltage, the dielectric layer on the end faces must be thick. For these reasons, the manufacturing method disclosed herein is particularly effective when manufacturing hybrid electrolytic capacitors.

[0048] An example of a manufacturing method according to the present disclosure will be specifically described below with reference to the drawings. However, the present disclosure is not limited to the following embodiments. The example manufacturing method described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiments. Note that the following drawings are schematic diagrams, and the scales (e.g., aspect ratios) of the illustrated components differ from the scales of the actual components.

[0049] (Embodiment 1) In embodiment 1, an example of a manufacturing method according to the present disclosure will be described. First, as shown in FIG. 1A, the above-described anode substrate 200 is prepared (step (i)). The anode substrate 200 has the width W2 and the length L1 described above. The two main surfaces 200a of the anode substrate 200 are roughened, and a first dielectric layer (not shown) is formed on the surfaces. The metal foil constituting the anode substrate 200 is exposed at the end surface (cut surface) 200s of the anode substrate 200.

[0050] Next, as shown in FIG. 1B , a plurality of anode lead members 210 are connected to the anode substrate 200 (step (ii-a)). The anode lead member 210 includes a plate-shaped portion 211, a rod-shaped portion (protruding portion) 212 connected to the plate-shaped portion 211, and a lead portion 213 connected to the rod-shaped portion 212. The plate-shaped portion 211 is fixed to the anode substrate 200, thereby electrically connecting the anode lead member 210 to the metal foil that constitutes the anode substrate 200. The rod-shaped portion 212 protrudes from the anode substrate 200. The plurality of anode lead members 210 are fixed to the anode substrate 200 at intervals of length L2. Note that although two anode lead members 210 are shown in FIG. 2 , more anode lead members 210 are connected to the anode substrate 200.

[0051] Next, as shown in FIG. 1C, the anode substrate 200 is immersed in a chemical conversion solution 301 for chemical conversion treatment. Specifically, a DC voltage is applied between the anode substrate 200 and a counter electrode. FIG. 1C shows an example in which a container 302 containing the chemical conversion solution 301 is used as a conductive container and as a counter electrode. Of course, a counter electrode separate from the container 302 may also be placed in the chemical conversion solution 301 for chemical conversion treatment. This chemical conversion treatment forms a second dielectric layer (not shown) on the end surface 200s of the anode substrate 200 (step (ii-b)). As shown in FIG. 1C, the chemical conversion treatment is preferably performed while a portion of the rod-shaped portion 212 is immersed in the chemical conversion solution 301.

[0052] 1C shows an example in which the chemical conversion treatment is performed on the anode substrate 200 in an unwound state. However, as described above, the chemical conversion treatment may also be performed on the anode substrate 200 in a rolled state. Because the anode substrate 200 has multiple plate-shaped portions 211 fixed thereto, even when the anode substrate 200 is rolled, gaps are formed between the anode substrates 200 stacked in the radial direction of the roll. Therefore, even when the anode substrate 200 is rolled, the chemical conversion solution can sufficiently penetrate into the roll.

[0053] Next, as shown in FIG. 1D, the anode substrate 200 on which the second dielectric layer (not shown) is formed is cut at predetermined lengths L2 to form a plurality of anode bodies 21 connected to the anode lead members 210 (step (iii)).

[0054] Next, as shown in FIG. 1E , anode body 21, cathode body 22, and separator 23 are stacked (wound) together so that separator 23 is disposed between formed anode body 21 and cathode body 22, thereby forming laminate (wound body) 20 (step (iv)). The outermost periphery of the wound body is fixed with a winding stop tape 24. FIG. 1E shows a partially unfolded state of the wound body before the outermost periphery is fixed. A cathode lead member 220 is connected to cathode body 22. Like anode lead member 210, cathode lead member 220 includes a plate-shaped portion (not shown), a rod-shaped portion (protruding portion) 222, and a lead portion 223.

[0055] Next, laminate 20 is impregnated with a conductive polymer and an electrolyte solution by the method described above (step (v)). In this manner, capacitor element 10 is formed. By housing formed capacitor element 10 in case 11, electrolytic capacitor 100 shown in FIG. 2 is obtained.

[0056] 2 includes a capacitor element 10, a cylindrical case 11 with a bottom that houses the capacitor element 10, a sealing member 12 that closes the opening of the case 11, and a seat plate 13 that covers the sealing member 12. The capacitor element 10 is housed in the case 11. The vicinity of the open end of the case 11 is drawn inward, and the open end of the case 11 is curled so as to crimp the sealing member 12. [Industrial Applicability]

[0057] The present disclosure can be used in a method for manufacturing an electrolytic capacitor. While the present invention has been described in terms of presently preferred embodiments, such disclosure is not to be interpreted as limiting. Various changes and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. It is therefore intended that the appended claims be interpreted to cover all changes and modifications that do not depart from the true spirit and scope of the invention. [Explanation of symbols]

[0058] 10: Capacitor element 11: Case 12: Sealing member 20: Laminate 21: Anode body 22: Cathode body 23: Separator 100: Electrolytic capacitor 200: Anode base material 200a: Main surface 200s: End face 210: Anode lead member 211: Plate-shaped part 212: Rod-shaped part 213: Lead section 220: Cathode lead member 223: Lead section 301:Chemical liquid

Claims

1. A method for manufacturing an electrolytic capacitor including a laminate of an anode body having a predetermined length and a predetermined width and a dielectric layer formed on a surface thereof, a separator, and a cathode body, the method comprising: a step (i) of preparing an anode base material including a strip-shaped metal foil having a length at least twice the predetermined length and the predetermined width, and a first dielectric layer formed on two main surfaces of the metal foil, the metal foil being exposed at end surfaces; (ii) connecting a plurality of anode lead members to the anode substrate and forming a second dielectric layer on the end surface; a step (iii) of cutting the anode base material that has been subjected to the step (ii) to the predetermined length to form a plurality of the anode bodies to which the anode lead member is connected; step (iv) of stacking the anode body, the cathode body, and the separator so that the separator is disposed between the anode body and the cathode body formed in step (iii) to form the laminate; and (v) a step of impregnating the laminate with a conductive polymer and an electrolyte solution, The step (ii) a step (ii-a) of connecting the plurality of anode lead members to the anode substrate; and (ii-b) forming the second dielectric layer on the end surface by immersing the anode base material in a chemical conversion solution to perform chemical conversion treatment.

2. The manufacturing method according to claim 1, wherein in the step (ii-b), the second dielectric layer is formed to a thickness of 150 nm or more.

3. 3. The manufacturing method according to claim 1, wherein in the step (ii-b), the anode substrate is subjected to chemical conversion treatment at a chemical conversion voltage of 200 V or more.

4. The method according to any one of claims 1 to 3, wherein in the step (ii), the step (ii-b) is carried out after the step (ii-a).

5. The manufacturing method according to any one of claims 1 to 4, wherein in the step (ii-b), the chemical conversion treatment is performed in a rolled state of the anode substrate.

6. The areal density of the separator is 20 g / m ２ The manufacturing method according to any one of claims 1 to 5, wherein

7. The manufacturing method according to any one of claims 1 to 6, wherein the predetermined width is 10 mm or more.

8. the anode lead member includes a connection portion made of metal and connected to the anode base material, and a lead portion connected to the connection portion; the connection portion includes a plate-shaped portion in contact with the anode base material and a protruding portion protruding from the anode base material without contacting the anode base material, The length of the protrusion is 2 mm or more, The manufacturing method according to any one of claims 1 to 7, wherein in the step (ii-b), a length of a portion of the protrusion immersed in the chemical conversion solution is set to 1 mm or less.

9. The method according to any one of claims 1 to 8, wherein the chemical conversion solution has an electrical conductivity of 0.1 mS / cm or more.

10. The method according to any one of claims 1 to 9, wherein the rated voltage of the electrolytic capacitor is 100 V or more.

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