Electrolytic capacitor and method for manufacturing electrolytic capacitor

Abstract

The disclosed manufacturing method is for an electrolytic capacitor that includes a capacitor element. The manufacturing method includes, in this order: a step (i) for electrically connecting a positive-electrode lead terminal to a positive-electrode part, and electrically connecting a negative-electrode lead terminal to a negative-electrode part; and, a step (ii) for covering a portion of the positive-electrode lead terminal, a portion of the negative-electrode lead terminal, and the capacitor element with an exterior body containing a resin. The manufacturing method further includes, prior to step (ii), a plasma process step in which at least a portion of a metal surface of at least one lead terminal selected from the group consisting of the positive-electrode lead terminal and the negative-electrode lead terminal is subjected to a plasma process, thereby making the at least a portion a plasma process surface, whereby a method for manufacturing an electrolytic capacitor having high reliability is provided.

Description

Electrolytic capacitor and method for manufacturing the same

[0001] The present disclosure relates to electrolytic capacitors and methods for manufacturing the same.

[0002] An electrolytic capacitor includes a capacitor element, lead terminals (anode lead terminal and cathode lead terminal) connected to the capacitor element, and an exterior housing. The exterior housing contains a resin and covers part of the lead terminals and the capacitor element. A problem with electrolytic capacitors is that moisture and oxygen can enter from the outside, degrading the performance of the capacitor element.

[0003] A problem with electrolytic capacitors is that moisture and oxygen can penetrate from the outside, degrading the performance of the capacitor element. In particular, moisture and oxygen can easily reach the capacitor element through the surface of the lead terminals. Therefore, it is important to improve the adhesion between the outer casing and the lead terminals. Several technologies have been proposed to improve the adhesion between the outer casing and the lead terminals.

[0004] Patent Document 1 (JP 5-021290 A) discloses a solid electrolytic capacitor in which "an anodized film formed on a plate or foil made of valve metal is used as a dielectric, a dielectric polymer layer and a dielectric layer are sequentially formed on predetermined portions of this dielectric to form a capacitor element, a lead frame serving as a lead-out terminal is connected to the valve metal portion and the conductor layer portion of this capacitor element, and the capacitor element and a portion of the lead frame are further sheathed with a molding resin, wherein a solder alloy layer or a tin metal layer having a copper metal layer as an underlayer is formed on the surface of the lead frame other than the portion that comes into contact with the molding resin, and only a copper metal layer is formed on the portion of the lead frame that comes into contact with the molding resin, and the surface of the copper metal layer is roughened."

[0005] Japanese Patent Application Publication No. 5-021290

[0006] One aspect of the present disclosure relates to a method for manufacturing an electrolytic capacitor including a capacitor element having an anode portion and a cathode portion, the method comprising: (i) electrically connecting an anode lead terminal to the anode portion and electrically connecting a cathode lead terminal to the cathode portion; and (ii) covering a portion of the anode lead terminal, a portion of the cathode lead terminal, and the capacitor element with an exterior body containing a resin, in this order; and, prior to the step (ii), further comprising a plasma treatment step of subjecting at least a portion of a metal surface of at least one lead terminal selected from the group consisting of the anode lead terminal and the cathode lead terminal to plasma treatment to convert the at least portion into a plasma-treated surface, and in the step (ii), covering at least a portion of the plasma-treated surface with the exterior body.

[0007] Another aspect of the present disclosure relates to an electrolytic capacitor including a capacitor element including an anode portion and a cathode portion, lead terminals including an anode lead terminal electrically connected to the anode portion and a cathode lead terminal electrically connected to the cathode portion, and an exterior body including a resin and covering a portion of the lead terminal and the capacitor element, wherein at least a portion of a surface of the lead terminal in contact with the exterior body is a plasma-treated surface.

[0008] According to the present disclosure, a highly reliable electrolytic capacitor can be obtained.

[0009] Fig. 1 is a cross-sectional view schematically showing an example of a step in the manufacturing method of embodiment 1. Fig. 2 is a cross-sectional view schematically showing an example of a step subsequent to the step shown in Fig. 1 .

[0010] Before describing the embodiments, the problems in the prior art will be briefly described below.

[0011] Currently, there is a demand for further improvement in the reliability of electrolytic capacitors. In view of the above-mentioned problems, one of the objects of the present disclosure is to provide an electrolytic capacitor with higher reliability.

[0012] Below, embodiments 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 other materials may be applied as long as the invention according to the present disclosure can be implemented. 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 of numerical values ​​related to specific physical properties or conditions are exemplified, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined, as long as the lower limit is not equal to or greater than the upper limit.

[0013] (Method for Manufacturing Electrolytic Capacitor) A manufacturing method according to an embodiment of the present disclosure is a method for manufacturing an electrolytic capacitor including a capacitor element having an anode portion and a cathode portion. This manufacturing method may be referred to hereinafter as "manufacturing method (M)." Manufacturing method (M) includes steps (i) and (ii) in this order, and further includes a plasma treatment step. These steps are described below.

[0014] (Step (i)) Step (i) is a step of electrically connecting an anode lead terminal to an anode portion of a capacitor element and electrically connecting a cathode lead terminal to a cathode portion of a capacitor element. Hereinafter, the anode lead terminal and the cathode lead terminal may be collectively referred to as "lead terminals."

[0015] The method for connecting the lead terminal and the capacitor element is not particularly limited, and any known method may be used. For example, the anode lead terminal and the anode portion (e.g., an anode wire) may be connected by welding. The cathode lead terminal and the cathode portion may be connected by a conductive layer. The conductive layer may be formed using a metal paste (e.g., a silver paste) containing metal particles (e.g., silver particles) and a resin.

[0016] (Plasma Treatment Step) The plasma treatment step is performed before step (ii). For example, the plasma treatment step may be performed before step (i), or may be performed after step (i) and before step (ii). The plasma treatment step is a step of subjecting at least a portion of the metal surface of at least one lead terminal selected from the group consisting of an anode lead terminal and a cathode lead terminal to plasma treatment, thereby converting the at least portion into a plasma-treated surface. Hereinafter, the surface of the metal surface of the lead terminal that is subjected to plasma treatment may be referred to as the "treated surface."

[0017] Plasma treatment can make the treated surface hydrophilic and clean the treated surface. Making the treated surface hydrophilic makes it easier for the resin in the outer casing to adsorb to the treated surface. As a result, the adhesion of the outer casing to the treated surface can be improved. Furthermore, cleaning the treated surface to remove deposits (e.g., organic matter) present on the treated surface can improve the adhesion of the outer casing to the treated surface (lead terminal surface). Improving the adhesion between the outer casing and the lead terminal surface can prevent moisture and oxygen from penetrating from the outside through the surface of the lead terminal. As a result, long-term deterioration of the capacitor element can be suppressed, and the reliability of the electrolytic capacitor can be improved.

[0018] The conditions for the plasma treatment can be selected depending on the purpose, and known plasma treatment conditions may be adopted. When the surface to be treated is to be hydrophilized, for example, atmospheric pressure low-temperature plasma treatment may be used. By hydrophilizing the surface to be treated (metal surface) by plasma treatment, hydrophilic groups (e.g., hydroxyl groups, carbonyl groups, carboxyl groups, etc.) are introduced into the surface to be treated.

[0019] Atmospheric pressure low-temperature plasma treatment may be carried out under known conditions. The plasma gas for atmospheric pressure low-temperature plasma may be nitrogen gas, argon gas, hydrogen gas, helium gas, or oxygen gas, and these gases may be mixed with atmospheric components (e.g., oxygen gas, nitrogen gas, etc.). An example of atmospheric pressure low-temperature plasma treatment conditions is shown below.

[0020] Nitrogen gas pressure: 0.3 to 0.5 MPa Nitrogen gas flow rate: 20 to 30 L / min Irradiation distance: 5 to 30 mm Movement speed of plasma generation unit or workpiece (lead terminal): 10 to 50 mm / sec When cleaning the workpiece surface by plasma treatment, the plasma treatment may be performed under known plasma cleaning conditions.

[0021] When plasma treatment is performed after step (i), the plasma treatment is performed with the lead terminals connected to the capacitor element. When plasma treatment is performed before step (i), the plasma treatment may be performed on a metal sheet including portions that will become multiple lead terminals. The metal sheet to be plasma treated may be pre-punched and / or bent according to the shape of the lead terminals, or may be a metal sheet before such processing. By plasma treating the metal sheet, the surfaces of the portions that will become the lead terminals included therein become the plasma-treated surface. When plasma treating the metal sheet, only one side of the metal sheet may be plasma-treated, or both sides of the metal sheet may be plasma-treated.

[0022] (Step (ii)) Step (ii) is a step of covering a part of the anode lead terminal, a part of the cathode lead terminal, and the capacitor element with an exterior body containing a resin. In step (ii), at least a part of the plasma-treated surface is covered with the exterior body.

[0023] There are no particular limitations on step (ii), and a known method may be used. For example, the outer casing may be formed by a predetermined method (transfer molding, injection molding, etc.) using a resin composition that will become the outer casing.

[0024] An electrolytic capacitor is obtained by the step (ii). When a plurality of electrolytic capacitors are formed at once, the individual electrolytic capacitors are separated after the step (ii) as necessary.

[0025] Of the surfaces of the lead terminal, 30% or more, 50% or more, or 80% or more of the surface that comes into contact with the exterior body is preferably a plasma-treated surface. Of the surfaces of the lead terminal, the entire surface that comes into contact with the exterior body may be a plasma-treated surface.

[0026] In the manufacturing method (M), the following conditions (1) and (2) may be satisfied: (1) The resin contained in the outer casing includes at least one selected from the group consisting of an epoxy resin and a phenolic resin. For example, the resin contained in the outer casing may include an epoxy resin, a phenolic resin, or both. (2) In step (i), the plasma-treated surface is hydrophilized by plasma treatment.

[0027] Epoxy resins and phenolic resins are particularly susceptible to adsorption onto hydrophilized metal surfaces, and therefore, when conditions (1) and (2) are satisfied, the adhesion between the outer casing and the lead terminals can be particularly improved.

[0028] When the above condition (1) is satisfied, the proportion of the at least one resin in the outer casing may be 3% by mass or more, 5% by mass or more, or 10% by mass or more, or 100% by mass or less, 40% by mass or less, or 20% by mass or less. For example, the proportion may be in the range of 3% by mass to 40% by mass, 3% by mass to 20% by mass, or 5% by mass to 20% by mass.

[0029] When the above condition (2) is satisfied, for example, when the above conditions (1) and (2) are satisfied, it is preferable that the following condition (3) be satisfied. Urethane resins also tend to adsorb to hydrophilized metal surfaces. Therefore, when conditions (2) and (3) are satisfied, the adhesion between the conductive layer and the cathode lead terminal is improved, and contact resistance can be reduced. (3) In step (ii), the cathode lead terminal is connected to the cathode portion by a conductive layer containing metal particles and a resin containing at least one resin selected from the group consisting of epoxy resins, urethane resins, and phenolic resins. Furthermore, a portion of the plasma-treated surface comes into contact with the conductive layer.

[0030] When the above condition (3) is satisfied, the conductive layer may contain an epoxy resin, a urethane resin, a phenolic resin, two of them, or all three of them. When the above condition (3) is satisfied, the proportion of the at least one resin of the condition (3) in the conductive layer may be in the range of 1 mass % to 50 mass % (for example, in the range of 3 mass % to 20 mass %).

[0031] After the plasma treatment step, step (ii) is preferably performed within 72 hours, but may also be performed within 48 hours or 24 hours. When the plasma-treated surface is left in the atmosphere, its effect decreases over time. Therefore, it is preferable to perform step (ii) while the effect of the plasma-treated surface is still sufficiently obtained. If step (ii) is not performed within 72 hours after the plasma treatment, the lead terminal (e.g., a metal sheet including a portion that will become a lead terminal) that has undergone the plasma treatment step is preferably stored under reduced pressure and / or at a low temperature (e.g., 20°C or below). In this case, it is preferable to store a metal sheet including portions that will become multiple lead terminals in a stacked state.

[0032] The lead terminal may be composed of only a substrate, or may include a substrate and a metal layer (e.g., a plating layer) formed on the surface of the substrate. The metal surface to be subjected to the plasma treatment may include at least one selected from the group consisting of copper, gold, nickel, tin, lead, bismuth, silver, zinc, iron, chromium, and palladium.

[0033] The manufacturing method (M) may further include a step of roughening at least a portion of the surface of the lead terminal before step (i) and before the plasma treatment step. In this case, it is preferable to subject at least a portion of the roughened surface to plasma treatment in the plasma treatment step. This configuration can increase the area of ​​the surface to be plasma-treated. Furthermore, this configuration can provide an anchoring effect of the roughened surface. These effects can particularly improve the adhesion between the outer casing and the lead terminal.

[0034] The roughening method is not particularly limited, and may be a known method such as sandblasting or etching. Alternatively, the surface of the lead terminal may be roughened by irradiating the lead terminal with laser light (e.g., pulsed laser light).

[0035] (Electrolytic Capacitor) An electrolytic capacitor according to an embodiment of the present disclosure will be described below. This electrolytic capacitor may be referred to hereinafter as an "electrolytic capacitor (C)." The electrolytic capacitor (C) may be manufactured by a manufacturing method (M), although there are no limitations on the manufacturing method. The matters described for the manufacturing method (M) may also be applied to the electrolytic capacitor (C), and therefore, redundant explanations may be omitted. Furthermore, the matters described for the electrolytic capacitor (C) may also be applied to the manufacturing method (M).

[0036] The electrolytic capacitor (C) includes a capacitor element, lead terminals, and an exterior body. The capacitor element includes an anode portion and a cathode portion. The lead terminals include an anode lead terminal electrically connected to the anode portion and a cathode lead terminal electrically connected to the cathode portion. The exterior body covers a portion of the lead terminals and the capacitor element. The exterior body includes a resin. At least a portion of the surface of the lead terminal that is in contact with the exterior body is a plasma-treated surface that has been plasma-treated.

[0037] As explained in relation to the manufacturing method (M), the electrolytic capacitor (C) can improve the adhesion between the exterior body and the lead terminals, resulting in a highly reliable electrolytic capacitor with less degradation due to moisture, oxygen, etc.

[0038] The resin contained in the outer casing preferably includes at least one selected from the group consisting of epoxy resins and phenolic resins. In this case, the plasma-treated surface may have hydrophilic groups, and the resin of the outer casing (e.g., the at least one resin) may be adsorbed to the plasma-treated surface via the hydrophilic groups. As described above, this configuration can particularly improve adhesion between the outer casing and the lead terminals. Note that adsorption of the resin to the plasma-treated surface includes chemical adsorption and physical adsorption. Chemical adsorption is adsorption via chemical bonds, and includes, for example, cases in which hydrophilic groups formed on the plasma-treated surface react with the resin to form bonds.

[0039] As described above, the cathode lead terminal may be connected to the cathode part by a conductive layer containing metal particles and at least one resin selected from the group consisting of epoxy resin, urethane resin, and phenolic resin. In this case, the plasma-treated surface may have hydrophilic groups, and the resin of the conductive layer (e.g., the at least one resin) may be adsorbed to the plasma-treated surface via the hydrophilic groups.

[0040] As described above, at least a portion of the surface of the lead terminal may be roughened, or at least a portion of the plasma-treated surface may be roughened.

[0041] An example of the configuration and components of an electrolytic capacitor manufactured by manufacturing method (M) and an electrolytic capacitor (C) will be described below. The example electrolytic capacitor described below includes a capacitor element, an outer casing, an anode lead terminal, and a cathode lead terminal. Note that the configuration and components of the electrolytic capacitor manufactured by manufacturing method (M) and the electrolytic capacitor (C) are not limited to the following example.

[0042] (Capacitor Element) The capacitor element includes an anode part, a dielectric layer, and a cathode part. There are no particular limitations on the capacitor element, and a capacitor element used in a known solid electrolytic capacitor may be used.

[0043] The anode section includes an anode body and may further include an anode wire. The anode body may be a porous sintered body or a metal foil with a porous surface. A dielectric layer is formed on at least a portion of the surface of the anode body. The cathode section includes an electrolyte layer and a cathode extraction layer. The electrolyte layer is disposed between the dielectric layer formed on the surface of the anode body and the cathode extraction layer. These components are not particularly limited, and components used in known solid electrolytic capacitors may be applied. Examples of these components are described below.

[0044] (Anode Body) Valve metals can be used as the material for the anode body. Examples of valve metals that can be used include titanium (Ti), tantalum (Ta), niobium (Nb), aluminum (Al), and alloys containing these. The anode body may be formed by sintering particles of the material (e.g., particles of a valve metal) or by etching the material metal. The dielectric layer formed on the surface of the anode body may be formed by subjecting the surface of the anode body to a chemical conversion treatment. There are no limitations on the method of chemical conversion treatment, and known chemical conversion treatment methods may be applied.

[0045] (Anode Wire) When the anode body is a sintered body, the anode portion may include an anode wire. The anode wire may be a wire made of a metal. Examples of materials for the anode wire include the valve metals described above and copper. A portion of the anode wire is embedded in the anode body, and the remaining portion protrudes from the end face of the anode body.

[0046] (Electrolyte Layer) The electrolyte layer is not particularly limited, and an electrolyte layer used in a known solid electrolytic capacitor may be applied. In this specification, the term "electrolyte layer" may be read as a "solid electrolyte layer," and the term "electrolytic capacitor" may be read as a "solid electrolytic capacitor." The electrolyte layer may be a laminate of two or more different electrolyte layers.

[0047] The electrolyte layer is disposed so as to cover at least a portion of the dielectric layer. The electrolyte layer may be formed using a manganese compound or a conductive polymer. Examples of conductive polymers include polypyrrole, polythiophene, polyaniline, and derivatives thereof. These may be used alone or in combination. The conductive polymer may also be a copolymer of two or more types of monomers. Note that a derivative of a conductive polymer refers to a polymer having a conductive polymer as its basic skeleton. For example, an example of a polythiophene derivative is poly(3,4-ethylenedioxythiophene).

[0048] A dopant is preferably added to the conductive polymer. The dopant can be selected depending on the conductive polymer, and known dopants may be used. Examples of dopants include naphthalenesulfonic acid, p-toluenesulfonic acid, polystyrenesulfonic acid, and salts thereof. An example of an electrolyte layer is formed using poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrenesulfonic acid (PSS).

[0049] The electrolyte layer containing the conductive polymer may be formed by polymerizing a raw material monomer on the dielectric layer, or by applying a liquid containing the conductive polymer (and a dopant, if necessary) to the dielectric layer and then drying it.

[0050] (Cathode extraction layer) The cathode extraction layer is a conductive layer and is disposed so as to cover at least a portion of the electrolyte layer. The cathode extraction layer may include a carbon layer formed on the electrolyte layer and a metal paste layer formed on the carbon layer. The carbon layer may be formed of a conductive carbon material such as graphite and a resin. The metal paste layer may be formed of metal particles (e.g., silver particles) and a resin, for example, a known silver paste.

[0051] (Cathode Lead Terminal and Anode Lead Terminal) The cathode lead terminal includes a cathode terminal portion exposed on the bottom surface of the electrolytic capacitor and a connection portion connected to the cathode terminal portion. The connection portion is electrically connected to the cathode portion. For example, the connection portion may be connected to the cathode lead layer via a conductive layer (e.g., a silver paste layer) or the like. The anode lead terminal includes an anode terminal portion exposed on the bottom surface of the electrolytic capacitor and a wire connection portion connected to the anode terminal portion. The wire connection portion is connected to an anode wire. The lead terminal may be formed by processing a metal sheet (including a metal plate and a metal foil) made of a metal (e.g., copper, a copper alloy) using a known metal processing method. The thickness of the lead terminal is not particularly limited and may be in the range of 25 μm to 200 μm (e.g., 25 μm to 100 μm).

[0052] The lead terminal may include a substrate made of the above metal and a plating layer formed on the substrate. The plating layer may be formed by a known method. The plating layer may be formed of a metal (including alloys) such as nickel, gold, palladium, tin, or copper, and may include a nickel layer, a gold layer, a palladium layer, a tin layer, or a copper layer. For example, the plating layers may be stacked on the substrate in the following order: nickel layer, gold layer, and palladium layer.

[0053] (Exterior Body) The exterior body is disposed around the capacitor element so that the capacitor element is not exposed on the surface of the electrolytic capacitor. Furthermore, the exterior body is disposed so as to cover a portion of the anode lead frame and a portion of the cathode lead frame. The exterior body typically contains a resin (insulating resin) and an insulating filler.

[0054] The outer casing may be formed of a resin composition containing an insulating resin and an insulating filler (e.g., an inorganic filler). The resin composition may contain, in addition to the insulating resin and the insulating filler, a curing agent, a polymerization initiator, and / or a catalyst. Examples of insulating resins include epoxy resin, phenolic resin, urea resin, polyimide, polyamideimide, polyurethane, diallyl phthalate, unsaturated polyester, polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), and the like. The outer casing may contain one type of resin or two or more types of resins.

[0055] Examples of insulating fillers include insulating particles, insulating fibers, etc. Examples of insulating materials constituting the insulating filler include insulating compounds (oxides, etc.) such as silica and alumina, glass, and mineral materials (talc, mica, clay, etc.). The insulating filler contained in the outer casing may be one type or two or more types.

[0056] An example of the manufacturing method (M) and the electrolytic capacitor (C) will be specifically described below with reference to the drawings. The above-described configuration can be applied to the example of the method described below. The example of the method described below can be modified based on the above description. The matters described below may also be applied to the above-described embodiment. In the embodiment described below, components that are not essential to the manufacturing method and electrolytic capacitor of the present disclosure may be omitted. Note that, for ease of understanding, the following figures may show shapes that differ from the actual shapes.

[0057] Embodiment 1 In embodiment 1, an example of a manufacturing method according to the present disclosure will be described. In this manufacturing method, as shown in Fig. 1 , lead terminals 200 (anode lead terminal 210 and cathode lead terminal 220) are connected to a capacitor element 110. Specifically, an end of the anode lead terminal 210 is connected to the anode portion 111 of the capacitor element 110, and the cathode lead terminal 220 is connected to the cathode portion 115 of the capacitor element 110 (step (i)).

[0058] The anode lead terminal 210 is connected to an end of the anode wire 112 of the anode portion 111 by welding or the like. The cathode lead terminal 220 is connected to the cathode extraction layer 117 of the cathode portion 115 via the conductive layer 141. As shown in Fig. 2 , the plurality of lead terminals 200 may be formed by processing (punching or bending) a portion of the metal sheet M. The plurality of capacitor elements 110 are disposed on each of the plurality of lead terminals 200.

[0059] The capacitor element 110 includes an anode portion 111, a dielectric layer 114, and a cathode portion 115. The anode portion 111 includes an anode body 113 and an anode wire 112. The anode body 113 is a porous sintered body in the shape of a rectangular parallelepiped, and a dielectric layer 114 is formed on the surface. A portion of the anode wire 112 protrudes from one end face of the anode body 113 toward the front surface 100f of the electrolytic capacitor 100 (see FIG. 2 ). The other portion of the anode wire 112 is embedded in the anode body 113.

[0060] Cathode section 115 includes an electrolyte layer 116 disposed so as to cover at least a portion of dielectric layer 114, and a cathode extraction layer 117 formed on electrolyte layer 116. Cathode extraction layer 117 includes, for example, a carbon layer formed on electrolyte layer 116 and a metal particle layer formed on the carbon layer. The metal particle layer is, for example, a metal paste layer (e.g., a silver paste layer) formed using a metal paste.

[0061] The anode lead terminal 210 includes an anode terminal portion 211 and a wire connection portion 212. The anode terminal portion 211 is exposed on the bottom surface 100b of the electrolytic capacitor 100 (see FIG. 2 ). The wire connection portion 212 is connected to the anode wire 112. The cathode lead terminal 220 includes a cathode terminal portion 221 and a connection portion 222. The cathode terminal portion 221 is exposed on the bottom surface 100b of the electrolytic capacitor 100. The connection portion 222 is electrically connected to the cathode extraction layer 117 (cathode portion 115) by a conductive layer 141.

[0062] Next, the lead terminal 200 and capacitor element 110 in the state shown in FIG. 1 are subjected to the plasma treatment described above. The plasma treatment is performed with the bottom surface 100b facing the processing stage of the plasma processing apparatus. As a result, the surface 200a of the lead terminal 200 other than the portion on the bottom surface 100b side is exposed to plasma and becomes the plasma-treated surface (plasma-treated surface 200b in FIG. 2). Specifically, the surface that will come into contact with the outer casing in a later process can be the plasma-treated surface. In this case, the surface of the anode wire 112 can also be the plasma-treated surface. As a result, the adhesion between the anode wire 112 and the outer casing can be improved.

[0063] When plasma treatment is performed before connecting the lead terminal 200 to the capacitor element 110, first, only the lead terminal 200 is plasma treated. When plasma treating a metal sheet including portions that will become multiple lead terminals, the plasma treatment may be performed after processing a portion of the metal sheet into the shape of the lead terminal 200 (for example, the shape shown in FIG. 1), or may be performed before processing the shape. By performing plasma treatment after processing into the shape of the lead terminal, it is possible to make the entire portion of the lead terminal 200 that comes into contact with the exterior body into a plasma-treated surface in a single plasma treatment. After plasma treatment, the lead terminal 200 is connected to the capacitor element 110 as shown in FIG. 1.

[0064] Next, as shown in FIG. 2 , portions of the lead terminals 200 (portions of the anode lead terminal 210 and the cathode lead terminal 220) and the capacitor element 110 are covered with the exterior body 150. This causes the plasma-treated surfaces 200b of the lead terminals 200 to be covered with the exterior body 150. As a result, the above-described effects are obtained. After the exterior body 150 is formed, the plurality of electrolytic capacitors are individually separated as necessary. In this manner, the electrolytic capacitors are manufactured.

[0065] The present disclosure can be used for an electrolytic capacitor and a manufacturing method thereof.

[0066] 100: Electrolytic capacitor 110: Capacitor element 111: Anode portion 115: Cathode portion 141: Conductive layer 150: Outer casing 200: Lead terminal 200b: Plasma-treated surface 210: Anode lead terminal 220: Cathode lead terminal

Claims

1. A method for manufacturing an electrolytic capacitor including a capacitor element having an anode portion and a cathode portion, a step (i) of electrically connecting an anode lead terminal to the anode portion and a cathode lead terminal to the cathode portion, and a step (ii) of covering a part of the anode lead terminal, a part of the cathode lead terminal, and the capacitor element with an exterior body containing resin, in this order, further including a plasma treatment step of subjecting at least a part of the metal surface of at least one lead terminal selected from the group consisting of the anode lead terminal and the cathode lead terminal to plasma treatment before the step (ii), to make the at least a part a plasma-treated surface, A method for manufacturing an electrolytic capacitor, wherein in the step (ii), at least a part of the plasma-treated surface is covered with the exterior body.

2. The resin includes at least one selected from the group consisting of an epoxy resin and a phenol resin, In the step (i), the plasma treatment hydrophilizes the plasma-treated surface, according to the manufacturing method of Claim 1.

3. In the step (ii), the cathode lead terminal is connected to the cathode portion by a conductive layer including at least one resin selected from the group consisting of an epoxy resin, a urethane resin, and a phenol resin and metal particles, A part of the plasma-treated surface is in contact with the conductive layer, according to the manufacturing method of Claim 2.

4. After performing the plasma treatment step, the step (ii) is performed within 72 hours, according to the manufacturing method of Claim 1 or 2.

5. The metal surface includes at least one selected from the group consisting of copper, gold, nickel, tin, lead, bismuth, silver, zinc, iron, chromium, and palladium, according to the manufacturing method of Claim 1 or 2.

6. The plasma treatment step is performed before the step (i), according to the manufacturing method of Claim 1 or 2.

7. Before the step (i) and before the plasma treatment step, further including a step of roughening at least a part of the surface of the lead terminal, In the plasma treatment step, the plasma treatment is performed on at least a part of the roughened surface, according to the manufacturing method of Claim 1 or 2.

8. An electrolytic capacitor, comprising: a capacitor element including an anode portion and a cathode portion, A lead terminal including an anode lead terminal electrically connected to the anode portion and a cathode lead terminal electrically connected to the cathode portion; An exterior body covering a part of the lead terminal and the capacitor element, the exterior body including a resin; An electrolytic capacitor, wherein at least a part of the surface of the lead terminal that is in contact with the exterior body is a plasma-treated surface that has been plasma-treated.

9. The resin includes at least one selected from the group consisting of an epoxy resin and a phenol resin; The electrolytic capacitor according to claim 8, wherein the plasma-treated surface has a hydrophilic group, and the resin is adsorbed to the plasma-treated surface via the hydrophilic group.