WO2023074413A1

WO2023074413A1 - Anode body and manufacturing method thereof, and electrolytic capacitor and manufacturing method thereof

Info

Publication number: WO2023074413A1
Application number: PCT/JP2022/038410
Authority: WO
Inventors: 徳彦大形
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2021-10-28
Filing date: 2022-10-14
Publication date: 2023-05-04

Abstract

A method for manufacturing an anode body for an electrolytic capacitor includes a powder preparation step for preparing anode body powder 110 containing powder of a first metal that is a valve action metal, and a step for sintering the anode body powder to obtain an anode body. The powder of the first metal contains, in addition to the first metal, a small amount of particles containing a second metal having magnetism. The manufacturing method further includes a magnetic separation step for removing particles containing the second metal from the first metal powder by magnetic separation before sintering the anode body powder 110.

Description

Anode body and manufacturing method thereof, and electrolytic capacitor and manufacturing method thereof

The present disclosure relates to an anode body and its manufacturing method, and an electrolytic capacitor and its manufacturing method.

Electrolytic capacitors have a low equivalent series resistance (ESR) and excellent frequency characteristics, so they are installed in various electronic devices. Electrolytic capacitors typically comprise a capacitor element comprising an anode portion and a cathode portion. The anode part includes a porous anode body, and a dielectric layer is formed on the surface of the anode body. The dielectric layer contacts the electrolyte. As an electrolyte, there is an electrolytic capacitor using a solid electrolyte such as a conductive polymer (see, for example, Patent Document 1).

The anode body of an electrolytic capacitor is formed porous, for example, by putting valve metal powder into a mold and sintering it. As a method for preparing a metal powder used for an anode body, Patent Document 2 describes a method for preparing foil-like tantalum powder, in which a nitriding step at a low temperature of 500° C. or lower is followed by a high-temperature heat treatment step at 1000° C. or higher. Are listed.

JP 2009-182157 A JP 2019-527300 A

　Improve the reliability of electrolytic capacitors that use solid electrolytes.

One aspect of the present disclosure is a method of manufacturing an anode body for an electrolytic capacitor, comprising: a powder preparation step of preparing an anode body powder containing a powder of a first metal that is a valve action metal; and sintering to obtain an anode body, wherein the powder of the first metal contains particles containing a second metal having magnetism in addition to the first metal, and the powder for the anode body The present invention relates to a method for manufacturing an anode body, further comprising a magnetic separation step of removing particles containing the second metal from the powder of the first metal by magnetic separation before sintering the powder.

Another aspect of the present disclosure includes a capacitor element including a porous anode body, a dielectric layer formed on the surface of the anode body, and a solid electrolyte layer covering at least a portion of the dielectric layer. A method for manufacturing an electrolytic capacitor, comprising the steps of: preparing the anode body; covering at least a portion of the anode body with the dielectric layer; and a step of covering a portion of the electrolytic capacitor with the solid electrolyte layer.

Still another aspect of the present disclosure includes particles of a first metal that is a valve metal and particles of a second metal having magnetism, and the content of the second metal is 10 mg per 1 kg of the first metal. The following relates to anode bodies for electrolytic capacitors.

Yet another aspect of the present disclosure is a capacitor element including a porous anode body, a dielectric layer formed on the surface of the anode body, and a solid electrolyte layer covering at least a portion of the dielectric layer. wherein the anode body contains particles of a first metal that is a valve metal and particles of a second metal having magnetism, and the content ratio of the second metal in the anode body is It relates to an electrolytic capacitor that is 10 mg or less per 1 kg of the first metal.

According to the present disclosure, the reliability of electrolytic capacitors is improved.

While the novel features of the present invention are set forth in the appended claims, the present invention, both as to construction and content, together with other objects and features of the present invention, will be further developed by the following detailed description in conjunction with the drawings. will be well understood.

1 is a schematic configuration diagram showing an example of a magnetic separation device for separating particles containing a second metal from anode body powder. FIG. 1 is a cross-sectional view schematically showing an example of a capacitor element according to an embodiment of the present disclosure; FIG. 1 is a cross-sectional view schematically showing an electrolytic capacitor manufactured by a manufacturing method according to an embodiment of the present disclosure; FIG.

Hereinafter, embodiments of the present disclosure will be described with examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values, materials, etc. may be exemplified, but other numerical values, materials, etc. may be applied as long as the effects of the present disclosure can be obtained. In this specification, the description "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 relating to specific physical properties, conditions, etc. are exemplified, any of the illustrated lower limits and any of the illustrated upper limits can be arbitrarily combined as long as the lower limit is not greater than or equal to the upper limit. . When a plurality of materials are exemplified, one of them may be selected and used alone, or two or more may be used in combination.

In addition, the present disclosure encompasses a combination of matters described in two or more claims arbitrarily selected from the multiple claims described in the attached claims. In other words, as long as there is no technical contradiction, the matters described in two or more claims arbitrarily selected from the multiple claims described in the attached claims can be combined.

According to the present disclosure, one of the factors (modes) that cause poor reliability in electrolytic capacitors is a factor derived from a minute amount of metallic impurities contained in the anode body, and even if the amount of metallic impurities is extremely small, the failure will occur. Based on the knowledge that it can occur.

A method for manufacturing an anode body for an electrolytic capacitor according to an embodiment of the present disclosure is a method for manufacturing an anode body for an electrolytic capacitor, and prepares an anode body powder containing powder of a first metal that is a valve action metal. It has a powder preparation step and a step of sintering the anode body powder to obtain an anode body.

In addition to the first metal, the powder of the first metal contains a small amount of particles containing a second magnetic metal (for example, iron (Fe)). Usually, the particles containing the second metal are removed to some extent by the supplier of the anode body powder. For example, as described in Patent Document 2, the content of iron impurities in the anode body powder is at most about 20 ppm on a mass basis. However, it has been found that even such a low content of the second metal causes poor reliability.

If the particles containing the second metal are contained in the anode body, when the dielectric film is formed on the surface of the anode body by chemical conversion treatment, the current flows intensively in the particles containing the second metal, and the surrounding dielectric Body layer properties are reduced. In the vicinity of the particles containing the second metal, the dielectric layer may be thinned or not formed, resulting in poor insulation.

The second metal may be contained in the form of particles containing the second metal instead of being evenly distributed in each of the particles of the first metal constituting the main component of the anode body powder. In other words, the anode body powder is a mixed powder of particles of the first metal, which accounts for the majority, and particles containing a small amount of the second metal. Therefore, even if the content of the second metal in the anode body powder is small, if the necessary amount of the anode body powder is subdivided to produce a plurality of anode bodies, most of the anode bodies contain the second metal. Although substantially free, the second metal may be present in relatively high concentrations in certain anode bodies. As a result, among the manufactured electrolytic capacitors, the electrolytic capacitor manufactured using the anode body containing the second metal at a high concentration shows deterioration in performance due to defective formation of the dielectric layer.

Some of the electrolytic capacitors with chemical conversion defects can be removed in the initial defect detection process after manufacturing, but if the number of particles containing the second metal contained in the particles of the anode body powder is large, the production of electrolytic capacitors will be delayed. A yield will fall. In addition, some electrolytic capacitors that have passed through the initial failure detection process, which contain particles containing the second metal, show early deterioration in performance due to use, which contributes to reduced reliability. From the viewpoint of suppressing poor formation, the proportion of particles containing the second metal contained in the anode body of the electrolytic capacitor is preferably 10 ppm or less (that is, 10 mg or less per 1 kg of the first metal).

The anode body manufacturing method further includes a magnetic separation step of removing particles containing the second metal from the powder of the first metal by magnetic separation before sintering the powder for the anode body. This reduces the number of anode bodies containing particles containing the second metal. Therefore, by using the anode body produced by this method, the production yield of the electrolytic capacitor is improved, and a highly reliable electrolytic capacitor can be obtained.

In the step of removing the particles containing the second metal from the powder of the first metal, the ratio of the particles containing the second metal to the powder of the first metal is 10 mg or less (that is, 10 ppm or less) per 1 kg of the powder of the first metal. It is preferable to remove the particles containing the second metal by magnetic separation so that The ratio of particles containing the second metal to the powder of the first metal after the removal step is more preferably 5 mg or less (that is, 5 ppm or less) or 3 mg or less (that is, 3 ppm or less) with respect to 1 kg of the first metal powder.
About 10,000 anode bodies can be manufactured from 1 kg of the powder of the first metal, depending on the size of the anode body. When the ratio is 10 mg or less per 1 kg of the first metal powder, the number of particles containing the second metal contained in 1 kg of the first metal powder is, for example, 50 or less.

With the demand for miniaturization of electrolytic capacitors, as the size of the anode body is reduced, the percentage of particles containing the second metal in the entire anode body becomes relatively large, and the above-mentioned chemical conversion failure becomes apparent. Therefore, it is important to previously reduce the proportion of particles containing the second metal contained in the anode body powder.

Particles containing a second metal may contain a non-magnetic metal (excluding the first metal) in addition to the second metal. The particles containing the second metal can be particles of an alloy of the second metal and a non-magnetic metal. In this case, the ratio of the particles containing the second metal to the powder of the first metal is calculated based on not only the mass of the second metal but also the mass of the entire alloy in the particles.
The particles containing the second metal may include, for example, stainless steel (SUS) particles. In this case, the particles containing the second metal include iron (Fe), which is the second metal, and chromium (Cr).

The removal of the particles containing the second metal may be performed on the anode body powder before powder adjustment, or may be performed on the anode body powder after powder adjustment. When the agent is added, it is preferable to add the agent to the anode body powder after powder conditioning, as will be described later.

The powder preparation step may be a step of mixing the powder of the first metal with a binder and stirring to prepare the powder for the anode body. By molding and sintering the anode body powder containing the binder, the sinterability of the anode body is good and the quality of the porous anode body can be improved. In this case, the particles containing the second metal may be removed from the anode body powder containing the binder after the powder preparation step.

In the powder adjusting step, the powder for the anode body can be prepared by putting the powder of the first metal and the binder in a container and shaking them. At this time, the inner surface of the container may be scraped by colliding with the particles of the first metal, and the particles of the metal forming the container may be mixed with the powder of the first metal. For example, if the container is made of stainless steel, particles containing metals such as iron (Fe), chromium (Cr), nickel (Ni), etc. may be mixed with the powder of the first metal. In particular, when the first metal contains tantalum (Ta), since the tantalum particles are hard, the inner surface of the container is likely to be scraped by the collision of the tantalum particles. It is easily mixed with the powder for the anode body.

Therefore, by providing a magnetic separation step for removing the particles containing the second metal from the anode body powder after the powder preparation process, the number of anode bodies containing particles containing the second metal is reduced, and the yield of electrolytic capacitor production is increased. and a highly reliable electrolytic capacitor can be obtained.

The first metal includes, for example, tantalum (Ta). The second metal may include, for example, at least one selected from the group consisting of iron (Fe) and nickel (Ni).

A magnetic sieve may be used to remove particles containing the second metal. By passing the anode body powder through the sieve, the particles of the first metal pass through the sieve while the particles containing the second metal adhere to the sieve. Therefore, the particles containing the second metal can be separated and removed from the anode body powder. The anode body powder may be passed through the sieve while vibrating the sieve horizontally and/or vertically. In order to avoid separation and removal of the particles of the anode body powder in a state of agglomerated large particles, the anode body powder passing side (the side opposite to the side where the anode body powder is fed) is moved toward the sieve. A gas stream may be supplied. The anode body powder may be passed through multiple sieves. For example, the step of passing the anode body powder through a magnetic sieve may be performed multiple times.

As another example, the belt conveyor shown in Fig. 1 may be used. However, the method for separating particles containing the second metal is not limited to the method using a sieve and the method using a belt conveyor.

In the example shown in FIG. 1 , the magnetic separation device 100 includes a belt 101 and a belt conveyor 103 having magnetic rollers 102 . The anode body powder 110 placed on the belt 101 is conveyed on the belt 101 toward the side of the magnetic roller 102 while being flattened to a uniform thickness by the doctor blade 104, and reaches the end of the magnetic roller 102 ( For example, it falls at position P) in FIG. At this time, the particles containing the second metal are attracted by the magnetic force of the magnetic roller 102 and oppose the downward gravitational force. (for example, position Q in FIG. 1). Thereby, the particles containing the second metal can be separated from the anode body powder.

An anode body according to an embodiment of the present disclosure includes particles of a first metal that is a valve metal and particles of a second metal having magnetism, and the content of the second metal is 10 mg or less. In other words, the content of the second metal is 100×(10/1000000)% by mass or less (0.001% by mass or less).

A method for manufacturing an electrolytic capacitor according to an embodiment of the present disclosure includes a porous anode body, a dielectric layer formed on the surface of the anode body, and a solid electrolyte layer covering at least a portion of the dielectric layer. A method of manufacturing an electrolytic capacitor comprising a capacitor element comprising: providing an anode body; covering at least a portion of the anode body with a dielectric layer; and a covering step. In the step of preparing the anode body, the anode body manufactured by the method for manufacturing the anode body is prepared.

An electrolytic capacitor according to an embodiment of the present disclosure is a capacitor element including a porous anode body, a dielectric layer formed on the surface of the anode body, and a solid electrolyte layer covering at least a portion of the dielectric layer. Prepare. The anode body contains particles of a first metal, which is a valve metal, and a small amount of particles containing a second metal having magnetism other than the first metal. The content of the second metal in the anode body is 10 mg or less or 0.001% by mass or less per 1 kg of the first metal. The content ratio of the second metal in the anode body can be calculated by, for example, an elemental analysis method such as ICP emission spectroscopy.

A method for manufacturing an anode body and a method for manufacturing an electrolytic capacitor according to the present embodiment will be described below with reference to the drawings as appropriate. However, the invention is not limited to this. FIG. 2 is a cross-sectional view schematically showing an example of the capacitor element according to this embodiment. FIG. 3 is a schematic cross-sectional view of an electrolytic capacitor manufactured by the manufacturing method according to this embodiment.

Electrolytic capacitor 20 is electrically connected to capacitor element 10 having anode portion 6 and cathode portion 7, exterior body 11 that seals capacitor element 10, and anode section 6, and a portion of exterior body 11 extends from An exposed anode lead terminal 13 and a cathode lead terminal 14 electrically connected to the cathode section 7 and partly exposed from the exterior body 11 are provided. Anode section 6 has anode body 1 and anode wire 2 . A dielectric layer 3 is formed on the surface of the anode body. Cathode portion 7 has solid electrolyte layer 4 covering at least a portion of dielectric layer 3 and cathode layer 5 covering the surface of solid electrolyte layer 4 .

<Capacitor element>
Hereinafter, capacitor element 10 will be described in detail, taking as an example a case in which a solid electrolyte layer is provided as an electrolyte.

Anode section 6 has anode body 1 and anode wire 2 extending from one surface of anode body 1 and electrically connected to anode lead terminal 13 .
Anode body 1 is, for example, a cuboid porous sintered body obtained by sintering particles of a first metal. As the particles of the first metal, particles of valve action metal such as titanium (Ti), tantalum (Ta), niobium (Nb) are used. Particles of one or more first metals are used in anode body 1 . The particles of the first metal may be an alloy of two or more metals. At least one of the two or more metals is the first metal. For example, an alloy containing a valve action metal (first metal) and silicon, vanadium, boron, or the like can be used. A compound containing a valve action metal and a typical element such as nitrogen may also be used. The alloy of the valve action metal is mainly composed of the valve action metal (first metal), and contains, for example, 50 atomic % or more of the valve action metal (first metal).

The anode wire 2 is made of a conductive material. The material of the anode wire 2 is not particularly limited, and examples thereof include the above-described valve action metals, copper, aluminum, aluminum alloys, and the like. The materials constituting anode body 1 and anode wire 2 may be of the same type or of different types. Anode wire 2 has a first portion 2 a embedded inside anode body 1 from one surface of anode body 1 and a second portion 2 b extending from the one surface of anode body 1 . The cross-sectional shape of the anode wire 2 is not particularly limited, and may be circular, track-shaped (a shape consisting of mutually parallel straight lines and two curved lines connecting the ends of these straight lines), elliptical, rectangular, polygonal, and the like. be done.

The anode portion 6 is produced, for example, by embedding the first portion 2a in the powder of the first metal particles, molding the first portion 2a into a rectangular parallelepiped shape, and sintering the first portion. As a result, the second portion 2b of the anode wire 2 is pulled out from one surface of the anode body 1 so as to be erected. The second portion 2b is joined to the anode lead terminal 13 by welding or the like, so that the anode wire 2 and the anode lead terminal 13 are electrically connected. The welding method is not particularly limited, and includes resistance welding, laser welding, and the like. After that, the corners of the rectangular parallelepiped can be processed to form curved surfaces.

A dielectric layer 3 is formed on the surface of the anode body 1 . The dielectric layer 3 is made of metal oxide, for example. As a method for forming a layer containing a metal oxide on the surface of anode body 1, for example, anode body 1 is immersed in a chemical solution to anodize the surface of anode body 1, or anode body 1 is immersed in oxygen. A method of heating in an atmosphere containing The dielectric layer 3 is not limited to the layer containing the above-mentioned metal oxide, and may have insulating properties.

(cathode)
The cathode section 7 has a solid electrolyte layer 4 and a cathode layer 5 covering the solid electrolyte layer 4 . Solid electrolyte layer 4 is formed to cover at least a portion of dielectric layer 3 .

For example, a manganese compound or a conductive polymer is used for the solid electrolyte layer 4 . Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and the like. These may be used alone, or may be used in combination. Also, the conductive polymer may be a copolymer of two or more monomers. Polythiophene, polyaniline, and polypyrrole may be used from the viewpoint of excellent conductivity. In particular, polypyrrole may be used because of its excellent water repellency.

The solid electrolyte layer 4 containing the conductive polymer is formed, for example, by polymerizing raw material monomers on the dielectric layer 3 . Alternatively, it is formed by coating the dielectric layer 3 with a liquid containing the conductive polymer. The solid electrolyte layer 4 is composed of one or more solid electrolyte layers. When the solid electrolyte layer 4 is composed of two or more layers, the composition and formation method (polymerization method) of the conductive polymer used for each layer may be different.

In this specification, polypyrrole, polythiophene, polyfuran, polyaniline, etc. mean polymers having polypyrrole, polythiophene, polyfuran, polyaniline, etc. as a basic skeleton, respectively. Therefore, polypyrrole, polythiophene, polyfuran, polyaniline, etc. may also include their respective derivatives. For example, polythiophenes include poly(3,4-ethylenedioxythiophene) and the like.

Various dopants may be added to the polymerization liquid, solution or dispersion of the conductive polymer for forming the conductive polymer, in order to improve the conductivity of the conductive polymer. Although the dopant is not particularly limited, naphthalenesulfonic acid, p-toluenesulfonic acid, polystyrenesulfonic acid and the like can be mentioned, for example.

When the conductive polymer is dispersed in the dispersion medium in the form of particles, the average particle diameter D50 of the particles is, for example, 0.01 μm or more and 0.5 μm or less. If the average particle size D50 of the particles is within this range, the particles can easily penetrate into the anode body 1 .

The cathode layer 5 has, for example, a carbon layer 5a formed to cover the solid electrolyte layer 4 and a metal paste layer 5b formed on the surface of the carbon layer 5a. The carbon layer 5a contains a conductive carbon material such as graphite and a resin. The metal paste layer 5b contains, for example, metal particles (for example, silver) and resin. In addition, the structure of the cathode layer 5 is not limited to this structure. The configuration of the cathode layer 5 may be any configuration as long as it has a current collecting function.

<Anode lead terminal>
Anode lead terminal 13 is electrically connected to anode body 1 through second portion 2 b of anode wire 2 . The material of anode lead terminal 13 is not particularly limited as long as it is electrochemically and chemically stable and has conductivity. The anode lead terminal 13 may be made of metal such as copper, or may be made of non-metal. The shape is not particularly limited as long as it is flat. The thickness of anode lead terminal 13 (the distance between the main surfaces of anode lead terminal 13) may be 25 μm or more and 200 μm or less, and may be 25 μm or more and 100 μm or less, from the viewpoint of height reduction.

One end of the anode lead terminal 13 may be joined to the anode wire 2 with a conductive adhesive or solder, or may be joined to the anode wire 2 by resistance welding or laser welding. The other end of anode lead terminal 13 is led out of package 11 and exposed from package 11 . The conductive adhesive is, for example, a mixture of a thermosetting resin, which will be described later, and carbon particles or metal particles.

<Cathode lead terminal>
The cathode lead terminal 14 is electrically connected to the cathode portion 7 at the joint portion 14a. When the cathode layer 5 and the cathode lead terminal 14 joined to the cathode layer 5 are viewed from the normal direction of the cathode layer 5 , the junction portion 14 a is a portion where the cathode lead terminal 14 overlaps the cathode layer 5 .

The cathode lead terminal 14 is joined to the cathode layer 5 via a conductive adhesive 8, for example. One end of the cathode lead terminal 14 constitutes, for example, a part of the joint portion 14 a and is arranged inside the exterior body 11 . The other end of the cathode lead terminal 14 is led out to the outside. Therefore, a portion including the other end of cathode lead terminal 14 is exposed from exterior body 11 .

The material of the cathode lead terminal 14 is also not particularly limited as long as it is electrochemically and chemically stable and has conductivity. The cathode lead terminal 14 may be made of metal such as copper, or may be made of non-metal. The shape is not particularly limited, either, and for example, it is long and flat. The thickness of the cathode lead terminal 14 may be 25 μm or more and 200 μm or less, or may be 25 μm or more and 100 μm or less, from the viewpoint of height reduction.

<Exterior body>
The exterior body 11 is provided to electrically insulate the anode lead terminal 13 and the cathode lead terminal 14, and is made of an insulating material (sheath material). The exterior body material includes, for example, thermosetting resin. Examples of thermosetting resins include epoxy resins, phenol resins, silicone resins, melamine resins, urea resins, alkyd resins, polyurethanes, polyimides, unsaturated polyesters, and the like.

≪Manufacturing method of electrolytic capacitor≫
An example of the method for manufacturing the electrolytic capacitor according to this embodiment will be described below.

(1) Anode Body Preparing Step First, an anode body is prepared. The anode body is manufactured by a manufacturing method including a powder preparation step of preparing an anode body powder containing a powder of a first metal that is a valve metal, and a step of sintering the anode body powder to obtain an anode body. be done.

In the powder adjustment process, for example, the powder of the first metal is placed in a shaker and stirred to obtain powder for the anode body.

The binder may be put into a shaker together with the powder of the first metal to adjust the powder for the anode body. This improves the fluidity of the anode body powder and improves the moldability. Further, in the sintering process, the particles are strongly bonded to form fine pores. A polyacryl carbonate etc. are mentioned as a binder. The binder may be mixed with the first metal powder in the form of a solution or dispersed dispersion in a solvent such as butanol or methanol.

Subsequently, the anode body powder and the anode wire 2 are put into a mold so that the first portion 2a is embedded in the anode body powder, and pressure-molded. After that, by sintering the molded body, the anode part 6 including the anode body 1, which is a porous sintered body of the first metal, is obtained. A first portion 2a of the anode wire is embedded inside the porous sintered body from one side thereof. The pressure during pressure molding is not particularly limited. Sintering is preferably performed under reduced pressure. The temperature during sintering is a high temperature of, for example, 1200.degree. C. to 1400.degree. Organic components such as binders and solvents contained in the anode body powder are removed by the high temperature during sintering. Prior to sintering, heat treatment at a relatively low temperature, eg, 300° C. to 500° C., may be performed to remove the binder. By sintering, the surfaces of the particles of the first metal are melted, and the particles of the first metal and the particles of the first metal and the first portion 2a of the anode wire are bonded to each other while maintaining gaps between the particles of the first metal. Electrically connected by bonding.

The particles of the first metal usually contain a small amount of particles of the second metal having magnetism. If the anode body after sintering contains particles of the second metal, the formation of the dielectric layer by subsequent chemical conversion treatment may be insufficient, and the reliability of the electrolytic capacitor may decrease. Therefore, before pressure molding, a separate magnetic separation step is performed to remove the particles containing the second metal from the particles of the first metal. In the magnetic separation step, as described above, the particles containing the second metal may be removed using a magnetic sieve, or the particles containing the second metal may be removed using the belt conveyor shown in FIG. The removing method is not limited to these methods.

The removal of particles containing the second metal may be performed before the powder adjustment process or after the powder adjustment process. However, in the powder preparation step, the powder of the first metal is put into a shaker and stirred to obtain the powder for the anode body. may be scraped off by the powder and mixed into the powder for the anode body. For example, when the container is made of stainless steel (SUS), the anode body powder may contain particles containing metals such as iron, chromium, and nickel. The magnetic separation step is preferably carried out after the powder adjustment step in that the magnetic metal particles originating from the container of the shaker can be removed.

The powder for the anode body is usually pressure-molded and sintered using a mold with a rectangular parallelepiped internal space. In this case, the shape of anode body 1 after sintering is also a rectangular parallelepiped.

(2) Step of Forming Dielectric Layer Next, anode body 1 is subjected to chemical conversion treatment, and at least a portion of anode body 1 is covered with dielectric layer 3 . Specifically, the anode body 1 is immersed in an anodizing tank filled with an electrolytic aqueous solution (for example, a phosphoric acid aqueous solution), the second portion 2b of the anode wire 2 is connected to the anode body in the anodizing tank, and anodization is performed. can form the dielectric layer 3 made of an oxide film of the valve action metal on the surface of the porous portion. The electrolytic aqueous solution is not limited to the phosphoric acid aqueous solution, and nitric acid, acetic acid, sulfuric acid, or the like can be used.

(3) Step of Forming Solid Electrolyte Layer Subsequently, at least part of the dielectric layer 3 is covered with the solid electrolyte layer 4 . Capacitor element 10 including anode body 1 , dielectric layer 3 , and solid electrolyte layer 4 is thus obtained.
The solid electrolyte layer 4 containing a conductive polymer is produced by, for example, impregnating the anode body 1 on which the dielectric layer 3 is formed with a monomer or oligomer, and then polymerizing the monomer or oligomer by chemical polymerization or electrolytic polymerization. Alternatively, anode body 1 having dielectric layer 3 formed thereon is impregnated with a solution or dispersion of a conductive polymer, followed by drying to form at least part of dielectric layer 3 .

The solid electrolyte layer 4 can be formed, for example, by impregnating the anode body 1 with the dielectric layer 3 formed thereon in a dispersion liquid containing a conductive polymer, a binder, and a dispersion medium, taking it out, and drying it. The dispersion may include a binder and/or conductive inorganic particles (eg, a conductive carbon material such as carbon black). Also, the conductive polymer may contain a dopant. The conductive polymer and dopant may be selected from those exemplified for the solid electrolyte layer 4, respectively. A known binder can be used. The dispersion may contain known additives used in forming the solid electrolyte layer.

Subsequently, a carbon paste and a metal paste are sequentially applied to the surface of the solid electrolyte layer 4 to form the cathode layer 5 composed of the carbon layer 5a and the metal paste layer 5b. The configuration of the cathode layer 5 is not limited to this, as long as it has a current collecting function.

Next, the anode lead terminal 13 and the cathode lead terminal 14 are prepared. A second portion 2b of anode wire 2 erected from anode body 1 is joined to anode lead terminal 13 by laser welding, resistance welding, or the like. After the conductive adhesive 8 is applied to the cathode layer 5 , the cathode lead terminal 14 is joined to the cathode portion 7 via the conductive adhesive 8 .

Subsequently, the materials of capacitor element 10 and exterior body 11 (for example, uncured thermosetting resin and filler) are placed in a mold, and capacitor element 10 is sealed by transfer molding, compression molding, or the like. At this time, the anode lead terminal 13 and the cathode lead terminal 14 are partly exposed from the mold. The molding conditions are not particularly limited, and the time and temperature conditions may be appropriately set in consideration of the curing temperature of the thermosetting resin used.

Finally, the exposed portions of anode lead terminal 13 and cathode lead terminal 14 are bent along exterior body 11 to form bent portions. As a result, a part of anode lead terminal 13 and cathode lead terminal 14 is arranged on the mounting surface of package 11 .
The electrolytic capacitor 20 is manufactured by the above method.

The present disclosure can be used for electrolytic capacitors, and preferably for electrolytic capacitors using a porous body as an anode body.

Although the present invention has been described in terms of its presently preferred embodiments, such disclosure should not be construed as limiting. Various alterations and modifications will no doubt become apparent to those skilled in the art to which the invention pertains after reading the above disclosure. Therefore, the appended claims are to be interpreted as covering all variations and modifications without departing from the true spirit and scope of the invention.

20: Electrolytic capacitor 10: Capacitor element 1: Anode body 2: Anode wire 2a: First part 2b: Second part 3: Dielectric layer 4: Solid electrolyte layer 5: Cathode layer 5a: Carbon layer 5b: Metal paste layer 6: Anode part 7: Cathode part 8: Conductive adhesive 11: Exterior body 13: Anode lead terminal 14: Cathode lead terminal 14a: Joint part 100: Magnetic separator 103: Belt conveyor 101: Belt 102: Magnetic roller 104: Doctor blade 110: Powder for anode body

Claims

A method of manufacturing an anode body for an electrolytic capacitor, comprising:
a powder preparation step of preparing an anode body powder containing a powder of a first metal that is a valve action metal;
a step of sintering the anode body powder to obtain an anode body,
The powder of the first metal contains particles containing a second metal having magnetism in addition to the first metal,
The method for manufacturing an anode body, further comprising a magnetic separation step of removing particles containing the second metal from the powder of the first metal by magnetic separation before sintering the powder for an anode body.
In the magnetic separation step, the particles containing the second metal are separated by magnetic separation so that the ratio of the particles containing the second metal to the powder of the first metal is 10 mg or less per 1 kg of the powder of the first metal. 2. The method for manufacturing an anode body according to claim 1, which is a step of removing.
The powder preparation step is a step of mixing a binder with the powder of the first metal and stirring the mixture to prepare the powder for the anode body,
3. The method for manufacturing an anode body according to claim 1, wherein said magnetic separation step is performed on said anode body powder containing said binder after said powder adjustment step.
The method for manufacturing an anode body according to any one of claims 1 to 3, wherein the magnetic separation step includes removing particles containing the second metal using a magnetic sieve.
The method for producing an anode body according to any one of claims 1 to 3, wherein the magnetic separation step includes removing particles containing the second metal using a belt conveyor having magnetic rollers.
the first metal includes tantalum,
6. The method for producing an anode body according to claim 1, wherein said second metal includes at least one selected from the group consisting of iron and nickel.
A method of manufacturing an electrolytic capacitor comprising a capacitor element including a porous anode body, a dielectric layer formed on the surface of the anode body, and a solid electrolyte layer covering at least a portion of the dielectric layer. hand,
a step of preparing the anode body by the anode body manufacturing method according to any one of claims 1 to 6;
covering at least a portion of the anode body with the dielectric layer;
and a step of covering at least part of the dielectric layer with the solid electrolyte layer.
Containing particles of a first metal that is a valve action metal and particles of a second metal having magnetism,
An anode body for an electrolytic capacitor, wherein the content of the second metal is 10 mg or less per 1 kg of the first metal.
the first metal includes tantalum,
9. The anode body for an electrolytic capacitor according to claim 8, wherein said second metal includes at least one selected from the group consisting of iron and nickel.
An electrolytic capacitor comprising a capacitor element including a porous anode body, a dielectric layer formed on the surface of the anode body, and a solid electrolyte layer covering at least a portion of the dielectric layer,
The anode body contains particles of a first metal that is a valve metal and particles of a second metal having magnetism, and the content of the second metal in the anode body is 10 mg per 1 kg of the first metal. The following are electrolytic capacitors.