JP2022099091A - Solid electrolytic capacitor - Google Patents

Abstract

To provide a high characteristic solid electrolytic capacitor.SOLUTION: The disclosed solid electrolytic capacitor includes: multiple capacitor elements 100; an anode lead terminal 21 and a cathode lead terminal 31 electrically connected to the capacitor element 100; and an exterior 40. Multiple capacitor elements 100 are laminated in the direction Ds connecting a lower surface 40b and an upper surface 40t. The configuration of at least one first capacitor element that is selected from a group including a capacitor element 100 closest to the lower surface 40b, a capacitor element 100 closest to the upper surface 40t, and a capacitor element 100 in which the area of the part connected to the cathode lead terminal 31 without going through another capacitor element 100 is the largest, is different from the configuration of second capacitor elements which are capacitor elements other than the first capacitor elements.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to solid electrolytic capacitors.

The solid electrolytic capacitor includes a capacitor element including a solid electrolyte layer, a lead terminal electrically connected to the capacitor element, and an exterior body for sealing the capacitor element.

Patent Document 1 (Patent No. 6702427) states that "a solid electrolytic capacitor including a plurality of capacitor elements stacked in parallel and an exterior resin for encapsulating the plurality of capacitor elements, wherein the plurality of capacitor elements are Each of the plurality of capacitors has a valve acting metal substrate, a dielectric layer made of an oxide film provided on the surface of the valve acting metal substrate, and a cathode layer provided on the surface of the dielectric layer. The solid electrolytic capacitor, characterized in that the oxide film of at least one capacitor element among the elements is thicker than the oxide film of another capacitor element. "

Patent No. 6702427

At present, there is a demand for further improvement in the characteristics of solid electrolytic capacitors. In such a situation, one of the purposes of the present disclosure is to provide a solid electrolytic capacitor having high characteristics.

One aspect of the disclosure relates to solid electrolytic capacitors. The solid electrolytic capacitor is an exterior body that seals a plurality of capacitor elements, an anode lead terminal and a cathode lead terminal electrically connected to the plurality of capacitor elements, and the plurality of capacitor elements, and is an exterior resin. An exterior body including, and a solid electrolytic capacitor including the anode lead terminal and the cathode lead terminal, respectively, including an anode terminal portion and a cathode terminal portion exposed on the lower surface of the exterior body, and the exterior body includes the cathode terminal portion. The plurality of capacitor elements have an upper surface opposite to the lower surface, and the plurality of capacitor elements are laminated in a direction connecting the lower surface and the upper surface, and the capacitor element closest to the lower surface and the capacitor element closest to the upper surface. The configuration of at least one first capacitor element selected from the group consisting of the capacitor element and the capacitor element having the largest area of the portion connected to the cathode lead terminal without passing through the other capacitor element The configuration is different from that of the second capacitor element, which is the capacitor element other than the first capacitor element.

According to the present disclosure, a solid electrolytic capacitor having high characteristics can be obtained.

It is sectional drawing which shows typically the example of the solid electrolytic capacitor of an embodiment. It is sectional drawing which shows typically an example of the capacitor element used for the solid electrolytic capacitor of an embodiment. It is sectional drawing which shows typically another example of the capacitor element used for the solid electrolytic capacitor of an embodiment. It is sectional drawing which shows the other example of the solid electrolytic capacitor of embodiment schematically.

Hereinafter, an example of the embodiment of the present disclosure will be described. In the following description, embodiments of the present disclosure will be described with reference to 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 effects of the present disclosure can be obtained. In this specification, when the term "numerical value A to numerical value B" is used, the range includes the numerical value A and the numerical value B.

(Solid electrolytic capacitor)
The solid electrolytic capacitor according to the present embodiment is an exterior body that seals a plurality of capacitor elements, an anode lead terminal and a cathode lead terminal electrically connected to the plurality of capacitor elements, and a plurality of capacitor elements. Includes an exterior body containing resin and. The anode lead terminal and the cathode lead terminal include an anode terminal portion and a cathode terminal portion exposed on the lower surface of the exterior body, respectively. The exterior body has an upper surface opposite to the lower surface. Hereinafter, the lower surface and the upper surface of the exterior body may be referred to as “lower surface (B)” and “upper surface (T)”, respectively.

The plurality of capacitor elements are laminated in the direction connecting the lower surface (B) and the upper surface (T). From the group consisting of the capacitor element closest to the bottom surface (B), the capacitor element closest to the top surface (T), and the capacitor element having the largest area connected to the cathode lead terminal without going through another capacitor element. The configuration of at least one first capacitor element selected is different from the configuration of the second capacitor element, which is a capacitor element other than the first capacitor element.

"The area of the portion connected to the cathode lead terminal (hereinafter, may be referred to as" partial X ") without passing through another capacitor element" means that the capacitor element (specifically, the cathode portion) is the cathode lead. When it is in direct contact with the terminal, it means the area of the portion of the capacitor element that is in contact with the cathode lead terminal. When the capacitor element is connected to the cathode lead terminal by a conductive member (eg, a conductive adhesive layer), the portion X is a region where the conductive member is in contact with both the capacitor element and the cathode lead terminal. Means the contact area between the capacitor element and the conductive member in the above.

The first capacitor element may differ from the second capacitor element in terms of structure. For example, the thickness of the specific layer constituting the first capacitor element may be thicker than the thickness of the layer in the second capacitor element. Alternatively, the first capacitor element may be different from the second capacitor element in terms of the composition of the constituent members. For example, the composition of the specific layer constituting the first capacitor element may be different from the composition of the layer in the second capacitor element.

In the first example (E1) of the solid electrolytic capacitor of the present embodiment, the first capacitor element is a capacitor element having the largest area of a portion connected to the cathode lead terminal without going through another capacitor element. .. In the second example (E2) of the solid electrolytic capacitor of the present embodiment, the first capacitor element is the capacitor element closest to the lower surface (B) and / or the capacitor element closest to the upper surface (T). The capacitor element having the largest area connected to the cathode lead terminal without going through another capacitor element is the capacitor element closest to the lower surface (B) or the capacitor element closest to the upper surface (T). May be.

Intrusion of oxygen and moisture from the outside tends to occur through the interface between the lead terminal and the exterior resin. Therefore, it is particularly important to suppress the intrusion of oxygen and moisture in the capacitor element having the largest area of the portion connected to the cathode lead terminal without passing through the capacitor element. Since the capacitor element closest to the lower surface (B) and the capacitor element closest to the upper surface (T) are also close to the outside, they are easily affected by the intrusion of oxygen and moisture from the outside. Therefore, it is particularly important to suppress the invasion of oxygen and moisture even in these devices. Therefore, by setting the configuration of the first capacitor element to have a higher barrier property than the configuration of the other capacitor elements, the influence of the intrusion of oxygen and moisture can be efficiently reduced. As a result, deterioration of long-term characteristics of the solid electrolytic capacitor can be suppressed, and reliability can be improved. Further, by making only the capacitor element of the portion easily affected by the intrusion of oxygen or moisture a special configuration, it is possible to suppress an increase in the manufacturing cost of the solid electrolytic capacitor.

As an example of the solid electrolytic capacitor of the present embodiment, the first to fifth solid electrolytic capacitors will be described. Unless otherwise specified, the following first to fifth solid electrolytic capacitors may be the solid electrolytic capacitors of the first example (E1) or the solid of the second example (E2). It may be an electrolytic capacitor.

(First solid electrolytic capacitor)
In the first solid electrolytic capacitor, the thickness of the first capacitor element is thicker than the thickness of the second capacitor element. The first solid electrolytic capacitor may be the first example (E1) described above or the second example (E2). Since the first capacitor element of the second example (E2) is closer to the surface of the exterior body than the other capacitor elements, it is easily affected by oxygen gas and moisture that have entered from the outside of the capacitor. Therefore, by making the first capacitor element thicker, it is possible to suppress deterioration of the characteristics of the first and second capacitor elements due to the intrusion of oxygen gas and water. According to the first solid electrolytic capacitor, it is possible to suppress the deterioration of the characteristics due to the intrusion of oxygen gas and water. The thickness of the capacitor element is the maximum thickness of the capacitor element in the direction connecting the lower surface (B) and the upper surface (T).

In the first solid electrolytic capacitor, the thickness of the first capacitor element is larger than 1 times the thickness of the second capacitor element, and may be 1.1 times or more or 1.2 times or more. The thickness of the first capacitor element may be 1.5 times or less the thickness of the second capacitor element, or may be 1.3 times or less. These lower and upper limits can be combined arbitrarily.

(Second solid electrolytic capacitor)
In the second solid electrolytic capacitor, each of the plurality of capacitor elements includes a cathode extraction layer. The average thickness of the cathode extraction layer of the first capacitor element is thicker than the average thickness of the cathode extraction layer of the second capacitor element. The first capacitor element may be thicker than the second capacitor element due to the difference in the thickness of the cathode lead-out layer. By thickening the cathode extraction layer, it is possible to prevent oxygen gas and moisture entering from the outside of the capacitor from deteriorating the solid electrolyte layer.

The average thickness of the cathode drawer layer can be obtained, for example, by the following method. First, an image of a cross section of the cathode drawer layer is acquired, an arbitrary five points of the cathode drawer layer are selected, and the thickness of the cathode drawer layer at that portion is measured. The arithmetic mean of the measured five-point thickness can be taken as the average thickness of the cathode lead-out layer.

In the second solid electrolytic capacitor, the average thickness of the cathode extraction layer of the first capacitor element is larger than 1 times the average thickness of the cathode extraction layer of the second capacitor element, and is 1.5 times or more or 2 times. It may be 0.0 times or more. The average thickness of the cathode extraction layer of the first capacitor element may be 5.0 times or less or 3.0 times or less the average thickness of the cathode extraction layer of the second capacitor element. .. These lower and upper limits can be combined arbitrarily. For example, the average thickness of the cathode extraction layer of the first capacitor element may be in the range of 1.5 times to 3.0 times the average thickness of the cathode extraction layer of the second capacitor element.

(Third solid electrolytic capacitor)
In the third solid electrolytic capacitor, the first capacitor element is a resin arranged on the surface and contains a predetermined resin (polymer in another viewpoint) different from the exterior resin, and is a second capacitor element. Is different. The predetermined resin arranged on the surface of the first capacitor element may be referred to as "resin (R)" below. Examples of the resin (R) include a resin having low oxygen permeability and a resin having high heat resistance. The resin (R) arranged on a surface other than the surface of the cathode portion is usually insulating. The resin (R) arranged on the surface of the cathode portion may be usually conductive or may be insulating. The resin having low oxygen permeability may be a thermoplastic resin or a thermosetting resin. Examples of resins with low oxygen permeability include epoxy resins, carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and derivatives thereof. In particular, it is known that the resin having more cross-linking points (resin having a higher cross-linking density) has lower oxygen permeability. For example, a resin using an epoxy resin and a thiol-based curing agent having bifunctionality or higher has low oxygen permeability. Examples of resins with high heat resistance include polyesters, polyimides, polyamides, and derivatives thereof.

The resin (R) is at least a part of the anode part not covered by the cathode part, at least a part of the dielectric layer not covered by the cathode part, and at least a solid electrolyte layer not covered by the cathode extraction layer. It may be arranged so as to cover at least one place selected from the group consisting of a part. The resin (R) may be arranged so as to cover the portion of the first capacitor element that comes into contact with the exterior body (exterior resin) if there is no resin (R). The resin (R) may be present on the surface of the first capacitor element in the form of a resin composition containing another substance (such as an inorganic filler). The resin (R) may be contained in the cathode drawer layer or may be contained in a metal-containing layer (for example, a silver-containing layer).

The third solid electrolytic capacitor may be the first example (E1) described above or the second example (E2). Since the first capacitor element of the second example (E2) is closer to the surface of the exterior body than the other capacitor elements, it is easily affected by oxygen gas and moisture that have entered from the outside of the capacitor. Therefore, by arranging the resin (R) having low oxygen permeability on the surface of the first capacitor element, it is possible to efficiently suppress the deterioration of the characteristics due to the intrusion of oxygen gas and water. The cost can be reduced by arranging the resin (R) only on the surface of the first capacitor element and not arranging the resin (R) on the surface of the second capacitor element.

The resin (R) may be a copolymer containing a vinyl alcohol unit and another unit. For example, the resin (R) may be a copolymer containing ethylene units and vinyl alcohol units, and / or a copolymer containing butenediol units and vinyl alcohol units. The resin (R) may be an ethylene-vinyl alcohol copolymer and / or a butenediol-vinyl alcohol copolymer.

In the fourth solid electrolytic capacitor, the plurality of capacitor elements included in the fourth solid electrolytic capacitor each include a cathode extraction layer, and the cathode extraction layer includes a carbon-containing layer containing carbon. In the fourth solid electrolytic capacitor, the oxygen permeability of the carbon-containing layer of the first capacitor element is lower than the oxygen permeability of the carbon-containing layer of the second capacitor element. According to this configuration, it is possible to suppress a decrease in the characteristics of the capacitor element due to oxygen or the like invading from the outside, and a highly reliable solid electrolytic capacitor can be obtained.

As the carbon in the carbon-containing layer of the first capacitor element, carbon that is less likely to allow oxygen to permeate than the carbon in the carbon-containing layer of the second capacitor element may be used. Alternatively, in the carbon-containing layer of the first capacitor element, the proportion of carbon that does not easily allow oxygen to permeate may be increased in the entire carbon.

Examples of carbon-containing layers having low oxygen permeability include carbon-containing layers containing scaly carbon particles. The scaly carbon particles are likely to be arranged in a layered state. Therefore, oxygen permeability can be reduced by using scaly carbon particles. That is, the scaly carbon particles are an example of carbon that is difficult for oxygen to permeate. The type of carbon constituting the particles is not particularly limited as long as it is in the scaly form, but graphite, graphene and the like are likely to take the scaly form, and the scaly particles are easily available. Examples of other carbon particles contained in the carbon-containing layer include spherical carbon particles.

The average aspect ratio of the scaly carbon particles may be 2 or more, or 3 or more. When the average aspect ratio of the carbon particles is in such a range, a large amount of flat particles such as scaly particles are contained, and it becomes easy to fill the carbon-containing layer in a stacked state. Therefore, the densely formed carbon-containing layer tends to suppress the permeation of air in the carbon-containing layer. When the carbon particles include scaly particles, the average aspect ratio of the carbon particles may be 2000 or less.

The average aspect ratio of the carbon particles can be obtained as follows. First, a scanning electron microscope (SEM) is used to obtain a cross section of the carbon-containing layer or an image of carbon particles. Arbitrary plurality (for example, 10) of carbon particles are selected in the obtained SEM image. Next, for the selected carbon particles, the maximum diameter D1 is measured, and further, the maximum diameter D2 in the direction orthogonal to the maximum diameter D1 is measured. For each carbon particle, the ratio D1 / D2 of D1 to D2 is obtained as the aspect ratio, and the average aspect ratio is obtained by arithmetically averaging these.

The cathode extraction layer of the first capacitor element of the fourth solid electrolytic capacitor may be a layer having an oxygen permeability of 7 cm ³ / m ² · day · atm or less when the thickness is 10 μm. In this case, the cathode extraction layer of the second capacitor element may have an oxygen permeability of more than 7 cm ³ / m ² · day · atm when the thickness is 10 μm.

(Fifth solid electrolytic capacitor)
Each of the plurality of capacitor elements of the fifth solid electrolytic capacitor includes a cathode extraction layer. The cathode extraction layer includes a silver-containing layer containing silver (for example, silver particles) and a resin. The content of the resin in the silver-containing layer of the first capacitor element of the fifth solid electrolytic capacitor is higher than the content of the resin in the silver-containing layer of the second capacitor element. By increasing the content of the resin in the silver-containing layer of the first capacitor element of the fifth solid electrolytic capacitor, the barrier property of the silver-containing layer can be enhanced. That is, in the fifth solid electrolytic capacitor, the barrier property of the first capacitor element, in which the barrier property is important, is higher than the barrier property of the second capacitor element. On the other hand, by lowering the resin content in the silver-containing layer of the second capacitor element and increasing the silver content by that amount, the conductivity of the silver-containing layer can be increased. As a result, the equivalent series resistance (ESR) of the solid electrolytic capacitor can be reduced. If the resin content of the silver-containing layer of all the capacitor elements is reduced in order to reduce the ESR, the difference between the linear expansion coefficient of the exterior resin and the linear expansion coefficient of the silver-containing layer may become large. As a result, high stress is generated between the silver-containing layer of the outermost capacitor element and the exterior resin, and peeling is likely to occur. According to the fifth solid electrolytic capacitor, such peeling can be suppressed.

The resin content CR (1) in the silver-containing layer of the first capacitor element may be 5% by mass or more, or may be in the range of 5% by mass to 25% by mass. The resin contained in the silver-containing layer may be, for example, the resin contained in the silver paste. The resin content CR (2) in the silver-containing layer of the second capacitor element may be less than 10% by mass (for example, less than 5% by mass), and is 0.1% by mass to 10% by mass (for example, 0. It may be in the range of 1% by mass or more and less than 5% by mass). The content rate CR (1) may be in the range of 1.1 to 10 times the content rate CR (2).

An example of a component common to the solid electrolytic capacitor (the above-mentioned solid electrolytic capacitor) of the present embodiment will be described below. However, the above-mentioned description is followed for the configuration peculiar to the above-mentioned solid electrolytic capacitor. As the constituent members of the solid electrolytic capacitor of the present embodiment, known constituent members of the solid electrolytic capacitor may be applied except for the portion characteristic of the present disclosure.

The solid electrolytic capacitor according to this embodiment includes a plurality of capacitor elements. A plurality of capacitor elements are usually connected in parallel. The number of capacitor elements included in the solid electrolytic capacitor may be in the range of 3 to 20 (for example, the range of 4 to 20 or the range of 5 to 20). The capacitor element included in the solid electrolytic capacitor according to the present embodiment includes an anode portion, a cathode portion, and a dielectric layer. The cathode portion includes a solid electrolyte layer and may further include a cathode extraction layer.

The anodes of the plurality of stacked capacitor elements are usually electrically connected to each other. For example, the ends of those anodes may be joined by welding. Then, the anode lead terminal may be bonded to at least one anode portion.

The cathode extraction layers of the laminated capacitor elements are usually electrically connected to each other. A cathode lead terminal may be connected to the cathode lead-out layer of at least one capacitor element. The cathode lead terminal may be connected to the cathode lead-out layer via a conductive adhesive or solder. Alternatively, the cathode lead terminal may be connected to the cathode lead-out layer by welding (resistance welding, laser welding, etc.). The conductive adhesive may be a mixture of a curable resin and conductive particles (carbon particles, metal particles, etc.).

(Anode part)
The anode portion includes an anode body. The anode body is formed using a metal including a valve acting metal. A foil (metal leaf) containing a valve acting metal may be used for the anode body. Examples of valve acting metals include titanium, tantalum, aluminum, and niobium. The anode contains one or more valve acting metals. The anode may contain the valve acting metal in the form of an alloy or an intermetallic compound. The thickness of the anode is not particularly limited. The thickness of the anode body other than the thin portion may be, for example, 15 μm or more and 300 μm or less, and may be 80 μm or more and 250 μm or less.

At least a part of the surface of the anode may be roughened by electrolytic etching or the like. In that case, the anode has a porous portion on its surface. The entire anode may be porous.

(Dielectric layer)
The dielectric layer is formed on at least a portion of the surface of the anode. The dielectric layer may be formed, for example, by anodizing the surface of the anode (for example, anodizing by chemical conversion treatment). In that case, the dielectric layer contains an oxide of the valve acting metal. For example, when aluminum is used as the valve acting metal, the dielectric layer may contain aluminum oxide. The dielectric layer is not limited to this, and may be any one that functions as a dielectric. The dielectric layer may be formed on at least a part of the surface of the porous portion of the anode.
(Solid electrolyte layer)
The solid electrolyte layer is arranged so as to cover at least a part of the dielectric layer. The solid electrolyte layer may be arranged so as to cover the entire surface of the dielectric layer.

The solid electrolyte layer contains, for example, a manganese compound or a conductive polymer. Examples of the conductive polymer include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polythiophene vinylene and the like. These may be used alone or in combination of two or more kinds, or may be a copolymer of two or more kinds of monomers.

In addition, in this specification, polypyrrole, polythiophene, polyfuran, polyaniline and the like mean a polymer having polypyrrole, polythiophene, polyfuran, polyaniline and the like as a basic skeleton, respectively. Therefore, polypyrrole, polythiophene, polyfuran, polyaniline and the like may also contain their respective derivatives. For example, polythiophene includes poly (3,4-ethylenedioxythiophene) and the like.

The conductive polymer may be contained in the solid electrolyte layer together with the dopant. The dopant may be a monomolecular anion or a polymer anion. Specific examples of the monomolecular anion include paratoluenesulfonic acid and naphthalenesulfonic acid. Specific examples of the polymer anion include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly (2-acrylamide-2-methylpropanesulfonic acid), and polyisoprene sulfonic acid. , Polyacrylic acid and the like. These may be used alone or in combination of two or more. Further, these may be polymers of a single monomer or may be a copolymer of two or more kinds of monomers. Of these, a polymer anion derived from polystyrene sulfonic acid is preferable. A preferred example of the solid electrolyte layer is polystyrene sulfonic acid (PSS) -doped poly (3,4-ethylenedioxythiophene) (PEDOT).

The solid electrolyte layer containing the conductive polymer may be formed by a known method. For example, first, the anode body on which the dielectric layer is formed is impregnated with a monomer or an oligomer. Next, a solid electrolyte layer can be formed by polymerizing a monomer or an oligomer by chemical polymerization or electrolytic polymerization. Alternatively, the solid electrolyte layer may be formed by contacting the anode body on which the dielectric layer is formed with a solution or dispersion of the conductive polymer and then drying the anode body.
(Cathode drawer layer)
The cathode extraction layer may be formed so as to cover at least a part of the solid electrolyte layer, or may be formed so as to cover the entire surface of the solid electrolyte layer.

The configuration of the cathode extraction layer is not limited, and any conductive layer that enables good electrical connection between the solid electrolyte layer and other members (cathode lead terminal or the cathode portion of another capacitor element) may be used. The cathode extraction layer may include a carbon-containing layer formed on the solid electrolyte layer and a metal-containing layer (for example, a silver-containing layer) formed on the carbon-containing layer.

(Carbon-containing layer)
The carbon-containing layer contains a carbon material and has conductivity. The carbon material is not particularly limited. Examples of the carbon material include graphite, carbon black, graphene pieces, and carbon nanotubes.

The carbon-containing layer may contain a binder resin and / or an additive, if necessary. The binder resin is not particularly limited, and examples thereof include known binder resins used for manufacturing general capacitor elements. Examples of the binder resin include the above-mentioned thermoplastic resin or curable resin. Additives include, for example, dispersants, surfactants, antioxidants, preservatives, bases, and / or acids.

(Metal-containing layer)
The metal-containing layer contains a metal material. The metal material is not particularly limited. From the viewpoint of conductivity, the metallic material may contain silver. That is, the metal-containing layer may be a silver-containing layer. The metal-containing layer may be formed, for example, by using a metal paste (for example, silver paste) containing metal particles (for example, silver particles).

The shape of the metal material is not particularly limited. The metallic material may contain spherical and / or scaly metal particles. The average aspect ratio of spherical metal particles (hereinafter referred to as spherical particles) is, for example, less than 1.5. The average aspect ratio of the scaly metal material is, for example, 1.5 or more and 2 or more.

The ratio of the metal material in the metal-containing layer is not particularly limited. The above ratio may be 60% by volume or more, 70% by volume or more, or 80% by volume or more in that the resistance tends to be small.

The metal-containing layer may further contain a binder resin. The proportion of the binder resin in the metal-containing layer is not particularly limited. From the viewpoint of electrical resistance, the proportion of the binder resin in the metal-containing layer may be 60% by volume or less, 20% by volume or less, 10% by volume or less, or 0% by volume. The above ratio may be 0.1% by volume or more. The volume ratio of each component in the metal-containing layer can be analyzed by, for example, energy dispersive X-ray spectroscopy (SEM-EDX).

The thickness of the metal-containing layer is not particularly limited. The thickness of the metal-containing layer may be 0.1 μm or more and 50 μm or less, and may be 1 μm or more and 20 μm or less. The thickness of the metal-containing layer is an average value of any five points in the cross section of the metal-containing layer in the thickness direction.

The cathode extraction layer may be formed by a known method. For example, the material of the cathode drawer layer may be applied and, if necessary, dried and / or heat treated.

(Exterior body)
The exterior body contains exterior resin. Examples of exterior resins include curable resins and engineering plastics. Examples of the curable resin (for example, a thermosetting resin) include epoxy resin, phenol resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane, and unsaturated polyester. Engineering plastics include general purpose engineering plastics and super engineering plastics. Examples of engineering plastics include polyimide and polyamide-imide.

The exterior body may contain other additives such as an inorganic filler in addition to the exterior resin. That is, at least a part of the exterior body may be composed of the resin composition. Examples of the inorganic filler include silica (molten silica and the like), talc, calcium carbonate, aluminum oxide and the like.

(Lead terminal)
The material of the lead terminal (anode lead terminal and cathode lead terminal) is not particularly limited as long as it is electrochemically and chemically stable and has conductivity. The material of the lead terminal is preferably a metal (for example, copper, copper alloy, etc.). The thickness of the lead terminal may be in the range of 25 μm to 200 μm (for example, in the range of 25 μm to 100 μm).

(Example of manufacturing method of solid electrolytic capacitor)
The method for manufacturing the solid electrolytic capacitor according to the present embodiment is not particularly limited. A known manufacturing method may be applied to these manufacturing methods, or a part of the known manufacturing method may be modified and applied according to the configuration of the solid electrolytic capacitor of the present embodiment. A capacitor element having a unique configuration may be manufactured according to the configuration. For example, when the capacitor element contains a component having a unique composition, the component may be formed so as to have the composition. For example, the materials may be mixed to form the constituent member so as to have the composition. Further, when the capacitor element includes a layer having a predetermined thickness, the layer may be formed so as to have such a thickness. For example, the thickness of the layer may be changed by changing the thickness of the material for forming the layer.

In the manufacturing method of one example, first, a capacitor element including an anode (anode portion), a dielectric layer, and a cathode portion is manufactured by the above-mentioned method. Next, the anode lead terminal and the cathode lead terminal are connected to the capacitor element. Next, they are sealed with an exterior body. In this way, a solid electrolytic capacitor is manufactured.

Examples of the embodiments according to the present disclosure will be specifically described below with reference to the drawings. The above-mentioned components can be applied to the components of the examples described below. Moreover, the example described below can be changed based on the above description. Further, the matters described below may be applied to the above-described embodiment. Further, in the embodiments described below, components that are not essential for the solid electrolytic capacitor of the present disclosure may be omitted. The solid electrolytic capacitor described below may be manufactured by the method described above. In the following figures, some members may be omitted for ease of understanding.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing the solid electrolytic capacitor 10 according to the first embodiment. The solid electrolytic capacitor 10 encloses a plurality of capacitor elements 100a to 100d, an anode lead terminal 21 and a cathode lead terminal 31 electrically connected to the plurality of capacitor elements 100a to 100d, and a plurality of capacitor elements 100a to 100d. Includes the exterior body 40 to be used.

The capacitor elements 100a, 100b, 100c, and 100d are laminated in the direction Ds connecting the lower surface 40b and the upper surface 40t of the exterior body 40. In the following, the name "capacitor element 100" may be used as a general-purpose name for the capacitor elements 100a to 100d. Each of the plurality of capacitor elements 100 includes an anode body 110 and a cathode portion 130. Note that FIG. 1 omits the illustration of the dielectric layer.

The exterior body 40 has a lower surface 40b and an upper surface 40t on the opposite side of the lower surface 40b. The lower surface 40b is a surface on which the anode terminal portion 21a and the cathode terminal portion 31a are exposed. Further, the exterior body 40 has a front surface 40f and a rear surface 40r shown in FIG. The front surface 40f and the rear surface 40r are side surfaces connecting the lower surface 40b and the upper surface 40t, respectively. An anode lead terminal 21 is connected to one end of the anode body 110. The front surface 40f is a surface existing in the direction in which one end of the anode body 110 extends. The rear surface 40r is a surface opposite to the front surface 40f.

The anode lead terminal 21 includes an anode terminal portion 21a exposed on the lower surface 40b of the exterior body 40 and a connection portion 21b connected to the anode lead terminal 21. The cathode lead terminal 31 includes a cathode terminal portion 31a exposed on the lower surface 40b of the exterior body 40 and a connecting portion 31b connected to the cathode portion 130 (for example, the cathode extraction layer) of the capacitor element 100. As shown in FIG. 1, the connecting portion 31b may be connected to the cathode portion 130 via the conductive adhesive layer 41. Alternatively, the connecting portion 31b may be directly connected to the cathode portion 130.

In the example shown in FIG. 1, the cathode lead terminal 31 is connected to the capacitor element 100a closest to the lower surface 40b. The cathode lead terminal 31 may be connected to the capacitor element 100a closest to the upper surface 40t. Alternatively, as shown in FIG. 4, the cathode lead terminal 31 may be connected to a capacitor element 100 other than the capacitor elements 100a and 100d.

In the case of the example shown in FIG. 1, the capacitor element having the largest area of the portion connected to the cathode lead terminal 31 without going through another capacitor element 100 is the capacitor element 100a. As shown in FIG. 1, when the capacitor element 100 (specifically, the cathode portion 130) is connected to the cathode lead terminal 31 by the conductive adhesive layer 41, “without interposing another capacitor element 100”. The "area of the portion connected to the cathode lead terminal 31" is the area SA between the capacitor element 100 and the conductive adhesive layer in the region SA where the conductive adhesive layer 41 is in contact with both the capacitor element 100 and the cathode lead terminal 31. It means the contact area with 41.

In the case of the example shown in FIG. 1, the capacitor element 100 closest to the lower surface 40b is the capacitor element 100a, and the capacitor element 100 closest to the upper surface 40t is the capacitor element 100d. In this example, the capacitor element 100 having the largest area of the portion connected to the cathode lead terminal 31 without going through another capacitor element 100 and the capacitor element 100 closest to the lower surface 40b are both capacitor elements 100a. ..

A cross-sectional view of an example of the capacitor element 100 is schematically shown in FIG. The capacitor element 100 includes an anode body (anode portion) 110, a dielectric layer 120 covering at least a part of the anode body 110, and a cathode part 130 covering at least a part of the dielectric layer 120. The cathode portion 130 includes a solid electrolyte layer 131 that covers at least a part of the dielectric layer 120, and a cathode extraction layer 132 formed on the solid electrolyte layer 131. The cathode extraction layer 132 includes a carbon-containing layer 132a and a silver-containing layer 132b laminated in order from the solid electrolyte layer 131 side. The capacitor element 100 may include the separating member 141 shown in FIG.

A cross-sectional view of another example of the capacitor element 100 is shown in FIG. The capacitor element 100 of FIG. 3 differs from the capacitor element 100 of FIG. 2 in that it includes an insulating separating member 141 and an insulating resin layer 142. The resin layer 142 contains or is made of the resin (R) described above. The separating member 141 is arranged in a region on the anode body 110 (or on the dielectric layer 120) where the cathode portion 130 is not formed. The separating member 141 is arranged in a region of the region close to the cathode portion 130. The separating member 141 can suppress a short circuit between the anode body 110 and the cathode portion 130. The resin layer 142 is arranged so as to cover at least a part of the dielectric layer 120 that is not covered by the cathode portion 130. The resin layer 142 can suppress the invasion of oxygen and moisture from places where they are likely to invade. The resin layer 142 may be arranged so as to cover the entire surface of the capacitor element 100, except for a portion connected to the lead terminal or another capacitor element 100, or substantially the entire surface.

In an example solid electrolytic capacitor, only the first capacitor element contains the resin layer 142, and the second capacitor element does not include the resin layer 142. According to this configuration, it is possible to suppress an increase in manufacturing cost and improve the characteristics of a solid electrolytic capacitor at the same time.

(Embodiment 2)
FIG. 4 is a cross-sectional view schematically showing the solid electrolytic capacitor according to the second embodiment. The solid electrolytic capacitor 10a of FIG. 4 is different from the solid electrolytic capacitor 10 shown in FIG. 1 in that the arrangement of the capacitor element 100 and the connection method of the lead terminals are different. As the capacitor element 100, the capacitor element described in the first embodiment can be used.

The capacitor elements 100a, 100b, 100c, and 100d are laminated in the direction Ds connecting the lower surface 40b and the upper surface 40t of the exterior body 40. FIG. 4 shows an example in which the connecting portion 31b is directly connected to the cathode portion 130, but as shown in FIG. 1, even if the connecting portion 31b is connected to the cathode portion 130 by the conductive adhesive layer. good.

In the case of the example shown in FIG. 4, the capacitor element 100 closest to the lower surface 40b is the capacitor element 100a, and the capacitor element 100 closest to the upper surface 40t is the capacitor element 100d. The capacitor elements 100 having the largest area of the portion connected to the cathode lead terminal 31 without passing through another capacitor element 100 are the capacitor elements 100b and 100c.

As shown in FIG. 4, when the capacitor element 100 (specifically, the cathode portion 130) is directly connected to the cathode lead terminal 31, "connect to the cathode lead terminal 31 without going through another capacitor element 100". The "area of the portion" means the contact area between the capacitor element 100 and the cathode lead terminal 31.

In the solid electrolytic capacitors 10 and 10a of the first and second embodiments, they are connected to the cathode lead terminal 31 without the intervention of the capacitor element 100 closest to the lower surface 40b, the capacitor element 100 closest to the upper surface 40t, and another capacitor element 100. At least one capacitor element selected from the group consisting of the capacitor element 100 having the largest area of the portion is selected as the first capacitor element. The capacitor element 100 other than the first capacitor element is the second capacitor element. In the solid electrolytic capacitors 10 and 10a, the configuration of the first capacitor element is different from the configuration of the second capacitor element. For example, in the case of the first solid electrolytic capacitor described above, the thickness of the first capacitor element is thicker than the thickness of the second solid electrolytic capacitor. Similarly, in other solid electrolytic capacitors, the configuration of the first capacitor element is different from the configuration of the second capacitor element.

The present disclosure can be used for solid electrolytic capacitors.

10, 10a: Solid electrolytic capacitor 21: Anode lead terminal 21a: Anode terminal 31: Cathode lead terminal 31a: Cathode terminal 40: Exterior body 40b: Bottom surface 40t: Top surface 100, 100a to 100d: Capacitor element 132: Cathode lead-out layer 132a: Carbon-containing layer 132b: Silver-containing layer Ds: Direction

Claims (8)

With multiple capacitor elements
An anode lead terminal and a cathode lead terminal electrically connected to the plurality of capacitor elements,
An exterior body that encloses the plurality of capacitor elements and contains an exterior resin, and a solid electrolytic capacitor that includes the exterior body.
The anode lead terminal and the cathode lead terminal include an anode terminal portion and a cathode terminal portion exposed on the lower surface of the exterior body, respectively.
The exterior body has an upper surface opposite to the lower surface, and has an upper surface opposite to the lower surface.
The plurality of capacitor elements are laminated in a direction connecting the lower surface and the upper surface.
A group consisting of the capacitor element closest to the lower surface, the capacitor element closest to the upper surface, and the capacitor element having the largest area of a portion connected to the cathode lead terminal without passing through another capacitor element. The configuration of at least one first capacitor element selected from the above is a solid electrolytic capacitor different from the configuration of the second capacitor element which is the capacitor element other than the first capacitor element. The solid electrolytic capacitor according to claim 1, wherein the first capacitor element is the capacitor element having the largest area. The solid electrolytic capacitor according to claim 1, wherein the first capacitor element is the capacitor element closest to the lower surface and / or the capacitor element closest to the upper surface. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein the thickness of the first capacitor element is thicker than the thickness of the second capacitor element. Each of the plurality of capacitor elements includes a cathode lead-out layer.
The solid electrolysis according to any one of claims 1 to 3, wherein the average thickness of the cathode extraction layer of the first capacitor element is thicker than the average thickness of the cathode extraction layer of the second capacitor element. Capacitor. One of claims 1 to 3, wherein the first capacitor element is different from the second capacitor element in that it contains a predetermined resin which is a resin arranged on the surface and is different from the exterior resin. The solid electrolytic capacitor described in the section. Each of the plurality of capacitor elements includes a cathode lead-out layer.
The cathode extraction layer includes a carbon-containing layer containing carbon, and the cathode drawer layer includes a carbon-containing layer.
The solid according to any one of claims 1 to 3, wherein the oxygen permeability of the carbon-containing layer of the first capacitor element is lower than the oxygen permeability of the carbon-containing layer of the second capacitor element. Electrolytic capacitor. Each of the plurality of capacitor elements includes a cathode lead-out layer.
The cathode drawer layer includes a silver-containing layer containing silver and a resin, and contains a silver-containing layer.
One of claims 1 to 3, wherein the content of the resin in the silver-containing layer of the first capacitor element is higher than the content of the resin in the silver-containing layer of the second capacitor element. The solid electrolytic capacitor described in.

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