Solid electrolytic capacitor

Abstract

This solid electrolytic capacitor comprises: a capacitor element that is provided with an anode part and a cathode part; an exterior body that seals the capacitor element; a first external electrode that is electrically connected to the anode part; and a second external electrode that is electrically connected to the cathode part. An outer surface of the exterior body has a first surface, a second surface that is opposite from the first surface, and a third surface that is formed in a direction intersecting the first surface and the second surface. At least one of anode part and cathode part end surfaces is exposed from the exterior body at the third surface and is electrically connected to the first external electrode or the second external electrode. The angle θ1 formed by the third surface and the first surface is acute.

Description

Solid electrolytic capacitors Cross-reference of related applications

[0001] This disclosure claims priority rights to Japanese Patent Application No. 2025-013224, filed with the Japan Patent Office on 29 January 2025, and the entirety of the said patent application is incorporated herein by reference.

[0002] This invention relates to a solid electrolytic capacitor.

[0003] A solid electrolytic capacitor includes, for example, a capacitor element having an anode portion and a cathode portion, an outer casing that encloses the capacitor element, a first external electrode electrically connected to the anode portion, and a second external electrode electrically connected to the cathode portion.

[0004] Regarding the method of electrical connection between a capacitor element and an external electrode, a method has been proposed in which the anode or cathode of the capacitor is exposed on one side of the outer casing, and the connection with the external electrode is made at the exposed end face, from the viewpoint of reducing ESR and increasing capacitance. An internal electrode is formed on the exposed end face by a method such as thermal spraying, and the electrical connection with the external electrode is made via the internal electrode.

[0005] For example, Patent Document 1 proposes an electrolytic capacitor comprising: a laminate having a capacitor element including an anode having a dielectric layer on its surface and a cathode facing the anode; a sealing resin sealing the periphery of the laminate; a first external electrode provided on a first end face of the resin molded body and electrically connected to the anode exposed from the first end face; and a second external electrode provided on a second end face of the resin molded body and electrically connected to the cathode exposed from the second end face, wherein the first external electrode comprises, in order from the first end face side of the resin molded body, a first thermal spray electrode layer and a second thermal spray electrode layer in contact with the first thermal spray electrode layer and having a higher porosity than the first thermal spray electrode layer.

[0006] International Publication No. 2021 / 140894

[0007] As described in Patent Document 1, when forming internal electrodes on the end face of a resin molded body using a film deposition technique that involves the physical collision of conductive particles, such as thermal spraying, AD (Aerosol Deposition), or CS (Cold Spray), the internal electrodes are formed thicker near the central axis of the thermal spray nozzle and thinner further away from the central axis, resulting in variations in the thickness of the internal electrodes. As a result, variations in the characteristics of the electrolytic capacitor (for example, an increase in ESR) due to variations in the thickness of the internal electrodes are more likely to occur.

[0008] One aspect of the present invention relates to a solid electrolytic capacitor comprising a capacitor element having an anode portion and a cathode portion, an outer casing that encloses the capacitor element, a first external electrode electrically connected to the anode portion, and a second external electrode electrically connected to the cathode portion, wherein the outer surface of the outer casing has a first surface, a second surface facing the first surface, and a third surface formed in a direction intersecting the first and second surfaces, at least one of the end faces of the anode portion and the cathode portion is exposed from the outer casing on the third surface and is electrically connected to the first external electrode or the second external electrode, and the angle θ1 between the third surface and the first surface is acute.

[0009] According to this disclosure, it is possible to provide a solid electrolytic capacitor in which variations in the thickness of the internal electrodes are suppressed. Novel features of the present invention are described in the appended claims, but the present invention, in conjunction with other objects and features of the present invention, will be better understood by the following detailed description in conjunction with the drawings, both in terms of structure and content.

[0010] This is a schematic cross-sectional view illustrating the process of forming an internal electrode (contact layer) on the end face of the anode portion exposed on the third surface of the outer casing for a conventional solid electrolytic capacitor, and the problems that arise in this process. This is a schematic cross-sectional view illustrating the process of forming an internal electrode (contact layer) on the end face of the anode portion exposed on the third surface of the outer casing for a solid electrolytic capacitor according to one embodiment of the present disclosure. This is a side cross-sectional view showing the configuration of a capacitor element according to one embodiment of the present disclosure. This is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to one embodiment of the present disclosure. This is a perspective view of a solid electrolytic capacitor as seen from the anode side in Figure 3 when the first external electrode is not attached. This is a perspective view of a solid electrolytic capacitor as seen from the cathode side in Figure 3 when the second external electrode is not attached. This is another example of a perspective view of a solid electrolytic capacitor as seen from the cathode side in Figure 3 when the second external electrode is not attached.

[0011] The embodiments of this disclosure will be described below with examples, but this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values, materials, etc. may be applied as long as the effects of this disclosure are obtained. Notwithstanding, known components may be applied to components of parts that are characteristic of this disclosure. In this specification, when "the range of numerical values ​​A to numerical values ​​B" is used, that range includes numerical values ​​A and B.

[0012] In the following explanation, when examples are given of lower and upper limits for specific physical properties or conditions, any combination of either of the given lower limits and any of the given upper limits is permitted, as long as the lower limit does not exceed the upper limit. When multiple materials are given as examples, unless otherwise specified, one type may be selected and used alone, or two or more types may be used in combination.

[0013] This disclosure includes any combination of two or more claims that can be arbitrarily selected from the claims set forth in the attached claims. In other words, any combination of two or more claims that can be arbitrarily selected from the claims set forth in the attached claims is possible, as long as it does not result in a technical inconsistency.

[0014] A solid electrolytic capacitor according to the embodiment of this disclosure comprises a capacitor element having an anode portion and a cathode portion, an outer casing that encloses the capacitor element, a first external electrode electrically connected to the anode portion, and a second external electrode electrically connected to the cathode portion.

[0015] The outer surface of the exterior body has a first surface, a second surface opposite the first surface, and a third surface formed in a direction intersecting the first and second surfaces. The third surface connects, for example, the first surface and the second surface.

[0016] The first and second surfaces correspond to the top and bottom surfaces of the solid electrolytic capacitor. The first surface corresponds to the bottom surface of the solid electrolytic capacitor, and the bottom surface may also be the mounting surface for the solid electrolytic capacitor on the circuit board. The top surface may also be the mounting surface for the solid electrolytic capacitor on the circuit board. Typically, the first and second surfaces of the solid electrolytic capacitor are approximately parallel. In the following, the direction from the first surface to the second surface may be referred to as the height direction of the solid electrolytic capacitor.

[0017] Typically, solid electrolytic capacitors have a roughly rectangular parallelepiped shape. In this case, the outer surface of the casing may have four main surfaces corresponding to the sides of the solid electrolytic capacitor, in addition to the first and second surfaces. One of the four main surfaces is the third surface. The outer surface of the casing may have a fourth surface that is formed in a direction intersecting the first and second surfaces, corresponding to the sides of the solid electrolytic capacitor, and that faces the third surface. The fourth surface connects, for example, the first and second surfaces at a different location from the third surface.

[0018] At least one of the end faces of the anode and cathode portions is exposed from the casing on the third surface and is electrically connected to one of the first external electrode and the second external electrode. In other words, at least one of the end faces of the anode and cathode portions is electrically connected to the external electrode on the third surface of the side of the solid electrolytic capacitor. Both end faces of the anode and cathode portions may be electrically connected to the external electrode on the side of the solid electrolytic capacitor. The other end face of the anode and cathode portions is exposed from the casing on the fourth surface and may be electrically connected to the other of the first external electrode and the second external electrode.

[0019] The angle θ1 between the third surface and the first surface is acute, and the third surface is inclined obliquely with respect to the first surface. As a result, as will be described later, when the end faces of the anode and / or cathode exposed on the third surface are electrically connected to an external electrode, variations in the thickness of the internal electrode layer (hereinafter also referred to as the "contact layer") covering the end faces can be reduced. Furthermore, wear on the outer casing is suppressed, thereby suppressing the deterioration of the characteristics and reliability of the solid electrolytic capacitor.

[0020] In this embodiment of the solid electrolytic capacitor, a plurality of capacitor elements may be provided. The solid electrolytic capacitor of this embodiment may have an element stack in which a plurality of capacitor elements are stacked. The element stack can be constructed, for example, by stacking a plurality of capacitor elements in the height direction. The outer casing encloses the element stack.

[0021] It is preferable that the capacitor elements or the element stack are positioned within the outer casing so that they are biased towards the first surface rather than the second surface. That is, the distance L between the element stack and the first surface. １ However, the distance L between the second surface of the element stack is ２ It is preferable that it be shorter than this. When a solid electrolytic capacitor is constructed using individual capacitor elements, the distance L to the first surface of the capacitor element is the distance L to the first surface of the capacitor element. １ However, the distance L between the second surface of the capacitor element and the first surface is... ２ A shorter distance L is preferable. In this case, the effect of reduced sealing performance due to wear on the outer casing is suppressed, and a solid electrolytic capacitor with even greater reliability can be realized. ２ is, distance L １ Larger than L １ It may be 1.1 times or more, L １ It is preferable to have 1.5 times or more of this.

[0022] The angle θ1 between the third surface and the first surface of the outer casing is less than 90°, and may be, for example, 85° or greater. Similarly, the angle θ2 between the fourth surface and the first surface of the outer casing is less than 90°, and may be, for example, 85° or greater. When θ1 and / or θ2 are within this range, variations in the thickness of the contact layer are reduced, wear of the outer casing is suppressed, and the effect of suppressing the deterioration of the characteristics and reliability of the solid electrolytic capacitor is easily achieved.

[0023] The width Wb of the first face in the first direction from the third face to the fourth face may be longer than the width Wt of the second face in the first direction, and may be 1.05 times or less of Wt (1 < Wb / Wt ≤ 1.05). The width Wb of the first face may be 1.01 times or more and 1.05 times or less of the width Wt of the second face (1.01 < Wb / Wt ≤ 1.05).

[0024] The solid electrolytic capacitor may have a trapezoidal shape in the outline of its casing on the sides perpendicular to the first and third surfaces. In this case, the width Wt is the length of the upper base of the trapezoid, and the width Wb is the length of the lower base of the trapezoid.

[0025] The solid electrolytic capacitor of this embodiment may have a contact layer covering at least one of the end faces of the anode and cathode portions on the third surface. This allows at least one of the anode and cathode portions to be electrically connected to a first external electrode or a second external electrode via the contact layer. The contact layer may be formed by a film deposition technique that causes conductive particles to physically collide with the third surface at high speed.

[0026] The configuration of a capacitor element and a solid electrolytic capacitor according to one embodiment of this disclosure will be described below with reference to the drawings. In the following description, the case in which the bottom surface is the mounting surface for the solid electrolytic capacitor on the circuit board will be explained.

[0027] Figures 1A and 1B are cross-sectional views illustrating one step in the manufacturing of a solid electrolytic capacitor, specifically the process of electrically connecting the end face of at least one of the anode portion (anode body 11) and cathode portion 14 (in this case, the anode portion) exposed on the third surface of the outer casing to an external electrode. In particular, these are cross-sectional views illustrating the process of forming a contact layer 30 on the end face of the anode portion.

[0028] In Figures 1A and 1B, the outer surface of the casing 120 has a first surface S1 corresponding to the bottom surface (mounting surface to the circuit board) of the solid electrolytic capacitor, a second surface S2 corresponding to the top surface of the solid electrolytic capacitor, and a third surface S3 and a fourth surface S4 connecting the first surface S1 and the second surface S2, corresponding to the side surfaces of the solid electrolytic capacitor. On the third surface S3, the end faces of the anode portions of each capacitor element 10 in the element stack are exposed.

[0029] The process of forming a contact layer on the exposed end face of the anode portion can be carried out, for example, by physically impacting conductive particles onto the third surface S3 at high speed using methods such as thermal spraying, AD method, or CS method. By spraying a gas containing fine particles of conductive particles (e.g., metal particles) from a thermal spray nozzle 200 onto the third surface S3, the metal particles adhere to the end face and spread across the entire end face due to their malleability, thereby forming a contact layer 30.

[0030] Figure 1A shows an example corresponding to the prior art, where the first surface S1 and the third surface S3 are approximately perpendicular. The gas containing metal particles injected from the thermal spray nozzle 200 spreads in a direction perpendicular to the central axis of the nozzle and reaches the third surface S3. As a result, the thickness of the contact layer 30 formed varies depending on the distance from the nozzle. The contact layer may be formed thicker near the central axis of the nozzle and thinner as it moves away from the central axis.

[0031] In contrast, Figure 1B shows an example corresponding to this embodiment, where the angle θ1 between the third surface S3 and the first surface S1 is acute. In this case, the height of the thermal spray nozzle 200 is higher than the height of the center of the element stack, and the thermal spray nozzle 200 is positioned off-center towards the second surface S2, and the solid electrolytic capacitor is positioned relative to the thermal spray nozzle 200. It is preferable to position the height of the thermal spray nozzle to match the height of the anode portion of the capacitor element located closest to the second surface S2 in the element stack.

[0032] In FIG. 1B, the end face X of the anode portion of the capacitor element located on the first surface S1 side in the element laminate is away from the central axis of the nozzle 200. However, since the third surface S3 is inclined with an acute angle θ1, the distance from the end face X to the nozzle becomes shorter than the case where θ1 is a right angle. As a result, the film formation rate is improved. Consequently, the contact layer 30 can be formed with a film thickness comparable to that of the contact layer 30 formed on the end face Y of the anode portion of the capacitor element located at substantially the same height as the central axis of the nozzle. Thereby, the variation in the thickness of the contact layer formed on the end face of the anode portion of the capacitor element within the element laminate can be reduced.

[0033] On the other hand, in the region A of the third surface S3 on the second surface S2 side rather than the element laminate, shaving of the exterior body 120 may occur. However, since the third surface S3 is inclined with an acute angle θ1 with the first surface S1 (and an obtuse angle with the second surface S2), the distance from the thermal spraying nozzle to the region A becomes longer. As a result, the amount of shaving of the exterior body is reduced.

[0034] In addition, the element laminate is disposed biased toward the first surface S1 side rather than the second surface S2, and the distance L ２ to the second surface S2 of the element laminate １ is made longer than the distance L to the first surface S1 of the element laminate, so that a sufficient thickness of the exterior body 120 can be ensured between the second surface S2 and the element laminate, and the reliability can be further enhanced while suppressing a decrease in reliability due to shaving of the exterior body.

[0035] FIG. 2 is a side cross-sectional view showing the configuration of a capacitor element according to an embodiment of the present disclosure.

[0036] (Capacitor Element) As shown in FIG. 2, the capacitor element 10 includes an anode body 11 extending in the first direction D1, a dielectric layer (not shown) covering at least a part of the anode body 11, a solid electrolyte layer 12 covering at least a part of the dielectric layer, and a cathode lead-out layer 13 covering at least a part of the solid electrolyte layer 12. In the capacitor element 10 shown in FIG. 2, the anode body 11 is the anode portion, and the cathode portion 14 is formed by the solid electrolyte layer 12 and the cathode lead-out layer 13. The first direction D1 is a direction parallel to the main surface of the anode body 11 and is also the length direction of the anode body 11.

[0037] In the capacitor element 10, the anode body 11 has a first anode body portion 11a that does not have the solid electrolyte layer 12 disposed on one side in the first direction D1, and a second anode body portion 11b that has the solid electrolyte layer 12 disposed on the other side in the first direction D1. The first anode body portion 11a functions as an anode lead-out portion. In FIG. 2, for convenience, the boundary between the first anode body portion 11a and the second anode body portion 11b is shown by a solid line.

[0038] In the capacitor element 10, both the first anode body portion 11a and the second anode body portion 11b have a roughened portion 11c that extends from at least one outer surface toward the central portion in the thickness direction, and a core portion 11d that is continuous with the roughened portion 11c in the thickness direction. In the first anode body portion 11a and the second anode body portion 11b shown in FIG. 2, the roughened portion 11c is formed so as to extend from each of the two outer surfaces toward the central portion in the thickness direction. That is, in the first anode body portion 11a and the second anode body portion 11b, the core portion 11d is sandwiched between a pair of roughened portions 11c in the thickness direction. The outer surfaces of the first anode body portion 11a and the second anode body portion 11b respectively mean the main surfaces of the first anode body portion 11a and the second anode body portion 11b.

[0039] In the capacitor element 10, the roughened portion 11c of the first anode body portion 11a may have a thin portion 11c1 that is thinner than the roughened portion 11c of the second anode body portion 11b. The thin portion 11c1 usually has a lower porosity than the roughened portion 11c of the second anode body portion 11b. The roughened portion 11c can be obtained by compressing the entire roughened portion 11c of the first anode body portion 11a in the thickness direction, or by compressing a part of the roughened portion 11c of the first anode body portion 11a in the thickness direction to form the thin portion 11c1, and then removing the uncompressed portion by cutting. Note that the removal of the uncompressed portion may be performed after forming the capacitor element 10 with the roughened portion 11c of the first anode body portion 11a having the uncompressed portion and sealing the capacitor element 10 with a sealing resin.

[0040] The separation member 15 is disposed in the thin portion 11c1. The contact between the first anode body portion 11a and the cathode portion 14 is restricted by the separation member 15. Thereby, it is possible to suppress the occurrence of a short circuit between the first anode body portion 11a and the cathode portion 14. The separation member 15 may be disposed on both surfaces of the thin portion 11c1 in the capacitor element 10, or may be disposed on only one surface.

[0041] (Anode body) The anode body 11 is formed using a metal containing a valve-acting metal. For the anode body 11, for example, a foil (metal foil) containing a valve-acting metal can be used. Examples of the valve-acting metal include aluminum, tantalum, niobium, and titanium. The anode body 11 contains one or more valve-acting metals. The anode body 11 may contain the valve-acting metal in the form of an alloy or an intermetallic compound. The thickness of the anode body 11 is not particularly limited. The thickness of the anode body 11 other than the thin portion 11c1, in other words, the thickness of the uncompressed portion of the anode body 11 is, for example, 15 μm or more and 300 μm or less, and may be 80 μm or more and 250 μm or less.

[0042] As described above, the anode body 11 has a first anode body portion 11a and a second anode body portion 11b, and both the first anode body portion 11a and the second anode body portion 11b have a core portion 11d that is continuous with the roughened portion 11c in the thickness direction. In the anode body 11, the roughened portion 11c may be formed by an etching process such as electrolytic etching. That is, the roughened portion 11c may be an etched layer. The roughened portion 11c is a region having a plurality of fine pores. On the other hand, the core portion 11d is, for example, a region that has not been electrolytically etched.

[0043] (Separation Member) The separation member 15 preferably has high insulating properties. The separation member 15 may be a conventionally known insulating tape (resist tape). For example, polyimide tape (PI tape) can be used as such an insulating tape. The insulating tape has an adhesive layer. Therefore, if the separation member 15 is an insulating tape, the insulating region of the solid electrolytic capacitor described later may be formed by the end face of the insulating tape.

[0044] The separation member 15 may be formed by adhering a resin composition containing a curable resin to at least a portion of the surface of the thin-walled portion 11c1. In other words, the separation member 15 may be a resin layer containing a curable resin. If the separation member 15 is a resin layer, the resin layer may have an adhesive layer on the end face on the first anode portion 11a side in the first direction D1. In this case, the insulating region of the solid electrolytic capacitor, which will be described later, can be formed by the end face of the resin layer on the first anode portion 11a side in the first direction D1. The adhesive layer can be formed by various known adhesives. Examples of adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, and urethane adhesives.

[0045] The curable resin may be a thermosetting resin or a photocurable resin. The photocurable resin may be a resin that cures with visible light or ultraviolet light. Examples of curable resins include epoxy resins, polyimide resins, silicon resins, phenolic resins, urea resins, melamine resins, unsaturated polyester resins, furan resins, polyurethane resins, curable acrylic resins, and photoresist resins. The resin composition may optionally contain a curing agent, a curing accelerator, a flame retardant, a filler, a coupling agent, a colorant, a mold release agent, and an inorganic ion scavenger. Various known agents can be used. In addition to the curable resin, the resin composition may also contain a thermoplastic resin (for example, a polyamide resin, a polyamide-imide resin, a polyolefin resin, and a polyester resin).

[0046] (Dielectric layer) As described above, the dielectric layer covers at least a portion of the anode 11. The dielectric layer may be formed, for example, by anodizing the surface of the anode 11 with a chemical conversion treatment. Therefore, the dielectric layer may contain an oxide of the valve metal. For example, if aluminum is used as the valve metal, the dielectric layer may contain Al ２ O ３ This may include the dielectric layer. However, the dielectric layer is not limited to this and can be any material that functions as a dielectric. Preferably, the dielectric layer is formed on at least a portion of the surface of the roughened portion 11c of the first anode body portion 11a and the roughened portion 11c of the second anode body portion 11b. Preferably, the dielectric layer is formed on the outer surface of the roughened portion 11c of the first anode body portion 11a and the second anode body portion 11b, and more preferably, in addition to being formed on the outer surface of the roughened portion 11c, it is formed along the inner wall surface of the plurality of fine pores in the roughened portion 11c.

[0047] (Solid Electrolyte Layer) As described above, the solid electrolyte layer 12 covers at least a portion of the dielectric layer. The solid electrolyte layer 12 is also located in the second anode portion 11b. That is, the solid electrolyte layer 12 covers at least a portion of the dielectric layer in the second anode portion 11b. The solid electrolyte layer 12 may cover the entire surface of the dielectric layer in the second anode portion 11b.

[0048] The solid electrolyte layer 12 preferably contains a conductive polymer. Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylvinylene, polyacene, and polythiophenevinylene. These may be used individually or in combination of two or more. The conductive polymer may also be a copolymer of two or more monomers.

[0049] In this specification, polypyrrole, polythiophene, polyfuran, and polyaniline, etc., refer to polymers that have polypyrrole, polythiophene, polyfuran, and polyaniline, etc., as their basic skeletons. Therefore, polypyrrole, polythiophene, polyfuran, and polyaniline, etc., may also include their respective derivatives. For example, polythiophene includes poly(3,4-ethylenedioxythiophene), etc.

[0050] The conductive polymer may be included in the solid electrolyte layer 12 together with the dopant. The dopant may be a single-molecule anion or a polymer anion. Examples of single-molecule anions include p-toluenesulfonic acid and naphthalenesulfonic acid. Examples of polymer anions include polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacrylicsulfonic acid, polymethacrylatesulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprenesulfonic acid, and polyacrylic acid. The above dopants may be used individually or in combination of two or more. Furthermore, the polymer anion may be a polymer of a single monomer or a copolymer of two or more monomers.

[0051] The solid electrolyte layer 12 may optionally contain known additives and known conductive materials other than conductive polymers. Examples of conductive materials include at least one selected from the group consisting of conductive inorganic materials such as manganese dioxide and TCNQ (tetracyanoxydimethane) complex salts.

[0052] Conductive polymers can be obtained by chemical oxidation polymerization or electrolytic polymerization of monomers (hereinafter also simply referred to as monomers) that constitute the conductive polymer.

[0053] Chemical oxidation polymerization can be carried out by chemically oxidizing monomers using a solvent, oxidizing agent, monomer, and, if necessary, a dopant. Suitable solvents include, for example, water, sulfuric acid, methanol, ethanol, propanol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, tetrahydrofuran, N-methyl-2-pyrrolidone, and propylene carbonate. The monomer and dopant should be appropriately selected depending on the desired conductive polymer. Suitable oxidizing agents include, for example, ferric oxide, iron(III) tri(p-toluenesulfonate), sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, and potassium permanganate. The polymerization conditions for chemical oxidation polymerization can be appropriately selected depending on the type of solvent, oxidizing agent, monomer, and, if necessary, dopant used.

[0054] In electropolymerization, a conductive polymer is obtained by polymerizing monomers in a solvent. Dopants may be used in electropolymerization as needed. The solvents exemplified above can be used. The monomers and dopants should be appropriately selected depending on the desired conductive polymer.

[0055] Electropolymerization methods include a method in which monomers and, if necessary, dopants are dissolved in a solvent (hereinafter referred to as the monomer-containing solvent) and a method in which monomers are polymerized by applying a potentiometer sweep method or a constant voltage method using a potentiostat, and a method in which monomers are polymerized by applying a constant current method using a galvanostat to the monomer-containing solvent. The dopant functions as an electrolyte in the monomer-containing solvent. The conditions for the potentiometer sweep method, constant voltage method, and constant current method can be appropriately selected depending on the type of solvent, monomer, and, if necessary, dopant used.

[0056] (Cathode Extraction Layer) As described above, the cathode extraction layer 13 covers at least a portion of the solid electrolyte layer 12. The cathode extraction layer 13 may cover the entire surface of the solid electrolyte layer 12. The cathode extraction layer 13 may include, for example, a carbon layer and a metal (e.g., silver) paste layer formed on the surface of the carbon layer. The configuration of the cathode extraction layer 13 is not limited to this, and it is sufficient as long as it is configured to have a current collection function. When the cathode extraction layer 13 includes a carbon layer and a metal paste layer, the carbon layer is laminated on the solid electrolyte layer 12.

[0057] The carbon layer contains a carbon material and is electrically conductive. The carbon material is not particularly limited; examples of carbon materials include graphite, carbon black, graphene flakes, and carbon nanotubes.

[0058] The carbon layer may optionally contain at least one of a binder resin and an additive. The binder resin is not particularly limited, and known binder resins used in the fabrication of capacitor elements can be used. Examples of binder resins include thermosetting resins and thermoplastic resins. Examples of thermosetting resins include epoxy resins, polyimide resins, silicon resins, phenolic resins, urea resins, melamine resins, unsaturated polyester resins, and curable acrylic resins. Examples of thermoplastic resins include polyamide resins, polyamide-imide resins, polyolefin resins, and polyester resins. Examples of additives include dispersants, surfactants, antioxidants, preservatives, bases, and acids.

[0059] The metal paste layer contains a metal material. The metal material is not particularly limited. From the viewpoint of improving conductivity, it is preferable that the metal material contains silver.

[0060] The volume ratio of the metal material in the metal paste layer is not particularly limited as long as it is greater than 0 volume%. From the viewpoint of reducing electrical resistance, the volume ratio of the metal material is preferably 60 volume% or more, more preferably 70 volume% or more, and even more preferably 80 volume% or more.

[0061] The metal paste layer may further contain a binder resin. The volume ratio of the binder resin in the metal paste layer is not particularly limited. From the viewpoint of reducing electrical resistance, the volume ratio of the binder resin is preferably 60 vol% or less, more preferably 20 vol% or less, and even more preferably 10 vol% or less. The volume ratio of the binder resin may be 0.1 vol% or more, or it may be 0 vol%. The volume ratio of the binder resin can be confirmed, for example, by energy-dispersive X-ray spectroscopy (SEM-EDX).

[0062] The thickness of the metal paste layer is not particularly limited. For example, the thickness of the metal paste layer may be 0.1 μm or more and 50 μm or less, or 1 μm or more and 20 μm or less. The thickness of the metal paste layer is the average value of any five points in the cross-section in the thickness direction.

[0063] (Solid Electrolytic Capacitor) Figure 3 is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to one embodiment of the present disclosure. Note that the cathode portion 14 is not shown in Figure 3. Figure 4A is a perspective view of the solid electrolytic capacitor shown in Figure 3, viewed from the anode side, with the first external electrode not attached. Figure 4B is a perspective view of the solid electrolytic capacitor shown in Figure 3, viewed from the cathode side, with the first external electrode not attached.

[0064] As shown in Figure 3, in the solid electrolytic capacitor 100, multiple capacitor elements 10 are stacked in the height direction D2 with their main surfaces overlapping. The multiple capacitor elements 10 are stacked such that in the first direction D1, the end faces of the anode bodies 11 are facing the same direction. More specifically, the protruding ends of the first anode body portion 11a of the anode body 11 are facing the same direction. Furthermore, as will be described later, in the solid electrolytic capacitor 100, the entirety of the multiple capacitor elements 10 is covered by an outer casing 120. In other words, the solid electrolytic capacitor 100 has an element stack 10A in which multiple capacitor elements 10 are stacked, the outer casing 120 seals the element stack 10A, and in the element stack 10A, each of the protruding ends of the first anode body portion 11a of the anode body 11 faces the third surface S3 of the outer casing 120.

[0065] The number of stacked capacitor elements 10 is not particularly limited. For example, the number of stacked capacitor elements 10 is between 2 and 20. Figure 3 shows an example in which four capacitor elements 10 are stacked.

[0066] The lead frame 110 is electrically connected to each of the cathode portions of the multiple capacitor elements 10. The lead frame 110 extends along the first surface S1 of the housing and is electrically connected to the cathode portion 14 of the capacitor element located on the first surface side of the element stack 10A on the first surface S1 side of the housing, and a portion of it rises toward the second surface S2 and is electrically connected to the end face of the cathode portion 14 of the capacitor element 10. A portion (protruding portion) 112 of the lead frame 110 extends toward the fourth surface S4 of the housing without rising toward the second surface S2, and the end face of the portion 112 of the lead frame 110 is exposed on the fourth surface S4. The housing 120 seals the multiple capacitor elements 10 and the lead frame 110.

[0067] The third surface S3 of the exterior body has an acute angle θ1 with the first surface S1. The fourth surface S4 of the exterior body has an acute angle θ2 with the first surface S1. As a result, as shown in Figure 3, the exterior body 120 has a trapezoidal cross-sectional shape.

[0068] The solid electrolytic capacitor 100 includes a first external electrode 130 electrically connected to each of the first anode portions 11a of the plurality of capacitor elements 10, and a second external electrode 140 electrically connected to the lead frame 110.

[0069] In the element stack 10A, the protruding ends of the first anode portion 11a of the anode body 11 are exposed from the third surface S3 of the outer casing 120. Also, a part 112 of the lead frame 110, which is electrically connected to the cathode portion 14, is exposed from the fourth surface S4 of the outer casing 120. Together with the cathode portion 14, the lead frame 110 can be said to constitute a common cathode portion for each of the capacitor elements constituting the element stack 10A. That is, the solid electrolytic capacitor 100 has a configuration in which the end face of the anode portion is exposed from the outer casing 120 on the third surface S3 and electrically connected to the first external electrode 130, and the end face of the lead frame 110 that constitutes the cathode portion is exposed from the outer casing 120 on the fourth surface S4 and electrically connected to the second external electrode 140.

[0070] A contact layer (conductive coating) 30 may be formed on the end face of the anode portion exposed on the third surface S3, and / or on the end face of the cathode portion exposed on the fourth surface S4. The contact layer may be formed by cold spray treatment or by AD method. The contact layer 30 functions as an internal electrode of the solid electrolytic capacitor 100. Furthermore, by forming the contact layer 30, spontaneous oxidation of the end face of the first anode portion 11a can be suppressed. In addition, since the conductive coating has an uneven surface, adhesion to the external electrode is improved by an anchoring effect. Conductive particles such as copper (Cu), aluminum (Al), titanium (Ti), silver (Ag), nickel (Ni), zinc (Zn), tin (Sn), molybdenum (Mo), iron (Fe), tantalum (Ta), niobium (Nb), silicon (Si), and chromium (Cr) can be used in the cold spray treatment or AD method.

[0071] (Outer covering) The outer covering 120 protects the multiple capacitor elements 10 from impact and moisture. The outer covering 120 is configured to cover the entirety of the multiple capacitor elements 10. The outer covering 120 may be made of resin or other materials. The outer covering 120 is preferably made of resin. For example, epoxy resin can be used as the material for the resin outer covering.

[0072] If the outer casing 120 is a resin outer casing, an inorganic filler may be included in the outer casing 120. This can increase the strength of the outer casing 120. Examples of inorganic fillers include the insulating particles described above.

[0073] The average particle size of inorganic fillers is, for example, between 60 μm and 80 μm. The average particle size of inorganic fillers can be measured by centrifugal sedimentation or laser diffraction. Average particle size measurement by centrifugal sedimentation can be performed using a Beckmann-Coaster ultracentrifugal sedimentation particle size distribution analyzer. The average particle size determined by laser diffraction is the median diameter at which the integrated volume value reaches 50% in volume-based particle size distribution measurement.

[0074] (First and Second External Electrodes) The first external electrode 130 and the second external electrode 140 can be obtained by applying a conductive paste containing conductive particles (e.g., silver particles) to the third surface S3 and the fourth surface S4 of the outer casing 120, drying it to form a conductive paste layer, and then plating the conductive paste layer with a metal (e.g., nickel) to form a metal plating layer. In the solid electrolytic capacitor 100, the first external electrode 130 is configured to cover the third surface S3 of the outer casing 120, and the second external electrode 140 is configured to cover the fourth surface S4 of the outer casing 120.

[0075] (Lead frame) The lead frame 110 has a side wall portion 111 that extends along the fourth surface S4 of the outer casing 120. In the first direction D1, the side wall portion 111 faces the end face of the cathode portion 14 of the capacitor element on the fourth surface S4 side. The lead frame 110 also has a protruding portion 112 that intersects with the side wall portion 111 and extends toward the fourth surface S4 of the outer casing 120, and is exposed on the fourth surface S4. The lead frame 110 is electrically connected to the second external electrode 140 via the protruding portion 112. In other words, on the fourth surface S4 of the outer casing 120, the end face of the protruding portion 112 of the lead frame 110 is exposed and electrically connected to the second external electrode 140.

[0076] The side wall portion 111 of the lead frame 110 and the plurality of capacitor elements 10 are connected by a first conductive paste layer (not shown). This allows for electrical connection between each of the cathode portions of the plurality of capacitor elements 10 and the side wall portion 111 of the lead frame 110. More specifically, the side wall portion 111 of the lead frame 110 can be electrically connected to each of the end faces on the fourth surface S4 side of the cathode portion 14 of the plurality of capacitor elements 10. Furthermore, the fourth surface S4 of the outer casing 120 and the second external electrode 140 are also connected by a second conductive paste layer. This allows for electrical connection between the second external electrode 140 and the protruding portion 112 of the lead frame 110. The first conductive paste layer and the second conductive paste layer can be formed using various known conductive adhesives.

[0077] As shown in Figures 3 and 4B, the lead frame 110 has a pair of protruding portions 112 spaced apart from each other, and the side wall portion 111 extends from between the pair of protruding portions 112 toward the fourth surface S4 of the cathode portion along the fourth surface S4 of the outer casing 120. With the solid electrolytic capacitor 100 configured as described above, the contact area between the second external electrode 140 and the lead frame 110 can be increased. This allows for a more favorable electrical connection between the lead frame 110 and the second external electrode 140.

[0078] The end of the side wall portion 111 may be further bent toward the fourth surface S4 to form a protruding portion 114 separate from the protruding portion 112. On the fourth surface S4, the end face of the protruding portion 114 can be exposed together with the end face of the protruding portion 112 and electrically connected to the second external electrode 140. In this case, an example of a perspective view of the solid electrolytic capacitor as seen from the cathode side is shown in Figure 4C.

[0079] The lead frame 110 may further include a bottom plate portion 113 that extends in a first direction D1 along the lower end surface of the cathode portion and is connected to the side wall portion 111 and the overhang portion 112. When the lead frame 110 is configured as described above, the bottom plate portion 113 can adequately support a plurality of capacitor elements 10 from below. The bottom plate portion 113 may be connected to the lower end surface of the cathode portion of the capacitor element 10 by a conductive paste layer (not shown). When configured in this way, the lower end surface of the capacitor element 10 can also be electrically connected to the lead frame 110. That is, the bottom plate portion 113 of the lead frame 110 can be electrically connected so as to be in contact with the lower end surface of the cathode portion.

[0080] Next, a method for manufacturing a solid electrolytic capacitor according to one embodiment of the present disclosure will be described.

[0081] A method for manufacturing a solid electrolytic capacitor according to one embodiment of the present disclosure includes: a first step of preparing an anode body having a roughened portion extending from at least one outer surface toward the center in the thickness direction and a core portion continuous with the roughened portion in the thickness direction; a second step of forming a dielectric layer so as to cover at least a part of the anode body; a third step of compressing a part of the anode body having the roughened portion in the thickness direction to form a thin-walled portion and placing a separating member in this thin-walled portion; a fourth step of covering at least a part of the dielectric layer so as to expose the thin-walled portion and the insulating member to form a cathode portion, thereby obtaining a laminate in which the anode body, dielectric layer and cathode portion are stacked in this order; and a side wall portion and extending in a direction intersecting the side wall portion. The method includes: a fifth step of placing a laminate on a lead frame having an overhang portion, with the side wall portion of the lead frame and the end face of the cathode portion electrically connected, and sealing the lead frame and the laminate to obtain a seal; a sixth step of exposing the tip end face of the anode body and the end face of the separation member from the first end face of the seal, and exposing the tip end face of the overhang portion of the lead frame from the second end face of the seal; a seventh step of forming a conductive coating on the tip end face of the anode body; and an eighth step of arranging a first external electrode so as to be electrically connected to the tip end face of the anode body exposed from the first end face of the seal, and arranging a second external electrode so as to be electrically connected to the overhang portion of the lead frame exposed from the second end face of the seal.

[0082] In the first step, the roughened portion can be formed by performing an etching treatment or the like on at least one outer surface of the anode body. The outer surface of the anode body refers to the main surface of the anode body. In the first step, it is preferable to perform an etching treatment or the like on each of the outer surfaces of the anode body to form a roughened portion on the anode body that extends from each of the outer surfaces toward the center in the thickness direction. In the anode body, the area where the etching treatment or the like has not been performed may be the core. The etching treatment may also be electrolytic etching.

[0083] In the second step, the dielectric layer can be formed by various known methods. The dielectric layer can be formed by oxidizing the valve metal contained in the anode body by chemical conversion treatment or the like. For example, the dielectric layer may be formed by immersing the anode body in a chemical conversion solution and applying a voltage. In the method for manufacturing a solid electrolytic capacitor according to one embodiment of the present disclosure, as described above, the anode body has a roughened surface. Therefore, the dielectric layer may be formed on the outer surface of the roughened surface, or it may be formed along the inner wall surface of a plurality of fine pores in the roughened surface. The dielectric layer is usually formed over almost the entire surface of the anode body. That is, the dielectric layer is usually formed on both the first anode body portion and the second anode body portion.

[0084] In the third step, the thin-walled portion is formed by compressing a part of the anode body having a roughened portion in the thickness direction. The pressure applied when compressing a part of the anode body in the thickness direction can be appropriately adjusted considering the porosity of the roughened portion before compression and the porosity of the target thin-walled portion. In the second step, the anode body is divided into a first anode body portion having a thin-walled portion and a second anode body portion not having a thin-walled portion. The first anode body portion is a region of the anode body that does not have a cathode portion containing a solid electrolyte layer, and the second anode body portion is a region of the anode body that has a cathode portion containing a solid electrolyte layer.

[0085] In the fourth step, the cathode portion can be formed by various known methods. The solid electrolyte layer in the cathode portion can be formed, for example, by attaching a monomer of a conductive polymer (hereinafter simply referred to as monomer) to at least a part of the dielectric layer, and then chemically oxidatively polymerizing or electrolytically polymerizing the monomer in at least a part of the dielectric layer to form a conductive polymer layer. The attachment of monomer to at least a part of the dielectric layer can be carried out by immersing at least a part of the anode body, on which the dielectric layer is formed, in a polymerization solution containing monomer. In a method for manufacturing a solid electrolytic capacitor according to one embodiment of the present disclosure, a conductive polymer layer is formed on the second anode body by attaching the monomer to the dielectric layer formed on the second anode body. When electrolytically polymerizing the monomer, a voltage in the range of 1 to 5 V may be applied to the anode body as electrical energy.

[0086] The solid electrolyte layer in the cathode may be formed by applying a treatment solution containing a conductive polymer onto the dielectric layer to form a coating, and then drying this coating. For example, poly(3,4-ethylenedioxythiophene) (PEDOT) can be used as the conductive polymer. For example, polystyrene sulfonic acid (PSS) can be used as the dopant. The treatment solution is a dispersion or solution of the conductive polymer. Examples of dispersion media (solvents) include water, organic solvents, or mixtures thereof.

[0087] The cathode extraction layer in the cathode section can be obtained, for example, by applying a carbon dispersion liquid in which carbon is dispersed so as to cover at least a portion of the solid electrolyte layer, drying it to form a carbon layer, and then applying a composition containing metal particles (e.g., silver particles) and a resin component (binder resin) so as to cover at least a portion of the carbon layer, and then heating and drying it to form a conductive layer. If the binder resin is a thermosetting resin, the binder resin can be heat-cured by the above heating and drying process. In this way, a laminate can be obtained in which the anode, dielectric layer, and cathode section are stacked in this order.

[0088] In the fifth step, a lead frame having a side wall and an overhang extending in a direction intersecting the side wall can be obtained by processing a metal plate into a predetermined shape. Preferably, the lead frame further comprises a bottom plate connected to the side wall and the overhang, in addition to the side wall and the overhang. The presence of the bottom plate in the lead frame allows the laminate obtained as described above to be adequately supported from below. Preferably, the bottom plate extends in the same direction as the overhang extends. That is, preferably, the bottom plate extends in a direction intersecting the side wall.

[0089] The sidewall portion of the lead frame and the end face of the cathode portion can be electrically connected, for example, by interposing a conductive paste layer between them. The lead frame and laminate are sealed by embedding the entire lead frame and laminate with, for example, a sealing resin. If the sealing resin is a thermosetting resin, it is preferable that the sealing resin be thermoset after the lead frame and laminate have been embedded. Conventional known techniques such as transfer molding or compression molding can be applied to seal with the sealing resin.

[0090] In the sixth step, the first and second end faces of the encapsulant are cut by a predetermined dimension, for example, by blade dicing or by using an ultrasonic cutter, so that the tip face of the anode body and the tip face of the protruding portion of the lead frame are exposed. In the manufacturing method of a solid electrolytic capacitor according to one embodiment of this disclosure, the tip face of the anode body refers to the tip face of the first anode body portion. After cutting, the tip face of the anode body and the end face of the separation member are exposed from the first end face of the encapsulant, and the tip face of the protruding portion of the lead frame is exposed from the second end face of the encapsulant after cutting.

[0091] In the seventh step, a conductive coating (contact layer) is formed on the tip surface of the anode body at the first end face of the sealed body after cutting. The conductive coating can be formed by cold spray treatment or AD method, as described above. Alternatively, in the seventh step, a conductive coating may be formed on the tip surface of the protruding portion of the lead frame by performing cold spray treatment or AD method on the second end face of the sealed body after cutting.

[0092] In the eighth step, the first external electrode can be obtained by applying a conductive paste containing conductive particles (e.g., silver particles) to the first end face of the cut sealant to form a conductive paste layer, and then plating a metal (e.g., nickel) onto the conductive paste layer to form a metal plating layer. The second external electrode can also be obtained in the same manner as above by forming a conductive paste layer and a metal plating layer in this order on the second end face of the cut sealant. The first external electrode obtained in this manner is electrically connected to the tip end face of the anode body (i.e., the tip end face of the first anode body portion), and the second external electrode obtained in this manner is electrically connected to the tip end face of the protruding portion of the lead frame.

[0093] As described above, by carrying out steps 1 to 8, a solid electrolytic capacitor according to one embodiment of the present disclosure can be obtained.

[0094] In this specification, an example has been described in which a solid electrolytic capacitor 100 comprises multiple capacitor elements 10, but the number of capacitor elements 10 in the solid electrolytic capacitor 100 may be just one.

[0095] Furthermore, in this specification, as one embodiment, a solid electrolytic capacitor 100 has an element stack 10A in which a plurality of capacitor elements 10 are stacked, an outer casing 120 seals the element stack 10A, and in the element stack 10A, each of the protruding ends of the first anode portion 11a of the anode body 11 faces the third surface S3 on one side of the outer casing 120, and each of the end faces of the cathode portion faces the fourth surface S4 on the other side of the outer casing 120. However, the configuration of the solid electrolytic capacitor 100 is not limited to this. For example, in the solid electrolytic capacitor 100, an element stack may be constructed by alternately stacking a first capacitor element in which the protruding end of the first anode portion 11a of the anode body 11 faces the third surface S3 of the outer casing 120, and a second capacitor element in which the protruding end of the first anode portion 11a of the anode body 11 faces the fourth surface S4 of the outer casing 120.

[0096] Furthermore, in this specification, as one embodiment, an example has been described in which the protruding ends of the first anode portion 11a are exposed on the third surface S3 of the outer casing 120, and the protruding portions 112 of the lead frame 110, which are electrically connected to each of the cathode portions, are exposed on the fourth surface S4 of the outer casing 120. However, the configuration of the solid electrolytic capacitor 100 is not limited to this. For example, in the element stack 10A, cathode foils may be interposed between the cathode portions of the capacitor elements, and the end faces of the cathode foils may be exposed on the fourth surface S4 of the outer casing 120. Note that since the cathode foil is also a component of the cathode portion, the end face of the cathode portion also includes the end face of the cathode foil.

[0097] (Note) The following technologies are disclosed by the above description. (Technology 1) A solid electrolytic capacitor comprising: a capacitor element having an anode portion and a cathode portion; an outer casing that encloses the capacitor element; a first external electrode electrically connected to the anode portion; and a second external electrode electrically connected to the cathode portion, wherein the outer surface of the outer casing has a first surface, a second surface facing the first surface, and a third surface formed in a direction intersecting the first surface and the second surface, at least one of the end faces of the anode portion and the cathode portion is exposed from the outer casing on the third surface and electrically connected to the first external electrode or the second external electrode, and the angle θ1 between the third surface and the first surface is an acute angle. (Technology 2) The solid electrolytic capacitor according to Technology 1, comprising an element stack formed by stacking a plurality of the capacitor elements, wherein the outer casing encloses the element stack, and the distance between the element stack and the first surface is shorter than the distance between the element stack and the second surface. (Technology 3) A solid electrolytic capacitor according to Technology 1 or 2, wherein θ1 is 85° or more. (Technology 4) A solid electrolytic capacitor according to any one of Technology 1 to 3, wherein the outer surface of the casing is formed in a direction intersecting the first surface and the second surface and has a fourth surface facing the third surface, and the width Wb of the first surface in a first direction from the third surface toward the fourth surface is longer than the width Wt of the second surface in the first direction and is 1.05 times or less of Wt. (Technology 5) A solid electrolytic capacitor according to any one of Technology 1 to 4, wherein the third surface has a contact layer covering at least one of the end faces of the anode portion and the cathode portion, and at least one of the anode portion and the cathode portion is electrically connected to the first external electrode or the second external electrode via the contact layer. (Technology 6) A solid electrolytic capacitor according to Technology 5, wherein the contact layer is formed by a film deposition technique that causes conductive particles to physically collide with the third surface at high speed.

[0098] Although the present invention has been described in relation to preferred embodiments at present, various modifications and alterations are possible.

[0099] Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

[0100] This disclosure can be used in solid electrolytic capacitors.

[0101] 10: Capacitor element, 10A: Element stack, 11: Anode, 11a: First anode section, 11b: Second anode section, 11c: Roughened section, 11c1: Thin section, 11d: Core section, 12: Solid electrolyte layer, 13: Cathode lead-out layer, 14: Cathode section, 15: Separation member, 30: Contact layer, 100: Solid electrolytic capacitor, 111: Side wall section, 112, 114: Protruding section, 113: Bottom plate section, 120: Outer casing, 130: First external electrode, 140: Second external electrode, 200: Thermal spray nozzle, D1: First direction, D2: Height direction, S1: First surface, S2: Second surface, S3: Third surface, S4: Fourth surface

Claims

1. A solid electrolytic capacitor comprising: a capacitor element having an anode portion and a cathode portion; an outer casing that encloses the capacitor element; a first external electrode electrically connected to the anode portion; and a second external electrode electrically connected to the cathode portion, wherein the outer surface of the outer casing has a first surface, a second surface facing the first surface, and a third surface formed in a direction intersecting the first and second surfaces, at least one of the end faces of the anode portion and the cathode portion is exposed from the outer casing on the third surface and electrically connected to the first external electrode or the second external electrode, and the angle θ1 between the third surface and the first surface is acute.

2. The solid electrolytic capacitor according to claim 1, having an element stack in which a plurality of capacitor elements are stacked, wherein the outer casing seals the element stack, and the distance between the first surface of the element stack and the second surface of the element stack is shorter than the distance between the second surface of the element stack and the outer casing.

3. The solid electrolytic capacitor according to claim 1 or 2, wherein θ1 is 85° or greater.

4. The solid electrolytic capacitor according to claim 1 or 2, wherein the outer surface of the outer casing is formed in a direction intersecting the first surface and the second surface, and has a fourth surface facing the third surface, and the width Wb of the first surface in the first direction from the third surface toward the fourth surface is longer than the width Wt of the second surface in the first direction, and is 1.05 times or less of Wt.

5. The solid electrolytic capacitor according to claim 1 or 2, having a contact layer covering at least one of the end faces of the anode portion and the cathode portion on the third surface, wherein at least one of the anode portion and the cathode portion is electrically connected to the first external electrode or the second external electrode via the contact layer.

6. The solid electrolytic capacitor according to claim 5, wherein the contact layer is formed by a film deposition technique that causes conductive particles to physically collide with the third surface at high speed.

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