Solid electrolytic capacitor

Abstract

The solid electrolytic capacitor (1) has, in the thickness direction (T): a valve-action metal substrate (3a) having a porous portion (3b) on its surface; a dielectric layer (5) provided on the surface of the porous portion (3b); a solid electrolyte layer (7a) provided on the surface of the dielectric layer (5); a conductive layer (7b) provided on the surface of the solid electrolyte layer (7a); and a cathode lead-out layer (7c) provided on the surface of the conductive layer (7b). When viewed from the thickness direction (T), the solid electrolyte layer (7a) has: a central region (AR1) including the center of the solid electrolyte layer (7a); and an outer peripheral region (AR2) located around the central region (AR1) and including all of the outer edge of the solid electrolyte layer (7a). When a height in the thickness direction (T) is defined with respect to a reference plane (S) that includes the highest point (P) of the porous portion (3b) in the thickness direction (T) and is orthogonal to the thickness direction (T), the outer peripheral region (AR2) is higher than the central region (AR1) throughout the periphery of the central region (AR1). The conductive layer (7b) is provided on at least the central region (AR1) of the solid electrolyte layer (7a).

Description

Technical Field

[0001] The present invention relates to a solid electrolytic capacitor. Background Art

[0002] A solid electrolytic capacitor is manufactured, for example, by forming a dielectric layer on the surface of an anode containing a valve metal, and then forming a cathode so as to face the anode with the dielectric layer therebetween. When forming the cathode, for example, a solid electrolyte layer is formed on the surface of the dielectric layer, and then a conductive layer (also referred to as a conductor layer) is formed on the surface of the solid electrolyte layer.

[0003] For example, Patent Document 1 discloses a method for manufacturing a solid electrolytic capacitor, which includes: a step of preparing a first sheet; a step of preparing a second sheet; a step of coating the first sheet with an insulating material; a step of forming a conductor layer on the first sheet; a step of manufacturing a laminated sheet; a step of manufacturing a laminated block; a step of manufacturing a plurality of element laminates by cutting the laminated block; and a step of forming a first external electrode and a second external electrode.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-79866 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In the method for manufacturing a solid electrolytic capacitor described in Patent Document 1, a conductive paste is applied onto a solid electrolyte layer of a first sheet having a valve metal substrate with a dielectric layer formed on its surface, thereby forming a conductor layer, and then a second sheet made of a metal foil is laminated. However, if the second sheet is laminated in a state where the coating amount of the conductive paste constituting the conductor layer is large, or if the second sheet is laminated with a strong pressing force, there is a concern that the conductor layer is extruded and diffused on the first sheet and leaks to the outside. Therefore, there is a concern that the long-term reliability decreases due to deterioration caused by intrusion of moisture from the outside due to a sealing defect in the obtained solid electrolytic capacitor, or that the quality deteriorates due to dissolution of internal materials caused by intrusion of a plating solution when forming an external electrode. On the other hand, if the second sheet is laminated in a state where the coating amount of the conductive paste constituting the conductor layer is small, or if the second sheet is laminated with a low pressing force in order not to allow the conductor layer to leak, the conductor layer is not extruded and diffused on the first sheet, and the contact area between the solid electrolyte layer and the conductor layer becomes small. Therefore, there is a concern that the resistance of the obtained solid electrolytic capacitor becomes high.

[0009] The present invention is completed to solve the above problems, and its object is to provide a solid electrolytic capacitor capable of achieving low resistance while preventing leakage of the conductive layer.

[0010] Technical solution for solving the problem

[0011] The solid electrolytic capacitor of the present invention is characterized in that, in the thickness direction, it includes: a valve-acting metal substrate having a porous portion on the surface; a dielectric layer provided on the surface of the porous portion; a solid electrolyte layer provided on the surface of the dielectric layer; a conductive layer provided on the surface of the solid electrolyte layer; and a cathode lead-out layer provided on the surface of the conductive layer. When viewed from the thickness direction, the solid electrolyte layer has: a central region including the center of the solid electrolyte layer; and an outer peripheral region located around the central region and including all of the outer edge of the solid electrolyte layer. When defining the height in the thickness direction with respect to a reference plane that includes the highest point of the porous portion in the thickness direction and is orthogonal to the thickness direction, the outer peripheral region is higher than the central region around the central region, and the conductive layer is provided on at least the central region of the solid electrolyte layer.

[0012] Effect of the invention

[0013] According to the present invention, it is possible to provide a solid electrolytic capacitor capable of achieving low resistance while preventing leakage of the conductive layer. Description of the drawings

[0014] Figure 1 It is a perspective schematic view showing a solid electrolytic capacitor according to Embodiment 1 of the present invention.

[0015] Figure 2 It shows Figure 1 A cross-sectional schematic view of a portion corresponding to the line segment A1 - A2 in

[0016] Figure 3 It is to Figure 1 A perspective schematic view showing a part of the resin molded body shown decomposed.

[0017] Figure 4 It shows Figure 3 A perspective schematic view showing the state after removing the conductive layer and the cathode lead-out layer.

[0018] Figure 5 It shows Figure 3 A partial cross-sectional schematic view of a portion corresponding to the line segment B1 - B2 in

[0019] Figure 6 It is a cross-sectional schematic view showing a solid electrolytic capacitor according to a modified example of Embodiment 1 of the present invention.

[0020] Figure 7 This is a schematic cross-sectional view showing a part of the resin molded body in the solid electrolytic capacitor of Embodiment 2 of the present invention. Detailed Embodiments

[0021] Hereinafter, the solid electrolytic capacitor of the present invention will be described. In addition, the present invention is not limited to the following structure, and can be appropriately changed without departing from the gist of the present invention. In addition, a structure in which a plurality of the following described preferred structures are combined is also the present invention.

[0022] It is self-evident that each of the following embodiments is an exemplification, and partial replacement or combination of the structures shown in different embodiments can be performed. After Embodiment 2, the description of matters common to Embodiment 1 is omitted, and the differences will be mainly described. In particular, the same effects based on the same structure are not mentioned successively in each embodiment. In the following description, without particularly distinguishing each embodiment, it is simply referred to as "the solid electrolytic capacitor of the present invention".

[0023] [Embodiment 1]

[0024] Figure 1 This is a three-dimensional schematic view showing the solid electrolytic capacitor of Embodiment 1 of the present invention.

[0025] As Figure 1 shown, the solid electrolytic capacitor 1 has a resin molded body 9, a first external electrode 11, and a second external electrode 13.

[0026] In this specification, as Figure 1 etc. shown, the length direction, the thickness direction, and the width direction are set as the directions defined by L, T, and W respectively. Here, the length direction L, the thickness direction T, and the width direction W are orthogonal to each other.

[0027] The resin molded body 9 is substantially rectangular parallelepiped, and has a first end face 9a and a second end face 9b opposed to each other in the length direction L, a first main face 9c and a second main face 9d opposed to each other in the thickness direction T, and a first side face 9e and a second side face 9f opposed to each other in the width direction W.

[0028] The first end face 9a and the second end face 9b of the resin molded body 9 do not need to be strictly orthogonal to the length direction L. In addition, the first main face 9c and the second main face 9d of the resin molded body 9 do not need to be strictly orthogonal to the thickness direction T. Further, the first side face 9e and the second side face 9f of the resin molded body 9 do not need to be strictly orthogonal to the width direction W.

[0029] The first external electrode 11 is provided on the first end face 9a of the resin molded body 9. The first external electrode 11 may also extend from the first end face 9a of the resin molded body 9 to a part of each of at least one of the first main face 9c, the second main face 9d, the first side face 9e, and the second side face 9f.

[0030] The second external electrode 13 is provided on the second end face 9b of the resin molded body 9. The second external electrode 13 extends from the second end face 9b of the resin molded body 9 to a part of each of at least one of the first main face 9c, the second main face 9d, the first side face 9e, and the second side face 9f.

[0031] Figure 2 is a cross-sectional schematic view showing Figure 1 the part corresponding to the line segment A1 - A2 in

[0032] As Figure 2 shown, the resin molded body 9 has a plurality of capacitor elements 20 and a sealing resin 8 that seals the periphery of the plurality of capacitor elements 20. More specifically, the resin molded body 9 has a laminate 30 formed by laminating a plurality of capacitor elements 20 in the thickness direction T and a sealing resin 8 that seals the periphery of the laminate 30.

[0033] In the laminate 30, the capacitor elements 20 may also be joined to each other via a conductive adhesive layer.

[0034] The resin molded body 9 preferably has a plurality of capacitor elements 20, but may also have one capacitor element 20.

[0035] A support substrate such as a glass epoxy substrate may also be provided at the bottom of the resin molded body 9. In the case where the support substrate is provided, the bottom surface of the support substrate constitutes the first main face 9c of the resin molded body 9.

[0036] The capacitor element 20 has an anode 3, a dielectric layer 5, and a cathode 7. The anode 3 and the cathode 7 are opposed to each other with the dielectric layer 5 therebetween. The anode 3 is exposed from the first end face 9a of the resin molded body 9. The cathode 7 (here, the cathode lead layer 7c described later) is exposed from the second end face 9b of the resin molded body 9.

[0037] The anode 3 has a valve - acting metal substrate 3a at the center.

[0038] As the valve - acting metal constituting the valve - acting metal substrate 3a, for example, metal elements such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, and silicon, alloys containing at least one of these metal elements, etc. can be cited. Among them, aluminum or aluminum alloy is particularly preferred.

[0039] The shape of the valve - acting metal substrate 3a is preferably a flat plate shape, and more preferably a foil shape.

[0040] The valve-acting metal substrate 3a has a porous portion 3b on its surface.

[0041] The porous portion 3b is preferably an etched layer obtained by etching the valve-acting metal substrate 3a with hydrochloric acid or the like.

[0042] The thickness of the valve-acting metal substrate 3a before the etching treatment is preferably 60 μm or more, and further preferably 180 μm or less. In the state after the etching treatment, the thickness of the core portion of the valve-acting metal substrate 3a that is not etched is preferably 10 μm or more, and further preferably 70 μm or less. The thickness of the porous portion 3b is designed in accordance with the withstand voltage, capacitance, etc. required for the solid electrolytic capacitor 1. In the Figure 2 shown cross-section, the total thickness of the porous portions 3b provided on both sides of the valve-acting metal substrate 3a is preferably 10 μm or more, and further preferably 120 μm or less. In addition, the porous portion 3b may be provided on one main surface of the valve-acting metal substrate 3a.

[0043] The dielectric layer 5 is provided on the surface of the porous portion 3b.

[0044] The dielectric layer 5 is preferably composed of an oxide film of the above-described valve-acting metal. For example, when the valve-acting metal substrate 3a is an aluminum foil, an oxide film that becomes the dielectric layer 5 is formed by anodizing the valve-acting metal substrate 3a in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or their sodium salts, ammonium salts, etc. Since the dielectric layer 5 is formed along the surface of the porous portion 3b, as a result, fine pores (recesses) are provided in the dielectric layer 5.

[0045] The thickness of the dielectric layer 5 is designed in accordance with the withstand voltage, capacitance, etc. required for the solid electrolytic capacitor 1, and is preferably 10 nm or more, and further preferably 100 nm or less.

[0046] The cathode 7 has a solid electrolyte layer 7a, a conductive layer 7b, and a cathode lead-out layer 7c.

[0047] The solid electrolyte layer 7a is provided on the surface of the dielectric layer 5.

[0048] As a constituent material of the solid electrolyte layer 7a, for example, conductive polymers having a skeleton of pyrrole, thiophene, aniline, etc. can be cited. As a conductive polymer having a skeleton of thiophene, for example, poly(3,4-ethylenedioxythiophene) (PEDOT) can be cited, and it may also be PEDOT:PSS that is complexed with polystyrene sulfonic acid (PSS) as a dopant.

[0049] The solid electrolyte layer 7a is formed, for example, by a method of forming a polymer film such as poly(3,4-ethylenedioxythiophene) on the surface of the dielectric layer 5 using a treatment liquid containing monomers such as 3,4-ethylenedioxythiophene, or by a method of drying after coating a dispersion liquid of a polymer such as poly(3,4-ethylenedioxythiophene) on the surface of the dielectric layer 5. The solid electrolyte layer 7a is coated on the surface of the dielectric layer 5 by a method such as screen printing, sponge transfer printing, inkjet printing, dip coating, dispenser coating, spray coating, etc., preferably by screen printing, so as to form in a given area. In addition, as the solid electrolyte layer 7a, it is preferable to form a solid electrolyte layer for the inner layer that fills the pores (recesses) of the dielectric layer 5 first, and then form a solid electrolyte layer for the outer layer that covers the entire dielectric layer 5.

[0050] The morphology of the solid electrolyte layer 7a will be described later.

[0051] The conductive layer 7b is provided on the surface of the solid electrolyte layer 7a.

[0052] The conductive layer 7b is formed, for example, by coating a conductive paste such as carbon paste, graphene paste, or silver paste on the surface of the solid electrolyte layer 7a by a method such as screen printing, sponge transfer printing, inkjet printing, dip coating, dispenser coating, spray coating, etc.

[0053] The conductive layer 7b is preferably a carbon layer, a graphene layer, or a silver layer formed by the above method. In addition, the conductive layer 7b can also be a composite layer with a silver layer provided on a carbon layer or a graphene layer, or a mixed layer of carbon paste or graphene paste and silver paste.

[0054] The thickness of the conductive layer 7b is preferably 2 μm or more, and in addition, preferably 20 μm or less.

[0055] The cathode lead-out layer 7c is provided on the surface of the conductive layer 7b.

[0056] The cathode lead-out layer 7c is composed of, for example, a metal foil, a resin electrode layer, etc.

[0057] When the cathode lead-out layer 7c is a metal foil, the metal foil preferably contains at least one metal selected from the following group, which includes aluminum, copper, silver, and an alloy containing at least one of these metals as a main component. If the metal foil contains the above metals, the resistance of the metal foil becomes low, and the equivalent series resistance (ESR) of the solid electrolytic capacitor 1 easily becomes low.

[0058] As the metal foil, for example, a metal foil with carbon plating, titanium plating, etc. performed on the surface by a film formation method such as sputtering, evaporation, etc. can also be used. Among them, an aluminum foil with carbon plating is particularly preferably used.

[0059] From the viewpoints of improving the operability, miniaturization, and reducing the ESR in the manufacturing process, the thickness of the metal foil is preferably 20 μm or more, and further preferably 50 μm or less.

[0060] When the cathode lead-out layer 7c is a resin electrode layer, the resin electrode layer is formed, for example, by coating a conductive paste containing a conductive component and a resin component on the surface of the conductive layer 7b by a method such as screen printing, sponge transfer printing, inkjet printing, dip coating, dispenser coating, spraying, etc.

[0061] The conductive paste used in forming the cathode lead-out layer 7c preferably contains silver, copper, or nickel as the main component of the conductive component.

[0062] When forming the cathode lead-out layer 7c by the printing method as described above, it can be made thinner than the metal foil. For example, when forming the cathode lead-out layer 7c by screen printing, the thickness can be set to 20 μm or less.

[0063] The cathode lead-out layer 7c is preferably formed on the surface of the conductive layer 7b in a sticky state before the conductive layer 7b is dried.

[0064] The cathode lead-out layer 7c is preferably joined to the dielectric layer 5 via the insulating adhesive layer 10. Thereby, it becomes easy to fix the position of the cathode lead-out layer 7c.

[0065] When observed from the thickness direction T, the insulating adhesive layer 10 is preferably provided so as to surround the solid electrolyte layer 7a.

[0066] The insulating adhesive layer 10 is formed, for example, by coating an insulating material such as an insulating resin on the surface of the dielectric layer 5 in a given area.

[0067] As described above, the capacitor element 20 constituting the solid electrolytic capacitor 1 has a valve action metal substrate 3a having a porous portion 3b on the surface, a dielectric layer 5, a solid electrolyte layer 7a, a conductive layer 7b, and a cathode lead-out layer 7c in the thickness direction T.

[0068] The sealing resin 8 contains at least resin, and preferably contains resin and a filler.

[0069] As the resin in the sealing resin 8, it is preferable to use epoxy resin, phenolic resin, polyimide resin, silicone resin, polyamide resin, liquid crystal polymer, etc.

[0070] As the filler in the sealing resin 8, it is preferable to use silica particles, alumina particles, etc.

[0071] As the sealing resin 8, it is preferable to use a material containing solid epoxy resin, phenolic resin, and silica particles.

[0072] As a method for molding the resin molded body 9, in the case of using a solid sealing resin 8, resin molding such as compression molding and transfer molding is preferably used, and compression molding is more preferably used. Further, in the case of using a liquid sealing resin 8, molding methods such as dispenser coating method and printing method are preferably used. Among them, it is particularly preferable to seal the periphery of the laminate 30 with the sealing resin 8 by compression molding to form the resin molded body 9.

[0073] In the resin molded body 9, rounded corners may be provided at the corners. As a method for providing rounded corners to the corners of the resin molded body 9, for example, barrel polishing or the like can be used.

[0074] The first external electrode 11 is connected to the anode 3 exposed from the first end face 9a of the resin molded body 9.

[0075] The second external electrode 13 is connected to the cathode 7 (here, the cathode lead layer 7c) exposed from the second end face 9b of the resin molded body 9.

[0076] The first external electrode 11 and the second external electrode 13 are preferably formed by at least one method selected from the group consisting of screen printing method, sponge transfer printing method, inkjet printing method, dip coating method, dispenser coating method, spraying method, brush coating method, drop coating method, electrostatic coating method, plating method, and sputtering method.

[0077] The first external electrode 11 preferably has a resin electrode layer containing a conductive component and a resin component. Since the first external electrode 11 has a resin electrode layer, the adhesion between the first external electrode 11 and the sealing resin 8 is improved, and thus the reliability is improved.

[0078] The second external electrode 13 preferably has a resin electrode layer containing a conductive component and a resin component. Since the second external electrode 13 has a resin electrode layer, the adhesion between the second external electrode 13 and the sealing resin 8 is improved, and thus the reliability is improved.

[0079] The conductive component of the resin electrode layer preferably contains metal elements such as silver, copper, nickel, and tin, alloys containing at least one of these metal elements, etc. as the main components.

[0080] The resin component of the resin electrode layer preferably contains epoxy resin, phenolic resin, etc. as the main components.

[0081] The resin electrode layer is formed, for example, by methods such as screen printing method, sponge transfer printing method, inkjet printing method, dip coating method, dispenser coating method, spraying method, brush coating method, drop coating method, electrostatic coating method.

[0082] At least one of the first external electrode 11 and the second external electrode 13 may also have a plating layer. Examples of the plating layer include a zinc-silver-nickel plating layer, a silver-nickel plating layer, a nickel plating layer, a zinc-nickel-gold plating layer, a nickel-gold plating layer, a zinc-nickel-copper plating layer, a nickel-copper plating layer, and the like. Preferably, on these plating layers, for example, a copper plating layer, a nickel plating layer, and a tin plating layer are further provided in sequence (or, except for a part of the plating layers).

[0083] At least one of the first external electrode 11 and the second external electrode 13 may also have a resin electrode layer and a plating layer at the same time. For example, the first external electrode 11 may have a resin electrode layer connected to the anode 3 and an outer layer plating layer provided on the surface of the resin electrode layer opposite to the anode 3. In addition, the first external electrode 11 may have an inner layer plating layer connected to the anode 3, a resin electrode layer provided to cover the inner layer plating layer, and an outer layer plating layer provided on the surface of the resin electrode layer opposite to the anode 3.

[0084] Hereinafter, the form of the solid electrolyte layer 7a will be described.

[0085] Figure 3 It is Figure 1 A perspective schematic diagram showing a partial decomposition of the resin molded body shown. In Figure 3 , focusing on the arrangement of the solid electrolyte layer and the conductive layer, the state of the cathode lead-out layer being seen through is shown.

[0086] As Figure 3 shown, in the resin molded body 9, the solid electrolyte layer 7a is in a bathtub shape and has the following structure, that is, a conductive layer 7b is provided in its internal space and is covered by a cathode lead-out layer 7c. More specifically, as follows.

[0087] Figure 4 It is a perspective schematic diagram showing the state in which the conductive layer and the cathode lead-out layer are removed from Figure 3 .

[0088] As Figure 4 shown, when viewed from the thickness direction T, the solid electrolyte layer 7a has: a central region AR1 including the center of the solid electrolyte layer 7a; and a peripheral region AR2 located around the central region AR1 and including all the outer edges of the solid electrolyte layer 7a. When viewed from the thickness direction T, the outer edge of the solid electrolyte layer 7a includes a first outer edge E1 and a second outer edge E2 opposed to each other in the length direction L, and a third outer edge E3 and a fourth outer edge E4 opposed to each other in the width direction W. The center of the solid electrolyte layer 7a means the area centroid when the solid electrolyte layer 7a is projected in the thickness direction T.

[0089] The central region AR1 is defined by the following ranges.

[0090] When observing a cross-section along the length direction L and the thickness direction T, the range of the central region AR1 in the length direction L is as follows: that is, the length from the midpoint between the first outer edge E1 and the second outer edge E2 towards the first outer edge E1 and the second outer edge E2 respectively to 30% of the distance in the length direction L between the first outer edge E1 and the second outer edge E2. That is to say, in Figure 4 the solid electrolyte layer 7a shown, the length M1 of the central region AR1 in the length direction L is 60% of the distance N1 in the length direction L between the first outer edge E1 and the second outer edge E2.

[0091] When observing a cross-section along the width direction W and the thickness direction T, the range of the central region AR1 in the width direction W is as follows: that is, the length from the midpoint between the third outer edge E3 and the fourth outer edge E4 towards the third outer edge E3 and the fourth outer edge E4 respectively to 30% of the distance in the width direction W between the third outer edge E3 and the fourth outer edge E4. That is to say, in Figure 4 the solid electrolyte layer 7a shown, the length M2 of the central region AR1 in the width direction W is 60% of the distance N2 in the width direction W between the third outer edge E3 and the fourth outer edge E4.

[0092] The outer peripheral region AR2 is defined by the following ranges.

[0093] When observing a cross-section along the length direction L and the thickness direction T, the range of the outer peripheral region AR2 in the length direction L is as follows: that is, the length from the first outer edge E1 and the second outer edge E2 towards the midpoint between the first outer edge E1 and the second outer edge E2 respectively to 15% of the distance in the length direction L between the first outer edge E1 and the second outer edge E2. That is to say, in Figure 4 the solid electrolyte layer 7a shown, the length M3 of the outer peripheral region AR2 in the length direction L is 15% of the distance N1 in the length direction L between the first outer edge E1 and the second outer edge E2.

[0094] When observing a cross-section along the width direction W and the thickness direction T, the range of the outer peripheral region AR2 in the width direction W is as follows: that is, the length from the third outer edge E3 and the fourth outer edge E4 towards the midpoint between the third outer edge E3 and the fourth outer edge E4 respectively to 15% of the distance in the width direction W between the third outer edge E3 and the fourth outer edge E4. That is to say, in Figure 4 the solid electrolyte layer 7a shown, the length M4 of the outer peripheral region AR2 in the width direction W is 15% of the distance N2 in the width direction W between the third outer edge E3 and the fourth outer edge E4.

[0095] When defining the height in the thickness direction T with respect to a reference plane that includes the highest point of the porous portion 3b in the thickness direction T and is orthogonal to the thickness direction T, the outer peripheral region AR2 is higher than the central region AR1 around the central region AR1. Hereinafter, taking the case of observing a cross section along the length direction L and the thickness direction T as an example, the morphology of such a solid electrolyte layer 7a will be described.

[0096] Figure 5 is a schematic cross-sectional view showing Figure 3 a part corresponding to the line segment B1 - B2 in Figure 5 In the cross section shown along the length direction L and the thickness direction T, for the sake of convenience of explanation, it is assumed to include the highest point in the entire porous portion 3b, the highest point in the entire central region AR1, and the highest point in the entire outer peripheral region AR2.

[0097] As Figure 5 shown, when defining the height in the thickness direction T with respect to a reference plane S that includes the highest point P of the porous portion 3b in the thickness direction T and is orthogonal to the thickness direction T, the outer peripheral region AR2 is higher than the central region AR1. More specifically, the highest point Q2 of the outer peripheral region AR2 is higher than the highest point Q1 of the central region AR1. Here, the reference plane S can be defined with respect to the porous portion 3b that is closest to the solid electrolyte layer 7a to be the object in the thickness direction T.

[0098] By making the solid electrolyte layer 7a have such a morphology, even when the cathode lead-out layer 7c is laminated in a state where the coating amount of the conductive paste constituting the conductive layer 7b is large, or when the cathode lead-out layer 7c is laminated with a strong pressing force, the conductive layer 7b squeezed and diffused between the solid electrolyte layer 7a and the cathode lead-out layer 7c will be blocked by the outer peripheral region AR2 and will not leak to the outside. Therefore, the conductive layer 7b can be squeezed and diffused by the pressing force when the cathode lead-out layer 7c is laminated. As a result, the contact area between the solid electrolyte layer 7a and the conductive layer 7b can be increased. Through the above, in the solid electrolytic capacitor 1, it is possible to reduce the resistance while preventing the leakage of the conductive layer 7b.

[0099] The conductive layer 7b is provided on at least the central region AR1 of the solid electrolyte layer 7a. From the viewpoint of reducing resistance, the conductive layer 7b is preferably provided on the entire central region AR1, and more preferably extends from the central region AR1 to the outer peripheral region AR2.

[0100] On the other hand, a space U where the conductive layer 7b is not provided may exist between the solid electrolyte layer 7a and the cathode lead-out layer 7c. More specifically, a space U surrounded by the solid electrolyte layer 7a, the conductive layer 7b, and the cathode lead-out layer 7c may exist. Preferably, a space U surrounded by the outer peripheral region AR2 of the solid electrolyte layer 7a, the conductive layer 7b, and the cathode lead-out layer 7c may exist. Thus, when the solid electrolytic capacitor 1 is in a high-temperature state, for example, when the solid electrolytic capacitor 1 is mounted on a wiring board via solder and heat treatment is performed in a reflow soldering furnace, the space U functions as an expansion buffer space. That is, when the solid electrolytic capacitor 1 is in a high-temperature state, the space U can buffer a load that may cause damage to the capacitor element 20 due to interference between a plurality of members (here, members such as the solid electrolyte layer 7a, the conductive layer 7b, and the cathode lead-out layer 7c) having different linear expansion coefficients.

[0101] The height H2 of the highest point Q2 of the outer peripheral region AR2 is preferably 2 μm or more greater than the height H1 of the highest point Q1 of the central region AR1. In this case, even when the cathode lead-out layer 7c is laminated in a state where the coating amount of the conductive paste constituting the conductive layer 7b is larger, or when the cathode lead-out layer 7c is laminated with a stronger pressing force, the conductive layer 7b does not leak to the outside. Therefore, the contact area between the solid electrolyte layer 7a and the conductive layer 7b can be further increased, and as a result, the solid electrolytic capacitor 1 can be further reduced in resistance.

[0102] Although in Figure 5 it is set to include the highest point P of the porous portion 3b, the highest point Q1 of the central region AR1, and the highest point Q2 of the outer peripheral region AR2, these highest points may not coexist in a cross section along the length direction L and the thickness direction T, and may not coexist in a cross section along the width direction W and the thickness direction T either.

[0103] The position of the highest point P of the porous portion 3b when viewed from the thickness direction T is not particularly limited. For example, when viewed from the thickness direction T, the highest point P of the porous portion 3b may be located at the center of the porous portion 3b, or may be located at a portion away from the center of the porous portion 3b toward the outer edge side. That is, the porous portion 3b may be highest at the center, or may be highest at a portion away from the center toward the outer edge side.

[0104] The position of the highest point Q1 of the central region AR1 when observed from the thickness direction T is not particularly limited. For example, when observed from the thickness direction T, the highest point Q1 of the central region AR1 may be located at the center of the central region AR1, that is, at the center of the solid electrolyte layer 7a, or may be located at a portion away from the center of the central region AR1 toward the peripheral region AR2 side. That is, the central region AR1 may be highest at the center or may be highest at a portion away from the center toward the peripheral region AR2 side.

[0105] Although it is set as the Figure 5 point existing at the highest position in the central region AR1 when observing the cross-section shown is the highest point Q1 in the entire central region AR1, it may not be the highest point Q1. That is, the point existing at the highest position in the central region AR1 when observing other cross-sections along the thickness direction T may also be the highest point Q1.

[0106] In the entire central region AR1, there may be only one highest point Q1 of the central region AR1, or there may be multiple highest points Q1. In addition, according to the cross-section along the thickness direction T, the highest point Q1 of the central region AR1 may not exist, may exist only at one point, or may Figure 5 exist at multiple points as shown. In Figure 5 it is shown that the height of the central region AR1 is fixed as if there are multiple highest points Q1 in the central region AR1.

[0107] The height of the point existing at the highest position in the central region AR1 when observing the cross-section along the thickness direction T may vary or may not vary according to the cross-section along the thickness direction T.

[0108] The position of the highest point Q2 of the peripheral region AR2 when observed from the thickness direction T is not particularly limited. For example, when observed from the thickness direction T, the highest point Q2 of the peripheral region AR2 may be located at the end portion of the peripheral region AR2 on the side opposite to the central region AR1, that is, at the outer edge of the solid electrolyte layer 7a, or may be located at a portion of the peripheral region AR2 away from the end portion on the side opposite to the central region AR1 toward the central region AR1 side. That is, the peripheral region AR2 may be highest at the end portion on the side opposite to the central region AR1 or may be highest at a portion away from the end portion on the side opposite to the central region AR1 toward the central region AR1 side.

[0109] Although it is set as when observing Figure 5When observing the cross-section shown, the point at the highest position in the outer peripheral region AR2 is the highest point Q2 in the entire outer peripheral region AR2, but it may not be the highest point Q2. That is to say, when observing other cross-sections along the thickness direction T, the point at the highest position in the outer peripheral region AR2 may also be the highest point Q2.

[0110] The highest point Q2 of the outer peripheral region AR2 may have only one point or multiple points in the entire outer peripheral region AR2. In addition, according to the cross-section along the thickness direction T, the highest point Q2 of the outer peripheral region AR2 may not exist, may have only one point, or may have multiple points as Figure 5 shown. In Figure 5 , it is shown that the height of the outer peripheral region AR2 becomes the highest at both end portions on the side opposite to the central region AR1, and there are two highest points Q2 in the outer peripheral region AR2.

[0111] The height of the point at the highest position in the outer peripheral region AR2 when observing the cross-section along the thickness direction T may change or may not change according to the cross-section along the thickness direction T.

[0112] Although in Figure 5 , it shows the observation of the cross-section along the length direction L and the thickness direction T, but when observing other cross-sections along the thickness direction T, for example, the cross-section along the width direction W and the thickness direction T, similarly, the outer peripheral region AR2 is higher than the central region AR1. In this way, when observing the cross-section along the thickness direction T, the outer peripheral region AR2 is higher than the central region AR1, so it can be said that the outer peripheral region AR2 is higher than the central region AR1 around the central region AR1.

[0113] Regarding the case where the outer peripheral region AR2 is higher than the central region AR1 around the central region AR1, for example, it can be known from the contour line image taken by a confocal microscope. In addition, the cross-section along the thickness direction T as exemplified in Figure 5 is observed as a cross-section image taken by, for example, a scanning electron microscope (SEM). By combining the analysis of the contour line image and the cross-section image as described above, the position of the highest point P of the porous portion 3b can be known, that is, the position of the reference plane S, the position of the highest point Q1 of the central region AR1, and the position of the highest point Q2 of the outer peripheral region AR2 can be known.

[0114] The solid electrolytic capacitor of Embodiment 1 of the present invention, that is, Figure 1 , Figure 2 etc. The solid electrolytic capacitor 1 shown is manufactured, for example, by the following method.

[0115] <Resin molded body forming process>

[0116] First, prepare a valve-acting metal substrate 3a having a porous portion 3b on its surface, that is, the anode 3. Then, an anodizing treatment is performed on the surface of the porous portion 3b, whereby a dielectric layer 5 is formed on the surface of the porous portion 3b.

[0117] Next, a solid electrolyte layer 7a is preferably formed on the surface of the dielectric layer 5 by a screen printing method. At this time, on the surface of the dielectric layer 5, the solid electrolyte layer 7a is formed such that the outer peripheral region AR2 is higher than the central region AR1 around the central region AR1.

[0118] A solid electrolyte layer 7a having such a shape can be formed, for example, by making the number of coating times during screen printing on the surface of the dielectric layer 5 larger in the region corresponding to the outer peripheral region AR2 than in the region corresponding to the central region AR1, or by adjusting the specifications of the screen printing plate, or by adjusting the coating conditions during screen printing.

[0119] When the number of coating times during screen printing on the surface of the dielectric layer 5 is larger in the region corresponding to the outer peripheral region AR2 than in the region corresponding to the central region AR1, for example, the number of coating times in the region corresponding to the central region AR1 can be set to one, and the number of coating times in the region corresponding to the outer peripheral region AR2 can be set to two. However, from the viewpoints of manufacturing efficiency and cost, it is preferable that the coating in the region corresponding to the central region AR1 and the coating in the region corresponding to the outer peripheral region AR2 are performed simultaneously at one time. In this case, when forming the solid electrolyte layer 7a, it is preferable to adjust the specifications of the screen printing plate or the coating conditions during screen printing as follows.

[0120] When adjusting the specifications of the screen printing plate, for example, the following methods are effective: making the wire diameter of the screen printing plate smaller in the region corresponding to the outer peripheral region AR2 than in the region corresponding to the central region AR1, or making the mesh of the screen printing plate larger in the region corresponding to the outer peripheral region AR2 than in the region corresponding to the central region AR1.

[0121] When adjusting the coating conditions during screen printing, for example, the following methods are effective: making the printing pressure during screen printing higher in the region corresponding to the outer peripheral region AR2 than in the region corresponding to the central region AR1, or making the printing speed during screen printing slower in the region corresponding to the outer peripheral region AR2 than in the region corresponding to the central region AR1.

[0122] Next, a conductive layer 7b is formed on the surface of the solid electrolyte layer 7a by a screen printing method or the like.

[0123] Next, a cathode lead-out layer 7c is formed on the surface of the conductive layer 7b by a method of laminating metal foils, screen printing, or the like. When forming the cathode lead-out layer 7c, it is preferable to bond to the dielectric layer 5 via an insulating adhesive layer 10.

[0124] In this way, a cathode 7 having a solid electrolyte layer 7a, a conductive layer 7b, and a cathode lead-out layer 7c is formed.

[0125] Through the above, a capacitor element 20 having an anode 3, a dielectric layer 5 provided on the surface of the anode 3, and a cathode 7 facing the anode 3 with the dielectric layer 5 interposed therebetween is manufactured.

[0126] Next, a plurality of capacitor elements 20 are laminated to manufacture a laminate 30. Then, the periphery of the laminate 30 is sealed with a sealing resin 8 by compression molding or the like to form a resin molded body 9.

[0127] The resin molded body 9 has a substantially rectangular parallelepiped shape and has a first end face 9a and a second end face 9b facing each other in the length direction L, a first main face 9c and a second main face 9d facing each other in the thickness direction T, and a first side face 9e and a second side face 9f facing each other in the width direction W.

[0128] In the resin molded body 9, the anode 3 is exposed from the first end face 9a, and the cathode 7 (here, the cathode lead-out layer 7c) is exposed from the second end face 9b.

[0129] <First external electrode forming step>

[0130] A first external electrode 11 connected to the anode 3 exposed from the first end face 9a is formed on the first end face 9a of the resin molded body 9. At this time, the first external electrode 11 can also be formed to extend from the first end face 9a of the resin molded body 9 to a part of each of at least one of the first main face 9c, the second main face 9d, the first side face 9e, and the second side face 9f.

[0131] <Second external electrode forming step>

[0132] A second external electrode 13 connected to the cathode 7 (here, the cathode lead-out layer 7c) exposed from the second end face 9b is formed on the second end face 9b of the resin molded body 9. At this time, the second external electrode 13 can also be formed to extend from the second end face 9b of the resin molded body 9 to a part of each of at least one of the first main face 9c, the second main face 9d, the first side face 9e, and the second side face 9f.

[0133] The first external electrode forming step and the second external electrode forming step can be performed at different timings or at the same timing. When the two steps are performed at different timings, their order is not particularly limited.

[0134] Through the above, the solid electrolytic capacitor 1 shown in Figure 1 , Figure 2 etc. is manufactured.

[0135] [Modification Example of Embodiment 1]

[0136] Although in the solid electrolytic capacitor of Embodiment 1 of the present invention, that is, in the solid electrolytic capacitor 1 shown in Figure 1 , Figure 2 etc., the cathode lead-out layer 7c is joined to the dielectric layer 5 via the insulating adhesive layer 10, the insulating adhesive layer 10 may not be provided.

[0137] Figure 6 It is a cross-sectional schematic view showing a solid electrolytic capacitor according to a modification example of Embodiment 1 of the present invention.

[0138] As shown in Figure 6 , in the solid electrolytic capacitor 1a, the insulating adhesive layer 10 is not provided. More specifically, the insulating adhesive layer 10 does not intervene between the dielectric layer 5 and the cathode lead-out layer 7c.

[0139] [Embodiment 2]

[0140] In the solid electrolytic capacitor of the present invention, the above solid electrolyte layer may also have a plurality of protrusions on the surface in the above central region, and the vertices of the plurality of protrusions may also be lower than the above outer peripheral region. Hereinafter, an example of such a solid electrolytic capacitor of the present invention will be described as the solid electrolytic capacitor of Embodiment 2 of the present invention. The solid electrolytic capacitor of Embodiment 2 of the present invention is the same as the solid electrolytic capacitor of Embodiment 1 of the present invention except for the form of the solid electrolyte layer.

[0141] Figure 7 It is a cross-sectional schematic view showing a part of the resin molded body in the solid electrolytic capacitor of Embodiment 2 of the present invention. In addition, in the cross-section along the length direction L and the thickness direction T shown in Figure 7 , similar to Figure 5 , for the sake of convenience of explanation, it is assumed to include the highest point in the entire porous portion 3b, the highest point in the entire central region AR1, and the highest point in the entire outer peripheral region AR2.

[0142] As shown in Figure 7 , in the resin molded body 109, a part of the solid electrolyte layer 7a protrudes. Thus, the solid electrolyte layer 7a has a plurality of protrusions 50 on the surface in the central region AR1.

[0143] The vertices Q3 of the plurality of protrusions 50 are lower than the outer peripheral region AR2. More specifically, the vertices Q3 of the plurality of protrusions 50 are lower than the highest point Q2 of the outer peripheral region AR2.

[0144] On the other hand, the outer peripheral region AR2 is higher than the central region AR1 around the central region AR1. Therefore, it can also be said that the outer peripheral region AR2 is higher than the apexes Q3 of the plurality of protrusions 50 around the central region AR1. More specifically, the highest point Q2 of the outer peripheral region AR2 is higher than the apexes Q3 of the plurality of protrusions 50.

[0145] The apexes Q3 of the plurality of protrusions 50 refer to the maximum points on the surface of the solid electrolyte layer 7a when observing the cross-section along the thickness direction T. Thus, the apex that exists at the highest position among the apexes Q3 of the plurality of protrusions 50 is still the highest point Q1 of the central region AR1. For example, in Figure 7 it is shown that the heights of the apexes Q3 of the plurality of protrusions 50 are the same, and each apex Q3 also becomes the highest point Q1 of the central region AR1.

[0146] In a conventional solid electrolytic capacitor, when the solid electrolytic capacitor is in a high-temperature state, for example, when the solid electrolytic capacitor is mounted on a wiring board via solder and heat-treated in a reflow soldering furnace, sometimes the solid electrolyte layer opens, and thus the base such as the dielectric layer and the porous portion is exposed from the solid electrolyte layer. In this case, if pressure is applied to the cathode lead-out layer from the outside, or the inside of the solid electrolytic capacitor expands, the anode and the cathode lead-out layer become close to each other, so there is a concern of short-circuit between the anode and the cathode lead-out layer. In contrast, in the solid electrolytic capacitor of the present invention, the outer peripheral region AR2 of the solid electrolyte layer 7a is higher than the central region AR1 around the central region AR1, so the anode 3 and the cathode lead-out layer 7c are less likely to approach each other. In addition, in the solid electrolytic capacitor of Embodiment 2 of the present invention, the interval between the anode 3 and the cathode lead-out layer 7c can be ensured by the plurality of protrusions 50 provided in the solid electrolyte layer 7a, so the anode 3 and the cathode lead-out layer 7c are even less likely to approach each other. Therefore, in the solid electrolytic capacitor of Embodiment 2 of the present invention, even in a high-temperature state, short-circuit between the anode 3 and the cathode lead-out layer 7c can be prevented, and the reliability is also improved.

[0147] From the viewpoint of ensuring the interval between the anode 3 and the cathode lead-out layer 7c, the interval R between the apexes Q3 of the plurality of protrusions 50 is preferably 170 μm or less, and further preferably 50 μm or more. In this case, when observing the cross-section along the length direction L and the thickness direction T as shown in Figure 7 needless to say, even when observing other cross-sections along the thickness direction T, for example, the cross-section along the width direction W and the thickness direction T, the interval R between the apexes Q3 of the plurality of protrusions 50 is preferably 170 μm or less, and further preferably 50 μm or more.

[0148] The interval R between the apexes Q3 of the plurality of protrusions 50 is defined as follows.

[0149] When observing a cross-section along the thickness direction T, in the case where there are more than 5 vertices Q3, the average value of the intervals between adjacent vertices Q3 is calculated for the 5 vertices Q3 selected in the order of higher position among them. On the other hand, when observing a cross-section along the thickness direction T, in the case where there are not more than 5 vertices Q3, the average value of the intervals between adjacent vertices Q3 is calculated for all the vertices Q3. Then, the average value thus obtained is defined as the interval R between the vertices Q3 of the plurality of protrusions 50.

[0150] From the viewpoint of ensuring the interval between the anode 3 and the cathode lead-out layer 7c, the height H3 of the vertices Q3 of the plurality of protrusions 50 is preferably 2 μm or more, and further preferably 3 μm or less. In this case, Figure 7 Needless to say, when observing the cross-section shown along the length direction L and the thickness direction T, and also when observing other cross-sections along the thickness direction T, for example, the cross-section along the width direction W and the thickness direction T, the height H3 of the vertices Q3 of the plurality of protrusions 50 is preferably 2 μm or more, and further preferably 3 μm or less.

[0151] The height H3 of the vertices Q3 of the plurality of protrusions 50 is defined as follows.

[0152] When observing a cross-section along the thickness direction T, in the case where there are more than 5 vertices Q3, the average value of the heights of the vertices Q3 is calculated for the 5 vertices Q3 selected in the order of higher position among them. On the other hand, when observing a cross-section along the thickness direction T, in the case where there are not more than 5 vertices Q3, the average value of the heights of the vertices Q3 is calculated for all the vertices Q3. Then, the average value thus obtained is defined as the height H3 of the vertices Q3 of the plurality of protrusions 50.

[0153] In the case where the interval R between the vertices Q3 of the plurality of protrusions 50 is greater than 170 μm, if the height H3 of the vertices Q3 of the plurality of protrusions 50 is less than 2 μm, the interval between the anode 3 and the cathode lead-out layer 7c cannot be sufficiently ensured, and there is a concern of short-circuit between the anode 3 and the cathode lead-out layer 7c in a high-temperature state. From the viewpoint of preventing such a short-circuit between the anode 3 and the cathode lead-out layer 7c, in the case where the interval R between the vertices Q3 of the plurality of protrusions 50 is greater than 170 μm, the height H3 of the vertices Q3 of the plurality of protrusions 50 is preferably 3 μm or more.

[0154] In the case where the interval R between the vertices Q3 of the plurality of protrusions 50 is less than 70 μm, the height H3 of the vertices Q3 of the plurality of protrusions 50 may also be 2 μm or less.

[0155] When observing a cross-section along the thickness direction T, among the plurality of protrusions 50, the interval between adjacent vertices Q3 can be asFigure 7 They may be the same as each other or different from each other as shown.

[0156] When observing a cross-section along the thickness direction T, the heights of the vertices Q3 of the plurality of protrusions 50 may be the same as each other or different from each other as shown. Figure 7 They may be the same as each other or different from each other as shown. Figure 7 In, it is shown that the heights of the vertices Q3 of the plurality of protrusions 50 are the same as each other. Since each vertex Q3 also becomes the highest point Q1 of the central region AR1, the height H3 of the vertices Q3 of the plurality of protrusions 50 becomes the same as the height H1 of the highest point Q1 of the central region AR1.

[0157] As the shape of the plurality of protrusions 50, there is no particular limitation. For example, a conical shape, a pyramidal shape, etc. can be cited. In this way, when observing a cross-section along the thickness direction T, the plurality of protrusions 50 may be a so-called tapered shape in which the length in the direction orthogonal to the thickness direction T decreases from the side of the dielectric layer 5 toward the side of the cathode lead-out layer 7c, but may not be a tapered shape.

[0158] The tips of the plurality of protrusions 50 may be sharp, may have rounded corners, or may be flat.

[0159] The shapes of the plurality of protrusions 50 may be the same as each other or different from each other.

[0160] In the solid electrolyte layer 7a, in addition to existing in the central region AR1, the plurality of protrusions 50 may also exist in regions other than the central region AR1. For example, in addition to existing in the central region AR1, the plurality of protrusions 50 may also exist in the region between the central region AR1 and the outer peripheral region AR2, may also exist in the outer peripheral region AR2, and may also exist in the region between the central region AR1 and the outer peripheral region AR2 and the outer peripheral region AR2.

[0161] The manufacturing method of the solid electrolytic capacitor according to Embodiment 2 of the present invention is the same as the manufacturing method of the solid electrolytic capacitor according to Embodiment 1 of the present invention, except that when forming the resin molded body 109 in the resin molding step, the solid electrolyte layer 7a is formed to have a plurality of protrusions 50 on the surface in the central region AR1.

[0162] As described above, the solid electrolyte layer 7a is preferably formed on the surface of the dielectric layer 5 by a screen printing method. At this time, so-called mesh marks due to the mesh shape of the screen printing plate appear on the surface of the central region AR1 of the solid electrolyte layer 7a. Thereby, a plurality of protrusions 50 can be formed on the surface of the central region AR1 of the solid electrolyte layer 7a.

[0163] When forming the solid electrolyte layer 7a by the screen printing method, various parameters of the plurality of protrusions 50, such as the interval R between the vertices Q3 of the plurality of protrusions 50 and the height H3 of the vertices Q3 of the plurality of protrusions 50, can be controlled by adjusting the wire diameter, mesh holes, etc. of the screen printing plate.

[0164] Description of Reference Numerals

[0165] 1, 1a: Solid electrolytic capacitor;

[0166] 3: Anode;

[0167] 3a: Valve-acting metal substrate;

[0168] 3b: Porous portion;

[0169] 5: Dielectric layer;

[0170] 7: Cathode;

[0171] 7a: Solid electrolyte layer;

[0172] 7b: Conductive layer;

[0173] 7c: Cathode lead-out layer;

[0174] 8: Sealing resin;

[0175] 9, 109: Resin molded body;

[0176] 9a: First end face;

[0177] 9b: Second end face;

[0178] 9c: First main face;

[0179] 9d: Second main face;

[0180] 9e: First side face;

[0181] 9f: Second side face;

[0182] 10: Insulating adhesive layer;

[0183] 11: First external electrode;

[0184] 13: Second external electrode;

[0185] 20: Capacitor element;

[0186] 30: Laminate;

[0187] 50: Protrusion;

[0188] AR1: Central region;

[0189] AR2: Peripheral region;

[0190] E1: The first outer edge;

[0191] E2: The second outer edge;

[0192] E3: The third outer edge;

[0193] E4: The fourth outer edge;

[0194] H1: The height of the highest point in the central region;

[0195] H2: The height of the highest point in the peripheral region;

[0196] H3: The height of the vertex of the protrusion;

[0197] L: The length direction;

[0198] M1: The length in the length direction of the central region;

[0199] M2: The length in the width direction of the central region;

[0200] M3: The length in the length direction of the peripheral region;

[0201] M4: The length in the width direction of the peripheral region;

[0202] N1: The distance in the length direction between the first outer edge and the second outer edge;

[0203] N2: The distance in the width direction between the third outer edge and the fourth outer edge;

[0204] P: The highest point of the porous part;

[0205] Q1: The highest point in the central region;

[0206] Q2: The highest point in the peripheral region;

[0207] Q3: The vertex of the protrusion;

[0208] R: The interval between the vertices of the protrusions;

[0209] S: The reference plane;

[0210] T: The thickness direction;

[0211] U: The space;

[0212] W: The width direction.

Claims

1. A solid electrolytic capacitor, characterized in that: In the thickness direction, it has: A valve-acting metal substrate having a porous portion on its surface; A dielectric layer provided on the surface of the porous portion; A solid electrolyte layer provided on the surface of the dielectric layer; A conductive layer provided on the surface of the solid electrolyte layer; and A cathode lead-out layer provided on the surface of the conductive layer, When viewed from the thickness direction, the solid electrolyte layer has: A central region including the center of the solid electrolyte layer; and An outer peripheral region located around the central region and including all of the outer edge of the solid electrolyte layer, When defining the height in the thickness direction with respect to a reference plane that includes the highest point of the porous portion in the thickness direction and is orthogonal to the thickness direction, the outer peripheral region is higher than the central region throughout the periphery of the central region, The conductive layer is provided on at least the central region of the solid electrolyte layer, The entire conductive layer exists within the outer edge of the solid electrolyte layer.

2. The solid electrolytic capacitor according to claim 1, characterized in that: The height of the highest point of the outer peripheral region is greater than the height of the highest point of the central region by 2 μm or more.

3. The solid electrolytic capacitor according to claim 1 or 2, characterized in that: The solid electrolyte layer has a plurality of protrusions on its surface in the central region, The vertices of the plurality of protrusions are lower than the outer peripheral region.

4. The solid electrolytic capacitor according to claim 3, characterized in that: The interval between the vertices of the plurality of protrusions is 170 μm or less.

5. The solid electrolytic capacitor according to claim 4, characterized in that: The height of the vertices of the plurality of protrusions is 2 μm or more.

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