Solid electrolytic capacitor and method for manufacturing same

Abstract

The present invention is provided with: a valve metal foil (10) which has a porous part (12) and a core part (11) that is continuous with the porous part (12), and in which a dielectric layer (20) is formed on at least a part of the surface of the porous part (12); a solid electrolyte layer (30) covering at least a part of the surface of the dielectric layer (20); a current collector layer (40) covering at least a part of the solid electrolyte layer (30); a first through electrode (61) electrically connected to the current collector layer (40); and a first insulating layer (71) provided between the first through electrode (61) and the valve metal foil (10). In the porous part (12), a first opening hole (H1) is provided in a portion where the first through electrode (61) is formed, and the dielectric layer (20) at least partially covered with the solid electrolyte layer (30) is provided on a first inner peripheral surface of the first opening hole (H1).

Description

Solid electrolytic capacitor and method for manufacturing the same Cross-Reference to Related Applications

[0001] The present disclosure claims the benefit of priority based on Japanese Patent Application No. 2025-056648 filed with the Japan Patent Office on March 28, 2025, the entire content of which is incorporated herein by reference. All documents cited in the present disclosure are specifically incorporated in their entirety herein by reference.

[0002] The present disclosure relates to a solid electrolytic capacitor and a method for manufacturing the same.

[0003] Patent Document 1 proposes a solid electrolytic capacitor described as follows: "A solid electrolytic capacitor, wherein in a part of a valve metal foil having a porous portion with a dielectric film formed at least on a surface thereof, a first through hole is formed in a part of the valve metal foil, a first insulating layer is formed on an inner wall of the first through hole, an anode-cathode separation portion formed of a second insulating layer is provided, and a valve metal foil serving as an anode portion and a current collector layer serving as a cathode portion are electrically insulated from each other, the solid electrolytic capacitor comprising: at least one or more floating island-shaped third insulating layers formed on a part of the dielectric film; a solid electrolyte layer formed on the dielectric film at an outer portion of the third insulating layer; and a current collector layer formed on an upper surface of the solid electrolyte layer, wherein a second through hole penetrating through the third insulating layer, the dielectric film below the third insulating layer, and the anode is provided in a part of the third insulating layer where the first insulating layer is not formed, a third through hole penetrating through the first insulating layer is provided in the first through hole where the first insulating layer is formed, and a through wiring is formed in at least one or more of the floating island-shaped third insulating layer portions by providing a through-hole electrode in the second through hole and the third through hole."

[0004] Japanese Unexamined Patent Publication No. 2009-4417

[0005] In Patent Document 1, the through-hole electrode that serves as the anode of a capacitor element is separated from the solid electrolyte layer that serves as the cathode and insulated by a dielectric layer and an insulating layer. The insulating layer was formed by filling the surface of the portion of the dielectric layer of the valve metal foil that serves as the anode, where the solid electrolyte layer is not formed, with an insulating material such as resin. When attempting to form an insulating layer in this way, the insulating material such as resin tends to spread due to capillary action as it penetrates into the porous portion, making it difficult to form a fine pattern.

[0006] One aspect of the present disclosure relates to a solid electrolytic capacitor. The solid electrolytic capacitor comprises a valve metal foil having a first main surface and a second main surface opposite to the first main surface, and having a porous portion formed at least on the side of the first main surface and a core portion continuous with the porous portion, with a dielectric layer formed on at least a part of the surface of the porous portion; a solid electrolyte layer covering at least a part of the surface of the dielectric layer; a current collector layer covering at least a part of the solid electrolyte layer; a first through electrode penetrating the valve metal foil in the thickness direction and electrically connected to the current collector layer; and a first insulating layer provided between the first through electrode and the valve metal foil. The porous portion is provided with a first opening hole in the portion forming the first through electrode. The dielectric layer, which is at least a part of the solid electrolyte layer, is provided on the first inner circumferential surface of the first opening hole.

[0007] Another aspect of the present disclosure relates to a method for manufacturing a solid electrolytic capacitor. The manufacturing method includes the steps of: preparing a valve metal foil having a first main surface and a second main surface opposite to the first main surface, and having a porous portion formed at least on the side of the first main surface and a core portion continuous with the porous portion, and having a first opening hole for forming a first through electrode; forming a dielectric layer on at least a part of the surface of the porous portion of the valve metal foil; providing a solid electrolyte layer covering at least a part of the surface of the dielectric layer; providing a current collector layer covering at least a part of the solid electrolyte layer; filling the first opening hole with a first insulating layer; providing a first through electrode penetrating the first insulating layer and the valve metal foil in the thickness direction; and electrically connecting the first through electrode and the current collector layer. The dielectric layer, which is at least a part of which is covered by the solid electrolyte layer, is provided on the first inner circumferential surface of the first opening hole.

[0008] According to the solid electrolytic capacitor and its manufacturing method described herein, the solid electrolyte layer can be patterned with high precision, thereby securing a larger area for functioning as a capacitor and enabling an increase in capacitance.

[0009] This is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100 according to the first embodiment of this disclosure. This is a transverse cross-sectional view showing the configuration of a solid electrolytic capacitor 100. This is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100A according to a first modification of the first embodiment of this disclosure. This is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100B according to a second modification of the first embodiment of this disclosure. This is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100C according to a third modification of the first embodiment of this disclosure. This is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100D according to a fourth modification of the first embodiment of this disclosure. This is an explanatory diagram showing the first step in the manufacturing method of a solid electrolytic capacitor according to the second embodiment of this disclosure. This is an explanatory diagram showing the second step in the manufacturing method of a solid electrolytic capacitor. This is an explanatory diagram showing the third step in the manufacturing method of a solid electrolytic capacitor. This is an explanatory diagram showing the fourth step in the manufacturing method of a solid electrolytic capacitor. This is an explanatory diagram showing the fifth step in the manufacturing method of a solid electrolytic capacitor. This is an explanatory diagram showing the sixth step in the manufacturing method of a solid electrolytic capacitor. This is an explanatory diagram showing the seventh step in the manufacturing method of a solid electrolytic capacitor. This is an explanatory diagram showing the eighth step in the manufacturing method of a solid electrolytic capacitor.

[0010] Novel features of the present invention are described in the appended claims, but the present invention, both in terms of structure and content, and 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.

[0011] The solid electrolytic capacitor and its manufacturing method related to this disclosure are described below with examples. However, 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 ​​and materials may be applied as long as the effects of this disclosure are achieved.

[0012] 1. Solid electrolytic capacitor The solid electrolytic capacitor according to this disclosure comprises a valve metal foil, a solid electrolyte layer, a current collector layer, a first through electrode, and a first insulating layer.

[0013] 1.1 Valve Metal Foil The valve metal foil has a first main surface and a second main surface opposite to the first main surface. The valve metal foil has a porous portion formed at least on the side of the first main surface and a core portion continuous with the porous portion. A dielectric layer is formed on at least a portion of the surface of the porous portion.

[0014] Valve metal refers to a metal whose surface is covered with a film of metal oxide due to oxidation, thereby exhibiting corrosion resistance, and whose oxide film also has a flow-rectifying effect. Examples of valve metals include, but are not limited to, aluminum (Al), tantalum (Ta), and niobium (Nb). Valve metal foil may be foil made of valve metal, or foil containing an alloy or compound containing valve metal.

[0015] The porous portion is formed on at least the first main surface side of the valve metal foil. In other words, the porous portion is formed only on the first main surface side of the valve metal foil, or on both the first and second main surfaces. However, even when the porous portion is formed on the first main surface side, for example, the porous portion does not necessarily cover the entire first main surface, and areas not covered by the porous portion may remain on the first main surface. Note that the first and second main surfaces are names defined for convenience.

[0016] Examples of porous parts include sintered bodies of metal particles fixed to the core. Alternatively, the valve metal foil may be an etched foil, and the porous part may be a roughened portion of the etched foil. However, the porous part is not limited to these examples.

[0017] The dielectric layer is composed of, for example, a metal oxide. Methods for forming a layer containing a metal oxide on the surface of a porous part include, but are not limited to, immersion in a chemical solution to oxidize the surface of the porous part, heating in an oxygen-containing atmosphere, anodic oxidation, and atomic layer deposition (ALD) method. However, the dielectric layer is not limited to a layer containing a metal oxide; it only needs to have insulating properties.

[0018] 1.2 Solid Electrolyte Layer The solid electrolyte layer covers at least a portion of the surface of the dielectric layer. For example, manganese compounds and conductive polymers can be used for the solid electrolyte layer. Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyparaphenylenevinylene, polyacene, polythiophenevinylene, polyfluorene, polyvinylcarbazole, polyvinylphenol, polypyridine, or derivatives of these polymers. These may be used individually or in combination. The conductive polymer may also be a copolymer of two or more monomers. Among these, polythiophene, polyaniline, and polypyrrole are preferred in terms of their excellent conductivity. Polythiophene is particularly preferred in terms of its excellent heat resistance.

[0019] The solid electrolyte layer containing the conductive polymer described above is formed, for example, by polymerizing raw material monomers on a dielectric layer. Alternatively, it is formed by coating a dielectric layer with a liquid containing the conductive polymer described above. The solid electrolyte layer consists of one or more solid electrolyte layers. When the solid electrolyte layer consists of two or more layers, the composition of the conductive polymer used in each layer and the method of formation (polymerization method) may differ.

[0020] One method for polymerizing the solid electrolyte layer containing the conductive polymer on a dielectric layer is to support an oxidizing agent capable of oxidizing raw material monomers on the porous portion of the valve metal foil by dropping and drying a solution containing the oxidizing agent, and then exposing the valve metal foil to the vapor of the raw material monomers. Alternatively, the conductive polymer may be grown by immersion in a solution containing monomers. Another method involves forming a pre-coat layer of conductive material by applying a dispersion of conductive material to the porous portion of the valve metal foil in advance, and then forming a conductive polymer layer by an electrolytic polymerization reaction using the pre-coat layer as a seed layer by applying a voltage to the pre-coat layer while immersing it in a solution containing the monomers of the conductive polymer. Alternatively, a method of combining these methods to create a multilayer structure is also conceivable.

[0021] 1.3 Current Collector Layer The current collector layer covers at least a portion of the solid electrolyte layer. The current collector layer includes, for example, a carbon layer formed to cover the solid electrolyte layer and a metal paste layer formed on the surface of the carbon layer. The carbon layer includes a conductive carbon material such as graphite and a resin. The metal paste layer includes, for example, metal particles (e.g., silver) and a resin. However, the composition of the current collector layer is not limited to these examples.

[0022] 1.4 First Through Electrode The first through electrode penetrates the valve metal foil in the thickness direction and is electrically connected to the current collector layer. The first insulating layer is provided between the first through electrode and the valve metal foil.

[0023] The porous portion is provided with a first opening hole in the area where the first through electrode is formed. The first inner circumferential surface of the first opening hole is provided with a dielectric layer, at least partially covered by a solid electrolyte layer. In other words, on the valve metal foil, a first opening hole is provided in the area where the first through electrode is formed, where there is no porous portion, and a solid electrolyte layer is formed to cover the first inner circumferential surface (on which the dielectric layer is formed).

[0024] With this configuration, the solid electrolyte layer can be patterned in a shape that is roughly the same as the shape of the porous portion by methods such as supporting the precursor solution of the solid electrolyte layer on the porous portion. As a result, the solid electrolyte layer can be patterned with high precision, which allows for a larger surface area to act as a capacitor, thus enabling an increase in capacitance.

[0025] 1.5 Regarding supplementary configurations, the solid electrolyte layer may be in contact with the first insulating layer on the first inner surface of the first opening.

[0026] At least a portion of the first opening has a bottom surface restricted by the core, and the dielectric layer may also be provided on the bottom surface.

[0027] When the first main surface is viewed from above, it is preferable that the pattern of the porous portion overlaps with 80% or more of the pattern of the solid electrolyte layer.

[0028] When the first main surface is viewed from above, it is preferable that the pattern of the current collector layer overlaps with the pattern of the solid electrolyte layer so that it does not extend beyond the pattern of the solid electrolyte layer.

[0029] 2. Modified Solid Electrolytic Capacitors The following describes some modified solid electrolytic capacitors with the configuration described above, highlighting their main differences.

[0030] The solid electrolytic capacitor may further include a second through-electrode that penetrates the valve metal foil in the thickness direction and is electrically connected to the valve metal foil, and a second insulating layer provided between the second through-electrode and the valve metal foil. In this case, the second through-electrode is no longer directly electrically connected to the valve metal foil, so the second through-electrode is electrically connected to the valve metal foil on the back surface of the valve metal foil.

[0031] Alternatively, the valve may further include a sealing portion that seals the valve metal foil, solid electrolyte layer, and current collector layer, and the first insulating layer may be formed integrally with the sealing portion. With such a configuration, it is not necessary to provide a first insulating layer (and further a second insulating layer) separately from the sealing portion, thus simplifying the structure and manufacturing process.

[0032] Alternatively, porous sections may be provided on the first main surface side and the second main surface side, respectively. With such a configuration, although the overall thickness may be somewhat larger, a greater capacitance per unit area in plan view can be achieved.

[0033] Alternatively, the first insulating layer may be part of the dielectric layer. With such a configuration, the volume of the first insulating layer can be reduced, and the cross-sectional area of ​​the first through-electrode can be increased, thereby reducing the series resistance of the first through-electrode.

[0034] 3. Method for Manufacturing Solid Electrolytic Capacitors The method for manufacturing solid electrolytic capacitors comprises the following steps.

[0035] 3.1 Process for preparing the valve metal foil In this process, a valve metal foil is prepared having a first main surface and a second main surface opposite to the first main surface, and having a porous portion formed at least on the side of the first main surface and a core portion continuous with the porous portion, and having a first opening hole formed for forming a first through electrode.

[0036] 3.2 Process for forming a dielectric layer In this process, a dielectric layer is formed on at least a portion of the surface of the porous portion of the valve metal foil.

[0037] 3.3 Process for Providing a Solid Electrolyte Layer In this process, a solid electrolyte layer is provided that covers at least a portion of the surface of the dielectric layer. At this time, a dielectric layer is provided on the first inner circumferential surface of the first opening hole, with at least a portion of it covered by the solid electrolyte layer.

[0038] 3.4 Process for Providing the Current Collector Layer In this process, a current collector layer is provided that covers at least a portion of the solid electrolyte layer. After this process, a sealed portion is formed by molding with a sealing material.

[0039] 3.5 Process of filling the first insulating layer In this process, the first insulating layer is filled into the first opening. More specifically, a through hole is formed at the position where the first through electrode is to be formed (first opening), and then filled with the first insulating layer.

[0040] 3.6 Process for Providing the First Through Electrode In this process, a first through electrode is provided that penetrates the first insulating layer and the valve metal foil in the thickness direction. More specifically, after forming the first through hole inside the through hole formed in "3.5 Process for Filling the First Insulating Layer", this first through hole is made into the first through electrode by copper plating or the like.

[0041] 3.7 Electrical Connection Process In this process, the first through electrode and the current collector layer are electrically connected.

[0042] This manufacturing method allows for highly precise patterning of the solid electrolyte layer, enabling the production of solid electrolytic capacitors with increased capacitance by securing a larger surface area for capacitor function.

[0043] 3.8 Modification of Manufacturing MethodA configuration further comprising a second through electrode may be adopted. In this case, in "3.1 Step of Preparing Valve Metal Foil", a valve metal foil in which a second opening for forming the second through electrode is formed may be prepared. Further, in "3.3 Step of Providing Solid Electrolyte Layer", the dielectric layer at least partially covered by the solid electrolyte layer may be provided on the second inner peripheral surface of the second opening. Furthermore, after "3.6 Step of Providing First Through Electrode", a step of providing the second through electrode may be further provided. In this step, the second through electrode penetrating the valve metal foil in the thickness direction is provided. More specifically, after forming a second through hole in a portion where the second through electrode is to be formed, the second through hole is formed into the second through electrode by copper plating treatment or the like. However, a core part of the valve metal foil may constitute a part of the second through electrode. Note that this step and the step shown in 3.6 may be performed in reverse order or simultaneously. Further, in "3.7 Step of Electrically Connecting", the first through electrode and the current collector layer may be electrically connected, and the second through electrode and the valve metal foil may be electrically connected.

[0044] 4 Specific Examples of Solid Electrolytic Capacitor and Manufacturing Method ThereofHereinafter, specific examples of the solid electrolytic capacitor and the manufacturing method thereof according to the present disclosure will be described with reference to the drawings. The components and steps described above can be applied to the constituent elements of the solid electrolytic capacitor and each step of the manufacturing method thereof described below, and can be modified based on the above description. Matters described below may be applied to the above embodiments. Among the constituent elements and steps of the solid electrolytic capacitor and the manufacturing method thereof in the specific examples described below, non-essential constituent elements and steps may be omitted. Note that the drawings shown below are schematic and do not accurately reflect the shape, number, etc. of actual members.

[0045] 4.1 Specific Example of Solid Electrolytic CapacitorFIG. 1 is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100 according to the first embodiment of the present disclosure. FIG. 2 is a transverse cross-sectional view showing the configuration of the solid electrolytic capacitor 100.

[0046] As shown in FIG. 1 and FIG. 2, the solid electrolytic capacitor 100 includes a valve metal foil 10, a solid electrolyte layer 30, a current collector layer 40, a sealing portion 50, a first through electrode 61, a second through electrode 62, a first insulating layer 71, an electrode wiring 80, and a terminal electrode 90.

[0047] The valve metal foil 10 has a first main surface 10a (front surface or upper surface) and a second main surface 10b (back surface or lower surface) opposite to the first main surface 10a. The valve metal foil 10 has a porous portion 12 formed at least on the first main surface 10a side, and a core portion 11 continuous with the porous portion 12. A dielectric layer 20 is formed on at least a part of the surface of the porous portion 12.

[0048] The solid electrolyte layer 30 covers at least a part of the surface of the dielectric layer 20. The current collector layer 40 covers at least a part of the solid electrolyte layer 30. The sealing portion 50 seals the valve metal foil 10, the solid electrolyte layer 30, the current collector layer 40 and the like.

[0049] The first through electrode 61 penetrates the valve metal foil 10 in the thickness direction, and is electrically connected to the current collector layer 40 via the electrode wiring 80 and the terminal electrode 90 disposed on the current collector layer 40. The second through electrode 62 penetrates the valve metal foil 10 in the thickness direction, and is electrically connected to the end face of the core portion 11 of the valve metal foil 10. The first insulating layer 71 is provided between the first through electrode 61 and the valve metal foil 10 (core portion 11).

[0050] In the porous portion 12, a first opening hole H1 is provided in a portion where the first through electrode 61 is formed, and a second opening hole H2 is provided in a portion where the second through electrode 62 is formed. The dielectric layer 20, at least a part of which is covered by the solid electrolyte layer 30, is respectively provided on the first inner peripheral surface of the first opening hole H1 and the second inner peripheral surface of the second opening hole H2.

[0051] According to such a configuration, since the solid electrolyte layer 30 can be patterned with high precision, a large area acting as a capacitor can be secured, and the capacitance can be increased.

[0052] 4.2 Other Specific Examples of Solid Electrolytic Capacitors Figure 3 is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100A according to a first modification of the first embodiment of the present disclosure. Figure 4 is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100B according to a second modification of the first embodiment of the present disclosure. Figure 5 is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100C according to a third modification of the first embodiment of the present disclosure. Figure 6 is a longitudinal cross-sectional view showing the configuration of a solid electrolytic capacitor 100D according to a fourth modification of the first embodiment of the present disclosure. Below, the features that differ from the solid electrolytic capacitor 100 described above will be mainly explained.

[0053] As shown in Figure 3, in the solid electrolytic capacitor 100A, a second insulating layer 72 is provided around the second through electrode 62, similar to how a first insulating layer 71 is provided around the first through electrode 61. In this case, the second through electrode 62 is not directly electrically connected to the valve metal foil 10. For example, the second through electrode 62 is electrically connected to the valve metal foil 10 on the back surface of the valve metal foil 10 via electrode wiring 80 and terminal electrode 90.

[0054] As shown in Figure 4, in the solid electrolytic capacitor 100B, the first insulating layer 71 and the second insulating layer 72 of the solid electrolytic capacitor 100 are integrated with the sealing portion 50. In other words, it is not necessary to provide the first insulating layer 71 and the second insulating layer 72 separately from the sealing portion 50, so the structure is simpler compared to the solid electrolytic capacitor 100.

[0055] As shown in Figure 5, in the solid electrolytic capacitor 100C, the porous portion 12, the solid electrolyte layer 30, and the current collector layer 40 are formed on both the first and second main surfaces of the valve metal foil 10. It is, so to speak, a double-sided element. Although the overall thickness may be somewhat larger, a larger capacitance can be achieved per unit area in a plan view.

[0056] As shown in Figure 6, the main differences between the solid electrolytic capacitor 100D and the solid electrolytic capacitor 100C are as follows: Specifically, the solid electrolytic capacitor 100D does not have a second through-electrode 62 that penetrates the valve metal foil 10 in the thickness direction and electrically connects to the end face of the core portion 11 of the valve metal foil 10. The first through-electrode 61 is formed to be integrated with the current collector layer 40. The first insulating layer 71 is part of the dielectric layer 20.

[0057] In addition, a second terminal electrode 92, which is electrically connected to the valve metal foil 10 and separate from the first terminal electrode 90 which is electrically connected to the current collector layer 40 via electrode wiring 80, may be provided so as to cover both ends of the solid electrolytic capacitor 100D.

[0058] 4.3 Specific Examples of Methods for Manufacturing Solid Electrolytic Capacitors Figures 7A to 7H are explanatory diagrams showing the first to eighth steps of the method for manufacturing a solid electrolytic capacitor according to the second embodiment of this disclosure. In this specific example, a second through electrode 62 is formed along with the first through electrode 61, but the second through electrode 62 may be omitted.

[0059] As shown in Figure 7A, in the first step, a porous portion 12 is formed with partial openings (for example, a first opening hole H1 and a second opening hole H2). Specifically, a paste of valve metal foil particles is screen printed onto the core portion 11 and sintered in a vacuum to form the porous portion. Alternatively, the openings are formed by partially removing and pressing the etched foil. Note that this first step is an example of "3.1 Step for preparing valve metal foil" in this disclosure.

[0060] Next, as shown in Figure 7B, in the second step, a voltage is applied in the electrolyte to perform anodizing treatment, thereby forming a dielectric layer 20 on the surface of the core portion 11 and the porous portion 12. This second step is an example of "3.2 Step for forming a dielectric layer" in this disclosure.

[0061] Next, as shown in Figure 7C, in the third step, a solid electrolyte layer 30 is formed to cover the porous portion 12. Specifically, a precursor solution of the oxidizing agent is applied so that it is supported on the porous portion 12, and this is dried to form the oxidizing agent only on the surface of the porous portion 12. Next, an oxidative polymerization reaction is induced by immersion in a precursor solution of the conductive polymer to form a solid electrolyte layer 30 made of the conductive polymer. Note that this third step is an example of "3.3 Step of providing a solid electrolyte layer" in this disclosure.

[0062] Next, as shown in Figure 7D, in the fourth step, the current collector layer 40 is formed by printing carbon liquid and silver paste in that order onto the surface of the solid electrolyte layer. This fourth step is an example of "3.4 Step for Providing the Current Collector Layer" in this disclosure.

[0063] Next, as shown in Figure 7E, in the fifth step, the sealed portion 50 is formed by molding with a sealing material (for example, a filler-containing epoxy resin).

[0064] Next, as shown in Figure 7F, in the sixth step, a first through-hole T1x is formed at the position where the first through-electrode 61 is to be formed, and this hole is filled with the first insulating layer 71. This sixth step is an example of "3.5 Step of filling the first insulating layer" of this disclosure.

[0065] Next, as shown in Figure 7G, in the seventh step, a first through-hole T1 is formed in the area where the first through-electrode 61 is to be formed (inside the first insulating layer 71). A second through-hole T2 is also formed in the area where the second through-electrode 62 is to be formed. Furthermore, via holes are formed to electrically connect with the current collector layer 40. The sealing portion 50 in the area of ​​the current collector layer 40 where the electrode wiring 80 is to be placed is removed to expose the current collector layer 40.

[0066] Next, as shown in Figure 7H, in the eighth step, the first through electrode 61 and the second through electrode 62 are formed by copper plating, the electrode wiring 80 is placed on the exposed current collector layer 40, and the terminal electrode 90 is formed. Note that the seventh and eighth steps are examples of "3.6 Step of providing the first through electrode," "3.7 Step of electrically connecting," and "3.8 Modification of the manufacturing method" of this disclosure.

[0067] This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its essence. Furthermore, various disclosures can be formed by appropriately combining the multiple components disclosed in the embodiments described above. For example, some components may be removed from all the components shown in the embodiments. The drawings schematically show each component for ease of understanding, and the number of each component shown may differ from the actual number due to the convenience of drawing creation. In addition, each component shown in the embodiments described above is an example and is not particularly limiting, and various modifications are possible without substantially departing from the effects of this disclosure.

[0068] 5. The following technologies are disclosed by the above descriptions of embodiments. (Technology 1) A solid electrolytic capacitor comprising: a valve metal foil having a first main surface and a second main surface opposite to the first main surface, and having a porous portion formed at least on the first main surface side and a core portion continuous with the porous portion, wherein a dielectric layer is formed on at least a part of the surface of the porous portion; a solid electrolyte layer covering at least a part of the surface of the dielectric layer; a current collector layer covering at least a part of the solid electrolyte layer; a first through electrode penetrating the valve metal foil in the thickness direction and electrically connected to the current collector layer; and a first insulating layer provided between the first through electrode and the valve metal foil, wherein the porous portion is provided with a first opening hole in the portion forming the first through electrode, and the dielectric layer, at least a part of which is covered with the solid electrolyte layer, is provided on the first inner circumferential surface of the first opening hole. (Technology 2) The solid electrolytic capacitor according to Technology 1, wherein the solid electrolyte layer is in contact with the first insulating layer on the first inner circumferential surface of the first opening hole. (Technology 3) A solid electrolytic capacitor according to Technology 1 or 2, wherein at least a portion of the first opening has a bottom surface restricted by the core, and the dielectric layer is also provided on the bottom surface. (Technology 4) A solid electrolytic capacitor according to any one of Technology 1 to 3, wherein the porous portion is a sintered body of metal particles fixed to the core. (Technology 5) A solid electrolytic capacitor according to any one of Technology 1 to 3, wherein the valve metal foil is an etched foil, and the porous portion is a roughened portion of the etched foil. (Technology 6) A solid electrolytic capacitor according to any one of Technology 1 to 5, wherein when the first main surface is viewed from above, the pattern of the porous portion overlaps with 80% or more of the pattern of the solid electrolyte layer. (Technology 7) A solid electrolytic capacitor according to Technology 6, wherein when the first main surface is viewed from above, the pattern of the current collector layer overlaps with the pattern of the solid electrolyte layer such that it does not extend beyond the pattern of the solid electrolyte layer.(Technology 8) A solid electrolytic capacitor according to any one of Techniques 1 to 7, further comprising a second through electrode that penetrates the valve metal foil in the thickness direction and is electrically connected to the valve metal foil, and a second insulating layer provided between the second through electrode and the valve metal foil, wherein the second through electrode is electrically connected to the valve metal foil on the second main surface. (Technology 9) A solid electrolytic capacitor according to any one of Techniques 1 to 8, further comprising a sealing portion that seals the valve metal foil, the solid electrolyte layer, and the current collector layer, wherein the first insulating layer is integrally formed with the sealing portion. (Technology 10) A solid electrolytic capacitor according to any one of Techniques 1 to 9, wherein the first insulating layer is a part of the dielectric layer. (Technology 11) A solid electrolytic capacitor according to any one of Techniques 1 to 10, wherein the porous portion is provided on the first main surface side and the second main surface side, respectively. (Technical 12) A method for manufacturing a solid electrolytic capacitor, comprising the steps of: preparing a valve metal foil having a first main surface and a second main surface opposite to the first main surface, and having a porous portion formed at least on the side of the first main surface and a core portion continuous with the porous portion, and having a first opening hole for forming a first through electrode; forming a dielectric layer on at least a part of the surface of the porous portion of the valve metal foil; providing a solid electrolyte layer covering at least a part of the surface of the dielectric layer; providing a current collector layer covering at least a part of the solid electrolyte layer; filling the first opening hole with a first insulating layer; providing a first through electrode penetrating the first insulating layer and the valve metal foil in the thickness direction; and electrically connecting the first through electrode and the current collector layer, wherein the dielectric layer, at least a part of which is covered by the solid electrolyte layer, is provided on the first inner circumferential surface of the first opening hole.

[0069] This disclosure can be used in a method for manufacturing electrode sheets.

[0070] 100 Electrolytic capacitor 100A Solid electrolytic capacitor 100B Solid electrolytic capacitor 100C Solid electrolytic capacitor 10 Valve metal foil 10a First main surface 10b Second main surface 11 Core part 12 Porous part 20 Dielectric layer 30 Solid electrolyte layer 40 Current collector layer 50 Sealing part 61 First through electrode 62 Second through electrode 71 First insulating layer 72 Second insulating layer 80 Electrode wiring 90 Terminal electrode (First terminal electrode) 92 Second terminal electrode

Claims

1. A solid electrolytic capacitor comprising: a valve metal foil having a first main surface and a second main surface opposite to the first main surface, and having a porous portion formed at least on the side of the first main surface and a core portion continuous with the porous portion, wherein a dielectric layer is formed on at least a part of the surface of the porous portion; a solid electrolyte layer covering at least a part of the surface of the dielectric layer; a current collector layer covering at least a part of the solid electrolyte layer; a first through electrode penetrating the valve metal foil in the thickness direction and electrically connected to the current collector layer; and a first insulating layer provided between the first through electrode and the valve metal foil, wherein the porous portion is provided with a first opening hole in the portion forming the first through electrode, and the dielectric layer, which is at least a part of which is covered with the solid electrolyte layer, is provided on the first inner circumferential surface of the first opening hole.

2. The solid electrolytic capacitor according to claim 1, wherein the solid electrolyte layer is in contact with the first insulating layer on the first inner surface of the first opening.

3. The solid electrolytic capacitor according to claim 1 or 2, wherein at least a portion of the first opening has a bottom surface restricted by the core, and the dielectric layer is also provided on the bottom surface.

4. The solid electrolytic capacitor according to claim 1 or 2, wherein the porous portion is a sintered body of metal particles fixed to the core portion.

5. The solid electrolytic capacitor according to claim 1 or 2, wherein the valve metal foil is an etched foil, and the porous portion is a roughened portion of the etched foil.

6. The solid electrolytic capacitor according to claim 1 or 2, wherein, when the first main surface is viewed from above, the pattern of the porous portion overlaps with 80% or more of the pattern of the solid electrolyte layer.

7. The solid electrolytic capacitor according to claim 6, wherein, when the first main surface is viewed from above, the pattern of the current collector layer overlaps with the pattern of the solid electrolyte layer such that it does not extend beyond the pattern of the solid electrolyte layer.

8. The solid electrolytic capacitor according to claim 1 or 2, further comprising: a second through electrode that penetrates the valve metal foil in the thickness direction and is electrically connected to the valve metal foil; and a second insulating layer provided between the second through electrode and the valve metal foil, wherein the second through electrode is electrically connected to the valve metal foil at the second main surface.

9. The solid electrolytic capacitor according to claim 1 or 2, further comprising a sealing portion for sealing the valve metal foil, the solid electrolyte layer, and the current collector layer, wherein the first insulating layer is integrally formed with the sealing portion.

10. The solid electrolytic capacitor according to claim 1 or 2, wherein the first insulating layer is a part of the dielectric layer.

11. The solid electrolytic capacitor according to claim 1 or 2, wherein the porous portion is provided on the first main surface side and the second main surface side, respectively.

12. A method for manufacturing a solid electrolytic capacitor, comprising the steps of: preparing a valve metal foil having a first main surface and a second main surface opposite to the first main surface, and having a porous portion formed at least on the side of the first main surface and a core portion continuous with the porous portion, and having a first opening hole for forming a first through electrode; forming a dielectric layer on at least a part of the surface of the porous portion of the valve metal foil; providing a solid electrolyte layer covering at least a part of the surface of the dielectric layer; providing a current collector layer covering at least a part of the solid electrolyte layer; filling the first opening hole with a first insulating layer; providing a first through electrode penetrating the first insulating layer and the valve metal foil in the thickness direction; and electrically connecting the first through electrode and the current collector layer, wherein the dielectric layer, at least a part of which is covered by the solid electrolyte layer, is provided on the first inner circumferential surface of the first opening hole.

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