Solid electrolytic capacitor element and solid electrolytic capacitor

Abstract

Provided is a solid electrolytic capacitor capable of reducing a decrease in capacitance by employing a solid electrolytic capacitor element comprising an anode body 110 having a porous portion in a surface thereof, a dielectric body layer 113 coating the anode body 110, and a cathode portion 130 coating the dielectric body layer 113. The cathode portion 130 includes a solid electrolyte layer 120 coating the dielectric body layer 113. The anode body 110 includes a first anode body portion 111 where the solid electrolyte layer 120 is formed and a second anode body portion 112 where the solid electrolyte layer 120 is not formed. The solid electrolyte layer 120 includes a first solid electrolyte layer disposed in the porous portion, and a second solid electrolyte layer disposed outside the porous portion. The second solid electrolyte layer has a layer thickness greater than or equal to 1 μm in a region R1 between an interface B between the first anode body portion 111 and the second anode body portion 112 and a position at a length of 0.05 L from the interface B toward the first anode body portion 111, where L is the length of the first anode body portion 111 in the longitudinal direction thereof.

Description

[Technical Field]

[0001] The present disclosure relates to a solid electrolytic capacitor element and a solid electrolytic capacitor. [Background technology]

[0002] The solid electrolytic capacitor includes a solid electrolytic capacitor element having a solid electrolyte layer, lead terminals electrically connected to the solid electrolytic capacitor element, and an exterior body sealing the solid electrolytic capacitor element. The solid electrolytic capacitor element includes, for example, an anode body having a porous portion on its surface, a dielectric layer formed on at least a portion of the surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, and a cathode lead layer covering at least a portion of the solid electrolyte layer.

[0003] Patent Document 1 (WO 2013 / 080486) describes a porous material comprising: a substrate made of a valve metal and having a first surface and a second surface opposed to each other; a porous first roughened layer formed on the first surface by vapor deposition of the valve metal and having an outer surface and voids inside; a porous first conductive polymer inner layer formed in the voids of the first roughened layer; a porous first conductive polymer outer layer formed on the outer surface of the first roughened layer; and a porous second conductive polymer outer layer formed on the second surface by vapor deposition of the valve metal and having an outer surface and voids inside. The document discloses "a capacitor comprising: a second roughened layer; a second conductive polymer inner layer formed in the voids of the second roughened layer; a second conductive polymer outer layer formed on the outer surface of the second roughened layer; and a dielectric film formed on the surfaces of the first roughened layer and the second roughened layer, wherein the surface area of ​​the second roughened layer is smaller than the surface area of ​​the first roughened layer, and the second conductive polymer outer layer is thicker than the first conductive polymer outer layer."

[0004] Patent Document 2 (JP Patent Publication No. 11-87177) discloses "a solid electrolytic capacitor using a conductive polymer compound formed by chemical oxidative polymerization as a solid electrolyte, characterized in that the thickness of the conductive polymer compound layer at the center of the capacitor element is at least 0.02 μm." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2013 / 080486 [Patent Document 2] Japanese Patent Application Publication No. 11-87177 Summary of the Invention

[0006] One aspect of the present disclosure relates to a solid electrolytic capacitor element, the solid electrolytic capacitor element including an anode body having a porous portion on its surface, a dielectric layer covering at least a portion of the anode body, and a cathode portion covering at least a portion of the dielectric layer, the cathode portion including a solid electrolyte layer covering at least a portion of the dielectric layer, the anode body including a first anode body portion on which the solid electrolyte layer is formed and a second anode body portion on which the solid electrolyte layer is not formed, the solid electrolyte layer including the first solid electrolyte layer disposed within the porous portion and the second solid electrolyte layer disposed outside the porous portion, and when the longitudinal length of the first anode body is length L, the interface between the first anode body and the second anode body and the ,before The first anode body From the interface of Length 0.05L away Between positions No. 1 In the region, the thickness of the second solid electrolyte layer is 1 μm or more.

[0007] Another aspect of the present disclosure relates to an electrolytic capacitor. , Book Disclosed solid electrolytic capacitor element Contains .

[0008] According to the present disclosure, it is possible to suppress a decrease in the capacitance of a solid electrolytic capacitor. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a cross-sectional view schematically illustrating an example of a capacitor element according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a portion of the capacitor element shown in FIG. [Figure 3] 3 is a cross-sectional view schematically showing another example of the capacitor element of Embodiment 1. FIG. [Figure 4] FIG. 3 is a cross-sectional view schematically illustrating an example of an electrolytic capacitor according to a second embodiment. [Figure 5] FIG. 4 is a cross-sectional view schematically showing another example of the electrolytic capacitor according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Before describing the embodiments, the problems in the prior art will be briefly described below.

[0011] In solid electrolytic capacitors, oxygen from the air outside can penetrate into the capacitor element. When the penetrated oxygen comes into contact with the solid electrolyte layer contained in the capacitor element, the solid electrolyte deteriorates, resulting in a decrease in the capacitance of the solid electrolytic capacitor. The decrease in capacitance due to oxygen penetration becomes more pronounced at high temperatures. In view of the above problems, the present disclosure provides a solid electrolytic capacitor element and a solid electrolytic capacitor that can suppress a decrease in the capacitance of the solid electrolytic capacitor.

[0012] Examples of embodiments of the present disclosure will be described below. Note that in the following description, examples of embodiments of the present disclosure will be described, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and other materials may be applied as long as the effects of the present disclosure can be obtained. In this specification, when a "range between numerical value A and numerical value B" is mentioned, the range includes numerical value A and numerical value B.

[0013] (Solid electrolytic capacitor element) The solid electrolytic capacitor element according to this embodiment includes an anode body having a porous portion on its surface, a dielectric layer covering at least a portion of the anode body, and a cathode portion covering at least a portion of the dielectric layer. The cathode portion includes a solid electrolyte layer covering at least a portion of the dielectric layer. The anode body includes a first anode body portion on which the solid electrolyte layer is formed, and a second anode body portion on which the solid electrolyte layer is not formed. The solid electrolyte layer includes a first solid electrolyte layer disposed within the porous portion, and a second solid electrolyte layer disposed outside the porous portion. When the longitudinal length of the first anode body is length L, the interface between the first anode body and the second anode body is , th 1. Anode body From the interface Length 0.05L away Between positions No. 1 In the region, the thickness of the second solid electrolyte layer is 1 μm or more. Hereinafter, the interface between the first anode body and the second anode body may be referred to as "interface (B)." Furthermore, the solid electrolytic capacitor element according to this embodiment may be referred to as "capacitor element (CE)." Furthermore, , th 1. Anode body From the interface (B) Length 0.05L away The region between the positions may be referred to as "region (R1)."

[0014] As a result of further investigation, the inventors have newly discovered that oxygen may penetrate through the thin portions near the edges of the second solid electrolyte layer, resulting in a decrease in capacitance. The present invention is based on this new finding.

[0015] In the capacitor element (CE), the thickness of the edge (region (R1)) of the second solid electrolyte layer is 1 μm or more. This prevents oxygen from penetrating through the edge. As a result, the capacitor element (CE) and the solid electrolytic capacitor using it are prevented from experiencing a decrease in characteristics (e.g., capacitance) due to oxygen penetration.

[0016] The layer thickness of the second solid electrolyte layer in the region (R1) may be 2 μm or more, or 5 μm or more. The upper limit of the layer thickness of the second solid electrolyte layer in the region (R1) is not particularly limited, but it may be 30 μm or less. These lower and upper limits can be arbitrarily combined as long as there is no contradiction.

[0017] interface (B) and , th one anode body part From the interface (B) length 0.05L away Let the minimum layer thickness of the second solid electrolyte layer in the region between the position be layer thickness T1. . one anode body part From the interface (B) length 0.5L away Let the layer thickness of the second solid electrolyte layer at the position be layer thickness T2. At this time, the layer thickness T1 may be greater than 0.5 times (for example, 0.7 times) of the layer thickness T2. The layer thickness T1 may be less than 3 times (for example, less than 1.5 times) of the layer thickness T2. For example, the layer thicknesses T1 and T2 may satisfy 0.7T2 < T1 < 1.5T2. By satisfying 0.7T2 < T1, the intrusion of oxygen can be particularly suppressed. By satisfying T1 < 1.5T2, the parallelism of the elements can be increased during welding of the anode body part after lamination, and defects such as exposure can be reduced.

[0018] The average layer thickness of the first solid electrolyte layer may be 30 nm or more (for example, 50 nm or more). According to this configuration, the initial electrical characteristics of the solid electrolytic capacitor can be sufficiently exhibited, which is preferable. Here, the average layer thickness is obtained by measuring the thickness of the first solid electrolyte layer at five arbitrary points and averaging the five measured values. The thickness of the first solid electrolyte layer at an arbitrary point can be measured, for example, using an image of a scanning electron microscope (SEM) of the cross section. electronic It can be measured using the image of a microscope (SEM).

[0019] On the surface of the first anode body part, an adhesive containing at least one element selected from the group consisting of C, N, O, and Si may be present. In that case, interface (B) and , th one anode body part From the interface (B) length 0.03L away The amount of the adhesive in the region between the position is , th one anode body part From the interface (B) Length 0.03L away position and 1. Anode body From the interface (B) Length L away The amount of adhesive in the region between the first and second positions is preferably less than the amount of adhesive in the region between the first and second positions. This configuration can prevent the end portions of the second solid electrolyte layer from becoming thin.

[0020] Interface (B) and , th 1. Anode body From the interface (B) Length 0.03L away In the region between the positions, there may be an adhesive containing at least one element selected from the group consisting of C, N, O, and Si. , th 1. Anode body From the interface (B) Length 0.03L away position and 1. Anode body From the interface (B) Length L away It is preferable that no adhesive be present in the region between the first and second positions. This configuration can prevent the edge of the second solid electrolyte layer from thinning. Analysis of the adhesive can be determined, for example, by elemental analysis.

[0021] When manufacturing a solid electrolytic capacitor element, the first anode body In some cases, an adhesive is used in the end portion of the second solid electrolyte layer. For example, wiring for electrolytic polymerization of the solid electrolyte layer may be adhered with an adhesive, or insulating tape may be adhered with an adhesive. The present inventors have newly discovered that the diffusion of such adhesives near the end of the second solid electrolyte layer may cause the end of the second solid electrolyte layer to become thin. By reducing the amount of adhesive remaining near the end of the second solid electrolyte layer, it is possible to prevent the end of the second solid electrolyte layer from becoming thin.

[0022] Examples of the adhesive containing at least one element selected from the group consisting of C, N, O, and Si include acrylic adhesives and silicone adhesives.

[0023] In a capacitor element (CE), it is preferable to prevent oxygen from penetrating from the second anode body into the solid electrolyte layer. Therefore, a material with high oxygen barrier properties is preferably present on the surface of the portion of the second anode body adjacent to the first anode body. Examples of such materials include insulating resins, compositions containing insulating resins, insulating tape, and metals with substantially no voids. For example, the oxygen barrier properties of the portion of the second anode body adjacent to the first anode body may be improved by removing or compressing the porous portion. Alternatively, an insulating resin (or a composition containing an insulating resin) may be applied to the porous portion of the portion of the second anode body adjacent to the first anode body, or insulating tape may be placed on the porous portion.

[0024] The second anode body may include an anode end portion and a separator portion disposed between the anode end portion and the first anode body portion. In this case, a first insulating resin may be disposed on at least a portion of the separator portion. This configuration can prevent a short circuit between the anode end portion and the cathode body. Furthermore, this configuration can prevent oxygen from entering through the separator portion. When the separator portion has a porous portion on its surface, the first insulating resin may be disposed in the voids of the porous portion. arrangement It may be done.

[0025] Examples of the first insulating resin include an insulating tape (such as a resist tape) containing the first insulating resin, a coating containing the first insulating resin, etc. That is, a resin composition containing the first insulating resin may be disposed in at least a part of the separating portion.

[0026] The first insulating resin may be a thermoplastic resin or a curable resin. The number of types of insulating resins contained in the first insulating resin may be one or two or more. Examples of thermoplastic resins include polyolefin, polyester, polyamide, and thermoplastic polyimide. The curable resin may be a thermosetting resin or a photocurable resin. Examples of photocurable resins include those that are cured by ultraviolet light or visible light. Examples of thermosetting resins include epoxy resin, phenolic resin, unsaturated polyester resin, thermosetting polyurethane resin, thermosetting polyimide, and photoresist. The resin composition containing the first insulating resin may contain components other than the first insulating resin (e.g., a curing agent, a curing accelerator, a catalyst, an additive, etc.).

[0027] When the second anode body includes an anode end portion and a separation portion, the second anode body may have a recess formed in the separation portion. The first insulating resin described above may be disposed in the recess. For example, an insulating tape (e.g., resist tape) containing the first insulating resin may be disposed in the recess.

[0028] The capacitor element (CE) may include a second insulating resin disposed on the outer surface of a portion of the second solid electrolyte layer adjacent to the interface (B). This configuration can prevent a short circuit between the anode end and the cathode. Furthermore, this configuration can particularly prevent oxygen from entering through the second solid electrolyte layer.

[0029] The second insulating resin may be a thermoplastic resin or a curable resin. The number of types of insulating resins contained in the second insulating resin may be one or two or more. The first insulating resin and the second insulating resin may be the same or different.

[0030] Examples of thermoplastic resins used as the second insulating resin include at least one selected from the group consisting of vinyl resins (e.g., vinyl chloride, vinyl acetate, aromatic vinyl resins), polyolefins (e.g., polyethylene, polypropylene), acrylic resins, polyamides, polycarbonates, thermoplastic polyimides, and polyamideimides. Examples of aromatic vinyl resins include polystyrene and acrylonitrile-butadiene-styrene copolymers (ABS resins). Examples of curable resins used as the second insulating resin may include those exemplified as the second insulating resin.

[0031] The second insulating resin may be disposed on the second solid electrolyte layer, for example, by applying a coating liquid or a resin composition containing the second insulating resin onto the second solid electrolyte layer and drying or curing the coating liquid or resin composition.

[0032] (Example of components of a capacitor element (CE)) Examples of components of the capacitor element (CE) are described below. Known components may be used for components other than those characteristic of the present disclosure.

[0033] (anode body) As described above, the anode body includes a first anode body portion on which a solid electrolyte layer is formed and a second anode body portion on which a solid electrolyte layer is not formed. The anode body can include a valve metal, an alloy containing a valve metal, a compound containing a valve metal, or the like. These materials can be used alone or in combination. Examples of preferred valve metals include aluminum, tantalum, niobium, and titanium. An anode body having a porous portion on its surface can be obtained, for example, by roughening the surface of a metal foil containing a valve metal. The roughening can be performed by electrolytic etching or the like. The entire anode body may be porous. However, from the viewpoint of strength, the anode body preferably includes porous portions disposed on both main surfaces and a core portion disposed between the porous portions. The porosity of the core portion is lower than that of the porous portion. The porous portion is a region having numerous fine pores. The core portion is, for example, a region that has not been electrolytically etched.

[0034] (dielectric layer) The dielectric layer is an insulating layer that functions as a dielectric. The dielectric layer may be formed by anodizing a valve metal on the surface of the anode body (e.g., a metal foil). The dielectric layer may be formed so as to cover at least a portion of the anode body. The dielectric layer is usually formed on the surface of the anode body. Since the dielectric layer is formed on the surface of the porous portion of the anode body, it is formed along the inner wall surfaces of holes and depressions (also called pits) on the surface of the anode body.

[0035] A typical dielectric layer contains an oxide of a valve metal. For example, when tantalum is used as the valve metal, a typical dielectric layer contains Ta2O5, and when aluminum is used as the valve metal, a typical dielectric layer contains Al2O3. However, the dielectric layer is not limited to these and may be any material that functions as a dielectric.

[0036] (cathode) The cathode section includes a solid electrolyte layer covering at least a portion of the dielectric layer, and may further include a cathode extraction layer covering at least a portion of the solid electrolyte layer. The solid electrolyte layer and the cathode extraction layer will be described below.

[0037] (solid electrolyte layer) As described above, the solid electrolyte layer includes a first solid electrolyte layer disposed within the porous portion of the anode body (more specifically, the void portion of the porous portion) and a second solid electrolyte layer disposed outside the porous portion.

[0038] The solid electrolyte layer includes a conductive polymer. The solid electrolyte layer may further include at least one selected from the group consisting of a dopant and other additives, as needed. Examples of dopants include, but are not limited to, paratoluenesulfonic acid, naphthalenesulfonic acid, and polystyrenesulfonic acid (PSS).

[0039] As the conductive polymer, for example, a π-conjugated polymer can be used. Examples of the conductive polymer include polymers having a basic skeleton of polypyrrole, polythiophene, polyaniline, polyfuran, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polythiophene vinylene. The above polymers also include homopolymers, copolymers of two or more monomers, and derivatives thereof (e.g., substituted products having substituent groups). For example, polythiophenes include poly(3,4-ethylenedioxythiophene). However, these are merely examples, and the conductive polymer is not limited to these examples.

[0040] The solid electrolyte layer may be formed so as to cover at least a portion of the dielectric layer. The solid electrolyte layer may be formed directly on the dielectric layer, or may be formed via a conductive precoat layer. The precoat layer may be formed, for example, from a conductive material (such as a conductive polymer or an inorganic conductive material). The conductive material constituting the precoat layer is not particularly limited, and for example, a known material may be used.

[0041] (Cathode extraction layer) The cathode extraction layer may include at least a first layer that is in contact with the solid electrolyte layer and covers at least a portion of the solid electrolyte layer, and may include a first layer and a second layer that covers the first layer. Examples of the first layer include a layer containing conductive particles and metal foil. Examples of the conductive particles include at least one selected from conductive carbon and metal powder. For example, the cathode extraction layer may be formed by using a layer containing conductive carbon (hereinafter sometimes referred to as a "carbon layer") as the first layer and a layer containing metal powder or metal foil as the second layer, with these two layers forming the cathode extraction layer. When metal foil is used as the first layer, the cathode extraction layer may be formed by this metal foil. Examples of conductive carbon include graphite (artificial graphite, natural graphite, etc.).

[0042] When a layer containing metal powder is used as the second layer, the second layer may be formed by laminating a composition containing metal powder on the surface of the first layer. An example of such a second layer is a metal paste layer formed using a composition containing metal powder such as silver particles and a resin (binder resin). While a thermoplastic resin can be used as the resin, it is preferable to use a thermosetting resin such as an imide resin or an epoxy resin.

[0043] When a metal foil is used as the first layer, the type of metal is not particularly limited, but it is preferable to use a valve metal such as aluminum, tantalum, or niobium, or an alloy containing a valve metal. If necessary, the surface of the metal foil may be roughened. The surface of the metal foil may be provided with a chemical conversion coating, or may be provided with a coating of a metal (dissimilar metal) or a nonmetal different from the metal constituting the metal foil. Examples of dissimilar metals and nonmetals include metals such as titanium and nonmetals such as carbon (e.g., conductive carbon).

[0044] The coating of the dissimilar metal or non-metal (for example, conductive carbon) may be the first layer, and the metal foil may be the second layer.

[0045] (Solid electrolytic capacitor) The solid electrolytic capacitor according to this embodiment includes at least one solid electrolytic capacitor element. The solid electrolytic capacitor element is the capacitor element (CE) described above. The solid electrolytic capacitor may include solid electrolytic capacitor elements other than the capacitor element (CE). In a preferred example, all of the solid electrolytic capacitor elements included in the solid electrolytic capacitor are capacitor elements (CE). The number of solid electrolytic capacitor elements included in the solid electrolytic capacitor may be in the range of 1 to 20 (for example, in the range of 2 to 20).

[0046] When the electrolytic capacitor includes a plurality of capacitor elements (CE), the capacitor elements (CE) may be stacked. 2 The anode body portions (e.g., anode ends) are electrically connected to each other. 2 The anode body parts may be joined by welding. 2 The anode body may be welded to the anode lead terminal after being crimped thereto. 2 An anode lead terminal may be joined to the anode body.

[0047] Typically, the cathode extraction layers of the stacked capacitor elements are electrically connected to each other. A cathode lead terminal may be bonded to the cathode extraction layer of at least one capacitor element. The cathode lead terminal may be bonded to the cathode extraction layer via a conductive adhesive or solder. Alternatively, the cathode lead terminal may be bonded to the cathode extraction layer by welding (resistance welding, laser welding, etc.). The conductive adhesive is, for example, a mixture of a curable resin and carbon particles or metal particles.

[0048] The solid electrolytic capacitor may further include an exterior body and / or a case that seals the at least one solid electrolytic capacitor element. The case may include a container such as a bottomed case and a sealing body that seals the opening of the container. Examples of materials that can be used to form the container and the sealing body include metal materials and resin materials.

[0049] The exterior body preferably contains a cured product of a curable resin composition, and may contain a thermoplastic resin or a composition containing the same. The curable resin composition may contain a curable resin and a filler. The curable resin is preferably a thermosetting resin. Examples of resin materials constituting the case include thermoplastic resins and compositions containing thermoplastic resins. Examples of metal materials constituting the case include metals such as aluminum, copper, and iron, or alloys thereof (including stainless steel, brass, etc.).

[0050] Yang One end of the electrode lead terminal and one end of the cathode lead terminal are exposed to the outside of the exterior body or case, and are used for soldering to a substrate on which the solid electrolytic capacitor is mounted.

[0051] (Solid electrolytic capacitor element and method of manufacturing a solid electrolytic capacitor) There are no particular limitations on the manufacturing methods of the capacitor element (CE) and solid electrolytic capacitor according to this embodiment. For their manufacturing methods, known manufacturing methods may be applied, or known manufacturing methods may be partially modified, except for controlling the thickness of the second solid electrolyte layer.

[0052] An example of a method for manufacturing the capacitor element (CE) and solid electrolytic capacitor according to this embodiment will be described below. However, the capacitor element (CE) and solid electrolytic capacitor according to this embodiment may be manufactured by a method other than the method described below. The matters described for the capacitor element (CE) and solid electrolytic capacitor are also applicable to the manufacturing method below, so duplicated explanations may be omitted. Furthermore, the matters described for the manufacturing method below are also applicable to the capacitor element (CE) and solid electrolytic capacitor according to this embodiment.

[0053] An example of a method for manufacturing a solid electrolytic capacitor includes the steps of fabricating a capacitor element, electrically connecting lead terminals to the capacitor element, and covering the capacitor element and a portion of the lead terminals with an exterior body. An example of these steps is described below.

[0054] (Process for producing capacitor element) A capacitor element is fabricated by the following procedure. The process for fabricating the capacitor element includes the steps of forming an anode body having a porous portion, forming a dielectric layer on the surface of the anode body, forming a solid electrolyte layer, and forming a cathode extraction layer. The method for manufacturing a solid electrolytic capacitor may further include the step of forming a separator before the step of forming the solid electrolyte layer.

[0055] (1) A step of forming an anode body having a porous portion The raw material for the anode body is, for example, a metal foil containing a valve metal. The porous portion can be formed, for example, by roughening the surface of the metal foil containing the valve metal. Roughening the surface forms a porous portion in the surface layer of the anode body (metal foil). An unroughened base portion may exist inside the metal foil. Roughening may be performed, for example, by etching (e.g., electrolytic etching) the surface of the metal foil.

[0056] (2) Forming a dielectric layer In this step, a dielectric layer is formed on the anode body. The dielectric layer may be formed by anodizing the surface of the metal foil that will become the anode body. The anodization may be performed by a known method, such as chemical conversion treatment. The chemical conversion treatment may be performed by applying a voltage between the anode body (anode) immersed in a chemical conversion solution and a cathode immersed in the chemical conversion solution. For example, an aqueous solution of phosphoric acid is preferably used as the chemical conversion solution.

[0057] The step of forming the dielectric may be performed in one step or multiple steps. For example, a dielectric layer may be formed, and then another step may be performed, followed by another step of forming a dielectric layer.

[0058] When forming a separating portion on the anode body, the anode body (metal foil) before or after forming the dielectric layer is separated into the anode end, the separating portion, and the first 1The anode body is divided into an anode body portion and a separator portion. For example, the separator portion may be formed by thinning a part of the anode body. The thinned portion may be formed by compressing or removing a porous portion in the region that will become the separator portion. Compression may be performed by press working or the like. Removal of the porous portion may be performed by cutting work, laser processing or the like.

[0059] A separating member may be disposed on the surface of the separating portion. By performing the step of disposing the separating member before the step of forming the solid electrolyte layer, it is possible to prevent conductive polymers from being formed on the anode end side when the solid electrolyte layer is formed. When the separating member is bonded with an adhesive, the adhesive strength of the separating member may be increased by heating. Increasing the heating temperature makes it easier for the adhesive to diffuse into the second anode body. In areas where the adhesive has diffused, the second solid electrolyte layer may become thinner. Therefore, it is preferable not to heat the separating member when bonding it, or to use a low heating temperature (for example, 70°C or lower).

[0060] (3) Forming a solid electrolyte layer The solid electrolyte layer may be formed, for example, by using a treatment solution containing a precursor of a conductive polymer and polymerizing the precursor on the dielectric layer. The polymerization may be performed by at least one of chemical polymerization and electrolytic polymerization. In the case of electrolytic polymerization, a conductive precoat layer may be formed prior to the electrolytic polymerization. Examples of the precursor of the conductive polymer include at least one selected from the group consisting of a monomer, an oligomer, and a prepolymer.

[0061] The solid electrolyte layer may be formed by applying a treatment liquid (e.g., a dispersion or solution) containing a conductive polymer to the dielectric layer and then drying the applied liquid. Examples of the dispersion medium (or solvent) include water, an organic solvent, or a mixture thereof. The treatment liquid may further contain other components (e.g., at least one selected from the group consisting of a dopant and an additive).

[0062] A part of the solid electrolyte layer is formed inside the porous portion (more specifically, in the voids of the porous portion), and another part is formed outside the porous portion, resulting in the formation of a first solid electrolyte layer disposed inside the porous portion and a second solid electrolyte layer disposed outside the porous portion.

[0063] When forming a solid electrolyte layer by electrolytic polymerization, electrolytic polymerization may be performed with a conductive tape for supplying power placed near the second anode body. In this case, the adhesive for securing the conductive tape may diffuse into the second anode body. The second solid electrolyte layer may become thinner in areas where the adhesive has diffused. Therefore, when placing the conductive tape near the second anode body, it is preferable to maintain a constant distance between the second anode body and the conductive tape. This can reduce variations in the thickness of the second solid electrolyte layer and prevent the second solid electrolyte layer from becoming locally thin.

[0064] Let us consider the case where a solid electrolyte layer is formed by electrolytic polymerization after forming a precoat layer. In this case, if the precoat layer near the interface B is not sufficiently formed, the second solid electrolyte layer near the interface B may become thin. Therefore, it is important to form the precoat layer sufficiently up to the vicinity of the interface B. For example, when forming a precoat layer, it is necessary to form the precoat layer so that the thickness of the second solid electrolyte layer near the interface B is , th 1. Anode body From interface B of Length 0.05L away It is preferable that the precoat layer is also formed in the region between the positions.

[0065] (4) Step of forming a cathode extraction layer In this process, a cathode extraction layer is formed on the surface of the solid electrolyte layer. The cathode extraction layer can be formed, for example, by applying a carbon paste and a silver paste in that order to the solid electrolyte layer. In this way, a capacitor element (CE) is formed.

[0066] (5) Manufacturing of solid electrolytic capacitors Next, a solid electrolytic capacitor is manufactured using the capacitor element (CE) by the following method: An example of a method for manufacturing a solid electrolytic capacitor including a plurality of capacitor elements (CE) will be described below.

[0067] First, a laminate is produced by stacking multiple capacitor elements (CE). The anode ends of the multiple capacitor elements are electrically connected to each other by joining them by welding and / or crimping, etc. Adjacent cathode extraction layers may be connected by metal paste, etc. If necessary, an anode lead terminal is connected to the anode terminal portion, and a cathode lead terminal is connected to the cathode extraction layer.

[0068] In this manner, a laminate of multiple capacitor elements (CE) is obtained. Next, the obtained laminate and some of the lead terminals are sealed with an exterior body. The sealing may be performed using a known molding technique (injection molding, insert molding, compression molding, etc.). For example, a predetermined mold may be used to arrange the exterior body material (resin composition) so as to cover the stacked solid electrolytic capacitor elements and some of the lead terminals, and then heating may be performed. In this manner, the exterior body is formed.

[0069] Examples of embodiments according to the present disclosure will be described in detail below with reference to the drawings. The components described above can be applied to the components of the examples described below. The examples described below can be modified based on the above description. The matters described below may also be applied to the above-described embodiments. In the embodiments described below, components that are not essential for the solid electrolytic capacitor element and solid electrolytic capacitor of the present disclosure may be omitted. The solid electrolytic capacitor element and solid electrolytic capacitor described below may be manufactured by the above-described method. Note that the following drawings are schematic and may differ from the actual configuration.

[0070] (Embodiment 1) FIG. 1 is a cross-sectional view schematically illustrating a solid electrolytic capacitor element according to Embodiment 1. Capacitor element 100 shown in FIG. 1 includes an anode body 110, a dielectric layer 113 covering at least a portion of anode body 110, and a cathode section 130 covering at least a portion of dielectric layer 113. Cathode section 130 includes a solid electrolyte layer 120 covering at least a portion of dielectric layer 113, and a cathode extraction layer 131 covering at least a portion of solid electrolyte layer 120. Cathode extraction layer 131 includes a carbon layer 131a disposed on solid electrolyte layer 120, and a metal paste layer 131b disposed on carbon layer 131a. Of the surfaces of anode body 110, the main surface on which solid electrolyte layer 120 is formed is roughened to form a porous portion (see FIG. 2).

[0071] The anode body 110 includes a first anode body 111 and a second anode body 112. A solid electrolyte layer 120 is disposed on the first anode body 111. No solid electrolyte layer is disposed on the second anode body 112. The second anode body 112 includes an anode end portion 112a and a separator portion 112b. The separator portion 112b is disposed between the anode end portion 112a and the first anode body 111.

[0072] In FIG. 1, for ease of understanding, the interface B between the first anode body and the second anode body is indicated by a dotted line. The interface between the anode end 112a and the separation portion 112b is also indicated by a dotted line. The separation portion 112b is thinner than other portions of the anode body 110. A separation member 140 is disposed on the separation portion 112b. The separation member 140 has insulating properties. The separation member 140 may contain the first insulating resin described above.

[0073] The length of the first anode body 111 in the longitudinal direction is represented by L. FIG. 1 shows an interface B between the first anode body and the second anode body. , th Anode body 111 of 1 From interface B of Length 0.05L away Furthermore, Fig. 1 shows the region R1 between the interface B and , th Anode body 111 of 1 From interface B of Length 0.03L awayThe lengths 0.03L and 0.05L are lengths along the longitudinal direction of first anode body 111.

[0074] An enlarged cross-sectional view of the solid electrolyte layer 120 formed on the first anode body 111 is shown in FIG. 2. As shown in FIG. 2, the first anode body 111 has a porous portion 111a on its surface. The solid electrolyte layer 120 is made up of a first solid electrolyte layer 121 disposed in the porous portion 111a and a porous portion 111b. 111a and a second solid electrolyte layer 122 disposed outside the first anode body 111. In other words, the second solid electrolyte layer 122 is disposed outside the first anode body 111. The first solid electrolyte layer 121 and the second solid electrolyte layer 122 are connected to each other to form the solid electrolyte layer 120.

[0075] 2 shows the thickness ta of the first solid electrolyte layer 121 and the thickness tb of the second solid electrolyte layer 122 at a certain point P. There are irregularities at the boundary between the porous portion 111a and other portions. However, because the irregularities are minute compared to the thickness of the solid electrolyte layer, it is possible to regard the boundary between the porous portion 111a and other portions as a flat surface when measuring the thickness of the solid electrolyte layer.

[0076] As described above, the interface B between the first anode body 111 and the second anode body 112 , th Anode body 111 of 1 From interface B of Length 0.05L away In a region R1 between the positions, the thickness of second solid electrolyte layer 122 is 1 μm or more. This configuration can prevent oxygen from entering the portion of first solid electrolyte layer 121 through the thin portion of second solid electrolyte layer 122. Therefore, deterioration of the device characteristics due to oxygen can be prevented.

[0077] Interface B and , th Anode body 111 of 1 From interface B of Length 0.05L away The minimum thickness of the second solid electrolyte layer 122 in the region between the positions is defined as the layer thickness T1. . Anode body 111 of 1 From interface B of Length 0.5L awayThe thickness of the second solid electrolyte layer 122 at the position is defined as thickness T2. Thicknesses T1 and T2 may satisfy the relationship described above. Furthermore, the average thickness of the first solid electrolyte layer may be within the range described above.

[0078] When an adhesive containing at least one element selected from the group consisting of C, N, O, and Si is present on the surface of first anode body 111, the amount of adhesive may be the amount described above.

[0079] A layer containing the second insulating resin described above may be formed on the outer surface of a portion of second solid electrolyte layer 122 adjacent to interface B. FIG. 3 shows a schematic cross-sectional view of capacitor element 100 including such layer 142. Layer 142 is formed so as to cover the portion of second solid electrolyte layer 122 adjacent to interface B. The portion of second solid electrolyte layer 122 near interface B is likely to thin. The configuration shown in FIG. 3 can reduce the amount of oxygen that permeates second solid electrolyte layer 122, which is likely to thin.

[0080] (Embodiment 2) 4 is a cross-sectional view schematically showing a solid electrolytic capacitor according to Embodiment 2. The electrolytic capacitor 200 shown in FIG. 4 includes a capacitor element 100, an anode lead terminal 211, a cathode lead terminal 212, and an outer casing 230.

[0081] Anode lead terminal 211 is connected to anode end 112a. Cathode lead terminal 212 is connected to cathode extraction layer 131 via conductive member 213 such as metal paste. A portion of anode lead terminal 211 and a portion of cathode lead terminal 212 are exposed from exterior body 230. The exposed portions function as terminals. Exterior body 230 is arranged to cover the entire capacitor element 100.

[0082] Electrolytic capacitor 200 uses capacitor element 100. Therefore, electrolytic capacitor 200 can suppress a decrease in capacitance due to oxygen.

[0083] The solid electrolytic capacitor according to the present disclosure may include a plurality of capacitor elements. An example of a solid electrolytic capacitor including a plurality of capacitor elements 100 is shown schematically in Fig. 5. The electrolytic capacitor 200 in Fig. 5 includes a plurality of capacitor elements 100 stacked and connected in parallel. The plurality of capacitor elements 100 are covered with an exterior body 230. [Example]

[0084] The solid electrolytic capacitor element and solid electrolytic capacitor according to the present disclosure will be described in further detail with reference to examples.

[0085] [Fabrication and evaluation of electrolytic capacitor A1] A solid electrolytic capacitor (electrolytic capacitor A1) was fabricated by the method described below. The electrolytic capacitor A1 includes seven capacitor elements stacked and connected in parallel. Each capacitor element has a structure similar to that of the capacitor element 100 described in the first embodiment.

[0086] (1) Fabrication of capacitor elements First, the surface of an aluminum foil (thickness 100 μm) was etched to obtain an anode foil (anode body) with a porous portion disposed on the surface. This anode foil was immersed in a 0.3 mass% phosphoric acid solution (liquid temperature 70°C) and a DC voltage of 70 V was applied for 20 minutes. This voltage application formed a dielectric layer containing aluminum oxide (Al2O3) on the surface of the anode foil.

[0087] Next, a recess was formed by compressing the portion of the anode foil that would become the separation portion using a press. An insulating resist tape (separation member) was then attached to the recess. The separation member was then firmly attached to the recess by heat treatment. The heat treatment was carried out at 70°C for 24 hours. In this way, a separation portion in which the separation member was located was formed.

[0088] Next, the anode foil with the separator formed thereon was immersed in a liquid composition containing a conductive material to form a precoat layer on the anode foil. The precoat layer was formed in the area where the solid electrolyte layer was to be formed. Next, a polymerization solution containing pyrrole (a monomer for a conductive polymer), naphthalenesulfonic acid (a dopant), and water was prepared. The anode foil with the precoat layer formed thereon was immersed in the obtained polymerization solution. While the anode foil was immersed in the polymerization solution, electrolytic polymerization was performed at an applied voltage of 3 V to form a solid electrolyte layer. This process formed a first solid electrolyte layer disposed within the porous portion of the anode foil and a second solid electrolyte layer disposed outside the porous portion.

[0089] Next, a dispersion liquid in which graphite particles were dispersed in water was applied to the solid electrolyte layer and then dried. This formed a carbon layer on the surface of the solid electrolyte layer. Next, a silver paste containing silver particles and a binder resin (epoxy resin) was applied to the surface of the carbon layer, and the binder resin was then cured by heating. This formed a metal paste layer (silver paste layer). In this way, a cathode extraction layer composed of the carbon layer and the silver paste layer was formed. In this way, a cathode part composed of the solid electrolyte layer and the cathode extraction layer was formed.

[0090] (2) Assembling electrolytic capacitor A1 Seven capacitor elements were fabricated using the above method. A laminate was fabricated by stacking the seven capacitor elements. The anode terminals were connected to each other, and the silver paste layers were connected to each other with a conductive adhesive. An anode lead terminal was connected to the anode terminal, and a cathode lead terminal was connected to the cathode extraction layer. The resulting laminate was sealed with resin. In this way, an electrolytic capacitor A1 was obtained, including seven capacitor elements stacked and connected in parallel, and an exterior covering covering them.

[0091] (3) Measurement of the thickness of the second solid electrolyte layer For electrolytic capacitor A1, interface B and 1. Anode body From interface B of Length 0.05L awayThe thickness of the second solid electrolyte layer was measured in the region between the positions (region R1 in Figure 1). Here, interface B is the interface between the first anode body portion on which the solid electrolyte layer is formed and the second anode body portion on which the solid electrolyte layer is not formed. The thickness of the second solid electrolyte layer was measured by the following method. First, the cross section of the element shown in Figure 1 was polished to expose the cross section near the center of the element. The thickness of the second solid electrolyte layer was measured by observing the cross section with an optical microscope (magnification 1000x). Specifically, the thickness T1 of the thinnest point of the second solid electrolyte layer in region R1 in Figure 1 was measured. , th 1. Anode body From interface B of Length 0.5L away The thickness T2 of the second solid electrolyte layer at the position was measured.

[0092] Furthermore, the electrolytic capacitor A1 was evaluated for the presence or absence of adhesive in the region R2 using the method described above.

[0093] (4) Measurement of the rate of change in capacitance due to exposure to high temperatures The initial capacitance F0 of electrolytic capacitor A1 was measured using a four-terminal LCR meter in a 20°C environment. Next, electrolytic capacitor A1 was left in a 165°C atmosphere for 200 hours (high-temperature storage). After that, the capacitance F1 of electrolytic capacitor A1 after high-temperature storage was measured in the same manner as the initial capacitance F0. The rate of change in capacitance was then calculated using the following formula: Capacitance change rate (%) = (F1-F0) / F0 x 100

[0094] [Fabrication and Evaluation of Electrolytic Capacitors A2 to A4 and C1] Except for some changes in the manufacturing conditions, electrolytic capacitors A2 to A4 and C1 were fabricated under the same conditions and by the same method as electrolytic capacitor A1. Specifically, the conditions (temperature and / or time) of the heat treatment when adhering the separating member to the recess were changed. The lower the temperature of this heat treatment, the less adhesive there is in region R2, and the thicker the second solid electrolyte layer in region R1 tends to be. Furthermore, the shorter the heat treatment time, the less adhesive there is in region R2, and the thicker the second solid electrolyte layer in region R1 tends to be. Specifically, the heat treatment conditions were changed as follows: Electrolytic capacitor A2: 24 hours at 60°C Electrolytic capacitor A3: 24 hours at 50°C Electrolytic capacitor A4: 48 hours at 70°C Electrolytic capacitor C1: 24 hours at 100°C

[0095] The produced electrolytic capacitors were evaluated in the same manner as electrolytic capacitor A1, and the evaluation results are shown in Table 1. A capacitance change rate of −20% or less was determined to be defective.

[0096] [Table 1]

[0097] As shown in Table 1, electrolytic capacitors A1 to A4, in which the thickness of the second solid electrolyte layer in region R1 was 1 μm or more, maintained a high capacitance even after being left at high temperature. This is thought to be because oxygen penetration from region R1 was suppressed. When the thickness of the second solid electrolyte layer in region R1 was 5 μm or more (e.g., 6 μm or more), the capacitance after being left at high temperature was particularly high. On the other hand, in electrolytic capacitor C1, in which the second solid electrolyte layer in region R1 was thin, the capacitance after being left at high temperature decreased significantly. [Industrial Applicability]

[0098] The present disclosure can be used for solid electrolytic capacitor elements and solid electrolytic capacitors. [Explanation of symbols]

[0099] 100: Capacitor element 110: Anode body 111: First anode body 111a: Porous part 112: Second anode body 112a:Anode end 112b: Separation part 113: Dielectric layer 120: Solid electrolyte layer 121: First solid electrolyte layer 122: Second solid electrolyte layer 130: Cathode 200: Electrolytic capacitor B: Interface

Claims

1. an anode body having a porous portion on its surface; a dielectric layer covering at least a portion of the anode body; a cathode portion covering at least a portion of the dielectric layer, the cathode portion includes a solid electrolyte layer covering at least a portion of the dielectric layer, the anode body includes a first anode body portion on which the solid electrolyte layer is formed and a second anode body portion on which the solid electrolyte layer is not formed, the solid electrolyte layer includes a first solid electrolyte layer disposed within the porous portion and a second solid electrolyte layer disposed outside the porous portion; When the length of the first anode body in the longitudinal direction is L, a thickness of the second solid electrolyte layer is 1 μm or more in a first region between an interface between the first anode body and the second anode body and a position of the first anode body that is 0.05 L away from the interface; an adhesive containing at least one element selected from the group consisting of C, N, O, and Si is present on a surface of the first anode body; a solid electrolytic capacitor element, wherein the amount of adhesive in a second region between the interface and a position of the first anode body that is 0.03 L away from the interface is less than the amount of adhesive in a third region between a position of the first anode body that is 0.03 L away from the interface and a position of the first anode body that is 0.03 L away from the interface.

2. an anode body having a porous portion on its surface; a dielectric layer covering at least a portion of the anode body; a cathode portion covering at least a portion of the dielectric layer, the cathode portion includes a solid electrolyte layer covering at least a portion of the dielectric layer, the anode body includes a first anode body portion on which the solid electrolyte layer is formed and a second anode body portion on which the solid electrolyte layer is not formed, the solid electrolyte layer includes a first solid electrolyte layer disposed within the porous portion and a second solid electrolyte layer disposed outside the porous portion; When the length of the first anode body in the longitudinal direction is L, a thickness of the second solid electrolyte layer is 1 μm or more in a first region between an interface between the first anode body and the second anode body and a position of the first anode body that is 0.05 L away from the interface; an adhesive containing at least one element selected from the group consisting of C, N, O, and Si is present in a second region between the interface and a position of the first anode body that is 0.03 L away from the interface; A solid electrolytic capacitor element, wherein the adhesive is not present in a third region between a position at a length of 0.03L from the interface toward the first anode body and a position at a length of L from the interface toward the first anode body.

3. 3. The solid electrolytic capacitor element according to claim 1, wherein a minimum thickness T1 of the second solid electrolyte layer in the first region and a thickness T2 of the second solid electrolyte layer at a position 0.5L away from the interface of the first anode body satisfy 0.7T2<T1<1.5T2.

4. 4. The solid electrolytic capacitor element according to claim 1, wherein the first solid electrolyte layer has an average thickness of 30 nm or more.

5. the second anode body includes an anode end portion and a separator portion disposed between the anode end portion and the first anode body portion; 5. The solid electrolytic capacitor element according to claim 1, wherein a first insulating resin is disposed on at least a part of the separating portion.

6. The solid electrolytic capacitor element according to claim 5 , wherein the second anode body has a recess formed in the separating portion.

7. 7. The solid electrolytic capacitor element according to claim 1, further comprising a second insulating resin disposed on the outer surface of the second solid electrolyte layer in a portion adjacent to the interface.

8. A solid electrolytic capacitor comprising the solid electrolytic capacitor element according to any one of claims 1 to 7.

9. The solid electrolytic capacitor according to claim 8 , comprising a plurality of the solid electrolytic capacitor elements stacked one on top of the other.

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