Electrolytic capacitor

Abstract

The disclosed electrolytic capacitor includes at least one capacitor element (100), a first lead terminal (20) and a second lead terminal connected to the capacitor element (100), and an exterior body (40) covering a part of the first lead terminal (20), a part of the second lead terminal, and the at least one capacitor element. The first lead terminal (20) includes an embedded part (21) embedded in the exterior body, and an exposed part (22) exposed from the exterior body (40). The first lead terminal (20) has two main surfaces and a lead side surface (20Ls) connecting the two main surfaces. The exterior body (40) has a first end surface (40Pe1) on which the exposed part of the first lead terminal (20) protrudes, and a second end surface on a side opposite to the first end surface (40Pe1). The embedded part (21) includes a protruding part (21X) protruding from the lead side surface (20Ls).

Description

electrolytic capacitor CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This disclosure claims the benefit of priority to Japanese Patent Application No. 2024-053525, filed on March 28, 2024, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to electrolytic capacitors.

[0003] An electrolytic capacitor includes a capacitor element, lead terminals connected to the capacitor element, and an exterior body that covers the capacitor element. Various proposals have been made regarding electrolytic capacitors.

[0004] Claim 1 of Patent Document 1 (JP 2011-91444 A) describes a capacitor element in which a dielectric oxide film, a solid electrolyte layer, and a cathode layer are sequentially laminated on the surface of an anode part made of a valve metal and having an anode lead part, and a plurality of such capacitor elements are laminated, and the anode part is joined to the anode lead part of the capacitor element, and the anode part is formed from a film in which a conductive filler and a binder resin are mixed, and has a volume resistivity of 10.0 × 10 －４ and a cathode portion formed by joining the cathode layer of the capacitor element via a conductive sheet having a resistance of Ω·cm or less.

[0005] JP 2011-91444 A

[0006] Electrolytic capacitors are required to have reduced degradation, and one of the objects of the present disclosure is to provide an electrolytic capacitor that exhibits less degradation.

[0007] One aspect of the present disclosure relates to an electrolytic capacitor including: at least one capacitor element; a first lead terminal and a second lead terminal connected to the at least one capacitor element; and an exterior body covering a portion of the first lead terminal, a portion of the second lead terminal, and the at least one capacitor element, wherein the first lead terminal includes an embedded portion embedded in the exterior body and an exposed portion exposed from the exterior body, the first lead terminal having two main surfaces and a lead side surface Ls connecting the two main surfaces, the exterior body having a first end surface Pe1 from which the exposed portion of the first lead terminal protrudes and a second end surface Pe2 opposite the first end surface Pe1, and the embedded portion includes a protruding portion protruding from the lead side surface Ls.

[0008] According to the present disclosure, an electrolytic capacitor with little deterioration can be obtained. The novel features of the present invention are set forth in the appended claims, but the present invention, both in terms of structure and content, together with other objects and features of the present invention, will be better understood from the following detailed description taken in conjunction with the drawings.

[0009] Fig. 1 is a cross-sectional view schematically showing an example of an electrolytic capacitor according to embodiment 1. Fig. 2 is a top view of the electrolytic capacitor shown in Fig. 1. Fig. 3 is a cross-sectional view schematically showing an example of a capacitor element. Fig. 4 is a view schematically showing a part of the electrolytic capacitor shown in Fig. 1. Fig. 5 is a top view schematically showing a part of the electrolytic capacitor shown in Fig. 1. Fig. 6 is a top view schematically showing an example of a first lead terminal used in the electrolytic capacitor shown in Fig. 1.

[0010] The following describes embodiments of the present disclosure using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and other materials may be applied as long as the effects of the present disclosure are obtained. In this specification, the term "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "numerical value A or greater and numerical value B or less." In the following description, when lower and upper limits for specific physical properties or conditions are exemplified, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined, as long as the lower limit is not greater than the upper limit. In the following description, when examples of components are listed, only one of the listed examples may be used, or multiple of the listed examples may be used in combination, unless otherwise specified.

[0011] (Electrolytic Capacitor) Hereinafter, the electrolytic capacitor according to this embodiment may be referred to as an "electrolytic capacitor (C)" or a "capacitor (C)." The capacitor (C) includes at least one capacitor element, a first lead terminal and a second lead terminal connected to the at least one capacitor element, and an exterior body covering a portion of the first lead terminal, a portion of the second lead terminal, and the at least one capacitor element. The first lead terminal includes an embedded portion embedded in the exterior body and an exposed portion exposed from the exterior body. The first lead terminal has two main surfaces and a lead side surface Ls connecting the two main surfaces. The exterior body has a first end surface Pe1 from which the exposed portion of the first lead terminal protrudes, and a second end surface Pe2 opposite the first end surface Pe1. The embedded portion includes a protruding portion protruding from the lead side surface Ls.

[0012] The protrusion may protrude toward the surface of the exterior body. Preferably, the protrusion is not exposed from the exterior body. By not having the protrusion exposed from the exterior body, water or oxygen can be prevented from entering through the interface between the protrusion and the exterior body.

[0013] Electrolytic capacitors are required to have a long life, especially in high-temperature environments. The capacitor element is covered by an exterior case. However, if the airtightness of the exterior case decreases, the capacitor element will deteriorate due to the intrusion of water or oxygen from the outside, resulting in an increase in equivalent series resistance (ESR). Therefore, maintaining the airtightness of the exterior case is important to suppress the deterioration of electrolytic capacitors.

[0014] One of the factors that can reduce the airtightness of an exterior body is a decrease in adhesion between the lead terminals and the exterior body. For example, when assembling an electrolytic capacitor, tensile stress is applied to the lead terminals, which can reduce the adhesion between the lead terminals and the exterior body. Furthermore, when an electrolytic capacitor is heated during the reflow process when mounting the electrolytic capacitor on a substrate, moisture inside the electrolytic capacitor expands, which can reduce the adhesion between the lead terminals and the exterior body. Furthermore, temperature changes during use of an electrolytic capacitor can reduce the adhesion between the lead terminals and the exterior body.

[0015] As a result of investigation, the inventors of the present application have found that the deterioration of adhesion between the lead terminal and the outer casing can be suppressed by changing the shape of the lead terminal. The present disclosure is based on this new finding.

[0016] The embedded portion of the lead terminal of the capacitor (C) has a protrusion. This protrusion makes it less likely that misalignment will occur between the exterior body and the lead terminal. As a result, adhesion between the exterior body and the lead terminal is improved. Furthermore, even if stress occurs during the manufacturing of the electrolytic capacitor or due to temperature changes, the anchoring effect of the protrusion can prevent a decrease in adhesion between the lead terminal and the exterior body. Furthermore, the side surface of the lead terminal of the capacitor (C) is longer by the length of the protrusion. As a result, moisture and oxygen can be prevented from reaching the capacitor element through the interface between the side surface of the lead terminal and the exterior body. In this way, the configuration of the capacitor (C) can prevent deterioration.

[0017] The number N of capacitor elements included in the capacitor (C) is not particularly limited. The number N of capacitor elements included in the capacitor (C) may be 1, or may be 2 or more. The upper limit of the number N is not particularly limited, but may be 10 or less. When the capacitor (C) includes multiple capacitor elements, the multiple capacitor elements may be stacked so as to be connected in parallel.

[0018] The embedded portion may include a connection portion that is directly or indirectly connected to at least one capacitor element, and a lead portion that connects the connection portion to the exposed portion. The protrusion may protrude from a lead side surface Ls of the lead portion.

[0019] The connection part is directly or indirectly connected to the capacitor element. An example in which the connection part is directly connected to the capacitor element includes a configuration in which the connection part is connected to a part of the capacitor element by welding or the like. An example in which the connection part is indirectly connected to the capacitor element includes a configuration in which the connection part is connected to the capacitor element via a conductive layer. Examples of the conductive layer include a carbon layer, a metal particle layer (e.g., a silver particle layer), etc.

[0020] The lead side surface Ls includes a first lead side surface Ls1 and a second lead side surface Ls2. The protrusion may include a first protrusion protruding from the first lead side surface Ls1 and a second protrusion protruding from the second lead side surface Ls2. When the embedded portion has two protrusions, the adhesion between the exterior body and the lead terminal is particularly improved. The first protrusion and the second protrusion may protrude symmetrically. Note that the lead side surface Ls on the side of the first side surface Ps1 (described later) can be referred to as the first lead side surface Ls1, and the lead side surface Ls on the side of the second side surface Ps2 (described later) can be referred to as the second lead side surface Ls2.

[0021] The exposed portion may include a terminal portion connected to an external circuit. The exterior body may have a first end face Pe1, a second end face Pe2, a bottom face on which the terminal portion is located, an upper face opposite the bottom face, and a first side face Ps1 and a second side face Ps2 connecting the first end face Pe1 and the second end face Pe2. In this case, the exterior body may have a generally rectangular parallelepiped shape. The first protrusion may protrude toward the first side face Ps1, and the second protrusion may protrude toward the second side face Ps2. This configuration does not require processing to bend the protrusions. Furthermore, this configuration makes it easy to ensure a distance between the top and bottom faces of the exterior body and the protrusions.

[0022] The planar shape of the protrusion (the shape of the main surface of the protrusion) is not particularly limited, and may be rectangular, triangular, trapezoidal, or any other shape.

[0023] The protrusion has two main surfaces and a side surface Xs connecting the two main surfaces. The side surface Xs may have a first side surface Xs1 on the first end surface Pe1 side and a second side surface Xs2 on the second end surface Pe2 side.

[0024] The distance between the first side surface Xs1 and the first end face Pe1 may increase with increasing distance from the lead side surface Ls adjacent to the protrusion (more specifically, the first side surface Xs1 of the protrusion). This configuration can prevent cracks from occurring between the first side surface Xs1 and the first end face Pe1. In this case, the distance between the first side surface Xs1 and the first end face Pe1 may increase continuously with increasing distance from the lead side surface Ls adjacent to the protrusion. Alternatively, the distance between the first side surface Xs1 and the first end face Pe1 may increase in a stepwise manner with increasing distance from the lead side surface Ls adjacent to the protrusion.

[0025] The angle α1 formed between the lead side surface Ls adjacent to the protrusion (more specifically, the first side surface Xs1 of the protrusion) and the first side surface Xs1 may be 160° or less, or 140° or less. By setting the angle α1 to 160° or less, the anchoring effect of the protrusion can be particularly enhanced.

[0026] The angle α1 may be equal to or greater than 90°, equal to or greater than 130°, or equal to or greater than 150°. By setting the angle α1 to 130° or greater, it is possible to particularly prevent cracks from occurring in the exterior body between the first side surface Xs1 and the first end face Pe1 and to prevent peeling between the exterior body and the first lead terminal. When the angle α1 is greater than 90°, the distance between the first side surface Xs1 and the first end face Pe1 increases with increasing distance from the lead side surface Ls adjacent to the protrusion.

[0027] The angle β1 formed between the lead side surface Ls adjacent to the protrusion (more specifically, the second side surface Xs2 of the protrusion) and the second side surface Xs2 may be 90° or less, or 70° or less. By setting the angle β1 to 90° or less, a high anchor effect is obtained. As a result, the adhesion between the exterior body and the lead terminal is improved. The angle β1 may be 90°.

[0028] The distance between the second side surface Xs2 and the first end face Pe1 may increase with increasing distance from the lead side surface Ls adjacent to the protrusion (more specifically, the second side surface Xs2 of the protrusion). This configuration provides a particularly high anchor effect. In this case, the distance between the second side surface Xs2 and the first end face Pe1 may increase continuously with increasing distance from the lead side surface Ls adjacent to the protrusion. Alternatively, the distance between the second side surface Xs2 and the first end face Pe1 may increase in a stepwise manner with increasing distance from the lead side surface Ls adjacent to the protrusion.

[0029] The angle β1 may be equal to or greater than 60°, or equal to or greater than 80°. By setting the angle β1 to be equal to or greater than 60°, formation by punching becomes easier.

[0030] The thermal expansion coefficient of the exterior body at 110°C may be smaller than the thermal expansion coefficient of the first lead terminal at 110°C. This configuration can suppress a decrease in adhesion between the exterior body and the lead terminal due to temperature changes. Similarly, the thermal expansion coefficient of the exterior body at 110°C may be smaller than the thermal expansion coefficient of the second lead terminal (described later) at 110°C. The thermal expansion coefficient of the exterior body can be changed by the type of material (resin, inorganic filler, etc.) constituting the exterior body. The thermal expansion coefficient of the lead terminal can be changed by the type of metal constituting the lead terminal. Note that the thermal expansion coefficient of the exterior body at 110°C may be equal to or greater than the thermal expansion coefficient of the lead terminals (first lead terminal, second lead terminal) at 110°C. In this specification, thermal expansion coefficient means the linear thermal expansion coefficient.

[0031] The second lead terminal may include an embedded portion embedded in the outer casing and an exposed portion exposed from the outer casing. The exposed portion of the second lead terminal may protrude from the second end face Pe2. The second lead terminal may have two main surfaces and a lead side surface Ls connecting the two main surfaces.

[0032] The embedded portion of the second lead terminal may include a protruding portion protruding from the lead side surface of the second lead terminal. That is, the second lead terminal may have a protruding portion similar to that of the first lead terminal. The matters described above regarding the protruding portion of the first lead terminal can also be applied to the protruding portion of the second lead terminal, and therefore, redundant description will be omitted. However, when the matters described above regarding the shape of the protruding portion of the first lead terminal are applied to the second lead terminal, the first end face Pe1 should be read as the second end face Pe2, and the second end face Pe2 should be read as the first end face Pe1. The shape of the protruding portion of the first lead terminal and the shape of the protruding portion of the second lead terminal may be the same or different.

[0033] The embedded portion of the second lead terminal may include a connection portion connected directly or indirectly to at least one capacitor element, and a lead portion connecting the connection portion and the exposed portion. The protruding portion of the second lead terminal may protrude from a lead side surface Ls of the lead portion of the second lead terminal.

[0034] The lead side surface Ls of the second lead terminal may include a first lead side surface Ls1 and a second lead side surface Ls2. The protruding portion of the second lead terminal may include a first protruding portion protruding from the first lead side surface Ls1 of the second lead terminal and a second protruding portion protruding from the second lead side surface Ls2 of the second lead terminal.

[0035] The exposed portion of the second lead terminal may include a terminal portion to be connected to an external circuit. The exterior body may have a first end face Pe1, a second end face Pe2, a bottom face on which the terminal portion is located, a top face opposite the bottom face, and a first side face Ps1 and a second side face Ps2 connecting the first end face Pe1 and the second end face Pe2. The first protrusion of the second lead terminal may protrude toward the first side face Ps1. The second protrusion of the second lead terminal may protrude toward the second side face Ps2.

[0036] The projection of the second lead terminal may have a triangular planar shape.

[0037] The protruding portion of the second lead terminal may have two main surfaces and a side surface Xs connecting the two main surfaces. The side surface Xs of the second lead terminal may have a first side surface Xs1 on the second end surface Pe2 side and a second side surface Xs2 on the first end surface Pe1 side.

[0038] The distance between the first side surface Xs1 of the second lead terminal and the second end face Pe2 may increase as the distance increases from the lead side surface Ls of the second lead terminal adjacent to the protrusion (more specifically, the first side surface Xs1 of the protrusion) of the second lead terminal.

[0039] The angle α2 formed between the lead side surface Ls of the second lead terminal adjacent to the protrusion (more specifically, the first side surface Xs1 of the protrusion) of the second lead terminal and the first side surface Xs1 of the second lead terminal may be 160° or less. Similar to the angle α1, the angle α2 may be 90° or more, 130° or more, or 150° or more.

[0040] The angle β2 formed between the lead side surface Ls of the second lead terminal adjacent to the protrusion (more specifically, the second side surface Xs2 of the protrusion) of the second lead terminal and the second side surface Xs2 of the second lead terminal may be 90° or less.

[0041] The angle β2 of the second lead terminal may be 60° or more.

[0042] The thermal expansion coefficient of the outer casing at 110°C may be smaller than the thermal expansion coefficient of the second lead terminal at 110°C.

[0043] Examples of components of the electrolytic capacitor of the present disclosure are described below, but the configuration of the electrolytic capacitor (C) according to the present disclosure is not limited to the configuration exemplified below. Except for the parts unique to the electrolytic capacitor (C), components of the electrolytic capacitor (C) may be components used in known electrolytic capacitors (C).

[0044] The electrolytic capacitor (C) includes at least one capacitor element, lead terminals (anode lead terminal, cathode lead terminal), and an outer casing. The capacitor element includes an anode portion, a dielectric layer, and a cathode portion. The dielectric layer is formed on the surface of the anode portion. The anode lead terminal is connected to the anode portion. The cathode lead terminal is connected to the cathode portion.

[0045] One of the anode lead terminal and the cathode lead terminal is a first lead terminal, and the other is a second lead terminal. The protrusion may be formed only on the anode lead terminal, or only on the cathode lead terminal. Alternatively, the protrusion may be formed on both the anode lead terminal and the cathode lead terminal.

[0046] (Anode part) The anode part includes an anode body. The anode body may be a foil (metal foil) containing a valve metal. Examples of valve metals include titanium, tantalum, aluminum, and niobium. The anode body may be an aluminum foil. The thickness of the anode body is not particularly limited. The thickness of the anode body may be in the range of 15 to 300 μm (for example, in the range of 80 to 250 μm).

[0047] At least a portion of the surface of the anode body (for example, aluminum foil) may be roughened by electrolytic etching or the like. In this case, the anode body has a porous portion on its surface.

[0048] (Dielectric Layer) The dielectric layer is formed on at least a portion of the surface of the anode body. The dielectric layer may be formed by anodizing the surface of the anode body (e.g., anodizing by chemical conversion treatment). In this case, the dielectric layer contains an oxide of a valve metal. For example, when an aluminum foil is used as the anode body, an aluminum oxide layer (dielectric layer) is formed on the surface of the aluminum foil by anodizing the aluminum foil.

[0049] (Cathode part) The cathode part includes an electrolyte layer (solid electrolyte layer) and a cathode extraction layer adjacent to the electrolyte layer. The cathode extraction layer may be formed so as to cover at least a part of the electrolyte layer, or may be formed so as to cover the entire surface of the electrolyte layer.

[0050] The electrolyte layer (solid electrolyte layer) is disposed so as to cover at least a portion of the dielectric layer, or may be disposed so as to cover the entire surface of the dielectric layer.

[0051] The electrolyte layer can be formed from a manganese compound, a conductive polymer, or the like. Examples of the conductive polymer include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polythiophene vinylene, and derivatives thereof. A preferred example of the conductive polymer is poly(3,4-ethylenedioxythiophene).

[0052] The conductive polymer may be doped with a dopant. The dopant may be a polymer dopant. Examples of polymer dopants include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallylsulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and polyacrylic acid. A preferred example of the dopant is polystyrene sulfonic acid (PSS). A preferred example of the electrolyte layer is formed using poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonic acid (PSS).

[0053] The electrolyte layer containing a conductive polymer may be formed by a known method. The electrolyte layer may be formed by contacting the anode body on which the dielectric layer has been formed with a solution or dispersion of the conductive polymer and then drying the anode body. Alternatively, the electrolyte layer may be formed on the surface of the dielectric layer by chemical polymerization or electrolytic polymerization.

[0054] The cathode extraction layer may be a conductive layer. Examples of conductive layers include a carbon layer and a metal-containing layer. The metal-containing layer may be a metal particle layer containing metal particles (e.g., a silver particle layer). The metal particle layer may be formed from a metal paste (e.g., a silver paste). The cathode extraction layer may be composed of multiple layers. For example, the cathode extraction layer may include a carbon layer formed on an electrolyte layer and a metal particle layer (e.g., a silver particle layer) formed on the carbon layer. The cathode extraction layer may be formed by a known method. For example, a material for the cathode extraction layer may be applied, followed by drying and / or heat treatment as necessary.

[0055] (Exterior Body) The exterior body includes an exterior resin. Examples of the exterior resin include curable resins and engineering plastics. Examples of the curable resins (e.g., thermosetting resins) include epoxy resins, phenolic resins, silicone resins, melamine resins, urea resins, alkyd resins, polyurethanes, and unsaturated polyesters. Examples of the engineering plastics include general-purpose engineering plastics and super engineering plastics. Examples of the engineering plastics include polyimides and polyamideimides.

[0056] In addition to the exterior resin, the exterior body may contain other additives such as inorganic fillers. That is, at least a portion of the exterior body may be composed of a resin composition. Examples of inorganic fillers include silica (e.g., fused silica), talc, calcium carbonate, and aluminum oxide.

[0057] (Lead Terminals) As described above, a given lead terminal has a protrusion. The first lead terminal and the second lead terminal may each be formed by processing a single metal sheet. That is, the protrusion and the lead portion can be formed integrally. The material of the lead terminals (anode lead terminal and cathode lead terminal) is not particularly limited as long as it is electrochemically and chemically stable and conductive. The lead terminals are usually made of metal (e.g., iron alloy, copper, copper alloy, etc.). The surfaces of the lead terminals may be plated. The thickness of the lead terminals may be in the range of 25 μm to 200 μm (e.g., in the range of 25 μm to 100 μm).

[0058] (Example of Manufacturing Method of Electrolytic Capacitor) There are no particular limitations on the manufacturing method of the electrolytic capacitor according to this embodiment. A known manufacturing method may be applied, or a known manufacturing method may be partially modified depending on the configuration of the electrolytic capacitor according to this embodiment.

[0059] In one example manufacturing method, anode lead terminals and cathode lead terminals are first formed by punching a metal sheet. At this time, punching is performed so that protrusions are formed on selected lead terminals. Next, the lead terminals are bent into a predetermined shape. Next, the connection portions of the anode lead terminal and the cathode lead terminal are connected to the capacitor element, respectively. The connection may be performed by welding or via a conductive layer. Next, a portion of the lead terminals and the capacitor element are sealed with an exterior body. Sealing with the exterior body may be performed by transfer molding or the like. Next, exposed portions of the lead terminals are cut or bent as necessary. In this manner, an electrolytic capacitor is manufactured.

[0060] 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 embodiments. In the embodiments described below, components that are not essential to the electrolytic capacitor of the present disclosure may be omitted. Note that in order to make the drawings easier to understand, some components may be omitted in the following figures. In addition, in the following figures, the scale of some components may be changed to make the illustration easier.

[0061] (Embodiment 1) Fig. 1 is a cross-sectional view schematically illustrating an electrolytic capacitor 10 according to Embodiment 1. Fig. 2 is a top view schematically illustrating the electrolytic capacitor 10. In Embodiment 1, an example will be described in which the first lead terminal is an anode lead terminal and the second lead terminal is a cathode lead terminal. As described above, the first lead terminal may be a cathode lead terminal and the second lead terminal may be an anode lead terminal. In Embodiment 1, an example will be described in which both the first lead terminal and the second lead terminal have protrusions.

[0062] The electrolytic capacitor 10 includes four capacitor elements 100, a first lead terminal (anode lead terminal) 20, a second lead terminal (cathode lead terminal) 30, and an exterior housing 40. The anode portions 110 of the four capacitor elements 100 are connected together to the first lead terminal 20. The cathode portions 130 of the four capacitor elements 100 are connected to each other and further to the second lead terminal 30 via a conductive layer 51. Note that, for clarity, the dielectric layer is omitted from FIG. 1 . The exterior housing 40 encapsulates a portion of the first lead terminal 20, a portion of the second lead terminal 30, and the capacitor elements 100.

[0063] The four capacitor elements 100 are stacked in a direction connecting the bottom surface 40Pb and the top surface 40Pt of the exterior body 40. The cathode portions 130 of the four capacitor elements 100 may be connected to each other by a conductive layer or the like. The anode portions 110 of the four capacitor elements 100 may be connected to each other by welding or the like.

[0064] The first lead terminal 20 is formed from a single metal sheet. The first lead terminal 20 includes an embedded portion 21 embedded in the exterior body 40 and an exposed portion 22 exposed from the exterior body 40. The embedded portion 21 includes a connection portion 21a directly or indirectly connected to the anode portion 110 (capacitor element 100) and a lead portion 21b connecting the connection portion 21a and the exposed portion 22. The exposed portion 22 includes a terminal portion 22a connected to an external circuit and an exposed lead portion 22b connecting the terminal portion 22a and the embedded portion 21. The terminal portion 22a is the portion connected to the external circuit. For example, the terminal portion 22a may be soldered to a circuit board. The connection portion 21a may include two wing portions arranged to surround the side surfaces of the end portion of the anode portion 110. The embedded portion 21 includes two protrusions 21X protruding toward the surface of the exterior body 40.

[0065] The second lead terminal 30 is formed from a single metal sheet. The second lead terminal 30 includes an embedded portion 31 embedded in the exterior body 40 and an exposed portion 32 exposed from the exterior body 40. The embedded portion 31 includes a connection portion 31a indirectly connected to the cathode portion 130 (capacitor element 100) via a conductive layer 51, and a lead portion 31b connecting the connection portion 31a and the exposed portion 32. The exposed portion 32 includes a terminal portion 32a connected to an external circuit and an exposed lead portion 32b connecting the terminal portion 32a and the embedded portion 31. The terminal portion 32a is a portion where soldering or the like is performed. The connection portion 31a may include two wing portions arranged to surround the side surfaces of the cathode portion 130. The embedded portion 31 includes two protrusions 31X protruding toward the surface of the exterior body 40.

[0066] The exterior body 40 has a rectangular parallelepiped shape. Referring to FIGS. 1 and 2 , the exterior body 40 has a first end face 40Pe1, a second end face 40Pe2, a bottom face 40Pb, a top face 40Pt, a first side face 40Ps1, and a second side face 40Ps2. The first end face 40Pe1 is the face from which the first lead terminal 20 protrudes. The second end face 40Pe2 is the face from which the second lead terminal 30 protrudes. The bottom face 40Pb is the face on which the terminal portions 22a and 32a are disposed. The first side face 40Ps1 and the second side face 40Ps2 are faces that connect the first end face 40Pe1 and the second end face 40Pe2, and also connect the bottom face 40Pb and the top face 40Pt.

[0067] 3 is a schematic cross-sectional view of an example of a capacitor element 100. The capacitor element 100 includes an anode portion (anode body) 110, a dielectric layer 120 covering at least a portion of the anode portion 110, and a cathode portion 130 covering at least a portion of the dielectric layer 120. The cathode portion 130 includes a solid electrolyte layer 131 covering at least a portion of the dielectric layer 120, and a cathode extraction layer 132 formed on the solid electrolyte layer 131. The cathode extraction layer 132 includes a carbon layer 132a and a silver particle layer 132b stacked in this order from the solid electrolyte layer 131 side.

[0068] An enlarged view of the embedded portion 21 of the first lead terminal 20 is shown in Fig. 4. A top view of the portion shown in Fig. 4 is shown in Fig. 5. Furthermore, a top view of the first lead terminal 20 shown in Fig. 5 is shown in Fig. 6. Fig. 5 shows the direction LD connecting the first end face 40Pe1 and the second end face 40Pe2, and the direction WD connecting the first side face 40Ps1 and the second side face 40Ps2.

[0069] 4, the first lead terminal 20 has main surfaces 20Lp1 and 20Lp2 and a lead side surface 20Ls connecting the two main surfaces. With reference to FIGS. 5 and 6, the lead side surface 20Ls includes a first lead side surface 20Ls1 on the first side surface 40Ps1 side of the exterior body 40 and a second lead side surface 20Ls2 on the second side surface 40Ps2 side of the exterior body 40.

[0070] The first lead terminal 20 has two protrusions 21X that protrude from the lead side surface 20Ls toward the surface of the exterior body 40. Specifically, the first lead terminal 20 has a first protrusion 21X1 that protrudes toward the first side surface 40Ps1 of the exterior body 40 and a second protrusion 21X2 that protrudes toward the second side surface 40Ps2 of the exterior body 40. The first protrusion 21X1 protrudes from the first lead side surface 20Ls1 of the first lead terminal 20. The second protrusion 21X2 protrudes from the second lead side surface 20Ls2 of the first lead terminal 20. The protrusions 21X are usually not bent.

[0071] 6, each protrusion 21X has two main surfaces 21Xp and a side surface 21Xs connecting the two main surfaces 21Xp. Note that another main surface 21Xp exists on the opposite side of the main surface 21Xp on the upper surface side shown in FIG. 6. The side surface 21Xs has a first side surface 21Xs1 on the first end face 40Pe1 side and a second side surface 21Xs2 on the second end face 40Pe2 side.

[0072] In the example shown in FIG. 6 , the first side surface 21Xs1 is inclined so that the distance from the first end face Pe1 increases with increasing distance from the lead side surface 20Ls adjacent to the protrusion 21X. The angle α1 formed between the first side surface 21Xs1 and the lead side surface 20Ls adjacent to the protrusion 21X may be within the above-mentioned range. The angle α1' formed between a plane parallel to the first end face 40Pe1 and a plane including the first side surface 21Xs1 is expressed as (α1-90°) (where α1 can be an angle within the above-mentioned range). In other words, the first side surface 21Xs1 is a plane inclined by (α1-90°) from the plane parallel to the first end face 40Pe1.

[0073] 6 shows an example in which the first side surface 21Xs1 extends from the boundary between the embedded portion 21 and the exposed portion 22. However, the first side surface 21Xs1 of the protruding portion 21X may protrude from the lead side surface 20Ls inside the exterior body 40.

[0074] In the example shown in Figure 6, the second side surface 21Xs2 is inclined so that the distance from the first end face Pe1 increases as the protrusion 21X moves away from the adjacent lead side surface 20Ls. The angle β1 formed between the lead side surface 20Ls and the second side surface 21Xs2 may be within the above-mentioned range. The angle β1' formed between the second side surface 21Xs2 and a plane parallel to the first end face 40Pe1 is expressed as (90° - β1) (here, β1 can be an angle within the above-mentioned range). In other words, the second side surface 21Xs2 is a plane inclined by (90° - β1) from a plane parallel to the first end face 40Pe1.

[0075] The protrusion 31X may have the same shape as or a different shape from the protrusion 21X. The lead terminal of the electrolytic capacitor 10 has a protrusion, and therefore the above-described effects can be obtained.

[0076] (Additional Notes) The above description discloses the following techniques: (Technology 1) An electrolytic capacitor including: at least one capacitor element; a first lead terminal and a second lead terminal connected to the at least one capacitor element; and an exterior body covering a portion of the first lead terminal, a portion of the second lead terminal, and the at least one capacitor element, wherein the first lead terminal includes an embedded portion embedded in the exterior body and an exposed portion exposed from the exterior body, the first lead terminal has two main surfaces and a lead side surface Ls connecting the two main surfaces, the exterior body has a first end surface Pe1 from which the exposed portion of the first lead terminal protrudes and a second end surface Pe2 opposite the first end surface Pe1, and the embedded portion includes a protruding portion protruding from the lead side surface Ls. (Technology 2) The electrolytic capacitor according to Technology 1, wherein the embedded portion includes a connection portion directly or indirectly connected to the at least one capacitor element and a lead portion connecting the connection portion and the exposed portion, and the protrusion protrudes from the lead side surface Ls of the lead portion. (Technology 3) The electrolytic capacitor according to Technology 1 or 2, wherein the lead side surface Ls includes a first lead side surface Ls1 and a second lead side surface Ls2, and the protrusion includes a first protrusion protruding from the first lead side surface Ls1 and a second protrusion protruding from the second lead side surface Ls2. (Technology 4) The electrolytic capacitor according to Technology 3, wherein the exposed portion includes a terminal portion to be connected to an external circuit, the exterior body has the first end face Pe1, the second end face Pe2, a bottom face on which the terminal portion is arranged, an upper face opposite the bottom face, and a first side face Ps1 and a second side face Ps2 connecting the first end face Pe1 and the second end face Pe2, the first protrusion protrudes toward the first side face Ps1, and the second protrusion protrudes toward the second side face Ps2. (Technology 5) The electrolytic capacitor according to any one of Technology 1 to 4, wherein the planar shape of the protrusion is triangular.(Technology 6) The electrolytic capacitor according to any one of Techniques 1 to 5, wherein the protrusion has two main surfaces and a side surface Xs connecting the two main surfaces, the side surface Xs having a first side surface Xs1 on the first end face Pe1 side and a second side surface Xs2 on the second end face Pe2 side. (Technology 7) The electrolytic capacitor according to Technique 6, wherein the distance between the first side surface Xs1 and the first end face Pe1 increases with increasing distance from the lead side surface Ls adjacent to the protrusion. (Technology 8) The electrolytic capacitor according to Technique 6 or 7, wherein the angle α1 formed between the lead side surface Ls adjacent to the protrusion and the first side surface Xs1 is 160° or less. (Technology 9) The electrolytic capacitor according to any one of Techniques 6 to 8, wherein the angle β1 formed between the lead side surface Ls adjacent to the protrusion and the second side surface Xs2 is 90° or less. (Technology 10) The electrolytic capacitor according to Technique 9, wherein the angle β1 is 60° or more. (Technology 11) The electrolytic capacitor according to any one of Technologies 1 to 10, wherein the thermal expansion coefficient of the exterior body at 110° C. is smaller than the thermal expansion coefficient of the first lead terminal at 110° C. (Technology 12) The electrolytic capacitor according to any one of Technologies 1 to 11, wherein the second lead terminal includes an embedded portion embedded in the exterior body and an exposed portion exposed from the exterior body, the exposed portion of the second lead terminal protrudes from the second end face Pe2, the second lead terminal has two main surfaces and a lead side surface Ls connecting the two main surfaces, and the embedded portion of the second lead terminal includes a protruding portion protruding from the lead side surface Ls of the second lead terminal. (Technology 13) An electrolytic capacitor according to Technology 12, wherein the embedded portion of the second lead terminal includes a connection portion that is directly or indirectly connected to the at least one capacitor element and a lead portion that connects the connection portion and the exposed portion, and the protrusion portion of the second lead terminal protrudes from the lead side surface Ls of the lead portion of the second lead terminal.(Technology 14) An electrolytic capacitor according to Technology 12 or 13, wherein the lead side surface Ls of the second lead terminal includes a first lead side surface Ls1 and a second lead side surface Ls2, and the protrusion of the second lead terminal includes a first protrusion protruding from the first lead side surface Ls1 of the second lead terminal and a second protrusion protruding from the second lead side surface Ls2 of the second lead terminal. (Technology 15) The electrolytic capacitor according to Technology 14, wherein the exposed portion of the second lead terminal includes a terminal portion connected to an external circuit, the exterior body has the first end face Pe1, the second end face Pe2, a bottom face on which the terminal portion is arranged, an upper face opposite the bottom face, and a first side face Ps1 and a second side face Ps2 connecting the first end face Pe1 and the second end face Pe2, the first protrusion of the second lead terminal protruding toward the first side face Ps1, and the second protrusion of the second lead terminal protruding toward the second side face Ps2. (Technology 16) The electrolytic capacitor according to any one of Technology 12 to 15, wherein the planar shape of the protrusion of the second lead terminal is triangular. (Technology 17) The electrolytic capacitor according to any one of Techniques 12 to 16, wherein the protruding portion of the second lead terminal has two main surfaces and a side surface Xs connecting the two main surfaces, and the side surface Xs of the second lead terminal has a first side surface Xs1 on the second end face Pe2 side and a second side surface Xs2 on the first end face Pe1 side. (Technology 18) The electrolytic capacitor according to Technique 17, wherein the distance between the first side surface Xs1 of the second lead terminal and the second end face Pe2 increases with increasing distance from the lead side surface Ls of the second lead terminal adjacent to the protruding portion of the second lead terminal. (Technology 19) The electrolytic capacitor according to Techniques 17 or 18, wherein the angle α2 formed between the lead side surface Ls of the second lead terminal adjacent to the protruding portion of the second lead terminal and the first side surface Xs1 of the second lead terminal is 160° or less.(Technology 20) The electrolytic capacitor according to any one of Technologies 17 to 19, wherein the angle β2 formed between the lead side surface Ls of the second lead terminal adjacent to the protruding portion of the second lead terminal and the second side surface Xs2 of the second lead terminal is 90° or less. (Technology 21) The electrolytic capacitor according to Technology 20, wherein the angle β2 of the second lead terminal is 60° or more. (Technology 22) The electrolytic capacitor according to any one of Technologies 12 to 21, wherein the thermal expansion coefficient of the exterior body at 110°C is smaller than the thermal expansion coefficient of the second lead terminal at 110°C.

[0077] The present disclosure is applicable to electrolytic capacitors. Although the present invention has been described with reference to presently preferred embodiments, such disclosure should not be construed as limiting. Various modifications and alterations will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. Therefore, the appended claims should be construed to cover all modifications and alterations without departing from the true spirit and scope of the present invention.

[0078] 10: Electrolytic capacitor 20: First lead terminal 20Ls: Lead side surface 20Ls1: First lead side surface 20Ls2: Second lead side surface 21: Embedded portion 21a, 31a: Connection portion 21b, 31b: Lead portion 21X, 31X: Protruding portion 21X1: First protruding portion 21X2: Second protruding portion 21Xs1: First side surface 21Xs2: Second side surface 22, 32: Exposed portion 22a, 32a: Terminal portion 30: Second lead terminal 40: Outer casing 40Pb: Bottom surface 40Pe1: First end surface 40Pe2: Second end surface 40Ps1: First side surface 40Ps2: Second side surface 40Pt : Upper surface 100: Capacitor element

Claims

1. An electrolytic capacitor comprising: at least one capacitor element; a first lead terminal and a second lead terminal connected to the at least one capacitor element; and an exterior body covering a portion of the first lead terminal, a portion of the second lead terminal, and the at least one capacitor element, wherein the first lead terminal includes an embedded portion embedded in the exterior body and an exposed portion exposed from the exterior body, the first lead terminal having two main surfaces and a lead side surface Ls connecting the two main surfaces, the exterior body having a first end surface Pe1 from which the exposed portion of the first lead terminal protrudes, and a second end surface Pe2 opposite the first end surface Pe1, and the embedded portion includes a protruding portion protruding from the lead side surface Ls.

2. The electrolytic capacitor according to claim 1, wherein the embedded portion includes a connection portion that is directly or indirectly connected to the at least one capacitor element, and a lead portion that connects the connection portion to the exposed portion, and the protrusion protrudes from the lead side surface Ls of the lead portion.

3. An electrolytic capacitor as described in claim 1, wherein the lead side surface Ls includes a first lead side surface Ls1 and a second lead side surface Ls2, and the protrusion includes a first protrusion protruding from the first lead side surface Ls1 and a second protrusion protruding from the second lead side surface Ls2.

4. The electrolytic capacitor described in claim 3, wherein the exposed portion includes a terminal portion to be connected to an external circuit, the outer casing has the first end face Pe1, the second end face Pe2, a bottom surface on which the terminal portion is located, an upper surface opposite the bottom surface, and a first side face Ps1 and a second side face Ps2 connecting the first end face Pe1 and the second end face Pe2, the first protrusion protruding toward the first side face Ps1, and the second protrusion protruding toward the second side face Ps2.

5. The electrolytic capacitor according to claim 1, wherein the planar shape of said protrusion is triangular.

6. The electrolytic capacitor according to any one of claims 1 to 5, wherein the protrusion has two main surfaces and a side surface Xs connecting the two main surfaces, and the side surface Xs has a first side surface Xs1 on the side of the first end face Pe1 and a second side surface Xs2 on the side of the second end face Pe2.

7. The electrolytic capacitor according to claim 6, wherein the distance between the first side surface Xs1 and the first end surface Pe1 increases with increasing distance from the lead side surface Ls adjacent to the protrusion.

8. The electrolytic capacitor according to claim 7, wherein the angle α1 formed between the lead side surface Ls adjacent to the protrusion and the first side surface Xs1 is 160° or less.

9. The electrolytic capacitor according to claim 6, wherein the angle β1 formed between the lead side surface Ls adjacent to the protrusion and the second side surface Xs2 is 90° or less.

10. The electrolytic capacitor according to claim 9, wherein the angle β1 is equal to or greater than 60°.

11. The electrolytic capacitor according to any one of claims 1 to 5, wherein the thermal expansion coefficient of the outer casing at 110°C is smaller than the thermal expansion coefficient of the first lead terminal at 110°C.

12. The electrolytic capacitor of claim 1, wherein the second lead terminal includes an embedded portion embedded in the outer casing and an exposed portion exposed from the outer casing, the exposed portion of the second lead terminal protruding from the second end face Pe2, the second lead terminal has two main surfaces and a lead side surface Ls connecting the two main surfaces, and the embedded portion of the second lead terminal includes a protruding portion protruding from the lead side surface Ls of the second lead terminal.

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