Solid Electrolytic Capacitors

Abstract

To provide a solid electrolytic capacitor hardly causing changes in capacitor element characteristics.SOLUTION: A solid electrolytic capacitor 1 includes at least one capacitor element 2, an exterior resin 3, and a covering layer 6. The solid electrolytic capacitor includes an anode body 4 that includes a dielectric layer 41, and a solid electrolyte layer 5 that covers at least a part of the dielectric layer. The exterior resin covers a capacitor element. The covering layer is located between the capacitor element and the exterior resin, which contains at least a fluorine compound or has an oil repellency.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates generally to solid electrolytic capacitors, and more particularly to a solid electrolytic capacitor having an exterior resin that covers a capacitor element. [Background technology]

[0002] Patent Document 1 describes a solid electrolytic capacitor having a capacitor element, a barrier layer, and an exterior resin (resin exterior). The barrier layer is formed by sequentially laminating a coating layer, an inorganic layer and / or a metal layer formed by vapor phase growth on the capacitor element. The exterior resin covers the capacitor element and the barrier layer. In this solid electrolytic capacitor, the barrier layer prevents the intrusion of moisture and oxygen from the outside, stabilizing the characteristics. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-194310 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, the exterior resin covers the capacitor element together with the barrier layer, so if the exterior resin contains a wax component, the wax component may infiltrate the barrier layer and come into contact with the capacitor element. If the solid electrolytic capacitor is exposed to a high-temperature environment while the wax component is in contact with the capacitor element, the characteristics of the capacitor element may change due to the influence of the heated wax component.

[0005] The present disclosure has been made in view of the above-mentioned circumstances, and has an object to provide a solid electrolytic capacitor in which changes in the characteristics of the capacitor element are less likely to occur. [Means for solving the problem]

[0006] A solid electrolytic capacitor according to one embodiment of the present disclosure includes at least one capacitor element, an exterior resin, and a coating layer. The capacitor element includes an anode body including a dielectric layer, and a solid electrolyte layer covering at least a portion of the dielectric layer. The exterior resin covers the capacitor element. The coating layer is located between the capacitor element and the exterior resin, and contains a fluorine compound.

[0007] A solid electrolytic capacitor according to another embodiment of the present disclosure includes at least one capacitor element, an exterior resin, and a coating layer. The capacitor element includes an anode body including a dielectric layer, and a solid electrolyte layer covering at least a portion of the dielectric layer. The exterior resin covers the capacitor element. The coating layer is located between the capacitor element and the exterior resin, and has oil repellency. Effect of the Invention

[0008] The present disclosure has the advantage of being able to provide a solid electrolytic capacitor in which changes in the characteristics of the capacitor element are less likely to occur. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a configuration of a main part of the solid electrolytic capacitor according to the first embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing the configuration of the solid electrolytic capacitor. [Diagram 3] FIG. 3 is a schematic perspective view showing the configuration of the solid electrolytic capacitor. [Figure 4] FIG. 4A is an explanatory diagram showing a schematic representation of the wax component in the exterior resin of the above solid electrolytic capacitor, and FIG. 4B is an explanatory diagram showing a schematic representation of the wax component in the exterior resin of a solid electrolytic capacitor according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Embodiment 1) (1) Overview As shown in FIG. 2, a solid electrolytic capacitor 1 according to this embodiment has at least one capacitor element 2 and an exterior resin 3. As shown in FIG. 1, the capacitor element 2 has an anode body 4 and a solid electrolyte layer 5. The anode body 4 includes a dielectric layer 41. The solid electrolyte layer 5 covers at least a portion of the dielectric layer 41. The exterior resin 3 covers the capacitor element 2. FIG. 1 is a schematic cross-sectional view in which a region Z1 in FIG. 2 is enlarged.

[0011] In solid electrolytic capacitor 1 configured as described above, capacitor element 2 is covered with exterior resin 3, so that capacitor element 2 is less susceptible to the effects of external forces, temperature, humidity, and the like acting on solid electrolytic capacitor 1, thereby reducing changes in the characteristics of capacitor element 2. However, if exterior resin 3 contains oil such as wax component 300 (see FIG. 4A), the wax component 300 may affect the characteristics of capacitor element 2.

[0012] Therefore, the solid electrolytic capacitor 1 according to this embodiment further includes a coating layer 6 containing a fluorine compound. The coating layer 6 is located between the capacitor element 2 and the exterior resin 3. Here, it is sufficient that the coating layer 6 is located between the capacitor element 2 and the exterior resin 3, and it is not essential for the solid electrolytic capacitor 1 that the coating layer 6 covers the entire surface of the capacitor element 2 or that the entire surface of the coating layer 6 is covered by the exterior resin 3.

[0013] According to the above-mentioned configuration, the coating layer 6 located between the capacitor element 2 and the exterior resin 3 makes it difficult for oils such as the wax component 300 contained in the exterior resin 3 to come into contact with the capacitor element 2, compared to a configuration without the coating layer 6. In other words, the coating layer 6 containing a fluorine compound makes it difficult for oils such as the wax component 300 to infiltrate from the exterior resin 3 to the capacitor element 2. Therefore, for example, when the solid electrolytic capacitor 1 is exposed to a high-temperature environment, even if the oil in the exterior resin 3 is heated to a high temperature, the oil is unlikely to affect the capacitor element 2, and the characteristics of the capacitor element 2 are unlikely to change.

[0014] (2)Details The configuration of the solid electrolytic capacitor 1 according to this embodiment will be described in more detail below with reference to Figs. 1 to 3. In Fig. 3, the exterior resin 3 is indicated by an imaginary line (two-dot chain line). All of the drawings referred to below are schematic drawings, and the ratios of sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios.

[0015] The solid electrolytic capacitor 1 according to the present embodiment is used, for example, in the power supply line of a CPU (Central Processing Unit) in a server device, a computer device, a home game machine, etc. The solid electrolytic capacitor 1 is also used, for example, in the power supply line of an FPGA (Field-Programmable Gate Array) in a communication device, an industrial device, etc., and in the power supply line of a GPU (Graphics Processing Unit) in a graphic board, etc. However, the uses of the solid electrolytic capacitor 1 are not limited thereto, and the solid electrolytic capacitor 1 can be used in a wide variety of fields.

[0016] As shown in FIGS. 2 and 3, the solid electrolytic capacitor 1 further includes a terminal portion 7 in addition to at least one capacitor element 2, exterior resin 3, and coating layer 6. The terminal portion 7 includes a first terminal 71 for an anode and a second terminal 72 for a cathode. The capacitor element 2 further includes a cathode layer 8 in addition to an anode body 4 and a solid electrolyte layer 5. The cathode layer 8 is formed on the surface of the capacitor element 2 so as to cover at least a part of the solid electrolyte layer 5. The first terminal 71 is electrically connected to the anode side conductive portion 42 (see FIG. 1) of the anode body 4, and the second terminal 72 is electrically connected to the cathode side conductive portion 82 (see FIG. 1) of the cathode layer 8. This allows the anode body 4 (the anode side conductive portion 42) and the cathode layer 8 (the cathode side conductive portion 82) of the capacitor element 2 to be electrically connected to an external circuit via the first terminal 71 and the second terminal 72, respectively.

[0017] In this embodiment, the first terminal 71 and the second terminal 72 constituting the terminal portion 7 are made of a conductive metal plate (lead frame). Each of the first terminal 71 and the second terminal 72 is embedded in the exterior resin 3 so that at least a portion of the terminal is exposed from the surface of the exterior resin 3. In other words, the solid electrolytic capacitor 1 according to this embodiment is a chip component (chip capacitor) compatible with surface mounting technology in which the terminal portion 7 (first terminal 71 and second terminal 72) exposed from the surface of the exterior resin 3 is mechanically and electrically connected to a circuit board by soldering or the like.

[0018] Here, the solid electrolytic capacitor 1 according to the present embodiment includes a plurality of capacitor elements 2. The plurality of capacitor elements 2 are covered with one exterior resin 3 in a stacked state. Each of the plurality of capacitor elements 2 includes an anode body 4, a solid electrolyte layer 5, and a cathode layer 8. As shown in FIG. 3, each of the plurality of capacitor elements 2 is formed in a plate shape that is substantially rectangular when viewed from one side in the thickness direction. In this manner, the plurality of capacitor elements 2 each formed in a plate shape are stacked so as to overlap each other in the thickness direction. In the present disclosure, the direction in which the capacitor elements 2 are stacked is also referred to as the "stacking direction". As an example, in the present embodiment, the solid electrolytic capacitor 1 includes seven capacitor elements 2, and has a configuration in which the seven capacitor elements 2 are stacked so that the thickness direction of each of the seven capacitor elements 2 is the stacking direction.

[0019] That is, the solid electrolytic capacitor 1 has a structure (laminate) in which a plurality of capacitor elements 2 having the same configuration are stacked in a stacking direction, and each of the plurality of capacitor elements 2 constitutes a capacitor. The plurality of capacitor elements 2 are electrically connected in parallel between the first terminal 71 and the second terminal 72. This makes it possible to keep the electrical resistance value between the two terminals (the first terminal 71 and the second terminal 72) of the solid electrolytic capacitor 1 as a whole relatively low.

[0020] More specifically, as shown in FIG. 3, when each capacitor element 2 is viewed from one side in the thickness direction (stacking direction), an anode lead-out portion 91, an insulating portion 92, an exposed portion 51 (described later), and a cathode layer 8 are formed on the surface of each capacitor element 2 in this order from one end in the longitudinal direction (the right end in the example of FIG. 2). The anode lead-out portion 91, the insulating portion 92, and the exposed portion 51 are each formed in a strip shape. The anode lead-out portion 91 is a portion for connecting the first terminal 71, and is configured by exposing a part of the anode-side conductive portion 42 from the dielectric layer 41. That is, the first terminal 71 is connected to the anode lead-out portion 91, whereby the first terminal 71 and the anode-side conductive portion 42 of the anode body 4 are electrically connected to each other. In addition, a second terminal 72 is connected to the cathode layer 8.

[0021] Furthermore, in this embodiment, the solid electrolyte layer 5 in the capacitor element 2 contains a conductive polymer. Examples of the conductive polymer include PPy (polypyrrole), PEDOT (polyethylenedioxythiophene), polyaniline, etc. In other words, the solid electrolytic capacitor 1 according to this embodiment employs a conductive polymer as the solid electrolyte, instead of manganese dioxide, etc.

[0022] The solid electrolytic capacitor 1 having the above-described configuration can keep the equivalent series resistance (ESR) low, and can achieve excellent low ESR performance.

[0023] The anode body 4, solid electrolyte layer 5, and cathode layer 8 constituting each capacitor element 2 will be described in more detail below with reference to FIG.

[0024] The anode body 4 includes a dielectric layer 41 and an anode-side conductive portion 42. The anode-side conductive portion 42 is flat. The dielectric layer 41 is formed on at least one surface of the anode-side conductive portion 42 in the thickness direction. The anode-side conductive portion 42 is a portion that functions as an anode in each capacitor element 2 and is made of a metal plate having conductivity. The dielectric layer 41 is formed so as to cover substantially the entire surface of the anode-side conductive portion 42, more specifically, on at least a portion of the surface of the anode-side conductive portion 42 where the solid electrolyte layer 5 is formed. Therefore, in this embodiment, the dielectric layer 41 is formed not only on one surface of the anode-side conductive portion 42 in the thickness direction, but also on both surfaces of the anode-side conductive portion 42 in the thickness direction.

[0025] Specifically, the anode body 4 contains a valve metal. Examples of the valve metal include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony, as well as alloys containing these. In the present embodiment, as an example, the valve metal contained in the anode body 4 is aluminum. That is, the anode-side conductive part 42 is a metal plate (metal foil) made of aluminum (Al). A coating of aluminum oxide (Al2O3), which is an oxide of aluminum, is formed on the surface of the anode-side conductive part 42, and this coating constitutes the dielectric layer 41.

[0026] The solid electrolyte layer 5 is formed on the surface of the anode body 4. The solid electrolyte layer 5 is formed on the dielectric layer 41, not directly on the anode-side conductive portion 42. That is, the solid electrolyte layer 5 is laminated on the anode-side conductive portion 42 via the dielectric layer 41. The solid electrolyte layer 5 is formed so as to cover substantially the entire surface of the anode body 4, except for the anode extraction portion 91 (see FIG. 3) and the insulating portion 92. Therefore, in this embodiment, the solid electrolyte layer 5 is formed on both sides of the anode body 4 in the thickness direction, not just on one side of the anode body 4 in the thickness direction.

[0027] In this embodiment, as described above, the solid electrolyte layer 5 contains a conductive polymer. The solid electrolyte layer 5 made of a conductive polymer has electrical conductivity mainly due to electronic conduction, and therefore can have a lower ESR than an electrolyte having electrical conductivity due to ionic conduction.

[0028] The cathode layer 8 includes a cathode-side conductive portion 82 and a carbon layer 81. The carbon layer 81 is formed directly on the surface of the solid electrolyte layer 5. The cathode-side conductive portion 82 is formed on the surface of the carbon layer 81. The cathode-side conductive portion 82 is made of a metal layer having electrical conductivity. The cathode-side conductive portion 82 is made of a silver (Ag) paste film, for example. Here, the cathode layer 8 covers at least a part of the solid electrolyte layer 5. In this embodiment, the cathode layer 8 covers only a part of the surface of the solid electrolyte layer 5, not the entire surface of the solid electrolyte layer 5. In other words, the solid electrolyte layer 5 includes an exposed portion 51 that is not covered by the cathode layer 8. That is, a part of the solid electrolyte layer 5 is not covered by the cathode layer 8 and is exposed from the cathode layer 8 as the exposed portion 51. In this embodiment, a portion of the solid electrolyte layer 5 with a certain width from the edge on the insulating portion 92 side is the exposed portion 51.

[0029] Cathode layer 8 is formed so as to cover substantially the entire surface of solid electrolyte layer 5 except for exposed portion 51. Therefore, in the present embodiment, cathode layer 8 is formed on the surface of solid electrolyte layer 5 not only on one side of anode body 4 in the thickness direction, but also on both sides of anode body 4 in the thickness direction.

[0030] 1, each capacitor element 2 is formed by laminating a solid electrolyte layer 5 and a cathode layer 8 in this order on both sides in the thickness direction (stacking direction) of an anode body 4. More specifically, the capacitor element 2 is formed by laminating a dielectric layer 41, a solid electrolyte layer 5, a carbon layer 81, and a cathode-side conductive portion 82 in this order on both sides in the thickness direction (stacking direction) of an anode-side conductive portion 42.

[0031] The solid electrolytic capacitor 1 according to this embodiment includes a plurality of capacitor elements 2 having the above-described configuration, and these plurality of capacitor elements 2 are stacked in the thickness direction (stacking direction) of each capacitor element 2 and integrated. A pair of adjacent capacitor elements 2 among the plurality of capacitor elements 2 are joined at a joint 20. In this embodiment, a pair of adjacent capacitor elements 2 among the plurality of capacitor elements 2 stacked in the stacking direction are electrically and mechanically connected to each other at the cathode side conductive portions 82 of the cathode layers 8 of each of the plurality of capacitor elements 2 stacked in the stacking direction. That is, the joint 20 joins the cathode side conductive portions 82 of the cathode layers 8 of a pair of capacitor elements 2 adjacent in the stacking direction. As an example, the joint 20 is realized by a conductive adhesive that joins the cathode layers 8 (the cathode side conductive portions 82) to each other.

[0032] The exterior resin 3 is a resin member that covers the capacitor element 2 having the above-described configuration. Since the solid electrolytic capacitor 1 according to this embodiment includes a plurality of capacitor elements 2, the exterior resin 3 covers the entire structure (laminate) in which the plurality of capacitor elements 2 are stacked in the stacking direction to form an integrated body. By covering the capacitor element 2, the exterior resin 3 suppresses the action of external stress, moisture, oxygen, and the like on the capacitor element 2. In this embodiment, as an example, the exterior resin 3 is made of epoxy resin.

[0033] Here, the exterior resin 3 contains a wax component 300 (see FIG. 4A). In the present disclosure, "wax" refers to an oily substance with a high melting point, which is an ester of a higher fatty acid and a monohydric or dihydric higher alcohol, as well as neutral fats, higher fatty acids, and hydrocarbons that have similar properties. Examples of the wax component 300 contained in the exterior resin 3 include carnauba wax and montanic acid ester. These wax components 300 have, for example, a function of improving the releasability of the exterior resin 3 during molding, or a function of giving the exterior resin 3 a gloss.

[0034] As described above, the coating layer 6 is located between the capacitor element 2 and the exterior resin 3. The coating layer 6 is made of a fluorine compound such as a resin containing fluorine. The coating layer 6 includes, for example, perfluoroalkyl methacrylate, perfluoroalkyl acrylate, or a perfluoropolyether group-containing silane compound. The fluorine compound includes, for example, one or more of polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and perfluoroalkyltrialkoxysilane.

[0035] 1, the covering layer 6 is formed on the surface of the capacitor element 2 so as to cover the capacitor element 2. In this embodiment, the covering layer 6 covers at least the exposed portion 51. In short, the covering layer 6 is formed on the surface of the capacitor element 2 so as to cover the portion of the solid electrolyte layer 5 that is not covered by the cathode layer 8 and is exposed from the cathode layer 8 as the exposed portion 51. However, in this embodiment, the covering layer 6 is formed from the exposed portion 51 to the cathode layer 8 so as to also cover the cathode layer 8 (the cathode side conductive portion 82) of the capacitor element 2. The thickness of the covering layer 6 is, for example, 5 μm or less, and more preferably 3 μm or less.

[0036] In this embodiment, the covering layer 6 is formed on at least a portion of the surface of each of the plurality of capacitor elements 2 excluding the joints 20. In other words, the covering layer 6 is not formed on the joints 20, but is formed so as to avoid the joints 20. As described above, the joints 20 join a pair of adjacent capacitor elements 2 among the plurality of capacitor elements 2, and in this embodiment, they join the cathode-side conductive portions 82 in the cathode layers 8 of each of the pair of capacitor elements 2. Therefore, the covering layer 6 is formed so as to avoid the joints 20 that join the cathode layers 8 (the cathode-side conductive portions 82) to each other.

[0037] In this embodiment, the coating layer 6 is located at least partially between a pair of adjacent capacitor elements 2 among the multiple capacitor elements 2. In other words, the coating layer 6 is also present in the gaps between the multiple capacitor elements 2 stacked in the stacking direction (see FIG. 1).

[0038] Here, since the coating layer 6 contains a fluorine compound, for example, due to its oil repellency, the wax component 300 is less likely to infiltrate from the exterior resin 3 into the capacitor element 2. In this embodiment, the coating layer 6 has oil repellency that results in a contact angle of 50 degrees or more. Specifically, when droplets of n-hexadecane (oil droplets) are attached to the surface of the coating layer 6, the static contact angle of the coating layer 6 with the n-hexadecane droplets, i.e., the contact angle of the coating layer 6 with respect to oil, is 50 degrees or more.

[0039] Furthermore, the coating layer 6 does not need to contain a fluorine compound as long as it has oil repellency. That is, the coating layer 6 can be realized by, for example, a resin having oil repellency, such as a silicone resin. Even if the coating layer 6 does not contain a fluorine compound, it is preferable that the coating layer 6 has oil repellency such that the contact angle is 50 degrees or more. The coating layer 6 having oil repellency makes it difficult for the wax component 300 to infiltrate from the exterior resin 3 into the capacitor element 2. Furthermore, it is more preferable that the coating layer 6 contains a fluorine compound and has oil repellency.

[0040] (3) Manufacturing method Next, a method for manufacturing solid electrolytic capacitor 1 according to this embodiment will be described.

[0041] The solid electrolytic capacitor 1 according to this embodiment is basically manufactured by the following procedure: the manufacturing method of the solid electrolytic capacitor 1 includes the steps of preparing an anode body, chemical conversion, forming a solid electrolyte layer, applying a cathode, laminating elements, welding an anode, molding resin, and processing terminals.

[0042] First, in the anode body preparation step, a metal plate (aluminum in this embodiment) having an oxide film on its surface that constitutes the dielectric layer 41 is subjected to a punching process or the like to form a base material that constitutes the anode body 4 of each capacitor element 2. In the chemical conversion step, the dielectric layer 41 is repaired on the base material. In the solid electrolyte layer formation step, a conductive polymer that constitutes the solid electrolyte layer 5 is formed on the base material. At this time, a conductive polymer (solid electrolyte layer 5) is formed on the surface of the base material (anode body 4) using a solution containing the conductive polymer or its raw material. In the cathode coating step, carbon and silver paste are applied in order on the surface of the solid electrolyte layer 5 of the base material to form the cathode layer 8 (carbon layer 81 and cathode-side conductive portion 82). In this way, each capacitor element 2 is completed.

[0043] Next, in the element stacking step, a plurality of capacitor elements 2 are stacked in the stacking direction, and the cathode layers 8 of a pair of adjacent capacitor elements 2 are joined together with a conductive adhesive that forms joint 20. At this time, the plurality of capacitor elements 2 are stacked on a conductive metal plate (lead frame) that forms first terminal 71 and second terminal 72. In the anode welding step, first terminal 71 is electrically and mechanically connected to anode lead portion 91 by welding.

[0044] In the subsequent resin molding process, exterior resin 3 is formed by transfer molding so as to cover the integrated structure (laminate) in which capacitor elements 2 are stacked in the stacking direction. At this time, exterior resin 3 is molded so that each of first terminal 71 and second terminal 72 is partially exposed from the surface of exterior resin 3. In the terminal processing process, the lead frame is cut into individual pieces, and first terminal 71 and second terminal 72 are bent. This completes solid electrolytic capacitor 1.

[0045] Meanwhile, the manufacturing method of the solid electrolytic capacitor 1 according to this embodiment further includes a resin coating step for forming a coating layer 6 containing a fluorine compound or having oil repellency. The resin coating step is performed before the resin molding step and after any one of the steps of cathode application, element lamination, and anodic welding. In this embodiment, as an example, the resin coating step is performed after the anodic welding step. In the resin coating step, a resin material containing a fluorine compound or having oil repellency is applied to the surface of a structure (laminate) in which the capacitor elements 2 are stacked in the stacking direction to form an integrated structure, thereby forming the coating layer 6.

[0046] By forming the coating layer 6 after the lamination process, the coating layer 6 is formed on at least a portion of the surface of each of the plurality of capacitor elements 2 excluding the joints 20, as described above. In other words, the coating layer 6 is not formed on the joints 20, but is formed so as to avoid the joints 20. Furthermore, in the resin coating process, the resin material that contains fluorine or has oil repellency is applied to the capacitor elements 2 so as to wrap around into the gaps between the stacked capacitor elements 2. As a result, the coating layer 6 is also formed on at least a portion of the gap between a pair of adjacent capacitor elements 2 among the plurality of capacitor elements 2.

[0047] The manufacturing method of solid electrolytic capacitor 1 may further include a drying step of capacitor element 2. The drying step of capacitor element 2 is performed before the resin molding step and after any one of the steps of cathode coating, element lamination, and anodic welding. In the drying step, for example, capacitor element 2 is placed in a high-temperature atmosphere (e.g., 200° C.) for a predetermined time to reduce the content of moisture 200 (see FIG. 4A) in capacitor element 2. By including such a drying step in the manufacturing method of solid electrolytic capacitor 1, the content of moisture 200 in capacitor element 2 can be reduced compared to a case where the drying step is not included.

[0048] (4) Comparative Example Next, a comparison result between the solid electrolytic capacitor 1 according to the present embodiment and a solid electrolytic capacitor 1X according to a comparative example will be described with reference to Figures 4A and 4B. The solid electrolytic capacitor 1X according to the comparative example has a common configuration with the solid electrolytic capacitor 1 according to the present embodiment, except that it does not have a coating layer 6. Figures 4A and 4B show a schematic representation of the wax component 300 contained in the exterior resin 3 and the moisture 200 contained in the capacitor element 2. In the following, it is assumed that the solid electrolytic capacitor 1, 1X is exposed to a high-temperature (e.g., 125°C) environment during the resin molding process for molding the exterior resin 3 or during use of the solid electrolytic capacitor 1, 1X.

[0049] In the solid electrolytic capacitor 1X according to the comparative example, as shown in FIG. 4B, there is no coating layer 6 between the capacitor element 2 and the exterior resin 3, so the wax component 300 contained in the exterior resin 3 is more likely to come into contact with the capacitor element 2 than in the solid electrolytic capacitor 1 according to the present embodiment. That is, there is no coating layer 6 between the capacitor element 2 and the exterior resin 3 to suppress the infiltration of the wax component 300 from the exterior resin 3 into the capacitor element 2, so the wax component 300 is more likely to infiltrate into the capacitor element 2 than in the solid electrolytic capacitor 1. Therefore, when the solid electrolytic capacitor 1X is exposed to a high-temperature environment, if the wax component 300 is heated to a high temperature, there is a possibility that the moisture 200 contained in the capacitor element 2 will come into contact with the high-temperature wax component 300. Then, if the high-temperature wax component 300 comes into contact with the moisture 200, the moisture 200 will be rapidly vaporized, and the capacitor element 2 may be damaged. As a result, in the solid electrolytic capacitor 1X according to the comparative example, the wax component 300 may affect the capacitor element 2, causing a change in the characteristics of the capacitor element 2.

[0050] On the other hand, in the solid electrolytic capacitor 1 according to the present embodiment, as shown in FIG. 4A, the coating layer 6 located between the capacitor element 2 and the exterior resin 3 makes the wax component 300 contained in the exterior resin 3 less likely to come into contact with the capacitor element 2 compared to the solid electrolytic capacitor 1X according to the comparative example. That is, the coating layer 6 containing a fluorine compound or the coating layer 6 having oil repellency makes it more difficult for the wax component 300 to infiltrate from the exterior resin 3 into the capacitor element 2 compared to the solid electrolytic capacitor 1X. In particular, in the present embodiment, the coating layer 6 covers at least the exposed portion 51 of the solid electrolyte layer 5 of the capacitor element 2, so that it is easy to suppress the contact of the wax component 300 contained in the exterior resin 3 with the solid electrolyte layer 5. As a result, even if the wax component 300 is heated to a high temperature when the solid electrolytic capacitor 1 is exposed to a high-temperature environment, the moisture 200 contained in the capacitor element 2 is less likely to come into contact with the high-temperature wax component 300. As a result, in the solid electrolytic capacitor 1 according to the present embodiment, the wax component 300 is less likely to affect the capacitor element 2, and the characteristics of the capacitor element 2 are less likely to change.

[0051] In particular, in this embodiment, the content of moisture 200 in capacitor element 2 is reduced by the drying process of capacitor element 2 (see "(3) Manufacturing method"). Therefore, in solid electrolytic capacitor 1 according to this embodiment, the amount of moisture 200 contained in capacitor element 2 is small to begin with, and moisture 200 contained in capacitor element 2 is less likely to come into contact with high-temperature wax component 300.

[0052] By comparing the solid electrolytic capacitor 1 according to the present embodiment with the solid electrolytic capacitor 1X according to the comparative example, the comparison results shown in Table 1 below were obtained. In Table 1, the rate of defective products due to leakage current (LC) is shown as "LC defect rate [%]", the number of damages caused to the capacitor element 2 is shown as "element damage [location]", and the result of the reliability test is shown as "reliability test [%]". The results of the reliability test show the rate of change [%] from the initial value when the sample (solid electrolytic capacitor 1, 1X) is heated to 125 [℃] for four items, "ΔC", "Δtan δ", "ΔESR", and "ΔLC". "ΔC" represents the rate of change in capacitance, "Δtan δ" represents the rate of change in tan δ (dielectric tangent), "ΔESR" represents the rate of change in equivalent series resistance, and "ΔLC" represents the rate of change in leakage current.

[0053] [Table 1]

[0054] As is clear from Table 1 above, the solid electrolytic capacitor 1 according to this embodiment shows improvements in all items compared to the solid electrolytic capacitor 1X according to the comparative example. In particular, the results of the reliability test show that the solid electrolytic capacitor 1 according to this embodiment is less susceptible to changes in the characteristics of the capacitor element 2 ("ΔC", "Δtan δ", "ΔESR", and "ΔLC") compared to the solid electrolytic capacitor 1X according to the comparative example.

[0055] (5) Variations The first embodiment is merely one of various embodiments of the present disclosure. The first embodiment can be modified in various ways depending on the design and the like as long as the object of the present disclosure can be achieved. The modified examples described below can be applied in appropriate combination.

[0056] Solid electrolytic capacitor 1 is not limited to a two-terminal structure having two terminals, first terminal 71 and second terminal 72, and may have a structure having three or more terminals.

[0057] Furthermore, the solid electrolyte layer 5 is not limited to a conductive polymer, and may be, for example, manganese dioxide or an organic semiconductor.

[0058] Furthermore, the coating layer 6 may be between the capacitor element 2 and the exterior resin 3, and it is not essential for the solid electrolytic capacitor 1 that the coating layer 6 is formed directly on the surface of the capacitor element 2. As an example, a protective layer made of a polyamide resin, a polyimide resin, a polyimide silicone resin, ceramics, or the like may be formed on the surface of the capacitor element 2, and the coating layer 6 may be formed on the surface of the protective layer. In this case, it is preferable that the protective layer covers at least the exposed portion 51 of the solid electrolyte layer 5 in the same manner as the coating layer 6. Conversely, the coating layer 6 may be formed on the surface of the capacitor element 2, and the above-mentioned protective layer may be formed on the surface of the coating layer 6.

[0059] Furthermore, the exterior resin 3 does not have to constitute the outermost shell of the solid electrolytic capacitor 1. For example, the exterior resin 3 may be covered with a further resin member by double molding (two-color molding) or the like.

[0060] Furthermore, the number of capacitor elements 2 included in solid electrolytic capacitor 1 is not limited to seven, and for example, an appropriate number of capacitor elements 2 between 2 and 10 may be stacked.

[0061] Furthermore, in capacitor element 2, the formation of solid electrolyte layer 5 and cathode layer 8 on both sides of anode body 4 in the thickness direction is not an essential component of solid electrolytic capacitor 1; for example, solid electrolyte layer 5 and cathode layer 8 may be formed on only one side of anode body 4 in the thickness direction.

[0062] The resin coating step for forming the coating layer 6 is not limited to being performed after the element stacking step, and may be performed, for example, after the cathode coating step and before the element stacking step. The method for forming the coating layer 6 is not limited to coating, and the coating layer 6 may be formed, for example, by attaching a resin sheet containing a fluorine compound to the surface of the capacitor element 2.

[0063] Moreover, the anode-side conductive portion 42 is not limited to aluminum, and may be, for example, tantalum, etc. Moreover, the shape of the anode body 4 (the anode-side conductive portion 42 and the dielectric layer 41) is not limited to a flat plate, and may be, for example, a porous sintered body formed from valve action metal powder.

[0064] (summary) As described above, the solid electrolytic capacitor (1) according to the first embodiment includes at least one capacitor element (2), an exterior resin (3), and a coating layer (6). The capacitor element (2) includes an anode body (4) including a dielectric layer (41), and a solid electrolyte layer (5) covering at least a portion of the dielectric layer (41). The exterior resin (3) covers the capacitor element (2). The coating layer (6) is located between the capacitor element (2) and the exterior resin (3), and contains a fluorine compound.

[0065] According to this embodiment, the coating layer (6) located between the capacitor element (2) and the exterior resin (3) makes it difficult for the oil contained in the exterior resin (3) to come into contact with the capacitor element (2) compared to a configuration without the coating layer (6). That is, the coating layer (6) containing a fluorine compound makes it difficult for the oil to penetrate from the exterior resin (3) to the capacitor element (2). Therefore, for example, when the solid electrolytic capacitor (1) is exposed to a high-temperature environment, even if the oil in the exterior resin (3) is heated to a high temperature, the oil is unlikely to affect the capacitor element (2), and the characteristics of the capacitor element (2) are unlikely to change.

[0066] A solid electrolytic capacitor (1) according to a second embodiment includes at least one capacitor element (2), an exterior resin (3), and a coating layer (6). The capacitor element (2) includes an anode body (4) including a dielectric layer (41), and a solid electrolyte layer (5) covering at least a portion of the dielectric layer (41). The exterior resin (3) covers the capacitor element (2). The coating layer (6) is located between the capacitor element (2) and the exterior resin (3), and has oil repellency.

[0067] According to this embodiment, the coating layer (6) located between the capacitor element (2) and the exterior resin (3) makes it difficult for oil contained in the exterior resin (3) to come into contact with the capacitor element (2) compared to a configuration without the coating layer (6). In other words, the oil-repellent coating layer (6) makes it difficult for oil to penetrate from the exterior resin (3) to the capacitor element (2). Therefore, for example, when the solid electrolytic capacitor (1) is exposed to a high-temperature environment, even if the oil in the exterior resin (3) is heated to a high temperature, the oil is unlikely to affect the capacitor element (2), and the characteristics of the capacitor element (2) are unlikely to change.

[0068] In the solid electrolytic capacitor (1) according to the third embodiment, in the first or second embodiment, the exterior resin (3) contains a wax component (300).

[0069] According to this embodiment, the wax component (300) is expected to have the effects of improving the releasability during molding of the exterior resin (3) and giving the exterior resin (3) a glossy finish, etc. Furthermore, the coating layer (6) located between the capacitor element (2) and the exterior resin (3) makes it difficult for the wax component (300) to come into contact with the capacitor element (2).

[0070] In a solid electrolytic capacitor (1) according to a fourth aspect, in any one of the first to third aspects, the capacitor element (2) further includes a cathode layer (8) covering at least a portion of the solid electrolyte layer (5). The solid electrolyte layer (5) includes an exposed portion (51) that is not covered by the cathode layer (8). The covering layer (6) covers at least the exposed portion (51).

[0071] According to this embodiment, the covering layer (6) makes it difficult for oil to infiltrate into the exposed portion (51), where the infiltration of oil is likely to affect the characteristics of the capacitor element (2).

[0072] The solid electrolytic capacitor (1) according to a fifth aspect is any one of the first to fourth aspects and includes a plurality of capacitor elements (2). The plurality of capacitor elements (2) are stacked on top of each other and covered with a single exterior resin (3).

[0073] According to this embodiment, since the plurality of capacitor elements (2) are covered with one exterior resin (3), the exterior resin (3) can also mitigate stress acting between the plurality of capacitor elements (2).

[0074] In the solid electrolytic capacitor (1) according to the sixth aspect, in the fifth aspect, a pair of adjacent capacitor elements (2) among the plurality of capacitor elements (2) are joined at a joint (20). A coating layer (6) is formed on at least a portion of the surface of each of the plurality of capacitor elements (2) excluding the joint (20).

[0075] According to this embodiment, the coating layer (6) is formed on the area other than the joint (20), so that problems such as the coating layer (6) acting on the joint (20) and reducing the bonding strength of the joint (20) are unlikely to occur.

[0076] The solid electrolytic capacitor (1) according to a seventh aspect is the fifth or sixth aspect, in which a covering layer (6) is located at least partially between a pair of adjacent capacitor elements (2) among the plurality of capacitor elements (2).

[0077] According to this embodiment, the coating layer (6) is also present in the gap between a pair of adjacent capacitor elements (2), making it more difficult for oil contained in the exterior resin (3) to come into contact with the capacitor elements (2).

[0078] In the solid electrolytic capacitor (1) according to the eighth aspect, in any one of the first to seventh aspects, the covering layer (6) has oil repellency such that the contact angle is 50 degrees or more.

[0079] According to this embodiment, since the covering layer (6) has sufficient oil repellency, the infiltration of oil from the exterior resin (3) into the capacitor element (2) is more unlikely to occur.

[0080] In a solid electrolytic capacitor (1) according to a ninth aspect, in any of the first to eighth aspects, the anode body (4) includes a flat anode-side conductive portion (42) and a dielectric layer (41) formed on at least one surface in a thickness direction of the anode-side conductive portion (42).

[0081] According to this embodiment, since the anode body (4) is in a flat plate shape, the height or thickness of the solid electrolytic capacitor (1) can be reduced.

[0082] In the solid electrolytic capacitor (1) according to a tenth aspect, in any one of the first to ninth aspects, the solid electrolyte layer (5) contains a conductive polymer.

[0083] According to this embodiment, the equivalent series resistance can be kept low.

[0084] The configurations according to the second to tenth aspects are not essential for the solid electrolytic capacitor (1) and may be omitted as appropriate. [Explanation of symbols]

[0085] 1. Solid electrolytic capacitor 2. Capacitor elements 3 Exterior resin 4 Anode body 5 Solid electrolyte layer 6 Covering layer 8 Cathode Layer 20 Joint 41 Dielectric layer 42 Anode side conductive part 51 Exposed areas 300 Wax components

Claims

1. an anode body including a dielectric layer; a solid electrolyte layer covering at least a portion of the dielectric layer; a cathode layer covering at least a portion of the solid electrolyte layer; and an exterior resin that covers a laminate in which the plurality of capacitor elements are stacked on top of each other; a layer containing a fluorine compound and positioned between the laminate and the exterior resin; Equipped with The exterior resin contains a wax component, When one of a pair of adjacent capacitor elements among the plurality of capacitor elements is a first capacitor element and the other is a second capacitor element, the solid electrolyte in the first capacitor element includes a first exposed portion that is not covered by the cathode layer; the solid electrolyte in the second capacitor element includes a second exposed portion that is not covered by the cathode layer; the first exposed portion and the second exposed portion face each other via the layer containing a fluorine compound.

2. the first exposed portion and the second exposed portion are in contact with the layer containing the fluorine compound; The solid electrolytic capacitor according to claim 1 .

3. The layer containing the fluorine compound has oil repellency such that the contact angle is 50 degrees or more. The solid electrolytic capacitor according to claim 1 or 2.

4. The first capacitor element and the second capacitor element are joined at a joint. The solid electrolytic capacitor according to any one of claims 1 to 3.

5. The solid electrolyte layer includes a conductive polymer. The solid electrolytic capacitor according to any one of claims 1 to 4.

6. A method for producing the solid electrolytic capacitor according to claim 1, comprising the steps of: A first step of preparing a laminate including a plurality of capacitor elements stacked together, the capacitor elements including an anode body including a dielectric layer, a solid electrolyte layer covering at least a portion of the dielectric layer, and a cathode layer covering at least a portion of the solid electrolyte layer; A second step of applying a resin containing a fluorine compound to the laminate; A third step of covering the laminate with an exterior resin containing a wax component, In the laminate prepared in the first step, when one of a pair of adjacent capacitor elements is a first capacitor element and the other is a second capacitor element, the solid electrolyte in the first capacitor element includes a first exposed portion that is not covered by the cathode layer, and the solid electrolyte in the second capacitor element includes a second exposed portion that is not covered by the cathode layer, The third step is carried out after the second step. A method for manufacturing a solid electrolytic capacitor.

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