Electrolytic capacitors

Abstract

To suppress the decrease in sealability of an electrolytic capacitor due to the occurrence of a crack in a mold resin layer.SOLUTION: An electrolytic capacitor 1A includes a capacitor element 10 including a pair of electrodes, an electrolyte solution, a case 11 that accommodates the capacitor element and the electrolyte solution, a sealing member 12, a pair of leads 14A and 14B that penetrate the sealing member, and a mold resin layer 13. The case includes an opening. The sealing member seals the opening of the case. The pair of leads are electrically connected to the pair of electrodes. The mold resin layer covers at least a part of an external surface of the sealing member facing the opening side of the case. At least one of the pair of leads includes a tab part 16A, 16B and an extraction part 15A, 15B. The tab part is connected to the electrode. The extraction part is connected to one end part of the tab part. The one end part of the tab part protrudes from an outer surface of the sealing member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an electrolytic capacitor including a mold resin layer that covers a sealing member. [Background technology]

[0002] The electrolytic capacitor includes a capacitor element including a pair of electrodes, an electrolyte between the pair of electrodes, a case that contains the capacitor element and the electrolyte and has an opening, a sealing member that seals the opening of the case, and a pair of leads that are electrically connected to the pair of electrodes and pass through the sealing member. Each lead includes a tab portion made mainly of aluminum, for example, and a lead portion connected to one end of the tab portion. The tab portion is connected to the electrode inside the case, and the lead portion is led out to the outside of the case.

[0003] The sealing material may deteriorate due to oxidation in a high-temperature environment, and when the sealing material deteriorates, the sealing performance of the electrolytic capacitor decreases. In addition, the electrolyte components tend to permeate the sealing material, evaporate, and gradually decrease. Therefore, in order to improve the sealing performance inside the case, it has been proposed to cover the outer surface of the sealing material facing the opening side of the case with a molded resin layer (Patent Document 1). By providing the molded resin layer, the electrolyte components are prevented from evaporating outside the case. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 60-245106 Summary of the Invention

[0005] An electrolytic capacitor according to a first aspect of the present disclosure includes a capacitor element including a pair of electrodes, an electrolyte interposed between the pair of electrodes, a case housing the capacitor element and the electrolyte, a sealing member, a pair of leads penetrating the sealing member, and a molded resin layer. The case has an opening. The sealing member seals the opening of the case. The pair of leads are electrically connected to the pair of electrodes, respectively. The molded resin layer covers at least a portion of an outer surface of the sealing member facing the opening side. At least one of the pair of leads has a tab portion and an extension portion. The tab portion is connected to the electrode. The extension portion is connected to one end of the tab portion. One end of the tab portion protrudes from the outer surface of the sealing member.

[0006] According to the present disclosure, in an electrolytic capacitor having a molded resin layer that covers at least a portion of the outer surface of a sealing member facing the open side of a case, corrosion of the leads can be suppressed.

[0007] Also, an electrolytic capacitor according to a second aspect of the present disclosure includes a capacitor element including a pair of electrodes, an electrolytic solution interposed between the pair of electrodes, a case accommodating the capacitor element and the electrolytic solution, a sealing member, a molded resin layer covering the sealing member, and a pair of leads penetrating the sealing member and the molded resin layer. The case has an opening. The sealing member seals the opening of the case. The pair of leads are electrically connected to the pair of electrodes, respectively. At least one of the pair of leads has an insulating region covered with an electrical insulating layer. The electrical insulating layer is provided between at least one of the pair of leads and at least one of the sealing member and the molded resin layer.

[0008] According to the present disclosure, it is possible to suppress corrosion of the leads of an electrolytic capacitor having a mold resin layer covering a sealing material.

[0009] Also, an electrolytic capacitor according to a third aspect of the present disclosure includes a capacitor element including a pair of electrodes, a case that houses the capacitor element, a sealing member, a molded resin layer that covers the sealing member, and a pair of leads that penetrate the sealing member and the molded resin layer. The case has an opening. The sealing member seals the opening of the case. The pair of leads are electrically connected to the pair of electrodes, respectively. A gap is provided between the sealing member and the molded resin layer.

[0010] According to the present disclosure, it is possible to suppress deterioration of the sealing property of the electrolytic capacitor caused by the occurrence of cracks in the molded resin layer. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of an electrolytic capacitor according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram illustrating a configuration of an example of a capacitor element. [Diagram 3] FIG. 2 is a schematic cross-sectional view of an electrolytic capacitor according to a first modified example of the first embodiment of the present disclosure. [Figure 4] FIG. 11 is a schematic cross-sectional view of an electrolytic capacitor according to a second modified example of the first embodiment of the present disclosure. [Diagram 5] 1 is a schematic cross-sectional view of an electrolytic capacitor according to a reference embodiment of the present disclosure. [Figure 6] 6 is a cross-sectional view of a main part showing the vicinity of the boundary between the sealing material and the mold resin layer in FIG. 5. [Figure 7] FIG. 4 is a schematic cross-sectional view of an electrolytic capacitor according to a second embodiment of the present disclosure. [Figure 8] FIG. 11 is a schematic cross-sectional view of an electrolytic capacitor according to a modified example of the second embodiment of the present disclosure. [Figure 9] 1 is a cross-sectional view of a main portion of an electrolytic capacitor in which an electrical insulating layer is provided and then the rod-shaped portion is inserted into a sealing material so that the joint between the drawn portion and the rod-shaped portion is positioned within a hole in the sealing material. [Figure 10]1 is a cross-sectional view of a main portion of an electrolytic capacitor in which an electrical insulating layer is provided and then the rod-shaped portion is inserted into a sealing material so that the joint between the drawn portion and the rod-shaped portion is positioned outside the hole in the sealing material. [Figure 11] 1 is a cross-sectional view of a main portion of an electrolytic capacitor in which an electrical insulating layer is provided after the rod-shaped portion is inserted into the sealing material so that the joint between the drawn portion and the rod-shaped portion is positioned within the hole of the sealing material. [Figure 12] 13 is a cross-sectional view of a main portion of an electrolytic capacitor in which an electrical insulating layer is provided after the rod-shaped portion is inserted into the sealing material so that the joint between the drawn portion and the rod-shaped portion is positioned outside the hole of the sealing material. FIG. [Figure 13] FIG. 11 is a schematic cross-sectional view of an electrolytic capacitor according to a third embodiment of the present disclosure. [Figure 14] This is a cross-sectional view of a key portion of an electrolytic capacitor when a gap is formed while the rod-shaped portion is inserted into a hole in a sealing material so that the joint between the drawn-out portion and the rod-shaped portion is positioned within the hole in the sealing material. [Figure 15] This is a cross-sectional view of a key portion of an electrolytic capacitor when a gap is formed when the rod-shaped portion is inserted into a hole in a sealing material so that the joint between the drawn-out portion and the rod-shaped portion is located outside the hole in the sealing material. [Figure 16] FIG. 11 is a schematic cross-sectional view of an electrolytic capacitor according to a modified example of the third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Prior to describing the embodiments of the present disclosure, problems in the prior art will be briefly described. A pair of leads penetrates the sealing member and the molded resin layer, and is drawn out from the mounting surface side of the molded resin layer. An electrolyte (e.g., a solvent) is relatively easy to permeate through a sealing member containing a rubber component, but is difficult to permeate through the molded resin layer. Therefore, when the outer surface of the sealing member is covered with a molded resin layer, the electrolyte may remain inside the sealing member or at the boundary between the sealing member and the molded resin layer. In such a case, the chlorine component (a component containing chlorine) contained in the sealing member is likely to dissolve into the electrolyte. If the lead comes into contact with an electrolyte containing a chlorine component, corrosion of the lead may progress.

[0013] More specifically, the structure of an example of an electrolytic capacitor according to a reference embodiment of the present disclosure will be described with reference to FIGS.

[0014] Electrolytic capacitor 1D includes a capacitor element 10, an electrolyte (not shown), and a case 11 that accommodates capacitor element 10 and the electrolyte. An opening of case 11 is sealed with a sealing member 12. An outer surface of sealing member 12 facing the opening of case 11 (hereinafter also simply referred to as the outer surface of sealing member 12) is covered with a molded resin layer 13. Leads 14A, 14B are connected to a pair of electrodes of capacitor element 10, respectively.

[0015] The leads 14A and 14B have tab portions 16A and 16B connected to one and the other electrodes, respectively, and lead portions 15A and 15B connected to the tab portions 16A and 16B, respectively. The connection portions between the tab portions 16A and 16B and the lead portions 15A and 15B are hereinafter also referred to as internal lead connection portions 175A and 175B.

[0016] One electrode is an anode and the other electrode is a cathode. The anode has a dielectric layer on a surface thereof. The electrolytic capacitor may include a solid electrolyte layer covering at least a portion of a surface of the dielectric layer. One lead is an anode lead connected to the anode and the other lead is a cathode lead connected to the cathode.

[0017] In the illustrated example, the tab portions 16A and 16B have rod-shaped portions 17A and 17B and flat portions 18A and 18B, respectively. The flat portions 18A and 18B are connected to the anode and cathode, respectively. The rod-shaped portions 17A and 17B are connected to the lead-out portions 15A and 15B, respectively. At least a portion of the lead-out portions 15A and 15B is drawn out from the mounting surface 13S of the molded resin layer 13 to the outside and accommodated in the groove portions 13A and 13B provided in the mounting surface 13S. It is preferable that the bottom surfaces 13a and 13b of the groove portions 13A and 13B have a predetermined inclination.

[0018] One end (hereinafter also referred to as the tip) of the rod-shaped parts 17A and 17B is located in a through hole provided in the sealing member 12. Electrolyte components tend to accumulate near the boundary between the sealing member 12 and the molded resin layer 13. When the tip of the rod-shaped parts 17A and 17B is located in the through hole of the sealing member 12, the electrolyte components accumulating near the boundary between the sealing member 12 and the molded resin layer 13 tend to come into contact with the lead internal connections 175A and 175B and the drawn-out parts 15A and 15B. At this time, the accumulating electrolyte components corrode the lead internal connections 175A and 175B and the drawn-out parts 15A and 15B. Furthermore, if the electrolyte penetrates into a wide range of the boundary between the sealing member 12 and the molded resin layer 13 and electrolyte components remain between the lead internal connections 175A, 175B and / or the lead portions 15A, 15B of a pair of leads 14A, 14B, corrosion of the lead internal connections 175A, 175B and / or the lead portions 15A, 15B (especially the anode lead side) is accelerated when a voltage is applied between the leads. Furthermore, as shown in FIG. 6, when the tip portions of the rod-shaped portions 17A, 17B are located in the through holes of the sealing member, gaps are likely to occur between the leads 14A, 14B and the molded resin layer 13. Electrolyte components are likely to remain in such gaps, accelerating corrosion of the lead internal connections 175A, 175B and / or the lead portions 15A, 15B.

[0019] (First embodiment) The electrolytic capacitor according to the first embodiment of the present disclosure includes a capacitor element including a pair of electrodes, an electrolytic solution interposed between the pair of electrodes, a case for accommodating the capacitor element and the electrolytic solution, a sealing member, a pair of leads penetrating the sealing member, and a molded resin layer. The sealing member seals the opening of the case. The pair of leads are electrically connected to the pair of electrodes, respectively. The molded resin layer covers at least a portion of the outer surface of the sealing member. At least one of the pair of leads has a tab portion and an extended portion. The tab portion is connected to the electrode. The extended portion is connected to a tip portion of the tab portion. The tip portion of the tab portion protrudes from the outer surface of the sealing member. This prevents the retained electrolyte component from coming into contact with the connection portion between the tip portion of the rod-shaped portion and the extended portion. This makes it less likely that defects such as lead breakage will occur.

[0020] Among the lead, the tab portion (or the rod-shaped portion and the flat portion) is originally a portion housed in the case, and is therefore formed of a material (such as a valve metal) that is unlikely to corrode due to contact with the electrolyte. For example, the tab portion is covered with an oxide film, and therefore unlikely to corrode. On the other hand, the connection portion between the tab portion and the lead portion (internal lead connection portion) and the subsequent lead portion contain a material that is prone to corrosion (transition metals such as Fe and Cu), such as a CP wire or a Cu wire. By projecting the end portion (or the tip portion of the rod-shaped portion) of the tab portion on the lead portion side from the sealing material, the internal lead connection portion and the subsequent lead portion can be separated from the boundary between the molded resin layer and the sealing material. This suppresses contact between the electrolyte component and the internal lead connection portion and the lead portion.

[0021] When a voltage is applied while both of the pair of leads are in contact with the stagnant electrolyte components, the lead components are electrolyzed, accelerating the corrosion of the leads. Therefore, by suppressing the contact between at least one of the pair of leads and the electrolyte components, the corrosion of the leads can be suppressed. Since the anode lead is more likely to corrode than the cathode lead, it is preferable that at least the end of the anode lead on the lead-out side (or the tip of the rod-shaped part) protrudes from the outer surface of the sealing member. However, in order to enhance the effect of suppressing the corrosion of the leads, it is desirable to suppress the contact between both of the pair of leads and the electrolyte components.

[0022] The lead internal connection may be embedded in the molded resin layer. This forms an adhesive interface between the molded resin layer and the lead internal connection. Since the electrolyte component that remains is unlikely to penetrate into the adhesive interface, the effect of suppressing corrosion of the lead is enhanced. The lead internal connection usually has a weld mark between the tab portion and the pull-out portion. If at least a part of the weld mark is covered with the molded resin layer, a corresponding corrosion suppression effect can be obtained.

[0023] The end of the tab portion on the pull-out side may have an exposed portion that is not covered with the molded resin layer. The exposed portion does not form an adhesive interface between the molded resin layer and the lead, so that the electrolyte solution components do not creep up to the exposed portion due to capillary action. The exposed portion is constantly exposed to the outside air, so that it is difficult for it to become wet with the electrolyte solution components and is easy to dry. This prevents the lead from coming into contact with the electrolyte solution components.

[0024] The entire tab portion protruding from the outer surface of the sealing member may be exposed without being covered with the molded resin layer. In this case, a region without the molded resin layer is formed around the through hole through which the lead passes, so as to surround the through hole. At this time, a boundary between the molded resin layer and the sealing member is not formed around the tab portion protruding from the sealing member, and this portion is exposed to the outside. Therefore, retention of the electrolyte component around the tab portion protruding from the sealing member is further suppressed.

[0025] On the other hand, the end of the tab portion on the lead-out side may be embedded in the molded resin layer so that the entire weld mark is covered with the molded resin layer. In this case, a part of the lead-out portion continuing from the end of the tab portion on the lead-out side may also be embedded in the molded resin layer.

[0026] The tab portion is preferably covered with an oxide film of the metal that constitutes the tab portion. This makes it difficult for corrosion to occur due to contact between the tab portion and the electrolyte components. For example, when the tab portion includes a valve metal such as aluminum, the tab portion can be anodized to form an oxide film on the tab portion. It is sufficient to form the oxide film only on the anode lead, but the oxide film may also be formed on the cathode lead.

[0027] The lead-out portion is preferably a flexible linear member. The linear member preferably includes a core material and a plating layer that covers the surface of the core material. The core material is preferably mainly composed of, for example, Cu, steel, or Fe, which has excellent electrical conductivity. The plating layer is preferably formed of a low-melting point metal. By providing the lead-out portion with a plating layer of a low-melting point metal, it becomes easy to connect the lead-out portion to a predetermined connected electrode. Specifically, a CP wire, a Cu wire, or the like can be used for the lead-out portion. A CP wire is a linear member whose core material is formed of steel or Fe, or the like, and whose plating layer is formed of Sn, Cu, or the like. A Cu wire is a linear member whose core material is formed of Cu, and whose plating layer is formed of Sn, or the like.

[0028] When the lead-out portion contains a transition metal, the transition metal is likely to dissolve from the lead-out portion into the electrolyte solution components. By protruding the end of the tab portion on the lead-out portion side from the outer surface of the sealing member, corrosion of the lead-out portion is significantly suppressed.

[0029] The evaporation of the electrolyte component is suppressed from the outer surface of the sealing member covered with the molded resin layer. Therefore, the molded resin layer may cover at least a part of the outer surface of the sealing member. As already mentioned, a region not having the molded resin layer may be provided around the through hole for passing the lead on the outer surface of the sealing member so as to surround the through hole. However, it is preferable that the region of the outer surface of the sealing member other than the periphery of the through hole is covered with the molded resin layer. In this case, it is preferable that 50% or more of the area of ​​the outer surface of the sealing member is covered with the molded resin layer. The entire area (100%) of the outer surface of the sealing member may be covered with the molded resin layer.

[0030] The molded resin layer preferably covers not only the outer surface of the sealing member but also at least a part of the side surface leading to the opening of the case. This can further improve the airtightness inside the case. The molded resin layer preferably adheres closely to the case in a region facing the case. This can more firmly fix the molded resin layer to the sealing member.

[0031] Hereinafter, the electrolytic capacitor according to the first embodiment of the present disclosure will be specifically described with reference to the drawings, but the present disclosure is not limited thereto.

[0032] 1 includes a capacitor element 10, an electrolyte (not shown), and a case 11 that houses these and has an opening. Case 11 is, for example, cylindrical with a bottom. The opening of case 11 is sealed with a sealing member 12. The outer surface of sealing member 12 facing the opening side of case 11 is entirely covered with a molded resin layer 13. Molded resin layer 13 is provided so as to cover the opening of case 11 together with the outer surface of sealing member 12, and further covers at least a portion of the side surface of case 11 continuing to the opening.

[0033] After accommodating capacitor element 10, the opening of case 11 is sealed with sealing material 12 and molded resin layer 13. The open end of case 11 is drawn toward sealing material 12 and crimped inward. This fixes sealing material 12 to the opening of case 11, and case 11 is sealed by sealing material 12. It is sufficient that molded resin layer 13 is partially bonded to case 11 in the region facing case 11, and there may be some parts that are not bonded.

[0034] The mold resin layer 13 preferably contains a cured product of a curable resin composition. The curable resin composition may contain, in addition to the curable resin, a filler, a curing agent, a polymerization initiator, and / or a catalyst. Examples of the curable resin include a photocurable resin and a thermosetting resin. The curing agent, polymerization initiator, catalyst, and the like are appropriately selected depending on the type of the curable resin.

[0035] As the curable resin, for example, a compound (for example, a monomer, an oligomer, a prepolymer, etc.) that is cured or polymerized by the action of heat is used. Examples of such compounds (or curable resins) include epoxy resins, phenolic resins, urea resins, polyimides, polyamideimides, polyurethanes, diallyl phthalates, unsaturated polyesters, etc. The curable resin composition may contain a plurality of curable resins.

[0036] As the filler, for example, insulating particles (inorganic, organic) and / or fibers are preferable. As the insulating material constituting the filler, for example, insulating compounds (oxides, etc.) such as silica and alumina, glass, mineral materials (talc, mica, clay, etc.) and the like can be mentioned. The molded resin layer may contain one type of these fillers or a combination of two or more types. The content ratio of the filler in the molded resin layer is, for example, 10 mass % or more and 90 mass % or less.

[0037] The mold resin layer 13 may contain a thermoplastic resin or a composition containing the thermoplastic resin. As the thermoplastic resin, for example, polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), etc. can be used.

[0038] The molded resin layer 13 can be formed using a molding technique such as injection molding, insert molding, compression molding, etc. The molded resin layer 13 can be formed, for example, by using a predetermined mold and filling a curable resin composition or a thermoplastic resin (composition) into a predetermined location in the mold so as to cover the opening of the case 11 together with the outer surface of the sealing member 12.

[0039] 2 is formed by winding an anode 21 and a cathode 22 with a separator 23 interposed therebetween. An anode lead 14A and a cathode lead 14B are electrically connected to the anode 21 and the cathode 22, respectively. Each lead penetrates the sealing material 12 and is drawn out to the outside.

[0040] The anode lead 14A and the cathode lead 14B have tab portions 16A and 16B connected to the anode 21 and the cathode 22, respectively, and lead portions 15A and 15B connected to the tab portions 16A and 16B, respectively. The tab portions 16A and 16B include, for example, aluminum. The lead portions 15A and 15B are, for example, CP wires or Cu wires including metals such as iron, copper, nickel, and tin. When the electrolytic capacitor 1A is mounted on a substrate, the connected electrodes on the substrate and the leads 14A and 14B of the capacitor element 10 are electrically connected via the lead portions 15A and 15B.

[0041] The tab portions 16A and 16B each have a rod-shaped portion 17A, 17B and a flat portion 18A, 18B. The rod-shaped portions 17A, 17B and the flat portions 18A, 18B may be integral as long as they are electrically connected to each other. For example, the flat portion is formed by rolling a part of the rod-shaped body. The area that is not rolled remains as a rod-shaped portion. This allows the tab portions 16A and 16B to be formed in which the flat portion and the rod-shaped portion are integrated.

[0042] The rod-shaped portions 17A and 17B each penetrate the sealing member 12. The shape of the rod-shaped portions 17A and 17B is not particularly limited, and may be a round rod (for example, a rod having a circular or elliptical cross section) or a square rod (for example, a rod having a polygonal cross section). The rod-shaped portions 17A and 17B are connected to the capacitor element 10 via the flat portions 18A and 18B, respectively. The flat portions 18A and 18B facilitate the connection of the leads 14A and 14B to the anode and cathode.

[0043] Lead portions 15A, 15B are connected to the tips of rod-shaped portions 17A, 17B by welding or the like, and lead internal connection portions 175A, 175B are formed at the boundaries between lead portions 15A, 15B and the rod-shaped portions. At least a portion of lead portions 15A, 15B passes through molded resin layer 13 and is drawn out to the outside. The shape of lead portions 15A, 15B is not particularly limited, and may be, for example, a wire shape or a ribbon shape.

[0044] The tips of the rod-shaped parts 17A and 17B protrude from the outer surface of the sealing member 12. The distance D between the lead-inside connection parts 175A and 175B or the part of the weld mark closest to the drawn-out part corresponding to the tip of the rod-shaped parts 17A and 17B and the outer surface of the sealing member 12 is preferably as large as possible from the viewpoint of suppressing contact between the drawn-out parts 15A and 15B or the lead-inside connection parts 175A and 175B and the electrolyte solution components. The distance D is preferably 5% or more of the maximum thickness T of the molded resin layer 13. At this time, it is preferable that the tips of the rod-shaped parts 17A and 17B do not protrude from the mounting surface 13S of the molded resin layer 13. Here, the maximum thickness T of the molded resin layer 13 is the maximum value of the vertical distance between the mounting surface 13S of the molded resin layer 13 and the outer surface of the sealing member 12. The vertical distance refers to the distance in the normal direction of the outer surface of the sealing member 12.

[0045] In the above configuration, the lead internal connection parts 175A, 175B are embedded in the molded resin layer 13. The tip parts of the rod-shaped parts 17A, 17B are entirely covered with the molded resin layer 13, and an adhesive interface between the molded resin layer 13 and the tip parts of the rod-shaped parts 17A, 17B is formed with a sufficiently large area. This adhesive interface significantly suppresses contact between the lead internal connection parts 175A, 175B or the drawn-out parts 15A, 15B and the electrolyte solution components.

[0046] 1, elongated grooves 13A and 13B are provided on mounting surface 13S of molded resin layer 13. Lead-out portions 15A and 15B have portions led out from mounting surface 13S to the outside. These portions are accommodated in grooves 13A and 13B, and are thereby disposed near mounting surface 13S.

[0047] The bottom surfaces 13a, 13b are inclined so that the depth of the grooves 13A, 13B gradually increases from the points where the lead-out portions 15A, 15B start to be led out from the molded resin layer 13 toward the outer periphery of the mounting surface 13S. When the lead-out portions 15A, 15B are bent substantially parallel to the mounting surface 13S, a restoring force acts on the lead-out portions 15A, 15B to return them to their original shapes. Taking this restoring force into consideration, the bottom surfaces of the grooves 13A, 13B are provided with the above-mentioned inclination. The inclination angle of the bottom surfaces 13a, 13b with respect to the mounting surface 13S is, for example, 3° or more and 30° or less. The depth of the grooves 13A, 13B may be constant without inclining the bottom surfaces 13a, 13b.

[0048] The sealing member 12 may be made of an insulating material. An elastic material is preferable as the insulating material. By using the sealing member 12 containing an elastic material such as rubber, high sealing performance can be ensured. From the viewpoint of easily obtaining high heat resistance, silicone rubber, fluororubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber (Hypalon (trademark) rubber, etc.), butyl rubber, isoprene rubber, etc. are preferable.

[0049] The sealing member 12 has a shape (for example, a disk shape such as a disc shape) corresponding to the shape of the opening of the case 11. The sealing member 12 has through holes for passing the rod-shaped portions 17A and 17B through. The shape and size of the through holes may be determined appropriately depending on the shape and size of the rod-shaped portions 17A and 17B.

[0050] The capacitor element 10 will now be described.

[0051] Capacitor element 10 includes, for example, a wound body as shown in Fig. 2. The wound body includes anode 21 having a dielectric layer, cathode 22, and separator 23 interposed therebetween. In capacitor element 10, lead 14A is connected to anode 21, and lead 14B is connected to cathode 22.

[0052] The anode 21 and the cathode 22 are wound with a separator 23 interposed therebetween. The outermost periphery of the wound body is fixed with a stop tape 24. Note that Fig. 2 shows a state in which the outermost periphery of the wound body is not fixed and is partly unfolded.

[0053] For example, a metal foil having a roughened surface is used as the anode 21. The type of metal constituting the metal foil is not particularly limited, but it is preferable to use a valve metal such as aluminum, tantalum, or niobium, or an alloy containing a valve metal, in terms of ease of forming a dielectric layer.

[0054] The metal foil surface can be roughened by a known method. By roughening, a plurality of projections and recesses are formed on the surface of the metal foil. The roughening is preferably performed, for example, by etching the metal foil. The etching may be performed, for example, by DC electrolysis or AC electrolysis.

[0055] The dielectric layer is formed on the surface of the anode 21. Specifically, since the dielectric layer is formed on the surface of the roughened metal foil, it is formed along the inner wall surfaces of holes and depressions (pits) on the surface of the anode 21.

[0056] The method for forming the dielectric layer is not particularly limited, but the dielectric layer can be formed by subjecting a metal foil to a chemical conversion treatment. The chemical conversion treatment may be performed, for example, by immersing the metal foil in a chemical conversion solution such as an ammonium adipate solution. In the chemical conversion treatment, a voltage may be applied to the metal foil while it is immersed in the chemical conversion solution, if necessary.

[0057] For example, a metal foil is used for the cathode 22. Although the type of metal is not particularly limited, it is preferable to use a valve metal such as aluminum, tantalum, or niobium, or an alloy containing a valve metal. The cathode 22 may be subjected to surface roughening and / or chemical conversion treatment as necessary. The surface roughening and chemical conversion treatment can be performed, for example, by the method described for the anode 21.

[0058] The separator 23 is not particularly limited, and may be made of, for example, a nonwoven fabric containing fibers of cellulose, polyethylene terephthalate, vinylon, or polyamide (for example, aliphatic polyamide, aromatic polyamide such as aramid).

[0059] The wound body can be produced by a known method. When forming the wound body, the leads may be wound while being wound, so that leads 14A and 14B are planted from the wound body as shown in FIG.

[0060] The capacitor element 10 includes an electrolytic solution. The electrolytic solution may be a non-aqueous solvent or a mixture of a non-aqueous solvent and an ionic substance (solute, for example, an organic salt) dissolved therein. The non-aqueous solvent may be an organic solvent or an ionic liquid. Examples of the non-aqueous solvent that can be used include ethylene glycol, propylene glycol, sulfolane, γ-butyrolactone, and N-methylacetamide. Examples of the organic salt include trimethylamine maleate, triethylamine borodisalicylate, triethylamine phthalate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, and mono-1,3-dimethyl-2-ethylimidazolinium phthalate.

[0061] Capacitor element 10 may include a solid electrolyte layer covering at least a portion of the surface of the dielectric layer.

[0062] The solid electrolyte layer includes, for example, a manganese compound and a conductive polymer. Examples of the conductive polymer that can be used include polypyrrole, polythiophene, polyaniline, and derivatives thereof. The solid electrolyte layer can be formed, for example, by chemically polymerizing and / or electrolytically polymerizing a raw material monomer on the dielectric layer. Alternatively, the solid electrolyte layer can be formed by applying a solution in which the conductive polymer is dissolved or a dispersion in which the conductive polymer is dispersed to the dielectric layer.

[0063] The case 11 is made of a material such as aluminum, stainless steel, copper, iron, brass, or an alloy of these metals.

[0064] (First Modification of the First Embodiment) Electrolytic capacitor 1B shown in Fig. 3 has the same structure as that of the first embodiment, except that the tips of rod-shaped portions 17A, 17B of tab portions 16A, 16B are not embedded in molded resin layer 13. In this modification, lead-inside connection portions 175A, 175B and subsequent drawn-out portions 15A, 15B can also be sufficiently separated from the boundary between sealing material 12 and molded resin layer 13. Note that in Fig. 3, the same reference numerals are used to designate the same components as those in the first embodiment shown in Fig. 1.

[0065] The molded resin layer 13 covers the entire outer surface of the sealing member 12. On the other hand, the tips of the rod-shaped portions 17A, 17B and the lead internal connection portions 175A, 175B are not embedded in the molded resin layer 13 and are exposed to the outside. In such exposed portions, capillary action that promotes the electrolyte component to creep up does not occur. In addition, the exposed portions are constantly exposed to the outside air and are prone to drying. As a result, the electrolyte component is further prevented from accumulating between the leads.

[0066] Again, the distance D is preferably 5% or more of the maximum thickness T of the molded resin layer 13. In this case, it is desirable to set the distance D so that the tips of the rod-shaped portions 17A and 17B do not protrude from the mounting surface 13S of the molded resin layer 13.

[0067] When the elongated grooves 13A, 13B are provided on the mounting surface 13S of the molded resin layer 13, it is preferable to increase the depth of the grooves 13A, 13B at the locations where the tips of the rod-shaped portions 17A, 17B protrude from the molded resin layer 13. This allows the lead internal connection portions 175A, 175B and the subsequent drawn-out portions 15A, 15B to be accommodated in the grooves 13A, 13B. This makes it possible to prevent the drawn-out portions 15A, 15B from protruding from the mounting surface 13S.

[0068] (Second Modification of the First Embodiment) In electrolytic capacitor 1C shown in Fig. 4, the entire portions of rod-shaped portions 17A, 17B that protrude from the outer surface of sealing material 12 are exposed and not covered with molded resin layer 13. Except for this, the electrolytic capacitor 1C has the same structure as the first embodiment. Again, distance D is preferably 5% or more of maximum thickness T of molded resin layer 13. Note that in Fig. 4, the same reference numerals are used to designate the same components as those in the first embodiment shown in Fig. 1.

[0069] Around the through-hole of the sealing member 12 from which the rod-shaped parts 17A and 17B protrude, an area that is not covered by the molded resin layer 13 is formed so as to surround the through-hole. For example, a cylindrical through-hole is formed in the molded resin layer 13, through which a part of the rod-shaped parts 17A and 17B is inserted. In this case, the boundary between the molded resin layer 13 and the sealing member 12 is not formed at least in a part around the rod-shaped parts 17A and 17B protruding from the sealing member 12, and the outer surface of the sealing member 12 is slightly exposed. Therefore, around the rod-shaped parts 17A and 17B protruding from the sealing member 12, the boundary between the sealing member 12 and the molded resin layer 13 becomes discontinuous. In addition, the capillary phenomenon that promotes the creeping up of the electrolyte component does not occur in the rod-shaped parts 17A and 17B protruding from the sealing member 12, and the tip parts of the rod-shaped parts 17A and 17B are always exposed to the outside air and are easily dried. As a result, corrosion of the leads due to the electrolyte components is further suppressed.

[0070] Note that the lead is prevented from coming into contact with components of the electrolyte solution if at least one of the anode lead and the cathode lead protrudes from the outer surface of the sealing member as shown in Fig. 1, 3, or 4. Alternatively, one of the anode lead and the cathode lead may have any of the configurations shown in Fig. 1, 3, or 4, and the other may have any of the other configurations shown in Fig. 1, 3, or 4.

[0071] Second embodiment The electrolytic capacitor according to the second embodiment of the present disclosure includes a capacitor element including a pair of electrodes, an electrolytic solution interposed between the pair of electrodes, a case for accommodating the capacitor element and the electrolytic solution, a sealing member, a molded resin layer covering the sealing member, and a pair of leads penetrating the sealing member and the molded resin layer. The case has an opening. The sealing member seals the opening of the case. The pair of leads are electrically connected to the pair of electrodes, respectively. At least one of the pair of leads has an insulating region covered with an electrical insulating layer. The electrical insulating layer is provided between at least one of the pair of leads and at least one of the sealing member and the molded resin layer. It is sufficient that the electrical insulating layer is formed in at least a part of the region where the leads penetrate the sealing member and the molded resin layer.

[0072] One of the pair of electrodes is an anode and the other is a cathode. The anode has a dielectric layer on its surface. One of the pair of leads is an anode lead that is electrically connected to the anode, and the other is a cathode lead that is electrically connected to the cathode.

[0073] By providing the insulating region (electrical insulating layer), even if the electrolyte accumulates inside the sealing member or at the boundary between the sealing member and the molded resin layer, contact between the lead and the electrolyte is suppressed. Therefore, even if the chlorine component contained in the sealing member dissolves into the electrolyte, corrosion of the lead can be suppressed. Note that the electrolyte accumulates means that the components contained in the electrolyte (for example, a solvent or a solution in which an electrolyte salt is dissolved) accumulate.

[0074] The lead may come into contact with the stagnant electrolyte not only in the area where the lead penetrates the sealing material but also in the area where the lead penetrates the molded resin layer. Therefore, if an electrical insulating layer is formed between the lead and the sealing material and / or the molded resin layer (at least in a part of the area where the lead penetrates the sealing material and the molded resin layer), the effect of suppressing corrosion of the lead can be obtained.

[0075] In particular, since the electrolyte is likely to remain at the boundary between the sealing member and the molded resin layer, it is preferable that the electrical insulating layer is provided so that at least one of the pair of leads does not contact the boundary between the sealing member and the molded resin layer (i.e., the lead does not face the boundary). In this case, the effect of providing the insulating region can be further enhanced. Furthermore, it is more preferable that the electrical insulating layer is provided across the boundary between the sealing member and the molded resin layer.

[0076] In addition, if a voltage is applied to the electrolytic capacitor in a state where the pair of leads are in contact with the electrolyte remaining at the boundary between the sealing material and the molded resin layer, the corrosion of the leads (particularly the anode lead) will progress. By providing an electrical insulating layer so that at least one of the pair of leads does not come into contact with the boundary between the sealing material and the molded resin layer, the progress of such corrosion of the leads is suppressed. In order to further enhance the effect of suppressing the progress of such corrosion of the leads, it is preferable that an insulating region is provided on both of the pair of leads. In addition, in such a state, the metal (e.g., aluminum or tin) constituting the anode lead is likely to dissolve out of the anode lead. Therefore, an insulating region may be provided only on the anode lead.

[0077] The electrical insulating layer preferably has excellent corrosion resistance against the electrolyte or a solvent containing a chlorine component, so that the effect of providing the insulating region can be maintained for a long period of time.

[0078] The electrolytic capacitor according to the second embodiment of the present disclosure will be described in detail below with reference to the drawings, but the present disclosure is not limited thereto.

[0079] 7 includes a capacitor element 10 including an anode foil 21 (see FIG. 2) and a cathode foil 22 (see FIG. 2), an electrolyte (not shown) interposed between the anode foil 21 and the cathode foil 22, and a cylindrical case 11 with an opening and a bottom that contains the capacitor element 10 and the electrolyte. Examples of materials for case 11 include metals such as aluminum, stainless steel, copper, iron, and brass, or alloys of these metals.

[0080] The electrolytic capacitor 2A includes a sealing member 12 that seals the opening of the case 11, and a molded resin layer 13 that covers the sealing member 12. The molded resin layer 13 is provided so as to cover the opening of the case 11 together with the main surface of the sealing member 12 that is disposed on the outside of the case 11. After the capacitor element 10 is accommodated in the opening of the case 11, the opening is sealed with the sealing member 12 and the molded resin layer 13. The vicinity of the opening end of the case 11 is drawn toward the sealing member 12, and the opening end of the case 11 is crimped inward. As a result, the sealing member 12 is fixed to the opening of the case 11, and the case 11 is sealed with the sealing member 12. The provision of the molded resin layer 13 suppresses deterioration of the sealing member 12 due to oxidation and the like, and further improves the sealing property of the electrolytic capacitor 2A.

[0081] 7, it is preferable that the molded resin layer 13 further covers at least a part of the side surface continuing to the opening of the case 11. This can further improve the sealing performance of the electrolytic capacitor. Note that in this embodiment, the molded resin layer 13 may be partially not bonded to the case 11 and the sealing member 12.

[0082] The mold resin layer 13 may have the same structure and be made of the same material as in the first embodiment.

[0083] Electrolytic capacitor 2A has a pair of leads 14A, 14B that are electrically connected to anode foil 21 and cathode foil 22, respectively, included in capacitor element 10, and that penetrate sealing material 12 and molded resin layer 13. When the electrolytic capacitor is mounted on a substrate, capacitor element 10 is electrically connected to a terminal on the substrate via leads 14A, 14B.

[0084] Leads 14A and 14B have tab portions 16A and 16B connected to anode foil 21 and cathode foil 22, respectively, and lead portions 15A and 15B connected to tab portions 16A and 16B, respectively. Lead portions 15A and 15B and tab portions 16A and 16B are connected by welding or the like. Lead portions 15A and 15B include a metal such as iron, copper, nickel, or tin. Tab portions 16A and 16B include aluminum, for example.

[0085] The tab portions 16A and 16B each have a rod-shaped portion 17A or 17B and a flat portion 18A or 18B. The rod-shaped portion 17A or 17B and the flat portion 18A or 18B may be integrated as long as they are electrically connected to each other. For example, a flat portion is formed by rolling one end of a rod-shaped body, and an area that is not rolled remains as a rod-shaped portion, thereby forming a tab portion in which the flat portion and the rod-shaped portion are integrated.

[0086] In this embodiment, rod-shaped portions 17A and 17B each include a portion disposed within sealing material 12. Lead portions 15A and 15B extend from the tip ends of rod-shaped portions 17A and 17B, respectively. Rod-shaped portions 17A and 17B are connected to capacitor element 10 via flat portions 18A and 18B, respectively. The presence of flat portions 18A and 18B facilitates connection between leads 14A and 14B and the capacitor element.

[0087] The shape of the lead portions 15A and 15B is not particularly limited, and may be, for example, a wire shape or a ribbon shape. The shape of the rod-shaped portions 17A and 17B is not particularly limited, and may be, for example, a round rod shape (for example, a rod shape having a circular or elliptical cross section) or a square rod shape (for example, a rod shape having a polygonal cross section).

[0088] The leads 14A and 14B have insulating regions covered with electrical insulating layers 19A and 19B. The electrical insulating layers 19A and 19B are provided between the leads 14A and 14B and the sealing material 12 and the molded resin layer 13. By providing the electrical insulating layers 19A and 19B, corrosion of the leads can be suppressed even if the chlorine component contained in the sealing material 12 dissolves into the electrolyte remaining inside the sealing material 12 or at the boundary between the sealing material 12 and the molded resin layer 13.

[0089] 7, the electrical insulating layers 19A, 19B are preferably provided so that the leads 14A, 14B do not come into contact with the boundary between the sealing material 12 and the molded resin layer 13. By providing such electrical insulating layers 19A, 19B, it is possible to prevent the leads 14A, 14B from coming into contact with the electrolyte remaining at the boundary between the sealing material 12 and the molded resin layer 13. It is possible to prevent the progress of corrosion of the leads 14A, 14B (particularly the lead 14A on the anode side) when a voltage is applied to the electrolytic capacitor with the leads 14A, 14B in contact with the electrolyte.

[0090] 7, it is more preferable that the electrical insulating layers 19A, 19B are provided across the boundary between the sealing material 12 and the molded resin layer 13. In this case, the effect of preventing the leads 14A, 14B from coming into contact with the electrolyte remaining at the boundary between the sealing material 12 and the molded resin layer 13 can be further enhanced.

[0091] It is preferable that the electrical insulating layers 19A and 19B have excellent corrosion resistance against the electrolyte or a solvent containing a chlorine component, in which case the effect of providing the insulating regions can be maintained for a long period of time.

[0092] The thickness of the electrical insulating layers 19A and 19B is, for example, not less than 0.01 mm and not more than 1.00 mm.

[0093] When the lead portions 15A, 15B contain a transition metal, the ends of the lead portions 15A, 15B and the rod-shaped portions 17A, 17B are melted together during welding of the lead portions 15A, 15B and the rod-shaped portions 17A, 17B, and the transition metal is exposed on the surface of the joint. Therefore, when the joint comes into contact with the electrolyte remaining at the boundary between the sealing material 12 and the molded resin layer 13, corrosion is likely to progress at the joint (particularly the joint on the anode side), and the lead is likely to break at the joint. Therefore, as shown in FIG. 7, it is preferable that at least the joint between the tab portions 16A, 16B (rod-shaped portions 17A, 17B) and the lead portions 15A, 15B is covered with the electrical insulating layers 19A, 19B. In other words, it is preferable that the insulating region is provided in the region extending from the rod-shaped portions 17A, 17B of the leads 14A, 14B to the lead portions 15A, 15B. Covering the joint with an electrical insulating layer can suppress the progression of corrosion at the joint and the associated breakage at the joint. As shown in Fig. 1, when the joint is located near the above-mentioned boundary, it is likely to come into contact with the electrolyte remaining at the boundary, so that the effect of covering the joint with electrical insulating layers 19A and 19B shown in Fig. 7 is remarkable.

[0094] In this embodiment, as shown in FIG. 7, at least a portion of the joint between the tab portions 16A, 16B (rod-shaped portions 17A, 17B) and the pull-out portions 15A, 15B is located on the sealing material 12 side of the boundary between the sealing material 12 and the molded resin layer 13, but at least a portion of the joint may be located on the molded resin layer 13 side of the boundary.

[0095] It is preferable that the distances t1a, t1b of the insulating region extending from the boundary between the sealing material 12 and the molded resin layer 13 toward the molded resin layer 13 side be 10% or more of the thickness T1 of the molded resin layer 13. In this case, the sealing performance of the electrolytic capacitor can be further improved.

[0096] In this embodiment, the distances t1a and t1b of the insulating regions are the distances that the electrical insulating layers 19A and 19B extend from the boundary surface between the sealing material 12 and the molded resin layer 13 toward the molded resin layer 13 in a direction perpendicular to the boundary surface. The thickness T1 of the molded resin layer 13 is the thickness in the axial direction of the case 11 (the X direction in FIG. 1), and is the thickness of a region of the molded resin layer 13 where grooves 13A and 13B, described later, are not provided.

[0097] It is preferable that the distances t2a, t2b of the insulating region extending from the boundary between the sealing material 12 and the molded resin layer 13 toward the sealing material 12 side be 10% or more of the thickness T2 of the sealing material 12. In this case, the sealing performance of the electrolytic capacitor can be further improved.

[0098] In this embodiment, the distances t2a and t2b of the insulating regions are the distances that the electrical insulating layers 19A and 19B extend from the boundary surface between the sealing material 12 and the molded resin layer 13 toward the sealing material 12 in a direction perpendicular to the boundary surface. The thickness T2 of the sealing material 12 is the thickness in the axial direction of the case 11 (the X direction in FIG. 1).

[0099] In this embodiment, the insulating region is provided on both the lead 14A and the lead 14B, but the insulating region may be provided on one of the lead 14A and the lead 14B.

[0100] (Modification of the second embodiment) In the second embodiment, the electrical insulating layers 19A and 19B shown in Fig. 7 are provided, but the electrical insulating layers 29A and 29B shown in Fig. 8 may be provided. By providing the electrical insulating layers 29A and 29B, contact with the electrolyte can be suppressed over the entire region where the leads 14A and 14B penetrate the sealing material 12 and the molded resin layer 13.

[0101] One end of each of the electrical insulating layers 29A and 29B is exposed from the main surface of the sealing material 12 opposite to the mold resin layer 13. In this case, the effect of providing the insulating region can be further enhanced.

[0102] The other ends of the electrical insulating layers 29A, 29B are exposed from the mounting surface 13S side of the molded resin layer 13. In this case, the effect of providing the insulating region can be further enhanced. However, in order to improve mountability, it is preferable that the electrical insulating layers 29A, 29B are not provided in the portion where the leads 14A, 14B are mounted.

[0103] The electrical insulating layers 19A, 19B, 29A, and 29B preferably include at least one of an insulating resin layer and an insulating ceramic layer, which provides an electrical insulating layer having excellent electrical insulation and corrosion resistance against the electrolyte (a solvent containing a chlorine component).

[0104] The insulating resin layer preferably contains a cured product of a curable resin composition, a thermoplastic resin, or a composition containing the same. As the curable resin, for example, those exemplified as materials that can be used for the molded resin layer, such as a thermosetting resin, can be used. The curable resin composition may contain a filler, a curing agent, etc. in addition to the curable resin.

[0105] Examples of the thermosetting resin that can be used include phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester, alkyd resin, polyurethane, thermosetting polyimide, etc. Among them, the thermosetting resin is preferably phenol resin, epoxy resin, or thermosetting polyimide.

[0106] Examples of the thermoplastic resin that can be used include fluororesin (e.g., polytetrafluoroethylene), polyamideimide, polyimide, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, ABS resin, AS resin, acrylic resin, etc. Among them, the thermoplastic resin is preferably fluororesin, polyamideimide, or polyimide.

[0107] The insulating resin layer may be formed by applying a thermosetting resin composition to a predetermined location of the lead and then curing the composition, or by applying a thermoplastic resin (composition) to a predetermined location of the lead. The insulating resin layer may also be formed by attaching an insulating resin tape to a predetermined location of the lead.

[0108] The insulating ceramic layer preferably contains silica, metal oxide, carbide, boride, and coupling agent. Silica includes, for example, natural crystalline silica, natural amorphous silica, synthetic crystalline silica, synthetic amorphous silica, and the like. Among them, silica preferably contains synthetic amorphous silica. Metal oxide includes, for example, oxide containing aluminum, oxide containing titanium, oxide containing tantalum, and the like. Carbide includes, for example, silicon carbide, titanium carbide, boron carbide, and the like. Boride includes, for example, aluminum diboride, titanium diboride, and the like. Coupling agent includes, for example, silane coupling agent, titanate coupling agent, and the like.

[0109] The insulating ceramic layer is formed, for example, by attaching ceramics to a predetermined location of the lead by an aerosol deposition method, by attaching a tape containing ceramics, or by applying a paint containing ceramics.

[0110] The electrical insulating layer may be formed before or after the leads are inserted into the sealing material.

[0111] An example of an electrolytic capacitor in which the electrical insulating layer is formed before the leads are inserted into the sealing material is shown in Figures 9 and 10. Figures 9 and 10 are cross-sectional views of a main part showing the vicinity of the boundary between the sealing material and the molded resin layer in the electrolytic capacitor.

[0112] In the case of the electrolytic capacitor shown in Fig. 9, for example, electrical insulating layers 39A and 39B shown in Fig. 9 are provided. Then, rod-shaped portions 17A and 17B are inserted into sealing member 12 so that joints between lead portions 15A and 15B and rod-shaped portions 17A and 17B are positioned within holes in sealing member 12, and then molded resin layer 13 is formed.

[0113] In the case of the electrolytic capacitor shown in Fig. 10, for example, electrical insulating layers 49A and 49B shown in Fig. 10 are provided. Then, rod-shaped portions 17A and 17B are inserted into sealing member 12 so that the joints between lead portions 15A and 15B and rod-shaped portions 17A and 17B are positioned outside the holes of sealing member 12, and then molded resin layer 13 is formed.

[0114] 11 and 12 show examples of electrolytic capacitors in which the electrical insulating layer is formed after the leads are inserted into the sealing material. Figures 11 and 12 are cross-sectional views of essential parts showing the vicinity of the boundary between the sealing material and the molded resin layer in the electrolytic capacitor.

[0115] 11, for example, rod-shaped portions 17A, 17B are inserted into sealing material 12 so that joints between lead portions 15A, 15B and rod-shaped portions 17A, 17B are positioned within holes in sealing material 12. Thereafter, electrical insulating layers 59A, 59B shown in FIG. 11 are provided, and then molded resin layer 13 is formed.

[0116] 12, for example, rod-shaped portions 17A, 17B are inserted into sealing material 12 so that joints between lead portions 15A, 15B and rod-shaped portions 17A, 17B are positioned outside the holes of sealing material 12. Thereafter, electrical insulating layers 69A, 69B shown in FIG. 12 are provided, and then molded resin layer 13 is formed.

[0117] In this embodiment, the electrical insulation layer is not limited to the electrical insulation layer shown in Figs. 9 to 12. In this embodiment, if the electrical insulation layer is provided between the lead and the sealing material and / or the molded resin layer, the effect of suppressing corrosion of the lead can be obtained. The electrical insulation layer may be provided between the lead and the sealing material and the molded resin layer (for example, across the boundary between the sealing material and the molded resin layer). In addition, the electrical insulation layer may be provided only between the lead and the sealing material (the region where the lead penetrates the sealing material) or only between the lead and the molded resin layer (the region where the lead penetrates the molded resin).

[0118] The lead-out portions 15A and 15B have portions that are led out from the mounting surface 13S side of the molded resin layer 13 to the outside, and these portions are disposed along the mounting surface 13S of the molded resin layer 13.

[0119] 7, elongated grooves 13A and 13B for accommodating portions (extended portions 15A and 15B) of the leads 14A and 14B extended from the molded resin layer 13 to the outside may be provided on the mounting surface 13S of the molded resin layer 13. By accommodating the extended portions 15A and 15B in the grooves 13A and 13B, the extended portions 15A and 15B can be stably fixed and positioned near the mounting surface 13S.

[0120] The bottom surfaces 13a, 13b of the grooves 13A, 13B are inclined so that the depth of the grooves 13A, 13B gradually increases from one end where the leads 14A, 14B of the grooves 13A, 13B are drawn out from the molded resin layer 13 to the other end. When the drawn-out portions 15A, 15B are bent so as to be substantially parallel to the mounting surface 13S, a force acts on the drawn-out portions 15A, 15B to return to their original shape. By inclining the bottom surfaces of the grooves 13A, 13B in the above manner in consideration of this point, the drawn-out portions 15A, 15B do not excessively protrude from the mounting surface 13S, and the drawn-out portions 15A, 15B can be accommodated in the grooves 13A, 13B. The inclination angle of the bottom surfaces of the grooves 13A, 13B with respect to the mounting surface 13S is, for example, 3° or more and 30° or less.

[0121] In this embodiment, the bottom surfaces of the grooves 13A and 13B are inclined, but the depths of the grooves 13A and 13B may be constant without inclining the bottom surfaces of the grooves 13A and 13B.

[0122] The sealing member 12 may have the same structure and be made of the same material as in the first embodiment.

[0123] The capacitor element 10 is similar to that of the first embodiment, and therefore a description thereof will be omitted. In this embodiment, the conductivity of the electrolyte may be low.

[0124] The electrolyte contained in the case may contain a solvent capable of dissolving the chlorine component contained in the sealing material. Therefore, even if the amount of electrolyte (solvent) in the case is small, the lead may corrode. By providing an electrical insulating layer, it is possible to obtain an effect of suppressing such corrosion of the lead.

[0125] Third embodiment The molded resin layer is usually formed in close contact with the sealing material. However, the degree of expansion (linear expansion coefficient) of the molded resin layer and the sealing material when the temperature rises is significantly different. Therefore, stress is concentrated near the boundary between the molded resin layer and the sealing material, which may cause cracks in the molded resin layer and reduce the sealing performance of the electrolytic capacitor.

[0126] An electrolytic capacitor according to a third embodiment of the present disclosure includes a capacitor element including a pair of electrodes, a case that houses the capacitor element, a sealing member, a molded resin layer that covers the sealing member, and a pair of leads that penetrate the sealing member and the molded resin layer. The case has an opening. The sealing member seals the opening of the case. The pair of leads are electrically connected to the pair of electrodes, respectively. A gap is provided between the sealing member and the molded resin layer.

[0127] By providing the above gap, even if the degree of expansion (linear expansion coefficient) during temperature rise differs greatly between the molded resin layer and the sealing material, stress is less likely to concentrate near the boundary between the molded resin layer and the sealing material. By mitigating the concentration of stress, it is possible to suppress the occurrence of cracks in the molded resin layer. Therefore, it is possible to suppress the deterioration of the sealing property of the electrolytic capacitor caused by the occurrence of cracks in the molded resin layer.

[0128] The gap is preferably a minute gap formed by the mold resin layer not being in close contact (bonded) with the sealing material. A minute gap is advantageous for miniaturizing the electrolytic capacitor. The minute gap can be formed by the method described below.

[0129] The molded resin layer preferably further covers at least a part of the side surface continuing to the opening of the case. In this case, the sealing performance of the electrolytic capacitor can be further improved. The molded resin layer preferably adheres to the case in a region facing the case. In this case, the molded resin layer covering the sealing member can be more firmly fixed.

[0130] When the electrolytic capacitor has an electrolytic solution, it is preferable that a film of a component contained in the electrolytic solution is formed on the surface (exposed surface) of the sealing member exposed to the gap. That is, it is preferable that at least a part of the exposed surface is covered with a film of a component contained in the electrolytic solution. By covering the exposed surface of the sealing member with a film of a component contained in the electrolytic solution, contact between the sealing member and oxygen is suppressed even when the molded resin layer contains a resin component that is relatively easy for oxygen to permeate. Therefore, even in a high-temperature environment, deterioration of the sealing member due to contact between the oxygen that has permeated the molded resin layer and the sealing member is suppressed.

[0131] When the electrolytic capacitor includes an electrolytic solution interposed between a pair of electrodes and the electrolytic solution is housed in a case, the film of the components contained in the electrolytic solution may be formed by the components of the electrolytic solution housed in the case permeating the sealing member and staying in the gap between the sealing member and the molded resin layer. When the electrolytic capacitor includes an electrolytic solution interposed between a pair of electrodes and the electrolytic solution is housed in a case, the components (e.g., solvent) contained in the electrolytic solution relatively easily permeate the sealing member, but do not easily permeate the molded resin layer. Therefore, by providing a gap between the sealing member and the molded resin layer, the components of the electrolytic solution that have permeated the sealing member tend to stay in the gap between the sealing member and the molded resin layer. Therefore, a film of the components of the electrolytic solution can be efficiently formed on the exposed surface of the sealing member.

[0132] One of the pair of electrodes is an anode, and the other is a cathode. The anode has a dielectric layer on its surface. One of the pair of leads is an anode lead electrically connected to the anode, and the other is a cathode lead electrically connected to the cathode. The pair of leads penetrating the sealing member and the molded resin layer are exposed to a gap provided between the sealing member and the molded resin layer. Therefore, it is preferable that at least one of the pair of leads has an insulating region covered with an electrical insulating layer. It is more preferable that the insulating region is provided at least across the gap. That is, it is more preferable that the insulating region is provided so as to pass (straddle) the gap from the portion where the lead penetrates the sealing member to the portion where the lead penetrates the molded resin layer.

[0133] By providing the insulating region, even if a film of the components contained in the electrolyte is formed (the components contained in the electrolyte are retained) in the gap between the sealing material and the molded resin layer, contact between the pair of leads and the components of the electrolyte is suppressed. If a voltage is applied to the electrolytic capacitor in a state in which the pair of leads are in contact with the components of the electrolyte, corrosion of the leads (particularly the anode lead) progresses. By providing the insulating region, the progress of such corrosion is suppressed.

[0134] Even if the insulating region is provided on only one of the pair of leads, it is possible to suppress the progress of corrosion as described above. However, in order to further enhance the effect of suppressing the progress of lead corrosion, it is preferable to provide the insulating region on both of the pair of leads.

[0135] The electrical insulating layer preferably has excellent electrolyte resistance. In this case, the effect of providing the insulating region can be maintained for a long period of time. The electrical insulating layer preferably includes at least one of an insulating resin layer and an insulating ceramic layer, for example.

[0136] The electrolytic capacitor may include an electrolytic solution interposed between a pair of electrodes, and the electrolytic solution may be contained in a case. The electrolytic capacitor may include a solid electrolyte layer covering at least a portion of the surface of the dielectric layer. The electrolytic capacitor may include both the electrolytic solution and the solid electrolyte layer.

[0137] Hereinafter, the electrolytic capacitor according to the third embodiment of the present disclosure will be described in detail with reference to the drawings, but the present disclosure is not limited thereto.

[0138] 13 includes a capacitor element 10 including an anode foil 21 (see FIG. 2) and a cathode foil 22 (see FIG. 2), an electrolyte (not shown) interposed between the anode foil 21 and the cathode foil 22, and a cylindrical case 11 with an opening and a bottom that contains the capacitor element 10 and the electrolyte. Examples of materials for case 11 include metals such as aluminum, stainless steel, copper, iron, and brass, or alloys of these metals.

[0139] The electrolytic capacitor 3A includes a sealing member 12 that seals the opening of the case 11, and a molded resin layer 13 that covers the sealing member 12. The molded resin layer 13 is provided so as to cover the opening of the case 11 together with the main surface of the sealing member 12 that is disposed on the outside of the case 11. After the capacitor element 10 is accommodated in the opening of the case 11, the opening is sealed with the sealing member 12 and the molded resin layer 13. The vicinity of the opening end of the case 11 is drawn toward the sealing member 12, and the opening end of the case 11 is crimped inward. As a result, the sealing member 12 is fixed to the opening of the case 11, and the case 11 is sealed with the sealing member 12. By providing the molded resin layer 13, the sealing property of the electrolytic capacitor 3A is further improved.

[0140] The molded resin layer 13 is not bonded to the sealing material 12 in the region facing the sealing material 12, and a minute gap 20 is formed between the molded resin layer 13 and the sealing material 12. By providing the gap 20, even if the degree of expansion (linear expansion coefficient) during temperature rise differs greatly between the molded resin layer 13 and the sealing material 12, stress is less likely to concentrate near the boundary between the molded resin layer 13 and the sealing material 12. By mitigating the stress concentration, it is possible to suppress the occurrence of cracks in the molded resin layer 13.

[0141] 13, it is preferable that molded resin layer 13 further covers at least a part of the side surface continuing to the opening of case 11. This can further improve the sealing performance of electrolytic capacitor 3A.

[0142] The molded resin layer 13 is adhered to the case 11 in a region facing the case 11. This allows the molded resin layer 13 covering the sealing material 12 to be firmly fixed. In this embodiment, it is sufficient that the molded resin layer 13 is partially adhered to the case 11 in the region facing the case 11, and there may be some portions where the molded resin layer 13 is not adhered.

[0143] The mold resin layer 13 may have the same structure and be made of the same material as in the first embodiment.

[0144] One method for providing the gap 20 between the sealing member 12 and the molded resin layer 13 is, for example, to apply a release agent to a predetermined region of the sealing member 12 (the region covered by the molded resin layer 13) when forming the molded resin layer 13. This makes it possible to easily form a minute gap by preventing the molded resin layer 13 from adhering to the sealing member 12. For example, a silicone-based or fluorine-based release agent is used as the release agent.

[0145] It is preferable that a film (not shown) of a component contained in the electrolyte is formed on the surface (exposed surface) of the sealing member 12 exposed to the gap 20. For example, by allowing the component of the electrolyte that has permeated the sealing member 12 to remain in the gap 20, a film of the component contained in the electrolyte can be formed so as to cover at least a portion of the exposed surface of the sealing member 12.

[0146] Because the exposed surface of the sealing member 12 is covered with a film of a component contained in the electrolyte, contact between the sealing member 12 and oxygen is suppressed even if external oxygen permeates through the molded resin layer 13 and reaches the gap 20. Therefore, deterioration of the sealing member 12 due to contact between oxygen and the sealing member 12 is suppressed even in a high-temperature environment.

[0147] The electrolytic capacitor includes a pair of leads 14A, 14B that are electrically connected to anode foil 21 and cathode foil 22, respectively, included in capacitor element 10, and that penetrate sealing material 12 and molded resin layer 13. When the electrolytic capacitor is mounted on a substrate, capacitor element 10 is electrically connected to a terminal on the substrate via leads 14A, 14B.

[0148] Leads 14A and 14B have tab portions 16A and 16B connected to anode foil 21 and cathode foil 22, respectively, and lead portions 15A and 15B connected to tab portions 16A and 16B, respectively. Lead portions 15A and 15B and tab portions 16A and 16B are connected by welding or the like. Lead portions 15A and 15B include a metal such as iron, copper, nickel, or tin. Tab portions 16A and 16B include aluminum, for example.

[0149] The tab portions 16A and 16B each have a rod-shaped portion 17A or 17B and a flat portion 18A or 18B. The rod-shaped portion 17A or 17B and the flat portion 18A or 18B may be integrated as long as they are electrically connected to each other. For example, a flat portion is formed by rolling one end of a rod-shaped body, and an area that is not rolled remains as a rod-shaped portion, thereby forming a tab portion in which the flat portion and the rod-shaped portion are integrated.

[0150] Each of the rod-shaped portions 17A and 17B includes a portion that penetrates the sealing material 12. The shape of the rod-shaped portions 17A and 17B is not particularly limited, and may be a round rod (for example, a rod having a circular or elliptical cross section) or a square rod (for example, a rod having a polygonal cross section). The rod-shaped portions 17A and 17B are connected to the capacitor element 10 via the flat portions 18A and 18B, respectively. The flat portions 18A and 18B facilitate the connection between the leads 14A and 14B and the capacitor element.

[0151] Lead portions 15A and 15B each include a portion penetrating molded resin layer 13. The shape of lead portions 15A and 15B is not particularly limited, and may be, for example, wire-like or ribbon-like. Lead portions 15A and 15B extend from the tip ends of rod-shaped portions 17A and 17B, respectively.

[0152] Here, an example of an electrolytic capacitor in which a gap is formed in a state where the rod-shaped portion is inserted into a hole in a sealing member so that the joint between the drawn portion and the rod-shaped portion is located inside the hole in the sealing member is shown in Fig. 14. Fig. 14 is a cross-sectional view of a main portion showing the vicinity of the boundary between the sealing member and the molded resin layer in an electrolytic capacitor.

[0153] 14, rod-shaped portions 17A and 17B are inserted into holes in sealing material 12 so that joints between lead portions 15A and 15B and rod-shaped portions 17A and 17B are located within the holes in sealing material 12. Tips of rod-shaped portions 17A and 17B are exposed from sealing material 12 on the molded resin layer 13 side. A gap 30 is provided between the tips of rod-shaped portions 17A and 17B and sealing member 12, and between sealing member 12 and molded resin layer 13.

[0154] The gap 30 is formed, for example, by the following method: Rod-shaped portions 17A and 17B are inserted into holes in sealing material 12 so that the joints between lead portions 15A and 15B and rod-shaped portions 17A and 17B are positioned within the holes in sealing material 12. Thereafter, when molding mold resin layer 13, a release agent is applied to the tips of rod-shaped portions 17A and 17B and to predetermined regions of sealing material 12 (regions covered by mold resin layer 13).

[0155] 15 shows an example of an electrolytic capacitor in which a gap is formed in a state where the rod-shaped portion is inserted into a hole in a sealing material such that the joint between the drawn portion and the rod-shaped portion is located outside the hole in the sealing material. Fig. 15 is a cross-sectional view of a main portion showing the vicinity of the boundary between the sealing material and the molded resin layer in an electrolytic capacitor.

[0156] 15, rod-shaped portions 17A and 17B are inserted into holes in sealing material 12 so that joints between lead portions 15A and 15B and rod-shaped portions 17A and 17B are located outside the holes in sealing material 12. Tips of rod-shaped portions 17A and 17B are exposed from sealing material 12 on the molded resin layer 13 side. A gap 40 is provided between the tips of rod-shaped portions 17A and 17B and sealing member 12, and between sealing member 12 and molded resin layer 13.

[0157] The gap 40 is formed, for example, by the following method: Rod-shaped portions 17A and 17B are inserted into holes in sealing material 12 so that the joints between lead portions 15A and 15B and rod-shaped portions 17A and 17B are positioned within the holes in sealing material 12. Thereafter, when molding mold resin layer 13, a release agent is applied to the tips of rod-shaped portions 17A and 17B and to predetermined regions of sealing material 12 (regions covered by mold resin layer 13).

[0158] As shown in Figures 14 and 15, when the tip portions of the rod-shaped portions 17A, 17B are exposed from the sealing material 12 on the molded resin layer 13 side, a gap that is continuous with the gap formed between the sealing material 12 and the molded resin layer 13 may be further formed between the tip portions of the rod-shaped portions 17A, 17B and the molded resin layer 13.

[0159] (Modification of the third embodiment) Part of the leads 14A, 14B are exposed in a gap 20 provided between the sealing material 12 and the molded resin layer 13. Therefore, as shown in Fig. 16, the leads 14A, 14B preferably have insulating regions covered with electrical insulating layers 19A, 19B. The insulating regions are preferably provided at least across the gap 20. In other words, the insulating regions are preferably provided so as to pass through (straddle) the gap 20 from the portion where the leads 14A, 14B penetrate the sealing material 12 to the portion where the leads penetrate the molded resin layer 13.

[0160] By providing the insulating region, even if a film of a component contained in the electrolyte is formed on the surface of sealing member 12 exposed to gap 20 (if the component contained in the electrolyte remains in gap 20), contact between leads 14A, 14B and the component of the electrolyte is suppressed. This suppresses the progress of corrosion of leads 14A, 14B (particularly lead 14A on the anode side).

[0161] In FIG. 16, both the lead 14A and the lead 14B are provided with insulating regions, but it is also possible to provide an insulating region in only one of the lead 14A and the lead 14B.

[0162] When the lead portions 15A, 15B contain a transition metal, the ends of the lead portions 15A, 15B and the rod-shaped portions 17A, 17B are fused together during welding of the lead portions 15A, 15B and the rod-shaped portions 17A, 17B, and the transition metal is exposed on the surface of the joint. Therefore, when the joint comes into contact with the components of the electrolyte remaining in the gap 20, corrosion is likely to progress at the joint (particularly the joint on the anode side), and the lead is likely to break at the joint. Therefore, as shown in FIG. 16, it is preferable that at least the joint between the tab portions 16A, 16B (rod-shaped portions 17A, 17B) and the lead portions 15A, 15B is covered with an electrical insulating layer 19A, 19B. In other words, it is preferable that the insulating region is provided in the region extending from the rod-shaped portions 17A, 17B of the leads 14A, 14B to the lead portions 15A, 15B. Covering the joints with the electrical insulating layer can suppress the progression of corrosion at the joints and the associated breakage at the joints. As shown in Fig. 16, when the joints are located near the gap 20, they are likely to come into contact with the components of the electrolyte remaining in the gap 20, and therefore the effect of covering the joints with the electrical insulating layers 19A and 19B is remarkable.

[0163] Distances t1a, t1b that the insulating region extends from the boundary between the molded resin layer 13 and the gap 20 toward the molded resin layer 13 are preferably 10% or more of the thickness T1 of the molded resin layer 13. In this case, the effect of providing the insulating region can be further enhanced.

[0164] In this embodiment, the distances t1a and t1b of the insulating regions are the distances that the electrical insulating layers 19A and 19B extend from the boundary surface between the molded resin layer 13 and the gap 20 toward the molded resin layer 13 in a direction perpendicular to the boundary surface. The thickness T1 of the molded resin layer 13 is the thickness in the axial direction of the case 11 (the X direction in FIG. 16), and is the thickness of a region of the molded resin layer 13 where grooves 13A and 13B, described later, are not provided.

[0165] Distances t2a, t2b that the insulating region extends from the boundary between sealing material 12 and gap 20 toward sealing material 12 are preferably 10% or more of thickness T2 of sealing material 12. In this case, the effect of providing the insulating region can be further enhanced.

[0166] In this embodiment, distances t2a and t2b of the insulating regions are distances that the electrical insulating layers 19A and 19B extend toward the sealing member 12 side along a direction perpendicular to the boundary surface between the sealing member 12 and the gap 20. The thickness T2 of the sealing member 12 is the thickness in the axial direction of the case 11 (the X direction in FIG. 16).

[0167] From the viewpoint of maintaining the effect of providing the insulating region for a long period of time, it is preferable that the electrical insulating layers 19A and 19B include an insulating resin layer and / or an insulating ceramic layer having excellent electrolyte resistance. The thickness of the electrical insulating layers 19A and 19B may be, for example, 0.01 mm or more and 1.00 mm or less.

[0168] The insulating resin layer and the insulating ceramic layer can be made of the same structure and material as those in the second embodiment. The insulating ceramic layer can be formed, for example, by attaching ceramics to a predetermined location of the lead by an aerosol deposition method, by attaching a tape containing ceramics, or by applying a paint containing ceramics.

[0169] In Fig. 13, the lead-out portions 15A and 15B have portions that are drawn out from the mounting surface 13S side of the molded resin layer 13 to the outside. The portions are arranged along the mounting surface 13S of the molded resin layer 13. Here, as shown in Fig. 13, the mounting surface 13S of the molded resin layer 13 may be provided with elongated grooves 13A and 13B for accommodating the portions of the leads 14A and 14B that are drawn out from the molded resin layer 13 to the outside. By accommodating the lead-out portions 15A and 15B in the grooves 13A and 13B, the lead-out portions 15A and 15B can be stably fixed and arranged near the mounting surface 13S.

[0170] The bottom surfaces 13a, 13b of the grooves 13A, 13B are inclined so that the depth of the grooves 13A, 13B gradually increases from one end where the leads 14A, 14B of the grooves 13A, 13B are drawn out from the molded resin layer 13 to the other end. When the drawn-out portions 15A, 15B are bent so as to be substantially parallel to the mounting surface 13S, a force acts on the drawn-out portions 15A, 15B to return to their original shape. In consideration of this point, by inclining the bottom surfaces of the grooves 13A, 13B as described above, the drawn-out portions 15A, 15B do not excessively protrude from the mounting surface 13S, and the drawn-out portions 15A, 15B can be accommodated in the grooves 13A, 13B. The inclination angle of the bottom surfaces 13a, 13b of the grooves 13A, 13B with respect to the mounting surface 13S is, for example, 3° or more and 30° or less.

[0171] In this embodiment, the bottom surfaces of the grooves 13A and 13B are inclined, but the depths of the grooves 13A and 13B may be constant without inclining the bottom surfaces of the grooves 13A and 13B.

[0172] The sealing member 12 may have the same structure and be made of the same material as in the first embodiment.

[0173] The capacitor element 10 is similar to that in the first embodiment, and therefore the description thereof will be omitted. The capacitor element 10 may include an electrolytic solution and a solid electrolyte layer. [Industrial Applicability]

[0174] The present disclosure is useful in an electrolytic capacitor that contains an electrolyte solution in a case and is provided with a sealing material and a mold resin layer. [Explanation of symbols]

[0175] 1A,1B,1C,1D,2A,2B,3A,3B: Electrolytic capacitor 10: Capacitor element 11: Case 12: Sealing member 13: Mold resin layer 13S: Mounting surface 13A, 13B: Groove 13a, 13b: Bottom 14A, 14B: Lead 15A, 15B: Pull-out section 16A, 16B: Tab section 17A, 17B: Rod-shaped part 18A, 18B: Flat part 19A, 19B, 29A, 29B, 39A, 39B, 49A, 49B, 59A, 59B, 69A, 69B: Electrical insulating layer 20,30,40:Gap 21: Anode, anode foil 22: Cathode, cathode foil 23: Separator 24: Winding tape 175A, 175B: Lead internal connection

Claims

1. A capacitor element including a pair of electrodes; An electrolyte; a case that accommodates the capacitor element and the electrolyte and has an opening; a sealing member that seals the opening; a mold resin layer covering the sealing member; at least one pair of leads electrically connected to the pair of electrodes, respectively, and penetrating the sealing material and the mold resin layer; A gap is provided between the sealing material and the mold resin layer, An electrolytic capacitor, wherein a component contained in the electrolytic solution is present in the gap.

2. At least one of the pair of leads has an insulating region covered with an electrically insulating layer; The electrolytic capacitor according to claim 1 , wherein the insulating region is provided across at least the gap.

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