Electrolytic capacitor

Abstract

To reduce ESR of an electrolytic capacitor comprising a multilayer element.SOLUTION: An electrolytic capacitor comprises a multilayer element, and the multilayer element includes a plurality of units connected in parallel. Each of the plurality of units includes a plurality of capacitor elements connected in parallel. Each of the plurality of capacitor elements includes: a sheet-like positive electrode body including a positive electrode lead-out part and a positive electrode main part; a dielectric layer which is formed on a surface of the positive electrode main part; and a solid electrolyte covering at least a portion of the dielectric layer. Each of the plurality of units includes: a first positive electrode junction part where the positive electrode lead-out parts of the plurality of capacitor elements constituting the unit are overlapped and joined; a positive electrode sharing lead; and a second positive electrode junction part where the first positive electrode junction part and the positive electrode sharing lead are overlapped and joined.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to electrolytic capacitors. [Background technology]

[0002] Patent Document 1 proposes "a solid electrolytic capacitor in which two or more capacitor element laminate units, each of which is made by laminating at least two flat capacitor elements, are laminated and the electrodes are connected to each other."

[0003] Patent Document 2 proposes "a solid electrolytic capacitor comprising a capacitor element in which a rectangular anode body made of a valve action metal is separated along the short side into an anode portion and a cathode portion, and a dielectric oxide film layer, a solid electrolyte layer, and a cathode layer are sequentially laminated on the surface of the cathode portion; an anode terminal and a cathode terminal to which the anode portion and the cathode portion of the capacitor element are respectively connected and which are drawn out in opposite directions to the long side; and an insulating exterior resin covering the capacitor element with portions of the anode terminal and the cathode terminal exposed on the outer surface." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-138138 A [Patent Document 2] JP 2004-71745 A Summary of the Invention [Problem to be solved by the invention]

[0005] The market demands electrolytic capacitors with low ESR and high volumetric efficiency. In multilayer elements, low ESR has been achieved by connecting multiple capacitor elements in parallel. The more layers of the capacitor elements connected in parallel, the lower the ESR becomes.

[0006] However, as the current flowing through an electrolytic capacitor increases, the ESR must be lowered.On the other hand, there is also a strong demand for electrolytic capacitors to take up less space (improve volumetric efficiency), making it difficult to increase the number of layers in a capacitor element. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to an electrolytic capacitor comprising a laminated element, the laminated element comprising a plurality of units connected in parallel, each of the plurality of units comprising a plurality of capacitor elements connected in parallel, each of the plurality of capacitor elements comprising a sheet-shaped anode body having an anode lead and an anode main portion, a dielectric layer formed on a surface of the anode main portion, and a solid electrolyte covering at least a portion of the dielectric layer, each of the plurality of units comprising a first anode junction portion in which the anode lead portions of the plurality of capacitor elements constituting the unit are overlapped and joined, an anode shared lead, and a second anode junction portion in which the first anode junction portion and the anode shared lead are overlapped and joined. Effect of the Invention

[0008] According to the present disclosure, it is possible to reduce the equivalent series resistance (ESR) of an electrolytic capacitor including a multilayer element. The novel features of the present invention are set forth in the appended claims, but the present invention, both in terms of structure and content, together with other objects and features of the present application, will be better understood from the following detailed description taken in conjunction with the drawings. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view conceptually showing the configuration of a capacitor element according to one embodiment. [Diagram 2] FIG. 1 is a cross-sectional view conceptually showing the configuration of a multilayer element according to an embodiment. [Diagram 3] FIG. 3 is a plan view of the laminated element of FIG. 2. [Figure 4] 4 is a plan view of a laminated element according to a modified example of FIG. 3. FIG. [Diagram 5] 5 is a plan view of an electrolytic capacitor having the multilayer element of FIG. 4. [Figure 6] FIG. 4 is a conceptual diagram of a main part of a laminated element according to another embodiment. [Figure 7] FIG. 13 is a conceptual diagram of a main part of a laminated element according to yet another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In the following, the embodiment of the present disclosure will be described by way of example, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure are obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "numerical value A or more and numerical value B or less." In the following description, when a lower limit and an upper limit of a numerical value related to a specific physical property or condition are exemplified, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined as long as the lower limit is not equal to or greater than the upper limit. When multiple materials are exemplified, one of them may be selected and used alone, or two or more of them may be used in combination.

[0011] The present disclosure also encompasses any combination of features recited in any two or more claims arbitrarily selected from the multiple claims recited in the accompanying claims, i.e., any combination of features recited in any two or more claims arbitrarily selected from the multiple claims recited in the accompanying claims may be used unless a technical contradiction arises.

[0012] The term "electrolytic capacitor" may be read as a "solid electrolytic capacitor" or a "solid-liquid hybrid electrolytic capacitor", and the term "capacitor" may be read as a "capacitor". The solid electrolytic capacitor includes a solid electrolyte. At least a portion of the solid electrolyte may be formed of a conductive polymer.

[0013] An electrolytic capacitor according to an embodiment of the present disclosure (hereinafter also referred to as "electrolytic capacitor (HV)") includes a laminated element. The laminated element is, for example, a structure in which a plurality of plate-shaped capacitor elements are stacked and integrated. The number of capacitor elements included in the laminated element is, for example, 4 or more, and may be 6 or more.

[0014] The laminated element includes a plurality of units connected in parallel. Each of the plurality of units includes a plurality of capacitor elements connected in parallel. Each unit is, for example, a structure in which two or more plate-shaped capacitor elements are stacked and integrated. When the number of capacitor elements constituting each unit is the same, the number of capacitor elements constituting the laminated element is equal to the product (n×m) of the number of units constituting the laminated element (n) and the number of capacitor elements constituting each unit (m). The number of capacitor elements (n×m) included in the laminated element is, for example, 4 or more, and may be 6 or more.

[0015] Each of the plurality of capacitor elements (hereinafter simply referred to as "capacitor element") includes a sheet-shaped (or foil-shaped) anode body having an anode lead portion and an anode main portion, a dielectric layer formed on the surface of the anode main portion, and a solid electrolyte covering at least a portion of the dielectric layer. The solid electrolyte includes, for example, a conductive polymer.

[0016] The material of the anode body may be, for example, a valve metal or an alloy containing a valve metal. The anode body may be formed from a metal foil containing a valve metal. The valve metal may be aluminum, tantalum, niobium, or the like.

[0017] The dielectric layer may be formed, for example, by immersing a metal foil in a chemical conversion solution such as an ammonium adipate solution and subjecting the metal foil to a chemical conversion treatment while applying a voltage as necessary.

[0018] The solid electrolyte includes, for example, a manganese compound and a conductive polymer. As the conductive polymer, for example, polypyrrole, polythiophene, polyaniline, and derivatives thereof can be used. The solid electrolyte including the conductive polymer can be formed, for example, by chemical polymerization and / or electrolytic polymerization of a raw material monomer on a dielectric layer. The solid electrolyte can also be formed, for example, by attaching a solution in which the conductive polymer is dissolved or a dispersion liquid in which the conductive polymer is dispersed to the dielectric layer.

[0019] Each of the multiple units has a first anode bonded portion in which anode lead portions of multiple capacitor elements constituting the unit are stacked and bonded. The anode lead portion, which is a part of the sheet-like anode body, is similarly sheet-like. The multiple sheet-like anode lead portions are stacked to form a laminated structure of the anode lead portions, and the laminated structure is integrated by a technique such as resistance welding, laser welding, ultrasonic welding, friction stir welding, or other welding method, or by crimping, to form the first anode bonded portion. The laminated structure of the anode lead portion or the first anode bonded portion may have a flat shape.

[0020] In the first anode bonding section, it is preferable that the anode lead sections of three or more anode bodies are stacked and bonded. In this case, the bonding process can be simplified and the number of anode common leads does not increase excessively. As a result, it is more advantageous for reducing ESR.

[0021] Each of the multiple units further includes an anode shared lead derived from the first anode junction. That is, each of the multiple units has a second anode junction in which the first anode junction and the anode shared lead are overlapped and joined. The laminated element may have only one anode shared lead, may have the same number of anode shared leads as the number of units (n), or may have a number of anode shared leads different from the number of units (n). That is, each of the multiple units may have an anode shared lead individually, and in that case, the laminated element may have a third anode junction in which the anode shared leads of the multiple units are overlapped and joined. The anode shared lead may be in a sheet shape. And, when there are multiple anode shared leads, they are overlapped to form a laminated structure of the anode shared leads, and the laminated structure may be integrated by a method such as resistance welding, laser welding, ultrasonic welding, friction stir welding, or crimping, to form the third anode junction.

[0022] In the third anode bonding portion, it is preferable that two or more anode shared leads are stacked and bonded. That is, the number of units (n) is preferably 2 or more, and more preferably 3 or more. By forming a sufficient number of units and housing them in a case, the volumetric efficiency of the electrolytic capacitor is improved and it is further advantageous in reducing the ESR.

[0023] As described above, the multiple anode shared leads may be integrated into one by the third anode bonding portion. Also, when the number of units (n) is large, two or more third anode bonding portions may be formed.

[0024] The above configuration provides a multilayer element having anode bodies connected in parallel by a common anode lead, and each of the multiple units is connected in parallel. In this way, all of the capacitor elements constituting the multilayer element are divided into multiple units and a conductive path is formed at the first anode junction and the second anode junction, thereby significantly reducing the ESR per capacitance. The ESR decreases as the number of units (n) constituting the multilayer element increases. For example, the ESR (ESR-n) when multiple units are connected in parallel can be reduced to about 0.1 times the ESR (ESR-1) of one unit alone. In addition, when n units are accommodated in one electrolytic capacitor, it is possible to save space and reduce dead space compared to the case where n electrolytic capacitors are used. Although the mechanism by which the ESR per capacitance is significantly reduced has not been elucidated, it is speculated that the improvement in the degree of freedom of electronic conduction and the expansion of the conductive path contribute to this.

[0025] It is preferable that the third anodic bonding portion protrudes from the first anodic bonding portion so as not to overlap with the first anodic bonding portion. By preventing the third anodic bonding portion and the first anodic bonding portion from overlapping, an increase in the resistance of both bonding portions is suppressed, which is more advantageous for reducing ESR. Furthermore, when the third anodic bonding portion is formed at a position where it does not overlap with the first anodic bonding portion, a third anodic bonding portion with a large bonding area can be easily formed.

[0026] The shared anode lead may be led out of the case of the electrolytic capacitor. When there are multiple shared anode leads, they may be led out of the case of the electrolytic capacitor in a state where they are integrated by a third anode bond portion. When the third anode bond portion is formed at an end of the shared anode lead, the third anode bond portion may be led out.

[0027] The anode shared lead may be connected to an external terminal of the case of the electrolytic capacitor. When there are multiple anode shared leads, they may be connected to the external terminal of the case of the electrolytic capacitor inside the case while being integrated by the third anode bonding part. The external terminal may be the case itself, or may be a member separate from the case. The terminal of the separate member forms a conductive path connecting the inside and outside of the case while being insulated from the case. When the third anode bonding part is formed at the end of the anode body, the third anode bonding part may be connected to the external terminal.

[0028] Each of the first anodic bonding portions of the multiple units may be arranged so as not to overlap at least a portion of the other first anodic bonding portions. In this case, the multiple first anodic bonding portions included in the laminated element are laminated in the lamination direction of the multiple units so that each of the first anodic bonding portions does not overlap at least a portion of the other first anodic bonding portions. The multiple first anodic bonding portions may be laminated in the lamination direction of the multiple units so that each of the first anodic bonding portions does not completely overlap the other first anodic bonding portions.

[0029] The anode shared lead may be, for example, in the form of a tab, and may be formed from a metal foil containing, for example, a transition metal such as iron, copper, nickel, or tin.

[0030] The portion of the third anode bonding portion that protrudes from the first anode bonding portion (hereinafter also referred to as the "anode lead protrusion") protrudes from the outer periphery of the sheet-shaped anode body. The outer shape of the sheet-shaped anode body is usually rectangular. The anode lead protrusion protrudes from either the short side or the long side of the anode body. In particular, when the anode body has a size of 20 mm x 20 mm or less, it is desirable to have the anode lead protrusion protrude from the long side of the anode body in order to improve the volumetric efficiency of the electrolytic capacitor.

[0031] The first anode bonding portion, the second anode bonding portion, and the third anode bonding portion are preferably formed by welding. By welding, a bonding portion having high strength and a sufficiently large bonding area can be formed. The welding method is not particularly limited, but for example, resistance welding, laser welding, and ultrasonic welding are preferable. The laminated structure of the anode lead portion and the laminated structure of the anode shared lead can both have a flat shape. Therefore, a method of sandwiching the object between a pair of electrodes and welding in the bonding process is preferable. For example, the first to third anode bonding portions having a larger bonding area can be formed by ultrasonic welding.

[0032] The second anode bonding portion (or the first anode bonding portion and the second anode bonding portion) may be formed by crimping a plurality of anode lead portions or a first anode bonding portion and an anode shared lead by plastic deformation. For example, the second anode bonding portion (or the first anode bonding portion and the second anode bonding portion) may be formed by stacking a plurality of anode lead portions (or the first anode bonding portion) and an anode shared lead, and crimping a burr formed by drilling a hole from one of the plurality of anode lead portions (or the first anode bonding portion) and the anode shared lead to the other. Such a crimping structure is particularly suitable for stacking a plurality of units such that each of the plurality of first anode bonding portions does not completely overlap with the other first anode bonding portions in the stacking direction. This is because the number of the plurality of anode lead portions included in one unit is not excessively large, and therefore a plurality of crimping structures with good connection can be formed. In this case, each of the multiple stacked anode lead portions or first anode junctions is crimped to different positions of one anode shared lead, resulting in the formation of multiple second anode junctions in which the first anode junctions and the anode shared lead are stacked and joined.

[0033] Each of the capacitor elements may include a sheet-shaped (or foil-shaped) cathode body having a cathode lead portion and a cathode main portion. The cathode body is preferably in contact with a solid electrolyte. By contacting the cathode body with the solid electrolyte, the ESR can be further significantly reduced.

[0034] The cathode body may be formed from a metal foil containing a valve metal. The surface of the metal foil may be roughened. The cathode body may be subjected to a chemical conversion treatment as necessary. A carbon layer, a metal layer (titanium, nickel, etc.), or a metal oxide layer (aluminum oxide, titanium oxide, etc.) may be formed on the surface of the cathode body.

[0035] The capacitor element may further include a separator interposed between the anode body and the cathode body. The separator may be a nonwoven fabric. The nonwoven fabric may be made of fibers such as cellulose, polyethylene terephthalate, vinylon, polyamide (aliphatic polyamide, aromatic polyamide, etc.). The separator may be impregnated with a solid electrolyte.

[0036] The capacitor element may not include a cathode body, but may include a cathode portion. The cathode portion is formed so as to cover at least a portion of the dielectric layer formed on the anode portion of the anode body. The solid electrolyte constitutes the cathode portion. The cathode portion may further include a carbon layer covering the solid electrolyte, a conductive metal layer covering the carbon layer, etc.

[0037] When each of the multiple units has a cathode body, the configuration of the anode body described above may be similarly applied to the cathode body. The description of the anode described above can be applied to all of the present embodiments according to the present disclosure by replacing "anode" with "cathode" unless a contradiction occurs.

[0038] When each of the multiple units has a cathode body, each unit may have a first cathode joint in which the cathode lead portions of the multiple capacitor elements constituting the unit are stacked and joined. The cathode lead portion, which is a part of the sheet-like cathode body, is similarly sheet-like. The multiple sheet-like cathode lead portions are stacked to form a stacked structure of the cathode lead portions, and the stacked structure is integrated by a technique such as resistance welding, laser welding, ultrasonic welding, friction stir welding, or the like, or by crimping, to form the first cathode joint. The stacked structure of the cathode lead portion or the first cathode joint may have a flat shape.

[0039] Each of the multiple units may further include a cathode shared lead derived from the first cathode joint. That is, each of the multiple units has a second cathode joint in which the first cathode joint and the cathode shared lead are overlapped and joined. The laminated element may have only one cathode shared lead, may have the same number of cathode shared leads as the number of units (n), or may have a number of cathode shared leads different from the number of units (n). That is, each of the multiple units may have an individual cathode shared lead, and in that case, the laminated element may have a third cathode joint in which the cathode shared leads of the multiple units are overlapped and joined. The cathode shared lead may be in a sheet shape. And, when there are multiple cathode shared leads, they are overlapped to form a laminated structure of the cathode shared leads, and the laminated structure may be integrated by a method such as resistance welding, laser welding, ultrasonic welding, friction stir welding, or crimping, to form the third cathode joint.

[0040] In the third cathode joint, it is preferable that two or more cathode shared leads are stacked and joined. That is, the number of units (n) is preferably 2 or more, and more preferably 3 or more. By forming a sufficient number of units and housing them in a case, the volumetric efficiency of the electrolytic capacitor is improved and it is further advantageous in reducing the ESR.

[0041] As described above, the multiple cathode shared leads may be integrated into one by the third cathode joint portion. Also, when the number of units (n) is large, two or more third cathode joint portions may be formed.

[0042] With the above configuration, a laminated element is obtained in which the units are connected in parallel by a common cathode lead, and each unit has a plurality of cathode bodies connected in parallel.

[0043] The third cathode bonding portion preferably protrudes from the first cathode bonding portion so as not to overlap with the first cathode bonding portion. The protruding direction of the third cathode bonding portion may be the same as the protruding direction of the third anode bonding portion, or may be the opposite direction. By preventing the third cathode bonding portion and the first cathode bonding portion from overlapping, an increase in the resistance of both bonding portions is suppressed, which is more advantageous for reducing ESR. In addition, when the third cathode bonding portion is formed at a position where it does not overlap with the first cathode bonding portion, a third cathode bonding portion with a large bonding area can be easily formed.

[0044] The cathode shared lead may be led out of the case of the electrolytic capacitor. When there are a plurality of cathode shared leads, they may be led out of the case of the electrolytic capacitor in a state where they are integrated by a third cathode joint. When the third cathode joint is formed at an end of the cathode shared lead, the third cathode joint may be led out.

[0045] The shared cathode lead may be, for example, a tab and may be formed from a metal foil including, for example, a transition metal such as iron, copper, nickel, or tin.

[0046] The cathode shared lead may be connected to an external terminal of the electrolytic capacitor case. When there are multiple cathode shared leads, they may be connected to the external terminal of the electrolytic capacitor case inside the case while being integrated by a third cathode joint. The external terminal may be the case itself or may be a separate member from the case.

[0047] Each of the first cathode bonding portions of the multiple units may be arranged so as not to overlap at least a portion of the other first cathode bonding portions. In this case, the multiple first cathode bonding portions included in the stacked element are stacked in the stacking direction of the multiple units so that each of the first cathode bonding portions does not overlap at least a portion of the other first cathode bonding portions. The multiple first cathode bonding portions may be stacked in the stacking direction of the multiple units so that each of the first cathode bonding portions does not completely overlap the other first cathode bonding portions.

[0048] The portion of the third cathode bonding portion protruding from the first cathode bonding portion (hereinafter also referred to as the "cathode lead protruding portion") protrudes from the outer periphery of the sheet-shaped cathode body. The outer shape of the sheet-shaped cathode body is usually rectangular. The cathode lead protruding portion protrudes from either the short side or the long side of the cathode body. In particular, it is desirable for the cathode lead protruding portion to protrude from the long side of the cathode body on the same side as the anode lead protruding portion in terms of improving the volumetric efficiency of the electrolytic capacitor.

[0049] In the first cathode joint portion, it is preferable that the cathode lead portions of three or more cathode bodies are overlapped and joined, and in the third cathode joint portion, it is preferable that two or more cathode shared leads are overlapped and joined.

[0050] The first cathode bonding portion, the second cathode bonding portion, and the third cathode bonding portion are preferably formed by welding. The welding method is not particularly limited, but for example, resistance welding, laser welding, and ultrasonic welding are preferable. The laminated structure of the cathode lead portion and the laminated structure of the cathode shared lead may both have a flat shape. Therefore, a method of sandwiching the object between a pair of electrodes and welding in the bonding process is preferable. For example, the first to third cathode bonding portions with a larger bonding area can be formed by ultrasonic welding.

[0051] The second cathode bonding portion (or the first cathode bonding portion and the second cathode bonding portion) may be formed by crimping the multiple cathode lead portions or the first cathode bonding portion and the cathode shared lead by plastic deformation. For example, the second cathode bonding portion (or the first cathode bonding portion and the second cathode bonding portion) may be formed by stacking the multiple cathode lead portions (or the first cathode bonding portion) and the cathode shared lead, and crimping a burr formed by drilling a hole from one of the multiple cathode lead portions (or the first cathode bonding portion) and the cathode shared lead to the other. Such a crimping structure is particularly suitable for stacking multiple units so that each of the multiple first cathode bonding portions does not completely overlap with the other first cathode bonding portions in the stacking direction. In this case, each of the multiple stacked cathode lead portions or first cathode joints is crimped to different positions of one cathode shared lead, resulting in the formation of multiple second cathode joints in which the first cathode joints and the cathode shared lead are stacked and joined.

[0052] The capacitor element may further include a liquid component. The liquid component is preferably in contact with the dielectric layer formed on the surface of the anode main part. By bringing the liquid component into contact with the dielectric layer, the repairability of the dielectric layer is improved, and even when a low ESR electrolytic capacitor is used with a large current, the leakage current (LC) can be easily limited to a small value.

[0053] The liquid component may be a non-aqueous solvent, such as ethylene glycol, propylene glycol, sulfolane, γ-butyrolactone, or N-methylacetamide.

[0054] The liquid component may contain an electrolyte salt. By contacting the liquid component containing the electrolyte salt with the dielectric layer, it is possible to further enhance the repairability of the dielectric layer, and by contacting the liquid component containing the electrolyte salt with the solid electrolyte, it is possible to suppress deterioration of the solid electrolyte.

[0055] The electrolyte salt may be an organic salt, such as trimethylamine maleate, triethylamine borodisalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, or mono-1,3-dimethyl-2-ethylimidazolinium phthalate.

[0056] The anode body may have a core and a porous part continuous with the core. The porous part increases the surface area of ​​the anode body, significantly increasing the capacity. In addition, the contact area between the solid electrolyte and the dielectric layer increases, improving the conductivity and further favoring the reduction of ESR. The ratio tc / Tp of the thickness tc of the core to the thickness Tp of the anode body is, for example, 0.5 or less, and may be 0.35 or less. On the other hand, from the viewpoint of ensuring the strength of the anode body, tc / Tp is preferably 0.25 or more.

[0057] The anode body having a core and a porous portion may be formed, for example, by roughening the surface of a metal foil containing a valve metal. The roughening of the metal foil may be performed using an etching treatment technique such as a direct current electrolysis method or an alternating current electrolysis method. Roughening the metal foil refers to forming a large number of projections and recesses on the surface of the metal foil to make it porous. The anode body having a dielectric layer may be produced by roughening the surface of a large-sized metal foil containing a valve metal, subjecting it to a chemical conversion treatment, and then cutting it to a desired size.

[0058] The anode lead may have a region that does not have a porous portion (hereinafter also referred to as a "plain region"). By joining the plain regions of a plurality of anode lead portions together, it is possible to form a first anode bonding portion with lower resistance. In addition, by joining the plain region of the anode lead portion to the anode common lead, it is possible to further reduce the resistance of the bonding portion between the anode lead portion and the anode common lead.

[0059] In electrolytic capacitors containing a solid electrolyte and a liquid component, the anode body is often formed thick. This is because, in order to increase the productivity of electrolytic capacitors and achieve high capacity and high voltage resistance, it is desirable to form the brittle anode body thick so that it can withstand the strong tension during manufacturing. On the other hand, electrolytic capacitors using aluminum foil as the anode body have the advantage that they can easily achieve high capacity and high voltage resistance at low cost. Therefore, by forming the porous part thick, the surface area can be increased, making it possible to achieve both high voltage resistance and high capacity.

[0060] The thickness Tp of the anode body is, for example, 80 μm or more, may be 100 μm or more, or may be 110 μm or more. The larger the thickness Tp of the anode body, the more suitable the electrolytic capacitor is for use with a large current and the easier it is to reduce the ESR. However, from the viewpoint of the capacity and volumetric efficiency of the electrolytic capacitor, there is a limit to the increase in the thickness Tp of the anode body. It is preferable that Tp is 250 μm or less.

[0061] The above-mentioned structure is particularly effective in increasing the withstand voltage of the electrolytic capacitor, for example, to 20 V or more, or even to 25 V or more. When the porous portion is thickened to achieve both high withstand voltage and high capacity, the contact resistance of each joint generally becomes an issue. On the other hand, the above-mentioned structure greatly contributes to reducing the contact resistance.

[0062] An example of an electrolytic capacitor according to the present disclosure will be specifically described below with reference to the drawings. The components described above can be applied to the components of the electrolytic capacitor of the example described below. The components of the electrolytic capacitor of the example described below can be modified based on the above description. The matters described below may also be applied to the above embodiment. Among the components of the electrolytic capacitor of the example described below, components that are not essential to the electrolytic capacitor of the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the shapes and numbers of actual members.

[0063] Fig. 1 is a cross-sectional view conceptually showing a configuration of a capacitor element according to an embodiment. Fig. 2 is a cross-sectional view conceptually showing a configuration of a multilayer element according to an embodiment. Fig. 3 is a plan view of the multilayer element of Fig. 2.

[0064] 1 shows a state in which a plurality of plate-shaped capacitor elements are stacked. Capacitor element 11 includes an anode body 20, a cathode body 30, and a separator 40 interposed therebetween. Anode body 20 and cathode body 30 are made of a valve metal or an alloy containing a valve metal. Separator 40 is made of, for example, a nonwoven fabric. Separator 40 is impregnated with a liquid component or an electrolyte.

[0065] The anode body 20 is in the form of a foil or a sheet, and has a rectangular outer shape. An anode lead portion 21 is provided on one end side in the longitudinal direction of the anode body 20. The remaining part including the other end of the anode body 20 is an anode main portion 22. The surface of the anode main portion 22 is roughened to form a porous portion 22s. That is, the anode main portion 22 has a core portion 22c and a porous portion 22s continuous with the core portion 22c. A dielectric layer is formed on the surface of the porous portion 22s. At least a part of the dielectric layer is covered with a solid electrolyte. On the other hand, the anode lead portion 21 does not have a porous portion. This can reduce the resistance and increase the strength of the first anode junction.

[0066] The ratio tc / Tp of the thickness tc of the core 22c to the thickness Tp of the anode body depends on the type of electrolytic capacitor, but in the case of a hybrid electrolytic capacitor using a solid electrolyte and a liquid component (electrolytic solution), it is, for example, 0.5 or less, and preferably 0.25 to 0.5. The thickness Tp of the anode body is, for example, 80 μm to 250 μm, and preferably 100 μm to 250 μm. In this case, the withstand voltage can be, for example, 20 V or more.

[0067] Cathode body 30 is in a foil or sheet shape and has a rectangular outer shape. Cathode lead portion 31 is provided on one end side in the longitudinal direction of cathode body 30. The remaining portion including the other end of cathode body 30 is cathode main portion 32. Cathode main portion 32 is in contact with the solid electrolyte.

[0068] 2, a plurality of capacitor elements 11 are connected in parallel to form a unit 10. The plurality of units 10 are further connected in parallel to form a multilayer element 1. That is, the multilayer element 1 includes a plurality of units 10 connected in parallel, and each of the plurality of units 10 includes a plurality of capacitor elements 11 connected in parallel.

[0069] Here, three anode bodies 20 and four cathode bodies 30 are stacked with separators between them to form one unit 10. Two units 10 are stacked to form a multilayer element 1. Based on the number of anode bodies 20, one unit 10 is made up of three capacitor elements 11, and the multilayer element 1 is made up of six capacitor elements.

[0070] The anode lead portions 21 of the three capacitor elements 11 constituting each unit 10 are stacked and joined to form a first anode bond portion 210. Since the anode lead portions 21 are sheet-shaped, a strong bond portion with a large bond area can be formed by a method such as resistance welding. The shape of the first anode bond portion 210 is generally flat. The first anode bond portions 210 of the two units 10 are connected to the anode shared leads 211 at second anode bond portions 213, respectively. Since the first anode bond portion 210 and the anode shared lead 211 are sheet-shaped, a strong bond portion 213 with a large bond area can be formed by a method such as resistance welding.

[0071] The cathode lead portions 31 of the three capacitor elements 11 constituting each unit 10 are stacked and joined to form a first cathode joint 310. Since the cathode lead portions 31 are sheet-shaped, a strong joint with a large joint area can be formed by a method such as resistance welding. The shape of the first cathode joint 310 is generally flat. A cathode shared lead 311 is connected to the first cathode joint portions 310 of the two units 10 at a second cathode joint portion 313. Since the first cathode joint portion 310 and the cathode shared lead 311 are sheet-shaped, a strong second cathode joint portion 313 with a large joint area can be formed by a method such as resistance welding.

[0072] The two anode shared leads 211 are overlapped and joined to form a third anode bond portion 212. When the anode shared lead 211 is in a sheet shape, the third anode bond portion 212 has a generally flat shape. In addition, the third anode bond portion 212 protrudes from the first anode bond portion 211 so as not to overlap with the first anode bond portion 211. Therefore, each bond portion can be firmly joined by a technique such as resistance welding.

[0073] The two cathode shared leads 311 are overlapped and joined to form a third cathode joint portion 312. When the cathode shared lead 311 is in a sheet shape, the third cathode joint portion 312 has a generally flat shape. Furthermore, the third cathode joint portion 312 protrudes from the first cathode joint portion 311 so as not to overlap with the first cathode joint portion 311. Therefore, each joint portion can be firmly joined by a technique such as resistance welding.

[0074] Fig. 4 is a plan view of a multilayer element 1A which is a modified example of the multilayer element 1 of Fig. 3. The structure of the multilayer element 1A is similar to that of the multilayer element 1 of Figs. 2 and 3, except that the anode shared lead 211 (third anode bonding portion 212) and the cathode shared lead 311 (third cathode bonding portion 312) protrude from the long side of the anode body 20 (and the cathode body 30). In other words, the anode lead protrusion and the cathode lead protrusion both protrude in the same direction from the long side of the anode body. Such a structure can improve the volumetric efficiency of the electrolytic capacitor.

[0075] 5 is a plan view of an electrolytic capacitor 100 including the multilayer element 1A of FIG. 4. The multilayer element 1A is housed in a case 70, and an anode shared lead 211 and a cathode shared lead 311 are led out from one side of the case 70. The multilayer element 1A may be housed in the case 70 together with a liquid component or an electrolyte. The case 70 may be made of a laminate sheet having a metal barrier layer, but is not particularly limited thereto. For example, the case 70 may be made of a metal such as aluminum, stainless steel, copper, iron, or brass, or an alloy thereof.

[0076] Fig. 6 is a conceptual diagram showing a main part of the anode lead portion 21 side of the multilayer element 1 according to another embodiment. Fig. 6(a) is a plan view (viewed from the Z direction), and Figs. 6(b) and (c) are front views viewed from the X direction. In this embodiment, in the stacking direction of the multiple units 10, the multiple first anode lead portions 21 (first anode bonding portions 210) of each unit 10 are arranged side by side so as not to overlap with the multiple first anode lead portions 21 (first anode bonding portions 210) of the other units 10. The anode shared lead 211 is arranged in the center in the stacking direction.

[0077] 6(b) shows a state before the multiple first anode lead portions 21 (first anode bonding portion 210) of each unit 10 are bonded to the anode shared lead 211, and FIG. 6(c) shows a state after the multiple first anode lead portions 21 (first anode bonding portion 210) of each unit 10 have been bonded to the anode shared lead 211 by welding. The first anode bonding portion 210 and the second anode bonding portion 213 may be formed simultaneously by welding, or the multiple first anode lead portions 21 of each unit 10 may be bonded in advance by welding or the like to form the first anode bonding portion 210, and then the second anode bonding portion 213 may be formed.

[0078] Fig. 7 is a conceptual diagram of a main part of the anode lead portion 21 side of a multilayer element 1 according to yet another embodiment. Fig. 7(a) is a plan view (viewed from the Z direction), and Fig. 7(b) is a front view viewed from the X direction. In this embodiment, in the stacking direction of the multiple units 10, the multiple first anode lead portions 21 (first anode bonding portions 210) of each unit 10 are arranged side by side so as not to overlap with the multiple first anode lead portions 21 (first anode bonding portions 210) of the other units 10. The anode shared lead 211 is arranged in the center in the stacking direction.

[0079] The crimping portion 50 of the second anodic bonding portion is formed by overlapping the overlapping multiple anode lead portions 21 (or the pre-formed first anodic bonding portion 210) and the anode shared lead 211, drilling a hole from one side, and crimping the burr formed to the other side. If the first anodic bonding portion 210 is not formed in advance, the first anodic bonding portion 210 is formed simultaneously with the crimping portion 50 of the second anodic bonding portion. Therefore, the first anodic bonding portion 210 that bonds and integrates the multiple anode lead portions 21 is formed simultaneously with the crimping portion 50.

[0080] [Example] The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0081] Example 1 (Preparation of anode body) An aluminum foil having a thickness of 110 μm was etched to roughen the surface of the aluminum foil. Then, a dielectric layer was formed on the surface of the aluminum foil by chemical conversion treatment. The chemical conversion treatment was performed by immersing the aluminum foil in an ammonium adipate solution and applying a voltage of 36 V to the aluminum foil. The aluminum foil after the chemical conversion treatment was cut into a size of 10 mm x 50 mm to obtain an anode body. However, an area on one end side in the longitudinal direction that was not roughened and was not subjected to chemical conversion treatment was left as an anode lead portion.

[0082] (Preparation of the cathode body) A coating liquid containing particles of a conductive carbon material and a binder resin was applied to the surface of an etched aluminum foil (thickness 30 μm), dried to form a carbon layer (thickness 350 nm), and cut to a length x width of 10 mm x 50 mm to obtain a cathode foil, with an area without a carbon layer remaining on one end in the longitudinal direction as a cathode lead portion.

[0083] (Layered element) Three anode bodies and four cathode bodies were alternately stacked with separators between them to form a unit including three capacitor elements as shown in Figure 2. The anode lead and cathode lead were positioned at one end and the other end of the stacked structure consisting of the anode body, cathode body, and separator.

[0084] Two units were formed. The three anode leads of each unit were stacked and joined by resistance welding to form the first anode joint. The four cathode leads of each unit were stacked and joined by resistance welding to form the first cathode joint.

[0085] Next, one end of the anode common lead was joined to the first anode junction of each unit to form a second anode junction, and one end of the cathode common lead was joined to the first cathode junction of each unit to form a second cathode junction.

[0086] Next, the other ends of the two anode common leads were overlapped and joined by resistance welding to form a third anode junction, and the other ends of the two cathode common leads were overlapped and joined by resistance welding to form a third cathode junction.

[0087] A polymerization liquid containing 3,4-ethylenedioxythiophene as a precursor of the conductive polymer and a solution of ferric paratoluenesulfonate as an oxidizing agent that also serves as a dopant was prepared. The laminated element was immersed in the polymerization liquid, and then the laminated element was heated and thermally polymerized. In this way, a solid electrolyte containing poly(3,4-ethylenedioxythiophene) (conductive polymer) doped with paratoluenesulfonic acid (dopant) was attached to the laminated element.

[0088] Next, the multilayer element was immersed in an electrolyte solution prepared by dissolving triethylamine phthalate in ethylene glycol at a predetermined concentration, and allowed to stand for 5 minutes in a reduced pressure atmosphere (40 kPa) to impregnate the multilayer element with the electrolyte.

[0089] (Sealing of capacitor elements) The capacitor element was placed in an aluminum laminate case together with the electrolyte, and the ends of the anode common lead and cathode common lead were led out of the case, and the opening of the case was sealed to complete the electrolytic capacitor. After that, the capacitor was aged for 2 hours at 135°C while applying the rated voltage.

[0090] [evaluation] The initial characteristics of the electrolytic capacitor were measured: capacitance (μF) and ESR (mΩ). An LCR meter was used to measure the initial capacitance (μF) at a frequency of 120Hz. An LCR meter was also used to measure the ESR (mΩ) of the electrolytic capacitor at a frequency of 100kHz. The results were an ESR of 0.9mΩ and a capacitance of 762μF.

[0091] Comparative Example 1 An electrolytic capacitor was fabricated and evaluated in the same manner as in Example 1, except that the two units were not connected with a common anode lead and a common cathode lead, and one unit was housed alone in a case. As a result, the ESR was 6.3 mΩ, and the capacitance was 381 μF. In other words, the ESR per capacitance was much larger than in Example 1.

[0092] Example 2 Three units were fabricated, connected in parallel with a common anode lead and a common cathode lead, and housed in a case. An electrolytic capacitor was fabricated and evaluated in the same manner as in Example 1. As a result, the ESR was 0.4 mΩ and the capacitance was 1139 μF. In other words, the ESR per capacitance was even smaller than in Example 1.

[0093] Example 3 An electrolytic capacitor was fabricated and evaluated in the same manner as in Example 1, except that seven anode bodies and eight cathode bodies were alternately laminated with separators between them to form a unit including seven capacitor elements. As a result, the ESR was 0.1 mΩ, and the capacitance was 1614 μF. In other words, the ESR per capacitance was even smaller than in Example 1.

[0094] Comparative Example 2 An electrolytic capacitor was fabricated and evaluated in the same manner as in Example 3, except that the two units were not connected with a common anode lead and a common cathode lead, and one unit was housed alone in a case. As a result, the ESR was 3 mΩ, and the capacitance was 806 μF. In other words, the ESR per capacitance was much larger than in Example 3.

[0095] Although the present invention has been described with respect to the presently preferred embodiments, such disclosure should not be interpreted as limiting. Various variations and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. Accordingly, the appended claims should be interpreted to cover all variations and modifications without departing from the true spirit and scope of the present invention.

[0096] (Additional Note) The above description discloses the following techniques. (Technology 1) The laminated element includes: The laminated element includes a plurality of units connected in parallel, Each of the plurality of units includes a plurality of capacitor elements connected in parallel; Each of the plurality of capacitor elements is a sheet-like anode body having an anode lead portion and an anode main portion; a dielectric layer formed on a surface of the anode main portion; a solid electrolyte covering at least a portion of the dielectric layer; Equipped with Each of the plurality of units comprises: a first anode bonding portion in which the anode lead portions of the plurality of capacitor elements constituting the unit are stacked and bonded; A common anode lead; a second anode junction portion in which the first anode junction portion and the anode shared lead are overlapped and joined. (Technology 2) The electrolytic capacitor according to Technical Problem 1, wherein the anode lead portions of three or more of the anode bodies are stacked and joined in the first anode joining portion. (Technology 3) Each of the plurality of units has the anode shared lead; The electrolytic capacitor according to Technology 1 or 2, wherein the laminated element has a third anode junction where the anode shared leads of the multiple units are stacked and joined. (Technology 4) The electrolytic capacitor according to any one of Techniques 1 to 3, wherein the third anodic bonding portion protrudes from the first anodic bonding portion so as not to overlap with the first anodic bonding portion. (Technology 5) The electrolytic capacitor according to technique 3 or 4, wherein two or more of the anode shared leads are overlapped and joined in the third anode junction portion. (Technology 6) The electrolytic capacitor according to any one of Techniques 1 to 5, wherein the first anodic bonding portion of each of the plurality of units is arranged so as not to overlap at least a portion of the other first anodic bonding portions. (Technology 7) 7. The electrolytic capacitor according to any one of techniques 1 to 6, wherein the first anodic bonded portion, the second anodic bonded portion, and the third anodic bonded portion are formed by welding. (Technology 8) The electrolytic capacitor according to any one of techniques 1 to 6, wherein the second anode bonding portion is formed by crimping a plurality of the anode lead portions or the first anode bonding portion and the anode shared lead by plastic deformation. (Technology 9) The electrolytic capacitor according to Technology 8, wherein the second anode bonding portion is formed by stacking a plurality of the anode lead portions or the first anode bonding portions and the anode shared lead, and drilling a burr formed from one of the plurality of the anode lead portions or the first anode bonding portions and the anode shared lead, and crimping the burr to the other. (Technology 10) Each of the plurality of capacitor elements includes a sheet-like cathode body having a cathode lead portion and a cathode main portion, Each of the plurality of units comprises: a first cathode joining portion in which the cathode lead portions of the plurality of capacitor elements constituting the unit are overlapped and joined; A shared cathode lead; The electrolytic capacitor according to any one of techniques 1 to 9, further comprising: a second cathode joint portion in which the first cathode joint portion and the cathode shared lead are overlapped and joined. (Technology 11) 11. The electrolytic capacitor according to any one of claims 1 to 10, wherein the cathode body is in contact with the solid electrolyte. (Technology 12) The electrolytic capacitor according to any one of Techniques 1 to 11, further comprising a liquid component. (Technology 13) 13. The electrolytic capacitor according to claim 12, wherein the liquid component comprises an electrolyte salt. (Technology 14) The anode body has a core portion and a porous portion continuous with the core portion, 14. The electrolytic capacitor according to any one of techniques 1 to 13, wherein a ratio of the thickness tc of the core portion to the thickness Tp of the anode body: tc / Tp is 0.5 or less. (Technology 15) The electrolytic capacitor according to claim 14, wherein the anode lead portion has a region that does not have the porous portion. (Technology 16) 16. The electrolytic capacitor according to claim 14, wherein the thickness Tp of the anode body is 100 μm or more. (Technology 17) 17. The electrolytic capacitor according to any one of Techniques 1 to 16, having a withstand voltage of 20 V or more. [Industrial Applicability]

[0097] The present disclosure can be used for electrolytic capacitors. [Explanation of symbols]

[0098] 100: Electrolytic capacitor 1: Stacked element 10: Unit 11: Capacitor element 20: Anode body 21: Anode drawer 22: Anode main part 22c: core 22s: Porous part 210: 1st anode joint 211: Anode common lead 212:Second anode joint 30: Cathode body 31: Cathode lead-out section 32: Cathode main part 310: 1st cathode junction 311: Cathode common lead 312:Second cathode junction 40: Separator 50: Crimping part 70: Case

Claims

1. The laminated element includes: The laminated element includes a plurality of units connected in parallel, Each of the plurality of units includes a plurality of capacitor elements connected in parallel; Each of the plurality of capacitor elements is a sheet-like anode body having an anode lead portion and an anode main portion; a dielectric layer formed on a surface of the anode main portion; a solid electrolyte covering at least a portion of the dielectric layer; Equipped with Each of the plurality of units comprises: a first anode bonding portion in which the anode lead portions of the plurality of capacitor elements constituting the unit are overlapped and bonded; A common anode lead; a second anode junction portion in which the first anode junction portion and the anode shared lead are overlapped and joined.

2. 2 . The electrolytic capacitor according to claim 1 , wherein the anode lead portions of three or more of the anode bodies are stacked and joined in the first anodic bonding portion.

3. Each of the plurality of units has the anode shared lead; The electrolytic capacitor according to claim 1 , wherein the laminated element has a third anode junction where the anode shared leads of the multiple units are overlapped and joined.

4. The electrolytic capacitor according to claim 1 , wherein the third anodic bonding portion protrudes from the first anodic bonding portion so as not to overlap the first anodic bonding portion.

5. The electrolytic capacitor according to claim 3 , wherein two or more of the anode shared leads are overlapped and joined in the third anodic joining portion.

6. 2 . The electrolytic capacitor according to claim 1 , wherein the first anodic bonding portion of each of the plurality of units is arranged so as not to overlap at least a portion of the other first anodic bonding portions.

7. 2. The electrolytic capacitor according to claim 1, wherein the first anodic bonded portion, the second anodic bonded portion, and the third anodic bonded portion are formed by welding.

8. 2 . The electrolytic capacitor according to claim 1 , wherein the second anode bonding portion is formed by crimping the plurality of anode lead portions or the first anode bonding portion and the anode shared lead by plastic deformation.

9. 9. The electrolytic capacitor according to claim 8, wherein the second anode bonding portion is formed by stacking a plurality of the anode lead portions or the first anode bonding portions and the anode shared lead, and drilling a burr from one of the plurality of the anode lead portions or the first anode bonding portions and the anode shared lead, and crimping the burr to the other.

10. Each of the plurality of capacitor elements includes a sheet-like cathode body having a cathode lead portion and a cathode main portion, Each of the plurality of units comprises: a first cathode joining portion in which the cathode lead portions of the plurality of capacitor elements constituting the unit are overlapped and joined; A shared cathode lead; 2. The electrolytic capacitor according to claim 1, further comprising: a second cathode joint portion in which the first cathode joint portion and the cathode shared lead are overlapped and joined.

11. The electrolytic capacitor of claim 1 , wherein the cathode body is in contact with the solid electrolyte.

12. The electrolytic capacitor of claim 1 further comprising a liquid component.

13. The electrolytic capacitor of claim 12 , wherein the liquid component comprises an electrolyte salt.

14. The anode body has a core portion and a porous portion continuous with the core portion, 2. The electrolytic capacitor according to claim 1, wherein a ratio of a thickness tc of the core portion to a thickness Tp of the anode body: tc / Tp is 0.5 or less.

15. The electrolytic capacitor according to claim 14 , wherein the anode lead portion has a region that does not have the porous portion.

16. 15. The electrolytic capacitor according to claim 14, wherein the anode body has a thickness Tp of 100 μm or more.

17. 2. The electrolytic capacitor according to claim 1, having a withstand voltage of 20 V or more.

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