Electrolytic capacitor and method for manufacturing the same

Abstract

To provide an electrolytic capacitor and a manufacturing method thereof that improve reliability of an electrolytic capacitor in which a first end of an anode lead portion of an anode foil is exposed from an exterior body.SOLUTION: An electrolytic capacitor 11 includes a capacitor element 10, an exterior housing 14 that seals the capacitor element, and external electrodes 15, 16. The capacitor element includes an anode foil 3 having an anode lead portion 1 including a first end 1a and a cathode forming portion 2 including a second end 2a, a dielectric layer formed on the surface of the cathode forming portion, and a cathode portion 6 that covers at least a portion of the dielectric layer. The first end of the anode lead portion protrudes from an end face of the exterior body, and at least a portion of the first end is in contact with the external electrode.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electrolytic capacitor and a method for manufacturing the same.

Background Art

[0002] An electrolytic capacitor includes a capacitor element, an exterior body that seals the capacitor element, and an external electrode electrically connected to the anode side of the capacitor element. The capacitor element includes an anode foil having an anode lead-out portion including a first end portion and a cathode forming portion including a second end portion, a dielectric layer formed on the surface of the cathode forming portion, and a cathode portion covering at least a part of the dielectric layer. As a method of electrically connecting the anode lead-out portion and the external electrode, there is a method of electrically connecting the first end portion exposed from the exterior body to the external electrode.

[0003] Patent Document 1 describes an electrolytic capacitor in which the surface of the anode and / or the lead is processed into an uneven shape to increase the surface area connected to the anode terminal and reduce the connection resistance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, the surface of the anode foil (anode lead-out portion and cathode forming portion) is roughened by etching, and the anode lead-out portion and the cathode forming portion each have a core portion and a porous body (porous portion) formed on the surface of the core portion. When connecting the anode lead-out portion to the external electrode, each of the core portion and the porous portion of the anode lead-out portion is joined to the external electrode.

[0006] However, since the bonding strength between the porous portion and the external electrode is lower than the bonding strength between the core portion and the external electrode, it is difficult to increase the bonding strength between the anode lead-out portion and the external electrode. Further, due to the low adhesion between the porous portion and the external electrode, air (oxygen and moisture) can enter the inside of the electrolytic capacitor through the interface between the porous portion and the external electrode. As a result, for example, the air that has entered the inside of the electrolytic capacitor may come into contact with the cathode portion, causing the solid electrolyte layer contained in the cathode portion to deteriorate and the ESR to increase.

Means for Solving the Problems

[0007] One aspect of the present invention relates to an electrolytic capacitor having an anode foil having an anode lead-out portion including a first end portion and a cathode forming portion including a second end portion, a dielectric layer formed on the surface of the cathode forming portion, and a cathode portion covering at least a part of the dielectric layer. The electrolytic capacitor further includes an exterior body for sealing the capacitor element and an external electrode. The first end portion of the anode lead-out portion protrudes from the end face of the exterior body, and at least a part of the first end portion is in contact with the external electrode.

[0008] Another aspect of the present invention relates to a method for manufacturing an electrolytic capacitor, the method including: a first step of forming a capacitor element having an anode foil having an anode lead-out portion and a cathode forming portion, a dielectric layer formed on the cathode forming portion, and a cathode portion covering at least a part of the dielectric layer; a second step of covering the capacitor element with an exterior body; a third step of cutting the exterior body together with the anode lead-out portion to form a first end portion having an end face exposed from the cut surface of the exterior body on the anode lead-out portion; a fourth step of removing a part of the exterior body exposed at the cut surface of the exterior body to project the first end portion from the end face of the exterior body; and a fifth step of bonding the projected first end portion to an external electrode.

Advantages of the Invention

[0009] According to the present invention, the reliability of an electrolytic capacitor in which the first end portion of the anode lead-out portion of the anode foil is exposed from the exterior body can be improved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0011] The electrolytic capacitor according to an embodiment of the present invention includes a capacitor element, an exterior body that seals the capacitor element, and an external electrode. The capacitor element has an anode foil having an anode lead-out portion including a first end portion and a cathode forming portion including a second end portion, a dielectric layer formed on the surface of the cathode forming portion, and a cathode portion covering at least a part of the dielectric layer. And the first end portion of the anode lead-out portion protrudes from the end face of the exterior body, and at least a part of the first end portion is in contact with the external electrode.

[0012] Since the anode lead-out portion protrudes from the end face of the exterior body, the electrolytic capacitor has improved joinability between the anode lead-out portion and the external electrode. Since the adhesion between the anode lead-out portion and the external electrode is high, the reliability of the connection between the external electrode and the anode lead-out portion can be improved. Also, peeling of the external electrode from the exterior body is suppressed.

[0013] Preferably, at least a part of the roughened portion is missing at the first end of the anode lead-out portion. The surfaces of the anode lead-out portion and the cathode forming portion of the capacitor element may be roughened respectively, and a porous body (porous portion) may also be formed around the first end of the surface of the anode lead-out portion. Even in this case, since the porous portion does not intervene in the joint portion between the anode lead-out portion and the external electrode, the joint property can be improved. In order to make the roughened portion missing, for example, after covering the capacitor element with an outer package, cutting the outer package to expose the first end of the anode lead-out portion from the outer package, the roughened portion exposed by the blasting process described later can be removed.

[0014] From the viewpoint of obtaining a strong joint between the anode lead-out portion and the external electrode, the protruding length of the first end protruding from the end face of the outer package is preferably 0.2 mm or more. On the other hand, the longer the protruding length of the first end, the more difficult it is to form the outer surface of the external electrode flat. The protruding length of the first end is such that the first end does not protrude from the outer surface of the external electrode, in other words, it is preferably shorter than the total thickness of the external electrode (corresponding to H in FIG. 2 described later). X to be equivalent).

[0015] (Anode foil) The anode foil can include valve action metals, alloys containing valve action metals, and intermetallic compounds containing valve action metals, etc. These materials can be used alone or in combination of two or more. As the valve action metal, aluminum, tantalum, niobium, titanium, etc. can be used.

[0016] The surface of the anode foil including at least the cathode forming portion is roughened by, for example, etching, and a porous portion is formed on the surface of the cathode forming portion. After arranging a predetermined masking member on the surface of the anode lead-out portion, it is also possible to perform an etching process. On the other hand, the entire surface of the anode foil is etched It is also possible to perform the processing of forming the porous portion. In the latter case, the porous portion is also formed on the surface of the anode lead-out portion. As the etching process, a known method may be used, for example, electrolytic etching. The masking member is not particularly limited and may be an insulator such as resin or a conductor containing a conductive material.

[0017] (Dielectric layer) The dielectric layer is formed, for example, by anodizing the valve action metal on the surface of the cathode forming portion by a chemical conversion treatment or the like. The dielectric layer contains an oxide of the valve action metal. For example, when aluminum is used as the valve action metal, the dielectric layer contains aluminum oxide. The dielectric layer is formed along the surface of the cathode forming portion being etched (including the inner wall surface of the pores of the porous portion). Note that the method of forming the dielectric layer is not limited to this, and it is sufficient if an insulating layer that functions as a dielectric can be formed on the surface of the cathode forming portion. The dielectric layer may be formed on the porous portion on the surface of the anode lead-out portion.

[0018] The cathode portion includes a solid electrolyte layer that covers at least a part of the dielectric layer, and a cathode lead-out layer that covers at least a part of the solid electrolyte layer. Hereinafter, the solid electrolyte layer and the cathode lead-out layer will be described.

[0019] (Solid electrolyte layer) The solid electrolyte layer contains, for example, a conductive polymer. As the conductive polymer, for example, polypyrrole, polythiophene, polyaniline, and their derivatives can be used. 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, it can be formed by applying a solution in which a conductive polymer is dissolved or a dispersion in which a conductive polymer is dispersed to the dielectric layer. The solid electrolyte layer may contain a manganese compound.

[0020] (Cathode lead-out layer) The cathode lead-out layer includes a carbon layer and a silver paste layer. The carbon layer only needs to have conductivity, and for example, it can be formed using a conductive carbon material such as graphite. The carbon layer is formed, for example, by applying a carbon paste to at least a part of the surface of the solid electrolyte layer. For the silver paste layer, for example, a composition containing silver powder and a binder resin (such as an epoxy resin) can be used. The silver paste layer is formed, for example, by applying a silver paste to the surface of the carbon layer. Note that the configuration of the cathode lead-out layer is not limited to this, and any configuration having a current collection function is acceptable.

[0021] (Outer package) The outer package preferably contains a cured product of a curable resin composition and may also contain a thermoplastic resin or a composition containing the same.

[0022] The outer package can be formed using molding techniques such as injection molding, insert molding, and compression molding. For example, the outer package can be formed by filling a curable resin composition or a thermoplastic resin (composition) into a predetermined location so as to cover the capacitor element using a predetermined mold.

[0023] The curable resin composition may contain, in addition to the curable resin, a filler, a curing agent, a polymerization initiator, and / or a catalyst, etc. Examples of the curable resin include a photocurable resin and a thermosetting resin. The curing agent, polymerization initiator, catalyst, etc. are appropriately selected according to the type of the curable resin.

[0024] As a method for exposing the first end portion of the anode lead-out portion from the outer package, for example, after covering the capacitor element with the outer package, the surface of the outer package is polished so that the first end portion is exposed from the outer package or a method of separating a part of the outer package can be mentioned. As a method for cutting the outer package, dicing is preferable. As a result, the exposed end surface of the first end portion of the anode lead-out portion appears on the cut surface. Then, further, a part of the exposed outer package can be removed by blasting or the like to project the first end portion of the anode lead-out portion from the outer package.

[0025] (External electrode) The external electrode preferably includes a first electrode layer covering at least a part of the first end portion and at least a part of the exterior body, and a second electrode layer formed on the surface of the first electrode layer. By covering a part of the surface of the exterior body together with the surface of the first end portion exposed from the exterior body with the first electrode layer, formation of the natural oxide film on the first end portion is suppressed. From the viewpoint of suppressing the formation of the natural oxide film on the first end portion, it is preferable that the exterior body is covered with the first electrode layer so as to surround the periphery of the exposed surface of the first end portion from the exterior body.

[0026] The first electrode layer is preferably a metal layer. The metal layer is, for example, a plating layer. The metal layer contains, for example, at least one selected from the group consisting of nickel, copper, zinc, tin, silver, and gold. For the formation of the first electrode layer, for example, film-forming techniques such as an electrolytic plating method, an electroless plating method, a sputtering method, a vacuum evaporation method, a chemical vapor deposition (CVD) method, a cold spray method, and thermal spraying may be used. The first electrode layer that adheres to the first end portion and a part of the exterior body can be easily formed by the above method.

[0027] The first electrode layer is covered with the second electrode layer. Thereby, oxidation degradation of the first electrode layer is suppressed. For the second electrode layer, the materials and formation methods exemplified for the first electrode layer can be used. From the viewpoint of adhesion to the first electrode layer, the second electrode layer is preferably a conductive resin layer. The conductive resin layer contains, for example, a resin and a conductive material dispersed in the resin. The resin contains, for example, a cured product of a curable resin composition or a thermoplastic resin (composition). The conductive material contains, for example, at least one selected from the group consisting of silver, copper, and carbon.

[0028] The protruding length H1 of the first end portion protruding from the end face of the exterior body is preferably longer than the thickness H2 of the first electrode layer (see FIG. 2). Since the outer surface of the first electrode layer covered with the second electrode layer has irregularities, the adhesion between the first electrode layer and the second electrode layer can be improved.

[0029] Hereinafter, an example of the electrolytic capacitor according to the present invention will be described with reference to FIG. 1. FIG. 1 is a cross-sectional view schematically showing the structure of the electrolytic capacitor according to an embodiment of the present invention. Note that the electrolytic capacitor according to the present invention is not limited thereto.

[0030] As shown in FIG. 1, the electrolytic capacitor 11 includes a plurality of capacitor elements 10. The capacitor element 10 includes an anode foil 3 having an anode lead-out portion 1 including a first end portion 1a and a cathode forming portion 2 including a second end portion 2a. The cathode forming portion 2 has a core portion 4 and a porous portion 5 formed on the surface of the core portion 4 by etching.

[0031] The capacitor element 10 includes a dielectric layer (not shown) formed on the surface of the cathode forming portion 2 of the anode foil 3. The dielectric layer is formed along the surface of the porous portion 5. At least a part of the dielectric layer covers the inner wall surface of the pores of the porous portion 5 and is formed along the inner wall surface. In FIG. 1, a porous portion 5 is also formed on the surface of the anode lead-out portion 1 of the anode foil 3 by etching, and a dielectric layer is formed along the surface of the porous portion 5.

[0032] The capacitor element 10 includes a cathode portion 6 that covers at least a part of the dielectric layer. The cathode portion 6 includes a solid electrolyte layer 7 that covers at least a part of the dielectric layer and a cathode lead-out layer that covers at least a part of the solid electrolyte layer 7. The cathode lead-out layer includes a carbon layer 8 that covers at least a part of the solid electrolyte layer 7 and a silver paste layer 9 that covers the carbon layer 8. The surface of the dielectric layer has an uneven shape corresponding to the shape of the surface of the porous portion 5. The solid electrolyte layer 7 is preferably formed so as to fill the unevenness of the dielectric layer. In FIG. 1, the portion of the anode foil 3 on which the cathode portion 6 is formed via the dielectric layer on the anode foil 3 is the cathode forming portion 2, and the portion of the anode foil 3 where the cathode portion 6 is not formed is the anode lead-out portion 1. An uneven shape corresponding to the shape of the surface of the porous portion 5 is formed. The solid electrolyte layer 7 is preferably formed so as to fill the unevenness of the dielectric layer. In FIG. 1, the portion of the anode foil 3 on which the cathode portion 6 is formed via the dielectric layer on the anode foil 3 is the cathode forming portion 2, and the portion of the anode foil 3 where the cathode portion 6 is not formed is the anode lead-out portion 1.

[0033] Of the regions of the anode foil 3 that do not face the cathode portion 6, an insulating separation layer 12 is formed on the portion adjacent to the cathode portion 6 so as to cover the surface of the anode foil 3, and contact between the cathode portion 6 and the anode lead portion 1 is restricted. The separation layer 12 is, for example, an insulating resin layer.

[0034] A plurality of capacitor elements 10 are stacked such that a plurality of anode foils 3 overlap each other in the same direction. An anode stacked portion where the anode lead portions 1 are stacked and a cathode stacked portion where the cathode portions 6 are stacked are formed. In the plurality of capacitor elements 10, the cathode portions 6 adjacent to each other in the stacking direction are electrically connected via a conductive adhesive layer 13. For the formation of the adhesive layer 13, for example, a conductive adhesive is used. The adhesive layer 13 contains, for example, silver.

[0035] The electrolytic capacitor 11 includes an exterior body 14 that seals a plurality of capacitor elements 10 and exposes a plurality of first end portions 1a. The exterior body 14 has a substantially rectangular parallelepiped outer shape, and the electrolytic capacitor 11 also has a substantially rectangular parallelepiped outer shape. The exterior body 14 has a first side surface 14a that is one end surface and a second side surface 14b that is an end surface on the side opposite to the first side surface 14a. The plurality of first end portions 1a are each exposed from the first side surface 14a of the exterior body 14.

[0036] The electrolytic capacitor 11 includes an anode-side external electrode 15 that is electrically connected to the plurality of first end portions 1a exposed from the exterior body 14. In order to electrically connect each of the plurality of first end portions 1a exposed from the exterior body 14 to the anode-side external electrode 15, it is not necessary to bundle the plurality of anode lead portions 1, and it is not necessary to secure a length for bundling the plurality of anode lead portions 1. Therefore, compared with the case of bundling the plurality of anode lead portions 1, the ratio of the anode lead portions 1 in the anode foil can be reduced to increase the capacitance.

[0037] The external electrode 15 on the anode side has a first electrode layer 15a on the anode side that covers the first side surface 14a of the exterior body 14 together with the end faces of a plurality of first end portions 1a exposed from the exterior body 14, and a second electrode layer 15b on the anode side formed on the surface of the first electrode layer 15a on the anode side. As the external electrode 15 on the anode side, those exemplified as the external electrode above can be used.

[0038] The first side surface 14a of the exterior body 14 is formed in a concave shape as a result of a part of the exterior body 14 being removed. As a result, the first end portion 1a of the anode lead-out portion 1 protrudes from the exterior body. Further, in the vicinity of the first end portion 1a, the porous portion 5 is removed, and the core portion is exposed on the upper surface 1c of the anode lead-out portion 1 in the vicinity of the end portion 1a (see FIG. 2). The exposed core portion and the first end portion 1a are in direct contact with the external electrode 15 (first electrode layer 15a) on the anode side. Due to the unevenness of the first side surface 14a and the end face of the first end portion 1a, the first electrode layer 15a on the anode side is also formed with unevenness on the surface, but the second electrode layer 15b on the anode side covering the first electrode layer 15a on the anode side is formed such that its outer surface is flat.

[0039] FIG. 2 is an enlarged view of the periphery of the first end portion 1a in FIG. 1. The first end portion 1a protrudes toward the outer surface of the second electrode layer 15b in a direction perpendicular to the outer surface of the second electrode layer 15b. Conversely, the first side surface 14a is formed in a concave shape having a depression. Taking the outer surface of the second electrode layer 15b formed in a planar shape as a reference plane. At the first side surface 14a between adjacent anode lead-out portions 1, let the position where the distance from the reference plane is the farthest (that is, the deepest position of the depression) be X. Let the position where the distance from the reference plane is the closest among the end faces of the first end portion 1a be Y. Let the distance from the reference plane at position X be H X and the distance from the reference plane at position Y be H Y be. When paying attention to the first end portion 1a of a certain anode lead-out portion 1, the protrusion length H1 of the first end portion 1a protruding from the first side surface 1 4a of the exterior body 14 is H1 = min{H X}-H Y It is defined as follows. When there are a plurality of anode lead-out portions 1, there are a plurality of recesses in the first side surface 14a, and there may be a plurality of positions X. However, the one with the closest distance from the reference plane is adopted.

[0040] The protruding length H1 is preferably 0.2 mm or more. A strong bond can be obtained between the anode lead-out portion and the external electrode.

[0041] Also, the protruding length H1 is preferably longer than the thickness of the first electrode layer 15a. Note that the thickness of the first electrode layer 15a is the thickness H2 of the first electrode layer 15a at the position X of the depression on the first side surface 14a. Therefore, the protruding length H1 being longer than the thickness H2 of the first electrode layer 15a (H1 > H2) means that even after the formation of the first electrode layer 15a, the outer surface of the first electrode layer 15a (that is, the surface covered by the second electrode layer 15b) has irregularities. The formation of the first electrode layer 15a in an uneven shape can improve the adhesion with the second electrode layer 15b.

[0042] The electrolytic capacitor 11 includes a cathode-side external electrode 16 electrically connected to the cathode portion 6. More specifically, the exterior body 14 exposes the end portion 6a on the second end portion 2a side of the plurality of cathode portions 6 and the end portion 13a on the second end portion 2a side of the plurality of adhesive layers 13, respectively. The cathode-side external electrode 16 is electrically connected to the end portion 6a of the plurality of cathode portions 6 and the end portion 13a of the plurality of adhesive layers 13 exposed from the exterior body 14. The plurality of end portions 6a and end portions 13a are each exposed from the second side surface 14b of the exterior body 14 and have an end surface flush with the second side surface 14b.

[0043] The cathode-side external electrode 16 has a cathode-side first electrode layer 16a that covers the second side surface 14b of the exterior body 14 together with the end surfaces of the plurality of end portions 6a and end portions 13a exposed from the exterior body 14, and a cathode-side second electrode layer 16b formed on the surface of the cathode-side first electrode layer 16a. As the cathode-side external electrode, those that can be used as the anode-side external electrode can be used.

[0044] By connecting the ends 6a of the plurality of cathode portions 6 exposed from the outer package 14 to the external electrodes 16 respectively, a connection state with low resistance and high reliability can be obtained between the external electrode on the cathode side and the cathode portion.

[0045] In addition, in this embodiment, although the end 13a on the second end 2a side of the adhesive layer 13 is exposed from the outer package 14, the end 13a on the second end side of the adhesive layer 13 may be covered by the outer package 14.

[0046] Also, as another mode of the electrical connection between the external electrode 16 on the cathode side and the cathode portion 6, the main surface (a surface perpendicular to the stacking direction) of the cathode portion located at one end in the stacking direction of the plurality of capacitor elements and the external electrode on the cathode side may be electrically connected via a conductive adhesive layer. In this case, without exposing the ends 13a and 6a from the outer package, the main surface of the cathode portion may be exposed from a side surface other than the first side surface of the outer package.

[0047] [Manufacturing Method of Electrolytic Capacitor] Hereinafter, each step of the manufacturing method of the electrolytic capacitor according to the embodiment of the present invention will be described. (First Step) In the first step, a capacitor element having an anode lead-out portion and a cathode forming portion, a dielectric layer formed on the cathode forming portion, and a cathode portion covering at least a part of the dielectric layer is formed. The first step includes, for example, a step a1 of roughening the surface of the anode foil and a step a2 of forming a dielectric layer on the roughened surface of the anode foil. By steps a1 and a2, an anode foil having a dielectric layer formed on its surface is formed. A partial region including one end of the anode foil is used as the anode lead-out portion, and a region including the end (second end) of the anode foil on the side opposite to the end is used as the cathode forming portion. In step a1, at least the surface of the cathode forming portion of the anode foil may be roughened. Also, in step a2, a dielectric layer may be formed on at least the surface of the cathode forming portion of the anode foil. Since the external electrode is joined to the end face of the anode lead-out portion, the entire surface of the anode foil including the anode lead-out portion may be roughened and a dielectric layer may be formed.

[0048] ​The roughening of the surface of the anode foil only needs to be able to form irregularities on the surface of the anode foil. For example, it may be performed by etching (e.g., electrolytic etching) the surface of the anode foil.

[0049] The dielectric layer is formed by anodizing the anode foil. Anodization can be performed by a known method, such as a forming process. The forming process can be performed, for example, by immersing the anode foil in a forming solution to impregnate the surface of the anode foil with the forming solution, and applying a voltage between the anode foil as the anode and a cathode immersed in the forming solution. As the forming solution, for example, an aqueous phosphoric acid solution is preferably used.

[0050] When the surface of the anode foil is roughened, the dielectric layer is formed along the irregular shape of the roughened surface of the anode foil. That is, the surface of the dielectric layer has an irregular shape corresponding to the shape of the roughened surface of the anode foil.

[0051] Next, an insulating member (corresponding to the separation layer 12 in FIG. 1) is disposed on a part of the anode foil. More specifically, the insulating member is disposed directly on the anode lead-out portion of the anode foil or via the dielectric layer. The insulating member is disposed so as to isolate the anode lead-out portion from the cathode portion formed in a subsequent process.

[0052] The insulating member may be a sheet-like insulating member (such as a resin tape) attached to the anode lead-out portion while pressing it together with the anode lead-out portion. In addition to the above, an insulating member may be formed by applying or impregnating a resin solution as a raw material solution to the anode lead-out portion. After applying or impregnating the resin solution, the solvent may be removed by heating and drying or the like.

[0053] Subsequently, a cathode portion is formed on the anode foil where the insulating member is not disposed to obtain a capacitor element. More specifically, at least a part of the dielectric layer formed on the surface of the cathode forming portion of the anode foil is covered with the cathode portion.

[0054] The step of forming the cathode portion includes, for example, a step of forming a solid electrolyte covering at least a part of the dielectric, and a step of forming a cathode lead-out layer covering at least a part of the solid electrolyte layer.

[0055] The solid electrolyte layer can be formed, for example, by chemically polymerizing and / or electrolytically polymerizing a raw material monomer on the dielectric layer. Also, the solid electrolyte layer may be formed by attaching a treatment liquid containing a conductive polymer and then drying it. The treatment liquid may further contain other components such as a dopant. For example, poly(3,4-ethylenedioxythiophene) (PEDOT) is used as the conductive polymer. For example, polystyrene sulfonic acid (PSS) is used as the dopant. The treatment liquid is a dispersion or solution of a conductive polymer. Examples of the dispersion medium (solvent) include water, an organic solvent, or a mixture thereof.

[0056] The cathode lead-out layer can be formed, for example, by sequentially laminating a carbon layer and a silver paste layer on the solid electrolyte layer.

[0057] (Second step) In the second step, the capacitor element is covered with an exterior body. The exterior body can be formed using a molding technique such as injection molding. The exterior body is, for example, filled with a curable resin composition or a thermoplastic resin (composition) at a predetermined location so as to cover the capacitor element using a predetermined mold and can be formed.

[0058] The curable resin composition may contain, in addition to the curable resin, a filler, a curing agent, a polymerization initiator, and / or a catalyst, etc. Examples of the curable resin include a photocurable resin and a thermosetting resin. The curing agent, polymerization initiator, catalyst, etc. are appropriately selected according to the type of the curable resin.

[0059] (Third step) In the third step, after the second step, the exterior body is cut together with the anode lead-out portion to form a first end portion having an end face exposed from the cut surface of the exterior body on the anode lead-out portion. Thereby, the end face of the anode foil flush with one side surface of the exterior body can be easily exposed from the exterior body, respectively.

[0060] By the third step, the end face of the anode foil (first end portion) can be easily exposed from the exterior body, and a connection state with low resistance and high reliability can be obtained between the anode foil (anode lead-out portion) and the external electrode.

[0061] (Fourth step) In the fourth step, a part of the exterior body exposed at the cut surface of the exterior body is removed, and the first end portion is projected from the end face of the exterior body. As a method of removing a part of the exterior body, it is preferable to use a blasting process. Since the exterior body is a material softer than the core portion of the anode foil, the exposed portion of the exterior body is selectively removed by the blasting process. As a result, the first end portion of the anode lead-out portion projects from the end face of the exterior body. As the blasting process, a method of spraying resin, ceramics, and metal powder onto the cut surface of the exterior body can be used.

[0062] In the first step, it is also conceivable that the surfaces of the anode lead-out portion and the cathode forming portion are roughened, respectively, and a dielectric layer is formed on the surface of the anode lead-out portion. In that case, the exposed portion of the porous portion (dielectric layer) is also selectively removed, and the first end portion of the anode lead-out portion projects from the end face of the exterior body. In the vicinity of the first end portion, there may be a region where the core portion of the anode lead-out portion where the porous portion is not formed on the anode lead-out portion is exposed.

[0063] (Fifth step) In the fifth step, the protruding first end is joined to the external electrode. The external electrode on the anode side preferably includes the first electrode layer and the second electrode layer on the anode side. The step of forming the external electrode on the anode side preferably includes a step of covering at least a part of the end face of the exterior body together with at least a part of the first end protruding from the exterior body with the first electrode layer on the anode side, and a step of forming the second electrode layer on the anode side on the surface of the first electrode layer on the anode side. As the first electrode layer and the second electrode layer on the anode side, those exemplified above can be used.

[0064] (Sixth step) Furthermore, a sixth step of joining the cathode portion to the external electrode on the cathode side may be performed. As the external electrode on the cathode side, those exemplified for the external electrode on the anode side can be used. When manufacturing an electrolytic capacitor having the structure shown in FIG. 1, the ends on the second end side of the plurality of cathode portions exposed from the exterior body and the ends on the second end side of the plurality of adhesive layers may be joined to the external electrode on the cathode side. In this case, in the second step, the exterior body may be formed such that the ends on the second end side of the plurality of cathode portions and the ends on the second end side of the adhesive layer are exposed.

[0065] In addition to the above, before the second step and after the first step, the main surface (the surface perpendicular to the stacking direction) of the cathode portion located at either end in the stacking direction of the plurality of capacitor elements may be joined to the external electrode on the cathode side.

Industrial Applicability

[0066] The electrolytic capacitor according to the present invention can be used in various applications that require excellent sealing properties even when exposed to a high-humidity atmosphere.

Explanation of Reference Numerals

[0067] 1: Anode lead-out portion, 1a: First end portion, 2: Cathode formation portion, 2a: Second end portion, 3: Anode foil, 4: Core portion, 5: Porous portion, 6: Cathode portion, 6a: End portion on the second end side of the cathode portion, 7: Solid electrolyte layer, 8: Carbon layer, 9: Silver paste layer, 10: Capacitor element, 11: Electrolytic capacitor, 12: Separation layer, 13: Adhesive layer, 13a: End portion on the second end side of the adhesive layer, 14: Outer package, 14a: First side surface of the outer package, 14b: Second side surface of the outer package, 15: External electrode on the anode side, 15a: First electrode layer on the anode side, 15b: Second electrode layer on the anode side, 16: External electrode on the cathode side, 16a: First electrode layer on the cathode side, 16b: Second electrode layer on the cathode side

Claims

1. An anode foil having an anode lead-out portion including a first end portion and a cathode forming portion including a second end portion, a dielectric layer formed on the surface of the cathode forming portion, a cathode portion covering at least a part of the dielectric layer, a capacitor element having the above, an exterior body for sealing the capacitor element, and an external electrode, wherein the anode lead-out portion and the cathode forming portion each have a core portion and a porous portion formed on the surface of the core portion, the first end portion of the anode lead-out portion has a protruding portion formed to protrude from an end face of the exterior body, the external electrode includes a first electrode layer and a second electrode layer electrically connected to the anode lead-out portion, the first electrode layer contains nickel, the second electrode layer contains tin, an electrolytic capacitor in which upper and lower surfaces of the protruding portion in the stacking direction of the capacitor element and the end face of the exterior body are in direct contact with the first electrode layer.

2. An anode foil having an anode lead-out portion including a first end portion and a cathode forming portion including a second end portion, a dielectric layer formed on the surface of the cathode forming portion, a cathode portion covering at least a part of the dielectric layer, a capacitor element having the above, an exterior body for sealing the capacitor element, and an external electrode, wherein the anode lead-out portion and the cathode forming portion each have a core portion and a porous portion formed on the surface of the core portion, the first end portion of the anode lead-out portion has a protruding portion formed to protrude from an end face of the exterior body, the external electrode includes a first electrode layer and a second electrode layer electrically connected to the anode lead-out portion, the first electrode layer contains nickel, the second electrode layer contains tin, an electrolytic capacitor in which upper and lower surfaces of the protruding portion in the stacking direction of the capacitor element are in direct contact with the first electrode layer.

3. The electrolytic capacitor according to claim 1 or 2, wherein upper and lower surfaces of the protruding portion in the stacking direction of the capacitor element and the end face of the exterior body are not in contact with the second electrode layer.

4. The electrolytic capacitor according to claim 1 or 2, wherein a protruding length of the protruding portion protruding from an end face of the exterior body is longer than a thickness of the first electrode layer.

5. The electrolytic capacitor according to claim 1 or 2, wherein the external electrode includes a third electrode electrically connected to a main surface of the cathode portion located at either one end in the stacking direction of the capacitor element via a conductive adhesive layer.

Images