Solid electrolytic capacitor and connection element of solid electrolytic capacitor

Abstract

This solid electrolytic capacitor comprises a laminate of solid electrolytic capacitor elements, a sealing body, a first external electrode, and a second external electrode. The solid electrolytic capacitor elements are provided with: a valve action metal base having a dielectric layer on at least one main surface, the valve action metal base being divided into an anode terminal region and a cathode formation region; and a solid electrolyte layer provided on the dielectric layer in the cathode formation region. The sealing body seals, using an insulating resin, the laminate in which the plurality of solid electrolytic capacitor elements are laminated. The first external electrode has a side surface electrode portion disposed on a first-side surface of the sealing body, and a folded portion linked to the side surface electrode portion, the first external electrode being connected to the anode terminal region. The second external electrode is connected to the cathode formation region. The folded portion of the first external electrode has a first portion, a second portion linked to the first portion, and a third portion linked to the second portion. The second portion is folded back so as to have a first angle with respect to the first portion. The third portion is bent so as to have a second angle with respect to the second portion. In a plan view in the lamination direction of the laminate, the second portion and the third portion overlap the first portion in the length direction of the first portion. The third portion has a junction surface that abuts the anode terminal region, whereby the first external electrode is connected to the anode terminal region on a surface.

Description

Solid electrolytic capacitor and connection element for solid electrolytic capacitor

[0001] The present invention relates to a solid electrolytic capacitor having a lead frame (connection element) as an external electrode.

[0002] Various techniques for connecting the anode foil of a laminate formed by stacking multiple capacitor elements to a lead frame have been known. For example, when a lead frame is formed on the bottom surface of a solid electrolytic capacitor, the anode foil is bent to be joined to the lead frame. When the anode foil is bent to be joined to the lead frame in this manner, the anode foil may be subjected to stress at the bending point (break point), which may cause it to break. To address these issues, a structure in which the lead frame is shaped to be close to the anode foil has been investigated.

[0003] The lead frame described in Patent Document 1 is folded back 180 degrees along the end surface electrodes of the solid electrolytic capacitor and bent in the lamination direction, and the anode lead portion of the solid electrolytic capacitor is joined at a surface extending in the lamination direction.

[0004] The lead frame described in Patent Document 2 has an anode terminal portion, a rising portion, and a bent portion. The rising portion is connected to the anode terminal portion. The rising portion is bent in the stacking direction. The bent portion is connected to the rising portion and bent in the direction in which the anode terminal portion protrudes. The bent portion is connected to the anode lead portion. In this manner, the lead frame is connected to the anode lead portion of the solid electrolytic capacitor.

[0005] JP 2014-204059 A JP 2009-218502 A

[0006] The lead frame in Patent Document 1 is folded back 180 degrees from a bending point. This means that a load is applied to the lead frame at this bending point, potentially resulting in breakage. Furthermore, the lead frame and the anode lead of the solid electrolytic capacitor are joined at a plane (cross section of the lead frame) that is perpendicular to the stacking direction, and the bonded surface has a very small bonded area. When the solid electrolytic capacitor bends and an elongation stress is applied in the stacking direction, stress is likely to be applied to the bonded surface. Therefore, the bonded surface with a very small bonded area is fragile and prone to breakage.

[0007] Furthermore, the lead frame of Patent Document 2 has a rising portion along the stacking direction, similar to Patent Document 1. In other words, when tensile stress is applied in the stacking direction, the lead frame is likely to be subjected to the tensile stress. The lead frame and the anode terminal are joined by linear contact. Therefore, the joining surface is very small and fragile, and there is a risk of breakage at the joined portion due to linear contact.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a highly reliable solid electrolytic capacitor in which the bonding strength between the anode terminal of the capacitor element and the connection element of the solid electrolytic capacitor is improved.

[0009] The solid electrolytic capacitor of the present invention comprises a laminate of solid electrolytic capacitor elements, a sealing body, a first external electrode, and a second external electrode. The solid electrolytic capacitor element comprises a valve metal substrate having a dielectric layer on at least one main surface thereof and divided into an anode terminal region and a cathode formation region, and a solid electrolyte layer provided on the dielectric layer in the cathode formation region. The sealing body seals the laminate of multiple stacked solid electrolytic capacitor elements with an insulating resin.

[0010] The first external electrode has a side electrode portion disposed on a first side surface of the sealing body and a folded portion connected to the side electrode portion, and is connected to the anode terminal area. The second external electrode is connected to the cathode formation area. The folded portion of the first external electrode has a first portion, a second portion connected to the first portion, and a third portion connected to the second portion. The second portion is folded back at a first angle relative to the first portion. The third portion is bent at a second angle relative to the second portion. When viewed in a plane in the stacking direction of the laminate, the second and third portions overlap with the first portion in the length direction of the first portion. The third portion has a joining surface that abuts the anode terminal area, so that the first external electrode is connected to the anode terminal area by a surface.

[0011] In this configuration, the first external electrode, which serves as a connecting element (lead frame) of the solid electrolytic capacitor, is folded back at a first angle and a second angle. The third portion and the anode terminal region are joined via a joint surface. These angles cause the first external electrode to be inclined with respect to the stacking direction of the laminate. In other words, when tensile stress is applied in the stacking direction, this angle can absorb the tensile stress. This improves the joint strength between the first external electrode and the anode terminal region, thereby preventing peeling or breakage at the joint surface.

[0012] The connection element (lead frame) for a solid electrolytic capacitor of the present invention includes a folded portion and a side electrode portion connected to the folded portion. The folded portion has a first portion, a second portion connected to the first portion, and a third portion connected to the second portion. The second portion is folded back at a first angle of 10° to 80° relative to the first portion. The third portion is bent at a second angle of 90° to 180° relative to the second portion. The second and third portions overlap with the first portion in a plan view perpendicular to the longitudinal direction.

[0013] In this configuration, the lead frame is folded back at a first angle and a second angle. The lead frame is joined to the anode terminal region of the laminate of the solid electrolytic capacitor at these angles. In this case, the lead frame is inclined with respect to the stacking direction of the laminate. In other words, when tensile stress is applied in the stacking direction, this angle can absorb the tensile stress. In other words, the bonding strength between the first external electrode and the anode terminal region is improved, and peeling or breakage at the bonding surface can be suppressed.

[0014] According to the present invention, it is possible to provide a highly reliable solid electrolytic capacitor in which the bonding strength between the anode terminal of the capacitor element and the lead frame is improved.

[0015] FIG. 1(A) is an external perspective view of the solid electrolytic capacitor according to the first embodiment, and FIG. 1(B) is a cross-sectional view of the solid electrolytic capacitor according to the first embodiment. FIG. 2(A) is an enlarged view of a portion of the capacitor element according to the first embodiment, and FIG. 2(B) is a cross-sectional view of the capacitor element. FIG. 3(A) is an external view of a first external electrode, and FIG. 3(B) is a cross-sectional view of the first external electrode. FIGS. 4(A) and 4(B) are cross-sectional views of the first external electrode according to the first embodiment. FIG. 5(A) is a schematic diagram showing the joint structure between the first external electrode and the anode terminal region according to the first embodiment, and FIG. 5(B) is a schematic diagram showing the joint structure between the first external electrode and the anode terminal region in a comparative configuration. FIG. 6 is a cross-sectional view of the first external electrode according to the second embodiment.

[0016] [First Embodiment] A solid electrolytic capacitor 1 according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1(A) is an external perspective view of the solid electrolytic capacitor according to the first embodiment, and Fig. 1(B) is a cross-sectional view of the solid electrolytic capacitor according to the first embodiment.

[0017] (Structure of Solid Electrolytic Capacitor) The solid electrolytic capacitor 1 comprises a capacitor assembly 10, a first external electrode 20, a second external electrode 30, and an insulating resin body 40. The first external electrode 20 comprises a side electrode portion 210 and a folded portion 220. Note that in Figures 1(A) and 1(B), for ease of understanding, some components are omitted, and the insulating resin body 40 is shown transparently. Furthermore, in each of the drawings of the present invention, each component is depicted in an exaggerated manner to more clearly explain the structure of the solid electrolytic capacitor 1.

[0018] As shown in FIGS. 1A and 1B, the capacitor assembly 10 includes a plurality of capacitor elements 11 and a conductive member 19. The conductive member 19 is preferably an electrode paste containing, for example, nickel, silver, or copper as a main component. The maximum thickness of the conductive member 19 is preferably 2 μm or more and 20 μm or less. Note that the conductive member 19 can be omitted if conductivity equal to or greater than the desired conductivity can be obtained between the plurality of capacitor elements 11 without using the conductive member 19. The stacking direction of the plurality of capacitor elements 11 in the capacitor assembly 10 corresponds to the Z-axis direction in FIGS. 1A and 1B.

[0019] In this embodiment, there is no limitation on the number of capacitor elements 11 that make up the capacitor assembly 10, as long as they are plural. The structure of the capacitor elements 11 will be described in detail later.

[0020] The plurality of capacitor elements 11 are stacked. A capacitor assembly 10 (laminate) is formed by stacking the plurality of capacitor elements 11. At this time, the plurality of capacitor elements 11 are formed so as to be approximately parallel to each other.

[0021] The capacitor assembly 10 is sealed with an insulating resin body 40. This forms a sealed body 400. The sealed body 400 has a generally rectangular parallelepiped shape having a top surface 401, a bottom surface 402, a first surface 403, a second surface 404, a third surface 405, and a fourth surface 406. The first surface 403 is a surface opposite to the second surface 404, and the third surface 405 is a surface opposite to the fourth surface 406. The first surface 403 corresponds to the "first side surface" in the present invention.

[0022] The first external electrode 20 is formed along a portion of the sealing body 400 and the capacitor element 11. Specifically, the side electrode portion 210 of the first external electrode 20 is disposed on the first surface 403 of the sealing body 400. A portion of the folded portion 220 of the first external electrode 20 is disposed on the bottom surface 402 of the sealing body 400. A more detailed structure and joining structure of the first external electrode 20 will be described later. The first external electrode 20 corresponds to the "connection element" in the present invention.

[0023] The first external electrode 20 is made of, for example, a copper alloy or iron alloy material. The side electrode portion 210 and the folded portion 220 are physically and electrically connected. The first external electrode 20 is made of, for example, a material cut out from a metal plate.

[0024] The side electrode portion 210 and the folded portion 220 may be integrally formed, and are preferably formed from a metal material that is easy to bend and has high conductivity. In this case, the first external electrode 20 is preferably arranged so as to be folded along the first surface 403 and the bottom surface 402 of the sealing body 400. The connection structure between the capacitor element 11 and the first external electrode 20 will be described in detail later.

[0025] The second external electrode 30 is formed along the sealing body 400. Specifically, the second external electrode 30 is disposed across the second surface 404 and the bottom surface 402. The capacitor element 11 and the second external electrode 30 are joined together with a conductive adhesive (not shown) made of silver paste or the like.

[0026] The cathode-side connection layers (conductive layers including the solid electrolyte layer 113) of the plurality of capacitor elements 11 are electrically and physically connected to the second external electrode 30 by a conductive adhesive.

[0027] The second external electrode 30 is preferably formed from a metal material that is easy to bend and has high conductivity, such as a copper alloy or iron alloy. The second external electrode 30 is formed from a material cut out from a metal plate, for example. The first external electrode 20 and the second external electrode 30 may be made of the same material or different materials.

[0028] The insulating resin body 40 is mainly made of resin and may contain a filler. Examples of preferred resins include epoxy resin, phenol resin, polyimide resin, silicone resin, polyamide resin, and liquid crystal polymer. The resin may be in either solid or liquid form. It is preferred that corners are rounded by barrel polishing after resin sealing. Examples of preferred fillers include silica particles and alumina particles. The maximum diameter of the filler is preferably 30 μm or more and 40 μm or less. A material containing silica particles in a solid epoxy resin and phenol resin is more preferred.

[0029] (Structure of Capacitor Element) The structure of capacitor element 11 will be described in more detail with reference to FIGS. 2(A) and 2(B).

[0030] Fig. 2(A) is a plan view of capacitor element 11, and Fig. 2(B) is a cross-sectional view of capacitor element 11. Fig. 2(B) is a cross-sectional view taken along a plane (XZ plane) perpendicular to the flat film surface and end surface of capacitor element 11.

[0031] Capacitor element 11 includes electrode foil 111, dielectric layer 112, solid electrolyte layer 113, carbon layer 114, and metal layer 115. Electrode foil 111 includes electrode layer 111F and porous layer 111L.

[0032] A more specific structure of the electrode foil 111 is as follows. The electrode layer 111F is made of, for example, a metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, or silicon, or an alloy containing these metals. The electrode layer 111F is preferably made of aluminum or an aluminum alloy. A porous layer 111L is formed on the surface of the electrode layer 111F. The porous layer 111L is formed by etching the surface of the electrode layer 111F. This makes the porous layer 111L porous. The electrode foil 111 may be made of a valve metal that exhibits so-called valve action.

[0033] A dielectric layer 112 is formed on the electrode foil 111. As shown in FIGS. 2A and 2B , the electrode foil 111 has a first surface F1 and a second surface F2 that face each other in the Z-axis direction. The electrode foil 111 further includes a third surface F3, a fourth surface F4, a fifth surface F5, and a sixth surface F6 that are connected to the first surface F1 and the second surface F2 and parallel to the Z-axis direction. The third surface F3 and the fourth surface F4 are parallel to the Y-axis direction. The fifth surface F5 and the sixth surface F6 are parallel to the X-axis. The dielectric layer 112 covers the first surface F1, the second surface F2, the fourth surface F4, the fifth surface F5, and the sixth surface F6 of the electrode foil 111.

[0034] The dielectric layer 112 is preferably made of an oxide film of the electrode foil 111 (porous layer 111L). For example, when an aluminum foil is used for the electrode layer 111F, the dielectric layer 112 is formed by applying a voltage in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or their sodium salts or ammonium salts, and then anodizing the aluminum foil. The thickness of the dielectric layer 112 is preferably 10 nm or more and 100 nm or less.

[0035] Solid electrolyte layer 113 covers the outer surface of dielectric layer 112 (at least the surface opposite to the surface in contact with electrode foil 111). Solid electrolyte layer 113 also fills the numerous pores covered with dielectric layer 112.

[0036] More specifically, the solid electrolyte layer 113 includes, for example, an inner layer and an outer layer.

[0037] The inner layer is a layer of solid electrolyte layer 113 that abuts dielectric layer 112, and may be, for example, a PEDOT:PSS layer realized by a conductive polymer having a skeleton of pyrroles, thiophenes, anilines, or the like, or a conductive polymer having a skeleton of thiophenes such as PEDOT [poly(3,4-ethylenedioxythiophene)], and composited with polystyrene sulfonic acid (PSS) as a dopant. The inner layer is formed by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of dielectric layer 112 using an electrolyte solution that serves as the base for forming solid electrolyte layer 113, for example, a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or a method of applying a dispersion of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric portion and drying it.

[0038] The outer layer is a layer formed on the outside of the inner layer. For example, the outer layer is formed so as to cover the entire surface of the inner layer after the inner layer is formed to fill the fine recesses in the porous portion. The thickness of the outer layer is preferably 2 μm or more and 20 μm or less. The outer layer is formed by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of the inner layer using an electrolyte solution that serves as the base for forming the solid electrolyte layer 113, for example, a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or a method of applying a dispersion or paste of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the inner layer portion and drying it, or the like.

[0039] A conductive member may be provided as a layer subsequent to the outer layer. The conductive member may include, for example, a carbon layer and a silver layer. The carbon layer is preferably formed by applying a conductive paste containing a mixture of an insulating resin such as epoxy resin or phenolic resin and particles of carbon black or graphite. The silver layer is preferably formed by applying a conductive paste containing a mixture of an insulating resin such as epoxy resin or phenolic resin and particles of silver or the like. The materials constituting the conductive member may be appropriately combined, for example, by omitting the carbon layer.

[0040] The carbon layer 114 is formed so as to cover the outer layer (solid electrolyte layer 113). The carbon layer 114 contains a thermosetting resin. More specifically, the carbon layer 114 is formed by applying a carbon paste in which an insulating resin such as a phenolic resin is mixed with particles of carbon black or graphite.

[0041] The metal layer 115 is formed so as to cover the carbon layer 114. The metal layer 115 includes a thermoplastic resin. More specifically, the metal layer 115 is formed by applying a metal paste in which an insulating resin such as a phenolic resin is mixed with silver particles, for example.

[0042] With this configuration, capacitor element 11 becomes a flat-film solid electrolytic capacitor. In this capacitor element 11, electrode foil 111 corresponds to the anode, and solid electrolyte layer 113 corresponds to the cathode. The region of electrode foil 111 where solid electrolyte layer 113 is not formed corresponds to the "anode terminal region" in the present invention, and solid electrolyte layer 113 corresponds to the "cathode-forming region" in the present invention. Electrode foil 111 corresponds to the "main body" in the present invention.

[0043] (Detailed Structure of First External Electrode) Next, the structure of the first external electrode 20 will be described in detail using Figures 3(A), 3(B), 4(A), and 4(B). Figure 3(A) is an external view of the first external electrode, and Figure 3(B) is a cross-sectional view of the first external electrode in the XZ plane. Figures 4(A) and 4(B) are cross-sectional views of the first external electrode in the XZ plane according to the first embodiment. Figures 4(A) and 4(B) show the structure of only the folded portion 220.

[0044] As shown in FIGS. 3A and 3B , the first external electrode 20 includes a side electrode portion 210 and a folded portion 220. As described above, the side electrode portion 210 and the folded portion 220 are configured by bending a metal plate midway along the length of the sealing body 400. The folded portion 220 includes a first portion 221, a second portion 222, and a third portion 223. The first portion 221 is substantially perpendicular to the side electrode portion 210. It is preferable that the first portion 221, the second portion 222, and the third portion 223 of the folded portion 220 of the first external electrode 20 have the same widthwise length in the Y-axis direction. However, the widthwise lengths do not have to be the same as long as the performance of the solid electrolytic capacitor 1 is not degraded.

[0045] The side electrode portion 210 is connected to a first portion 221. The first portion 221 is connected to a second portion 222. The second portion 222 is connected to a third portion 223. The anode terminal region and the folded portion 220 are joined by the third portion 223. The surface where the third portion 223 and the anode terminal region abut corresponds to the joining surface. In other words, the folded portion 220 has a folded shape with two bending points.

[0046] In this case, the first portion 221 and the third portion 223 have portions that run parallel to each other with a predetermined gap between them. More specifically, in a plan view (in the Z-axis direction) from the top surface 401 side, the first portion 221 and the third portion 223 have portions that run parallel to each other with a predetermined gap between them. In this case, it is preferable that the maximum value of the shortest distance H1 between the first portion 221 and the third portion 223 in the Z-axis direction is 0.1 mm or more.

[0047] As shown in FIG. 4A , the first portion 221 and the second portion 222 are connected in a bent shape that forms a first angle α1 in the longitudinal direction. The first angle α1 is an acute angle. More specifically, the first angle α1 is greater than 0° and less than 90°. More preferably, the first angle α1 is greater than 10° and less than 80°. By having the first angle α1, the first external electrode 20 has a portion that is inclined with respect to the Z-axis direction (stacking direction). In other words, even if tensile stress is applied to the solid electrolytic capacitor 1, the stress is absorbed by this inclination. Therefore, damage to the first external electrode 20 is suppressed.

[0048] 4A, the second portion 222 and the third portion 223 are connected in a bent shape so as to form a second angle α2 in the longitudinal direction. The second angle α2 is an obtuse angle. More specifically, the second angle α2 is preferably greater than 90° and less than 180°.

[0049] In this way, since the first external electrode 20 has the second angle α2, the plane including the X axis and the third portion 223 are disposed so as to form the third angle β shown in FIG. 4B . In this case, the plane including the X axis corresponds to the “reference plane” in the present invention. The reference plane is a plane parallel to the bottom surface of the laminate.

[0050] The third angle β is preferably greater than 0° and less than 5°. That is, the second angle α2 is preferably determined so that the third angle β is greater than 0° and less than 5°.

[0051] 4B , one end of the third portion 223 that is connected to the second portion 222 is designated as P1, and the other end that is not connected to the second portion 222 is designated as P2. In the Z-axis direction, the other end P2 is disposed farther away from the first portion 221 than the one end P1. This state is a state in which the third angle β has a positive value. On the other hand, in the third portion 223, a state in which the other end P2 is closer to the first portion 221 in the Z-axis direction than the one end P1 is a state in which the third angle β has a negative value.

[0052] (Joint Structure Between First External Electrode and Anode Terminal Region) Next, the joint structure between the first external electrode and the anode terminal region will be described in more detail with reference to Fig. 5(A). Fig. 5(A) is a schematic diagram showing the joint structure between the first external electrode and the anode terminal region according to the first embodiment, and Fig. 5(B) is a schematic diagram showing the joint structure between the first external electrode and the anode terminal region in a comparative configuration. Note that Figs. 5(A) and 5(B) schematically show a portion of the anode terminal region of the capacitor assembly 10.

[0053] As shown in FIG. 5A , the third portion 223 in the first embodiment is formed to have a third angle β with respect to a plane including the X-axis. In the pre-bonding state shown in FIG. 5A , the third portion 223 and the anode terminal region are bonded. In the post-bonding state shown in FIG. 5A , the third portion 223 bends along the anode terminal region due to pressure, etc., applied when the anode terminal region is heated and pressurized. Therefore, the third portion 223 is bonded in a state where it is positioned along the anode terminal region. In other words, the third portion 223 and the anode terminal region are surface-bonded. It is preferable that the third angle β remains at a certain value or greater even after bonding.

[0054] On the other hand, as shown in FIG. 5B , the angle βp between the third portion and the plane including the X-axis in the comparative configuration is smaller than 0°. In this state, the third portion 223P and the anode terminal region are joined. In this case, the anode terminal region contacts the edge where the third portion 223P and the second portion 222P are connected. Therefore, in the joined state shown in FIG. 5B , the third portion 223 does not align with the anode terminal region. Therefore, the third portion 223P and the anode terminal region are linearly joined.

[0055] Therefore, when the third angle β is greater than 0° (a positive value) and smaller than 5°, the bonding area between the third portion 223 and the anode terminal region is increased, thereby improving the bonding strength between the first external electrode 20 and the anode terminal region.

[0056] In this way, the first external electrode 20 has the first angle α1, so that the first external electrode 20 has a structure inclined with respect to the Z-axis direction. That is, even if tensile stress is applied to the solid electrolytic capacitor 1, the stress is absorbed by this inclination. Therefore, damage to the first external electrode 20 is suppressed.

[0057] Furthermore, by providing a structure in which the third portion 223 has the second angle α2 and the third angle β with respect to the reference plane, the bonding area between the third portion 223 and the anode terminal region is increased, thereby improving the bonding strength between the first external electrode 20 and the anode terminal region. This improves the bonding strength between the first external electrode 20 and the anode terminal region, thereby realizing a highly reliable solid electrolytic capacitor 1.

[0058] Additionally, the maximum value (separation distance) of the shortest distance H1 between the first portion 221 and the third portion 223 in the Z-axis direction is 0.1 mm or more and 0.8 mm or less. Preferably, the distance H1 is 0.4 mm. For example, if the distance H1 is less than 0.1 mm, as in the conventional configuration, there is a risk that heat marks caused when joining the anode terminal region and the lead frame will be exposed on the bottom surface 402. The minute irregularities caused by these heat marks will reduce the sealing performance during the sealing process. In other words, there is a risk that resin leakage will occur due to the heat marks.

[0059] However, in the present invention, the distance H1 is 0.1 mm or more (see FIG. 3B ). That is, the heat marks on the bonding surface between the third portion 223 and the anode terminal region are not exposed on the bottom surface 402. This improves the appearance quality of the solid electrolytic capacitor 1. Furthermore, the formation of minute irregularities due to heat marks is suppressed, improving the sealing performance during the sealing process and suppressing resin leakage. Furthermore, because the distance between the first portion 221 and the third portion 223 is a predetermined distance or more (in this embodiment, 0.1 mm or more and 0.8 mm or less), the degree of freedom in the height position of the connection portion between the anode terminal region and the third portion 223 is increased, facilitating design.

[0060] 1A , the third portion 223 can be positioned to align with the anode terminal regions of the multiple capacitor elements aligned in the Z-axis direction (stacking direction). This reduces the average distance in the Z-axis direction between the anode terminal regions of the multiple capacitor elements and the bonding surface of the third portion 223. Furthermore, it reduces the distance between the bonding surface and the anode terminal region farthest from the bonding surface in the third portion 223. Therefore, the amount of bending of the anode terminal regions of the multiple capacitor elements can be reduced overall, thereby suppressing breakage due to bending of the anode terminal regions.

[0061] Furthermore, by setting the distance H1 to 0.8 mm or less, the solid electrolytic capacitor 1 can be made smaller while maintaining the appearance quality of the solid electrolytic capacitor 1.

[0062] Second Embodiment A solid electrolytic capacitor 1A according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 6 is a cross-sectional view of a first external electrode according to the second embodiment taken along the XZ plane.

[0063] 6, the solid electrolytic capacitor 1A according to the second embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in that the first external electrode includes a fourth portion 224. The other configuration of the solid electrolytic capacitor according to the second embodiment is the same as that of the solid electrolytic capacitor according to the first embodiment, and a description of the same parts will be omitted.

[0064] As shown in Fig. 6, the first external electrode 20A includes a side electrode portion 210 and a folded portion 220A. The side electrode portion 210 and the folded portion 220A are configured by bending a metal plate midway along the length of the sealing body 400. The folded portion 220A includes a first portion 221, a second portion 222, a third portion 223, and a fourth portion 224. The first portion 221, the second portion 222, and the third portion 223 of the folded portion 220A have the same configurations as the first portion 221, the second portion 222, and the third portion 223 of the folded portion 220. The third portion 223 is connected to the fourth portion 224.

[0065] 6, the third portion 223 and the fourth portion 224 are configured to be bent at a fourth angle α4 in the longitudinal direction. In this case, the fourth portion 224 extends from the third portion 223 (the other end P2 in FIG. 4B) toward the first portion 221. For example, the fourth angle α4 is preferably approximately 90°.

[0066] The fourth portion 224 is defined to have a length that does not contact the first portion 221. In other words, the length of the fourth portion 224 is preferably shorter than H1.

[0067] Even with this configuration, the first external electrode 20A has the first angle α1, so that the first external electrode 20A is inclined with respect to the Z-axis direction. That is, the tensile stress applied to the solid electrolytic capacitor 1A is absorbed by this inclination. Therefore, damage to the first external electrode 20A is suppressed.

[0068] Furthermore, by providing a structure in which the third portion 223 has the second angle α2 and the third angle β with respect to the reference plane, the bonding area between the third portion 223 and the anode terminal region is increased, thereby improving the bonding strength between the first external electrode 20A and the anode terminal region. This improves the bonding strength between the first external electrode 20A and the anode terminal region, thereby realizing a highly reliable solid electrolytic capacitor 1A.

[0069] Furthermore, distance H1 is 0.1 mm or more. That is, heat marks on the bonding surface between third portion 223 and the anode terminal region are not exposed on bottom surface 402. This improves the appearance quality of solid electrolytic capacitor 1A. Furthermore, the formation of minute irregularities due to heat marks is suppressed, improving the sealing performance during the sealing process and suppressing resin leakage. Furthermore, because the distance between first portion 221 and third portion 223 is a predetermined distance or more (0.1 mm or more and 0.8 mm or less), the degree of freedom in the height position of the connection portion between the anode terminal region and the third portion is increased, facilitating design.

[0070] Furthermore, the fourth portion 224 is formed to bend at a fourth angle α4 with respect to the third portion 223. As a result, even if an tensile stress is applied to the first external electrode 20A, the end portion of the fourth portion 224 that is not connected to the third portion 223 (the end portion of the first external electrode 20A) can suppress bending of the first external electrode 20A. In other words, the third portion 223 acts as a stopper to suppress excessive bending. That is, damage to the first external electrode 20A can be suppressed.

[0071] Furthermore, the configurations shown in the above-described embodiments can be combined as appropriate, and effects according to each combination can be achieved.

[0072] F1...first surface F2...second surface F3...third surface F4...fourth surface F5...fifth surface F6...sixth surface H1...distance 1, 1A...solid electrolytic capacitor 10...capacitor assembly 11...capacitor element 19...conductive member 20, 20A...first external electrode 30...second external electrode 40...insulating resin body 111...electrode foil 111F...electrode layer 111L...porous layer 112...dielectric layer 113...solid electrolyte layer 114...carbon layer 115...metal layer 210...side electrode portion 220, 220A...folded portion 221...first portion 222...second portion 223...third portion 224...fourth portion 400...sealing body 401...top surface 402...bottom surface 403...first surface 404...second surface 405...Third side 406...Fourth side

Claims

1. A laminate of solid electrolytic capacitor elements comprising: a valve action metal substrate having a dielectric layer on at least one main surface thereof and divided into an anode terminal region and a cathode formation region; and a solid electrolyte layer provided on the dielectric layer in the cathode formation region; a sealing body sealed with an insulating resin; a first external electrode having a side electrode portion disposed on a first side surface of the sealing body and a folded portion connecting to the side electrode portion, and connected to the anode terminal region; and a second external electrode connected to the cathode formation region, wherein the folded portion of the first external electrode has a first portion, a second portion connecting to the first portion, and a third portion connecting to the second portion, the second portion being folded back at a first angle relative to the first portion, and the third portion being bent at a second angle relative to the second portion, and when viewed in a plane in the stacking direction of the laminate, the second portion and the third portion overlap with the first portion in the length direction of the first portion, The third portion has a joining surface that abuts against the anode terminal area, so that the first external electrode is connected to the anode terminal area via a surface thereof.

2. The solid electrolytic capacitor of claim 1, wherein the first angle is an acute angle.

3. The solid electrolytic capacitor according to claim 1, wherein the first angle is equal to or greater than 10° and equal to or less than 80°, and the second angle is greater than 90° and less than 180°.

4. The solid electrolytic capacitor according to claim 1, wherein the bonding surface in the third portion has a third angle greater than 0° with respect to a reference plane parallel to the bottom surface of the laminate.

5. The solid electrolytic capacitor according to claim 4, wherein the third angle is less than 5°.

6. The solid electrolytic capacitor according to claim 1, wherein the distance between the first portion and the third portion in the stacking direction is 0.1 mm or more and 0.8 mm or less.

7. A solid electrolytic capacitor according to any one of claims 1 to 6, wherein the folded portion of the first external electrode has a fourth portion that is connected to the third portion in the longitudinal direction of the first external electrode, and the fourth portion is bent toward the first portion at a predetermined angle relative to the third portion.

8. A connection element for a solid electrolytic capacitor comprising a folded portion and a side electrode portion connected to the folded portion, wherein the folded portion has a first portion, a second portion connected to the first portion, and a third portion connected to the second portion, wherein the second portion is folded back to form a first angle of 10° or more and 80° or less with respect to the first portion, and the third portion is bent to form a second angle of 90° or more and less than 180° with respect to the second portion, and wherein the second portion and the third portion overlap with the first portion when viewed in a plane in a direction perpendicular to the longitudinal direction.

9. A connection element for a solid electrolytic capacitor according to claim 8, wherein the folded portion has a fourth portion connected to the third portion in the longitudinal direction, and the fourth portion is bent at a predetermined angle relative to the third portion.

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