Solid electrolytic capacitor

Abstract

This solid electrolytic capacitor comprises: a capacitor element having an anode part and a cathode part; a cathode lead frame; and an exterior body. The capacitor element has a lower surface and an upper surface on the side opposite the lower surface. The cathode lead frame includes: a cathode lead embedded part that is embedded inside the exterior body and is electrically connected to the cathode part; and a cathode lead exposed part that is exposed to the outside from a first end surface of the exterior body. The cathode lead embedded part includes: a first cathode lead part extending from the first end surface of the exterior body toward the capacitor element; a second cathode lead part extending downward from one end of the first cathode lead part; and a third cathode lead part extending from one end of the second cathode lead part along the lower surface of the capacitor element. The second cathode lead part has a first through hole. When a direction connecting the upper surface and the lower surface of the capacitor element is defined as the height direction, a length in the height direction of the second cathode lead part is defined as H1, and a length in the height direction of a portion between the third cathode lead part and a lowermost end of the first through hole of the second cathode lead part is defined as D1, the relationship of D1 / H1 ≤0.19 is satisfied.

Description

Solid electrolytic capacitor

[0001] The present invention relates to a solid electrolytic capacitor.

[0002] A solid electrolytic capacitor includes, for example, a capacitor element having an anode portion and a cathode portion, a cathode lead frame electrically connected to the cathode portion, and an outer package covering the capacitor element.

[0003] In Patent Document 1, a solid electrolytic capacitor is disclosed, in which an anode lead wire planted on one end face of an anode body of a capacitor element having a dielectric film layer, a solid electrolyte layer, and a cathode lead-out layer sequentially formed on the surface of an anode body made of a valve-acting metal is connected to an anode lead frame by resistance welding, and after the cathode lead-out layer and a cathode lead frame bent in a stepped shape are adhered with a conductive adhesive, they are covered with an outer resin. In this solid electrolytic capacitor, a tongue piece portion is formed by bending a part of the surface of the cathode lead frame that connects to the bottom surface of the capacitor element in a direction opposite to the stepped bending direction, and the tongue piece portion and the surface of the lead frame facing the capacitor element and the cathode lead-out layer are adhered with a conductive adhesive.

[0004] Japanese Patent Application Laid-Open No. 2007-149732

[0005] One aspect of the present invention relates to a solid electrolytic capacitor. The solid electrolytic capacitor comprises a capacitor element having an anode portion and a cathode portion, a cathode lead frame electrically connected to the cathode portion, and an outer casing covering the capacitor element. The capacitor element has a bottom surface, an upper surface opposite to the bottom surface, and two sides connecting the bottom surface and the upper surface. The cathode lead frame has a cathode lead embedding portion embedded inside the outer casing and electrically connected to the cathode portion, and a cathode lead exposure portion exposed to the outside from a first end surface of the outer casing. The cathode lead embedding portion has a first cathode lead portion extending from the first end surface of the outer casing toward the capacitor element, a second cathode lead portion extending downward from one end of the first cathode lead portion, and a third cathode lead portion extending from one end of the second cathode lead portion along the bottom surface of the capacitor element. The second cathode lead portion has a first through hole. When the direction connecting the upper surface and the lower surface of the capacitor element is defined as the height direction, the length of the second cathode lead portion in the height direction is H1, and the length of the portion between the lowest end of the first through hole in the second cathode lead portion and the third cathode lead portion in the height direction is D1, the relationship D1 / H1 ≤ 0.19 is satisfied.

[0006] According to this disclosure, it is possible to provide a solid electrolytic capacitor that can reduce the amount of moisture reaching the capacitor element from the outside of the outer casing.

[0007] This is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to one embodiment of the present disclosure. This is a front view showing the configuration of the cathode lead frame before it is connected to the capacitor element. This is a side view showing the configuration of the cathode lead frame before it is connected to the capacitor element. This is a top view illustrating an example of the configuration of the anode lead frame. This is a top view illustrating another example of the configuration of the anode lead frame. This is a flowchart illustrating a method for manufacturing a solid electrolytic capacitor according to one embodiment of the present disclosure.

[0008] In solid electrolytic capacitors, moisture that penetrates the casing can degrade the performance of the capacitor element. This degradation becomes more pronounced the greater the amount of moisture that reaches the capacitor element from the outside of the casing.

[0009] On the other hand, prior art such as Patent Document 1 has not yet sufficiently investigated how to reduce the amount of moisture reaching the capacitor element from the outside of the outer casing.

[0010] This disclosure provides a solid electrolytic capacitor that can reduce the amount of moisture reaching the capacitor element from the outside of the casing.

[0011] The embodiments of this disclosure will be described below with examples, but this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values, materials, etc. may be applied as long as the effects of this disclosure are obtained. Notwithstanding, known components may be applied to components of parts that are characteristic of this disclosure. In this specification, when "the range of numerical values ​​A to numerical values ​​B" is used, that range includes numerical values ​​A and B.

[0012] In the following explanation, when examples are given of lower and upper limits for specific physical properties or conditions, any combination of either of the given lower limits and any of the given upper limits is permitted, as long as the lower limit does not exceed the upper limit. When multiple materials are given as examples, unless otherwise specified, one type may be selected and used alone, or two or more types may be used in combination.

[0013] This disclosure includes any combination of two or more claims, which may be arbitrarily selected from the claims set forth in the attached claims. In other words, any combination of two or more claims, which may be arbitrarily selected from the claims set forth in the attached claims, is possible, provided that no technical inconsistency arises.

[0014] A solid electrolytic capacitor according to an embodiment of the present disclosure comprises a capacitor element having an anode portion and a cathode portion, a cathode lead frame electrically connected to the cathode portion, and an outer casing covering the capacitor element.

[0015] In the solid electrolytic capacitor according to the embodiment of this disclosure, the capacitor element has a lower surface, an upper surface opposite to the lower surface, and two sides connecting the lower surface and the upper surface, and the cathode lead frame has a cathode lead embedding portion embedded inside the outer casing and electrically connected to the cathode portion, and a cathode lead exposed portion exposed to the outside from one end surface (first end surface) of the outer casing.

[0016] In the solid electrolytic capacitor according to the embodiment of this disclosure, the cathode lead embedding portion includes a first cathode lead portion extending from one end face (first end face) of the outer casing toward the capacitor element, a second cathode lead portion extending downward from one end of the first cathode lead portion, and a third cathode lead portion extending from one end of the second cathode lead portion along the lower surface of the capacitor element, wherein the second cathode lead portion has a first through hole.

[0017] In the solid electrolytic capacitor according to the embodiment of this disclosure, when the direction connecting the upper and lower surfaces of the capacitor element is defined as the height direction, the length of the second cathode lead portion in the height direction is H1, and the length of the portion in the second cathode lead portion in the height direction between the lowest end of the first through hole and the third cathode lead portion is D1, the relationship D1 / H1 ≤ 0.19 is satisfied.

[0018] In the solid electrolytic capacitor according to the embodiment of this disclosure, it is important that the relationship D1 / H1 ≤ 0.19 is satisfied when H1 is the height length of the second cathode lead portion and D1 is the height length of the portion between the lowest end of the first through hole and the third cathode lead portion in the second cathode lead portion. In short, it is important that the lowest end of the first through hole is located close to the third cathode lead portion that extends along the lower surface of the capacitor element. The reason for this will be explained below.

[0019] As described above, a solid electrolytic capacitor comprises a capacitor element having an anode and a cathode, a cathode lead frame electrically connected to the cathode, and an outer casing covering the capacitor element. When the cathode lead embedded portion of the cathode lead frame has a first cathode lead portion extending from one end face of the outer casing toward the capacitor element, a second cathode lead portion extending downward from one end of the first cathode lead portion, and a third cathode lead portion extending from one end of the second cathode lead portion along the lower surface of the capacitor element, some of the moisture that enters the interior of the outer casing passes over the surface of the first cathode lead portion, then sequentially through the surface of the second cathode lead portion and the surface of the third cathode lead portion before reaching the capacitor element.

[0020] Capacitor elements have a solid electrolyte layer, which often contains conductive polymers. As described above, moisture that penetrates the casing and reaches the capacitor element degrades the solid electrolyte layer by oxidizing and degrading the conductive polymers and decomposing the dopants. When the solid electrolyte layer degrades, it leads to a decrease in capacitance and an increase in equivalent series resistance (ESR), thus reducing the performance of the solid electrolytic capacitor. Therefore, it is desirable to minimize the amount of moisture that penetrates the casing and reaches the capacitor element.

[0021] To reduce the amount of moisture reaching the capacitor element, it is conceivable to narrow the moisture transfer path within the casing. For example, it is conceivable to form a through-hole in at least one of the first cathode lead portion, the second cathode lead portion, and the third cathode lead portion to narrow the moisture transfer path in the cathode lead embedded portion. In this case, if a through-hole is formed in the first cathode lead portion, burrs may form on the casing if part of the through-hole is exposed to the outside of the casing, and if the entire through-hole is embedded inside the casing, resin chipping may occur inside the casing. Also, if a through-hole is formed in the third cathode lead portion, since the third cathode lead portion is close to the bottom surface of the casing, the conductive adhesive used to bond the bottom surface of the capacitor element and the third cathode lead portion may pass through the through-hole and be exposed to the outside of the casing, resulting in a cosmetic defect. Because of these new problems, it is undesirable to form through-holes in the first cathode lead portion and the third cathode lead portion. Therefore, it is conceivable to form a through-hole in the second cathode lead portion. On the other hand, simply providing a through-hole in the second cathode lead portion is insufficient. Moisture passing through the unformed portion of the through-hole can wrap around to the area between the lowest end of the through-hole and the third cathode lead portion before reaching the third cathode lead portion. Therefore, if the area between the lowest end of the through-hole and the third cathode lead portion is wide, the moisture transfer path is not sufficiently narrowed, and the amount of moisture reaching the capacitor element cannot be reduced.

[0022] In the solid electrolytic capacitor according to the embodiment of this disclosure, when the direction connecting the upper and lower surfaces of the capacitor element is defined as the height direction, the length of the second cathode lead portion in the height direction is H1, and the length of the portion in the second cathode lead portion between the lowest end of the first through hole and the third cathode lead portion in the height direction is D1, the relationship D1 / H1 ≤ 0.19 is satisfied. In short, the lowest end of the first through hole is located close to the third cathode lead portion which extends along the lower surface of the capacitor element. Therefore, in the second cathode lead portion, it is possible to suppress moisture that has passed through the unformed portion of the first through hole from flowing around to the portion between the lowest end of the first through hole and the third cathode lead portion before reaching the third cathode lead portion. That is, the moisture transfer path in the second cathode lead portion can be sufficiently narrowed. As a result, the amount of moisture that reaches the capacitor element can be reduced.

[0023] In the following, a solid electrolytic capacitor according to one embodiment of the present disclosure will be described with reference to the drawings. The solid electrolytic capacitor according to one embodiment of the present disclosure only needs to have at least one capacitor element. That is, the solid electrolytic capacitor according to one embodiment of the present disclosure may have one capacitor element or may have multiple capacitor elements. In the following, an example in which the solid electrolytic capacitor has one capacitor element will be described.

[0024] [Solid Electrolytic Capacitor] As shown in Figure 1, a solid electrolytic capacitor 100 according to one embodiment of the present disclosure includes a capacitor element 10 having an anode portion 6 and a cathode portion 7, a cathode lead frame 14 electrically connected to the cathode portion 7, and an outer casing 11 covering the capacitor element 10. The solid electrolytic capacitor 100 according to one embodiment of the present disclosure further includes an anode lead frame 13 electrically connected to the anode portion 6.

[0025] <Capacitor Element> The capacitor element 10 has a bottom surface B, an upper surface U opposite to the bottom surface B, and two side surfaces connecting the bottom surface B and the upper surface U. Note that Figure 1 is a cross-sectional view, so the side surfaces are not shown.

[0026] (Anode section) The anode section 6 includes an anode body 1, an anode wire 2 extending from one end face E1 of the anode body 1, and a dielectric layer 3. In the solid electrolytic capacitor 100 according to one embodiment of the present disclosure, as shown in Figure 1, the anode section 6 is electrically connected to the anode lead frame 13.

[0027] The anode 1 is, for example, a porous sintered body obtained by sintering metal particles. The anode 1 has, for example, a rectangular parallelepiped shape. As the metal particles, valve metal particles such as titanium (Ti), tantalum (Ta), and niobium (Nb) can be used. The anode 1 may be obtained by sintering one type of metal particle, or by sintering two or more types of metal particles. The metal particles may be alloy particles composed of two or more types of metals. As the alloy particles, for example, alloy particles containing a valve metal and at least one element selected from the group consisting of silicon, vanadium, and boron can be used. Alternatively, alloy particles containing a valve metal and a typical element (such as nitrogen) can also be used. The above alloy particles usually contain a valve metal as the main component. The above alloy particles, for example, contain 50 atomic percent or more of the valve metal.

[0028] The anode wire 2 is made of a conductive material. The material used to form the anode wire 2 is not particularly limited and can be, for example, the valve metal mentioned above, as well as copper, aluminum, and aluminum alloys. The material used to form the anode body and the material used to form the anode wire may be the same or different. The cross-sectional shape of the anode wire 2 is not particularly limited and can be circular, track-shaped, elliptical, rectangular, or polygonal. A track-shaped cross-section is a shape consisting of parallel straight lines and two curves connecting the ends of these lines.

[0029] The anode portion 6 can be manufactured, for example, by embedding the first portion 2a of the anode wire 2 in the metal particle powder, press-molding it into a rectangular parallelepiped shape, and then sintering it. As a result, the second portion 2b of the anode wire 2 is drawn out (extended) from one end face E1 of the anode body 1. In the anode wire 2, the second portion 2b is in contact with the anode lead frame 13 and electrically connected. The second portion 2b may be welded to the anode lead frame 13. The welding method is not particularly limited and examples include resistance welding and laser welding.

[0030] As explained above, the anode portion 6 has a dielectric layer 3. The dielectric layer 3 is formed on the surface of the anode body 1. The dielectric layer 3 is composed of, for example, a metal oxide. Methods for forming a layer containing a metal oxide on the surface of the anode body 1 include, for example, immersing the anode body 1 in a chemical solution to anodize the surface of the anode body 1, and heating the anode body 1 in an oxygen-containing atmosphere. The dielectric layer 3 is not limited to a layer containing a metal oxide as described above, and only needs to have insulating properties.

[0031] (Cathode section) The cathode section 7 has a solid electrolyte layer 4 formed on the dielectric layer 3 and a cathode layer 5 covering the solid electrolyte layer 4. The solid electrolyte layer 4 only needs to be formed to cover at least a part of the dielectric layer 3. In the example in Figure 1, the solid electrolyte layer 4 is formed to cover the entire surface of the dielectric layer 3. For example, manganese compounds and conductive polymers can be used for the solid electrolyte layer 4.

[0032] Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyparaphenylenevinylene, polyacene, polythiophenevinylene, polyfluorene, polyvinylcarbazole, polyvinylphenol, polypyridine, or derivatives of these polymers. These polymers may be used individually or in combination of two or more. The conductive polymer may also be a copolymer of two or more monomers. Considering its excellent conductivity, it is preferable to use polythiophene, polyaniline, or polypyrrole as the conductive polymer. Considering its excellent water repellency in addition to conductivity, it is preferable to use polypyrrole as the conductive polymer.

[0033] The solid electrolyte layer 4 containing the conductive polymer may be formed, for example, by polymerizing raw material monomers on the dielectric layer 3, or by coating the dielectric layer 3 with a liquid containing the conductive polymer. The solid electrolyte layer 4 may consist of one layer or two or more layers. If the solid electrolyte layer 4 consists of two or more layers, the composition of the conductive polymer contained in each layer may be different, and the method of forming each layer (e.g., polymerization method) may be different.

[0034] In this specification, polypyrrole, polythiophene, polyfuran, and polyaniline, etc., refer to polymers that have polypyrrole, polythiophene, polyfuran, and polyaniline, etc., as their basic skeletons. Therefore, polypyrrole, polythiophene, polyfuran, and polyaniline, etc., also include their respective derivatives. For example, polythiophene includes poly(3,4-ethylenedioxythiophene), etc.

[0035] Various known dopants may be added to the polymerization solution for forming a conductive polymer, or to the solution or dispersion of the conductive polymer, in order to improve the conductivity of the conductive polymer. The dopant is not particularly limited, and can be 1,5-naphthalenedisulfonic acid, 1,6-naphthalenedisulfonic acid, 1-octanesulfonic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, 2-methyl-5-isopropylbenzenesulfonic acid, 4-octylbenzenesulfonic acid, 4-nitrotoluene-2-sulfonic acid, m-nitrobenzenesulfonic acid, n-octylsulfonic acid, n-butanesulfonic acid, n-hexanesulfonic acid, o-nitrobenzenesulfonic acid, p-ethylbenzenesulfonic acid, trifluoromethanesulfonic acid, hydrooxybenzenesulfonic acid, butylnaphthalenesulfonic acid, benzenesulfonic acid, polystyrenesulfonic acid, polyvinylsulfonic acid, methanesulfonic acid, and derivatives thereof. Examples of derivatives include metal salts such as lithium salts, potassium salts, and sodium salts; ammonium salts such as methylammonium salts, dimethylammonium salts, and trimethylammonium salts; piperidium salts, pyrrolidium salts, and pyrrolinium salts.

[0036] When conductive polymers are dispersed in a dispersion medium in the form of particles, the average particle size D50 is, for example, 0.01 μm or more and 0.5 μm or less. Having an average particle size D50 within this range makes it easier for the conductive polymer particles to penetrate into the interior of the anode 1.

[0037] The cathode layer 5 includes, for example, a carbon layer 5a formed to cover the solid electrolyte layer 4, and a metal paste layer 5b formed on the surface of the carbon layer 5a. The carbon layer 5a includes, for example, a conductive carbon material such as graphite and a resin. The metal paste layer 5b includes, for example, metal particles such as silver and a resin. The configuration of the cathode layer 5 is not limited to the above, and any configuration that has a current collection function is acceptable.

[0038] <Cathode Lead Frame> The cathode lead frame 14 is electrically connected to the cathode portion 7. As shown in Figure 1, the cathode lead frame 14 is connected to the cathode layer 5 in the cathode portion 7, for example, via a conductive adhesive 8. The cathode lead frame 14 has a cathode lead embedded portion 141 which is embedded inside the outer casing 11 and electrically connected to the cathode portion 7, and a cathode lead exposed portion 142 which is exposed to the outside from one end face E3 of the outer casing 11.

[0039] As shown in Figure 1, the cathode lead embedded portion 141 has a first cathode lead portion 141a extending from one end face E3 of the outer casing 11 toward the capacitor element 10, a second cathode lead portion 141b extending downward from one end of the first cathode lead portion 141a (in the direction from the upper surface U toward the lower surface B), and a third cathode lead portion 141c extending from one end of the second cathode lead portion 141b along the lower surface B of the capacitor element 10.

[0040] As shown in Figure 2A, a first through-hole TH1 is formed in the second cathode lead portion 141b. Although Figure 2A shows an example in which the first through-hole TH1 has a rectangular shape, the shape of the first through-hole TH1 is not limited to a rectangular shape. The shape of the first through-hole TH1 may be circular, elliptical, or a polygonal shape other than a rectangle (for example, a hexagon or octagon).

[0041] As shown in Figure 1, in the solid electrolytic capacitor 100, the second cathode lead portion 141b is positioned to face the other end face E2 of the capacitor element 10 (the face opposite to the one end face E1 of the anode body 1), and the third cathode lead portion 141c is positioned to face the lower surface B of the capacitor element 10. Note that the first through hole TH1 is omitted from the illustration in Figure 1.

[0042] Furthermore, as shown in Figure 2B, the cathode lead frame 14 has a stepped shape before being connected to the cathode portion 7 of the capacitor element 10. Specifically, the cathode lead frame 14 has a second cathode lead portion 141b extending in the height direction HD, a third cathode lead portion 141c extending horizontally from the lower end of the second cathode lead portion 141b, a first cathode lead portion 141a extending in the opposite direction to the extension direction of the third cathode lead portion 141c from the upper end of the second cathode lead portion 141b, and a cathode lead exposed portion 142 connected to the first cathode lead portion 141a (the first cathode lead portion 141a and the cathode lead exposed portion 142 are collectively referred to as a connecting body 14A). After the third cathode lead portion 141c is connected to the cathode layer 5 via the conductive adhesive 8, the third cathode lead portion 141c, the second cathode lead portion 141b, and the first cathode lead portion 141a in the connecting body 14A are covered by the outer casing 11. Subsequently, the cathode lead exposed portion 142 in the connecting body 14A is bent to conform to one end face E3 and the lower surface of the outer casing 11, thereby providing the cathode lead frame 14 to the solid electrolytic capacitor 100.

[0043] In the solid electrolytic capacitor 100 according to an embodiment of the present disclosure, the direction connecting the upper surface U and the lower surface B of the capacitor element 10 is defined as the height direction HD, the length of the second cathode lead portion 141b in the height direction HD is defined as H1 (see FIG. 2A), and when the length of the portion in the height direction HD between the lowermost end of the first through hole TH1 in the second cathode lead portion 141b and the third cathode lead portion 141c is defined as D1 (see FIG. 2A), the relationship of D1 / H1 ≤ 0.19 is satisfied. Thereby, in the second cathode lead portion 141b, it is possible to suppress the moisture passing through the non-formed portion of the first through hole TH1 from entering the portion between the lowermost end of the first through hole TH1 and the third cathode lead portion 141c and then reaching the third cathode lead portion 141c (see FIG. 2A). That is, in the second cathode lead portion 141b, the moisture transmission path can be sufficiently narrowed. Therefore, the amount of moisture reaching the capacitor element 10 can be reduced. Note that the relationship of D1 / H1 ≤ 0.15 may be satisfied, the relationship of D1 / H1 ≤ 0.10 may be satisfied, the relationship of D1 / H1 ≤ 0.05 may be satisfied, or the relationship of D1 / H1 = 0 may be satisfied. Note that the relationship of D1 / H1 = 0 means that the lowermost end of the first through hole TH1 reaches the third cathode lead portion 141c.

[0044] When the length of the first through hole TH1 in the height direction HD is defined as H2, it is preferable that the relationship of H2 ≥ H1 / 5 is satisfied. Thereby, in the height direction HD, the first through hole TH1 can be opened with a sufficient length. Moisture that has entered from the outside of the exterior body 11 can be sufficiently discharged to the outside of the cathode lead frame 14 through the first through hole TH1. Note that the relationship of H2 ≥ H1 / 3 may be satisfied, the relationship of H2 ≥ H1 / 2 may be satisfied, or the relationship of H2 ≥ 2H1 / 3 may be satisfied. By satisfying such a relationship, in the height direction HD, the first through hole TH1 can be opened with a more sufficient length, so that moisture that has entered from the outside of the exterior body 11 can be more sufficiently discharged to the outside of the cathode lead frame 14. On the other hand, from the viewpoint of ensuring the mechanical strength of the second cathode lead portion 141b, it is preferable that the relationship of H2 ≤ 4H1 / 5 is satisfied.

[0045] In the capacitor element 10, when the direction connecting the sides is defined as the width direction WD, the length of the second cathode lead portion 141b in the width direction WD is defined as W1 (see FIG. 2A), and the length of the first through hole TH1 in the width direction WD is defined as W2 (see FIG. 2A), it is preferable to satisfy the relationship of W2 ≥ W1 / 2. By satisfying this relationship, in addition to being able to sufficiently narrow the moisture transmission path in the second cathode lead portion 141b, the first through hole TH1 can be opened with a sufficient length in the width direction WD. Note that the relationship of W2 ≥ 2W1 / 3 may also be satisfied. On the other hand, from the viewpoint of ensuring the mechanical strength of the second cathode lead portion 141b, it is preferable to satisfy the relationship of W2 ≤ 4W1 / 5.

[0046] The material for forming the cathode lead frame 14 is not particularly limited as long as it is electrochemically and chemically stable and has conductivity. The material for forming the cathode lead frame 14 may be, for example, a metal such as copper or a non-metal. As shown in FIG. 2B, when the cathode lead frame 14 has a stepped shape, this shape can be obtained by bending a flat conductor (conductor plate) or the like. From the viewpoint of reducing the height, the thickness of the conductor plate (the length between both main surfaces of the conductor plate) may be 25 μm or more and 200 μm or less, or may be 25 μm or more and 100 μm or less.

[0047] <Anode Lead Frame> As shown in FIG. 1, the anode lead frame 13 is electrically connected to the anode portion 6. The anode lead frame 13 has an anode lead embedded portion 131 embedded inside the exterior body 11 and an anode lead exposed portion​​As shown in Figures 3A and 3B, a second through-hole TH2 is formed in the anode lead portion 131a at a position that does not overlap with the anode wire 2 when viewed from the height direction HD. Note that the second through-hole TH2 is omitted from the illustration in Figure 1. Furthermore, the anode lead portion 131a refers to the portion of the anode lead embedded portion 131 that is demarcated by one end P facing the capacitor element 10 and the position furthest from this end P to the second through-hole TH2.

[0049] As shown in Figure 3A, a second through-hole TH2 may be formed in the anode lead portion 131a. This narrows the moisture transmission path in the anode lead embedded portion 131, thereby reducing the amount of moisture reaching the anode wire 2 from the anode lead embedded portion 131. The second through-hole TH2 may be formed to have a rectangular shape when viewed from the height direction HD. The second through-hole TH2 may be formed to include the center C of the anode lead embedded portion 131. As shown in Figure 3A, when the second through-hole TH2 is formed in a rectangular shape including the center C, the second portion 2b of the anode wire 2 may be welded to the anode lead portion 131a in the portion demarcated by one end P and the position closest to the second through-hole TH2 from this end P.

[0050] As shown in Figure 3B, it is preferable that the anode lead portion 131a has two second through holes TH2. Each of the two second through holes TH2 may be formed to have a circular shape when viewed from the height direction HD. It is preferable that each of the two second through holes TH2 is formed so as not to include the center C. In this case, the second portion 2b of the anode wire 2 will be welded to the anode lead portion 131a between the two second through holes TH2, thereby suppressing the occurrence of welding defects between the anode wire 2 and the anode lead portion 131a. This makes it possible to achieve high welding strength between the anode wire 2 and the anode lead portion 131a. It is preferable that the shortest distance between the anode wire 2 and the second through hole TH2 is 0.2 mm or more. This makes it possible to secure sufficient welding space between the anode wire 2 and the anode lead portion 131a, thereby sufficiently suppressing the occurrence of welding defects between the anode wire 2 and the anode lead portion 131a. The shortest distance mentioned above may be 0.3 mm or more, or 0.5 mm or more. The circular diameter of the second through-hole TH2 is preferably 0.1 mm or more. This allows the second through-hole TH2 to be opened to a sufficiently large size, thereby effectively suppressing moisture entering from outside the outer casing 11 and reaching the anode wire 2. The circular diameter of the second through-hole TH2 may be 0.2 mm or more, or 0.3 mm or more.

[0051] The configuration of the second through-hole TH2 is not limited to the examples shown in Figures 3A and 3B, and it may be formed in any configuration as long as it does not overlap with the anode wire 2. Furthermore, in the example shown in Figure 3A, the shape of the second through-hole TH2 is not limited to a rectangular shape, but may be circular, elliptical, or a polygonal shape other than a rectangle (for example, a hexagon or octagon). Furthermore, in the example shown in Figure 3B, the shape of the second through-hole TH2 is not limited to a circular shape, but may be elliptical, rectangular, or a polygonal shape other than a rectangle. Also, in the example shown in Figure 3B, the shapes of the two second through-holes TH2 may be different from each other. For example, one second through-hole TH2 may be circular, and the other second through-hole TH2 may have a shape other than a circle (for example, an elliptical or rectangular shape).

[0052] The anode lead frame 13 is typically a flat conductor (conductor plate) with a second through-hole TH2 formed therein before being connected to the anode portion 6 (more specifically, the anode wire 2) of the capacitor element 10. Such a flat anode lead frame 13 is fitted to the solid electrolytic capacitor 100 by welding a portion of it, including the second through-hole TH2, to the anode wire 2, covering this portion with the outer casing 11, and then bending the remaining portion, which does not include the second through-hole TH2, to follow the other end face E4 and the lower surface of the outer casing 11.

[0053] The material used to form the anode lead frame 13 is not particularly limited as long as it is electrochemically and chemically stable and electrically conductive. The material used to form the anode lead frame 13 may be a metal such as copper, or it may be a nonmetal. As described above, the anode lead frame 13 is usually a flat conductor (conducting plate) with a second through-hole TH2 formed therein before being connected to the anode portion 6 of the capacitor element 10. From the viewpoint of reducing the height, the thickness of the plate may be 25 μm or more and 200 μm or less, or 25 μm or more and 100 μm or less.

[0054] <Outer Covering> The outer covering 11 covers the capacitor element 10. The outer covering 11 is configured to cover the entire capacitor element 10. The outer covering 11 is provided to electrically insulate the anode lead frame 13 and the cathode lead frame 14, and is made of an insulating material (outer covering material). The outer covering 11 also protects the capacitor element 10 from impact and moisture. The outer covering material includes, for example, a thermosetting resin. Examples of thermosetting resins include epoxy resin, phenolic resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane resin, polyimide resin, and unsaturated polyester resin.

[0055] If the outer casing 11 is made of an outer casing material containing a thermosetting resin, an inorganic filler may be included in the outer casing 11. This can increase the strength of the outer casing 11. Examples of inorganic fillers that can be used include silicon dioxide (silica), aluminum oxide (alumina), zirconium oxide (zirconia), titanium oxide (titania), and magnesium oxide (magnesia).

[0056] The average particle size of inorganic fillers is, for example, between 60 μm and 80 μm. The average particle size of inorganic fillers can be determined in the same way as the average particle sizes of conductive and insulating particles.

[0057] [Method for Manufacturing a Solid Electrolytic Capacitor] A method for manufacturing a solid electrolytic capacitor according to one embodiment of the present disclosure, as shown in Figure 4, comprises the steps of: preparing a capacitor element (capacitor element preparation step (S1)); preparing an anode lead frame and a cathode lead frame (lead frame preparation step (S2)); electrically connecting the anode lead frame and the cathode lead frame to the capacitor element (connection step (S3)); and sealing the capacitor element, a part of the anode lead frame, and a part of the cathode lead frame (sealing step (S4)).

[0058] (1) Preparation process for capacitor element (S1) Valve metal particles and anode wire are placed in a mold and pressure-molded so that the first portion is embedded in the valve metal particles, and then the valve metal particles are sintered in a vacuum. This creates an anode portion in which the first portion of the anode wire is embedded inside the porous sintered body and the second portion of the anode wire is drawn out (extended) from one end face of the porous sintered body. In this anode portion, the porous sintered body corresponds to the anode body. The pressure for pressure molding is not particularly limited, for example, it is about 10 N to 100 N. A binder such as polyacrylic carbonate may be mixed with the valve metal particles as needed.

[0059] Next, a dielectric layer is formed on the porous sintered body (anode). Specifically, the porous sintered body (anode) is immersed in a chemical tank filled with an electrolytic aqueous solution (for example, an aqueous phosphoric acid solution), and the second part of the porous sintered body (anode) is connected to an anode provided in the chemical tank to perform anodic oxidation, thereby forming a dielectric layer consisting of an oxide film of a valve-acting metal on the surface of the porous sintered body (anode). The electrolytic aqueous solution is not limited to an aqueous phosphoric acid solution, but can also be nitric acid, acetic acid, sulfuric acid, etc.

[0060] Next, a solid electrolyte layer is formed on the dielectric layer. In one embodiment of this disclosure, an example of forming a solid electrolyte layer containing a conductive polymer is described. The solid electrolyte layer containing a conductive polymer can be formed, for example, by impregnating an anode body on which a dielectric layer is formed with at least one of a monomer and an oligomer, and then polymerizing at least one of the monomer and oligomer by chemical polymerization or electrolytic polymerization, or by impregnating an anode body on which a dielectric layer is formed with a solution or dispersion of a conductive polymer, and then drying it. The solid electrolyte layer is formed on at least a portion of the dielectric layer.

[0061] Next, a carbon layer is formed by applying carbon paste to the solid electrolyte and drying it, and then a metal paste layer is formed by applying metal paste to the carbon layer and drying it. This creates a cathode layer on the solid electrolyte layer, composed of the carbon layer and the metal paste layer. The configuration of the cathode layer is not limited to the above, and any configuration that has a current-collecting function is acceptable. A capacitor element is then fabricated.

[0062] (2) Preparation of lead frame (S2) (a) Preparation of anode lead frame The anode lead frame can be manufactured, for example, by forming a second through-hole at a predetermined location on a single flat conductor (conductor plate). The second through-hole is formed, for example, as shown in Figures 3A and 3B. Below, an example using an anode lead frame with two second through-holes formed as shown in Figure 3B will be described.

[0063] (b) Preparation process for the cathode lead frame The cathode lead frame can be manufactured, for example, by making a first through hole at a predetermined location on a flat conductor (conductor plate), and then bending the conductor plate with the first through hole into a stepped shape. The cathode lead frame is manufactured, for example, as shown in Figures 2A and 2B. The cathode lead frame has, for example, as shown in Figure 2B, a third cathode lead portion extending horizontally, a second cathode lead portion extending in the height direction from one end of the third cathode lead portion, and a connecting body between the first cathode lead portion and the cathode lead exposed portion, extending from one end of the second cathode lead portion in the opposite direction to the extension direction of the third cathode lead portion. In addition, as shown in Figure 2A, a first through hole is formed in the second cathode lead portion of the cathode lead frame. The following describes an example using the cathode lead frame shown in Figures 2A and 2B.

[0064] (3) Connection process (S3) First, a conductive adhesive is applied to a predetermined location on the lower surface of the capacitor element, and then the third cathode lead portion of the cathode lead frame is connected to the lower surface of the capacitor element via the conductive adhesive. This electrically connects the cathode lead frame to the capacitor element.

[0065] Next, the second portion of the anode wire is brought into contact with the anode lead frame so that it does not overlap with the second through-hole when viewed from the height direction of the capacitor element. Specifically, as shown in Figure 3B, the second portion of the anode wire is brought into contact with the anode lead frame so that it is located between the two second through-holes. Then, the second portion of the anode wire is welded to the anode lead frame. This electrically connects the anode lead frame to the capacitor element. Laser welding or resistance welding can be used for the welding described above. As a result, a capacitor element in which the anode lead frame and cathode lead frame are electrically connected can be obtained.

[0066] (4) Sealing process (S4) After placing the capacitor element and the outer casing material (for example, uncured thermosetting resin and inorganic filler) into the mold, the capacitor element is sealed by a transfer molding method or a compression molding method. At this time, a portion of the anode lead frame and the cathode lead frame is exposed from the mold. Specifically, the exposed portion of the anode lead and the exposed portion of the cathode lead are exposed from the mold. The molding conditions are not particularly limited, and the molding time and molding temperature can be set appropriately considering the thermosetting temperature of the thermosetting resin used.

[0067] As described above, an intermediate solid electrolytic capacitor can be obtained in which the entire capacitor element and a portion of the anode lead frame and cathode lead frame are covered by an outer casing. In the intermediate solid electrolytic capacitor obtained as described above, the cathode lead exposure portion extends from one end face of the outer casing, and the anode lead exposure portion extends from the other end face of the outer casing (the face opposite to the one end face).

[0068] Next, for the intermediate solid electrolytic capacitor product, the exposed cathode leads of the cathode lead frame are bent along one end face and the bottom surface of the casing, and the exposed anode leads of the anode lead frame are bent along the other end face and the bottom surface of the casing.

[0069] As described above, by performing the capacitor element preparation step (S1), the lead frame preparation step (S2), the connection step (S3), and the sealing step (S4), a solid electrolytic capacitor according to one embodiment of this disclosure (for example, a solid electrolytic capacitor as shown in Figure 1) can be manufactured.

[0070] In this specification, an example has been described in which the solid electrolytic capacitor 100 comprises one capacitor element 10, but the number of capacitor elements 10 in the solid electrolytic capacitor 100 may be multiple.

[0071] Furthermore, although this specification describes an example in which a second through-hole TH2 is formed in the anode lead portion 131a of the anode lead embedded portion 131, the anode lead portion 131a does not necessarily have to have a second through-hole TH2 formed therein.

[0072] (Note) The following technologies are disclosed as described above.

[0073] (Technology 1) A capacitor element having an anode portion and a cathode portion; a cathode lead frame electrically connected to the cathode portion; and an outer casing covering the capacitor element, wherein the capacitor element has a lower surface, an upper surface opposite to the lower surface, and two sides connecting the lower surface and the upper surface; the cathode lead frame has a cathode lead embedding portion embedded inside the outer casing and electrically connected to the cathode portion, and a cathode lead exposed portion exposed to the outside from a first end face of the outer casing, wherein the cathode lead embedding portion has a first cathode lead portion extending toward the capacitor element from the first end face of the outer casing, a second cathode lead portion extending downward from one end of the first cathode lead portion, and a third cathode lead portion extending along the lower surface of the capacitor element from one end of the second cathode lead portion, and the second cathode lead portion has a first through hole. A solid electrolytic capacitor that satisfies the relationship D1 / H1 ≤ 0.19, where H1 is the length of the second cathode lead portion in the height direction, and D1 is the length of the portion between the lowest end of the first through hole in the second cathode lead portion and the third cathode lead portion in the height direction.

[0074] (Technology 2) A solid electrolytic capacitor according to Technology 1, wherein when the length of the first through-hole in the height direction is H2, the relationship H2 ≥ H1 / 5 is satisfied.

[0075] (Technology 3) A solid electrolytic capacitor according to Technology 1 or 2, wherein when the direction connecting the two sides is defined as the width direction, the length of the second cathode lead portion in the width direction is W1, and the length of the first through hole in the width direction is W2, the relationship W2 ≥ W1 / 2 is satisfied.

[0076] (Technology 4) A solid electrolytic capacitor according to any one of Techniques 1 to 3, further comprising an anode lead frame electrically connected to the anode portion, wherein the anode portion comprises an anode body and an anode wire extending from one end face of the anode body, the anode lead frame comprises an anode lead embedding portion embedded inside the outer casing and an anode lead exposure portion exposed to the outside from a second end face opposite to the first end face of the outer casing, the anode lead embedding portion comprises an anode lead portion electrically connected to the anode wire, the anode lead portion and the anode wire are joined by welding, and the anode lead portion has a second through hole in a position that does not overlap with the anode wire when viewed from the height direction.

[0077] (Technical 5) The solid electrolytic capacitor according to Technical 4, wherein the anode lead portion has two second through holes, each of the two second through holes being the second through hole, and the anode wire is welded to the portion of the anode lead portion between the two second through holes.

[0078] (Technical 6) The solid electrolytic capacitor according to Technical 5, wherein the shortest distance between the anode wire and the second through hole is 0.2 mm or more.

[0079] (Technical 7) The solid electrolytic capacitor according to Technical 5 or 6, wherein the circular equivalent hole diameter of the second through hole is 0.1 mm or more.

[0080] The present disclosure will be described below in detail based on examples and comparative examples, but the present disclosure is not limited to the following examples.

[0081] [Example 1] <Capacitor element> (Anode part) Valve metal particles (Ta particles) and an anode wire were placed in a mold and pressure molded so that the first part was embedded in the valve metal particles, and then the valve metal particles were sintered in a vacuum. As a result, an anode part was produced in which the first part of the anode wire was embedded inside the porous sintered body, and the second part of the anode wire was drawn out (extended) from one end face of the porous sintered body. Polyacrylic carbonate was mixed with the valve metal particles as a binder. Furthermore, in the anode body produced as described above, the porous sintered body corresponds to the anode body.

[0082] (Dielectric layer) A porous sintered body (anode) is immersed in a chemical conversion tank filled with an aqueous phosphoric acid solution (phosphoric acid concentration of 0.010 mass%), and a second part of the porous sintered body (anode) is connected to the anode provided in the chemical conversion tank to perform anodizing, thereby forming an oxide film of valve metal (Ta) on the surface of the porous sintered body (anode). ２ O ５ A dielectric layer consisting of a coating was formed. Anodizing was carried out under the condition of applying a DC voltage of 70V for 20 minutes.

[0083] (Cathode section) An aqueous dispersion (conductive polymer solution) containing a polythiophene polymer was prepared as a self-doped conductive polymer. The concentration of the polythiophene polymer in the conductive polymer solution was 1 to 3% by mass. As the self-doped polythiophene polymer, PEDOT (weight-average molecular weight Mw: approximately 10,000), which has a sulfo group bonded to the PEDOT skeleton via a linking group containing a butylene group, was used.

[0084] An anode body with a dielectric layer formed on it (hereinafter referred to as a dielectric-layered anode body) was immersed in a conductive polymer solution for 30 to 60 seconds under atmospheric pressure (0.1 MPa (1 atm)), and then the dielectric-layered anode body was removed from the conductive polymer solution. Next, the anode body with the conductive polymer solution attached was heated (dried) at 140 to 180°C for 10 to 20 minutes to form a solid electrolyte layer containing a conductive polymer on the dielectric layer.

[0085] A dispersion of graphite particles in water was applied to a solid electrolyte layer, and then dried to form a carbon layer on the solid electrolyte. Drying was carried out at 130 to 180°C for 10 to 30 minutes. Next, a silver paste containing silver particles and a binder resin (epoxy resin) was applied to the carbon layer, and then the binder resin was heat-cured to form a silver paste layer on the carbon layer. The binder resin was heat-cured at 150 to 200°C for 10 to 60 minutes. This formed a cathode layer on the solid electrolyte layer consisting of the carbon layer and the silver paste layer. As a result, a cathode portion having a solid electrolyte layer and a cathode layer covering the solid electrolyte layer was fabricated, and a capacitor element according to Example 1 was obtained.

[0086] <Lead Frame> A flat conductor (conductor plate) was prepared as the anode lead frame. The cathode lead frame was prepared by first making a first through hole at a predetermined location on the flat conductor (conductor plate), and then bending the conductor plate with the first through hole into a stepped shape. Specifically, the cathode lead frame had a third cathode lead portion extending horizontally, a second cathode lead portion extending in the height direction from one end of the third cathode lead portion, and a connecting body between the first cathode lead portion and the cathode lead exposed portion, extending from one end of the second cathode lead portion in the opposite direction to the extension direction of the third cathode lead portion (see Figures 2A and 2B). The first through hole had a rectangular shape and was formed in the second cathode lead portion. The length H1 in the height direction HD of the second cathode lead portion was 0.53 mm, and the length W1 in the width direction WD was 2.4 mm. Furthermore, the length H2 in the height direction HD of the first through-hole was 0.3 mm, and the length W2 in the width direction WD was 1.2 mm. In addition, the length D1 in the height direction HD of the second cathode lead portion between the lowest end of the first through-hole and the third cathode lead portion was 0.1 mm. That is, D1 / H1 was 0.19. Also, H2 was 0.57 × H1 (≥ H1 / 5), and W2 was 0.5 × W1 (≥ W1 / 2).

[0087] <Solid Electrolytic Capacitor> After applying conductive adhesive to a predetermined location on the underside of the capacitor element, the third cathode lead portion of the cathode lead frame was connected to the underside of the capacitor element via the conductive adhesive. Next, the second portion of the anode wire was brought into contact with a predetermined location on the anode lead frame, and then the second portion of the anode wire was joined to the anode lead frame by resistance welding. This resulted in a capacitor element in which the anode lead frame and the cathode lead frame were electrically connected.

[0088] Next, the capacitor element and the casing material (uncured epoxy resin) were placed in a mold, and the capacitor element was sealed by compression molding. At this time, a portion of the anode lead frame and the cathode lead frame were exposed from the mold. Specifically, the exposed portion of the anode lead and the exposed portion of the cathode lead frame were exposed from the mold. In this way, an intermediate solid electrolytic capacitor was obtained. In the intermediate solid electrolytic capacitor, the exposed portion of the cathode lead extended from one end face of the casing, and the exposed portion of the anode lead extended from the other end face of the casing (the face opposite to the one end face).

[0089] Next, for the intermediate product of the solid electrolytic capacitor, the exposed cathode leads of the cathode lead frame were bent along one end face and the bottom surface of the casing, and further, the exposed anode leads of the anode lead frame were bent along the other end face and the bottom surface of the casing to produce the solid electrolytic capacitor according to Example 1.

[0090] [Example 2] A solid electrolytic capacitor according to Example 2 was manufactured in the same manner as in Example 1, except that the length W2 of the width direction WD of the first through hole in the second cathode lead portion of the cathode lead frame was set to 1.8 mm. That is, W2 was 0.75 × W1 (≧W1 / 2).

[0091] [Example 3] A solid electrolytic capacitor according to Example 3 was manufactured in the same manner as in Example 1, except that the length W2 of the width direction WD of the first through hole in the second cathode lead portion of the cathode lead frame was set to 2.0 mm. That is, W2 was 0.83 × W1 (≧W1 / 2).

[0092] [Comparative Example 1] A solid electrolytic capacitor according to Comparative Example 1 was manufactured in the same manner as in Example 1, except that the length W2 of the width direction WD of the first through hole in the second cathode lead portion of the cathode lead frame was set to 0.6 mm. That is, W2 was 0.25 × W1 (< W1 / 2).

[0093] ≪Evaluation≫ ・The solid electrolytic capacitors for each example were left for 64 hours and 88 hours in an environment with a hygroscopic temperature of 60°C and a relative humidity of 60% (60% RH). The increase in mass of each solid electrolytic capacitor after 64 hours and 88 hours was measured. The increase in mass of each solid electrolytic capacitor after 64 hours and 88 hours was calculated as the arithmetic mean of 138 test specimens.

[0094] The crack occurrence rate after reflow soldering was evaluated for each example of solid electrolytic capacitors that had been left for 64 hours in an environment of 60°C and 60% RH. The reflow soldering was performed using a temperature profile compliant with IPC / JEDEC J-STD-020. Specifically, the reflow soldering was performed by preheating from 150°C to 200°C, followed by main heating to a maximum temperature of 260°C. This main heating was repeated three times. The reflow soldering was performed by mounting each example of solid electrolytic capacitor onto a circuit board using lead-free solder. In Example 1, 197 solid electrolytic capacitors were mounted on the circuit board; in Example 2, 195 solid electrolytic capacitors were mounted; in Example 3, 134 solid electrolytic capacitors were mounted; and in Comparative Example 1, 206 solid electrolytic capacitors were mounted. The percentage of solid electrolytic capacitors mounted on the circuit boards that had cracks in their casings was calculated. The presence or absence of cracks was confirmed by a valve leak test.

[0095] The results of evaluating the hygroscopicity and crack occurrence rate of the solid electrolytic capacitors in each example are shown in Table 1 below.

[0096]

[0097] Table 1 shows that, at 64 hours and 88 hours, the hygroscopicity of the solid electrolytic capacitors in each embodiment is lower than that of the solid electrolytic capacitor in Comparative Example 1. Furthermore, it can be seen that as the length W2 of the width WD of the first through-hole increases, the hygroscopicity of the solid electrolytic capacitor decreases after 88 hours, and the crack occurrence rate also decreases.

[0098] Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

[0099] The solid electrolytic capacitor described herein can be used in applications where it is required to reduce the amount of moisture reaching the capacitor element from the outside of the casing.

[0100] 1: Anode body, 2: Anode wire, 2a: First part, 2b: Second part, 3: Dielectric layer, 4: Solid electrolyte layer, 5: Cathode layer, 5a: Carbon layer, 5b: Metal paste layer, 6: Anode part, 7: Cathode part, 8: Conductive adhesive, 10: Capacitor element, 11: Outer casing, 13: Anode lead frame, 14: Cathode lead frame, 14A: Connecting body, 100: Solid electrolytic capacitor, 131: Anode lead embedded part, 131a: Anode lead part, 132: Anode lead exposed part, 1 41: Cathode lead embedding section, 141a: First cathode lead section, 141b: Second cathode lead section, 141c: Third cathode lead section, B: Bottom surface, C: Center, D1, H1, H2: Length in the height direction, E1: One end face of the anode body, E2: Other end face of the capacitor element, E3: One end face of the casing (first end face), E4: Other end face of the casing (second end face), HD: Height direction, P: One end, TH1: First through hole, TH2: Second through hole, U: Top surface, W1, W2: Length in the width direction, WD: Width direction

Claims

1. A capacitor element having an anode portion and a cathode portion; a cathode lead frame electrically connected to the cathode portion; and an outer casing covering the capacitor element, wherein the capacitor element has a lower surface, an upper surface opposite to the lower surface, and two sides connecting the lower surface and the upper surface; the cathode lead frame has a cathode lead embedding portion embedded inside the outer casing and electrically connected to the cathode portion, and a cathode lead exposed portion exposed to the outside from a first end face of the outer casing; the cathode lead embedding portion has a first cathode lead portion extending from the first end face of the outer casing toward the capacitor element, a second cathode lead portion extending downward from one end of the first cathode lead portion, and a third cathode lead portion extending from one end of the second cathode lead portion along the lower surface of the capacitor element, the second cathode lead portion has a first through hole, and the direction connecting the upper surface and the lower surface of the capacitor element is the height direction. A solid electrolytic capacitor that satisfies the relationship D1 / H1 ≤ 0.19, where H1 is the length in the height direction of the second cathode lead portion, and D1 is the length in the height direction of the portion between the lowest end of the first through hole in the second cathode lead portion and the third cathode lead portion.

2. The solid electrolytic capacitor according to claim 1, wherein when the length of the first through-hole in the height direction is H2, the relationship H2 ≥ H1 / 5 is satisfied.

3. A solid electrolytic capacitor according to claim 1 or 2, wherein the direction connecting the two sides is defined as the width direction, the length of the second cathode lead portion in the width direction is W1, and the length of the first through hole in the width direction is W2, and the relationship W2 ≥ W1 / 2 is satisfied.

4. A solid electrolytic capacitor according to claim 1 or 2, further comprising an anode lead frame electrically connected to the anode portion, wherein the anode portion has an anode body and an anode wire extending from one end face of the anode body, the anode lead frame has an anode lead embedding portion embedded inside the outer casing and an anode lead exposed portion exposed to the outside from a second end face opposite to the first end face of the outer casing, the anode lead embedding portion has an anode lead portion electrically connected to the anode wire, the anode lead portion and the anode wire are joined by welding, and the anode lead portion has a second through hole in a position that does not overlap with the anode wire when viewed from the height direction.

5. The solid electrolytic capacitor according to claim 4, wherein the anode lead portion has two second through holes, each of the two second through holes being the second through hole, and the anode wire is welded to the portion of the anode lead portion between the two second through holes.

6. The minimum distance between the anode wire and the second through-hole is 0.2 mm or more, the solid electrolytic capacitor according to claim 5.

7. The solid electrolytic capacitor according to claim 5, wherein the circular diameter of the second through-hole is 0.1 mm or more.

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