Electrolytic capacitor

Abstract

To suppress an increase of an ESR.SOLUTION: An electrolytic capacitor to be disclosed, comprises: a capacitor element that has a positive electrode part and a negative electrode part; a positive electrode lead frame 30 that is electrically connected to the positive electrode part; a negative electrode lead frame 40 that is electrically connected to the negative electrode part; and an outer casing that covers a capacitor element. The positive electrode lead frame 30 has a positive electrode embedded part 31 that is embedded into the outer casing. The negative electrode lead frame 40 has a negative electrode embedded part 41 that is embedded into the outer casing. On at least one of the positive electrode embedded part 31 and the negative electrode embedded part 41, a plurality of concave parts 51 and a plurality of convex parts 52 positioned at an outer edge part of each concave part 51 are formed.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, electrolytic capacitors that use a metal oxide film as a dielectric are known (for example, Patent Document 1). The electrolytic capacitor of Patent Document 1 includes a capacitor element having an anode portion and a cathode portion, an anode lead frame electrically connected to the anode portion, a cathode lead frame electrically connected to the cathode portion, and an exterior body covering the capacitor element, where the anode lead frame has a first embedded portion embedded in the exterior body, and the cathode lead frame has a second embedded portion embedded in the exterior body, and a plurality of recesses are formed on the surface of at least one of the first embedded portion and the second embedded portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 008185 Summary of the Invention [Problem to be solved by the invention]

[0004] When an electrolytic capacitor is in use, oxygen or moisture may reach the capacitor element through the interface between the exterior body and each lead frame. If oxygen or moisture reaches the capacitor element, the electrolyte deteriorates and the equivalent series resistance (ESR) of the electrolytic capacitor increases. In such a situation, one of the objectives of the present disclosure is to suppress the increase in ESR. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to an electrolytic capacitor, the electrolytic capacitor comprising a capacitor element having an anode portion and a cathode portion, an anode lead frame electrically connected to the anode portion, a cathode lead frame electrically connected to the cathode portion, and an exterior body covering the capacitor element, the anode lead frame having an anode embedded portion embedded in the exterior body, the cathode lead frame having a cathode embedded portion embedded in the exterior body, and a plurality of recesses and a plurality of protrusions located on outer edges of each of the recesses are formed on at least one surface of the anode embedded portion and the cathode embedded portion. Effect of the Invention

[0006] According to the present disclosure, an increase in ESR can be suppressed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view illustrating a schematic diagram of an example of an electrolytic capacitor according to the present disclosure. [Diagram 2] FIG. 11 is a top view showing a schematic example of an arrangement of recesses and protrusions in each lead frame. [Diagram 3] 3 is a cross-sectional view showing a schematic cross section taken along line III-III in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of the electrolytic capacitor according to the present disclosure will be described below with reference to an example. However, the present disclosure is not limited to the example described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure can be obtained.

[0009] The electrolytic capacitor according to the present disclosure includes a capacitor element, an anode lead frame, a cathode lead frame, and an exterior body.

[0010] The capacitor element has an anode part and a cathode part. The anode part may be composed of an anode body, or may include an anode body and an anode wire. The anode body may be a porous sintered body, or may be a metal foil with a porous surface. A dielectric layer may be formed on the surface of the anode body. The cathode part may include an electrolyte layer (solid electrolyte layer) and a cathode layer. The electrolyte layer is disposed between the dielectric layer formed on the surface of the anode body and the cathode layer. There is no particular limitation on these components, and components used in known electrolytic capacitors may be applied. Examples of these components will be described below.

[0011] The anode body may be formed by sintering particles of the material. Examples of the particles of the material include particles of a valve metal, particles of an alloy containing a valve metal, and particles of a compound containing a valve metal. These particles may be used alone or in combination of two or more. Alternatively, a foil of a metal having valve action may be used as the anode body. Examples of the valve metal include titanium (Ti), tantalum (Ta), niobium (Nb), aluminum (Al), and the like. A preferred example of the anode body that is a sintered body is a tantalum sintered body. A preferred example of the anode body that is a metal foil is an aluminum foil.

[0012] The dielectric layer formed on the surface of the anode body is not particularly limited, and may be formed by a known method. For example, the dielectric layer may be formed by anodizing the surface of the anode body.

[0013] The anode wire may be made of a metal. Examples of the material of the anode wire include the valve metals mentioned above, copper, aluminum alloys, etc. A part of the anode wire is embedded in the anode body, and the remaining part protrudes from the end face of the anode body.

[0014] The electrolyte layer (solid electrolyte layer) is not particularly limited, and a solid electrolyte layer used in a known electrolytic capacitor may be applied. The electrolyte layer is disposed so as to cover at least a part of the dielectric layer. The electrolyte layer may be formed using a manganese compound or a conductive polymer. Examples of the conductive polymer include polypyrrole, polythiophene, polyaniline, and derivatives thereof. These may be used alone or in combination. The conductive polymer may be a copolymer of two or more monomers. The derivative of a conductive polymer means a polymer having a conductive polymer as a basic skeleton. For example, an example of a derivative of polythiophene includes poly(3,4-ethylenedioxythiophene).

[0015] It is preferable that a dopant is added to the conductive polymer. The dopant can be selected according to the conductive polymer, and a known dopant (e.g., a polymer dopant) may be used. Examples of the dopant include naphthalenesulfonic acid, p-toluenesulfonic acid, polystyrenesulfonic acid, and salts thereof. An example of the electrolyte layer is formed using poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrenesulfonic acid (PSS).

[0016] The electrolyte layer containing the conductive polymer may be formed by polymerizing a monomer as a raw material on the dielectric layer, or by depositing a liquid containing the conductive polymer (and optionally a dopant) on the dielectric layer and then drying the liquid.

[0017] The cathode layer is a layer having electrical conductivity and is disposed so as to cover at least a part of the electrolyte layer. The cathode layer includes a cathode extraction layer having electrical conductivity. The cathode layer may include another conductive layer (e.g., a carbon layer) disposed between the electrolyte layer and the cathode extraction layer. For example, the cathode layer may include a carbon layer formed on the electrolyte layer and a cathode extraction layer formed on the carbon layer. The cathode extraction layer may be formed of a metal paste (e.g., silver paste) containing metal particles (e.g., silver particles) and a resin, or may be formed of a known silver paste. The carbon layer is a layer containing carbon and may be formed of a conductive carbon material such as graphite and a resin.

[0018] The anode lead frame is electrically connected to the anode portion. The anode lead frame may have a base material made of a metal (copper, copper alloy, etc.). The thickness of the base material is not particularly limited and may be in the range of 25 μm or more and 200 μm or less (e.g., in the range of 25 μm or more and 100 μm or less). The anode lead frame may include a base material and a plating layer formed on the base material.

[0019] The plating layer is formed of a metal (including an alloy) such as nickel, gold, palladium, tin, or copper, and may include a nickel layer, a gold layer, a palladium layer, a tin layer, or a copper layer. For example, the plating layer may be laminated on the substrate in the order of a nickel layer, a gold layer, and a palladium layer. The plating layer may be formed by a known plating method. The plating layer may be formed before forming the recesses and protrusions described below, or may be formed after forming the recesses and protrusions.

[0020] The cathode lead frame is electrically connected to the cathode portion. It may have a base material made of a metal (copper, copper alloy, etc.). The thickness of the base material is not particularly limited and may be in the range of 25 μm or more and 200 μm or less (e.g., in the range of 25 μm or more and 100 μm or less). The cathode lead frame may include a base material and a plating layer formed on the base material. The plating layer of the cathode lead frame may be similar to the plating layer described above in relation to the anode lead frame.

[0021] The exterior body covers the capacitor element. The exterior body may be disposed around the capacitor element so that the capacitor element is not exposed on the surface of the electrolytic capacitor. Furthermore, the exterior body may be disposed so as to cover the anode-embedded portion and the cathode-embedded portion described below. The exterior body usually contains a resin (insulating resin) and an insulating filler.

[0022] The exterior body can be formed of a resin composition containing an insulating resin and an insulating filler (e.g., inorganic filler). The resin composition may contain a curing agent, a polymerization initiator, and / or a catalyst in addition to the insulating resin and the insulating filler. Examples of the insulating resin include an insulating thermosetting resin and an insulating thermoplastic resin. Specifically, examples of the insulating resin include an epoxy resin, a phenolic resin, a urea resin, a polyimide, a polyamideimide, a polyurethane, a diallyl phthalate, an unsaturated polyester, a polyphenylene sulfide (PPS), a polybutylene terephthalate (PBT), and the like.

[0023] Examples of the insulating filler include insulating particles, insulating fibers, etc. Examples of the insulating material constituting the insulating filler include insulating compounds (oxides, etc.) such as silica and alumina, glass, and mineral materials (talc, mica, clay, etc.). The insulating filler contained in the exterior body may be one type or two or more types.

[0024] The anode lead frame has an anode embedded portion embedded in the exterior body. The anode lead frame may be electrically connected to an anode portion of the capacitor element at the anode embedded portion, for example, by welding. The anode lead frame may further have an anode exposed portion exposed from the exterior body. At least a portion of the anode exposed portion may function as an anode external terminal.

[0025] The cathode lead frame has a cathode embedded portion embedded in the exterior body. The cathode lead frame may be electrically connected to the cathode portion of the capacitor element at the cathode embedded portion, for example, via a conductive adhesive layer. The conductive adhesive layer may contain conductive particles (e.g., metal particles such as silver particles). The conductive adhesive layer may be formed using a metal paste (e.g., silver paste) containing metal particles and a resin. The cathode lead frame may further have a cathode exposed portion exposed from the exterior body. At least a portion of the cathode exposed portion may function as a cathode external terminal.

[0026] At least one surface of the anode embedded portion and the cathode embedded portion has a plurality of recesses and a plurality of protrusions located at the outer edge of each recess. The surface of the anode embedded portion and / or the cathode embedded portion may be the main surface of the anode embedded portion and / or the cathode embedded portion. The recesses and protrusions may be formed by irradiating each embedded portion with a laser beam. The recesses and protrusions may be formed on both main surfaces of each embedded portion, or may be formed on only one main surface. By providing the recesses and protrusions, the surface area and anchor effect of the anode embedded portion and / or the cathode embedded portion are increased, and the adhesion between the anode embedded portion and / or the cathode embedded portion and the exterior body is improved. Therefore, oxygen and moisture are less likely to reach the capacitor element through the interface between each lead frame and the exterior body, and deterioration of the electrolyte layer can be suppressed, and thus an increase in ESR can be suppressed.

[0027] The protrusion may be formed in an annular shape along the outer edge of the recess. By providing such an annular protrusion, the surface area and anchor effect of the anode-embedded portion and / or the cathode-embedded portion can be effectively increased, and the increase in ESR can be further suppressed. The protrusion may be formed intermittently along the outer periphery of the recess.

[0028] Adjacent protrusions along the surface of the anode embedded part and / or cathode embedded part on which the recesses and protrusions are formed may be spaced apart from each other. In this configuration, an area where the surface of the anode embedded part and / or cathode embedded part is exposed is interposed between adjacent protrusions. Compared to the case where adjacent protrusions are connected to each other, the surface area of ​​each embedded part can be increased, and thus the reduction in ESR can be further suppressed.

[0029] The depth of the recess may be 10 μm or more and 55 μm or less. By setting the depth of the recess within this range, the adhesion between each lead frame and the exterior body or adhesive can be improved. The depth of the recess refers to the distance in the depth direction between the surface on which the recess is formed and the deepest part of the recess. The depth of the recess may be determined by measuring the depth of 10 arbitrarily selected recesses and averaging the measured values. The depth of the recess may be measured in a cross section parallel to the thickness direction of each lead frame.

[0030] The height of the convex portion may be 0.1 μm or more and 50 μm or less. By setting the height of the convex portion within this range, the adhesion between each lead frame and the exterior body or adhesive can be improved. The height of the convex portion refers to the height distance between the surface on which the convex portion is formed and the top of the convex portion. The height of the convex portion may be determined by measuring the height of 10 arbitrarily selected convex portions and averaging the measured values. The 10 arbitrarily selected convex portions may correspond to different concave portions. The height of the convex portion may be measured in a cross section parallel to the thickness direction of each lead frame.

[0031] The depth of the recesses may be 0.2 to 550 times the height of the protrusions. By setting the ratio between the depth of the recesses and the height of the protrusions within this range, the adhesion between each lead frame and the exterior body or adhesive can be improved.

[0032] When viewed from a direction perpendicular to the surface of the anode-embedded portion and / or the cathode-embedded portion, the ratio of the total area of ​​the plurality of recesses to the area of ​​the surface per unit area may be 5% or more and 25% or less. By setting the ratio of the total area of ​​the plurality of recesses to the area within this range, it is possible to improve the adhesion between each lead frame and the exterior body or adhesive. The total area of ​​the plurality of recesses per unit area may be found based on the area load ratio at the intersection of the load curve corresponding to the defined area of ​​the measurement surface (in this example, the surface of the anode-embedded portion and / or the cathode-embedded portion) and the height of the lower part of the core portion. The total area of ​​the plurality of recesses per unit area can be found using a laser microscope (for example, VK-X3000 manufactured by Keyence Corporation).

[0033] When viewed from a direction perpendicular to the surface of the anode-embedded portion and / or the cathode-embedded portion, the ratio of the total area of ​​the plurality of protrusions to the area of ​​the surface per unit area may be 5% or more and 30% or less. By setting the ratio of the total area of ​​the plurality of protrusions to the area within this range, it is possible to improve the adhesion between each lead frame and the exterior body or adhesive. The total area of ​​the plurality of protrusions per unit area may be found based on the area load ratio at the intersection of the load curve corresponding to the defined area of ​​the measurement surface (in this example, the surface of the anode-embedded portion and / or the cathode-embedded portion) and the height of the top of the core portion. The total area of ​​the plurality of protrusions per unit area can be found using a laser microscope (for example, VK-X3000 manufactured by Keyence Corporation).

[0034] When viewed from a direction perpendicular to the surface of the embedded anode portion and / or the embedded cathode portion, the total area of ​​the plurality of recesses per unit area may be 0.16 to 5 times the total area of ​​the plurality of protrusions. By setting the ratio between the total area of ​​the plurality of recesses and the total area of ​​the plurality of protrusions within this range, the adhesion between each lead frame and the exterior body or adhesive can be improved.

[0035] The average diameter of the opening of the recess may be 5 μm or more and 200 μm or less when viewed from a direction perpendicular to the surface of the anode embedded portion and / or the cathode embedded portion. By setting the average diameter of the opening of the recess within this range, the adhesion between each lead frame and the exterior body or adhesive can be improved. The diameter of the opening of the recess can be a circle equivalent diameter. The circle equivalent diameter can be obtained by the following method. First, the opening of the recess is photographed from above. Next, the area of ​​the opening is obtained by image processing the obtained image. Next, the circle equivalent diameter is calculated from the obtained area. The average diameter is obtained by calculating the diameter of the opening (circle equivalent diameter) for each of 10 arbitrarily selected recesses and arithmetically averaging the obtained diameters.

[0036] As described above, according to the present disclosure, by forming recesses and protrusions on the surface of a lead frame, an increase in the ESR of an electrolytic capacitor can be suppressed.

[0037] An example of an electrolytic capacitor according to the present disclosure will be specifically described below with reference to the drawings. The components described above can be applied to the components of the electrolytic capacitor of the example described below. The components of the electrolytic capacitor of the example described below can be modified based on the above description. The matters described below may also be applied to the above embodiment. Among the components of the electrolytic capacitor of the example described below, components that are not essential to the electrolytic capacitor of the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the shapes and numbers of actual members.

[0038] As shown in FIGS. 1 to 3, electrolytic capacitor 10 of this embodiment includes a capacitor element 20, an anode lead frame 30, a cathode lead frame 40, and an exterior body 60.

[0039] The capacitor element 20 has an anode portion 21, a dielectric layer 22, and a cathode portion 23. The anode portion 21 includes an anode body 21a and an anode wire 21b. The anode body 21a is a porous sintered body in a rectangular parallelepiped shape, and a dielectric layer 22 is formed on the surface.

[0040] A portion of anode wire 21b protrudes from one end face of anode body 21a toward one end face of electrolytic capacitor 10 (the left end face in FIG. 1). The other portion of anode wire 21b is embedded in anode body 21a. Anode wire 21b extends along the longitudinal direction of anode body 21a (the left-right direction in FIG. 1). Cathode portion 23 includes electrolyte layer 23a disposed so as to cover at least a portion of dielectric layer 22, and cathode layer 23b formed so as to cover at least a portion of electrolyte layer 23a.

[0041] The anode lead frame 30 is electrically connected to the anode portion 21. The anode lead frame 30 has an anode embedded portion 31 embedded in the exterior body 60 and an anode exposed portion 32 exposed from the exterior body 60. The anode embedded portion 31 is electrically connected to the anode portion 21 by welding. The anode exposed portion 32 includes an anode terminal portion 32a that functions as an anode side terminal.

[0042] Cathode lead frame 40 is electrically connected to cathode portion 23. Cathode lead frame 40 has a cathode embedded portion 41 embedded in exterior body 60 and a cathode exposed portion 42 exposed from exterior body 60. Cathode embedded portion 41 is electrically connected to cathode portion 23 via a conductive adhesive layer 43. Cathode exposed portion 42 includes a cathode terminal portion 42a that functions as a cathode side terminal.

[0043] Exterior body 60 covers capacitor element 20, anode embedded portion 31, and cathode embedded portion 41. The exterior body is disposed around capacitor element 20 so that capacitor element 20 is not exposed on the surface of electrolytic capacitor 10. Exterior body 60 contains an insulating resin and an insulating filler.

[0044] 2 and 3, a plurality of recesses 51 and a plurality of protrusions 52 located on the outer edge of the recesses 51 are formed on both surfaces (or both main surfaces) of each of the anode lead frame 30 and the cathode lead frame 40. Each protrusion 52 is preferably formed in an annular shape along the outer edge of the recess 51. Adjacent protrusions 52 along the surfaces are preferably spaced apart from each other.

[0045] The depth D of the recess 51 is preferably 20 μm or more and 30 μm or less. The height H of the protrusion 52 is preferably 0.1 μm or more and 1.0 μm or less. The depth D of the recess 51 is preferably 20 times or more and 300 times or less the height H of the protrusion 52.

[0046] When viewed from a direction perpendicular to the surfaces of the anode lead frame 30 and the cathode lead frame 40, the ratio of the total area of ​​the multiple recesses 51 to the area of ​​the surface per unit area is preferably 15% or more and 25% or less. When viewed from the same direction, the ratio of the total area of ​​the multiple protrusions 52 to the area of ​​the surface per unit area is preferably 5% or more and 15% or less. When viewed from the same direction, the total area of ​​the multiple recesses 51 per unit area is preferably 1.0 times or more and 3.0 times or less the total area of ​​the multiple protrusions 52. When viewed from the same direction, the average diameter of the openings of the recesses 51 is preferably 5 μm or more and 200 μm or less.

[0047] <Additional Notes> The above description of the embodiments discloses the following techniques. (Technology 1) a capacitor element having an anode portion and a cathode portion; an anode lead frame electrically connected to the anode portion; a cathode lead frame electrically connected to the cathode portion; an exterior body covering the capacitor element; Equipped with the anode lead frame has an anode embedded portion embedded in the exterior body, the cathode lead frame has a cathode embedded portion embedded in the exterior housing, At least one of the surfaces of the anode-embedded portion and the cathode-embedded portion has a plurality of recesses and protrusions located on outer edges of the recesses. (Technology 2) The electrolytic capacitor according to Technology 1, wherein the protrusion is formed in a ring shape along an outer edge of the recess. (Technology 3) The electrolytic capacitor according to claim 1 or 2, wherein adjacent protrusions along the surface are spaced apart from each other. (Technology 4) 4. The electrolytic capacitor according to any one of techniques 1 to 3, wherein the recess has a depth of 10 μm or more and 55 μm or less. (Technology 5) 5. The electrolytic capacitor according to any one of techniques 1 to 4, wherein the height of the protrusion is 0.1 μm or more and 50 μm or less. (Technology 6) 6. The electrolytic capacitor according to any one of Techniques 1 to 5, wherein the depth of the recess is 0.2 to 550 times the height of the protrusion. (Technology 7) The electrolytic capacitor according to any one of techniques 1 to 6, wherein the ratio of the total area of ​​the plurality of recesses to the area of ​​the surface per unit area when viewed from a direction perpendicular to the surface is 5% or more and 25% or less. (Technology 8) The electrolytic capacitor according to any one of techniques 1 to 7, wherein the ratio of the total area of ​​the plurality of protrusions to the area of ​​the surface per unit area when viewed from a direction perpendicular to the surface is 5% or more and 30% or less. (Technology 9) 9. The electrolytic capacitor according to any one of techniques 1 to 8, wherein the total area of ​​the plurality of recesses per unit area is 0.16 to 5 times the total area of ​​the plurality of protrusions when viewed from a direction perpendicular to the surface. (Technology 10) 10. The electrolytic capacitor according to any one of techniques 1 to 9, wherein an average diameter of an opening of the recess is 5 μm or more and 200 μm or less when viewed from a direction perpendicular to the surface. EXAMPLES

[0048] The electrolytic capacitors of Examples 1 to 3 and Comparative Examples 1 and 2 shown below were measured for the rate of change in ESR before and after a heat cycle test. The heat cycle test consisted of placing the electrolytic capacitors alternately in an atmosphere of -55°C and an atmosphere of 125°C for 15 minutes each, and repeating this cycle for approximately 1,000 cycles. The rate of change in ESR indicates how many times the ESR has increased before and after the heat cycle test. For example, a rate of change of 2 means that the ESR has doubled before and after the heat cycle test.

[0049] Example 1 An electrolytic capacitor corresponding to the above embodiment was prepared. The recesses and protrusions were formed by irradiating the surface of each lead frame with a laser beam. The depth of the recesses was 27.5 μm, and the height of the protrusions was 0.69 μm. The ratio of the total area of ​​the recesses to the surface area of ​​each lead frame per unit area was 20.7%, and the ratio of the total area of ​​the protrusions to the surface area of ​​each lead frame was 9.9%. The change rate of ESR before and after the heat cycle test was 1.2.

[0050] Example 2 An electrolytic capacitor corresponding to the above embodiment was prepared. The recesses and protrusions were formed by irradiating the surface of each lead frame with a laser beam. The depth of the recesses was 40.9 μm, and the height of the protrusions was 5.45 μm. The ratio of the total area of ​​the recesses to the surface area of ​​each lead frame per unit area was 7.6%, and the ratio of the total area of ​​the protrusions to the surface area of ​​each lead frame was 25.3%. The change rate of ESR before and after the heat cycle test was 1.5.

[0051] Example 3 An electrolytic capacitor corresponding to the above embodiment was prepared. The recesses and protrusions were formed by irradiating the surface of each lead frame with a laser beam. The depth of the recesses was 28.9 μm, and the height of the protrusions was 2.66 μm. The ratio of the total area of ​​the recesses to the surface area of ​​each lead frame per unit area was 15.6%, and the ratio of the total area of ​​the protrusions to the surface area of ​​each lead frame was 16.7%. The change rate of ESR before and after the heat cycle test was 1.3.

[0052] Comparative Example 1 An electrolytic capacitor was prepared in which each lead frame had a concave portion but no convex portion. The concave portion was formed by cutting the surface of each lead frame. The depth of the concave portion was 27.5 μm. The ratio of the total area of ​​the multiple concave portions to the surface area of ​​each lead frame per unit area was 20.7%. The rate of change in ESR before and after the heat cycle test was 5.

[0053] Comparative Example 2 An electrolytic capacitor with neither a concave nor a convex portion on each lead frame was prepared. The change in ESR before and after the heat cycle test was 10.

[0054] As described above, the electrolytic capacitors of Examples 1 to 3 had a lower rate of change in ESR before and after the heat cycle test compared to the electrolytic capacitors of Comparative Examples 1 and 2. Therefore, it can be said that the superiority of each Example was demonstrated. [Industrial Applicability]

[0055] The present disclosure can be used for electrolytic capacitors. [Explanation of symbols]

[0056] 10: Electrolytic capacitor 20: Capacitor element 21: Anode part 21a: Anode body 21b: Anode wire 22: Dielectric layer 23: Cathode 23a: Electrolyte layer 23b: Cathode layer 30: Anode lead frame 31: Anode buried part 32:Anode exposed part 32a:Anode terminal part 40: Cathode lead frame 41: Cathode buried part 42: Cathode exposed part 42a: Cathode terminal part 43: Conductive adhesive layer 51: Recess 52: Convex 60: Exterior body D: Depth of the recess H: Height of the protrusion

Claims

1. a capacitor element having an anode portion and a cathode portion; an anode lead frame electrically connected to the anode portion; a cathode lead frame electrically connected to the cathode portion; an exterior body covering the capacitor element; Equipped with the anode lead frame has an anode embedded portion embedded in the exterior body, the cathode lead frame has a cathode embedded portion embedded in the exterior housing, an electrolytic capacitor, wherein a plurality of recesses and a plurality of protrusions located on outer edges of each of the recesses are formed on a surface of at least one of the anode-embedded portion and the cathode-embedded portion;

2. The electrolytic capacitor according to claim 1 , wherein the protrusion is formed in an annular shape along an outer edge of the recess.

3. The electrolytic capacitor according to claim 1 , wherein adjacent protrusions along the surface are spaced apart from each other.

4. 3. The electrolytic capacitor according to claim 1, wherein the depth of the recess is not less than 10 μm and not more than 55 μm.

5. 3. The electrolytic capacitor according to claim 1, wherein the height of the protrusion is 0.1 μm or more and 50 μm or less.

6. 3. The electrolytic capacitor according to claim 1, wherein the depth of the recess is 0.2 to 550 times the height of the protrusion.

7. 3. The electrolytic capacitor according to claim 1, wherein a ratio of a total area of ​​the plurality of recesses to an area of ​​the surface per unit area when viewed in a direction perpendicular to the surface is 5% or more and 25% or less.

8. 3. The electrolytic capacitor according to claim 1, wherein a ratio of a total area of ​​the plurality of protrusions to an area of ​​the surface per unit area when viewed in a direction perpendicular to the surface is 5% or more and 30% or less.

9. 3. The electrolytic capacitor according to claim 1, wherein a total area of ​​the plurality of recesses per unit area is 0.16 to 5 times a total area of ​​the plurality of protrusions when viewed from a direction perpendicular to the surface.

10. 3. The electrolytic capacitor according to claim 1, wherein an average diameter of the opening of the recess is 5 μm or more and 200 μm or less when viewed in a direction perpendicular to the surface.

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