Solid electrolytic capacitor manufacturing method and solid electrolytic capacitor

Abstract

A solid electrolytic capacitor manufacturing method according to the present invention comprises the following steps. (A) A step for preparing a first sheet 10. The first sheet 10 comprises: a valve metal substrate 11 having a porous section 12 on a surface thereof; a dielectric layer formed on the surface of the porous section 12; and a solid electrolyte layer 13 provided on the dielectric layer. The first sheet 10 further has a plurality of element regions R11, R12. Each of the element regions R11, R12 is defined by a first end section E11 and a second end section E12 facing each other in the length direction and a first side section S11 and a second side section S12 facing each other in the width direction. In the first sheet 10, a first through-hole H1 having a width equal to or larger than the width of each of the element regions R11, R12 is formed so as to extend across the first end section E11 of each of the element regions R11, R12, and one or more second through-holes H2 having a width smaller than the width of each of the element regions R11, R12 are formed so as to extend across the second end section E12 of each of the element regions R11, R12. (B) A step for preparing a second sheet 20. The second sheet 20 is composed of a metal foil. The second sheet 20 further has a plurality of element regions R21, R22. Each of the element regions R21, R22 is defined by a first end section E21 and a second end section E22 facing each other in the length direction, and a first side section S21 and a second side section S22 facing each other in the width direction. In the second sheet 20, one or more third through-holes H3 having a width smaller than the width of each of the element regions R21, R22 are formed so as to extend across the first end section E21 of each of the element regions R21, R22, and a fourth through-hole H4 having a width equal to or larger than the width of each of the element regions R21, R22 is formed so as to extend across the second end section E22 of each of the element regions R21, R22. (C) A step for fabricating a laminated sheet 30. In the step (C), the first sheet 10 and the second sheet 20 are laminated so that the first end sections E11, E21 of the respective element regions R11, R12, R21, R22 face each other and the second end sections E12, E22 thereof face each other. In the laminated sheet 30, the first through-holes H1 and the third through-holes H3, and the second through-holes H2 and the fourth through-holes H4 communicate with each other in the lamination direction. (D) A step for fabricating a laminated block body 40, as needed. In the step (D), the first through-holes H1 and the third through-holes H3, and the second through-holes H2 and the fourth through-holes H4 are respectively filled with a sealing material from at least one principal surface side of a first principal surface M31 and a second principal surface M32 facing each other in the lamination direction of the laminated sheet 30. (E) A step for fabricating a plurality of element laminates 100 by cutting the laminated sheet 30 or the laminated block body 40. (F) A step for forming a first external electrode 141 and a second external electrode 142 on each of the element laminates 100. The step (A) for preparing the first sheet 10 includes a step for forming the first through-holes H1 and the second through-holes H2 in the first sheet 10. The step (B) for preparing the second sheet 20 includes a step for forming the third through-holes H3 and the fourth through-holes H4 in the second sheet 20. In at least one of the step (A) for preparing the first sheet 10 and the step (B) for preparing the second sheet 20, at least one of the first through-holes H1, the second through-holes H2, the third through-holes H3, and the fourth through-holes H4 is formed by laser processing. In the laser processing, the sheet is cut while the periphery of a laser-irradiated section is oxidized by irradiating the sheet with a laser beam.

Description

Method for manufacturing solid electrolytic capacitor and solid electrolytic capacitor

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

[0002] Patent Document 1 describes a method for manufacturing a solid electrolytic capacitor and a solid electrolytic capacitor. The method for manufacturing a solid electrolytic capacitor described in Patent Document 1 includes: (A) a step of preparing a first sheet, (B) a step of preparing a second sheet, (C) a step of coating the first sheet with an insulating material, (D) a step of forming a conductor layer on the first sheet, (E) a step of producing a laminated sheet, (F) a step of producing a laminated block body, (G) a step of producing a plurality of element laminate bodies by cutting the laminated block body, and (H) a step of forming a first external electrode and a second external electrode.

[0003] Japanese Unexamined Patent Application Publication No. 2019-79866

[0004] Patent Document 1 describes that through holes are formed by punching or the like in a valve action metal substrate having a dielectric layer formed on its surface and a first sheet provided with a solid electrolyte layer on the dielectric layer, and a second sheet made of a metal foil, respectively, in order to distinguish the polarities of the positive and negative electrodes. However, when through holes are formed by machining such as punching, the metal in the machined portion may dissolve and corrode due to the environment, and the dissolved metal components may precipitate near the capacitor element, resulting in a short circuit and malfunction. This is because a passive film is not formed in machining such as punching, and the corrosion resistance depends only on the natural oxide film of metals such as aluminum.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a method for manufacturing a solid electrolytic capacitor capable of manufacturing a solid electrolytic capacitor having excellent corrosion resistance. Another object of the present invention is to provide a solid electrolytic capacitor having excellent corrosion resistance.

[0006] The method for manufacturing a solid electrolytic capacitor of the present invention comprises the following steps: (A) Step of preparing a first sheet; The first sheet comprises a valve-acting metal substrate having a porous portion on its surface, a dielectric layer formed on the surface of the porous portion, and a solid electrolyte layer provided on the dielectric layer; Furthermore, the first sheet has a plurality of element regions, each element region is partitioned by a first end and a second end opposite to each other in the length direction, and a first side and a second side opposite to each other in the width direction; Furthermore, the first sheet has a first through hole formed so as to straddle the first end of each element region and having a width greater than or equal to the width of the element region, and one or more second through holes formed so as to straddle the second end of each element region and having a width less than the width of the element region; (B) Step of preparing a second sheet; The second sheet is made of metal foil; Furthermore, the second sheet has a plurality of element regions, each element region is demarcated by a first end and a second end facing each other in the length direction, and a first side and a second side facing each other in the width direction, and furthermore, the second sheet has one or more third through holes formed thereon that straddle the first end of each element region and have a width smaller than the width of the element region, and a fourth through hole formed thereon that straddles the second end of each element region and has a width greater than or equal to the width of the element region, (C) Step of manufacturing a laminated sheet; (C) Step is to laminate the first sheet and the second sheet so that the first ends and second ends of each element region face each other, and furthermore, in the laminated sheet, the first through hole and the third through hole, and the second through hole and the fourth through hole are in communication in the lamination direction, (D) Step of manufacturing a laminated block body as necessary; (D) In ​​step (D), a sealing material is filled into the first through hole and the third through hole, and the second through hole and the fourth through hole, respectively, from at least one of the first and second main surfaces of the laminated sheet that are opposite each other in the lamination direction; (E) A step of manufacturing a plurality of element laminates by cutting the laminated sheet or the laminated block;(F) A step of forming a first external electrode and a second external electrode on the element laminate; (A) A step of preparing a first sheet, comprising the step of forming a first through hole and a second through hole in the first sheet; (B) A step of preparing a second sheet, comprising the step of forming a third through hole and a fourth through hole in the second sheet; (A) A step of preparing a first sheet and (B) A step of preparing a second sheet, comprising forming at least one of the first through hole, the second through hole, the third through hole and the fourth through hole by laser processing; In the laser processing, the sheet is cut while irradiating it with a laser and oxidizing the area around the laser irradiation part.

[0007] The present invention relates to a solid electrolytic capacitor comprising an element stack, a first external electrode, and a second external electrode, wherein the element stack comprises a first layer and a second layer, the first layer comprises a valve-acting metal substrate having a porous portion on its surface, a dielectric layer formed on the surface of the porous portion, and a solid electrolyte layer provided on the dielectric layer, the second layer is made of metal foil, further comprising the element stack having a first end face and a second end face opposite each other in the longitudinal direction, the metal foil and the first sealing portion exposed on the first end face, the valve-acting metal substrate and the second sealing portion exposed on the second end face, the first external electrode is provided on the first end face of the element stack and connected to the metal foil, and the second external electrode is provided on the second end face of the element stack and connected to the valve-acting metal substrate. The valve-acting metal substrate has a third end face located on the first end face side and covered by the first sealing portion, and a fourth end face located on the second end face side and facing the second sealing portion, and the metal foil has a fifth end face located on the first end face side and facing the first sealing portion, and a sixth end face located on the second end face side and covered by the second sealing portion, and an oxide film is formed on at least one of the third end face, the fourth end face, the fifth end face and the sixth end face.

[0008] According to the present invention, it is possible to manufacture solid electrolytic capacitors with excellent corrosion resistance. Furthermore, according to the present invention, it is possible to provide solid electrolytic capacitors with excellent corrosion resistance.

[0009] Figure 1A is a schematic perspective view showing an example of a first sheet, and Figure 1B is a perspective view showing an enlarged portion of Figure 1A. Figure 2A is a schematic perspective view showing an example of a second sheet, and Figure 2B is a perspective view showing an enlarged portion of Figure 2A. Figure 3A is a schematic perspective view showing an example of the state before the first and second sheets are laminated, and Figure 3B is a perspective view showing an example of a laminated sheet. Figure 4A is a schematic perspective view showing an example of a laminated block, and Figure 4B is a perspective view showing an enlarged, exploded portion of Figure 4A. Figure 5A is a schematic plan view showing a valve-acting metal substrate before cutting, and Figure 5B is a schematic plan view showing a valve-acting metal substrate after cutting. Figure 6A is a schematic plan view showing a metal foil before cutting, and Figure 6B is a schematic plan view showing a metal foil after cutting. Figure 7 is a schematic cross-sectional view showing an example of an element laminate. Figures 8A and 8B are schematic perspective views showing an example of an element stack. Figure 9A is a schematic perspective view showing an example of a stacked block after cutting, and Figure 9B is a perspective view showing a part of Figure 9A disassembled and enlarged. Figure 10A is a schematic perspective view showing an example of a stacked block with a fourth sealing portion formed thereon, and Figure 10B is a perspective view showing a part of Figure 10A disassembled and enlarged. Figure 11A is a schematic perspective view showing an example of a fragmented element stack, and Figure 11B is a perspective view showing a part of Figure 11A disassembled and enlarged. Figure 12 is a schematic cross-sectional view showing an example of a solid electrolytic capacitor. Figures 13A and 13B are schematic perspective views showing an example of a solid electrolytic capacitor according to the first embodiment of the present invention. Figure 14 is a schematic diagram showing an example of a cross-section passing through the valve-acting metal substrate of the element stack shown in Figures 13A and 13B. Figure 15 is a schematic diagram showing an example of a cross-section passing through the metal foil of the element stack shown in Figures 13A and 13B. Figure 16A is a schematic perspective view showing another example of a stacked block after cutting, and Figure 16B is a perspective view showing an enlarged and disassembled part of Figure 16A. Figures 17A and 17B are schematic perspective views showing an example of a solid electrolytic capacitor according to a second embodiment of the present invention. Figure 18 is a schematic diagram showing an example of a cross-section passing through the valve-acting metal substrate of the element stack shown in Figures 17A and 17B. Figure 19 is a schematic diagram showing an example of a cross-section passing through the metal foil of the element stack shown in Figures 17A and 17B.Figures 20A and 20B are schematic perspective views showing an example of a solid electrolytic capacitor according to a third embodiment of the present invention. Figure 21 is a schematic diagram showing an example of a cross-section passing through the valve-acting metal substrate of the element laminate shown in Figures 20A and 20B. Figure 22 is a schematic diagram showing an example of a cross-section passing through the metal foil of the element laminate shown in Figures 20A and 20B. Figure 23 is a schematic perspective view showing an example of a laminated sheet after cutting. Figure 24 is a schematic perspective view showing an example of the structure of a resin substrate. Figure 25A is a schematic perspective view showing an example of a structure in which strip-shaped laminated sheets are arranged on a resin substrate, and Figure 25B is a cross-sectional view taken along line A-A in Figure 25A. Figure 26 is a schematic cross-sectional view showing an example of a state in which strip-shaped laminated sheets are sealed. Figure 27A is a schematic perspective view showing an example of a state in which strip-shaped laminated sheets are sealed with insulating resin, and Figure 27B is a schematic perspective view showing an example of a state in which the laminated sheets are separated into individual pieces. Figure 28 is a schematic plan view of the aluminum plate used for observation and compositional analysis by SEM-EDX.

[0010] The method for manufacturing a solid electrolytic capacitor and the solid electrolytic capacitor of the present invention will be described below. However, the present invention is not limited to the following configurations and can be modified and applied as appropriate without changing the gist of the invention. Furthermore, a combination of two or more of the individual desirable configurations of the present invention described below also constitutes the present invention.

[0011] The embodiments described below are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. In the second and subsequent embodiments, descriptions of matters common to the first embodiment will be omitted, and only the differences will be explained. In particular, similar effects and advantages due to similar configurations will not be mentioned sequentially for each embodiment.

[0012] (First Embodiment) [Method for Manufacturing a Solid Electrolytic Capacitor] An example of a method for manufacturing a solid electrolytic capacitor according to the first embodiment of the present invention will be described step by step below.

[0013] (A) Steps for preparing the first sheet First, the first sheet is prepared. The first sheet comprises a valve-acting metal substrate having a porous portion on its surface, a dielectric layer formed on the surface of the porous portion, and a solid electrolyte layer provided on the dielectric layer. Furthermore, the first sheet has a plurality of element regions. In the first sheet, each element region is demarcated by a first end and a second end that are opposite in the length direction, and a first side and a second side that are opposite in the width direction perpendicular to the length direction. Furthermore, the first sheet has a first through hole formed so as to straddle the first end of each element region and having a width greater than or equal to the width of the element region, and one or more second through holes formed so as to straddle the second end of each element region and having a width less than the width of the element region.

[0014] Figure 1A is a schematic perspective view showing an example of the first sheet, and Figure 1B is a perspective view that is an enlarged portion of Figure 1A. The first sheet 10 shown in Figures 1A and 1B has a plurality of element regions R11 (hereinafter referred to as the first element region) and a plurality of element regions R12 (hereinafter referred to as the second element region).

[0015] As shown in Figure 1B, the first element region R11 is divided by a first end E11 and a second end E12 that are opposite each other in the length direction (L direction), and a first side S11 and a second side S12 that are opposite each other in the width direction (W direction) perpendicular to the length direction. The dimension of the first element region R11 in the length direction (L direction) is greater than the dimension in the width direction (W direction). One first through hole H1 is formed so as to straddle the first end E11 of the first element region R11 in the length direction, and a plurality of second through holes H2 (three in Figure 1B) are formed so as to straddle the second end E12 of the first element region R11 in the length direction. The first through hole H1 consists of one elongated hole with a width greater than or equal to the width of the first element region R11, and the second through holes H2 consist of a plurality of substantially round holes with a width less than the width of the first element region R11.

[0016] On the other hand, the second element region R12 has the same shape as the first element region R11, but the orientation of the first end E11 and the second end E12 is opposite to that of the first element region R11.

[0017] As shown in Figure 1A, in the first sheet 10, first element regions R11 and second element regions R12 are arranged alternately in the longitudinal direction. As shown in Figure 1B, the first element region R11 shares a first end E11 and a first through hole H1 with an adjacent second element region R12, and shares a second end E12 and a second through hole H2 with another adjacent second element region R12.

[0018] Furthermore, as shown in Figure 1A, in the first sheet 10, the first element region R11 and the second element region R12 are arranged alternately in the width direction. As shown in Figure 1B, the first element region R11 shares a first side portion S11 with an adjacent second element region R12, and also shares a second side portion S12 with another adjacent second element region R12.

[0019] As shown in Figure 1B, the first sheet 10 comprises a valve-acting metal substrate 11 having a porous portion 12 on its surface, a dielectric layer (not shown) formed on the surface of the porous portion 12, and solid electrolyte layers 13 provided inside each element region on the dielectric layer. In the first sheet 10, the ends and sides of each element region may be covered with a mask layer 14 made of an insulating material, and the solid electrolyte layer 13 may be provided in the region surrounded by the mask layer 14.

[0020] In the first sheet 10 shown in Figure 1B, the valve-acting metal substrate 11 has porous portions 12 on both sides, with a dielectric layer formed on the surface of each porous portion 12, and a solid electrolyte layer 13 provided on the dielectric layer. However, if the second sheet is not laminated on one side of the first sheet, a solid electrolyte layer does not need to be provided on the surface of the valve-acting metal substrate on the side where the second sheet (metal foil) is not laminated. In this case, a dielectric layer may not be formed on the surface of the valve-acting metal substrate on the side where the second sheet (metal foil) is not laminated, nor may a porous portion be formed. Alternatively, the first sheet 10 may be one in which the valve-acting metal substrate 11 has a porous portion 12 on only one side, with a dielectric layer formed on the surface of the porous portion 12.

[0021] The first sheet is preferably manufactured as follows. First, a valve-acting metal substrate 11 having a porous portion 12 on its surface is prepared, and a dielectric layer is formed on the surface of the porous portion 12. For example, when aluminum foil is used as the valve-acting metal substrate, a dielectric layer consisting of an oxide film can be formed by performing an anodic oxidation treatment (also called a chemical conversion treatment) on the surface of the aluminum foil in an aqueous solution containing ammonium adipate or the like.

[0022] The valve-acting metal substrate consists of a valve-acting metal that exhibits so-called valve action. Examples of valve-acting metals include elemental metals such as aluminum, tantalum, niobium, titanium, and zirconium, or alloys containing these metals. Among these, aluminum or aluminum alloys are preferred.

[0023] The shape of the valve metal substrate is preferably flat, and more preferably foil-shaped. The porous portion can be formed by etching the surface of the valve metal substrate, or by printing valve metal powder of the same or different type as the valve metal substrate onto the surface of the valve metal substrate and sintering as necessary. When the valve metal is aluminum or an aluminum alloy, it is preferable to form the porous portion by etching, and when the valve metal is any other, it is preferable to form the porous portion by printing valve metal powder and sintering as necessary.

[0024] The thickness of the valve-acting metal substrate is not particularly limited, but the thickness of the portion excluding the porous part is preferably 5 μm or more and 100 μm or less. Furthermore, the thickness of the porous part (thickness on one side) is preferably 5 μm or more and 200 μm or less.

[0025] The dielectric layer formed on the surface of the porous portion is porous, reflecting the surface state of the porous portion, and has a fine, uneven surface shape. Preferably, the dielectric layer is made of an oxide film of the valve-acting metal.

[0026] Furthermore, from the viewpoint of improving manufacturing efficiency, a chemical conversion foil that has been pre-treated with chemical conversion may be used as the valve-acting metal substrate on which the dielectric layer is formed on the surface.

[0027] Next, a mask layer 14 may be formed to cover the edges and sides of each element region.

[0028] The mask layer is formed, for example, by applying a mask material made of an insulating material such as an insulating resin to the surface of the valve-acting metal substrate and solidifying or hardening it by heating or the like. The mask material is preferably applied by screen printing, dispenser application, inkjet printing, or the like.

[0029] Examples of insulating materials for masks include polyphenylsulfone resins, polyethersulfone resins, cyanate ester resins, fluororesins (tetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, etc.), compositions consisting of soluble polyimidesiloxane and epoxy resin, polyimide resins, polyamideimide resins, and insulating resins such as derivatives or precursors thereof.

[0030] Next, a solid electrolyte layer 13 is formed inside each element region on the dielectric layer. In this case, the solid electrolyte layer 13 may be formed in the region surrounded by the mask layer 14. For example, a solid electrolyte layer can be formed in a predetermined region by applying the following processing liquid or dispersion onto the dielectric layer by sponge transfer, screen printing, dispenser, inkjet printing, etc.

[0031] The solid electrolyte layer is formed, for example, by using a treatment solution containing a monomer such as 3,4-ethylenedioxythiophene to form a polymerized film such as poly(3,4-ethylenedioxythiophene) on the surface of the dielectric layer, or by applying a dispersion of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric layer and drying it. It is preferable to form the solid electrolyte layer by first forming an inner layer that fills the pores (recesses) of the dielectric layer, and then forming an outer layer that covers the dielectric layer.

[0032] Examples of materials constituting the solid electrolyte layer include conductive polymers such as polypyrroles, polythiophenes, and polyanilines. Among these, polythiophenes are preferred, and poly(3,4-ethylenedioxythiophene) called PEDOT is particularly preferred. Furthermore, the conductive polymer may contain dopants such as polystyrene sulfonic acid (PSS).

[0033] Subsequently, a first through-hole H1 is formed so as to straddle the first end E11 of each element region, and a second through-hole H2 is formed so as to straddle the second end E12 of each element region.

[0034] The first and second through holes are formed by laser processing, in which the first sheet is cut while irradiating it with a laser and oxidizing the area around the laser-irradiated part. This allows a passivation film to be formed on the processed portion, which is thicker than the native oxide film. Therefore, the corrosion resistance of the first and second through holes is improved, and the corrosion resistance of the solid electrolytic capacitor is also improved.

[0035] Here, for example, an IR laser, a UV laser, etc., can be used as the laser. The pulse width of the laser is preferably attosecond or longer and millisecond or shorter, and more preferably femtosecond or longer and nanosecond or shorter. The frequency of the laser is preferably 10 kHz or longer and 10 MHz or shorter, and more preferably 100 kHz or longer and 1 MHz or shorter. The output power of the laser is preferably 1 W or longer and 200 W or shorter, and more preferably 5 W or longer and 100 W or shorter. The scanning speed of the laser is preferably 100 mm / s or longer and 6000 mm / s or shorter, and more preferably 500 mm / s or longer and 2000 mm / s or shorter.

[0036] While one of the first and second through-holes may be formed by laser processing and the other by etching, punching, or other processes, it is preferable from the viewpoint of corrosion resistance of the solid electrolytic capacitor to form both the first and second through-holes by laser processing.

[0037] The first through-hole H1 and the second through-hole H2 may be formed before forming the mask layer 14, or before forming the solid electrolyte layer 13.

[0038] The overall size of the first sheet is determined by the size, shape, number, arrangement, production capacity, etc., of the element regions and is not particularly limited. The shape of the element regions of the first sheet is not particularly limited, but is preferably rectangular. In this case, the first and second ends may be shorter or longer than the first and second sides.

[0039] The first sheet has multiple element regions from the viewpoint of manufacturing efficiency. In particular, it is preferable that the first sheet has a first element region and a second element region, with the first element region and the second element region being alternately arranged in the length direction, and it is even more preferable that the first element region and the second element region are also alternately arranged in the width direction. When the first element region and the second element region are alternately arranged, the first through-holes are not unevenly distributed in the width direction of the first sheet, so the strength of the sheet is less likely to decrease.

[0040] In the first sheet, when first element regions and second element regions are arranged alternately in the longitudinal direction, it is preferable that the first element region shares a first end and a first through-hole with an adjacent second element region, and also shares a second end and a second through-hole with another adjacent second element region. In this case, the number of cuts required to divide the element region and the amount of material to be discarded can be reduced.

[0041] However, if the first sheet has a first element region and a second element region, the first element region and the second element region do not have to be alternately arranged in the length direction, nor do they have to be alternately arranged in the width direction. Also, if the first element region and the second element region are alternately arranged in the length direction, the first element region does not have to share a first end and a first through hole with an adjacent second element region, nor does it have to share a second end and a second through hole with another adjacent second element region. Furthermore, if the first element region and the second element region are alternately arranged in the width direction, the first element region does not have to share a first side with an adjacent second element region, nor does it have to share a second side with another adjacent second element region.

[0042] The shape of the first through-hole is not particularly limited, as long as it has a width greater than or equal to the width of the element region.

[0043] The shape, number, and arrangement of the second through-holes are not particularly limited, as long as their width is smaller than the width of the element region, but it is preferable that two or more are formed in the width direction within each element region. When two or more second through-holes are formed, it is preferable that these through-holes are formed at equal intervals. If the width of each second through-hole is too small, it becomes difficult to fill with sealing material in the process described later. On the other hand, if the ratio of the total width of the second through-holes to the width of the element region is too large, the proportion of the valve-acting metal substrate exposed on the end face of the solid electrolytic capacitor becomes small, which tends to increase the ESR.

[0044] (B) Step of preparing a second sheet Separate from the above steps, prepare a second sheet. The second sheet is made of a metal foil. Further, the second sheet has a plurality of element regions. In the second sheet, each element region is defined by a first end portion and a second end portion that face each other in the length direction, and a first side portion and a second side portion that face each other in the width direction orthogonal to the length direction. Further, in the second sheet, one or more third through-holes having a width smaller than the width of the element region are formed so as to straddle the first end portion of each element region, and a fourth through-hole having a width equal to or larger than the width of the element region is formed so as to straddle the second end portion of each element region.

[0045] FIG. 2A is a perspective view schematically showing an example of the second sheet, and FIG. 2B is a perspective view of an enlarged part of FIG. 2A. The second sheet 20 shown in FIGS. 2A and 2B has a plurality of element regions R21 (hereinafter referred to as first element regions) and a plurality of element regions R22 (hereinafter referred to as second element regions).

[0046] As shown in FIG. 2B, the first element region R21 is defined by a first end portion E21 and a second end portion E22 that face each other in the length direction (L direction), and a first side portion S21 and a second side portion S22 that face each other in the width direction (W direction) orthogonal to the length direction. A plurality (three in FIG. 2B) of third through-holes H3 are formed so as to straddle the first end portion E21 of the first element region R21 in the length direction, and one fourth through-hole H4 is formed so as to straddle the second end portion E22 of the first element region R21 in the length direction. The third through-holes H3 are composed of a plurality of substantially round holes having a width smaller than the width of the first element region R21, and the fourth through-hole H4 is composed of one long hole having a width equal to or larger than the width of the first element region R21.

[0047] On the other hand, the second element region R22 has the same shape as the first element region R21, but the directions of the first end portion E21 and the second end portion E22 are opposite to those of the first element region R21.

[0048] As shown in FIG. 2A, in the second sheet 20, the first element regions R21 and the second element regions R22 are alternately arranged in the length direction. As shown in FIG. 2B, the first element region R21 shares the first end E21 and the third through hole H3 with the adjacent second element region R22, and also shares the second end E22 and the fourth through hole H4 with another adjacent second element region R22.

[0049] Further, as shown in FIG. 2A, in the second sheet 20, the first element regions R21 and the second element regions R22 are alternately arranged in the width direction. As shown in FIG. 2B, the first element region R21 shares the first side S21 with the adjacent second element region R22, and also shares the second side S22 with another adjacent second element region R22.

[0050] As shown in FIG. 2B, the second sheet 20 is made of a metal foil 21.

[0051] The second sheet is preferably manufactured as follows. First, a metal foil 21 is prepared.

[0052] The metal foil is preferably made of at least one metal selected from the group consisting of aluminum, copper, silver, and alloys mainly composed of these metals. When the metal foil is made of the above metals, the resistance value of the metal foil can be reduced, and the ESR can be reduced.

[0053] In particular, the second sheet (metal foil) is preferably made of an aluminum foil or a copper foil. Although aluminum and copper are easily oxidized in nature, they are suitable for thickening the oxide film by laser processing and improving the corrosion resistance.

[0054] Also, since copper (16.78 nΩm @ 20°C) has a lower resistance than aluminum (28.2 nΩm @ 20°C), when a copper foil is used, the cathode extraction resistance of the solid electrolytic capacitor can be lowered.

[0055] Further, as the metal foil, a metal foil having a carbon coat or a titanium coat formed on the surface by a film forming method such as sputtering or vapor deposition may be used.

[0056] The thickness of the metal foil is not particularly limited, but from the viewpoint of reducing ESR, it is preferable that it be between 5 μm and 100 μm.

[0057] It is preferable that a roughened surface is formed on the surface of the metal foil. When a roughened surface is formed on the surface of the metal foil, the adhesion between the metal foil and the solid electrolyte layer, or between the metal foil and other conductive layers, is improved, and the contact area is increased, thereby reducing ESR. The method for forming the roughened surface is not particularly limited, and it may be formed by etching or the like. In particular when using aluminum, it is preferable to apply a carbon coating or titanium coating to a surface that has been roughened (etched) in order to reduce resistance.

[0058] Furthermore, a coating layer made of an anchor coating agent may be formed on the surface of the metal foil. When a coating layer made of an anchor coating agent is formed on the surface of the metal foil, the adhesion between the metal foil and the solid electrolyte layer, or the adhesion between the metal foil and other conductive layers, is improved, thereby reducing ESR.

[0059] Next, a third through-hole H3 is formed so as to straddle the first end E21 of each element region, and a fourth through-hole H4 is formed so as to straddle the second end E22 of each element region.

[0060] The third and fourth through-holes are formed by laser processing, in which the second sheet is cut while irradiating it with a laser and oxidizing the area around the laser-irradiated part. This allows a passivation film to be formed on the processed portion, which is thicker than the native oxide film. Therefore, the corrosion resistance of the third and fourth through-holes is improved, and the corrosion resistance of the solid electrolytic capacitor is also improved.

[0061] Here, for example, an IR laser, a UV laser, etc., can be used as the laser. The pulse width of the laser is preferably attosecond or longer and millisecond or shorter, and more preferably femtosecond or longer and nanosecond or shorter. The frequency of the laser is preferably 10 kHz or longer and 10 MHz or shorter, and more preferably 100 kHz or longer and 1 MHz or shorter. The output power of the laser is preferably 1 W or longer and 200 W or shorter, and more preferably 5 W or longer and 100 W or shorter. The scanning speed of the laser is preferably 100 mm / s or longer and 6000 mm / s or shorter, and more preferably 500 mm / s or longer and 2000 mm / s or shorter.

[0062] While one of the third and fourth through-holes may be formed by laser processing and the other by etching, punching, or other processes, it is preferable from the viewpoint of corrosion resistance of the solid electrolytic capacitor to form the third and fourth through-holes by laser processing.

[0063] Furthermore, at least one of the first through-hole, second through-hole, third through-hole, and fourth through-hole may be formed by laser processing. However, from the viewpoint of corrosion resistance of the solid electrolytic capacitor, it is preferable to form the first through-hole, second through-hole, third through-hole, and fourth through-hole, respectively, by laser processing.

[0064] Other methods for forming through holes besides laser processing include etching and punching. Among these, punching offers higher productivity compared to laser processing and etching.

[0065] The overall size of the second sheet is not particularly limited, but it is preferable that it be the same as the overall size of the first sheet. The shape, number, and arrangement of the element regions of the second sheet are preferably the same as the shape, number, and arrangement of the element regions of the opposing first sheet.

[0066] The second sheet has multiple element regions from the viewpoint of manufacturing efficiency. In particular, it is preferable that the second sheet has a first element region and a second element region, with the first and second element regions being alternately arranged in the length direction, and it is even more preferable that the first and second element regions are also alternately arranged in the width direction. When the first and second element regions are alternately arranged, the fourth through-holes are not unevenly distributed in the width direction of the second sheet, so the strength of the sheet is less likely to decrease.

[0067] In the second sheet, when the first element regions and the second element regions are arranged alternately in the longitudinal direction, it is preferable that the first element region shares a first end and a third through-hole with an adjacent second element region, and also shares a second end and a fourth through-hole with another adjacent second element region. In this case, the number of cuts required to divide the element region and the amount of material to be discarded can be reduced.

[0068] However, if the second sheet has a first element region and a second element region, the first element region and the second element region do not have to be alternately arranged in the length direction, nor do they have to be alternately arranged in the width direction. Also, if the first element region and the second element region are alternately arranged in the length direction, the first element region does not have to share a first end and a third through hole with an adjacent second element region, nor does it have to share a second end and a fourth through hole with another adjacent second element region. Furthermore, if the first element region and the second element region are alternately arranged in the width direction, the first element region does not have to share a first side with an adjacent second element region, nor does it have to share a second side with another adjacent second element region.

[0069] The shape, number, and arrangement of the third through-holes are not particularly limited, as long as they have a width smaller than the width of the element region, but it is preferable that two or more are formed in the width direction within each element region. When two or more third through-holes are formed, it is preferable that these through-holes are formed at equal intervals. If the width of each third through-hole is too small, it becomes difficult to fill with sealing material in the process described later, while if the ratio of the total width of the third through-holes to the width of the element region is too large, the proportion of metal foil exposed on the end face of the solid electrolytic capacitor decreases, which tends to increase the ESR.

[0070] The shape of the fourth through-hole is not particularly limited, as long as it has a width greater than or equal to the width of the element region.

[0071] (C) Process for manufacturing a laminated sheet A laminated sheet is manufactured by stacking a first sheet and a second sheet such that the first ends and second ends of each element region face each other. In the resulting laminated sheet, the first through hole and the third through hole, and the second through hole and the fourth through hole are in communication in the stacking direction.

[0072] Preferably, the second and third through holes are linearly connected from the first main surface of the laminated sheet toward the second main surface.

[0073] When laminating the first sheet and the second sheet, the valve-acting metal substrate and the metal foil are connected without interposing other conductive layers of the solid electrolyte layer. In this way, by laminating the first sheet and the second sheet without using adhesive, the thickness of the solid electrolytic capacitor can be reduced. However, if the adhesive does not affect the thickness of the solid electrolytic capacitor, the first sheet and the second sheet may be bonded together using an adhesive.

[0074] When laminating the first sheet and the second sheet, it is preferable to place the metal foil on the layer located beneath it while it is still viscous. The solid electrolyte layer is viscous before drying, making it suitable for direct placement of the metal foil. On the other hand, if the solid electrolyte layer located beneath the metal foil is dried, it becomes difficult to adhere the metal foil, so it is preferable to place a conductive adhesive layer (for example, a solid electrolyte layer containing a binder) before placing the metal foil.

[0075] Figure 3A is a schematic perspective view showing an example of the state before the first sheet and the second sheet are laminated, and Figure 3B is a schematic perspective view showing an example of a laminated sheet. As shown in Figure 3A, the laminated sheet 30 shown in Figure 3B is obtained by alternately laminating the first sheet 10 and the second sheet 20. The laminated sheet 30 has a first main surface M31 and a second main surface M32 that are opposite each other in the lamination direction (T direction).

[0076] Figures 3A and 3B show an example in which five sheets each of the first sheet 10 and the second sheet 20 are laminated, with the second sheet 20 placed on the first main surface M31 and the first sheet 10 on the second main surface M32 of the laminated sheet 30. However, the number of first and second sheets to be laminated is not particularly limited. The number of first sheets and second sheets may be the same or different. Therefore, either the first sheet or the second sheet may be placed on the main surface of the laminated sheet. Furthermore, when manufacturing the laminated sheet, the first and second sheets may be laminated on a substrate made of glass epoxy resin or the like.

[0077] (D) Steps for manufacturing a laminated block A laminated block is manufactured by filling the first through-hole and the third through-hole, and the second through-hole and the fourth through-hole, from at least one main surface side of the obtained laminated sheet with sealing material.

[0078] As described above, in the laminated sheet, the first through-hole and the third through-hole, and the second through-hole and the fourth through-hole are in communication in the lamination direction, so that sealing material can be filled into each through-hole from the main surface side of the laminated sheet. As a result, in the resulting laminated block, a first sealing portion is formed that fills the first through-hole and the third through-hole, and a second sealing portion is formed that fills the second through-hole and the fourth through-hole.

[0079] The sealing material can be filled by, for example, a molding resin molding method. In this case, in addition to the first sealing portion and the second sealing portion, a third sealing portion that covers at least one main surface of the laminated sheet can be formed at the same time. Thus, in the step of manufacturing the laminated block (D), it is preferable to simultaneously perform the step of covering at least one main surface of the laminated sheet with the sealing material.

[0080] Figure 4A is a schematic perspective view showing an example of a laminated block body, and Figure 4B is an enlarged perspective view of a part of Figure 4A that has been disassembled. In the laminated block body 40 shown in Figure 4A, by filling the first through hole and the third through hole, and the second through hole and the fourth through hole with sealing material, a first sealing portion 131 that fills the first through hole H1 and the third through hole H3, and a second sealing portion 132 that fills the second through hole H2 and the fourth through hole H4 are formed, as shown in Figure 4B. Furthermore, as shown in Figure 4A, the laminated block body 40 also includes a third sealing portion 133 that covers each main surface.

[0081] The encapsulant comprises at least a resin, preferably a resin and a filler. Examples of resins included in the encapsulant include epoxy resins and phenolic resins. Examples of fillers included in the encapsulant include metal oxide particles such as silica particles and alumina particles.

[0082] When the sealing material includes resin and filler, it is preferable that the maximum diameter of the filler be smaller than the minimum diameter of the second and third through holes, from the viewpoint of ensuring the sealing material's filling capacity. The diameter of the through hole refers to the diameter if the cross-sectional shape is circular, or the maximum length passing through the center of the cross-section if the cross-sectional shape is not circular.

[0083] Furthermore, when the sealing material includes resin and filler, it is preferable that the maximum diameter of the filler be smaller than the minimum thickness of the metal foil, from the viewpoint of ensuring the sealing material's filling properties.

[0084] The maximum diameter of the filler contained in the sealing material is preferably in the range of, for example, 30 μm or more and 40 μm or less.

[0085] However, the step of (D) manufacturing the laminated block is optional. That is, in the first embodiment, the laminated block is manufactured as needed.

[0086] (E) Process for producing multiple element stacks by cutting a stacked block: A stacked block is cut at the positions of the first end and the second end of each element region, and also at the positions of the first side and the second side of each element region, thereby producing multiple element stacks.

[0087] Figure 5A is a schematic plan view showing the valve-acting metal substrate before cutting, and Figure 5B is a schematic plan view showing the valve-acting metal substrate after cutting. As shown in Figure 5A, the valve-acting metal substrate 11 constituting the first sheet included in the laminated block has a first sealing portion 131 that fills a first through hole H1 spanning the first end E11 of each element region, and a second sealing portion 132 that fills a second through hole H2 spanning the second end E12 of each element region.

[0088] Therefore, when the valve-acting metal substrate 11 is cut with a guillotine blade or the like, applying ultrasonic vibration, at the positions of the first end E11 and the second end E12 of each element region, separating the first sealing portion 131 and the second sealing portion 132 on both sides, as shown in Figure 5B, the first sealing portion 131 is exposed on the first end face E101, which is the cut surface on the first end E11 side, while the valve-acting metal substrate 11 is not exposed. On the other hand, the valve-acting metal substrate 11 and the second sealing portion 132 are exposed on the second end face E102, which is the cut surface on the second end E12 side.

[0089] Furthermore, as shown in Figure 5B, the valve-acting metal substrate 11, which has a porous portion (not shown) on its surface, has a third end face E3 located on the first end face E101 side and covered by the first sealing portion 131, and a fourth end face E4 located on the second end face E102 side and facing the second sealing portion 132.

[0090] The third end face E3 is formed from the remaining portion of the wall surface constituting the first through hole H1, and the fourth end face E4 is formed from the remaining portion of the wall surface constituting the second through hole H2. Therefore, an oxide film 2 is formed on both the third end face E3 and the fourth end face E4. Since this oxide film 2 is thicker than the native oxide film, the corrosion resistance of the third end face E3 and the fourth end face E4 is improved, and the corrosion resistance of the solid electrolytic capacitor is also improved.

[0091] In addition, one of the first through-hole H1 and the second through-hole H2 may be formed by laser processing, and the other by etching or punching, etc., and an oxide film 2 may be formed on one of the third end face E3 and the fourth end face E4, but it is not necessary to form an oxide film 2 on the other. However, from the viewpoint of corrosion resistance of the solid electrolytic capacitor, it is preferable that an oxide film 2 is formed on the third end face E3 and the fourth end face E4, respectively.

[0092] Furthermore, when the valve-acting metal substrate 11 is cut at the positions of the first side portion S11 and the second side portion S12 of each element region with a guillotine blade or the like that is subjected to ultrasonic vibration, the valve-acting metal substrate 11 is exposed on both cut surfaces, as shown in Figure 5B.

[0093] Figure 6A is a schematic plan view showing the metal foil before cutting, and Figure 6B is a schematic plan view showing the metal foil after cutting. As shown in Figure 6A, the metal foil 21 constituting the second sheet included in the laminated block has a first sealing portion 131 that fills a third through hole H3 spanning the first end E21 of each element region, and a second sealing portion 132 that fills a fourth through hole H4 spanning the second end E22 of each element region.

[0094] Therefore, when the metal foil 21 is cut with a guillotine blade or the like, with ultrasonic vibration applied, at the positions of the first end E21 and the second end E22 of each element region, separating the first sealing portion 131 and the second sealing portion 132 on both sides, as shown in Figure 6B, the metal foil 21 and the first sealing portion 131 are exposed at the first end face E101, which is the cut surface on the first end E21 side. On the other hand, the second sealing portion 132 is exposed at the second end face E102, which is the cut surface on the second end E22 side, and the metal foil 21 is not exposed.

[0095] Furthermore, as shown in Figure 6B, the metal foil 21 has a fifth end face E5 located on the side of the first end face E101 and facing the first sealing portion 131, and a sixth end face E6 located on the side of the second end face E102 and covered by the second sealing portion 132.

[0096] The fifth end face E5 is formed from the remaining portion of the wall surface constituting the third through hole H3, and the sixth end face E6 is formed from the remaining portion of the wall surface constituting the fourth through hole H4. Therefore, an oxide film 2 is formed on the fifth end face E5 and the sixth end face E6, respectively. Since this oxide film 2 is thicker than the native oxide film, the corrosion resistance of the fifth end face E5 and the sixth end face E6 is improved, and the corrosion resistance of the solid electrolytic capacitor is also improved.

[0097] In addition, one of the third through-hole H3 and the fourth through-hole H4 may be formed by laser processing, and the other by etching or punching, etc., and an oxide film 2 may be formed on one of the fifth end face E5 and the sixth end face E6, but it is not necessary to form an oxide film 2 on the other. However, from the viewpoint of corrosion resistance of the solid electrolytic capacitor, it is preferable that an oxide film 2 is formed on the fifth end face E5 and the sixth end face E6, respectively.

[0098] Furthermore, an oxide film may be formed on at least one of the third, fourth, fifth, and sixth end faces, but from the viewpoint of corrosion resistance of the solid electrolytic capacitor, it is preferable to form an oxide film on the third, fourth, fifth, and sixth end faces, respectively.

[0099] Furthermore, when the metal foil 21 is cut at the positions of the first side portion S21 and the second side portion S22 of each element region with a guillotine blade or the like that which is subjected to ultrasonic vibration, the metal foil 21 is exposed on both cut surfaces, as shown in Figure 6B.

[0100] As described above, by cutting the laminated block at the positions of the first and second ends of each element region, the metal foil and the first sealing portion can be exposed on the first end face of the resulting element laminate, and the valve-acting metal substrate and the second sealing portion can be exposed on the second end face.

[0101] Furthermore, since both the metal foil and the valve-acting metal substrate are exposed at the cut surfaces obtained by cutting the laminated block at the positions of the first and second sides of each element region, it is preferable to form a fourth sealing portion that covers each side surface of the element laminate.

[0102] Figure 7 is a schematic cross-sectional view showing an example of an element stack. Figures 8A and 8B are schematic perspective views showing an example of an element stack. Note that Figure 7 is a cross-sectional view taken along line A-A of the element stack shown in Figure 8A.

[0103] In the element laminate 100 shown in Figures 7, 8A, and 8B, as shown in Figure 7, a first layer 110 comprising a valve-acting metal substrate 11 having a porous portion 12 on its surface, a dielectric layer (not shown) formed on the surface of the porous portion, and a solid electrolyte layer 13 provided on the dielectric layer, is laminated with a second layer 120 made of metal foil 21. The first layer 110 and the second layer 120 are laminated alternately along the lamination direction (T direction), but considering weather resistance such as moisture resistance and heat resistance, it is preferable that the second layer 120, which is metal foil, is located at the outermost layers (excluding the third sealing portion 133) opposite each other in the lamination direction, as shown in Figure 7. Note that the mask layer 14 is omitted in Figures 7, 8A, and 8B.

[0104] As shown in Figures 7, 8A, and 8B, the element stack 100 has a first main surface M101 and a second main surface M102 that are opposite each other in the stacking direction (T direction), a first end surface E101 and a second end surface E102 that are opposite each other in the length direction (L direction) perpendicular to the stacking direction, and a first side surface S101 and a second side surface S102 that are opposite each other in the width direction (W direction) perpendicular to the stacking direction and the length direction.

[0105] As shown in Figures 7 and 8A, the metal foil 21 and the first sealing portion 131 are exposed on the first end face E101 of the element stack 100. On the other hand, as shown in Figures 7 and 8B, the valve-acting metal substrate 11 and the second sealing portion 132 are exposed on the second end face E102 of the element stack 100. Although the dielectric layer is also exposed on the second end face E102 of the element stack 100, in the following description it will simply be stated as "the valve-acting metal substrate 11 and the second sealing portion 132 are exposed."

[0106] Furthermore, the element stack 100 includes a third sealing portion 133 that covers each main surface, and a fourth sealing portion 134 that covers each side surface.

[0107] The element stack is fabricated, for example, as follows:

[0108] First, the laminated block is cut along the first and second sides of each element region using a guillotine blade while applying ultrasonic vibrations.

[0109] Figure 9A is a schematic perspective view showing an example of a laminated block body after cutting, and Figure 9B is a perspective view showing a part of Figure 9A disassembled and enlarged. For example, a laminated block body 40a is produced by cutting the laminated block body 40 shown in Figure 4A along the first and second sides of each element region, as shown in Figures 9A and 9B, thereby forming a gap G along the first and second sides. For cutting the laminated block body at this time, methods such as dicing using a dicing blade, a guillotine blade without ultrasonic vibration, laser processing, and scribing can be applied, in addition to a guillotine blade with ultrasonic vibration. In the laminated block body 40a, as shown in Figure 9B, the metal foil 21 and the valve-acting metal substrate 11 are exposed on the cut surface that appears after cutting.

[0110] Although not shown in the figures, the thickness of the exposed portion of the metal foil 21 and the valve-acting metal substrate 11 (thickness in the T direction) is greater than the thickness of the unexposed portion of the metal foil 21 and valve-acting metal substrate 11, and may widen in a tapered shape both vertically and horizontally in the thickness direction.

[0111] Next, a sealing material is filled into the gaps formed in the laminated block. This forms a fourth sealing portion that fills the gaps. As the sealing material, for example, the sealing material used to form the first sealing portion and the second sealing portion can be used.

[0112] Figure 10A is a schematic perspective view showing an example of a laminated block body in which a fourth sealing portion is formed, and Figure 10B is a perspective view obtained by disassembling and enlarging a part of Figure 10A. By filling the gap G of the laminated block body 40a shown in Figure 9A with a sealing material, a laminated block body 40b is produced in which a fourth sealing portion 134 that fills the gap G is formed, as shown in Figures 10A and 10B.

[0113] Subsequently, the laminated block is cut at the positions of the first and second ends of each element region so as to separate the first sealing portion 131 and the second sealing portion 132 on both sides, and at the positions of the first and second sides of each element region so as to separate the fourth sealing portion 134 on both sides. This allows the element laminate to be separated into individual pieces, with the first and second sides insulated by the sealing portions. For cutting the laminated block at this time, methods such as dicing using a dicing blade, a guillotine blade without ultrasonic vibration, laser processing, or scribing can be applied, in addition to a guillotine blade with ultrasonic vibration. When laminating the first and second sheets on a substrate made of glass epoxy resin or the like, it is preferable to cut the substrate to a half-cut position in order to reliably cut the second sheet, which is a metal foil. By half-cutting, a stepped shape is created from the first and second sides of each element region to the substrate, and this stepped shape is filled with a part of the fourth sealing portion 134.

[0114] Figure 11A is a schematic perspective view showing an example of a fragmented element stack, and Figure 11B is a perspective view showing a part of Figure 11A disassembled and enlarged. The element stack 100 shown in Figure 11A is obtained by cutting the stacked block 40b shown in Figure 10A at the positions of the first end and the second end of each element region, and also at the positions of the first side and the second side of each element region. In this case, as shown in Figures 11A and 11B, the stacked block 40b is cut such that the cut surfaces that appear when cut at the positions of the first side and the second side constitute the fourth sealing portion 134.

[0115] (F) Step of forming the first and second external electrodes The first and second external electrodes are formed on the obtained element stack. In the first embodiment, the first external electrode is formed on the first end face and the second external electrode is formed on the second end face. A solid electrolytic capacitor is obtained by doing the above.

[0116] Figure 12 is a schematic cross-sectional view showing an example of a solid electrolytic capacitor. The solid electrolytic capacitor 1 shown in Figure 12 comprises an element stack 100 as shown in Figure 7, a first external electrode 141 provided on the first end face E101 of the element stack 100, and a second external electrode 142 provided on the second end face E102 of the element stack 100. The first external electrode 141 is connected to a metal foil 21 exposed on the first end face E101, and the second external electrode 142 is connected to a valve-acting metal substrate 11 exposed on the second end face E102.

[0117] The first and second external electrodes can be formed, for example, by plating, sputtering, immersion coating, printing, etc. In the case of plating, the plating layers can be a Zn-Ag-Ni layer, an Ag-Ni layer, a Ni layer, a Zn-Ni-Au layer, a Ni-Au layer, a Zn-Ni-Cu layer, a Ni-Cu layer, etc. It is preferable to further form plating layers on these plating layers in the order of, for example, a Cu plating layer, a Ni plating layer, and a Sn plating layer (or with some exceptions).

[0118] In the method for manufacturing a solid electrolytic capacitor according to the first embodiment of the present invention, at least one of the first, second, third, and fourth through-holes is formed by laser processing, so that an oxide film thicker than the native oxide film can be formed as a passivation film in the processed portion. As a result, the corrosion resistance in the through-hole is improved, and a solid electrolytic capacitor with excellent corrosion resistance can be manufactured.

[0119] [Solid electrolytic capacitor] A solid electrolytic capacitor obtained by the manufacturing method described above is also one of the present inventions.

[0120] The solid electrolytic capacitor of the present invention comprises an element laminate in which a first layer and a second layer are stacked, a first external electrode provided on a first end face of the element laminate, and a second external electrode provided on a second end face of the element laminate.

[0121] The first layer of the element stack comprises a valve-acting metal substrate having a porous surface, a dielectric layer formed on the surface of the porous surface, and a solid electrolyte layer provided on the dielectric layer. The second layer consists of a metal foil. The metal foil and the first sealing portion are exposed at the first end face of the element stack, and the valve-acting metal substrate and the second sealing portion are exposed at the second end face. The first external electrode is connected to the metal foil exposed at the first end face, and the second external electrode is connected to the valve-acting metal substrate exposed at the second end face.

[0122] The valve-acting metal substrate has a third end face located on the first end face side and covered by the first sealing portion, and a fourth end face located on the second end face side and facing the second sealing portion. The metal foil has a fifth end face located on the first end face side and facing the first sealing portion, and a sixth end face located on the second end face side and covered by the second sealing portion.

[0123] The basic configuration of the element stack, the first external electrode, and the second external electrode is as described in [Method for Manufacturing Solid Electrolytic Capacitors], so a detailed explanation will be omitted.

[0124] In the solid electrolytic capacitor according to the first embodiment of the present invention, an oxide film is formed on at least one of the third and fourth end faces of the valve-acting metal substrate and the fifth and sixth end faces of the metal foil.

[0125] Figures 13A and 13B are schematic perspective views showing an example of a solid electrolytic capacitor according to the first embodiment of the present invention. Figure 12 is a cross-sectional view taken along line A-A of the solid electrolytic capacitor shown in Figure 13A. The solid electrolytic capacitor 1 shown in Figures 13A and 13B comprises an element stack 100, a first external electrode 141, and a second external electrode 142. In Figures 13A and 13B, a part of the element stack 100, the first external electrode 141, and the second external electrode 142 are shown with dashed lines. Also, as in Figures 8A and 8B, the mask layer 14 is omitted.

[0126] In the element laminate 100, as shown in Figure 7, a first layer 110 comprising a valve-acting metal substrate 11 having a porous portion 12 on its surface, a dielectric layer (not shown) formed on the surface of the porous portion, and a solid electrolyte layer 13 provided on the dielectric layer, is laminated with a second layer 120 made of metal foil 21.

[0127] As shown in Figure 13A, the metal foil 21 and the first sealing portion 131 are exposed on the first end face E101 of the element stack 100.

[0128] On the other hand, as shown in Figure 13B, the valve-acting metal substrate 11 and the second sealing portion 132 are exposed at the second end face E102 of the element stack 100.

[0129] Figure 14 is a schematic diagram showing an example of a cross-section passing through the valve-acting metal substrate of the element stack shown in Figures 13A and 13B. As shown in Figure 14, the valve-acting metal substrate 11 has a third end face E3 located on the first end face E101 side and covered by the first sealing portion 131, and a fourth end face E4 located on the second end face E102 side and opposite the second sealing portion 132, and an oxide film 2 is formed on the third end face E3 and the fourth end face E4, respectively. Here, the third end face E3 constitutes one side of the valve-acting metal substrate 11 on the first end face E101 side, and the fourth end face E4 corresponds to the end face that constitutes the notch provided on the second end face E102 side of the valve-acting metal substrate 11. Note that these third end face E3 and fourth end face E4 are also provided on the porous portion 12, and an oxide film 2 is also formed on the porous portion 12 that constitutes the third end face E3 and the fourth end face E4.

[0130] Figure 15 is a schematic diagram showing an example of a cross-section passing through the metal foil of the element stack shown in Figures 13A and 13B. As shown in Figure 15, the metal foil 21 has a fifth end face E5 located on the first end face E101 side and opposite the first sealing portion 131, and a sixth end face E6 located on the second end face E102 side and covered by the second sealing portion 132, and an oxide film 2 is formed on the fifth end face E5 and the sixth end face E6, respectively. Here, the fifth end face E5 corresponds to the end face that constitutes the notch provided on the first end face E101 side of the metal foil 21, and the sixth end face E6 constitutes one side of the metal foil 21 on the second end face E102 side.

[0131] The third end face E3, the fourth end face E4, the fifth end face E5, and the sixth end face E6 are adjacent to the sealing portion, and therefore there is a concern that they may be corroded by moisture entering from the outside. For this reason, an oxide film 2 is formed on each of the third end face E3, the fourth end face E4, the fifth end face E5, and the sixth end face E6. As described above, these oxide films 2 act as a passivation film that is thicker than the natural oxide film formed by laser processing, thus improving the corrosion resistance of the third end face E3, the fourth end face E4, the fifth end face E5, and the sixth end face E6. As a result, the corrosion resistance of the entire solid electrolytic capacitor 1 can be improved.

[0132] Therefore, according to the solid electrolytic capacitor of the first embodiment of the present invention, a solid electrolytic capacitor with excellent corrosion resistance can be realized.

[0133] While an oxide film may be formed on at least one of the third, fourth, fifth, and sixth end faces, it is preferable to form an oxide film on the third, fourth, fifth, and sixth end faces, respectively, from the viewpoint of corrosion resistance of the solid electrolytic capacitor.

[0134] Furthermore, since the portion exposed to the second end face E102 of the valve-acting metal substrate 11 and the portion exposed to the first end face E101 of the metal foil 21 are directly covered by the first external electrode and the second external electrode, respectively, there is no contact with moisture and no corrosion occurs.

[0135] (Second Embodiment) [Method for Manufacturing Solid Electrolytic Capacitors] In the method for manufacturing solid electrolytic capacitors according to the second embodiment of the present invention, in step (E), a stacked block is cut at the positions of the first end and the second end of each element region, and a plurality of element stacks are manufactured by cutting with a laser at the positions of the first side and the second side of each element region. As a result, corrosion resistance at the first side and the second side is improved, and the corrosion resistance of the solid electrolytic capacitor is further improved. However, in the second embodiment, the laser processing distance is longer than in the first embodiment, so productivity is better in the first embodiment.

[0136] Figure 16A is a schematic perspective view showing another example of a laminated block after cutting, and Figure 16B is a perspective view that is an enlarged and disassembled view of a part of Figure 16A. For example, as shown in Figures 16A and 16B, the laminated block 40 shown in Figure 4A is cut with a laser along the first and second sides of each element region to produce a laminated block 40a in which a gap G is formed along the first and second sides. At this time, the laminated block 40 is cut while irradiating it with a laser and oxidizing the area around the laser-irradiated part. As a result, an oxide film 2 thicker than the natural oxide film can be formed as a passivation film on the processed part. As a result, in the laminated block 40a, as shown in Figure 16B, the metal foil 21 is covered with the oxide film 2 on the cut side surface exposed by the cutting, and the valve-acting metal substrate 11 is also covered with the oxide film 2. In addition, the porous part 12 is also covered with the oxide film 2 on the cut side surface.

[0137] Here, for example, an IR laser, a UV laser, etc., can be used as the laser. The pulse width of the laser is preferably attosecond or longer and millisecond or shorter, and more preferably femtosecond or longer and nanosecond or shorter. The frequency of the laser is preferably 10 kHz or longer and 10 MHz or shorter, and more preferably 100 kHz or longer and 1 MHz or shorter. The output power of the laser is preferably 1 W or longer and 200 W or shorter, and more preferably 5 W or longer and 100 W or shorter. The scanning speed of the laser is preferably 100 mm / s or longer and 6000 mm / s or shorter, and more preferably 500 mm / s or longer and 2000 mm / s or shorter.

[0138] The subsequent steps are the same as in the first embodiment. A solid electrolytic capacitor is obtained as a result.

[0139] According to the method for manufacturing a solid electrolytic capacitor as embodied in the second embodiment of the present invention, a solid electrolytic capacitor with superior corrosion resistance can be manufactured.

[0140] [Solid electrolytic capacitor] A solid electrolytic capacitor obtained by the manufacturing method described above is also one of the present inventions.

[0141] The solid electrolytic capacitor according to the second embodiment of the present invention is similar to the first embodiment in that an oxide film is formed on at least one of the third and fourth end faces of the valve-acting metal substrate and the fifth and sixth end faces of the metal foil, but an oxide film is also formed on the first and second side surfaces of the valve-acting metal substrate and the third and fourth side surfaces of the metal foil, respectively.

[0142] Figures 17A and 17B are schematic perspective views showing an example of a solid electrolytic capacitor according to a second embodiment of the present invention. The solid electrolytic capacitor 1A shown in Figures 17A and 17B comprises an element stack 100A, a first external electrode 141, and a second external electrode 142. In Figures 17A and 17B, a portion of the element stack 100A, the first external electrode 141, and the second external electrode 142 are shown with dashed lines. Also, as in Figures 8A and 8B, the mask layer 14 is omitted.

[0143] In the element laminate 100A, as shown in Figure 7, a first layer 110 comprising a valve-acting metal substrate 11 having a porous portion 12 on its surface, a dielectric layer (not shown) formed on the surface of the porous portion, and a solid electrolyte layer 13 provided on the dielectric layer, is laminated with a second layer 120 made of metal foil 21.

[0144] As shown in Figure 17A, the metal foil 21 and the first sealing portion 131 are exposed on the first end face E101 of the element stack 100A.

[0145] On the other hand, as shown in Figure 17B, the valve-acting metal substrate 11 and the second sealing portion 132 are exposed at the second end face E102 of the element stack 100A.

[0146] Figure 18 is a schematic diagram showing an example of a cross-section passing through the valve-acting metal substrate of the element stack shown in Figures 17A and 17B. As shown in Figure 18, the valve-acting metal substrate 11 has a third side surface S3 located on the first side surface S101 side and covered by a fourth sealing portion 134, and a fourth side surface S4 located on the second side surface S102 side and covered by a fourth sealing portion 134. In addition to the third end face E3 and the fourth end face E4, oxide films 2 are formed on the third side surface S3 and the fourth side surface S4, respectively. Here, the third side surface S3 constitutes one side of the valve-acting metal substrate 11 on the first side surface S101 side, and the fourth side surface S4 constitutes one side of the valve-acting metal substrate 11 on the second side surface S102 side. Furthermore, these third side surface S3 and fourth side surface S4 are also provided in the porous portion 12, and the oxide film 2 is also formed on the porous portion 12 that constitutes the third side surface S3 and fourth side surface S4.

[0147] Figure 19 is a schematic diagram showing an example of a cross-section through the metal foil of the element stack shown in Figures 17A and 17B. As shown in Figure 19, the metal foil 21 has a fifth side surface S5 located on the first side surface S101 side and covered by a fourth sealing portion 134, and a sixth side surface S6 located on the second side surface S102 side and covered by a fourth sealing portion 134. In addition to the fifth end face E5 and the sixth end face E6, an oxide film 2 is formed on the fifth side surface S5 and the sixth side surface S6, respectively. Here, the fifth side surface S5 constitutes one side of the metal foil 21 on the first side surface S101 side, and the sixth side surface S6 constitutes one side of the metal foil 21 on the second side surface S102 side.

[0148] As described above, these oxide films 2 are thicker than the native oxide film formed by laser processing, and therefore exhibit excellent corrosion resistance not only on the third end face E3, fourth end face E4, fifth end face E5, and sixth end face E6, but also on the third side face S3, fourth side face S4, fifth side face S5, and sixth side face S6. As a result, the corrosion resistance of the entire solid electrolytic capacitor 1 can be further improved.

[0149] Therefore, according to the solid electrolytic capacitor of the second embodiment of the present invention, a solid electrolytic capacitor with superior corrosion resistance can be realized.

[0150] (Third Embodiment) [Method for Manufacturing a Solid Electrolytic Capacitor] In the method for manufacturing a solid electrolytic capacitor according to the third embodiment of the present invention, in step (A), at least one of the first through-hole and the second through-hole is formed by laser processing, but in step (B), the third through-hole and the fourth through-hole are formed by a method other than laser processing, such as punching. The anode of the solid electrolytic capacitor is formed from the first sheet in which the first and second through-holes are formed, and the cathode of the solid electrolytic capacitor is formed from the second sheet in which the third and fourth through-holes are formed. When a voltage is applied to the solid electrolytic capacitor, the cathode has higher corrosion resistance than the anode. This is because corrosion is less likely to occur inside the solid electrolytic capacitor on the cathode side, which has a lower electrochemical potential when a voltage is applied. Therefore, it is considered that forming the first and second through-holes in the first sheet, which becomes the anode, by laser processing will have a greater overall effect on improving corrosion resistance compared to forming the third and fourth through-holes in the second sheet, which becomes the cathode, by laser processing. On the other hand, punching and similar processes offer higher productivity compared to laser processing. Therefore, according to the manufacturing method for solid electrolytic capacitors of the third embodiment, it is possible to effectively improve corrosion resistance while also increasing productivity.

[0151] The subsequent steps are the same as in the first embodiment. A solid electrolytic capacitor is obtained as a result.

[0152] According to the method for manufacturing a solid electrolytic capacitor of the third embodiment of the present invention, a solid electrolytic capacitor with excellent corrosion resistance can be efficiently manufactured.

[0153] [Solid electrolytic capacitor] A solid electrolytic capacitor obtained by the manufacturing method described above is also one of the present inventions.

[0154] The solid electrolytic capacitor according to the third embodiment of the present invention is similar to the first embodiment in that an oxide film is formed on at least one of the third and fourth end faces of the valve-acting metal substrate, but no oxide film is formed on the fifth and sixth end faces of the metal foil.

[0155] Figures 20A and 20B are schematic perspective views showing an example of a solid electrolytic capacitor according to a third embodiment of the present invention. The solid electrolytic capacitor 1B shown in Figures 20A and 20B comprises an element stack 100B, a first external electrode 141, and a second external electrode 142. In Figures 20A and 20B, a portion of the element stack 100B, the first external electrode 141, and the second external electrode 142 are shown with dashed lines. Also, as in Figures 8A and 8B, the mask layer 14 is omitted.

[0156] In the element laminate 100B, as shown in Figure 7, a first layer 110 comprising a valve-acting metal substrate 11 having a porous portion 12 on its surface, a dielectric layer (not shown) formed on the surface of the porous portion, and a solid electrolyte layer 13 provided on the dielectric layer, is laminated with a second layer 120 made of metal foil 21.

[0157] As shown in Figure 20A, the metal foil 21 and the first sealing portion 131 are exposed on the first end face E101 of the element stack 100B.

[0158] On the other hand, as shown in Figure 20B, the valve-acting metal substrate 11 and the second sealing portion 132 are exposed at the second end face E102 of the element stack 100B.

[0159] Figure 21 is a schematic diagram showing an example of a cross-section passing through the valve-acting metal substrate of the element stack shown in Figures 20A and 20B. As shown in Figure 21, an oxide film 2 is formed on the third end face E3 and the fourth end face E4 of the valve-acting metal substrate 11. These third end face E3 and fourth end face E4 are also provided on the porous portion 12, and an oxide film 2 is also formed on the porous portion 12 that constitutes the third end face E3 and the fourth end face E4.

[0160] As described above, these oxide films 2 are thicker than the native oxide film formed by laser processing, and therefore exhibit excellent corrosion resistance at the third end face E3 and the fourth end face E4. This improves the overall corrosion resistance of the solid electrolytic capacitor 1.

[0161] Figure 22 is a schematic diagram showing an example of a cross-section through the metal foil of the element stack shown in Figures 20A and 20B. As shown in Figure 22, the metal foil 21 does not have an oxide film 2 formed on the fifth end face E5 and the sixth end face E6, respectively.

[0162] Therefore, although the fifth end face E5 and the sixth end face E6 have inferior corrosion resistance compared to the third end face E3 and the fourth end face E4, they can be manufactured productively by punching or other processes.

[0163] Therefore, according to the solid electrolytic capacitor of the third embodiment of the present invention, a solid electrolytic capacitor with excellent corrosion resistance and productivity can be realized.

[0164] (Fourth Embodiment) [Method for Manufacturing Solid Electrolytic Capacitors] In the method for manufacturing solid electrolytic capacitors according to the fourth embodiment of the present invention, the step of manufacturing the laminated block body (D) described in the first embodiment is omitted. The other steps are the same as in the first, second, or third embodiment.

[0165] Therefore, in the fourth embodiment, in step (E), multiple element stacks are produced by cutting the laminated sheet. More specifically, multiple element stacks are produced by cutting the laminated sheet at the positions of the first and second ends of each element region, as well as at the positions of the first and second sides of each element region.

[0166] In the fourth embodiment, after cutting the laminated sheet, a sealing material can be applied to the necessary locations on the end face of the element laminate.

[0167] In the first embodiment, the element laminate with the fourth sealing portion is manufactured in one piece by cutting the laminated block twice along the first and second sides of each element region. In contrast, in the fourth embodiment, the element laminate with the fourth sealing portion may be manufactured in one piece by cutting the laminated sheet twice along the first and second sides of each element region, or the fourth sealing portion may be formed by cutting the laminated sheet at the positions of the first and second sides of each element region and then applying a sealing material to each cut surface.

[0168] In the fourth embodiment, the method for forming the first external electrode and the second external electrode on the element stack in step (F) is not limited to the method described in the first embodiment. For example, resin electrodes containing Ag or Cu may be used as the first and second external electrodes. Lead terminals may also be connected to the first and second external electrodes.

[0169] As described above, a solid electrolytic capacitor can be obtained. In the method for manufacturing a solid electrolytic capacitor according to the fourth embodiment of the present invention, a solid electrolytic capacitor with excellent corrosion resistance can be manufactured, similar to the first embodiment.

[0170] The solid electrolytic capacitor obtained by the manufacturing method described above is also one of the present inventions.

[0171] (Fifth Embodiment) [Method for Manufacturing Solid Electrolytic Capacitors] In the method for manufacturing solid electrolytic capacitors according to the fifth embodiment of the present invention, the step of manufacturing the laminated block body (D) described in the first embodiment is omitted.

[0172] Therefore, in the fifth embodiment, in step (E), multiple element stacks are manufactured by cutting the laminated sheet. More specifically, in the fifth embodiment, the element stacks are manufactured as follows.

[0173] First, the laminated sheet is cut along the first and second sides of each element region using a guillotine blade while applying ultrasonic vibrations, thereby forming multiple strip-shaped laminated sheets.

[0174] Figure 23 is a schematic perspective view showing an example of a laminated sheet after cutting. For example, the laminated sheet 30 shown in Figure 3B is cut along the first and second sides (cutting line S111) of each element region with a guillotine blade or the like while applying ultrasonic vibration, as shown in Figure 23. As a result, the laminated sheet 30 is divided into a plurality of strip-shaped laminated sheets 220. In addition to a guillotine blade with ultrasonic vibration, other methods such as dicing using a dicing blade, a guillotine blade without ultrasonic vibration, laser processing, and scribing can be applied to cut the laminated sheet at this time.

[0175] Next, multiple strip-shaped laminated sheets are placed on a resin substrate made of a first resin having insulating properties.

[0176] Figure 24 is a schematic perspective view showing an example of the structure of a resin substrate. Figure 25A is a schematic perspective view showing an example of a structure in which strip-shaped laminated sheets are arranged on a resin substrate, and Figure 25B is a cross-sectional view taken along line A-A in Figure 25A.

[0177] As shown in Figures 24, 25A, and 25B, the laminated sheets 220, cut into strips, are placed on the resin substrate 510. More specifically, the multiple laminated sheets 220 are placed, for example, in multiple grooves 516 formed in the resin substrate 510 by pick and place. In this case, the laminated sheets 220 are placed in a state in which they can stand upright in the grooves 516. The state in which the laminated sheets 220 can stand upright means that the stacking direction of the first sheet and the second sheet of the laminated sheet 220 is substantially parallel to the depth direction of the groove 516.

[0178] Note that the arrangement method is not limited to pick and place. For example, the following method can also be used. Multiple laminated sheets 220 are placed on a stretchable sheet and stretched to match the shape of multiple grooves 516 of the resin substrate 510. In this way, the multiple laminated sheets 220 are arranged at predetermined intervals. While maintaining this state, the multiple laminated sheets 220 are stacked so that they are accommodated in the multiple grooves 516. In this way, the multiple laminated sheets 220 can be easily arranged in relation to the grooves 516.

[0179] The structure of the resin substrate 510 described above will now be explained in more detail. The resin substrate 510 is made of an insulating resin. As shown in Figure 24, the resin substrate 510 has a bottom surface 511, side surfaces 512, 513, 514, 515, a plurality of grooves 516, and a plurality of partitions 517. Side surfaces 512 and 514 are parallel, and side surfaces 513 and 515 are parallel. Side surfaces 512, 514 and side surfaces 513, 515 are perpendicular. The plurality of grooves 516 are formed by the bottom surface 511, side surfaces 512, 513, 514, 515, and the plurality of partitions 517.

[0180] In the example shown in Figure 24, the multiple grooves 516 are formed parallel to the side portions 512 and 514 and at predetermined intervals. In other words, the multiple grooves 516 are formed at predetermined intervals by the side portions 512, 513, 514, and 515, each having a predetermined thickness, and the multiple partition portions 517. This predetermined interval corresponds to the width of the partition portions 517. In this case, it is preferable that the multiple grooves 516 are formed at approximately equal intervals. This approximately equal arrangement includes configurations that are not unintentionally uniform due to manufacturing tolerances, and does not need to be perfectly uniform.

[0181] Multiple laminated sheets 220 are placed in each of the multiple grooves 516 formed in this manner. At this time, the bottom surfaces of the multiple laminated sheets 220 are positioned to abut against the bottom surfaces of the multiple grooves 516.

[0182] A more specific structure for arranging the laminated sheet 220 on the resin substrate 510 will be described using Figures 25A and 25B. Note that the line A-A in Figure 25A is perpendicular to the direction of the long side of the groove 516 formed in the resin substrate 510.

[0183] As shown in Figures 25A and 25B, the multiple laminated sheets 220 are arranged in the multiple grooves 516. As shown in Figure 24B, it is preferable that the laminated sheets 220 are arranged approximately in the center of the grooves 516 along a direction perpendicular to the line A-A in Figure 25A.

[0184] Next, based on the structure in which the laminated sheets are arranged in Figures 25A and 25B, a more preferable structure for the resin substrate 510 will be described.

[0185] As shown in Figure 25B, the width D1 of the multiple grooves 516 parallel to the A-A line of the resin substrate 510 is greater than the width 220D of the laminated sheet 220. In other words, it is preferable to allow some play so that the width D1 of the grooves 516 is greater than the width 220D of the laminated sheet 220. With such a configuration, it becomes possible to arrange the laminated sheet 220 more efficiently in the grooves 516 than if the width D1 of the grooves 516 and the width 220D of the laminated sheet 220 were approximately the same. In this case, by bringing the width D1 of the grooves 516 closer to the width 220D of the laminated sheet, it becomes possible to arrange the laminated sheet 220 with greater precision in the grooves 516.

[0186] Furthermore, the height (depth) H of the groove 516 in the resin substrate 510 can be determined arbitrarily. In this case, the height H of the groove 516 should be such that it prevents the laminated sheet 220 from tipping over when it is placed in the groove 516. Note that this height H may be the same as the height of the side portions 512, 513, 514, and 515, or it may be smaller than the height of the side portions 512, 513, 514, and 515.

[0187] Furthermore, adjacent grooves 516 are formed with a gap D2 between them by a partition 517. The width (gap D2) of this partition 517 should be determined according to the size of the solid electrolytic capacitor.

[0188] Next, the first and second sides of the strip-shaped laminated sheet are covered with an insulating second resin, and the first through-hole and the third through-hole, and the second through-hole and the fourth through-hole are filled with the second resin, thereby sealing the strip-shaped laminated sheet.

[0189] Figure 26 is a schematic cross-sectional view showing an example of a sealed state of a strip-shaped laminated sheet. Note that, similar to Figure 25B, Figure 26 is a cross-sectional view taken along line A-A in Figure 25A.

[0190] As shown in Figure 26, the strip-shaped laminated sheet 220 placed on the resin substrate 510 is sealed with insulating resin 520 so as to cover it. In this way, the top and sides of the laminated sheet 220 are sealed with insulating resin 520.

[0191] Then, the strip-shaped laminated sheet sealed with the first resin and the second resin is cut at the first and second ends of each element region, and also at the first and second sides of each element region, thereby obtaining an element laminate.

[0192] Figure 27A is a schematic perspective view showing an example of a state in which a strip-shaped laminated sheet is sealed with an insulating resin, and Figure 27B is a schematic perspective view showing an example of a state in which the laminated sheet is divided into individual pieces.

[0193] As shown in Figure 27A, the strip-shaped laminated sheet 220 is sealed with an insulating resin 530 (resin substrate 510 and insulating resin 520).

[0194] The laminated sheet 220, sealed with insulating resin 530, is divided into individual pieces along cutting lines S121 and E121 using a dicing blade (see Figure 27B). This yields the element laminate 100 shown in Figure 11A. In this case, if cutting line E121 is parallel to line A-A in Figure 25A, cutting line S121 is defined between adjacent grooves 516 of the resin substrate 510, in other words, on the partition 517. More specifically, it is preferable that cutting line S121 is defined at approximately the center of the partition 517.

[0195] The laminated sheet, filled with insulating resin in this manner, is separated into individual pieces in a single process.

[0196] The subsequent steps are the same as in the first embodiment. A solid electrolytic capacitor is obtained as a result. In the method for manufacturing a solid electrolytic capacitor according to the fifth embodiment of the present invention, a solid electrolytic capacitor with excellent corrosion resistance can be manufactured, similar to the first embodiment.

[0197] The solid electrolytic capacitor obtained by the manufacturing method described above is also one of the present inventions.

[0198] (Compositional Analysis) Here, we will explain the results of observation and compositional analysis of the laser-processed and unprocessed portions of an aluminum plate, which were formed by laser processing.

[0199] Figure 28 is a schematic plan view of the aluminum plate used for observation and compositional analysis by SEM-EDX. As shown in Figure 28, a through hole H60 was formed in an aluminum plate (thickness = 0.1 mm, manufactured by Nikola) 60 by laser processing. An IR laser was used for laser processing, with a frequency of 1 MHz. The laser-processed aluminum plate 60 was then cut with scissors along the dashed line in Figure 28. A simplified quantitative analysis using the ZAF correction method was then performed on three points each of the wall portion of the through hole H60, i.e., the laser-processed portion, and the cut surface by scissors, i.e., the unprocessed portion. The results are shown in Table 1 below.

[0200]

[0201] As shown in Table 1, it was confirmed that an oxide film is formed by laser processing.

[0202] (Other Embodiments) The method for manufacturing a solid electrolytic capacitor and the solid electrolytic capacitor of the present invention are not limited to the embodiments described above, and various applications and modifications can be made within the scope of the present invention with respect to the configuration, manufacturing conditions, etc., of the solid electrolytic capacitor.

[0203] 1, 1A, 1B Solid electrolytic capacitor 2 Oxide film 10 First sheet 11 Valve-acting metal substrate 12 Porous portion 13 Solid electrolyte layer 14 Mask layer 20 Second sheet 21 Metal foil 30 Laminated sheet 40, 40a, 40b Laminated block 60 Aluminum plate 100, 100A, 100B Element laminate 110 First layer 120 Second layer 131 First sealing portion 132 Second sealing portion 133 Third sealing portion 134 Fourth sealing portion 141 First external electrode 142 Second external electrode R11 First element region of the first sheet R12 Second element region of the first sheet R21 First element region of the second sheet R22 Second element region of the second sheet E3 Third end face of the valve-acting metal substrate E4 Fourth end face of the valve-acting metal substrate E5 Fifth end face of the metal foil E6 Sixth end face of the metal foil E11 First end of the element region of the first sheet E12 Second end of the element region of the first sheet E21 First end of the element region of the second sheet E22 Second end of the element region of the second sheet E101 First end face of the element stack E102 Second end face of the element stack S3 Third side S4 Fourth side S5 Fifth side S6 Sixth side S11 First side of the element region of the first sheet S12 Second side of the element region of the first sheet S21 First side of the element region of the second sheet S22 Second side of the element region of the second sheet S101 First side of the element stack S102 Second side of the element stack M31 First main surface of the laminated sheet M32 Second main surface of the laminated sheet M101 First main surface of the element laminate M102 Second main surface of the element laminate H1 First through hole H2 Second through hole H3 Third through hole H4 Fourth through hole H60 Through hole G Gap in the laminated block

Claims

1. A method for manufacturing a solid electrolytic capacitor comprising the following steps: (A) Step of preparing a first sheet; The first sheet comprises a valve-acting metal substrate having a porous portion on its surface, a dielectric layer formed on the surface of the porous portion, and a solid electrolyte layer provided on the dielectric layer, and further, the first sheet has a plurality of element regions, each element region being demarcated by a first end and a second end opposite to each other in the length direction, and a first side and a second side opposite to each other in the width direction, and further, the first sheet has a first through hole formed so as to straddle the first end of each element region and having a width greater than or equal to the width of the element region, and one or more second through holes formed so as to straddle the second end of each element region and having a width less than the width of the element region, (B) Step of preparing a second sheet; The second sheet is made of metal foil, Furthermore, the second sheet has a plurality of element regions, each element region is demarcated by a first end and a second end facing each other in the length direction, and a first side and a second side facing each other in the width direction, and furthermore, the second sheet has one or more third through holes formed thereon that straddle the first end of each element region and have a width smaller than the width of the element region, and a fourth through hole formed thereon that straddles the second end of each element region and has a width greater than or equal to the width of the element region, (C) Step of manufacturing a laminated sheet; (C) Step in which the first sheet and the second sheet are laminated such that the first ends of each element region and the second ends of each element region face each other, and furthermore, in the laminated sheet, the first through hole and the third through hole, and the second through hole and the fourth through hole are in communication in the lamination direction, (D) Step of manufacturing a laminated block body as necessary; (D) In ​​step (D), a sealing material is filled into the first through hole and the third through hole, and the second through hole and the fourth through hole, respectively, from at least one of the first and second main surfaces of the laminated sheet that are opposite each other in the lamination direction; (E) A step of manufacturing a plurality of element laminates by cutting the laminated sheet or the laminated block;(F) A step of forming a first external electrode and a second external electrode on the element stack; (A) A step of preparing a first sheet, comprising the step of forming a first through hole and a second through hole in the first sheet; (B) A step of preparing a second sheet, comprising the step of forming a third through hole and a fourth through hole in the second sheet; (A) A step of preparing a first sheet and (B) A step of preparing a second sheet, wherein at least one of the first through hole, the second through hole, the third through hole and the fourth through hole is formed by laser processing; In the laser processing, the sheet is cut while irradiating it with a laser and oxidizing the area around the laser-irradiated part.

2. (A) The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein in the step of preparing the first sheet, at least one of the first through hole and the second through hole is formed by the laser processing.

3. (A) The method for manufacturing a solid electrolytic capacitor according to claim 2, wherein in the step of preparing the first sheet, the first through hole and the second through hole are formed by the laser processing.

4. (B) A method for manufacturing a solid electrolytic capacitor according to any one of claims 1 to 3, wherein in the step of preparing the second sheet, at least one of the third through hole and the fourth through hole is formed by the laser processing.

5. (B) The method for manufacturing a solid electrolytic capacitor according to claim 4, wherein in the step of preparing the second sheet, the third through hole and the fourth through hole are formed by the laser processing.

6. The method for manufacturing a solid electrolytic capacitor according to any one of claims 1 to 5, wherein the second sheet is made of aluminum foil or copper foil.

7. A solid electrolytic capacitor comprising an element stack, a first external electrode, and a second external electrode, wherein the element stack comprises a first layer and a second layer, the first layer comprises a valve-acting metal substrate having a porous portion on its surface, a dielectric layer formed on the surface of the porous portion, and a solid electrolyte layer provided on the dielectric layer, the second layer is made of metal foil, further comprising the first end face and the second end face of the element stack, the metal foil and the first sealing portion being exposed on the first end face and the valve-acting metal substrate and the second sealing portion being exposed on the second end face, the first external electrode being provided on the first end face of the element stack and connected to the metal foil, and the second external electrode being provided on the second end face of the element stack and connected to the valve-acting metal substrate. The valve-acting metal substrate has a third end face located on the first end face side and covered by the first sealing portion, and a fourth end face located on the second end face side and facing the second sealing portion, and the metal foil has a fifth end face located on the first end face side and facing the first sealing portion, and a sixth end face located on the second end face side and covered by the second sealing portion, and an oxide film is formed on at least one of the third end face, the fourth end face, the fifth end face and the sixth end face, in a solid electrolytic capacitor.

8. The solid electrolytic capacitor according to claim 7, wherein an oxide film is formed on at least one of the third end face and the fourth end face.

9. The solid electrolytic capacitor according to claim 8, wherein an oxide film is formed on the third end face and the fourth end face, respectively.

10. The solid electrolytic capacitor according to any one of claims 7 to 9, wherein an oxide film is formed on at least one of the fifth end face and the sixth end face.

11. The solid electrolytic capacitor according to claim 10, wherein an oxide film is formed on the fifth end face and the sixth end face, respectively.

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