Solid electrolytic capacitor and method for producing solid electrolytic capacitor

Abstract

This solid electrolytic capacitor is provided with a capacitor element, a sealed body, a first base electrode and a second base electrode. The capacitor element comprises a flat film-like main body that contains a valve-acting metal, a dielectric layer that is formed on a negative electrode formation region, and a solid electrolyte layer that is formed on the dielectric layer. In addition, the capacitor element has a positive electrode terminal region on which a solid electrolyte layer is not formed with respect to the main body, and a negative electrode formation region which comprises a solid electrolyte layer. The sealed body is obtained by stacking a plurality of capacitor elements and sealing the capacitor elements with an insulating resin; and the sealed body has a first end face in which end parts of positive electrode terminal regions are exposed in lines. The first base electrode is arranged on the first end face and contains a first element. The second base electrode covers the first base electrode and contains the first element and a second element. The second base electrode is an intermetallic compound of the first element and the second element.

Description

Solid electrolytic capacitor and method for manufacturing the solid electrolytic capacitor

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

[0002] Patent Document 1 describes a solid electrolytic capacitor that includes a capacitor element and a sealing member made of resin that seals the capacitor element, and that forms a sealing body (insulating resin body) by sealing the capacitor element. In this solid electrolytic capacitor, a cathode terminal and an anode terminal are each drawn out from the capacitor element to the outside of the sealing body by a lead frame, and each terminal functions as an external electrode.

[0003] This solid electrolytic capacitor includes a plurality of capacitor elements, each of which includes an electrode foil, a dielectric layer, and a solid electrolyte layer.

[0004] The surface layer of the electrode foil is a porous body. A dielectric layer is formed on the surface of the porous body. A solid electrolyte layer is formed on the surface of the electrode foil in the area where the dielectric layer is formed.

[0005] International Publication No. 2020 / 179170

[0006] The lead frame in the solid electrolytic capacitor described in Patent Document 1 is formed internally. This lead frame is embedded in an insulating resin body, with portions exposed from both end faces of the insulating resin body and extending across both end faces and the bottom surface. The lead frame on the side embedded in the insulating resin body is welded to the capacitor element. That is, this welded portion becomes a weld margin and functions as an electrode of the solid electrolytic capacitor.

[0007] However, the presence of this weld margin reduces the functional volume ratio of the solid electrolytic capacitor. On the other hand, if the weld margin area is reduced, the capacitor element and the lead frame cannot be reliably connected, which may result in poor contact. Furthermore, even if the capacitor element is enlarged to increase the functional volume ratio, the chip size of the solid electrolytic capacitor increases accordingly.

[0008] The functional part volume ratio in the present invention is defined as follows. The functional part volume ratio is the ratio of the volume of the part that functions as a capacitor to the volume of the solid electrolytic capacitor. In other words, by increasing the functional part volume ratio, a larger capacitance can be achieved for a given external shape size of the solid electrolytic capacitor.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a solid electrolytic capacitor that has an improved functional portion volume ratio and high reliability.

[0010] The solid electrolytic capacitor of the present invention includes a capacitor element, a sealing body, a first base electrode, and a second base electrode. The capacitor element has a flat film-like main body containing a valve metal, a dielectric layer formed on a cathode formation region, and a solid electrolyte layer formed on the dielectric layer. The capacitor element also has an anode terminal region where the solid electrolyte layer is not formed on the main body, and a cathode formation region including the solid electrolyte layer. The sealing body is formed by stacking multiple capacitor elements and sealing them with an insulating resin, and has a first end surface from which the end of the anode terminal region is linearly exposed. The first base electrode is disposed on the first end surface and contains a first element. The second base electrode covers the first base electrode and contains the first element and a second element. The second base electrode is an intermetallic compound of the first element and the second element.

[0011] In this configuration, a laminated capacitor can be formed by forming a first base electrode and a second base electrode on the first end face and welding multiple capacitor elements together. This eliminates the need for welding margins to connect the capacitor elements to the lead frame, allowing for larger areas to be formed on the capacitor elements for the dielectric layer and solid electrolyte layer. This allows for an improved functional volume ratio without increasing the size of the solid electrolytic capacitor.

[0012] A method for manufacturing a solid electrolytic capacitor according to the present invention includes a capacitor element forming step, a sealing body forming step, a first base electrode forming step, a third base electrode forming step, and a first terminal electrode forming step. In the capacitor element forming step, a capacitor element is formed, which includes a flat film-like main body containing a valve metal, a dielectric layer formed on a cathode formation region, and a solid electrolyte layer formed on the dielectric layer, and which has an anode terminal region where the solid electrolyte layer is not formed on the main body, and a cathode formation region including the solid electrolyte layer. In the sealing body forming step, a sealing body is formed by stacking multiple capacitor elements and sealing them with an insulating resin, the sealing body having a first end face from which the end of the anode terminal region is linearly exposed. In the first base electrode forming step, a first base electrode is formed on the first end face and contains a first element. In the third base electrode forming step, a third base electrode is formed containing a second element and covering at least a portion of the first base electrode. In the first terminal electrode forming step, a first terminal electrode is formed containing the second element and covering at least a portion of the third base electrode.

[0013] By pressing the first terminal electrode against the first end surface on which the third base electrode is formed while heating it, the first base electrode and the third base electrode are reacted with each other, and the first terminal electrode and the third base electrode are reacted with each other to form a second base electrode containing the first element and the second element.

[0014] This manufacturing method eliminates the need for a welding allowance for connecting the capacitor element and the lead frame, allowing for a larger area for forming the dielectric layer and solid electrolyte layer in the capacitor element. Furthermore, by forming the second base electrode through a reaction between the first base electrode and the third base electrode, and between the first terminal electrode and the third base electrode, the capacitor element and the lead frame can be reliably connected without the need for a welding process for connecting the capacitor element and the lead frame.

[0015] According to the present invention, it is possible to provide a solid electrolytic capacitor that has an improved functional portion volume ratio and high reliability.

[0016] FIG. 1 is a side cross-sectional view of a solid electrolytic capacitor according to the first embodiment. FIG. 2(A) is a partially enlarged view of a capacitor element according to the first embodiment, and FIG. 2(B) is a side cross-sectional view of the capacitor element. FIG. 3 is a side cross-sectional view and a partially enlarged view of the solid electrolytic capacitor according to the first embodiment. FIGS. 4(A), 4(B), and 4(C) are diagrams specifically illustrating the configuration of the electrode portion. FIG. 5 is a flowchart showing the procedure for forming the solid electrolytic capacitor according to the first embodiment. FIGS. 6(A), 6(B), and 6(C) are diagrams illustrating an outline of forming the solid electrolytic capacitor according to the first embodiment. FIG. 7 is a diagram illustrating an outline of forming electrodes on the capacitor element according to the first embodiment by the AD method. FIG. 8(A) is a side cross-sectional view of a solid electrolytic capacitor according to the present invention, and FIG. 8(B) is a side cross-sectional view of a solid electrolytic capacitor having a conventional configuration.

[0017] [First Embodiment] A solid electrolytic capacitor according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a side cross-sectional view of the solid electrolytic capacitor according to the first embodiment. Fig. 2(A) is a perspective view of a capacitor element according to the first embodiment, and Fig. 2(B) is a side cross-sectional view of the capacitor element. Fig. 3 is a side cross-sectional view of the solid electrolytic capacitor according to the first embodiment, showing an enlarged portion.

[0018] (Structure of Solid Electrolytic Capacitor) The solid electrolytic capacitor 1 includes a capacitor assembly 10, a first terminal electrode 20, a second terminal electrode 30, an insulating resin body 40, and an electrode portion 60. The first terminal electrode 20 and the second terminal electrode 30 correspond to the "external electrodes" of the present invention.

[0019] The capacitor assembly 10 includes a plurality of capacitor elements 11 and a conductive member 19. The conductive member 19 is preferably an electrode paste containing, for example, nickel, silver, or copper as a main component. The maximum thickness of the conductive member 19 is preferably 2 μm or more and 20 μm or less. Note that the conductive member 19 can be omitted if a desired level of conductivity can be obtained between the plurality of capacitor elements 11 and the second terminal electrode 30, for example, without using the conductive member 19.

[0020] In this embodiment, there is no limitation on the number of capacitor elements 11 that make up the capacitor assembly 10, as long as there are a plurality of capacitor elements 11. Details of the capacitor elements 11 will be described later.

[0021] The plurality of capacitor elements 11 are stacked. By stacking the plurality of capacitor elements 11, the capacitor assembly 10 is formed. At this time, the plurality of capacitor elements 11 are formed so as to be approximately parallel to each other.

[0022] The capacitor assembly 10 is sealed with an insulating resin body 40. This forms a sealing body 400. The sealing body 400 has a substantially rectangular parallelepiped shape having a top surface 401, a bottom surface 402, a first end surface 403, and a second end surface 404. The insulating resin body 40 corresponds to the "sealing member" of the present invention.

[0023] At this time, some of the plurality of capacitor elements 11 are exposed from the first end surface 403 of the sealing body 400. The surfaces (first end surfaces 403) where the plurality of capacitor elements 11 are linearly exposed from the insulating resin body 40 are connected to the first terminal electrodes 20 via the electrode portions 60.

[0024] The first terminal electrode 20 is formed along the sealing body 400. Specifically, the first terminal electrode 20 is disposed across the first end surface 403 and the bottom surface 402 of the sealing body 400.

[0025] The connection layers (conductive layers including the solid electrolyte layer 113) of the plurality of capacitor elements 11 are electrically and physically connected to the second terminal electrode 30 by the conductive member 19. The conductive member 19 is formed so as to be exposed from the sealing body 400.

[0026] Similar to the first terminal electrode 20, the second terminal electrode 30 is formed along the sealing body 400. Specifically, the second terminal electrode 30 is disposed across the second end surface 404 and the bottom surface 402.

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

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

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

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

[0031] The capacitor element 11 includes an electrode foil 111 , a dielectric layer 112 , and a solid electrolyte layer 113 .

[0032] The electrode foil 111 is made of, for example, a metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, or silicon, or an alloy containing these metals. The surface layer of the electrode foil 111 is preferably porous. The electrode foil 111 is preferably made of aluminum or an aluminum alloy. The electrode foil 111 may be made of any valve metal that exhibits so-called valve action.

[0033] A dielectric layer 112 is formed on the electrode foil 111. As shown in FIG. 2B , the electrode foil 111 has a first surface F1 and a second surface F2 that face each other in the Z-axis direction. The electrode foil 111 further includes a third surface F3, a fourth surface F4, a fifth surface F5, and a sixth surface F6 that are connected to the first surface F1 and the second surface F2 and parallel to the Z-axis direction. The third surface F3 and the fourth surface F4 are parallel to the Y-axis direction. The fifth surface F5 and the sixth surface F6 are parallel to the X-axis. The dielectric layer 112 covers the first surface F1, the second surface F2, the fourth surface F4, the fifth surface F5, and the sixth surface F6 of the electrode foil 111. An electrode portion 60 is formed on the third surface F3. The third surface F3 forms part of the first end surface 403. The structure of the electrode portion 60 will be described later.

[0034] The dielectric layer 112 is preferably made of an oxide film of the electrode foil 111. For example, when an aluminum foil is used for the electrode foil 111, the dielectric layer 112 is formed by oxidizing the electrode foil 111 in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or a sodium salt or ammonium salt thereof. The thickness of the dielectric layer 112 is preferably 10 nm or more and 100 nm or less.

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

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

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

[0038] The outer layer is a layer formed on the outside of the inner layer. For example, the outer layer is a layer formed so as to cover the entire inner layer after the inner layer is formed to fill the fine recesses of the porous portion. The thickness of the outer layer is preferably 2 μm or more and 20 μm or less. The outer layer is preferably a carbon layer, a graphene layer, or a silver layer formed by applying a conductive paste such as carbon paste, graphene paste, or silver paste. The outer layer may be a composite layer in which a silver layer is provided on a carbon layer or a graphene layer, or a mixed layer in which a carbon paste or a graphene paste is mixed with a silver paste.

[0039] A conductive adhesive layer may be provided as a layer next to the outer layer. The conductive adhesive layer may be made of a material such as a mixture of insulating resin such as epoxy resin or phenolic resin and conductive particles such as carbon or silver.

[0040] With this configuration, capacitor element 11 becomes a flat-film solid electrolytic capacitor. In this capacitor element 11, electrode foil 111 corresponds to the anode, and solid electrolyte layer 113 corresponds to the cathode. The region of electrode foil 111 where solid electrolyte layer 113 is not formed corresponds to the "anode terminal region" in the present invention, and solid electrolyte layer 113 corresponds to the "cathode-forming region" in the present invention. Electrode foil 111 corresponds to the "main body" in the present invention.

[0041] (Structure of Electrode Portion) Next, the structure of the electrode portion 60 formed on the third surface F3 will be described in detail with reference to Fig. 3, Fig. 4(A), Fig. 4(B), and Fig. 4(C). As shown in Fig. 3, the electrode portion 60 includes a first base electrode 61 and a second base electrode 62.

[0042] The first base electrode 61 is formed on the third surface F3 (the end surface of the electrode foil 111) of the capacitor element 11. The first base electrode 61 is formed to a predetermined thickness (height) from the third surface F3. The first base electrode 61 is a Cu layer formed on the third surface F3 using the AD method.

[0043] The second base electrode 62 covers at least the first base electrode 61. As a result, the first base electrode 61 and the second base electrode 62 protrude outward from the third face F3. The first terminal electrode 20 is formed so as to abut against the second base electrode 62.

[0044] 4A, 4B, and 4C, the first terminal electrode 20 is connected to the electrode portion 60. A more specific configuration will be described.

[0045] First, as shown in FIG. 4A , a Cu layer is formed on the third surface F3 of the capacitor element 11 using the AD method. This Cu layer becomes the first base electrode 61. Next, a third base electrode 63 is formed on the first base electrode 61 using the AD method. The third base electrode 63 is a Sn layer. Note that the "first element" in the present invention is Cu that constitutes the first base electrode 61, and the "second element" is Sn that constitutes the third base electrode 63.

[0046] Next, as shown in Fig. 4B, the first terminal electrode 20 is formed so as to abut against the third base electrode 63. The first terminal electrode 20 is pressed against the third surface F3 on which the third base electrode 63 is formed while being heated. As a result, heat is transferred to the first base electrode 61 (Cu) and the third base electrode 63, and the first base electrode 61 (Cu) and the third base electrode 63 (Sn) melt. That is, the Cu layer of the first base electrode 61 reacts with the third base electrode 63, and the Cu ３ An intermetallic compound layer of Sn is formed. ３ The Sn intermetallic compound layer is the second base electrode 62 .

[0047] Similarly, as shown in FIG. 4C, the first terminal electrode 20 reacts with the third base electrode 63. As described above, the first terminal electrode 20 is made of a Cu alloy. That is, the third base electrode 63 reacts with the first terminal electrode 20 and forms a second base electrode 62 (Cu ３ In other words, the third base electrode 63 corrodes the first terminal electrode 20, forming a layer of the second base electrode 62 (Cu ３ The layer is an intermetallic compound layer of Sn.

[0048] This provides a strong bond between the first base electrode 61, the second base electrode 62, and the first terminal electrode 20. The specific method of forming the electrode portion 60 and its specific shape will be described later.

[0049] 3, 4B, and 4C show an example in which the third base electrode 63 reacts with a part of the first base electrode 61 to form the second base electrode 62. However, the third base electrode 63 may remain inside the second base electrode 62. Furthermore, the third base electrode 63 may remain so as to cover at least a part of the second base electrode 62 (between the second base electrode 62 and the first terminal electrode 20).

[0050] The solid electrolytic capacitor 1 is realized by the above configuration.

[0051] (Method for Manufacturing Solid Electrolytic Capacitor) The solid electrolytic capacitor 1 having the above-described configuration is manufactured, for example, as follows. FIG. 5 is a flowchart showing an example of a general flow of the method for manufacturing the solid electrolytic capacitor according to this embodiment. FIGS. 6(A), 6(B), and 6(C) are diagrams showing the state of the solid electrolytic capacitor according to this embodiment at each step. FIG. 7 is a diagram of an apparatus for forming a base electrode using the AD method.

[0052] The capacitor element 11 is formed (S11). Specifically, as shown in Figures 2(A), 2(B), and 6(A), a dielectric layer 112 and a solid electrolyte layer 113 are formed on a plurality of electrode foils 111.

[0053] Next, conductive member 19 is formed on solid electrolyte layer 113 of capacitor element 11. Furthermore, capacitor elements 11 are stacked to form capacitor assembly 10 (S12).

[0054] The capacitor assembly 10 is sealed with an insulating resin body 40 (S13). Specifically, as shown in Fig. 6B, a plurality of capacitor assemblies 10 are stacked, and the capacitor assemblies 10 are sealed with an insulating resin body 40 to form a sealed body 400.

[0055] Next, first end surface 403 (electrode foil 111) of capacitor element 11 is exposed (S14). More specifically, as shown in Fig. 6(C), sealing body 400 is fixed, and electrode foil 111 on first end surface 403 is ground so as to be exposed linearly.

[0056] Similarly, second end face 404 (solid electrolyte layer 113) of capacitor element 11 is exposed (S15). Note that if sealing body 400 is formed so that solid electrolyte layer 113 is exposed, step S15 can be omitted.

[0057] Next, the first base electrode 61 is formed on the electrode foil 111 exposed in step S12 (S16).

[0058] More specifically, as shown in FIG. 7 , the sealed body 400 with the plurality of exposed capacitor elements 11 is fixed on a stage 92 and placed in a chamber 91. At least the tip (ejection end) of an aerosol generator 93 is inserted into the chamber 91. The aerosol generator 93 generates an aerosol by introducing copper powder (Cu powder) 610 into a carrier gas, and sprays the aerosol onto the first end surface 403 of the sealed body 400. By appropriately setting the aerosol specifications (e.g., the volume ratio of copper powder 610 contained in the carrier gas) and spraying conditions (e.g., the number of sprays, the spraying strength, etc.), the copper powder 610 is piled up to a predetermined height (predetermined thickness) mainly on the third surface F3 of the plurality of electrode foils 111, thereby forming the first base electrode 61. The particle size of the copper powder 610 is, for example, approximately 3 μm, but may be 2 μm or less.

[0059] Next, a third base electrode 63 is formed on the first base electrode 61 formed in step S16 using the AD method (S17).

[0060] More specifically, as shown in FIG. 7 , the sealing body 400 on which the first base electrode 61 is formed is fixed on a stage 92 and placed in a chamber 91. At least the tip (ejection tip) of an aerosol generator 93 is inserted into the chamber 91. The aerosol generator 93 generates an aerosol by introducing Sn powder into a carrier gas, and sprays the aerosol onto the first end surface 403 of the sealing body 400 and the first base electrode 61. At this time, by appropriately setting the aerosol specifications (e.g., the volume ratio of the Sn powder 620 contained in the carrier gas) and the spraying conditions (e.g., the number of sprays, the spraying strength, etc.), the Sn powder 620 is piled up to a predetermined height (predetermined thickness) mainly on the third surfaces F3 of the multiple electrode foils 111 and the first base electrode 61, thereby forming the third base electrode 63.

[0061] Next, the first terminal electrode 20 is formed on the first end surface 403, and the second terminal electrode 30 is formed on the second end surface 404, thereby forming a lead frame (LF) for the solid electrolytic capacitor 1 (S18). More specifically, the first terminal electrode 20 and the second terminal electrode 30 are brought into contact with the sealing body 400, and heated and pressurized.

[0062] As described above, the first base electrode 61 and the third base electrode 63 are formed to have irregularities using the AD method (see FIG. 4A). That is, the first base electrode 61 and the third base electrode 63 are bonded more firmly by the anchor effect. As shown in FIGS. 3, 4A, 4B, and 4C, when heat is applied to the first terminal electrode 20, the heat is applied to the first base electrode 61 and the third base electrode 63, and an intermetallic compound (Cu ３ Sn) is formed. ３ The electrode foil 111 and the first terminal electrode 20 are electrically and physically connected to each other through the first and second base electrodes 61 and 62. In particular, the formation of an intermetallic compound improves the bonding strength. Similarly, the second terminal electrode 30 is connected to the capacitor element 11 via the conductive member 19.

[0063] If the width of the lead frame is narrower than the width of the sealing body 400, a sealing resin may be applied to the portions of each end surface of the sealing body 400 that are not covered by the lead frame to prevent moisture from entering the interior of the sealing body 400. As shown in the enlarged view of FIG. 3 , there is a small gap between the porous portion (surface layer) of the electrode foil 111 and the lead frame, and this gap may also serve as a route for moisture to enter. To block such a route for moisture to enter, a sealing resin may be applied to the portions of each end surface of the sealing body 400 that are not covered by the lead frame, even if the width of the lead frame is not narrower than the width of the sealing body 400. These measures can improve the moisture resistance of the solid electrolytic capacitor 1.

[0064] Next, using FIGS. 8A and 8B, a comparison will be made between the solid electrolytic capacitor 1 formed using the above-described configuration and a solid electrolytic capacitor 1A having a conventional configuration.

[0065] Fig. 8A is a side cross-sectional view of a solid electrolytic capacitor 1 having a configuration according to the present invention, and Fig. 8B is a side cross-sectional view of a solid electrolytic capacitor 1A having a conventional configuration.

[0066] 8A and 8B, the functional part volume ratio in the configuration of the present invention is about 1.5 times that of the conventional configuration. More specifically, in Fig. 8A, the first terminal electrode 20 is not formed inside the solid electrolytic capacitor 1, so the functional part volume ratio can be made large. On the other hand, since the external shape of the solid electrolytic capacitor 1 is the same as that of the solid electrolytic capacitor 1A, the volume of the solid electrolytic capacitor 1 is the same as that of the solid electrolytic capacitor 1A.

[0067] That is, the functional part volume ratio of the portion that actually functions as a capacitor can be increased compared to the conventional configuration without increasing the size of the solid electrolytic capacitor 1. Therefore, when the size of the solid electrolytic capacitor 1 having the configuration of the present invention and the size of the solid electrolytic capacitor 1A are the same, the functional part volume ratio of the solid electrolytic capacitor 1 is improved.

[0068] Furthermore, the capacitor element 11 and the first terminal electrode 20 are physically and electrically connected by the electrode portion 60. That is, the connection between the capacitor element 11 and the first terminal electrode 20 can be ensured. In particular, the formation of an intermetallic compound in the electrode portion 60 improves the bonding strength. Therefore, a highly reliable solid electrolytic capacitor 1 can be provided.

[0069] The solid electrolytic capacitor is not limited to the above-described configuration in which a plurality of flat film capacitor elements are stacked in the thickness direction of the solid electrolytic capacitor, but may instead be configured, for example, in which flat film capacitor elements are wound and housed in a cylindrical housing.

[0070] Furthermore, the configurations and various derivative examples shown in the above-described embodiments can be combined as appropriate, and effects corresponding to each combination can be achieved.

[0071] F1...first surface F2...second surface F3...third surface F4...fourth surface F5...fifth surface F6...sixth surface 1, 1A...solid electrolytic capacitor 10...capacitor assembly 11...capacitor element 19...conductive member 20...first terminal electrode 30...second terminal electrode 40...insulating resin body 60...electrode portion 61...first base electrode 62...second base electrode 63...third base electrode 91...chamber 92...stage 93...aerosol generator 111...electrode foil 112...dielectric layer 113...solid electrolyte layer 400...sealing body 401...top surface 402...bottom surface 403...first end surface 404...second end surface 610...copper powder 620...Sn powder

Claims

1. A solid electrolytic capacitor comprising: a capacitor element having a flat film-like body containing a valve metal, a dielectric layer formed on a cathode formation region, and a solid electrolyte layer formed on the dielectric layer, the capacitor element having an anode terminal region where the solid electrolyte layer is not formed on the body, and the cathode formation region including the solid electrolyte layer; a sealing body formed by stacking a plurality of the capacitor elements and encapsulating the sealing body with an insulating resin, the sealing body having a first end face from which an end of the anode terminal region is linearly exposed; a first base electrode disposed on the first end face and containing a first element; and a second base electrode covering the first base electrode and containing the first element and a second element, wherein the second base electrode is an intermetallic compound of the first element and the second element.

2. The solid electrolytic capacitor according to claim 1, further comprising a first terminal electrode covering said second base electrode.

3. The solid electrolytic capacitor according to claim 1, further comprising a third base electrode covering at least a portion of the second base electrode and containing the second element.

4. The solid electrolytic capacitor according to claim 3, further comprising a first terminal electrode covering the second base electrode or the third base electrode.

5. The solid electrolytic capacitor according to claim 2 or 4, wherein the first terminal electrode contains the first element.

6. The solid electrolytic capacitor according to claim 1, wherein the sealing body has a second end surface from which the solid electrolyte layer in the cathode formation region is exposed, and a second terminal electrode is formed on the second end surface.

7. A capacitor element forming process for forming a capacitor element having a flat film-like body containing a valve metal, a dielectric layer formed on a cathode formation region, and a solid electrolyte layer formed on the dielectric layer, the capacitor element having an anode terminal region where the solid electrolyte layer is not formed on the body, and the cathode formation region including the solid electrolyte layer; an encapsulation forming process for stacking a plurality of the capacitor elements and forming an encapsulation body sealed with an insulating resin and having a first end face from which an end of the anode terminal region is linearly exposed; a first base electrode forming process for forming a first base electrode disposed on the first end face and containing a first element; a third base electrode forming process for forming a third base electrode containing a second element and covering at least a portion of the first base electrode; and a first terminal electrode forming process for forming a first terminal electrode containing the second element and covering at least a portion of the third base electrode. a first terminal electrode being pressed against the first end face on which the third base electrode is formed while being heated, thereby causing a reaction between the first base electrode and the third base electrode, and causing a reaction between the first terminal electrode and the third base electrode, thereby forming a second base electrode containing the first element and the second element.

8. The method for manufacturing a solid electrolytic capacitor according to claim 7, further comprising forming a second terminal electrode on a second end surface of the sealing body where the solid electrolyte layer is exposed in the cathode formation region.