Solid electrolytic capacitor element, solid electrolytic capacitor, and manufacturing method of solid electrolytic capacitor

Abstract

To provide a highly reliable solid electrolytic capacitor in which an increase in difficulty during formation is suppressed and a decrease in electrical characteristics is suppressed.SOLUTION: A solid electrolytic capacitor includes a plurality of valve metal substrates, an insulator layer, a solid electrolyte layer, and a conductor layer. The plurality of valve metal bases each have a dielectric layer on at least one main surface and are divided into an anode terminal region and a cathode forming region. The insulator layer is provided so as to have a predetermined thickness in a boundary region between the anode terminal region and the cathode forming region. The solid electrolyte layer is provided on the dielectric layer in the cathode forming region. The conductive layer is provided on the solid electrolyte layer. The stacked plurality of valve metal substrates are bonded using an insulator layer. The plurality of valve metal bases are disposed such that the cathode forming regions are spaced apart from each other in accordance with a predetermined thickness of the insulator layer. The solid electrolyte layer is continuously formed in the cathode forming region of the plurality of valve metal substrates and a part of the insulator layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solid electrolytic capacitor in which a plurality of capacitor elements are stacked. [Background technology]

[0002] Various techniques for stacking multiple capacitor elements to obtain a specified capacitor capacitance have been known. In order to increase the capacitance of a solid electrolytic capacitor, it is necessary to stack more capacitor elements. A solid electrolyte layer, a carbon layer, and a metal layer are formed in the cathode region of each capacitor element. Furthermore, the cathode regions of the multiple capacitor elements are bonded together using an adhesive layer (an adhesive silver layer).

[0003] When product dimensions are specified, the number of layers that can be stacked in a capacitor element is limited by the thicknesses of the solid electrolyte layer, carbon layer, metal layer, and adhesive layer. Furthermore, the thicknesses of the solid electrolyte layer, carbon layer, metal layer, and adhesive layer formed in a capacitor element may vary. This can lead to variations in the electrical characteristics of solid electrolytic capacitors and variations in product dimensions, which can reduce the yield rate of products.

[0004] To solve these problems, Patent Document 1 discloses the configuration of a solid electrolytic capacitor. The solid electrolytic capacitor in Patent Document 1 has a valve metal substrate, multiple metal sheets including a dielectric film formed in the cathode region, and a conductive substrate fixed together using a joint. In this fixed state, an oxide film, a solid electrolyte layer, a carbon layer, and a metal layer are formed on the multiple metal sheets. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-156468 Summary of the Invention [Problem to be solved by the invention]

[0006] The solid electrolytic capacitor in Patent Document 1 is formed as follows. (Step 1) Insulation portions are formed on a plurality of valve metal sheets. (Step 2) A plurality of valve metal sheets with insulating portions formed thereon and conductive substrates are alternately stacked so that the insulating portions abut against each other, thereby forming a laminate. (Step 3) The metal sheets constituting the laminate are joined at predetermined positions (at the insulating spaced portions). (Step 4) The cathode region of the laminate is immersed in an electrolyte to perform an oxide film treatment. (Step 5) A solid electrolyte layer is formed by immersing the cathode region of the laminate in a solution for a solid electrolyte. (Step 6) A carbon layer and a metal layer (silver paste) are formed so as to cover the outer periphery of the solid electrolyte layer. (Step 7) A lead frame (external electrode) is formed. (Step 8) Seal with insulating resin. In this way, since steps 4, 5, and 6 are performed on the laminate that has undergone step 3, errors due to variations in the thickness of the solid electrolyte layer, carbon layer, and metal layer can be reduced. In other words, the solid electrolytic capacitor in Patent Document 1 can easily achieve the desired capacitance.

[0007] However, in step 2, in which multiple metal sheets and conductive substrates are laminated, the thickness, burrs, warping, etc. of the conductive substrate are easily affected. Furthermore, the accuracy of the positions at which the multiple metal sheets and conductive substrates are arranged must be increased. In other words, the difficulty of forming a solid electrolytic capacitor may increase.

[0008] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a highly reliable solid electrolytic capacitor in which the difficulty of manufacturing the capacitor is reduced and the deterioration of electrical characteristics is suppressed. [Means for solving the problem]

[0009] The solid electrolytic capacitor of the present invention comprises a plurality of valve metal substrates, an insulator layer, a solid electrolyte layer, and a conductor layer. The plurality of valve metal substrates have a dielectric layer on at least one main surface and are divided into an anode terminal region and a cathode formation region. The insulator layer is provided to have a predetermined thickness in the boundary region between the anode terminal region and the cathode formation region. The solid electrolyte layer is provided on the dielectric layer in the cathode formation region. The conductor layer is provided on the solid electrolyte layer. The stacked plurality of valve metal substrates are bonded together using an insulator layer. The plurality of valve metal substrates are arranged with their cathode formation regions spaced apart according to the predetermined thickness of the insulator layer. The solid electrolyte layer is formed continuously in the cathode formation regions of the plurality of valve metal substrates and in part of the insulator layer.

[0010] In this configuration, the insulator layer is formed on the plurality of valve metal substrates to a predetermined thickness. Furthermore, because the plurality of valve metal substrates are fixed by the insulator layer, the cathode formation regions of the plurality of valve metal substrates are spaced apart. In other words, by using only the insulator layer, the plurality of valve metal substrates can be fixed so that the cathode formation regions are spaced apart. This makes it easier to form the solid electrolyte layer and the conductor layer. In other words, the difficulty of forming a solid electrolytic capacitor can be reduced. Furthermore, because the solid electrolyte layer and the conductor layer can be easily formed to a uniform thickness, a highly reliable solid electrolytic capacitor can be realized with reduced degradation in electrical characteristics.

[0011] The method for manufacturing a solid electrolytic capacitor of the present invention includes multiple steps, from step 1 to step 7. In step 1, an insulator layer is formed in the boundary region between the anode terminal region and the cathode formation region of a plurality of valve action metal substrates, each having a dielectric layer on at least one main surface and divided into an anode terminal region and a cathode formation region. In step 2, a first laminate is formed by stacking the plurality of valve action metal substrates so that the cathode formation regions are spaced apart at a predetermined interval using the insulator layer. In step 3, a solid electrolyte layer is formed on the dielectric layer in the cathode formation region. In step 4, a conductor layer is formed on the solid electrolyte layer. In step 5, a second laminate is formed, including the first laminate and the solid electrolyte layer and conductor layer formed on the plurality of valve action metal substrates. In step 6, the second laminate is sealed with an insulating resin. In step 7, external electrodes are formed in the anode terminal region and the cathode formation region.

[0012] In this manufacturing method, a first laminate is formed in the second step. At this time, an insulator layer having a predetermined thickness is formed on the plurality of valve metal substrates. Furthermore, because the plurality of valve metal substrates are fixed by the insulator layer, the cathode formation regions of the plurality of valve metal substrates are spaced apart. In other words, by using only the insulator layer, it is possible to fix the plurality of valve metal substrates so that the cathode formation regions are spaced apart. This allows the solid electrolyte layer (third step) and the conductor layer (fourth step) to be formed more uniformly and easily. In other words, the difficulty of forming a solid electrolytic capacitor is prevented from increasing, and a highly reliable solid electrolytic capacitor with reduced degradation in electrical characteristics can be realized. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a highly reliable solid electrolytic capacitor in which the difficulty of formation is suppressed and the deterioration of electrical characteristics is suppressed. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view of the solid electrolytic capacitor according to the first embodiment. [Figure 2]FIG. 2(A) is an enlarged view of a portion of the capacitor element according to the first embodiment, and FIG. 2(B) is a cross-sectional view of the capacitor element. [Figure 3] FIG. 3 is a flowchart showing the procedure for forming the solid electrolytic capacitor according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing a procedure for forming the laminate according to the first embodiment. [Figure 5] 5(A), 5(B), 5(C), and 5(D) are cross-sectional views of the laminate according to the first embodiment. [Figure 6] 6(A) is a cross-sectional view including line AA in FIG. 5(A), and FIG. 6(B) is a cross-sectional view including line BB in FIG. 5(D). [Figure 7] 7(A), 7(B), 7(C), and 7(D) are cross-sectional views of the laminate according to the second embodiment. [Figure 8] 8(A) is a cross-sectional view including line AA in FIG. 7(A), and FIG. 8(B) is a cross-sectional view including line CC in FIG. 7(D). [Figure 9] FIG. 9 is a cross-sectional view of a solid electrolytic capacitor according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0015] [First embodiment] A solid electrolytic capacitor 1 according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view of the solid electrolytic capacitor according to the first embodiment. Fig. 2(A) is an enlarged view of a portion of the capacitor element according to the first embodiment, and Fig. 2(B) is a cross-sectional view of the capacitor element.

[0016] (Structure of solid electrolytic capacitor) The solid electrolytic capacitor 1 includes a laminate 20 (capacitor assembly), a first external electrode 501, a second external electrode 502, and an insulating resin body 40. Note that in FIG. 1, some components are omitted for clarity. Also, some structures are exaggerated. Note that the laminate 20 corresponds to the "second laminate" of the present invention.

[0017] 1, laminate 20 includes a plurality of capacitor elements 11. The plurality of capacitor elements 11 are stacked. The stacking direction of the plurality of capacitor elements 11 in laminate 20 corresponds to the Z-axis direction in FIG.

[0018] In this embodiment, the number of capacitor elements 11 constituting laminate 20 is not limited as long as it is plural. The structure of capacitor element 11 will be described in detail later.

[0019] The laminate 20 is sealed with an insulating resin body 40. This forms a sealed body 400. The sealed body 400 has a generally rectangular parallelepiped shape having a top surface 401, a bottom surface 402, a first surface 403, a second surface 404, and two side surfaces. The first surface 403 is the surface opposite the second surface 404.

[0020] First external electrode 501 is formed along sealing body 400 and part of capacitor element 11. Specifically, first external electrode 501 is disposed on first surface 403 of sealing body 400, part of the side surface of capacitor element 11, and bottom surface 402 of sealing body 400.

[0021] The first external electrode 501 is preferably formed from a metal material that is easy to bend and has high conductivity, such as a copper alloy or iron alloy material. The first external electrode 501 is formed from a material cut out from a metal plate, for example, and has a configuration in which the metal plate is bent at a midpoint in the length direction.

[0022] Second external electrode 502 is formed along sealing body 400. Specifically, second external electrode 502 is disposed across second surface 404 and bottom surface 402. Capacitor element 11 and second external electrode 502 may be joined by a conductive adhesive 50 made of, for example, silver paste.

[0023] In this case, the connection layer of the plurality of capacitor elements 11 (a conductive layer including solid electrolyte layer 113 formed on the outer surface of electrode foil 111 (anode electrode)) is electrically and physically connected to second external electrode 502 by conductive adhesive 50. However, the connection between capacitor element 11 and second external electrode 502 is not limited to this, and the connection layer of capacitor element 11 may be directly connected to second external electrode 502.

[0024] Like the first external electrode 501, the second external electrode 502 is preferably formed from a metal material that is easy to bend and has high conductivity, such as a copper alloy or iron alloy. The second external electrode 502 is formed from a material cut out of a metal plate (metal sheet), for example, and is configured by bending the metal sheet midway along its length. The first external electrode 501 and the second external electrode 502 may be made of the same material or different materials.

[0025] 1, the first external electrode 501 and the second external electrode 502 are formed so as to abut against the end faces of the laminate 20. However, the first external electrode 501 and the second external electrode 502 are not limited to the configuration shown in FIG. 1, and may have the following configuration. The first external electrode 501 and the second external electrode 502 have one end and the other end. A configuration may be adopted in which one end of the first external electrode 501 and one end of the second external electrode 502 are sandwiched in the stacking direction (Z-axis direction) of the multiple capacitor elements 11, and the other ends are arranged so as to abut against the side and bottom surfaces of the laminate 20.

[0026] Furthermore, the first external electrode 501 and the second external electrode 502 may be flexible so as to have a horizontal portion parallel to the bottom surface of the laminate 20. This horizontal portion is arranged so as to abut against the bottom surface of the laminate 20. The horizontal portion and the bottom surface of the laminate 20 are connected. In this case, the horizontal portion and the bottom surface of the laminate 20 are connected by laser welding. This allows the conductive adhesive 50 to be omitted.

[0027] The insulating resin body 40 is mainly made of resin and may contain a filler. Examples of preferred resins include epoxy resin, phenol resin, polyimide resin, silicone resin, polyamide resin, and liquid crystal polymer. The resin may be in either solid or liquid form. It is preferred that corners are rounded by barrel polishing after resin sealing. Examples of preferred fillers include silica particles and alumina particles. The maximum diameter of the filler is preferably 30 μm or more and 40 μm or less. A material containing silica particles in a solid epoxy resin and phenol resin is more preferred.

[0028] (Capacitor element structure) The structure of capacitor element 11 will be described in more detail with reference to Figures 2(A) and 2(B). Figure 2(A) is an enlarged view of a portion of capacitor element 11 according to the first embodiment. Figure 2(B) is a cross-sectional view of capacitor element 11. Note that the structure shown in Figure 2(B) is a schematic diagram illustrating a simplified structure. In reality, the surface of porous layer 111L is enlarged, and this enlarged surface is covered with dielectric layer 112.

[0029] Capacitor element 11 includes electrode foil 111, dielectric layer 112, solid electrolyte layer 113, carbon layer 114, metal layer 115, and insulator layer 116. Electrode foil 111 includes electrode layer 111F and porous layer 111L. Carbon layer 114 and metal layer 115 correspond to the "conductor layer" of the present invention. The conductor layer is not limited to a configuration including both carbon layer 114 and metal layer 115; for example, carbon layer 114 may be omitted.

[0030] A more specific structure of the electrode foil 111 is as follows. The electrode layer 111F is made of, for example, a metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, or silicon, or an alloy containing these metals. The electrode layer 111F is preferably made of aluminum or an aluminum alloy. A porous layer 111L is formed on the surface of the electrode layer 111F. The porous layer 111L is formed by etching the surface of the electrode layer 111F. This makes the porous layer 111L porous. The electrode foil 111 may be any valve metal that exhibits so-called valve action. The electrode foil 111 corresponds to the "valve metal substrate" of the present invention.

[0031] A dielectric layer 112 is formed on the electrode foil 111. As shown in FIGS. 2(A) and 2(B), the electrode foil 111 has a first surface F1 and a second surface F2 that face each other in the Z-axis direction (the stacking direction of the laminate). 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 and the Z-axis direction. The fifth surface F5 and the sixth surface F6 are parallel to the X-axis direction and the Z-axis direction. 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.

[0032] The dielectric layer 112 is preferably made of an oxide film of the electrode foil 111 (porous layer 111L). For example, when an aluminum foil is used for the electrode layer 111F, the dielectric layer 112 is formed by applying a voltage in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or their sodium salts or ammonium salts, and then anodizing the aluminum foil. The thickness of the dielectric layer 112 is preferably 100 nm or less.

[0033] 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.

[0034] More specifically, the solid electrolyte layer 113 includes, for example, an inner layer and an outer layer.

[0035] The inner layer is a layer of solid electrolyte layer 113 that abuts on dielectric layer 112, and may be, for example, a PEDOT:PSS layer realized by a conductive polymer having a skeleton of pyrroles, thiophenes, anilines, or the like, or a conductive polymer having a skeleton of thiophenes such as PEDOT [poly(3,4-ethylenedioxythiophene)], and composited with polystyrene sulfonate (PSS) as a dopant. The inner layer is formed by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of dielectric layer 112 using an electrolyte solution that serves as the base for forming solid electrolyte layer 113, for example, a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or a method of applying a dispersion of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric portion and drying it, or the like.

[0036] The outer layer is a layer formed on the outside of the inner layer. For example, the outer layer is formed so as to cover the entire surface of the inner layer after the inner layer is formed to fill the fine recesses in the porous portion. The thickness of the outer layer is preferably 2 μm or more and 20 μm or less. The outer layer is formed by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of the inner layer using an electrolyte solution that serves as the base for forming the solid electrolyte layer 113, for example, a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or a method of applying a dispersion or paste of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the inner layer portion and drying it, or the like.

[0037] The carbon layer 114 is formed so as to cover the outer layer (solid electrolyte layer 113). The carbon layer 114 contains a thermosetting resin. More specifically, the carbon layer 114 is formed by applying a carbon paste in which an insulating resin such as a phenolic resin is mixed with particles of carbon black or graphite.

[0038] The metal layer 115 is formed so as to cover the carbon layer 114. The metal layer 115 includes a thermoplastic resin. More specifically, the metal layer 115 is formed by applying a metal paste in which an insulating resin such as a phenolic resin is mixed with silver particles, for example.

[0039] With this configuration, capacitor element 11 is 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 is the anode terminal region, and the region where solid electrolyte layer 113 is formed is the cathode formation region.

[0040] Furthermore, an insulator layer 116 is formed on capacitor element 11. More specifically, insulator layer 116 has a first insulator layer 1161 and a second insulator layer 1162. First insulator layer 1161 and second insulator layer 1162 are formed in regions of electrode foil 111 where solid electrolyte layer 113 is not formed. Preferably, insulator layer 116 separates the anode terminal region from the cathode formation region. In other words, insulator layer 116 is preferably formed in the boundary region that separates the anode terminal region from the cathode terminal region.

[0041] First insulator layer 1161 is formed on first face F1, second face F2, fifth face F5, and sixth face F6 of electrode foil 111. In other words, as shown in Fig. 2(B) , first insulator layer 1161 is formed on faces other than third face F3 and fourth face F4 of electrode foil 111 so as to cover part of the outer periphery of electrode foil 111.

[0042] Second insulator layer 1162 is formed so as to cover the first surface F1 side and part of the second surface F2 of first insulator layer 1161. Second insulator layer 1162 may be configured so that part of it covers first insulator layer 1161 and part of it is formed in the anode terminal region of electrode foil 111. In other words, second insulator layer 1162 may be formed so as to straddle first insulator layer 1161 and the anode terminal region.

[0043] The first insulator layer 1161 is made of, for example, polyimide resin. The first insulator layer 1161 contains almost no filler. More specifically, it is desirable that the first insulator layer 1161 penetrates not only the outer surface of the electrode foil but also the porous layer 111L. Therefore, it is desirable that the first insulator layer 1161 has a viscosity sufficient to penetrate the porous layer 111L. Furthermore, if the first insulator layer 1161 contains a filler, there is a possibility that it may clog the porous layer 111L, so it is desirable that there is no filler or that there is only a small amount of filler.

[0044] The second insulator layer 1162 is made of an adhesive resin and contains a filler. The second insulator layer 1162 is, for example, an epoxy resin. The second insulator layer 1162 functions to secure multiple electrode foils. That is, the second insulator layer 1162 as a paste preferably has a viscosity that prevents excessive spreading when pressure is applied to secure the layer, and preferably contains a filler to prevent excessive volume change after drying. After the second insulator layer 1162 as a resin component is applied to a predetermined location, the solvent is removed by drying. The second insulator layer 1162 is then preferably secured by pressure and drying at high temperature, which prevents excessive spreading.

[0045] In the first embodiment, the first insulator layer 1161 and the second insulator layer 1162 are made of resins containing different components. However, the first insulator layer 1161 and the second insulator layer 1162 may be made of resins containing the same components. For example, the first insulator layer 1161 and the second insulator layer 1162 may be made of the same main component resin, and the additives and the like may be adjusted to achieve the difference in characteristics described above.

[0046] (Solid Electrolytic Capacitor Manufacturing Method) The solid electrolytic capacitor 1 having the above-described configuration is manufactured, for example, as follows. FIG. 3 is a flowchart showing the procedure for forming the solid electrolytic capacitor according to the first embodiment. FIG. 4 is a flowchart showing the procedure for forming the laminate according to the first embodiment. FIGS. 5(A), 5(B), 5(C), and 5(D) are cross-sectional views of the laminate according to the first embodiment. FIG. 6(A) is a cross-sectional view taken along line AA passing through the insulator layer 116 in FIG. 5(A), and FIG. 6(B) is a cross-sectional view taken along line BB passing through the cathode formation region in FIG. 5(D).

[0047] First, the procedure for forming the solid electrolytic capacitor 1 will be described.

[0048] 1 is formed (S11). A more specific process for forming the laminate 20 will be described later.

[0049] Next, the end of the anode terminal region of the laminate 20 (electrode foil 111) is joined to the first external electrode 501 (S12). The anode terminal region and the first external electrode 501 are joined by a laser or the like. However, the connection between the end of the anode terminal region of the laminate 20 and the first external electrode 501 is not limited to this. For example, the end of the anode terminal region of the laminate 20 and the first external electrode 501 may be connected by applying a conductive adhesive to the end of the anode terminal region of the laminate 20.

[0050] Next, the end portion (metal layer 115) of the cathode formation region of the laminate 20 is bonded to the second external electrode 502 (S13). More specifically, the second external electrode 502 and the metal layer 115 are bonded to each other with a conductive adhesive 50 such as silver paste. This bonded portion is cured at 200°C.

[0051] Next, the laminate 20 with the first external electrode 501 and the second external electrode 502 joined together is placed in a mold 500 and resin sealing is performed (S14). More specifically, the laminate 20 is sealed with an insulating resin body 40 by transfer molding.

[0052] Next, the first external electrode 501 is bent along the sealing body 400 (S15). More specifically, the first external electrode 501 is bent along the first surface 403 and the bottom surface 402 of the sealing body 400, and heated and pressed.

[0053] Next, the second external electrode 502 is bent along the sealing body 400. More specifically, the second external electrode 502 is bent along the second surface 404 and the bottom surface 402 of the sealing body 400, and heated and pressed (S16).

[0054] (Detailed structure of the capacitor assembly) Next, a method for forming the laminate 20 and a more detailed structure of the capacitor assembly will be described using Figures 4, 5(A), 5(B), 5(C), 5(D), 6(A), and 6(B).

[0055] An anode body is formed by forming a dielectric layer 112 on electrode foil 111 (S111).

[0056] Next, as shown in FIG. 5(A), a first insulator layer 1161 is formed near one end of the anode body (S112).

[0057] 5(A), the second insulator layer 1162 is formed (S113) so as to be in contact with the first insulator layer 1161. As described above, the second insulator layer 1162 is preferably formed at a position that overlaps the first insulator layer 1161 and the anode terminal region when viewed in the Z-axis direction.

[0058] Next, as shown in FIG. 5(A), the region where the insulator layer 116 (first insulator layer 1161 and second insulator layer 1162) is formed is hot-pressed (S114). This connects the stacked anode bodies using the insulator layer 116, and the stacked state can be maintained. The stack formed in this manner becomes the stack 10. The multiple anode bodies in the stack 10 are fixed so as to be approximately parallel to the Z-axis direction, with the insulator layer 116 as the base point. As described above, the anode spacing in the Z-axis direction is formed to be in the range of 20 μm or more and less than 140 μm. The stack 10 corresponds to the "first stack" of the present invention.

[0059] In this case, the spacing between the multiple anode bodies in the Z-axis direction (hereinafter referred to as the anode spacing) can be controlled by the pressure during hot pressing, the bottom dead center, etc. The anode spacing is formed to be in the range of 20 μm or more and less than 140 μm. A more preferable anode spacing is about 60 μm.

[0060] 5(B), a solid electrolyte layer 113 is formed in the cathode formation region of the laminate 10 (S115). Step S115 includes the steps of impregnating the cathode formation region of the laminate 10 (the region formed with the insulator layer 116 as a boundary) with a dispersion of PEDOT:PSS, drying at approximately 150°C, and removing the solvent. These three steps are repeated seven times.

[0061] As a result, solid electrolyte layer 113 made of a conductive polymer is formed in the cathode formation region. Solid electrolyte layer 113 is formed continuously in the cathode formation region and in part of insulator layer 116. Solid electrolyte layer 113 covers the anode body in the cathode formation region and is formed so as to be in contact with first insulator layer 1161 and second insulator layer 1162 that are close to the cathode formation region.

[0062] 5(C), the carbon layer 114 is formed so as to cover the solid electrolyte layer 113 (S116). The carbon layer 114 is formed by impregnating the laminate 10 on which the solid electrolyte layer 113 has been formed in a carbon paste and drying it at 150°C to remove the solvent. At this time, the carbon layer 114 is formed so as to cover the solid electrolyte layer 113 and to expose the end portions of the solid electrolyte layer 113.

[0063] 5(D), a metal layer 115 is formed so as to cover the carbon layer 114 (S117). The metal layer 115 is formed by impregnating the laminate 10, on which the solid electrolyte layer 113 and the carbon layer 114 have been formed, in silver paste and drying it at 200°C to remove the solvent. The metal layer 115 is formed so as to cover the carbon layer 114 and expose the ends of the carbon layer 114.

[0064] These steps make it possible to easily form a plurality of capacitor elements 11, each having an electrode foil 111, a dielectric layer 112, a solid electrolyte layer 113, a carbon layer 114, and a metal layer 115 stacked one on top of the other, and a laminate 20. Furthermore, because the anode bodies are arranged at predetermined intervals (anode intervals) by the insulator layers 116, it is possible to form capacitor elements with uniform and precise thicknesses simply by impregnating the laminate 10 in a predetermined solution. Furthermore, because the anode bodies are fixed using only the insulator layers 116, the structure is extremely simple. In this embodiment, there is no need to use a separate conductive substrate between the plurality of capacitor elements 11, which reduces costs and omits the step of forming (sandwiching) a conductive substrate.

[0065] As described above, if carbon layer 114 can be omitted, step S116 may be omitted, and after solid electrolyte layer 113 is formed in step S115, metal layer 115 may be formed immediately in step S117.

[0066] Fig. 6(A) is a cross-sectional view of a plane (YZ plane) including line AA parallel to the Z-axis direction in Fig. 5(A). This YZ plane is a plane passing through insulator layer 116. At approximately the center in the Y-axis direction in Fig. 6(A), a first insulator layer 1161, a dielectric layer 112, an electrode foil 111, a dielectric layer 112, a first insulator layer 1161, and a second insulator layer 1162 are repeatedly stacked in this order from the bottom in the Z-axis direction.

[0067] 6(B) is a cross-sectional view of a plane (YZ plane) including line BB parallel to the Z-axis direction in FIG. 5(D). This YZ plane is a plane passing through the cathode formation region. At approximately the center of the Y-axis direction in FIG. 6(B), a metal layer 115, a carbon layer 114, a solid electrolyte layer 113, a dielectric layer 112, an electrode foil 111, a dielectric layer 112, a solid electrolyte layer 113, and a carbon layer 114 are repeatedly stacked in this order from the bottom in the Z-axis direction.

[0068] In this way, the anode bodies can be easily fixed at a predetermined distance using only the insulator layer 116. Therefore, solid electrolyte layer 113, carbon layer 114, and metal layer 115 of a predetermined thickness can be more easily formed using a very simple structure. In other words, the difficulty of the process of forming solid electrolytic capacitor 1 can be prevented from increasing, and the desired capacitor capacitance can be obtained.

[0069] In addition, in this configuration, the insulator layer 116 is composed of two layers: a first insulator layer 1161 that can be used as a dam when forming the solid electrolyte layer 113, etc., and a second insulator layer 1162 whose main function is to connect multiple anode bodies. This further reduces the difficulty of the process of forming the solid electrolytic capacitor 1, making it easier to obtain the desired capacitor capacitance even when the product dimensions are specified.

[0070] Furthermore, by forming metal layer 115 on the outer periphery of each capacitor element 11, it is possible to achieve a reduction in ESR.

[0071] [Second embodiment] A solid electrolytic capacitor 1A according to a second embodiment of the present invention will be described with reference to the drawings. Figures 7(A), 7(B), 7(C), and 7(D) are cross-sectional views of a laminate according to the second embodiment. Figure 8(A) is a cross-sectional view taken along line AA passing through the insulator layer 116 in Figure 7(A), and Figure 8(B) is a cross-sectional view taken along line CC passing through the cathode formation region in Figure 7(D).

[0072] 7(A), 7(B), 7(C), 7(D), 8(A), and 8(B), the solid electrolytic capacitor 1A according to the second embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in that it has a solid electrolyte layer 113A, a carbon layer 114A, and a metal layer 115A. The other configuration of the solid electrolytic capacitor 1A according to the second embodiment is the same as that of the solid electrolytic capacitor 1 according to the first embodiment, and a description of the same parts will be omitted.

[0073] As in the first embodiment, as shown in Fig. 7(A), an insulator layer 116 (first insulator layer 1161 and second insulator layer 1162) is formed near one end of the anode body where the dielectric layer 112 is formed on the electrode foil 111. At this time, the anode bodies are stacked to form a laminate 10 so that the multiple insulator layers 116 abut against each other. In the second embodiment, the anode spacing is formed to be smaller than in the first embodiment.

[0074] The region of the laminate 10 where the insulator layer 116 is formed is hot-pressed. As a result, the multiple anode bodies in the laminate 10 are fixed so as to be approximately parallel to the Z-axis direction with the insulator layer 116 as the base point. The multiple anode bodies are preferably divided into an anode formation region and a cathode formation region by the insulator layer 116. In other words, the insulator layer 116 is preferably formed in the boundary region that separates the anode terminal region and the cathode terminal region.

[0075] Next, as shown in FIG. 7(B), a solid electrolyte layer 113A is formed in the cathode formation region of the laminate 10. At this time, the solid electrolyte layer 113A fills the spaces between the multiple anode bodies, in other words, the spaces formed by the anode gaps. As a result, the solid electrolyte layer 113A is integrally formed without any gaps in the Z-axis direction. The viscosity of the solid electrolyte layer 113A is preferably higher than that of the solid electrolyte layer 113 of the first embodiment. However, the viscosity of the solid electrolyte layer 113A is preferably low so that it can penetrate the enlarged surface of the porous layer 111L. Therefore, it is more preferable to use different viscosities depending on whether the solid electrolyte layer 113A penetrates the porous layer 111L or is formed between multiple anode bodies.

[0076] 7(C), the carbon layer 114A is formed to cover the outer periphery of the solid electrolyte layer 113A. At this time, the carbon layer 114A covers the end of the solid electrolyte layer 113A so as to expose the end.

[0077] 7(D), the metal layer 115A is formed so as to cover the outer periphery of the carbon layer 114A. At this time, the metal layer 115A covers the carbon layer 114A so as to expose the end portion thereof.

[0078] Fig. 8(A) is a cross-sectional view taken along a plane (YZ plane) including line AA parallel to the Z-axis direction in Fig. 7(A). This YZ plane is a plane passing through insulator layer 116. At approximately the center in the Y-axis direction in Fig. 8(A), a first insulator layer 1161, a dielectric layer 112, an electrode foil 111, a dielectric layer 112, a first insulator layer 1161, and a second insulator layer 1162 are repeatedly stacked in this order from the bottom in the Z-axis direction.

[0079] 8(B) is a cross-sectional view of a plane (YZ plane) including line CC parallel to the Z-axis direction in FIG. 7(D). This YZ plane is a plane passing through the cathode formation region. As shown in FIG. 8(B), the outer periphery of the cathode formation region (the outer periphery of solid electrolyte layer 113A) is covered with carbon layer 114A. Furthermore, the outer periphery of carbon layer 114A is covered with metal layer 115A.

[0080] 8(B), the structure is such that, starting from the bottom layer in the Z-axis direction, solid electrolyte layer 113A, dielectric layer 112, electrode foil 111, dielectric layer 112, and solid electrolyte layer 113A are repeatedly laminated, excluding metal layer 115A and carbon layer 114A. In this laminated state, carbon layer 114A and metal layer 115A are used to cover the outer periphery.

[0081] With this configuration, capacitor element 11 and laminate 20, in which electrode foil 111, dielectric layer 112, solid electrolyte layer 113A, carbon layer 114A, and metal layer 115A are laminated, can be easily formed.

[0082] In this way, the anode bodies can be easily fixed at a predetermined distance using only the insulator layer 116. Therefore, solid electrolyte layer 113A, carbon layer 114A, and metal layer 115A of a predetermined thickness can be more easily formed using a very simple structure. In other words, the difficulty of the process of forming solid electrolytic capacitor 1A can be prevented from increasing, and the desired capacitor capacitance can be obtained.

[0083] Furthermore, since only solid electrolyte layer 113A is formed between adjacent anode bodies, it is possible to further reduce the thickness of laminate 20. In other words, in a situation where the product dimensions are specified, the number of laminated capacitor elements 11 can be increased for the same height.

[0084] [Third embodiment] A solid electrolytic capacitor 1B according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 9 is a cross-sectional view of the solid electrolytic capacitor according to the third embodiment.

[0085] 9, the solid electrolytic capacitor 1B according to the third embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in that the width of the second insulator layer 1162B is defined. The other configuration of the solid electrolytic capacitor 1B according to the third embodiment is the same as that of the solid electrolytic capacitor 1 according to the first embodiment, and a description of similar parts will be omitted.

[0086] The configuration shown in FIG. 9 is a cross-sectional view of a plane (YZ plane) including line AA parallel to the Z-axis direction (see FIG. 5(A)). This YZ plane is a plane passing through the insulator layer 116B. In this case, the length (first width) of the first insulator layer 1161 in the Y-axis direction is greater than the length (second width) of the second insulator layer 1162B. More specifically, the second width is approximately 60% or more of the first width. More preferably, the second width is approximately 90% or more of the first width. Note that the Z-axis direction in FIG. 9 corresponds to the "first direction" in the present invention, and the Y-axis direction corresponds to the "second direction" in the present invention.

[0087] Even with this configuration, the anode body can be easily fixed at a predetermined distance using only insulator layer 116B. Therefore, solid electrolyte layer 113 and carbon layer 114 of a predetermined thickness can be more easily formed using a very simple structure. In other words, the difficulty of the process of forming solid electrolytic capacitor 1B can be prevented from increasing, and the desired capacitor capacitance can be obtained.

[0088] Furthermore, by making the length (second width) of the second insulator layer 1162B approximately 60% or more of the length (first width) of the first insulator layer 1161, leakage of the solid electrolyte layer 113, the carbon layer 114, and the metal layer 115 to the anode formation region side can be prevented, thereby making it possible to prevent short circuits.

[0089] The present specification discloses the following:

[0090] <1> a plurality of valve metal substrates each having a dielectric layer on at least one of their main surfaces and divided into an anode terminal region and a cathode formation region; an insulator layer provided to have a predetermined thickness in a boundary region between the anode terminal region and the cathode formation region; a solid electrolyte layer provided on the dielectric layer in the cathode formation region; a conductive layer provided on the solid electrolyte layer; Equipped with The plurality of laminated valve metal substrates are The cathode forming regions are bonded using the insulator layer, and are spaced apart according to the predetermined thickness of the insulator layer; the solid electrolyte layer is continuously formed in the cathode forming regions of the plurality of valve metal substrates and in a portion of the insulator layer; Solid electrolytic capacitor element.

[0091] <2> the thickness of the insulator layer in the stacking direction of the plurality of valve metal substrates is 20 μm or more and 140 μm or less; <1> The solid electrolytic capacitor element according to claim 1.

[0092] <3> The insulator layer is a first insulating layer disposed on the boundary region; a second insulator layer provided on the first insulator layer; having <1> or <2> The solid electrolytic capacitor element according to claim 1.

[0093] <4> The first insulating layer and the second insulating layer are made of the same material. <3> The solid electrolytic capacitor element according to claim 1.

[0094] <5> The first insulating layer and the second insulating layer are made of different materials. <3> The solid electrolytic capacitor element according to claim 1.

[0095] <6> In a plane including a first direction in which the plurality of valve metal substrates are stacked and a second direction perpendicular to the first direction, a second width of the second insulating layer parallel to the second direction is 60% or more of a first width of the first insulating layer parallel to the second direction; <3> ~ <5> 10. The solid electrolytic capacitor element according to claim 9, wherein

[0096] <7> the conductive layer includes a carbon layer and a metal layer, and the metal layer is provided on the carbon layer. <1> The solid electrolytic capacitor element according to claim 1.

[0097] <8> <1> a solid electrolytic capacitor element according to an insulating resin body that encapsulates the solid electrolytic capacitor element; external electrodes connected to the anode terminal region and the conductive layer of the solid electrolytic capacitor element, respectively; A solid electrolytic capacitor comprising:

[0098] <9> a first step of forming an insulator layer in a boundary region between an anode terminal region and a cathode formation region in a plurality of valve metal substrates each having a dielectric layer on at least one main surface thereof and divided into an anode terminal region and a cathode formation region; a second step of forming a first laminate by using the insulator layer, in which the cathode forming regions of the plurality of valve metal substrates are laminated so as to be spaced apart at predetermined intervals; a third step of forming a solid electrolyte layer on the dielectric layer in the cathode formation region; a fourth step of forming a conductor layer on the solid electrolyte layer; a fifth step of forming a second laminate on the first laminate, the second laminate including the solid electrolyte layer and the conductor layer formed on the plurality of valve metal substrates; a sixth step of sealing the second laminate with an insulating resin; a seventh step of forming external electrodes in the anode terminal region and the cathode formation region; The method for manufacturing a solid electrolytic capacitor includes the steps of:

[0099] <10> In the second step, The first laminate is laminated so that the predetermined interval is 20 μm or more and 140 μm or less. <9> 10. A method for producing the solid electrolytic capacitor according to claim 9. [Explanation of symbols]

[0100] F1…Front page F2…Second side F3…Side 3 F4…Fourth side F5…Side 5 F6…Side 6 1, 1A, 1B...Solid electrolytic capacitor 10, 20...Laminate 11...Capacitor element 40...Insulating resin body 111...Electrode foil 111F…electrode layer 111L...Porous layer 112...Dielectric layer 113,113A…Solid electrolyte layer 114, 114A...Carbon layer 115,115A…Metal layer 116, 116B...insulator layer 400...Sealing body 401...Top 402...Bottom 403...Side 1 404…Second side 50...Conductive adhesive 500...Mold 501...First external electrode 502…Second external electrode 1161...First insulating layer 1162...Second insulating layer

Claims

1. a plurality of valve metal substrates each having a dielectric layer on at least one of their main surfaces and divided into an anode terminal region and a cathode formation region; an insulator layer provided to have a predetermined thickness in a boundary region between the anode terminal region and the cathode formation region; a solid electrolyte layer provided on the dielectric layer in the cathode formation region; a conductive layer provided on the solid electrolyte layer; Equipped with The plurality of laminated valve metal substrates are The cathode forming regions are bonded using the insulator layer, and are spaced apart according to the predetermined thickness of the insulator layer; the solid electrolyte layer is continuously formed in the cathode forming regions of the plurality of valve metal substrates and in a portion of the insulator layer; Solid electrolytic capacitor element.

2. 2. The solid electrolytic capacitor element according to claim 1, wherein the thickness of the insulating layer in the stacking direction of the plurality of valve metal substrates is 20 [mu]m or more and 140 [mu]m or less.

3. The insulator layer is a first insulating layer disposed on the boundary region; a second insulator layer provided on the first insulator layer; The solid electrolytic capacitor element according to claim 1 or 2, comprising:

4. 4. The solid electrolytic capacitor element according to claim 3, wherein the first insulating layer and the second insulating layer are made of the same material.

5. 4. The solid electrolytic capacitor element according to claim 3, wherein the first insulating layer and the second insulating layer are made of different materials.

6. In a plane including a first direction in which the plurality of valve metal substrates are stacked and a second direction perpendicular to the first direction, 4. The solid electrolytic capacitor element according to claim 3, wherein the second width of the second insulator layer parallel to the second direction is 60% or more of the first width of the first insulator layer parallel to the second direction.

7. 2. The solid electrolytic capacitor element according to claim 1, wherein the conductive layer includes a carbon layer and a metal layer, and the metal layer is provided on the carbon layer.

8. The solid electrolytic capacitor element according to claim 1; an insulating resin body that encapsulates the solid electrolytic capacitor element; external electrodes connected to the anode terminal region and the conductive layer of the solid electrolytic capacitor element, respectively; A solid electrolytic capacitor comprising:

9. a first step of forming an insulator layer in a boundary region between an anode terminal region and a cathode formation region in a plurality of valve metal substrates each having a dielectric layer on at least one main surface thereof and divided into an anode terminal region and a cathode formation region; a second step of forming a first stack using the insulator layer, in which the cathode forming regions of the plurality of valve metal substrates are stacked so as to be spaced apart at predetermined intervals; a third step of forming a solid electrolyte layer on the dielectric layer in the cathode formation region; a fourth step of forming a conductor layer on the solid electrolyte layer; a fifth step of forming a second stack on the first stack, the second stack including the solid electrolyte layer and the conductor layer formed on the plurality of valve metal substrates; a sixth step of sealing the second laminate with an insulating resin; a seventh step of forming external electrodes in the anode terminal region and the cathode formation region; The method for manufacturing a solid electrolytic capacitor includes the steps of:

10. In the second step, The method for manufacturing a solid electrolytic capacitor according to claim 9 , wherein the first laminate is laminated so that the predetermined interval is 20 μm or more and 140 μm or less.

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