Solid electrolytic capacitor and method for manufacturing the solid electrolytic capacitor

Abstract

A solid electrolytic capacitor according to the present invention comprises: a sheet laminate formed by alternately laminating a plurality of flat film-shaped capacitor elements and a plurality of flat film-shaped cathode electrode foils with a conductive adhesive interposed therebetween; and an insulating resin that seals the sheet laminate. Each of the flat film-shaped capacitor elements comprises: a flat film-shaped anode electrode foil; a dielectric layer formed on the surface of the anode electrode foil; a first dam formed on the surface of the dielectric layer; and a solid electrolyte layer formed within a region regulated by the first dam. The conductive adhesive is formed within a region regulated by a second dam overlapping at least the first dam. The second dam is formed so as to cover a boundary section between the solid electrolyte layer and the first dam.

Description

[Technical Field]

[0001] The present invention relates to a solid electrolytic capacitor having a structure in which a laminate of a plurality of capacitor elements is molded with an insulating resin. [Background technology]

[0002] Patent Document 1 describes a method for manufacturing a solid electrolytic capacitor and a solid electrolytic capacitor. The solid electrolytic capacitor described in Patent Document 1 includes a plurality of flat-film capacitor elements and a plurality of metal foils (cathodes). The flat-film capacitor elements include a foil-like valve metal substrate, a porous portion of the valve metal substrate and a dielectric layer formed on the surface thereof, and a solid electrolyte layer formed on the surface of the dielectric layer.

[0003] More specifically, the device has the following configuration: In Patent Document 1, a mask layer is formed on the surface of the dielectric layer to cover the ends and sides of each element region. A solid electrolyte layer is formed in the region surrounded by this mask layer. Furthermore, an insulating adhesive layer is formed so as to overlap this mask layer, and a conductor layer is formed on this solid electrolyte layer.

[0004] The flat film capacitor elements thus formed and the metal foils are stacked alternately to form an element stack, which is then sealed with an insulating resin.

[0005] Patent Document 2 describes a surface-mount thin capacitor. The cathode part of the surface-mount thin capacitor described in Patent Document 2 is formed by laminating a conductive polymer, a graphite layer, and a silver paste layer on the surface of an anode (aluminum foil). A resist resin is formed at the boundary between this anode (aluminum foil) and the cathode part. An insulating resin is formed so as to cover a portion of this resist resin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-79866 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-129936 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in a solid electrolytic capacitor such as that shown in Patent Document 1, when a flat-film capacitor element and a valve metal substrate (metal foil) having a dielectric layer formed on its surface are laminated, the conductive layer spreads. If a gap exists at the boundary between the mask layer and the solid electrolyte layer, the dielectric layer may be exposed. Even if no gap exists between the mask layer and the solid electrolyte layer when they are formed, the mask layer and the solid electrolyte layer may shrink due to subsequent heating and pressure treatments during lamination. In other words, the boundary between the mask layer and the solid electrolyte layer may be exposed, potentially bringing the conductive layer into contact with the valve metal substrate. This can increase leakage current and cause a short circuit.

[0008] On the other hand, the surface-mount thin capacitor shown in Patent Document 2 has an insulating resin formed to cover a portion of the resist resin formed at the boundary between the anode and cathode portions, as described above. However, because the insulating resin only covers a portion of the resist resin, when re-chemical formation is performed, the resist resin and conductive polymer shrink, and the chemical formation solution penetrates between the resist resin and the conductive polymer. This creates a gap between the resist resin and the conductive polymer. Therefore, the configuration of Patent Document 2 may also have the same problems as Patent Document 1.

[0009] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a solid electrolytic capacitor that can suppress short circuits between the anode and cathode and achieve high reliability. [Means for solving the problem]

[0010] The solid electrolytic capacitor of the present invention comprises a sheet laminate formed by alternately stacking a plurality of flat-film capacitor elements and a plurality of flat-film cathode electrode foils with a conductive adhesive interposed therebetween, and an insulating resin sealing the sheet laminate. The flat-film capacitor element comprises a flat-film anode electrode foil, a dielectric layer formed on the surface of the anode electrode foil, a first dam formed on the surface of the dielectric layer, and a solid electrolyte layer formed within the region defined by the first dam. The conductive adhesive is formed within the region defined by at least a second dam overlapping the first dam. The second dam is formed so as to cover the boundary between the solid electrolyte layer and the first dam.

[0011] With this configuration, even when the capacitor element and the cathode foil are laminated together with the conductive adhesive, the conductive adhesive can be prevented from coming into contact with the solid electrolyte layer, thereby preventing a short circuit between the anode and the cathode. [Effects of the Invention]

[0012] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a solid electrolytic capacitor that can suppress short circuits between the anode and cathode and achieve high reliability. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a side cross-sectional view showing the configuration of the solid electrolytic capacitor according to the first embodiment. [Figure 2] Figure 2(A) is a side cross-sectional view showing the configuration of a set of a capacitor element and a cathode electrode before singulation, Figure 2(B) is a side cross-sectional view showing the configuration of a capacitor element before singulation, and Figure 2(C) is a side cross-sectional view showing the configuration of a set of a capacitor element and a cathode electrode after singulation. [Figure 3] FIG. 3(A) is a diagram schematically illustrating the structure of a capacitor element and a cathode electrode of the present invention, and FIG. 3(B) is a diagram schematically illustrating the structure of a capacitor element and a cathode electrode of a conventional configuration. [Figure 4]FIG. 4(A) is a plan view schematically showing the structure of a capacitor element and a cathode electrode of the present invention, and FIG. 4(B) is a plan view schematically showing the structure of a capacitor element and a cathode electrode of a conventional configuration. [Figure 5] FIG. 5 is a flowchart showing an example of a schematic flow of the method for manufacturing the solid electrolytic capacitor according to this embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of a process for forming a capacitor element sheet. [Figure 7] FIG. 7(A) is an external perspective view showing the shapes of the anode electrode and dielectric layer of the capacitor element before singulation, and FIG. 7(B) is an external perspective view showing the shape of the capacitor element before singulation. [Figure 8] FIG. 8 is an external view of the multi-state device. [Figure 9] FIG. 9 is an external perspective view showing the shape of the cathode electrode before being divided into individual pieces. [Figure 10] FIG. 10 is a flowchart showing an example of a process for forming a sheet stack. [Figure 11] 11(A) and 11(B) are external perspective views showing a state in which second dams are formed on the capacitor element sheet. [Figure 12] 12(A) and 12(B) are external perspective views showing a state in which a second dam and an adhesive are formed on the capacitor element sheet. [Figure 13] 13(A) and 13(B) are exploded perspective views showing the state in which the capacitor element sheet and the cathode electrode sheet are laminated together. [Figure 14] Figure 14(A) is an exploded perspective view showing the stacked state of capacitor element sheets and cathode electrode sheets in a multi-layered state, and Figure 14(B) is an external perspective view showing the stacked state of capacitor element sheets and cathode electrode sheets in a multi-layered state. [Figure 15] FIG. 15 is an exploded perspective view showing the state of the capacitor element sheets and the cathode electrode sheets in a multi-layer state. [Figure 16]FIG. 16(A) is a side cross-sectional view showing the configuration of a set of a capacitor element and a cathode electrode before singulation in the second embodiment, and FIG. 16(B) is a side cross-sectional view showing the configuration of the capacitor element before singulation. DETAILED DESCRIPTION OF THE INVENTION

[0014] [First embodiment] A solid electrolytic capacitor according to a first embodiment of the present invention and a method for manufacturing the solid electrolytic capacitor will be described with reference to the drawings.

[0015] (Explanation of the Schematic Configuration of Solid Electrolytic Capacitor 1) First, the structure of a solid electrolytic capacitor according to an embodiment of the present invention will be described. Fig. 1 is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to a first embodiment. In Fig. 1, only the insulating resin and external electrodes are hatched to make the drawing easier to see. Fig. 2(A) is a side cross-sectional view showing the configuration of a set of capacitor elements and cathode electrodes before singulation. Fig. 2(B) is a side cross-sectional view showing the configuration of a set of capacitor elements and cathode electrodes after singulation. Fig. 2(C) is a side cross-sectional view showing the configuration of a set of capacitor elements and cathode electrodes after singulation.

[0016] As shown in FIGS. 1, 2(A), 2(B), and 2(C), the solid electrolytic capacitor 1 includes a capacitor element laminate 100, an insulating resin 50, an external electrode 61, and an external electrode 62. The capacitor element laminate 100 includes a plurality of flat-film capacitor elements 10, a plurality of flat-film cathode electrodes 20, a second dam 30, and an adhesive 40. While FIG. 1 shows four flat-film capacitor elements 10 and four cathode electrodes, the number of such elements is not limited to four. The cathode electrode 20 corresponds to the "cathode electrode foil" of the present invention. The side cross-sectional views in FIGS. 1, 2(A), 2(B), and 2(C) are cross-sectional views taken along a plane perpendicular to the top surface 101 and bottom surface 102 of the capacitor element laminate 100 in FIG. 1.

[0017] As shown in FIG. 2(B), the capacitor element 10 includes a flat film-like anode electrode 11, a dielectric layer 12, and a CP layer (solid electrolyte layer) 13.

[0018] Although detailed structural illustration is omitted in FIG. 2, the anode 11 has numerous pores. In other words, the anode 11 is porous (a porous body). The thickness ratio of the porous portion on one side of the anode 11 to the core metal portion and the porous portion on the other side is approximately 1:1:1. A dielectric layer 12 covers the outer surface of the anode 11. Because detailed structural illustration of the anode 11 is omitted in FIG. 2, the dielectric layer 12 is illustrated as if it were covering the macroscopic surface of the anode 11. In reality, the dielectric layer 12 covers not only the macroscopic surface of the anode 11 but also the surfaces of the numerous pores in the anode 11. The anode 11 corresponds to the "anode electrode foil" of the present invention.

[0019] The CP layer 13 covers the surface of the dielectric layer 12. The CP layer 13 is formed inside a frame-shaped first dam 14. The first dam 14 is insulating. The first dam 14 limits the area in which the CP layer 13 is formed. In the first embodiment, as described in the manufacturing method described below, the first dam 14 is formed in a frame shape, and then the CP layer 13 is formed inside the first dam 14. However, depending on the manufacturing method of the capacitor element 10, for example, when the capacitor element 10 is manufactured in an individualized state from the beginning, the first dam 14 does not have to be formed in a frame shape. That is, the first dam 14 may be formed on one side, or on two sides having a corner. Furthermore, the first dam 14 may be formed on two opposing sides in a planar view.

[0020] The CP layer 13 has a laminated structure of an inner layer CP (inner layer solid electrolyte layer) 131 and an outer layer CP (outer layer solid electrolyte layer) 132. The inner layer CP131 is formed on the surface of the dielectric layer 12, and the outer layer CP132 is formed on the surface of the inner layer CP131.

[0021] The plurality of capacitor elements 10 and the plurality of cathode electrodes 20 are alternately stacked so that their flat film surfaces are parallel to each other and overlap each other in plan view.

[0022] A second dam 30 and an adhesive 40 are disposed between adjacent capacitor elements 10 and cathode electrodes 20. The second dam 30 is insulating. The adhesive 40 is conductive. The adhesive 40 corresponds to the "conductive adhesive" of the present invention.

[0023] Second dam 30 is frame-shaped. Adhesive 40 is disposed inside the frame defined by second dam 30. Adhesive 40 bonds adjacent capacitor elements 10 and cathode electrodes 20 together.

[0024] As shown in Figure 2(B), the second dam 30 is formed so as to overlap the outer layer CP132. In other words, it is formed so as to cover the end of the first dam 14 and the end of the outer layer CP132. A more detailed structure will be described later. The second dam 30 is made of an insulating material such as insulating resin.

[0025] The second dam 30 has a dam adjustment portion 30L. This dam adjustment portion 30L is used to control the volume of the second dam 30 when it is applied. In other words, by using the dam adjustment portion 30L, unnecessary expansion of the second dam 30 during lamination is suppressed. When the second dam 30 is unnecessarily expanded, the second dam 30 enters, for example, the anode through-holes 19C, 19L or the cathode through-holes 29C, 29L (the detailed configuration will be described below). However, by having the dam adjustment portion 30L, it is possible to suppress the molding of the insulating resin 50 being hindered and the occurrence of molding defects.

[0026] The dam adjustment portion 30L is formed by a printing pattern. The dam adjustment portion 30L may be a through-hole or may have a shape such as a recess having a bottom surface in the second dam 30. The size (width, length) of the dam adjustment portion 30L may be determined according to the volume of the second dam 30.

[0027] Second dam 30 is expanded by applying heat and pressure to capacitor element 10 and cathode electrode 20. This reduces the difference in thickness between dam adjusting portion 30L and the other portions.

[0028] In this stacked state, the first ends 10E1 (see FIG. 2(C)) of the plurality of capacitor elements 10 are located at approximately the same position in side view. Similarly, the second ends 10E2 (see FIG. 2(C)) of the plurality of capacitor elements 10 are located at approximately the same position in side view. Furthermore, the first ends 20E1 (see FIG. 2(C)) of the plurality of cathode electrodes 20 are located at approximately the same position in side view. Similarly, the second ends 20E2 (see FIG. 2(C)) of the plurality of cathode electrodes 20 are located at approximately the same position in side view.

[0029] The first ends 10E1 of the plurality of capacitor elements 10 and the second ends 20E2 of the plurality of cathode electrodes 20 are arranged on the first end side of the capacitor element stack 100. The first ends 10E1 of the plurality of capacitor elements 10 protrude outward beyond the second ends 20E2 of the plurality of cathode electrodes 20.

[0030] The second ends 10E2 of the plurality of capacitor elements 10 and the first ends 20E1 of the plurality of cathode electrodes 20 are arranged on the second end side of the capacitor element stack 100. The first ends 20E1 of the plurality of cathode electrodes 20 protrude outward beyond the second ends 10E2 of the plurality of capacitor elements 10.

[0031] With such a structure, the capacitor element laminate 100 is realized.

[0032] The capacitor element stack 100 is sealed with insulating resin 50. More specifically, the insulating resin 50 covers the capacitor element stack 100 except for first ends 10E1 of the plurality of capacitor elements 10 (first ends 10E1 of the anode electrodes 11) and first ends 20E1 of the plurality of cathode electrodes 20.

[0033] The external electrode 61 covers the first end (first end 10E1 of the anode electrode 11) of the insulating resin 50. The external electrode 61 is connected to the first ends 10E1 of the anode electrodes 11 of the plurality of capacitor elements .

[0034] The external electrode 62 covers the second end (the first end 20E1 of the cathode electrode 20) of the insulating resin 50. The external electrode 62 is connected to the first ends 20E1 of the plurality of cathode electrodes 20.

[0035] The solid electrolytic capacitor 1 is realized by the above configuration.

[0036] (Detailed structure of solid electrolytic capacitor 1) Next, the detailed structures of the capacitor element 10 and the cathode electrode 20 constituting the solid electrolytic capacitor 1 will be described using FIGS. 3A and 3B. FIG. 3A is a side cross-sectional view schematically illustrating the structure of the capacitor element 10 and the cathode electrode 20, and is an enlarged view of the structure of FIG. 2A described above. FIG. 3B is a side cross-sectional view schematically illustrating the structure of the capacitor element 10 and the cathode electrode 20 according to a conventional configuration. In FIGS. 3A and 3B, the structure of one main surface of the capacitor element 10 on which the cathode electrode 20 is disposed will be described, but the other main surface opposite the one main surface has a similar structure. The side cross-sectional views in FIGS. 3A and 3B are cross-sectional views taken along a plane perpendicular to the top surface 101 and bottom surface 102 of the capacitor element laminate 100 in FIG. 1.

[0037] Note that the respective structures are enlarged and exaggerated for ease of understanding. Also, although only one set of capacitor element 10 and cathode electrode 20 is shown in Figures 3(A) and 3(B), solid electrolytic capacitor 1 is formed by stacking multiple such sets.

[0038] 3(A), an outer layer CP132 is formed within an area surrounded by the first dam 14. A boundary BD exists at the boundary between the inside of the area formed by this first dam 14 and the area where the outer layer CP132 is formed. The existence of this boundary BD exposes the dielectric layer 12. For convenience, the boundary BD and the area where the dielectric layer 12 is exposed indicate the same portion.

[0039] However, in the present invention, the second dam 30 is formed to cover this boundary portion BD. That is, even if the dielectric layer 12 is exposed, the second dam 30 fills the exposed portion. Therefore, the dielectric layer 12 is not exposed.

[0040] By stacking capacitor element 10 having this configuration and multiple cathode electrodes 20 via adhesive 40, it is possible to prevent contact between adhesive 40 and anode electrode 11. In other words, short circuits between the anode and cathode are prevented.

[0041] Next, the configuration will be described in more detail using Figures 3(A), 4(A), and 4(B). Figure 4(A) is a plan view showing an overview of capacitor element 10 with adhesive 40 applied thereto. Figure 4(B) is a plan view showing an overview of capacitor element 10 with adhesive 40 applied thereto in a conventional configuration. Note that in Figures 4(A) and 4(B), the hatching is different from that in other figures to make the dielectric layer 12 easier to understand, and each structure is enlarged and exaggerated to make the explanation easier to understand.

[0042] 3(A) and 4(A), the positional relationship between the inner peripheral portion 14P of the first dam 14 and the inner peripheral portion 30P of the second dam 30 is compared. In the present invention, the inner peripheral portion 30P is formed inside the capacitor element 10 (inside in plan view) at a distance d from the inner peripheral portion 14P around the entire periphery. In other words, the second dam 30 is formed so as to extend further inside the capacitor element 10 than the first dam 14 at the distance d. The distance d may be in the range of approximately 50 μm to approximately 100 μm.

[0043] With this configuration, the boundary BD is covered by the second dam 30. That is, even if the adhesive 40 spreads due to a process such as heating and pressurizing, the adhesive 40 does not come into contact with the dielectric layer 12 (boundary BD). That is, a short circuit between the anode electrode 11 and the cathode electrode 20 can be suppressed.

[0044] (Method of manufacturing solid electrolytic capacitor 1) 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 schematic flow of the method for manufacturing the solid electrolytic capacitor according to this embodiment.

[0045] A capacitor element sheet is formed (FIG. 5: S11). A plurality of capacitor elements 10, each forming a different solid electrolytic capacitor 1, are formed in an array on the capacitor element sheet.

[0046] Next, the capacitor element sheet and the cathode electrode sheet are laminated with adhesive 40 sandwiched between them to form a sheet laminate (FIG. 5: S12). Note that the cathode electrode sheet has a plurality of cathode electrodes 20 formed in an array, which form different solid electrolytic capacitors 1. This forms a structure in which a plurality of capacitor element laminates 100 are arranged in a plane. In other words, the sheet laminate is a structure in which a plurality of capacitor element laminates 100 are arranged in a plane.

[0047] Next, the sheet stack is sealed with insulating resin 50 (FIG. 5: S13). As will be described in detail later, at this time, through holes that penetrate from the top surface to the bottom surface of the sheet stack are provided in the sheet stack, and resin sealing is performed by compression molding.

[0048] The process up to this sealing with insulating resin 50 is carried out in a multi-state (state in which a plurality of what will become solid electrolytic capacitors 1 are arranged) before the solid electrolytic capacitor 1 is divided into individual pieces.

[0049] Next, the sheet laminate sealed with insulating resin 50 is cut into individual pieces (FIG. 5: S14). Specifically, cutting is performed along cutting lines E11, E12, S11, and S12 shown in FIG. 13(B), which will be described later. This results in multiple solid electrolytic capacitors 1 (referred to as "solid electrolytic capacitor 1 bodies") without external electrodes formed thereon. Thereafter, the solid electrolytic capacitor 1 bodies are secondary sealed with insulating resin 50. More specifically, the side surfaces of the solid electrolytic capacitor 1 bodies (surfaces cut along cutting lines S11 and S12 (top surface, bottom surface, and side surfaces other than the end surfaces where the anode electrode 11 and cathode electrode 20 are exposed)) are covered with the secondary sealing of insulating resin 50. This allows the anode electrode 11 and cathode electrode 20, which are unnecessarily exposed during singulation, to be covered with insulating resin 50.

[0050] Next, external electrodes 61 and 62 are formed on the end faces of the element body of solid electrolytic capacitor 1 (FIG. 5: S15).

[0051] Next, each step will be described in more detail.

[0052] (Capacitor element sheet forming process) Fig. 6 is a flowchart showing an example of a process for forming a capacitor element sheet. Fig. 7(A) is an external perspective view showing the shapes of the anode electrode and dielectric layer of the capacitor element before singulation, and Fig. 7(B) is an external perspective view showing the shape of the capacitor element before singulation. Fig. 8 is an external view in a multi-layer state.

[0053] Anode 11 is subjected to chemical conversion treatment to form dielectric layer 12 (FIG. 6: S111). At this time, a large number of holes are formed on the surface of anode 11 by etching, and the area near the surface of anode 11 is porous. Dielectric layer 12 covers the surface of anode 11, including the inner surfaces of the holes.

[0054] Next, anode through holes are formed in the anode 11 (FIG. 6: S112). More specifically, as shown in FIG. 7(A), a plurality of cylindrical anode through holes 19C and groove-shaped anode through holes 19L are formed in the anode 11. The cylindrical anode through holes 19C and the groove-shaped anode through holes 19L are alternately arranged along the direction in which the portions that will become the anodes 11 are arranged. The cylindrical anode through holes 19C are formed at positions that will form first ends 10E1 of the anodes 11, and the groove-shaped anode through holes 19L are formed at positions that straddle the portions that will become adjacent anodes 11 and at positions that will form second ends 10E2 of the adjacent anodes 11.

[0055] Next, a CP layer (solid electrolyte layer) 13 is formed on the surface of the dielectric layer 12 (FIG. 6: S113). More specifically, as shown in FIG. 7(B), a first dam 14 having a frame-shaped opening is formed. Then, the CP layer 13 (a laminated structure of an inner layer CP131 and an outer layer CP132) is formed within the opening of the first dam 14.

[0056] As shown in FIG. 8, this structure is implemented in a multi-state in which a plurality of capacitor elements 10 (a structure consisting of an anode electrode 11, a dielectric layer 12, a CP layer 13, and a first dam 14) are arranged two-dimensionally.

[0057] (Cathode electrode sheet forming process) FIG. 9 is an external perspective view showing the shape of the cathode electrode before being divided into individual pieces.

[0058] 9 , a plurality of cylindrical cathode through holes 29C and groove-shaped cathode through holes 29L are formed in the cathode electrode 20. The cylindrical cathode through holes 29C and the groove-shaped cathode through holes 29L are alternately arranged along the direction in which the portions that will become the cathode electrodes 20 are arranged. The cylindrical cathode through holes 29C are formed at positions that will form first ends 20E1 of the cathode electrodes 20, and the groove-shaped cathode through holes 29L are formed at positions that straddle the portions that will become adjacent cathode electrodes 20 and at positions that will form second ends 20E2 of the adjacent cathode electrodes 20.

[0059] (Sheet stack formation process) FIG. 10 is a flowchart showing an example of a process for forming a sheet laminate. FIG. 11 is an external perspective view showing a state in which second dams have been formed on capacitor element sheets, with FIG. 11(A) showing the multi-layer structure and FIG. 11(B) showing the portion of a single capacitor element. FIG. 12 is an external perspective view showing a state in which second dams and adhesive have been formed on capacitor element sheets, with FIG. 12(A) showing the multi-layer structure and FIG. 12(B) showing the portion of a single capacitor element. FIGS. 13(A) and 13(B) are exploded perspective views showing a state in which capacitor element sheets and cathode electrode sheets are laminated. FIGS. 13(A) and 13(B) show the portion corresponding to one solid electrolytic capacitor. FIG. 14(A) is an exploded perspective view showing a state in which capacitor element sheets and cathode electrode sheets are laminated in a multi-layer structure, and FIG. 14(B) is an external perspective view showing a state in which capacitor element sheets and cathode electrode sheets are laminated in a multi-layer structure. FIG. 15 is a diagram showing the configuration after the capacitor element sheets and cathode electrode sheets have been laminated and heated and pressed.

[0060] A second dam 30 is formed on the sheet laminate (FIG. 10: S121). More specifically, as shown in FIGS. 11(A) and 11(B), a second dam 30 having a frame-shaped opening is formed. The second dam 30 is formed at a position overlapping the first dam 14. Furthermore, the second dam 30 is formed to an area inside the inner frame of the first dam 14. However, the shape of the second dam 30 during printing is not limited to this, as long as the shape of the second dam 30 extends inside the inner frame of the first dam 14 during heating and pressurization, which will be described later.

[0061] In this case, the second dam 30 is formed by a printing pattern so as to have a dam adjusting portion 30L. Note that FIG. 11(A) shows an example in which the dam adjusting portion 30L is formed over the entire first dam 14. However, a configuration in which the dam adjusting portion 30L is not formed over the entire first dam 14 is also possible. In other words, the number of dam adjusting portions 30L may be formed according to the volume of the adhesive 40, similar to the size of the dam adjusting portion 30L described above.

[0062] Next, as shown in FIGS. 12(A) and 12(B), adhesive 40 is placed inside the opening of the second dam 30 (FIG. 10: S122).

[0063] Next, as shown in Figures 13(A), 13(B), 14(A), and 14(B), capacitor element sheets and cathode electrode sheets are alternately stacked (Figure 10: S123). More specifically, the capacitor element sheets and cathode electrode sheets are stacked so as to satisfy the following conditions:

[0064] When viewed in the stacking direction, the plurality of cylindrical anode through holes 19C in the capacitor element sheet and the groove-shaped cathode through holes 29L in the cathode electrode sheet overlap each other. When viewed in the stacking direction, the groove-shaped anode through-holes 19L in the capacitor element sheet and the plurality of cylindrical cathode through-holes 29C in the cathode electrode sheet overlap with each other. When viewed in the stacking direction, the groove-shaped anode through-hole 19L in the capacitor element sheet and the groove-shaped cathode through-hole 29L in the cathode electrode sheet overlap each other. The number of these through holes formed corresponds to the number of capacitor elements arranged in the sheet laminate, and therefore the sheet laminate is provided with a plurality of through holes that penetrate from the top surface to the bottom surface of the sheet laminate.

[0065] Next, the sheet laminate is heated and pressurized (FIG. 10: S124). This bonds the capacitor element sheets and the cathode electrode sheets with adhesive 40, forming a sheet laminate. As shown in FIG. 15, this heating and pressurization causes adhesive 40 to spread in a planar manner. However, because second dam 30 covers boundary portion BD, contact between adhesive 40 and anode electrode 11 can be suppressed. In other words, short-circuiting between the anode and cathode is suppressed.

[0066] Furthermore, this heating and pressurizing closes the dam adjusting portion 30L formed in the second dam 30. This allows the thickness of the second dam 30 to be adjusted, preventing the thickness of the second dam 30 from becoming unnecessarily thick. This allows the sheet laminate to have a low profile.

[0067] [Second embodiment] Next, a solid electrolytic capacitor according to a second embodiment will be described with reference to the drawings. Fig. 16(A) is a side cross-sectional view showing the configuration of a set of a capacitor element and a cathode electrode before singulation in the second embodiment, and Fig. 16(B) is a side cross-sectional view showing the configuration of the capacitor element before singulation.

[0068] 16(A) and 16(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 the cathode electrode 20A has a third dam 210. The other configuration of the solid electrolytic capacitor 1A is the same as that of the solid electrolytic capacitor 1, and a description of the same parts will be omitted.

[0069] 16(B), the cathode electrode 20A includes a third dam 210. Similar to the second dam 30, the third dam 210 is made of an insulating material such as an insulating resin.

[0070] The cathode electrode 20A and the capacitor element 10 are bonded together by applying heat and pressure via the adhesive 40. Even with this configuration, it is possible to prevent contact between the adhesive 40 and the anode electrode 11. The presence of the third dam 210 further prevents the adhesive 40 from spreading outward from the cathode electrode 20A.

[0071] (Explanation of an example of specific materials of each component of the solid electrolytic capacitor 1) (Capacitor element 10) The capacitor element 10 is realized, for example, using the following materials and thicknesses.

[0072] The anode electrode 11 is made of a metal such as aluminum, tantalum, niobium, titanium, zirconium, or magnesium, or an alloy containing these metals. The anode electrode 11 is preferably made of aluminum or an aluminum alloy. The anode electrode 11 may be made of any valve metal that exhibits a so-called valve action.

[0073] The anode electrode 11 is preferably flat, and the thickness of the core portion (the center portion not reached by the pores of the porous body) of the anode electrode 11 is preferably 5 μm or more and 100 μm or less. The thickness (thickness of one side) of the porous portion (the portion where the pores of the porous body are formed) is preferably 5 μm or more and 200 μm or less.

[0074] The dielectric layer 12 is preferably made of an oxide film of the anode electrode 11. For example, when an aluminum foil is used for the anode electrode 11, the dielectric layer 12 is formed by oxidizing the aluminum foil in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or their sodium salts or ammonium salts. The thickness of the dielectric layer 12 is preferably 1 nm or more and 100 nm or less.

[0075] The inner layer CP131 may be a PEDOT:PSS layer realized by, for example, 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 CP131 may be formed, for example, by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of the dielectric layer 12 using a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or by 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.

[0076] The thickness of the outer layer CP132 is preferably 2 μm or more and 20 μm or less The material of the outer layer CP132 is the same as the material of the inner layer CP131.

[0077] The adhesive 40 may be a mixture of an insulating resin such as an epoxy resin or a phenolic resin and conductive particles such as carbon or silver. Alternatively, the adhesive 40 may be a dispersion of a conductive polymer, or a dispersion of a conductive polymer to which a binder has been added.

[0078] The cathode electrode 20 is made of, for example, aluminum, titanium, copper, silver, etc. The thickness of the cathode electrode 20 is, for example, thinner than or approximately the same as the thickness of the anode electrode 11. The thickness of the cathode electrode 20 is preferably as thin as possible, about 5 μm to 50 μm, and preferably about 30 μm.

[0079] The insulating resin 50 may contain a filler. Examples of suitable resins include epoxy resin, phenol resin, polyimide resin, silicone resin, polyamide resin, and liquid crystal polymer. Examples of suitable fillers include insulating oxide particles such as silica particles, alumina particles, titania particles, and zirconia particles. The maximum diameter of the filler is preferably 30 μm or more and 40 μm or less. For example, a material containing silica particles in a solid epoxy resin and phenol resin is more preferable. [Explanation of symbols]

[0080] BD…Boundary part d...distance 1, 1A...Solid electrolytic capacitor 10...Capacitor element 10E1, 20E1...1st end 10E2, 20E2…2nd end 11...Anode electrode 12...Dielectric layer 14... First Dam 14P…Inner circumference 19C, 19L...Through hole for anode 20, 20A…Cathode electrode 29C, 29L...Through hole for cathode 30...Second Dam 30L…Dam adjustment section 30P…Inner circumference 40...Adhesive 50...Insulating resin 61, 62...External electrode 100... Capacitor element laminate 131...Inner CP 132...Outer layer CP 210...Third Dam

Claims

1. a sheet laminate formed by alternately laminating a plurality of flat film capacitor elements and a plurality of flat film cathode electrode foils via a conductive adhesive; an insulating resin that seals the sheet laminate; Equipped with The flat film capacitor element is a flat film-shaped anode electrode foil; a dielectric layer formed on the surface of the anode foil; a first dam having insulating properties formed on a surface of the dielectric layer; a solid electrolyte layer formed within a region defined by the first dam; Equipped with the conductive adhesive is formed at least within a region defined by a second dam having insulating properties and overlapping the first dam; a boundary portion between the solid electrolyte layer and the first dam at which the dielectric layer is exposed; The second dam is filled in the boundary portion.

2. The solid electrolytic capacitor according to claim 1 , wherein the second dam has a dam adjusting portion where no dam material is formed.

3. The size of the dam adjustment portion is determined according to the volume of the second dam. The solid electrolytic capacitor according to claim 2 .

4. forming a plurality of flat film capacitor elements; forming a plurality of flat film-shaped cathode electrode foils; a step of alternately stacking the plurality of flat film capacitor elements and the plurality of flat film cathode electrode foils via a conductive adhesive to form a sheet laminate; a step of sealing the sheet laminate with an insulating resin; and The step of forming the flat film capacitor element includes: forming a dielectric layer on the surface of the flat film-shaped anode electrode foil; forming a first dam having insulating properties on a surface of the dielectric layer; forming a solid electrolyte layer within a region defined by the first dam; and The step of forming the sheet laminate includes: forming an insulating second dam overlapping at least the first dam; forming the conductive adhesive within the area defined by the second dam; and In the step of forming the solid electrolyte layer, the solid electrolyte layer is formed to have a boundary portion between the first dam and the solid electrolyte layer, at least a portion of which exposes the dielectric layer; In the step of forming the second dam, The second dam is filled in the boundary portion. A method for manufacturing a solid electrolytic capacitor.

5. In the step of forming the sheet laminate, The method for manufacturing a solid electrolytic capacitor according to claim 4 , wherein the second dam has a dam adjusting portion where no dam material is formed.

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