JP7761133B2 - Solid electrolytic capacitor and method for manufacturing the solid electrolytic capacitor - Google Patents

Description

The present invention relates to a solid electrolytic capacitor having a structure in which a laminate of multiple capacitor elements is molded with insulating resin.

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 comprises multiple flat-film capacitor elements and multiple metal foils (cathodes). The flat-film capacitor elements comprise a foil-shaped valve metal substrate, a porous portion of the valve metal substrate, a dielectric layer formed on the surface, and a solid electrolyte layer formed on the surface of the dielectric layer.

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

The flat film capacitor elements and metal foils formed in this way are stacked alternately to form an element stack. The element stack is then sealed with insulating resin.

Patent Document 2 describes a surface-mount thin capacitor. The cathode portion 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 portion. An insulating resin is formed to cover part of this resist resin.

Japanese Patent Application Laid-Open No. 2019-79866 JP 2009-129936 A

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 wets and 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, such as during lamination. This means that 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 increases leakage current and may result in a short circuit.

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 seeps into the gap between the resist resin and the conductive polymer. This creates a gap between the resist resin and the conductive polymer. For this reason, the configuration of Patent Document 2 may also have the same problems as Patent Document 1.

Therefore, the 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.

The solid electrolytic capacitor of this invention comprises a sheet laminate formed by alternately stacking multiple flat-film capacitor elements and multiple flat-film cathode electrode foils via a conductive adhesive, and an insulating resin that seals 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 area defined by the first dam. The conductive adhesive is formed within the area defined by at least a second dam that overlaps the first dam. The second dam is formed to cover the boundary between the solid electrolyte layer and the first dam.

This configuration prevents the conductive adhesive from coming into contact with the solid electrolyte layer, even when the capacitor element and cathode electrode foil are laminated together with the conductive adhesive. This means that short circuits between the anode and cathode are prevented.

Therefore, the 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.

FIG. 1 is a side cross-sectional view showing the configuration of the solid electrolytic capacitor according to the first embodiment. 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. FIG. 3A is a diagram schematically illustrating the structure of a capacitor element and a cathode electrode according to the present invention, and FIG. 3B is a diagram schematically illustrating the structure of a capacitor element and a cathode electrode having a conventional configuration. FIG. 4A is a plan view schematically showing the structure of a capacitor element and a cathode electrode of the present invention, and FIG. 4B is a plan view schematically showing the structure of a capacitor element and a cathode electrode of a conventional configuration. 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. FIG. 6 is a flowchart showing an example of a process for forming a capacitor element sheet. FIG. 7A is an external perspective view showing the shapes of the anode electrode and dielectric layer of the capacitor element before singulation, and FIG. 7B is an external perspective view showing the shape of the capacitor element before singulation. FIG. 8 is an external view of the multi-state device. FIG. 9 is a perspective view showing the appearance of the cathode electrode before being divided into individual pieces. FIG. 10 is a flowchart showing an example of a process for forming a sheet stack. 11A and 11B are external perspective views showing a state in which second dams are formed on the capacitor element sheet. 12A and 12B are external perspective views showing a state in which a second dam and an adhesive are formed on the capacitor element sheet. 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(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. 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. 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.

[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.

(Explanation of the general configuration of the 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. Note that 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.

As shown in Figures 1, 2(A), 2(B), and 2(C), the solid electrolytic capacitor 1 comprises a capacitor element laminate 100, insulating resin 50, external electrode 61, and external electrode 62. The capacitor element laminate 100 comprises 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 Figure 1 shows four flat-film capacitor elements 10 and four cathode electrodes, this is not limitative. The cathode electrode 20 corresponds to the "cathode electrode foil" of the present invention. The side cross-sectional views in Figures 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 Figure 1.

As shown in Figure 2 (B), the capacitor element 10 comprises a flat film-shaped anode electrode 11, a dielectric layer 12, and a CP layer (solid electrolyte layer) 13.

Although detailed structure is not shown in Figure 2, the anode electrode 11 has a large number of holes. In other words, the anode electrode 11 is porous (a porous body). The thickness ratio of the porous portion on one side of the anode electrode 11 to the core metal portion and the porous portion on the other side is approximately 1:1:1. The dielectric layer 12 covers the outer surface of the anode electrode 11. Because detailed structure of the anode electrode 11 is not shown in Figure 2, the dielectric layer 12 is schematically shown as covering the macroscopic surface of the anode electrode 11. In reality, the dielectric layer 12 covers not only the macroscopic surface of the anode electrode 11, but also the surfaces of the numerous holes in the anode electrode 11. The anode electrode 11 corresponds to the "anode electrode foil" in this invention.

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 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 created 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.

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 CP 131 is formed on the surface of the dielectric layer 12, and the outer layer CP 132 is formed on the surface of the inner layer CP 131.

The multiple capacitor elements 10 and the multiple cathode electrodes 20 are stacked alternately so that their flat film surfaces are parallel and overlap when viewed in a plane.

A second dam 30 and 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 this invention.

The second dam 30 is frame-shaped. The adhesive 40 is disposed inside the frame defined by the second dam 30. This adhesive 40 bonds adjacent capacitor elements 10 and cathode electrodes 20 together.

As shown in FIG. 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.

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, using the dam adjustment portion 30L prevents the second dam 30 from unnecessarily expanding during stacking. 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 (detailed configuration is shown below). However, the presence of the dam adjustment portion 30L can prevent the molding of the insulating resin 50 from being hindered, thereby preventing molding defects from occurring.

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 with a bottom surface in the second dam 30, such as a recess. In addition, it is preferable to form the size (width, length) of the dam adjustment portion 30L according to the volume of the second dam 30.

In addition, by heating and pressurizing the capacitor element 10 and the cathode electrode 20, the second dam 30 is expanded. This reduces the difference in thickness between the dam adjustment portion 30L and other parts.

In this stacked state, the first ends 10E1 (see FIG. 2(C)) of the multiple capacitor elements 10 are located at approximately the same position when viewed from the side. Similarly, the second ends 10E2 (see FIG. 2(C)) of the multiple capacitor elements 10 are located at approximately the same position when viewed from the side. Furthermore, the first ends 20E1 (see FIG. 2(C)) of the multiple cathode electrodes 20 are located at approximately the same position when viewed from the side. Similarly, the second ends 20E2 (see FIG. 2(C)) of the multiple cathode electrodes 20 are located at approximately the same position when viewed from the side.

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

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

This structure results in the capacitor element stack 100.

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 the first ends 10E1 of the plurality of capacitor elements 10 (first ends 10E1 of the anode electrodes 11) and the first ends 20E1 of the plurality of cathode electrodes 20.

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

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

The above configuration realizes the solid electrolytic capacitor 1.

(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 the bottom surface 102 of the capacitor element laminate 100 in FIG. 1.

Note that each structure has been enlarged and exaggerated to make the explanation easier to understand. Also, while Figures 3(A) and 3(B) show only one set of capacitor element 10 and cathode electrode 20, the solid electrolytic capacitor 1 is formed by stacking multiple such sets.

As shown in Figure 3(A), an outer layer CP132 is formed within the area surrounded by the first dam 14. A boundary portion 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 presence of this boundary portion BD exposes the dielectric layer 12. For convenience, the boundary portion BD and the area where the dielectric layer 12 is exposed are shown as the same part.

However, in the present invention, the second dam 30 is formed to cover this boundary portion BD. In other words, even if the dielectric layer 12 is exposed, the second dam 30 penetrates into this exposed portion. Therefore, the dielectric layer 12 is not exposed.

By stacking the capacitor element 10 and multiple cathode electrodes 20 with adhesive 40 interposed therebetween, contact between the adhesive 40 and the anode electrode 11 can be prevented. In other words, short circuits between the anode and cathode are prevented.

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 the capacitor element 10 with adhesive 40 placed thereon. Figure 4(B) is a plan view showing an overview of the capacitor element 10 with adhesive 40 placed thereon 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.

As shown in Figures 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 at a distance d inside the capacitor element 10 (inside in plan view) around the entire circumference of the inner peripheral portion 14P. 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 a distance d. It is preferable that the distance d be in the range of approximately 50 μm to approximately 100 μm.

By configuring it in this manner, the boundary portion BD is covered by the second dam 30. In other words, even if the adhesive 40 becomes wet and spreads due to processing such as heating and pressurization, the adhesive 40 does not come into contact with the dielectric layer 12 (boundary portion BD). In other words, a short circuit between the anode electrode 11 and the cathode electrode 20 can be suppressed.

(Method for 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.

A capacitor element sheet is formed (Figure 5: S11). The capacitor element sheet is formed with an array of multiple capacitor elements 10, each of which forms a different solid electrolytic capacitor 1.

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

Next, the sheet stack is sealed with insulating resin 50 (Figure 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 using a compression mold.

The sealing with insulating resin 50 is performed in a multi-state (a state in which multiple solid electrolytic capacitors 1 are arranged) before the solid electrolytic capacitor 1 is separated into individual pieces.

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. The solid electrolytic capacitor 1 bodies are then secondary sealed with insulating resin 50. More specifically, the side surfaces of the solid electrolytic capacitor 1 body (the surfaces cut along cutting lines S11 and S12 (the upper surface, lower surface, and side surfaces other than the end surfaces where the anode electrode 11 and cathode electrode 20 are exposed)) are covered with secondary sealing with insulating resin 50. This allows the anode electrode 11 and cathode electrode 20, which would otherwise be unnecessarily exposed during singulation, to be covered with insulating resin 50.

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

Next, each step will be explained in more detail.

(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-state.

The anode electrode 11 is subjected to chemical conversion treatment to form the dielectric layer 12 (Figure 6: S111). During this process, numerous holes are formed on the surface of the anode electrode 11 by etching, making the area near the surface of the anode electrode 11 porous. The dielectric layer 12 covers the surface of the anode electrode 11, including the inner surfaces of the holes.

Next, anode through holes are formed in the anode electrode 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 electrode 11. The cylindrical anode through holes 19C and groove-shaped anode through holes 19L are alternately arranged along the direction in which the portions that will become the anode electrodes 11 are arranged. The cylindrical anode through holes 19C are formed at positions that will form the first ends 10E1 of the anode electrodes 11, and the groove-shaped anode through holes 19L are formed at positions that straddle the portions that will become adjacent anode electrodes 11 and at positions that will form the second ends 10E2 of the adjacent anode electrodes 11.

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, a CP layer 13 (a laminated structure of an inner layer CP 131 and an outer layer CP 132) is formed within the opening of the first dam 14.

This structure is implemented in a multi-state, as shown in Figure 8, in which multiple 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.

(Cathode electrode sheet forming process)
FIG. 9 is a perspective view showing the appearance of the cathode electrode before being divided into individual pieces.

As shown in FIG. 9 , the cathode electrode 20 has a plurality of cylindrical cathode through holes 29C and groove-shaped cathode through holes 29L formed therein. The cylindrical cathode through holes 29C and groove-shaped cathode through holes 29L are arranged alternately 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 the 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 the second ends 20E2 of the adjacent cathode electrodes 20.

(Sheet laminate 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 a second dam has been formed on a capacitor element sheet, with FIG. 11(A) showing the multi-layer structure and FIG. 11(B) showing a portion of a single capacitor element. FIG. 12 is an external perspective view showing a state in which a second dam and an adhesive have been formed on a capacitor element sheet, with FIG. 12(A) showing the multi-layer structure and FIG. 12(B) showing a 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.

A second dam 30 is formed on the sheet stack (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 in 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 it has a shape that extends inside the inner frame of the first dam 14 during heating and pressurization, as described below.

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

Next, as shown in Figures 12(A) and 12(B), adhesive 40 is placed inside the opening of the second dam 30 (Figure 10: S122).

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

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 with 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.

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

In addition, this heating and pressurizing process closes the dam adjustment 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 for a low-profile sheet laminate.

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.

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 similar parts will be omitted.

As shown in Figure 16 (B), the cathode electrode 20A has a third dam 210. Like the second dam 30, the third dam 210 is made of an insulating material such as insulating resin.

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, contact between the adhesive 40 and the anode electrode 11 can be prevented. The presence of the third dam 210 further prevents the adhesive 40 from spreading outward from the cathode electrode 20A.

(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.

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

The anode electrode 11 is preferably flat, and the thickness of the core portion of the anode electrode 11 (the center portion not reached by the pores of the porous body) is preferably 5 μm or more and 100 μm or less. The thickness (thickness on 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.

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.

The inner layer CP131 may be a PEDOT:PSS layer, realized, for example, by a conductive polymer with a skeleton of pyrroles, thiophenes, anilines, etc., or a conductive polymer with a skeleton of thiophenes, such as PEDOT [poly(3,4-ethylenedioxythiophene)], and composited with the dopant polystyrene sulfonic acid (PSS). The inner layer CP131 may be formed, for example, by a method using a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene to form a polymer film such as poly(3,4-ethylenedioxythiophene) on the surface of the dielectric layer 12, 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.

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.

The adhesive 40 may be a mixture of insulating resin such as epoxy resin or phenolic resin and conductive particles such as carbon or silver. The adhesive 40 may also be a dispersion of a conductive polymer, or a dispersion of a conductive polymer with a binder added.

The cathode electrode 20 is formed 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 should be as thin as possible, approximately 5 μm to 50 μm, and preferably approximately 30 μm.

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 a phenol resin is more preferable.

BD...boundary portion d...distance 1, 1A...solid electrolytic capacitor 10...capacitor element 10E1, 20E1...first end 10E2, 20E2...second end 11...anode electrode 12...dielectric layer 14...first dam 14P...inner periphery portion 19C, 19L...anode through-hole 20, 20A...cathode electrode 29C, 29L...cathode through-hole 30...second dam 30L...dam adjustment portion 30P...inner periphery portion 40...adhesive 50...insulating resin 61, 62...external electrode 100...capacitor element laminate 131...inner layer CP
132...Outer layer CP
210...Third Dam

Claims (5)

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. The solid electrolytic capacitor described in claim 1, wherein the second dam has a dam adjustment portion where no dam material is formed. 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 . 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. 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.