Solid electrolytic capacitors

Abstract

This solid electrolytic capacitor comprises a sheet laminate and an insulating resin. The sheet laminate is formed by alternately laminating a plurality of flat-film capacitor elements and a plurality of flat-film electrode foils for a negative electrode with conductive sheet layers therebetween. The insulating resin seals the sheet laminate. The flat-film capacitor element comprises: a flat-film electrode foil for a positive electrode; a dielectric layer formed on the surface of the electrode foil for a positive electrode; and a solid electrolyte layer formed in a predetermined region on the surface of the dielectric layer. The conductive sheet layer has a plurality of conductive fillers, and has a plurality of locations in which the current vector changes between the flat-film capacitor element and the flat-film electrode foil for a negative electrode.

Description

Technical Field

[0001] The present invention relates to a solid electrolytic capacitor including a laminate in which a plurality of capacitor elements are laminated.

Background Art

[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 solid electrolyte layer, and a cathode layer including a carbon layer, a conductive paste layer, and a conductive polymer layer. The conductive polymer layer joins carbon particles of the carbon layer and metal conductive particles of the conductive paste layer.

[0003] Further, Patent Document 2 describes a solid electrolytic capacitor. The solid electrolytic capacitor described in Patent Document 2 includes a solid electrolyte layer, a carbon cathode layer, and a metal cathode layer. The metal cathode layer is formed of at least two layers. The metal particle diameter of the metal cathode layer other than the innermost layer in the metal cathode layer is larger than the metal particle diameter of the metal cathode layer in the innermost layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the solid electrolytic capacitor configurations shown in Patent Documents 1 and 2, a carbon layer is used between the cathode lead layer (cathode foil) and the conductive polymer layer to improve adhesive strength. However, as the number of stacked capacitor elements constituting the solid electrolytic capacitor increases, the magnetic field generated between the conductive polymer layer and the cathode lead layer (cathode foil) increases. More specifically, since the direction of the current flowing in the normal direction in the capacitor element is constant, the magnetic field is not canceled out. Therefore, because the magnetic field increases, the ESL of the capacitor element increases. In other words, it is affected by the inductance in the high-frequency range, and the desired characteristics may not be obtained.

[0006] Therefore, an object of the present invention is to provide a solid electrolytic capacitor that can suppress the increase in ESL even when the number of stacked capacitor elements is increased. [Means for solving the problem]

[0007] The solid electrolytic capacitor of this invention comprises a sheet laminate and an insulating resin. The sheet laminate is formed by alternately stacking a plurality of flat film capacitor elements and a plurality of flat film cathode electrode foils with conductive sheet layers in between. The insulating resin seals the sheet laminate.

[0008] The flat film capacitor element comprises a flat film anode electrode foil, a dielectric layer formed on the surface of the anode electrode foil, and a solid electrolyte layer formed within a predetermined region on the surface of the dielectric layer. The conductive sheet layer has multiple conductive fillers and has multiple locations where the current density changes between the flat film capacitor element and the flat film cathode electrode foil.

[0009] This configuration allows for diverse current densities within the conductive sheet layer. In other words, the magnitude and direction of the magnetic field generated by the current flowing through the conductive sheet become more complex. As a result, the magnetic fields cancel each other out, reducing the magnetic field strength. That is, the ESL (Electromagnetic Saturation Level) decreases.

[0010] The solid electrolytic capacitor of this invention comprises a sheet laminate and an insulating resin. The sheet laminate is formed by alternately stacking a plurality of flat film capacitor elements and a plurality of flat film cathode electrode foils with conductive sheet layers in between. The insulating resin seals the sheet laminate.

[0011] A flat film capacitor element comprises a flat film anode electrode foil, a dielectric layer formed on the surface of the anode electrode foil, and a solid electrolyte layer formed within a predetermined region on the surface of the dielectric layer. The conductive sheet layer contains a plurality of conductive fillers in a resin layer.

[0012] This configuration allows for diverse current densities within the conductive sheet layer. In other words, the magnitude and direction of the magnetic field generated by the current flowing through the conductive sheet become more complex. As a result, the magnetic fields cancel each other out, reducing the magnetic field strength. That is, the ESL (Electromagnetic Saturation Level) decreases. [Effects of the Invention]

[0013] This invention provides a solid electrolytic capacitor that can suppress the increase in ESL even when the number of stacked capacitor elements is increased. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to the first embodiment. [Figure 2] Figure 2(A) is a side cross-sectional view showing the configuration of the capacitor element and conductive sheet layer set before individualization, and Figure 2(B) is a side cross-sectional view showing the configuration of the capacitor element and conductive sheet layer set after individualization. [Figure 3] Figure 3 is a side cross-sectional view showing an overview of the structure of a capacitor element. [Figure 4] Figure 4 is a side cross-sectional view modeling the structure of the conductive sheet layer. [Figure 5] Figure 5 shows the electric field vector in the conductive sheet layer. [Figure 6] FIG. 6 is a contour diagram of the electric field distribution in the conductive sheet layer. [Figure 7] FIG. 7 is a graph showing the inspection target area of the solid electrolytic capacitor according to the first embodiment. [Figure 8] is a flowchart showing an example of a schematic flow of the method for manufacturing a solid electrolytic capacitor according to the first embodiment. [Figure 9] FIG. 9 is a flowchart showing an example of the process for forming the capacitor element sheet. [Figure 10] FIG. 10(A) is an external perspective view showing the shape of the electrode of the capacitor element before singulation, and FIG. 10(B) is an external perspective view showing the shape of the capacitor element before singulation. [Figure 11] FIG. 11 is a flowchart showing an example of the process for forming the sheet laminate. [Figure 12] FIG. 12(A) is an exploded perspective view showing the state of laminating the capacitor element sheet, the conductive sheet layer 15, and the cathode electrode 20, and FIG. 12(B) is an external perspective view of the solid electrolytic capacitor 1 in the multi-state. [Figure 13] FIG. 13 is a side cross-sectional view showing an outline of the structure of the capacitor element according to the second embodiment. [Figure 14] FIG. 14 is a side cross-sectional view showing the configuration of the capacitor element and the cathode electrode according to the third embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] [First Embodiment] A solid electrolytic capacitor according to the first embodiment of the present invention, and a method for manufacturing this solid electrolytic capacitor will be described with reference to the drawings.

[0016] (Explanation of the schematic 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. Figure 1 is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to the first embodiment. Note that in Figure 1, only the insulating resin, external electrodes, and conductive sheet layer are hatched for clarity. Figure 2(A) is a side cross-sectional view showing the configuration of the capacitor element and conductive sheet layer set before individualization, and Figure 2(B) is a side cross-sectional view showing the configuration of the capacitor element and conductive sheet layer set after individualization.

[0017] As shown in Figure 1, the solid electrolytic capacitor 1 comprises a capacitor element laminate 100, an insulating resin 50, an external electrode 61, and an external electrode 62. The capacitor element laminate 100 comprises a plurality of flat film capacitor elements 10 and a plurality of flat film cathode electrodes 20. In Figure 1, the number of flat film capacitor elements 10 and cathode electrodes is 4 each, but it is not limited to this. The cathode electrode 20 corresponds to the "cathode electrode foil" in this invention. The side cross-sectional views in Figures 1, 2(A), and 2(B) are cross-sectional views of the capacitor element laminate 100 in Figure 1 taken from planes perpendicular to the top surface 101 and bottom surface 102.

[0018] As shown in Figure 2(A), the capacitor element 10 comprises a flat film electrode 11, a dielectric layer 12, and a CP layer (solid electrolyte layer) 13.

[0019] Although detailed structural illustrations are omitted in Figures 2(A) and 2(B), the electrode 11 has numerous pores. In other words, the electrode 11 is porous. The ratio of the thickness of the porous portion on one side of the 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 electrode 11. Since detailed structural illustrations of the electrode 11 are omitted in Figures 2(A) and 2(B), the dielectric layer 12 is schematically shown as covering the macroscopic surface of the electrode 11. In reality, the dielectric layer 12 covers not only the macroscopic surface of the electrode 11 but also the surfaces of the numerous pores in the electrode 11.

[0020] The CP layer 13 covers the surface of the dielectric layer 12. The CP layer 13 is formed inside a frame-shaped dam 14. The dam 14 is insulating. The dam 14 restricts the area where the CP layer 13 is formed. In the first embodiment, as described in the manufacturing method later, the CP layer 13 is formed inside the dam 14 after the dam 14 has been formed in a frame shape. However, depending on the manufacturing method of the capacitor element 10, such as when the capacitor element 10 is manufactured in individual pieces from the beginning, the dam 14 does not have to be formed in a frame shape. That is, the dam 14 may be formed on one side, or on two sides with corners. Furthermore, it may be a structure in which it is formed on two opposing sides in a plan view. If the CP layer can be formed only on the surface of the dielectric layer 12, the dam 14 may be omitted.

[0021] The CP layer 13 has a laminated structure consisting of an inner CP (inner solid electrolyte layer) 131 and an outer CP (outer solid electrolyte layer) 132. The inner CP 131 is formed on the surface of the dielectric layer 12, and the outer CP 132 is formed on the surface of the inner CP 131.

[0022] Multiple capacitor elements 10 and multiple cathode electrodes 20 are stacked alternately so that their respective flat film surfaces are parallel and overlap when viewed from above.

[0023] A conductive sheet layer 15 is placed between adjacent capacitor elements 10 and cathode electrodes 20. The detailed structure of the conductive sheet layer 15 will be described later.

[0024] In this stacked configuration, the first ends 10E1 (see Figure 2(B)) of the multiple capacitor elements 10 are located at approximately the same position when viewed from the side. Similarly, the second ends 10E2 (see Figures 1 and 2(B)) of the multiple capacitor elements 10 are located at approximately the same position when viewed from the side. Furthermore, the first ends 20E1 (see Figures 1 and 2(B)) of the multiple cathode electrodes 20 are located at approximately the same position when viewed from the side. Similarly, the second ends 20E2 (see Figures 1 and 2(B)) of the multiple cathode electrodes 20 are located at approximately the same position when viewed from the side.

[0025] The first ends 10E1 of the multiple capacitor elements 10 and the second ends 20E2 of the multiple cathode electrodes 20 are positioned 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.

[0026] The second ends 10E2 of the multiple capacitor elements 10 and the first ends 20E1 of the multiple cathode electrodes 20 are positioned on the second end side of the capacitor element stack 100. The first ends 20E1 of the multiple cathode electrodes 20 protrude outward from the second ends 10E2 of the multiple capacitor elements 10.

[0027] The capacitor element stack 100 is realized through this structure.

[0028] The capacitor element laminate 100 is sealed with an insulating resin 50. More specifically, as shown in Figure 1, the insulating resin 50 covers the capacitor element laminate 100 except for the first ends 10E1 of the multiple capacitor elements 10 (the first ends 10E1 of the electrodes 11) and the first ends 20E1 of the multiple cathode electrodes 20.

[0029] The external electrode 61 covers the first end (the first end 10E1 of the electrode 11) of the insulating resin 50. The external electrode 61 is connected to the first end 10E1 of the electrodes 11 of the multiple capacitor elements 10.

[0030] 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 end 20E1 of the multiple cathode electrodes 20.

[0031] The solid electrolytic capacitor 1 is realized with the above configuration.

[0032] (Detailed description of the conductive sheet layer 15 in the solid electrolytic capacitor 1) Next, the detailed structure of the conductive sheet layer 15 in the solid electrolytic capacitor 1 will be explained using Figure 3. Figure 3 is a schematic side cross-sectional view showing the structure of the capacitor element 10 and the conductive sheet layer 15, and is an enlarged view of the structure of the capacitor element 10 in Figure 2(A) described above. In Figure 3, the structure of one main surface on which the conductive sheet layer 15 and cathode electrode 20 are arranged on the capacitor element 10 will be explained, but the other main surface opposite the first main surface has a similar structure. The side cross-sectional view in Figure 3 is a cross-sectional view taken by planes perpendicular to the top surface 101 and bottom surface 102 of the capacitor element stack 100 in Figure 1.

[0033] Note that, for the sake of clarity in the explanation, each structure is enlarged and exaggerated in the representation. Also, although Figure 3 shows only one set of capacitor element 10 and cathode electrode 20, the solid electrolytic capacitor 1 is formed by stacking multiple such sets.

[0034] The conductive sheet layer 15 comprises a conductive filler 151 and a resin layer 152. In other words, the conductive sheet layer 15 is formed of a resin layer 152, and the conductive filler 151 is surrounded by this resin layer 152.

[0035] The conductive filler 151 has an irregular shape. For example, the conductive filler 151 may be a sphere, a polygonal prism, an elongated sphere, or an oblate ellipsoid. In other words, the outer shape of the conductive filler 151 may be rounded or pointed. Furthermore, the surface of the conductive filler 151 may have an uneven shape or it may be flat without any unevenness.

[0036] As shown in Figure 3, the conductive filler 151 is arranged in the resin layer 152 at arbitrary intervals. That is, the conductive sheet layer 15 is a region where the conductive filler 151 and the resin layer 152 are mixed. Note that the conductive sheet layer 15 has a bottom surface 104 on the side facing the bottom surface 102 in Figure 1, and a top surface 103 on the side facing the top surface 101 in Figure 1.

[0037] Next, the structure of the conductive filler 151 and resin layer 152 along the straight line (AB line) connecting an arbitrary point A on the bottom surface 104 of the conductive sheet layer 15 to an arbitrary point B on the top surface 103 of the sheet will be described. The direction of this AB line corresponds to the "normal direction" in this invention.

[0038] Along the AB line, the structure of the conductive sheet layer 15 changes four times in the order of resin layer 152, conductive filler 151, resin layer 152, conductive filler 151, and resin layer 152. In other words, in the conductive sheet layer 15, the structure of the conductive filler 151 and resin layer 152 changes four times aperiodically from point A to point B.

[0039] Because the conductive sheet layer 15 has a structure containing conductive filler 151, the current vector of the current entering point B from point A changes irregularly. As a result, the potential gradient in the conductive sheet layer 15 becomes complex, and the current density becomes non-uniform. In other words, the magnitude and direction of the magnetic field generated by the current become complex, causing the magnetic fields to cancel each other out. Therefore, the magnetic field is reduced, and the increase in ESL can be suppressed.

[0040] In this case, when viewing the conductive sheet layer 15 in the direction normal to it, it is preferable that the number of times the conductive filler 151 and resin layer 152 are changed is at least 2. More preferably, it is preferable that it is 4 or more times. The number of times the conductive filler 151 and resin layer 152 are changed is preferably as many as possible in accordance with Ampere's law. That is, the proportion (concentration) of conductive filler 151 contained in the resin layer 152 is, for example, on average 30% to 85% inside the conductive sheet layer 15, preferably 60% to 80%. This increases the effect of canceling out the generated magnetic field. Furthermore, if the conductive sheet layer 15 contains at least 30% conductive filler 151, an effect of canceling out a certain magnetic field can be obtained. The proportion (concentration) of conductive filler 151 contained in the resin layer 152 is the proportion of the cross-sectional area occupied by conductive filler 151 when the cross-sectional area of ​​the resin layer 152 is set to 100, when a cross-sectional observation of the center of the capacitor element 10 is performed.

[0041] However, if a large amount of conductive filler 151 is included (the concentration of conductive filler 151 in the conductive sheet layer 15 is high), the conductive sheet layer 15 will approach that of a single metal layer. In other words, it becomes difficult to obtain the effect of electric field anisotropy, so it is preferable not to include too much, taking into account the ESR of the conductive sheet layer 15.

[0042] (Explanation of the conceptual structure of the conductive sheet layer 15) Next, the conceptual structure of the conductive sheet layer 15 will be explained using Figures 4, 5, and 6. Figure 4 is a side cross-sectional view modeling the structure of the conductive sheet layer 15. Figure 5 is a diagram showing the electric field vector in the conductive sheet layer 15. Figure 6 is a contour diagram of the electric field distribution in the conductive sheet layer 15. Note that in Figures 4, 5, and 6, hatching of the resin layer 152 has not been performed for clarity. Note that the units and numerical values ​​of the current vectors in Figures 5 and 6 are examples only and are not limited to this description. Also, in Figure 4, the direction of the current is shown macroscopically, and in Figure 5, the electric field vector (magnitude and direction of the current) is shown macroscopically.

[0043] Figures 4, 5, and 6 are conceptual diagrams showing the side cross-sectional view shown in Figure 3. As shown in Figure 4, multiple conductive fillers 151 are present in the resin layer 152. In this state, current is passed from the bottom surface 104 of the sheet to the top surface 103 of the sheet. As a result, a current vector is generated as a whole from the bottom surface 104 of the sheet to the top surface 103 of the sheet. At this time, near the bottom surface 104 of the sheet, the current vector is perpendicular to the bottom surface 104 of the sheet. A magnetic field is generated according to this current vector.

[0044] Here, we compare the configuration of the present invention with a conventional configuration. In the conventional configuration in which the conductive sheet layer of the present invention does not contain the conductive filler 151, current vectors perpendicular to the sheet bottom surface 104 and the sheet top surface 103 are generated. That is, the current vectors are not canceled out and are generated in the direction from the sheet bottom surface 104 to the sheet top surface 103. Therefore, the magnetic field is not canceled out.

[0045] However, in the configuration of the present invention, a conductive filler 151 is present in the conductive sheet layer 15. That is, as shown in Figure 5, the magnitude and direction of the current vector perpendicular to the sheet bottom surface 104 become more complex due to the presence of this conductive filler 151. Consequently, as shown in Figure 6, the potential gradient also becomes more complex. As a result, the magnetic fields generated in the conductive sheet layer 15 cancel each other out, and the magnetic field is reduced. That is, the ESL decreases. Therefore, when using the configuration of the present invention, the ESL can be reduced, and the inductor component that becomes reactance in the high-frequency region is reduced.

[0046] Here, the specific effects of the present invention will be explained using an example of resistance testing (film deposition quality, interfacial delamination) of a solid electrolytic capacitor. Figure 7 is a graph showing the inspection area of ​​a solid electrolytic capacitor according to the first embodiment. In Figure 7, the solid line shows the reactance due to ESL. In this resistance test, the quality of the external electrodes is inspected. In resistance testing of the external electrodes of a solid electrolytic capacitor, detection on the order of sub-milliohms is required in the frequency range above 1 MHz. This is, for example, the shaded area shown in the graph of Figure 7. Note that the units and values ​​of frequency and impedance in Figure 7 are examples only and are not limited to this description.

[0047] In conventional configurations, due to the influence of ESL (which increases the reactance at high frequencies), it was not possible to accurately test the resistance of the external electrodes in the high-frequency range (the shaded area shown in Figure 7).

[0048] However, by using the configuration of the present invention, the inductive component that becomes reactance in the high-frequency range is reduced. For example, in Figure 7, the conventional configuration is represented by the top solid line, but by using the configuration of the present invention, it can be reduced to the bottom solid line. Therefore, at 1 MHz, the reactance can be made lower than 1.0 mΩ.

[0049] Therefore, it is possible to detect the resistance component in the high-frequency range. In other words, the ESR of the external electrodes of a solid electrolytic capacitor can be accurately inspected.

[0050] As described above, since the ESR of the external electrodes can be accurately inspected, it is possible to suppress defects (such as broken wires) that originate from the quality of the external electrodes. Therefore, it becomes possible to achieve long-term reliability of solid electrolytic capacitors.

[0051] Furthermore, this configuration eliminates the need for an adhesive carbon layer. This suppresses the ESR caused by the carbon layer. Therefore, the solid electrolytic capacitor 1 can have a low ESR.

[0052] (Manufacturing method for solid electrolytic capacitor 1) The solid electrolytic capacitor 1 having the above configuration is manufactured, for example, as follows. Figure 8 is a flowchart showing an example of a schematic flow of the manufacturing method of a solid electrolytic capacitor according to the first embodiment.

[0053] A capacitor element sheet is formed (Figure 8: S11). The capacitor element sheet is formed with multiple capacitor elements 10 arranged in a grid, each forming a different solid electrolytic capacitor 1.

[0054] Next, capacitor element sheets are stacked to form a sheet stack (Figure 8: S12). This creates a structure in which multiple capacitor element stacks 100 are arranged in a planar manner. In other words, a sheet stack is a structure in which multiple capacitor element stacks 100 are arranged in a planar manner.

[0055] Next, the sheet laminate is sealed with insulating resin 50 (Figure 8: S13). As will be described in detail later, at this time, a through hole is provided in the sheet laminate that penetrates from the top surface to the bottom surface, and resin sealing is performed by compression molding.

[0056] The sealing with the insulating resin 50 is performed while the solid electrolytic capacitor 1 is in a multi-state (a state in which multiple solid electrolytic capacitors 1 are arranged together) before it is separated into individual pieces.

[0057] Next, the sheet laminate sealed with insulating resin 50 is cut and separated into individual pieces (Figure 8: S14). Specifically, the cutting is performed along a cutting line formed at an arbitrary position. This creates multiple solid electrolytic capacitors 1 (referred to as solid electrolytic capacitor 1 bases) without external electrodes. After this, the solid electrolytic capacitor 1 bases are subjected to secondary sealing with insulating resin 50. More specifically, the sides of the solid electrolytic capacitor 1 bases are covered with secondary sealing of insulating resin 50. This covers the electrodes 11 of the capacitor element 10 that are unnecessarily exposed during the separation into individual pieces with insulating resin 50.

[0058] Next, external electrodes 61 and 62 are formed on the end face of the solid electrolytic capacitor 1 (Figure 8: S15).

[0059] Next, we will explain each step in more detail.

[0060] (Formation process of capacitor element sheet) Figure 9 is a flowchart showing an example of the capacitor element sheet formation process. Figure 10(A) is an external perspective view showing the shape of the electrodes of the capacitor element before individualization, and Figure 10(B) is an external perspective view showing the shape of the capacitor element before individualization. Figure 11 is a flowchart showing an example of the sheet laminate formation process.

[0061] A dielectric layer 12 is formed on the electrode 11 of the capacitor element 10 by chemical conversion treatment (Figure 9: S111). At this time, numerous holes are formed on the surface of the electrode 11 by etching, and the area near the surface of the electrode 11 becomes porous. The dielectric layer 12 covers the surface of the electrode 11, including the inner surfaces of the holes.

[0062] Next, through holes are formed in the electrode 11 (Figure 9: S112). More specifically, as shown in Figure 10(A), multiple cylindrical through holes 19C and groove-shaped through holes 19L are formed in the electrode 11. The multiple cylindrical through holes 19C and groove-shaped through holes 19L are arranged alternately along the direction in which the portions that will become the electrodes 11 are aligned.

[0063] Similarly, as shown in Figures 12(A) and 12(B) described later, the cathode electrode 20 also has a through hole 29C corresponding to the through hole 19C and a through hole 29L corresponding to the groove-shaped through hole 19L.

[0064] Next, a CP layer (solid electrolyte layer) 13 is formed on the surface of the dielectric layer 12 (Figure 9: S113). More specifically, as shown in Figure 10(B), a dam 14 with a frame-shaped opening is formed so as not to block the anode through-holes (through-holes 19C and 19L). Then, the CP layer 13 (a laminated structure of inner layer CP131 and outer layer CP132) is formed within the opening of the dam 14.

[0065] This structure is carried out in a multi-state configuration, as shown in Figure 12(A), in which multiple capacitor elements 10 (structures consisting of electrodes 11, dielectric layers 12, CP layers 13, and dams 14) are arranged in two dimensions. Cutting is performed along the cutting lines for forming the solid electrolytic capacitor 1. This creates multiple solid electrolytic capacitors 1 (referred to as the basic bodies of the solid electrolytic capacitor 1) in a state where no external electrodes have been formed.

[0066] In the above configuration, step S112 shows the formation of anode through-holes (through-holes 19C and 19L), followed by the formation of the dam 14 in step S113. However, the process may also involve forming the dam 14 first, followed by the formation of the anode through-holes (through-holes 19C and 19L).

[0067] (Formation process of sheet laminate) Figure 11 is a flowchart showing an example of the sheet laminate formation process. Figure 12(A) is an exploded perspective view showing the state in which the capacitor element sheet, the conductive sheet layer 15, and the cathode electrode 20 are laminated, and Figure 12(B) is an external perspective view of the solid electrolytic capacitor 1 in its multi-layer state.

[0068] As shown in Figure 12(A), the capacitor element sheet, the conductive sheet layer 15, and the cathode electrode 20 are stacked alternately (Figure 11: S121).

[0069] These through-holes are formed in multiples depending on the number of capacitor elements arranged in the sheet laminate. Therefore, multiple through-holes are formed in the sheet laminate that penetrate from the top surface to the bottom surface of the sheet laminate.

[0070] Next, the sheet laminate is heated and pressurized (Figure 11: S122). This causes the capacitor element sheet, the conductive sheet layer 15, and the cathode electrode 20 to bond together, forming the sheet laminate. In other words, the capacitor element sheet and the cathode electrode 20 are bonded together by the conductive sheet layer 15 as described above.

[0071] [Second Embodiment] Next, a solid electrolytic capacitor according to the second embodiment will be described with reference to the figures. Figure 13 is a side cross-sectional view showing the configuration of the solid electrolytic capacitor according to the second embodiment.

[0072] As shown in Figure 13, the solid electrolytic capacitor 1A according to the second embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in the structure of the conductive sheet layer 15A. The other components of the solid electrolytic capacitor 1A are the same as those of the solid electrolytic capacitor 1, and a description of the similar parts will be omitted.

[0073] The conductive sheet layer 15A comprises a filler 151A and a resin layer 152. The filler 151A comprises, for example, resin particles 153. The surface of the resin particles 153 is covered with a metal film 154. The metal film 154 can be silver, copper, aluminum, or the like.

[0074] Even with this configuration, the current vector of the current entering point B from point A changes irregularly, similar to the conductive sheet layer 15 in the first embodiment. As a result, the potential gradient in the conductive sheet layer 15A becomes complex, and the current density becomes non-uniform. In other words, the magnitude and direction of the magnetic field generated by the current become complex, causing the magnetic fields to cancel each other out. Therefore, the magnetic field is reduced, and the increase in ESL can be suppressed.

[0075] In the conductive sheet layer 15A, only the surface of the filler 151A is covered with a conductive metal film 154. That is, the resistance is higher compared to the conductive filler 151 in the first embodiment. However, the material cost can be reduced compared to using the conductive filler 151.

[0076] [Third Embodiment] Next, a solid electrolytic capacitor according to the third embodiment will be described with reference to the figures. Figure 14 is a side cross-sectional view showing the configuration of the solid electrolytic capacitor according to the third embodiment.

[0077] The solid electrolytic capacitor 1B according to the third embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in that it includes a carbon layer 16. The other components of the solid electrolytic capacitor 1B are the same as those of the solid electrolytic capacitor 1, and a description of the similar parts will be omitted.

[0078] As shown in Figure 14, a carbon layer 16 is formed between the outer layer CP132 and the conductive sheet layer 15. This configuration improves the adhesive strength between the capacitor element 10 and the cathode electrode 20.

[0079] Even with this configuration, the current vector of the current entering point B from point A changes irregularly, similar to the conductive sheet layer 15 in the first embodiment. As a result, the potential gradient in the conductive sheet layer 15 becomes complex, and the current density becomes non-uniform. That is, the magnitude and direction of the magnetic field generated by the current become complex, causing the magnetic fields to cancel each other out. Therefore, the magnetic field is reduced, and the increase in ESL can be suppressed. Furthermore, by including the carbon layer 16, the adhesive strength inside the solid electrolytic capacitor 1B can be further improved.

[0080] Furthermore, the carbon layer 16 may be annular in shape following the outer shape of the outer layer CP132, or it may be formed only at the ends of the outer layer CP132. In other words, the solid electrolytic capacitor 1B can be configured to increase the contact area between the conductive sheet layer 15 and the cathode electrode 20 while still having a carbon layer 16. This makes it possible to reduce the ESR and improve the contact strength compared to the configuration of the first embodiment.

[0081] Furthermore, the carbon layer 16 may be partially formed near the center when the outer layer CP132 is viewed in plan. In other words, the carbon layer 16 does not need to be formed over the entire surface of the outer layer CP132; a configuration in which the carbon layer 16 is provided in at least a part of it is sufficient.

[0082] (Explanation of specific materials and other examples for each component of solid electrolytic capacitor 1) (Capacitor element) The capacitor element 10 can be realized using, for example, the following materials and thicknesses.

[0083] The electrode 11 is made of, for example, a single metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, or copper, or an alloy containing these metals. Preferably, the electrode 11 is aluminum or an aluminum alloy. The electrode 11 can be any valve-acting metal that exhibits so-called valve action.

[0084] The electrode 11 is preferably flat, and the thickness of the core portion of the electrode 11 (the central part not reached by the pores of the porous material) is preferably 5 μm or more and 100 μm or less. The thickness of the porous portion (the portion where the pores of the porous material are formed) (thickness on one side) is preferably 5 μm or more and 200 μm or less.

[0085] The dielectric layer 12 is preferably made of an oxide film of the electrode 11. For example, when aluminum foil is used for the electrode 11, the dielectric layer 12 is formed by oxidation in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or their sodium salts, ammonium salts, etc. The thickness of the dielectric layer 12 is preferably 1 nm or more and 100 nm or less.

[0086] The inner layer CP131 may be realized using, for example, a conductive polymer with a backbone of pyrroles, thiophenes, anilines, etc., or a conductive polymer with a backbone of thiophenes such as PEDOT [poly(3,4-ethylenedioxythiophene)], and may be a PEDOT:PSS layer compounded with polystyrene sulfonic acid (PSS) as a dopant. The inner layer CP131 is formed, for example, by a method of forming a polymerized film of poly(3,4-ethylenedioxythiophene) on the surface of the dielectric layer 12 using a processing solution 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 part and drying it.

[0087] 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. However, the material of the outer layer CP132 may be different from the material of the inner layer CP131. In this case, for example, the inner layer CP131 can be formed with PEDOT:PSS and the outer layer CP132 can be formed with polypyrrole.

[0088] The insulating resin 50 may contain fillers. Preferred resins include, for example, epoxy resins, phenolic resins, polyimide resins, silicone resins, polyamide resins, and liquid crystal polymers. Preferred fillers include, for example, insulating oxide particles such as silica particles, alumina particles, titania particles, and zirconia particles. The maximum diameter of the fillers is preferably, for example, 10 μm or more and 50 μm or less. For example, it is more preferable that the material contains silica particles in a solid epoxy resin and a phenolic resin.

[0089] (Conductive sheet layer) The resin layer 152 in the conductive sheet layer 15 is preferably a thermosetting resin (epoxy resin). Alternatively, if a certain degree of flexibility is required, a thermosetting resin may also be used.

[0090] The correspondence between the configuration of this invention and the configuration described above is described below. [Note] <1> A sheet laminate formed by alternately stacking multiple flat film capacitor elements and multiple flat film cathode electrode foils with a conductive sheet layer in between, An insulating resin that seals the aforementioned sheet laminate, Equipped with, The aforementioned flat film capacitor element is A flat film-shaped anode electrode foil, A dielectric layer formed on the surface of the anode electrode foil, A solid electrolyte layer formed within a predetermined region on the surface of the dielectric layer, Equipped with, The conductive sheet layer has a plurality of conductive fillers, and there are a plurality of locations between the flat film capacitor element and the flat film cathode electrode foil where the current density changes, in this solid electrolytic capacitor.

[0091] <2> The conductive sheet layer is When the flat film cathode electrode is viewed from the flat film capacitor element in the direction normal to the capacitor element, The filler comprises one or more of the above fillers, <1> Solid electrolytic capacitors as described above.

[0092] <3> The conductive sheet layer is When the flat film cathode electrode is viewed from the flat film capacitor element in the direction normal to the electrode, the number of fillers is two or less. <1> or <2> Solid electrolytic capacitors as described above.

[0093] <4> The aforementioned filler consists of a metal component. <1> or <2> Solid electrolytic capacitors as described above.

[0094] <5> The filler has a resin base, The surface of the resin is covered with a metal film. <1> or <2> Solid electrolytic capacitors as described above.

[0095] <6> A carbon layer is provided between the flat film capacitor element and the conductive sheet layer. <1> ~ <3> A solid electrolytic capacitor as described in any of the following.

[0096] <7> The solid electrolyte is formed within a region restricted by a dam formed on the surface of the dielectric layer. <1> Solid electrolytic capacitors as described above.

[0097] <8> A sheet laminate formed by alternately stacking multiple flat film capacitor elements and multiple flat film cathode electrode foils with a conductive sheet layer in between, An insulating resin that seals the aforementioned sheet laminate, Equipped with, The aforementioned flat film capacitor element is A flat film-shaped anode electrode foil, A dielectric layer formed on the surface of the anode electrode foil, A solid electrolyte layer formed within a predetermined region on the surface of the dielectric layer, Equipped with, A solid electrolytic capacitor wherein the conductive sheet layer is formed of a resin layer and the resin layer contains a plurality of conductive fillers.

[0098] <9> The filler is present in the resin layer at a rate of approximately 80 percent. <8> Solid electrolytic capacitors as described above.

[0099] <10> The solid electrolyte is formed within a region restricted by a dam formed on the surface of the dielectric layer. <9> Solid electrolytic capacitors as described above. [Explanation of Symbols]

[0100] 1, 1A, 1B… Solid electrolytic capacitors 10... Capacitor element 10E1,20E1…1st end 10E2,20E2…2nd end 11...Electrode 12…Dielectric layer 13…CP layer 14... Dam 15,15A…Conductive sheet layer 16…Carbon layer 19C,19L,29C,29L…Through hole 20...Cathode electrode 50…Insulating resin 61,62...External electrode 100... Capacitor element stack 101... Top surface 102...Bottom 103... Top surface of the seat 104...Bottom of the seat 131...Inner Layer CP 132...Outer layer CP 151... Conductive filler 151A... Filler 152… Resin layer 153… Resin particles 154…Metal film

Claims

1. A sheet laminate formed by alternately stacking multiple flat film capacitor elements and multiple flat film cathode electrode foils with a conductive sheet layer in between, An insulating resin that seals the aforementioned sheet laminate, Equipped with, The aforementioned flat film capacitor element is A flat film-shaped anode electrode foil, A dielectric layer formed on the surface of the anode electrode foil, A solid electrolyte layer formed within a predetermined region on the surface of the dielectric layer, Equipped with, A solid electrolytic capacitor in which the conductive sheet layer has a plurality of conductive fillers and has a plurality of locations between the flat film capacitor element and the flat film cathode electrode foil where the direction of the current vector changes.

2. The conductive sheet layer is When the flat film cathode electrode is viewed from the flat film capacitor element in the direction normal to the capacitor element, The solid electrolytic capacitor according to claim 1, comprising one or more of the fillers.

3. The conductive sheet layer is The solid electrolytic capacitor according to claim 1 or claim 2, wherein the number of fillers when viewed from the flat film capacitor element in the direction normal to the flat film cathode electrode is two or less.

4. The solid electrolytic capacitor according to claim 1 or claim 2, wherein the filler is made of a metal component.

5. The filler has a resin base, The solid electrolytic capacitor according to claim 1 or claim 2, wherein the surface of the resin is covered with a metal film.

6. The solid electrolytic capacitor according to claim 1, wherein a carbon layer is provided between the flat film capacitor element and the conductive sheet layer.

7. The solid electrolytic capacitor according to claim 1, wherein the solid electrolyte layer is formed within a region restricted by a dam formed on the surface of the dielectric layer.

8. A sheet laminate formed by alternately stacking multiple flat film capacitor elements and multiple flat film cathode electrode foils with a conductive sheet layer in between, An insulating resin that seals the aforementioned sheet laminate, Equipped with, The aforementioned flat film capacitor element is A flat film-shaped anode electrode foil, A dielectric layer formed on the surface of the anode electrode foil, A solid electrolyte layer formed within a predetermined region on the surface of the dielectric layer, Equipped with, The conductive sheet layer comprises a plurality of conductive fillers, forming a solid electrolytic capacitor.

9. The solid electrolytic capacitor according to claim 8, wherein the conductive sheet layer is made of a resin layer containing 30 to 85 percent of the filler.

10. The solid electrolytic capacitor according to claim 9, wherein the solid electrolyte layer is formed within a region restricted by a dam formed on the surface of the dielectric layer.

Images