Solid electrolytic capacitor element and solid electrolytic capacitor

Abstract

This solid electrolytic capacitor element 1 is provided with a valve-acting metal base material 10, an insulating mask layer 30, a solid electrolyte layer 40, a carbon layer 50 and a negative electrode conductor layer 60. The solid electrolyte layer 40 is arranged such that the front end thereof covers at least a part of the outer surface of the insulating mask layer 30; the carbon layer 50 is arranged such that the front end thereof covers the same portion of the outer surface of the insulating mask layer 30 as the front end of the solid electrolyte layer 40, or covers a portion that is closer to a negative electrode part 32 than the portion covered by the front end of the solid electrolyte layer 40; and the negative electrode conductor layer 60 is arranged such that the front end thereof covers a portion of the outer surface of the insulating mask layer 30, the portion being closer to the negative electrode part 32 than the portion covered by the front end of the carbon layer 50. The negative electrode part 32 comprises negative electrode conductor layer non-forming regions A1 and A2 in which the negative electrode conductor layer 60 does not cover a part of the carbon layer 50.

Description

[Technical field]

[0001] The present invention relates to a solid electrolytic capacitor element and a solid electrolytic capacitor. [Background technology]

[0002] Patent Document 1 discloses a solid electrolytic capacitor element having a solid electrolyte layer containing a conductive polymer provided on a dielectric oxide film formed on the surface of a valve metal having micropores, the solid electrolyte layer being characterized in that in a cross section of the capacitor element formed by overlapping a carbon paste layer and a highly conductive paste layer on the surface of the solid electrolyte layer, the solid electrolyte layer covers part of the outer surface on the cathode side of an insulating layer separating a cathode and an anode, and the highly conductive paste layer is formed on that surface up to a position spatially beyond the boundary of the cathode part of the insulating layer in the horizontal direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-267866 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to Patent Document 1, it is possible to reduce the equivalent series resistance without increasing leakage current defects in a solid electrolytic capacitor by adopting a structure in which (1) the solid electrolyte layer covers a part of the insulating layer formed on the outer surface of the valve action metal separating the anode and cathode, and (2) a highly conductive paste is applied so as to spatially exceed the boundary of the cathode part of the insulating layer formed on the outer surface of the valve action metal separating the anode and cathode.

[0005] Table 2 of Patent Document 1 shows that in the examples, a solid electrolyte layer is formed on the outer surface of the cathode side of the insulator layer, and a carbon paste layer and a highly conductive paste layer are further formed thereon, thereby reducing the equivalent series resistance. However, Table 1 of Patent Document 1 shows that there is no significant difference in leakage current between the examples and the comparative examples.

[0006] The present invention has been made to solve the above problems, and has an object to provide a solid electrolytic capacitor element having a low equivalent series resistance and little leakage current failure, and a solid electrolytic capacitor including the above solid electrolytic capacitor element. [Means for solving the problem]

[0007] The solid electrolytic capacitor element of the present invention comprises a valve metal base having a dielectric layer on at least one main surface thereof, an insulating mask layer provided on the dielectric layer and separating the valve metal base into an anode portion and a cathode portion, a solid electrolyte layer provided on the dielectric layer in the cathode portion, a carbon layer provided on the solid electrolyte layer, and a cathode conductor layer provided on the carbon layer. The solid electrolyte layer is provided such that a tip thereof covers at least a part of the outer surface of the insulating mask layer, the carbon layer is provided such that a tip thereof covers the same position as the tip of the solid electrolyte layer on the outer surface of the insulating mask layer or a position on the cathode portion side of the tip of the solid electrolyte layer, and the cathode conductor layer is provided such that a tip thereof covers a position on the outer surface of the insulating mask layer on the cathode portion side of the tip of the carbon layer. The cathode portion has a cathode conductor layer non-forming region in which the cathode conductor layer does not cover a part of the carbon layer.

[0008] The solid electrolytic capacitor of the present invention comprises a solid electrolytic capacitor element of the present invention, an exterior body that seals the solid electrolytic capacitor element, a first external electrode electrically connected to the valve metal base of the solid electrolytic capacitor element exposed from the exterior body, and a second external electrode electrically connected to the cathode conductor layer of the solid electrolytic capacitor element exposed from the exterior body. Effect of the Invention

[0009] According to the present invention, it is possible to provide a solid electrolytic capacitor element having a low equivalent series resistance and little leakage current failure, and further, it is possible to provide a solid electrolytic capacitor including the above solid electrolytic capacitor element. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a plan view illustrating an example of a solid electrolytic capacitor element according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line XX of the solid electrolytic capacitor element shown in FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line YY of the solid electrolytic capacitor element shown in FIG. [Figure 4] Fig. 4A is a plan view showing an example of a dielectric layer and an insulating mask layer constituting the solid electrolytic capacitor element shown in Fig. 1. Fig. 4B is a plan view showing an example of a dielectric layer, an insulating mask layer and a solid electrolyte layer constituting the solid electrolytic capacitor element shown in Fig. 1. Fig. 4C is a plan view showing an example of a dielectric layer, an insulating mask layer, a solid electrolyte layer and a carbon layer constituting the solid electrolytic capacitor element shown in Fig. 1. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a portion V of the solid electrolytic capacitor element shown in FIG. [Figure 6] FIG. 6 is a plan view illustrating an example of a solid electrolytic capacitor element according to a second embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view taken along the line XX of the solid electrolytic capacitor element shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along line YY of the solid electrolytic capacitor element shown in FIG. [Figure 9]Fig. 9A is a plan view showing an example of a dielectric layer and an insulating mask layer constituting the solid electrolytic capacitor element shown in Fig. 6. Fig. 9B is a plan view showing an example of a dielectric layer, an insulating mask layer and a solid electrolyte layer constituting the solid electrolytic capacitor element shown in Fig. 6. Fig. 9C is a plan view showing an example of a dielectric layer, an insulating mask layer, a solid electrolyte layer and a carbon layer constituting the solid electrolytic capacitor element shown in Fig. 6. [Figure 10] FIG. 10 is a plan view illustrating an example of a solid electrolytic capacitor element according to a third embodiment of the present invention. [Figure 11] FIG. 11 is a cross-sectional view taken along the line XX of the solid electrolytic capacitor element shown in FIG. [Figure 12] FIG. 12 is a cross-sectional view taken along line YY of the solid electrolytic capacitor element shown in FIG. [Figure 13] Fig. 13A is a plan view showing an example of a dielectric layer and an insulating mask layer constituting the solid electrolytic capacitor element shown in Fig. 10. Fig. 13B is a plan view showing an example of a dielectric layer, an insulating mask layer and a solid electrolyte layer constituting the solid electrolytic capacitor element shown in Fig. 10. Fig. 13C is a plan view showing an example of a dielectric layer, an insulating mask layer, a solid electrolyte layer and a carbon layer constituting the solid electrolytic capacitor element shown in Fig. 10. [Figure 14] FIG. 14 is a schematic diagram showing an example of a step of preparing a valve metal base having an insulating mask layer formed thereon. [Figure 15] FIG. 15 is a schematic diagram showing an example of a process for forming a solid electrolyte layer. [Figure 16] FIG. 16 is a plan view showing a schematic diagram of an example of the element portion after the solid electrolyte layer is formed. [Figure 17] FIG. 17 is a cross-sectional view taken along the line XX of the element portion shown in FIG. [Figure 18] FIG. 18 is a perspective view illustrating an example of the solid electrolytic capacitor of the present invention. [Figure 19] FIG. 19 is a cross-sectional view taken along line ZZ of the solid electrolytic capacitor shown in FIG. [Figure 20]FIG. 20 is a plan view illustrating an example of a solid electrolytic capacitor element according to a comparative example. [Figure 21] FIG. 21 is a cross-sectional view taken along the line XX of the solid electrolytic capacitor element shown in FIG. [Figure 22] Fig. 22A is a plan view showing typically an example of a dielectric layer and an insulating mask layer constituting the solid electrolytic capacitor element shown in Fig. 20. Fig. 22B is a plan view showing typically an example of a dielectric layer, an insulating mask layer and a solid electrolyte layer constituting the solid electrolytic capacitor element shown in Fig. 20. Fig. 22C is a plan view showing typically an example of a dielectric layer, an insulating mask layer, a solid electrolyte layer and a carbon layer constituting the solid electrolytic capacitor element shown in Fig. 20. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The solid electrolytic capacitor element and the solid electrolytic capacitor of the present invention will be described below. However, the present invention is not limited to the following configurations, and can be modified as appropriate within the scope of the present invention. Note that the present invention also includes a combination of two or more of the individual desirable configurations described below.

[0012] [Solid electrolytic capacitor element] The solid electrolytic capacitor element of the present invention comprises a valve action metal base having a dielectric layer on at least one main surface thereof, an insulating mask layer provided on the dielectric layer and separating the valve action metal base into an anode portion and a cathode portion, a solid electrolyte layer provided on the dielectric layer in the cathode portion, a carbon layer provided on the solid electrolyte layer, and a cathode conductor layer provided on the carbon layer.

[0013] In the solid electrolytic capacitor element of the present invention, the solid electrolyte layer is provided so that its tip covers at least a part of the outer surface of the insulating mask layer, the carbon layer is provided so that its tip covers the same position as the tip of the solid electrolyte layer on the outer surface of the insulating mask layer or a position closer to the cathode portion than the tip of the solid electrolyte layer (the side of arrow A in Figures 1, 6 and 10), and the cathode conductor layer is provided so that its tip covers a position closer to the cathode portion than the tip of the carbon layer on the outer surface of the insulating mask layer, thereby making it possible to reduce the equivalent series resistance.

[0014] Furthermore, in the solid electrolytic capacitor element of the present invention, the cathode portion has a cathode conductor layer non-forming region where the cathode conductor layer does not cover a portion of the carbon layer, thereby making it possible to reduce leakage current defects.

[0015] For example, when the solid electrolyte layer is formed by the immersion method (dip method), the solid electrolyte layer sags downward from the vicinity of the insulating mask layer due to its own weight, so that the thickness of the solid electrolyte layer near the insulating mask layer in the cathode part becomes smaller than the thickness of the solid electrolyte layer in the central region of the cathode part. As a result of the study by the present inventors, it was found that if a cathode conductor layer such as a silver layer is formed in a thin part of the solid electrolyte layer, the cathode conductor layer passes through the solid electrolyte layer and contacts the dielectric layer, and there is a risk of short circuit due to conduction by tunnel current or large leakage current. Therefore, the present inventors thought that if a cathode conductor layer is not formed in the thin part of the solid electrolyte layer, the equivalent series resistance can be lowered and leakage current defects can be reduced.

[0016] As described above, in the solid electrolytic capacitor element of the present invention, the solid electrolyte layer is provided so as to cover the cathode portion and to cover at least a portion of the outer surface of the insulating mask layer, the carbon layer is provided so as to cover the cathode portion and to cover at least a portion of the solid electrolyte layer on the outer surface of the insulating mask layer, the cathode conductor layer is provided so as to cover the cathode portion and to cover at least a portion of the carbon layer on the outer surface of the insulating mask layer, and there is a cathode conductor layer-free region in which the cathode conductor layer does not cover any portion of the carbon layer in the cathode portion, thereby making it possible to lower the equivalent series resistance and reduce leakage current defects.

[0017] The following embodiments are merely examples, and it goes without saying that partial replacement or combination of the configurations shown in the different embodiments is possible. From the second embodiment onwards, a description of the matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0018] (First embodiment) In the solid electrolytic capacitor element according to the first embodiment of the present invention, the arcuate tip of the carbon layer is located closer to the cathode portion than the arcuate tip of the solid electrolyte layer, and the arcuate tip of the cathode conductor layer is located closer to the cathode portion than the arcuate tip of the carbon layer. Hereinafter, unless otherwise specified, the arcuate tips of the solid electrolyte layer, carbon layer, and cathode conductor layer will be simply referred to as tips.

[0019] Fig. 1 is a plan view showing a schematic diagram of an example of a solid electrolytic capacitor element according to a first embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line XX of the solid electrolytic capacitor element shown in Fig. 1, and Fig. 3 is a cross-sectional view taken along line YY of the solid electrolytic capacitor element shown in Fig. 1.

[0020] The solid electrolytic capacitor element 1 shown in FIGS. 1, 2 and 3 comprises a valve metal substrate 10 having a dielectric layer 20 on its surface, an insulating mask layer 30 provided on the dielectric layer 20, a solid electrolyte layer 40 provided on the dielectric layer 20, a carbon layer 50 provided on the solid electrolyte layer 40, and a cathode conductor layer 60 provided on the carbon layer 50.

[0021] Fig. 4A is a plan view showing an example of a dielectric layer and an insulating mask layer constituting the solid electrolytic capacitor element shown in Fig. 1. Fig. 4B is a plan view showing an example of a dielectric layer, an insulating mask layer and a solid electrolyte layer constituting the solid electrolytic capacitor element shown in Fig. 1. Fig. 4C is a plan view showing an example of a dielectric layer, an insulating mask layer, a solid electrolyte layer and a carbon layer constituting the solid electrolytic capacitor element shown in Fig. 1.

[0022] 1, 2, 3 and 4A, an insulating mask layer 30 of a predetermined width is provided around the dielectric layer 20. The insulating mask layer 30 is provided on both main surfaces and both side surfaces of the valve metal base 10 so as to follow the short sides of the valve metal base 10. The insulating mask layer 30 separates the valve metal base 10 into an anode portion 31 and a cathode portion 32.

[0023] 1, 2, 3, and 4B, the solid electrolyte layer 40 is provided on the dielectric layer 20 of the cathode portion 32. The solid electrolyte layer 40 is provided such that a tip 40a covers the outer surface of the insulating mask layer 30. The solid electrolyte layer 40 may be provided so as to cover a part of the outer surface of the insulating mask layer 30, or may be provided so as to cover the entire outer surface of the insulating mask layer 30.

[0024] As shown in Figures 1, 2, 3 and 4C, carbon layer 50 is provided such that tip 50a covers a position on the outer surface of insulating mask layer 30 closer to cathode portion 32 than tip 40a of solid electrolyte layer 40.

[0025] As shown in FIGS. 1 and 2, the cathode conductor layer 60 is provided such that a tip 60a covers a position on the outer surface of the insulating mask layer 30 closer to the cathode portion 32 than the tip 50a of the carbon layer 50.

[0026] On the other hand, as shown in FIGS. 1 and 3, the cathode section 32 has cathode conductor layer-free regions A1 and A2 in which the cathode conductor layer 60 does not cover a portion of the carbon layer 50.

[0027] 1, when viewed in the normal direction of the main surface of the valve metal substrate 10, the cathode conductor layer 60 is preferably provided so that the center of the tip 60a is located on the insulating mask layer 30 and both ends of the tip 60a are located on the cathode portion 32. When viewed in the normal direction of the main surface of the valve metal substrate 10, the cathode conductor layer 60 is preferably provided so that it approaches the insulating mask layer 30 from both ends of the tip 60a toward the center of the tip 60a.

[0028] The shape of the valve metal base 10 as viewed from the normal direction of the main surface of the valve metal base 10, i.e., the shape of the valve metal base 10 as viewed in a plan view from the thickness direction, is quadrangular, and preferably rectangular having long and short sides.

[0029] FIG. 5 is an enlarged cross-sectional view of a portion V of the solid electrolytic capacitor element shown in FIG.

[0030] As shown in Fig. 5, a plurality of recesses are provided on the main surface of the valve metal substrate 10. Therefore, the main surface of the valve metal substrate 10 is porous. Since the main surface of the valve metal substrate 10 is porous, the surface area of ​​the valve metal substrate 10 is increased. Note that the valve metal substrate 10 is not limited to a case where both the front and back surfaces are porous, and only one of the front and back surfaces of the valve metal substrate 10 may be porous.

[0031] The valve metal substrate 10 is made of a valve metal, such as an elemental metal such as aluminum, tantalum, niobium, titanium, zirconium, or an alloy containing at least one of these metals. An oxide film can be formed on the surface of the valve metal.

[0032] The valve metal substrate 10 need only be composed of a core and a porous portion provided on at least one of the main surfaces of the core, and may be, for example, a metal foil having an etched surface or a metal foil having a porous sintered powder formed on the surface.

[0033] The dielectric layer 20 is provided on at least one of the main surfaces of the valve metal substrate 10. The dielectric layer 20 is preferably made of an oxide film provided on the surface of the valve metal. For example, the dielectric layer 20 is made of an aluminum oxide. The aluminum oxide is formed by anodizing the surface of the valve metal substrate 10, as described below.

[0034] The insulating mask layer 30 is provided on the dielectric layer 20. As shown in Fig. 5, the insulating mask layer 30 is preferably provided so as to fill a plurality of pores (recesses) of the valve metal base 10. However, it is sufficient that part of the outer surface of the dielectric layer 20 is covered with the insulating mask layer 30, and there may be pores (recesses) of the valve metal base 10 that are not filled with the insulating mask layer 30.

[0035] The insulating mask layer 30 is formed by applying a mask material such as a composition containing an insulating resin. Examples of the insulating resin include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene-perfluoroalkylvinylether copolymer, etc.), a composition of soluble polyimidesiloxane and epoxy resin, polyimide resin, polyamideimide resin, and derivatives or precursors thereof.

[0036] The mask material can be applied by, for example, screen printing, roller transfer, dispenser application, inkjet printing, or the like.

[0037] The solid electrolyte layer 40 is provided on the dielectric layer 20. As shown in Fig. 5, the solid electrolyte layer 40 is preferably provided so as to fill a plurality of pores (recesses) of the valve metal substrate 10. However, it is sufficient that part of the outer surface of the dielectric layer 20 is covered with the solid electrolyte layer 40, and there may be pores (recesses) of the valve metal substrate 10 that are not filled with the solid electrolyte layer 40.

[0038] Materials constituting the solid electrolyte layer 40 include conductive polymers such as polypyrroles, polythiophenes, and polyanilines. Among these, polythiophenes are preferred, and poly(3,4-ethylenedioxythiophene), also known as PEDOT, is particularly preferred. The conductive polymers may contain dopants such as polystyrene sulfonate (PSS).

[0039] The solid electrolyte layer 40 is formed, for example, by a method of forming a polymerized film of a conductive polymer such as poly(3,4-ethylenedioxythiophene) on the surface of the dielectric layer 20 using a liquid containing a polymerizable monomer such as 3,4-ethylenedioxythiophene, or by a method of applying a dispersion liquid of a conductive polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric layer 20 and drying it.

[0040] It is preferable to form an outer layer that covers the entire dielectric layer 20 after forming an inner layer that fills the pores (recesses) of the valve metal substrate 10. The inner layer can be formed by, for example, a dipping method, sponge transfer, screen printing, dispenser application, inkjet printing, etc. Similarly, the outer layer can be formed by, for example, a dipping method, sponge transfer, screen printing, dispenser application, inkjet printing, etc.

[0041] The carbon layer 50 is provided on the solid electrolyte layer 40. The carbon layer 50 is formed, for example, by a method of applying a carbon paste to the surface of the solid electrolyte layer 40 and drying it.

[0042] The carbon paste can be applied by, for example, a dipping method, sponge transfer, screen printing, spray application, dispenser application, inkjet printing, or the like.

[0043] The cathode conductor layer 60 is provided on the carbon layer 50. The cathode conductor layer 60 is formed by, for example, applying a conductive paste containing a metal such as gold, silver, copper, or platinum to the surface of the carbon layer 50 and drying it. The cathode conductor layer 60 is preferably a silver layer.

[0044] The conductive paste can be applied by, for example, a dipping method, sponge transfer, screen printing, spray application, dispenser application, inkjet printing, or the like.

[0045] Second embodiment In the solid electrolytic capacitor element according to the second embodiment of the present invention, the tip of the carbon layer is located at the same position as the tip of the solid electrolyte layer, and the tip of the cathode conductor layer is located closer to the cathode portion than the tip of the carbon layer, but the apex of the arc-shaped tip of the cathode conductor layer is located at the same position as the apex of the arc-shaped tip of the carbon layer.

[0046] Fig. 6 is a plan view showing a schematic diagram of an example of a solid electrolytic capacitor element according to a second embodiment of the present invention. Fig. 7 is a cross-sectional view taken along line XX of the solid electrolytic capacitor element shown in Fig. 6. Fig. 8 is a cross-sectional view taken along line YY of the solid electrolytic capacitor element shown in Fig. 6.

[0047] The solid electrolytic capacitor element 2 shown in Figures 6, 7 and 8 comprises a valve metal substrate 10 having a dielectric layer 20 on its surface, an insulating mask layer 30 provided on the dielectric layer 20, a solid electrolyte layer 40 provided on the dielectric layer 20, a carbon layer 50 provided on the solid electrolyte layer 40, and a cathode conductor layer 60 provided on the carbon layer 50.

[0048] Fig. 9A is a plan view showing an example of a dielectric layer and an insulating mask layer constituting the solid electrolytic capacitor element shown in Fig. 6. Fig. 9B is a plan view showing an example of a dielectric layer, an insulating mask layer and a solid electrolyte layer constituting the solid electrolytic capacitor element shown in Fig. 6. Fig. 9C is a plan view showing an example of a dielectric layer, an insulating mask layer, a solid electrolyte layer and a carbon layer constituting the solid electrolytic capacitor element shown in Fig. 6.

[0049] 6, 7, 8 and 9A, an insulating mask layer 30 of a predetermined width is provided around the dielectric layer 20. The insulating mask layer 30 is provided on both main surfaces and both side surfaces of the valve metal base 10 so as to follow the short sides of the valve metal base 10. The insulating mask layer 30 separates the valve metal base 10 into an anode portion 31 and a cathode portion 32.

[0050] 6, 7, 8, and 9B, the solid electrolyte layer 40 is provided on the dielectric layer 20 of the cathode portion 32. The solid electrolyte layer 40 is provided such that a tip 40a covers the outer surface of the insulating mask layer 30. The solid electrolyte layer 40 may be provided so as to cover a part of the outer surface of the insulating mask layer 30, or may be provided so as to cover the entire outer surface of the insulating mask layer 30.

[0051] As shown in FIGS. 6, 7, 8 and 9C, carbon layer 50 is provided such that tip 50a covers the same position on the outer surface of insulating mask layer 30 as tip 40a of solid electrolyte layer 40.

[0052] 6 and 7, the cathode conductor layer 60 is provided such that the tip 60a covers a position on the outer surface of the insulating mask layer 30 closer to the cathode portion 32 than the tip 50a of the carbon layer 50. However, the top of the tip 60a of the cathode conductor layer 60 is at the same position as the top of the tip 50a of the carbon layer 50.

[0053] On the other hand, as shown in FIGS. 6 and 8, the cathode section 32 has cathode conductor layer-free regions A1 and A2 in which the cathode conductor layer 60 does not cover a portion of the carbon layer 50.

[0054] 6, when viewed in the normal direction of the main surface of the valve metal substrate 10, the cathode conductor layer 60 is preferably provided so that the center of the tip 60a is located on the insulating mask layer 30 and both ends of the tip 60a are located on the cathode portion 32. When viewed in the normal direction of the main surface of the valve metal substrate 10, the cathode conductor layer 60 is preferably provided so that it approaches the insulating mask layer 30 from both ends of the tip 60a toward the center of the tip 60a.

[0055] Third embodiment In the solid electrolytic capacitor element according to the third embodiment of the present invention, the tip of the carbon layer is located closer to the cathode portion than the tip of the solid electrolyte layer, and the tip of the cathode conductor layer is located closer to the cathode portion than the tip of the carbon layer, but the apex of the arc-shaped tip of the cathode conductor layer is located at the same position as the apex of the arc-shaped tip of the carbon layer.

[0056] Fig. 10 is a plan view showing a schematic diagram of an example of a solid electrolytic capacitor element according to a third embodiment of the present invention. Fig. 11 is a cross-sectional view taken along line XX of the solid electrolytic capacitor element shown in Fig. 10. Fig. 12 is a cross-sectional view taken along line YY of the solid electrolytic capacitor element shown in Fig. 10.

[0057] The solid electrolytic capacitor element 3 shown in Figures 10, 11 and 12 comprises a valve metal base 10 having a dielectric layer 20 on its surface, an insulating mask layer 30 provided on the dielectric layer 20, a solid electrolyte layer 40 provided on the dielectric layer 20, a carbon layer 50 provided on the solid electrolyte layer 40, and a cathode conductor layer 60 provided on the carbon layer 50.

[0058] Fig. 13A is a plan view showing an example of a dielectric layer and an insulating mask layer constituting the solid electrolytic capacitor element shown in Fig. 10. Fig. 13B is a plan view showing an example of a dielectric layer, an insulating mask layer and a solid electrolyte layer constituting the solid electrolytic capacitor element shown in Fig. 10. Fig. 13C is a plan view showing an example of a dielectric layer, an insulating mask layer, a solid electrolyte layer and a carbon layer constituting the solid electrolytic capacitor element shown in Fig. 10.

[0059] 10, 11, 12 and 13A, an insulating mask layer 30 of a predetermined width is provided around the dielectric layer 20. The insulating mask layer 30 is provided on both main surfaces and both side surfaces of the valve metal base 10 so as to follow the short sides of the valve metal base 10. The insulating mask layer 30 separates the valve metal base 10 into an anode portion 31 and a cathode portion 32.

[0060] 10 , 11 , 12 and 13B , the solid electrolyte layer 40 is provided on the dielectric layer 20 of the cathode portion 32. The solid electrolyte layer 40 is provided such that a tip 40a covers the outer surface of the insulating mask layer 30. The solid electrolyte layer 40 may be provided so as to cover a part of the outer surface of the insulating mask layer 30, or may be provided so as to cover the entire outer surface of the insulating mask layer 30.

[0061] 10, 11, 12 and 13C, carbon layer 50 is provided such that tip 50a covers a position on the outer surface of insulating mask layer 30 closer to cathode portion 32 than tip 40a of solid electrolyte layer 40.

[0062] 10 and 11 , the cathode conductor layer 60 is provided such that the tip 60a covers a position on the outer surface of the insulating mask layer 30 closer to the cathode portion 32 than the tip 50a of the carbon layer 50. However, the top of the tip 60a of the cathode conductor layer 60 is at the same position as the top of the tip 50a of the carbon layer 50.

[0063] On the other hand, as shown in FIGS. 10 and 12, the cathode section 32 has cathode conductor layer-free regions A1 and A2 in which the cathode conductor layer 60 does not cover a portion of the carbon layer 50.

[0064] 10, when viewed in the normal direction of the main surface of the valve metal substrate 10, the cathode conductor layer 60 is preferably provided so that the center of the tip 60a is located on the insulating mask layer 30 and both ends of the tip 60a are located on the cathode portion 32. When viewed in the normal direction of the main surface of the valve metal substrate 10, the cathode conductor layer 60 is preferably provided so that it approaches the insulating mask layer 30 from both ends of the tip 60a toward the center of the tip 60a.

[0065] As in the first to third embodiments, the arcuate tip of the carbon layer may be located closer to the cathode portion than the arcuate tip of the solid electrolyte layer, and the arcuate tip of the cathode conductor layer may be located closer to the cathode portion than the arcuate tip of the carbon layer, or the arcuate tip of the carbon layer may be located in the same position as the arcuate tip of the solid electrolyte layer, and the arcuate tip of the cathode conductor layer may be located closer to the cathode portion than the arcuate tip of the carbon layer.

[0066] The solid electrolytic capacitor element of the present invention is produced, for example, by the following method: In the following example, a method for simultaneously producing a plurality of solid electrolytic capacitor elements using a large valve metal substrate will be described.

[0067] FIG. 14 is a schematic diagram showing an example of a step of preparing a valve metal base having an insulating mask layer formed thereon.

[0068] As shown in Fig. 14, a valve metal base 10A having a dielectric layer 20 on its surface is prepared. The valve metal base 10A includes a plurality of element portions 11 and a support portion 12. Each element portion 11 has a rectangular shape and protrudes from the support portion 12. An insulating mask layer 30 is formed on the dielectric layer 20 of each element portion 11.

[0069] First, the valve metal substrate 10A having a porous portion on its surface is cut by laser processing, punching processing, or the like, to form a shape including a plurality of element portions 11 and support portions 12.

[0070] Next, an insulating mask layer 30 is formed on both main surfaces and both side surfaces of each element portion 11 so as to extend along the short sides of the element portion 11 .

[0071] Thereafter, the valve metal base 10A is anodized to form an oxide film that will become the dielectric layer 20 on the surface of the valve metal base 10A. At this time, an oxide film is also formed on the side surface of the element portion 11 that has been cut by laser processing, punching, or the like. A chemical foil on which an aluminum oxide has already been formed may be used as the valve metal base 10A. In this case, an oxide film is also formed on the side surface of the cut element portion 11 by anodizing the valve metal base 10A after cutting.

[0072] FIG. 15 is a schematic diagram showing an example of a process for forming a solid electrolyte layer.

[0073] A solid electrolyte layer 40 (see FIG. 4B, etc.) is formed on the dielectric layer 20 of the element portion 11. As shown in FIG. 15, a treatment liquid containing a solid electrolyte is preferably applied to the valve metal base 10A by a dipping method. FIG. 15 shows a state in which a treatment liquid 70 containing a solid electrolyte is supplied to a treatment tank 75.

[0074] As the treatment liquid 70 containing a solid electrolyte, for example, a dispersion liquid of a conductive polymer is used. The dispersion liquid of the conductive polymer can be applied to the outer surface of the dielectric layer 20 and dried to form a conductive polymer film. Alternatively, as the treatment liquid 70 containing a solid electrolyte, a liquid containing a polymerizable monomer, for example, 3,4-ethylenedioxythiophene and an oxidizing agent may be used. The liquid containing the polymerizable monomer can be applied to the outer surface of the dielectric layer 20 to form a conductive polymer film by chemical polymerization. This conductive polymer film becomes the solid electrolyte layer 40.

[0075] 15, the valve metal substrate 10A is immersed in the treatment liquid 70, so that the treatment liquid 70 permeates the porous portion of the valve metal substrate 10A. After a predetermined period of immersion, the valve metal substrate 10A is removed from the treatment liquid 70 and dried at a predetermined temperature for a predetermined period of time. The process of immersion in the treatment liquid 70, removal, and drying is repeated a predetermined number of times to form a solid electrolyte layer 40.

[0076] For example, the first solid electrolyte layer is formed by immersing the valve metal substrate 10A in a first dispersion liquid containing a conductive polymer, removing it from the first dispersion liquid, and drying it. The immersion in the first dispersion liquid, removal from the first dispersion liquid, and drying are repeated several times.

[0077] After the first solid electrolyte layer is formed, the valve metal substrate 10A may be immersed in a solution containing a primer compound, pulled out, and dried to form a primer layer.

[0078] Thereafter, the valve metal substrate 10A is immersed in a second dispersion liquid containing a conductive polymer, and then pulled out and dried to form a second solid electrolyte layer. At this time, the concentration of the conductive polymer in the second dispersion liquid is preferably higher than the concentration of the conductive polymer in the first dispersion liquid.

[0079] The solid electrolyte layer formed by the above method includes a first solid electrolyte layer provided on a dielectric layer and a second solid electrolyte layer provided on the first solid electrolyte layer, and the content of conductive polymer in the second solid electrolyte layer is greater than the content of conductive polymer in the first solid electrolyte layer.

[0080] The valve metal substrate 10A is washed with pure water to remove excess primer compound. After washing, a drying process is performed. In this manner, the solid electrolyte layer 40 is formed in a predetermined region.

[0081] Fig. 16 is a plan view showing a schematic diagram of an example of the element portion after the formation of the solid electrolyte layer, and Fig. 17 is a cross-sectional view taken along the line XX of the element portion shown in Fig. 16.

[0082] As shown in FIGS. 16 and 17, it is preferable that the thickness of solid electrolyte layer 40c provided in the region of cathode portion 32 that contacts insulating mask layer 30 is greater than the thickness of solid electrolyte layer 40b provided in the central region of cathode portion 32.

[0083] As described above, if the thickness of solid electrolyte layer 40c in the cathode portion 32 near insulating mask layer 30 is smaller than the thickness of solid electrolyte layer 40b in the central region of cathode portion 32, there is a risk of short circuiting due to conduction by tunneling current or large leakage current. In contrast, by making the thickness of solid electrolyte layer 40c in the cathode portion 32 near insulating mask layer 30 larger than the thickness of solid electrolyte layer 40b in the central region of cathode portion 32 as shown in Figures 16 and 17, short circuiting is less likely to occur and leakage current defects can be reduced.

[0084] After the solid electrolyte layer 40 is formed, the valve metal substrate 10A is immersed in carbon paste, pulled out, and dried to form a carbon layer 50 (see FIG. 4C, etc.) in a predetermined region.

[0085] After the carbon layer 50 is formed, the valve metal substrate 10A is immersed in a conductive paste such as silver paste, pulled up, and dried to form a cathode conductor layer 60 (see FIG. 1, etc.) in a predetermined region.

[0086] The valve metal substrate 10A is cut to separate the element portion 11.

[0087] Through the above steps, a solid electrolytic capacitor element is obtained.

[0088] [Solid electrolytic capacitor] An example of a solid electrolytic capacitor including the solid electrolytic capacitor element of the present invention will be described below. The solid electrolytic capacitor element of the present invention may be included in a solid electrolytic capacitor having another configuration. For example, a lead frame may be used as an external electrode. The solid electrolytic capacitor of the present invention may also include a solid electrolytic capacitor element other than the solid electrolytic capacitor element of the present invention.

[0089] Fig. 18 is a perspective view showing a schematic diagram of an example of the solid electrolytic capacitor of the present invention, and Fig. 19 is a cross-sectional view taken along line ZZ of the solid electrolytic capacitor shown in Fig. 18.

[0090] 18 and 19, the length direction of solid electrolytic capacitor 100 and exterior housing 110 is indicated by L, the width direction by W, and the height direction by T. Here, the length direction L, the width direction W, and the height direction T are perpendicular to each other.

[0091] 18 and 19, solid electrolytic capacitor 100 has a substantially rectangular parallelepiped outer shape. Solid electrolytic capacitor 100 includes an exterior body 110, a first external electrode 120, a second external electrode 130, and a plurality of solid electrolytic capacitor elements 1. Solid electrolytic capacitor element 1 is an example of the solid electrolytic capacitor element of the present invention.

[0092] Exterior body 110 encapsulates a plurality of solid electrolytic capacitor elements 1. That is, a plurality of solid electrolytic capacitor elements 1 are embedded in exterior body 110. However, exterior body 110 may encapsulate one solid electrolytic capacitor element 1. That is, one solid electrolytic capacitor element 1 may be embedded inside exterior body 110.

[0093] The exterior body 110 has a substantially rectangular parallelepiped outer shape. The exterior body 110 has a first main surface 110a and a second main surface 110b that face each other in a height direction T, a first side surface 110c and a second side surface 110d that face each other in a width direction W, and a first end surface 110e and a second end surface 110f that face each other in a length direction L.

[0094] As described above, exterior body 110 has a substantially rectangular parallelepiped outer shape, but it is preferable that corners and ridges are rounded. A corner is a portion where three faces of exterior body 110 intersect, and a ridge is a portion where two faces of exterior body 110 intersect.

[0095] The exterior body 110 is made of, for example, a sealing resin.

[0096] The sealing resin contains at least a resin, and preferably contains a resin and a filler.

[0097] As the resin, an epoxy resin, a phenol resin, a polyimide resin, a silicone resin, a polyamide resin, a liquid crystal polymer, or the like is preferably used.

[0098] As the filler, silica particles, alumina particles, metal particles, etc. are preferably used.

[0099] As the sealing resin, a material containing a solid epoxy resin, a phenolic resin, and silica particles is preferably used.

[0100] When a solid sealing resin is used, a resin mold such as compression molding or transfer molding is preferably used, and compression molding is more preferably used. When a liquid sealing resin is used, a molding method such as a dispensing method or a printing method is preferably used. Among them, it is preferable to form the exterior body 110 by sealing the periphery of the solid electrolytic capacitor element 1 with the sealing resin by compression molding.

[0101] The exterior body 110 may be composed of a substrate and a sealing resin provided on the substrate. The substrate is, for example, an insulating resin substrate such as a glass epoxy substrate. In this case, the bottom surface of the substrate constitutes the second main surface 110b of the exterior body 110. The thickness of the substrate is, for example, 100 μm.

[0102] The multiple solid electrolytic capacitor elements 1 are stacked in the height direction T. The extending direction of each of the multiple solid electrolytic capacitor elements 1 is approximately parallel to the first main surface 110a and the second main surface 110b of the exterior body 110. The solid electrolytic capacitor elements 1 may be bonded to each other via a conductive adhesive.

[0103] The first external electrode 120 is provided on a first end surface 110e of the exterior body 110. In Fig. 18, the first external electrode 120 is provided from the first end surface 110e of the exterior body 110 to each of the first main surface 110a, the second main surface 110b, the first side surface 110c, and the second side surface 110d. The first external electrode 120 is electrically connected to the valve metal base 10 of the solid electrolytic capacitor element 1 exposed from the exterior body 110. The first external electrode 120 may be directly or indirectly connected to the valve metal base 10 at the first end surface 110e of the exterior body 110.

[0104] The second external electrode 130 is provided on the second end surface 110f of the exterior body 110. In Fig. 18, the second external electrode 130 is provided from the second end surface 110f of the exterior body 110 to each of the first main surface 110a, the second main surface 110b, the first side surface 110c, and the second side surface 110d. The second external electrode 130 is electrically connected to the cathode conductor layer 60 of the solid electrolytic capacitor element 1 exposed from the exterior body 110. The second external electrode 130 may be directly or indirectly connected to the cathode conductor layer 60 at the second end surface 110f of the exterior body 110.

[0105] It is preferable that the first external electrode 120 and the second external electrode 130 are each formed by at least one method selected from the group consisting of a dip coating method, a screen printing method, a transfer method, an inkjet printing method, a dispensing method, a spray coating method, a brush coating method, a drop casting method, an electrostatic painting method, a plating method, and a sputtering method.

[0106] The first external electrode 120 preferably has a resin electrode layer containing a conductive component and a resin component. When the first external electrode 120 contains a resin component, the adhesion between the first external electrode 120 and the sealing resin of the exterior body 110 is improved, thereby improving reliability.

[0107] The second external electrode 130 preferably has a resin electrode layer containing a conductive component and a resin component. When the second external electrode 130 contains a resin component, the adhesion between the second external electrode 130 and the sealing resin of the exterior body 110 is improved, thereby improving reliability.

[0108] The conductive component preferably contains, as a main component, a metal such as silver, copper, nickel, or tin, or an alloy containing at least one of these metals.

[0109] The resin component preferably contains an epoxy resin, a phenolic resin, or the like as a main component.

[0110] The resin electrode layer is formed by, for example, a dip coating method, a screen printing method, a transfer method, an inkjet printing method, a dispensing method, a spray coating method, a brush coating method, a drop casting method, an electrostatic coating method, or the like. Among them, the resin electrode layer is preferably a printed resin electrode layer formed by applying a conductive paste by a screen printing method. When the resin electrode layer is formed by applying a conductive paste by a screen printing method, the first external electrode 120 and the second external electrode 130 are more likely to be flat than when the resin electrode layer is formed by applying a conductive paste by a dip coating method. That is, the thickness of the first external electrode 120 and the second external electrode 130 is more likely to be uniform.

[0111] When the second external electrode 130 has a resin electrode layer, the second external electrode 130, the carbon layer 50, and the cathode conductor layer 60 contain a resin component, which improves the adhesion between the second external electrode 130 and the carbon layer 50 and between the second external electrode 130 and the cathode conductor layer 60, thereby improving reliability.

[0112] At least one of the first external electrode 120 and the second external electrode 130 may have a so-called plating layer formed by a plating method. Examples of the plating layer include a zinc-silver-nickel layer, a silver-nickel layer, a nickel layer, a zinc-nickel-gold layer, a nickel-gold layer, a zinc-nickel-copper layer, and a nickel-copper layer. On these plating layers, for example, a copper plating layer, a nickel plating layer, and a tin plating layer are preferably provided in this order (or with the exception of some plating layers).

[0113] At least one of the first external electrode 120 and the second external electrode 130 may have both a resin electrode layer and a plating layer. For example, the first external electrode 120 may have a resin electrode layer connected to the valve metal base 10 and an outer plating layer provided on the surface of the resin electrode layer. The first external electrode 120 may also have an inner plating layer connected to the valve metal base 10, a resin electrode layer provided so as to cover the inner plating layer, and an outer plating layer provided on the surface of the resin electrode layer. EXAMPLES

[0114] EXAMPLES Hereinafter, examples will be given that more specifically disclose the solid electrolytic capacitor element of the present invention, but the present invention is not limited to these examples.

[0115] [Fabrication of solid electrolytic capacitor elements] (Example) A total of ten solid electrolytic capacitor elements 1 shown in Figures 1, 2 and 3 were produced as Examples 1 to 10. The production method is described below.

[0116] 14, a rectangular valve metal base 10A having a plurality of element portions 11 is formed by laser processing or punching. The valve metal base 10A has a porous portion that has been etched with hydrochloric acid or the like.

[0117] (2) An insulating mask layer 30 is formed on both main surfaces and both side surfaces of the element portion 11 along the short sides of the element portion 11. The insulating mask layer 30 is formed so that the dimensions of the capacitive portion in one element portion 11 are predetermined dimensions, between a dimension in the length direction L of 4.5 mm to 7.0 mm and a dimension in the width direction W of 3.0 mm to 4.0 mm. The dimensions of the insulating mask layer 30 are formed so that the length of the capacitive portion along the length direction L is 0.5 mm to 2 mm.

[0118] (3) The valve metal substrate 10 is anodized to form an oxide film that will become the dielectric layer 20 on the element portion 11. An oxide film is also formed on the side surface of the element portion 11 that has been processed by laser machining or punching. The valve metal substrate 10A is anodized in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or a sodium salt or ammonium salt thereof, to form an oxide film.

[0119] (4) The valve metal substrate 10A is immersed in a dispersion liquid containing a conductive polymer that constitutes the first solid electrolyte layer, thereby impregnating the dispersion liquid and forming the first solid electrolyte layer in the region shown in FIG. 4B. After immersion, a drying process is performed. The process of (4) is repeated multiple times. In the immersion conditions, the pull-down speed (immersion speed) is optimized to improve the impregnation of the dispersion liquid into the porous portion, which results in improved capacitance, which will be described later.

[0120] (5) The valve metal substrate 10A is immersed in a solution containing a primer compound (see Japanese Patent No. 6449914, a bifunctional or polyfunctional monomer compound containing at least one amine group and at least one carboxylic acid group or sulfonic acid group) to form a primer layer in the region shown in Fig. 4B. After immersion, a drying treatment is performed.

[0121] During the drying process, if the rectangular valve metal substrate 10A is dried in a state where it is inverted 180 degrees during drying, the solution containing the primer compound is likely to accumulate near the insulating mask layer 30, resulting in a large amount of primer compound adhering after drying.

[0122] In addition, by optimizing the withdrawal speed (immersion speed) under the conditions of immersion in a solution containing a primer compound, specifically by making the withdrawal speed slower than the speed at which the solution containing the primer compound permeates the valve action metal substrate 10A having a porous portion, the impregnation of the porous portion is improved, and the amount of primer compound adhered after drying is increased.

[0123] (6) The valve metal substrate 10A is immersed in a dispersion liquid containing a conductive polymer that constitutes the second solid electrolyte layer, thereby impregnating the substrate with the dispersion liquid and forming the second solid electrolyte layer in the region shown in Fig. 4B. After immersion, a drying process is performed.

[0124] During the drying process, if the rectangular valve metal substrate 10A is inverted 180 degrees during drying, the solution containing the solid electrolyte tends to accumulate near the insulating mask layer 30, and the cross-linking reaction with the primer compound causes the thickness of the second solid electrolyte layer after drying to increase. If the substrate is inverted 180 degrees during the drying process in (5), the cross-linking reaction with the primer compound is further promoted, and the thickness of the second solid electrolyte layer after drying increases, but it is also effective to simply optimize the immersion conditions. As a result, the equivalent series resistance (ESR) described below is improved.

[0125] The second solid electrolyte layer is formed by impregnation with a dispersion liquid having a higher concentration of conductive polymer than the first solid electrolyte layer.

[0126] Due to the above (5) or (6), the thickness of solid electrolyte layer 40 in cathode portion 32 near insulating mask layer 30 is greater than the thickness of the central region of cathode portion 32.

[0127] (7) The rectangular valve metal substrate 10A is washed with pure water to remove excess primer compound, and then dried.

[0128] (8) The valve metal substrate 10A is immersed in carbon paste to form a carbon layer 50 in the region shown in Fig. 4C. After immersion, a drying process is performed.

[0129] (9) The valve metal substrate 10A is immersed in the silver paste to form the cathode conductor layer 60 in the region shown in Fig. 1. After immersion, a drying process is performed.

[0130] (Comparative Example) A total of ten solid electrolytic capacitor elements 1A shown in Figures 20 and 21 were fabricated as Comparative Examples 1 to 10. The fabrication method was the same as that of the Examples.

[0131] Fig. 20 is a plan view showing a schematic diagram of an example of a solid electrolytic capacitor element according to a comparative example, and Fig. 21 is a cross-sectional view taken along line XX of the solid electrolytic capacitor element shown in Fig. 20.

[0132] The solid electrolytic capacitor element 1A shown in Figures 20 and 21 comprises a valve action metal substrate 10 having a dielectric layer 20 on its surface, an insulating mask layer 30 provided on the dielectric layer 20, a solid electrolyte layer 40 provided on the dielectric layer 20, a carbon layer 50 provided on the solid electrolyte layer 40, and a cathode conductor layer 60 provided on the carbon layer 50.

[0133] Fig. 22A is a plan view showing typically an example of a dielectric layer and an insulating mask layer constituting the solid electrolytic capacitor element shown in Fig. 20. Fig. 22B is a plan view showing typically an example of a dielectric layer, an insulating mask layer and a solid electrolyte layer constituting the solid electrolytic capacitor element shown in Fig. 20. Fig. 22C is a plan view showing typically an example of a dielectric layer, an insulating mask layer, a solid electrolyte layer and a carbon layer constituting the solid electrolytic capacitor element shown in Fig. 20.

[0134] 20, 21 and 22A, an insulating mask layer 30 of a predetermined width is provided around the dielectric layer 20. The insulating mask layer 30 is provided on both main surfaces and both side surfaces of the valve metal base 10 so as to follow the short sides of the valve metal base 10. The insulating mask layer 30 separates the valve metal base 10 into an anode portion 31 and a cathode portion 32.

[0135] 20, 21, and 22B, the solid electrolyte layer 40 is provided on the dielectric layer 20 of the cathode portion 32. The solid electrolyte layer 40 is provided so that its tip covers the outer surface of the insulating mask layer 30. The solid electrolyte layer 40 may be provided so as to cover a part of the outer surface of the insulating mask layer 30, or may be provided so as to cover the entire outer surface of the insulating mask layer 30.

[0136] As shown in Figures 20, 21 and 22C, the carbon layer 50 is provided so that the tip 50a covers the outer surface of the insulating mask layer 30, and the tip 50a covers the same position on the outer surface of the insulating mask layer 30 as the tip 40a of the solid electrolyte layer 40.

[0137] As shown in FIGS. 20 and 21, the cathode conductor layer 60 is provided such that a tip 60 a covers the same position on the outer surface of the insulating mask layer 30 as the tip 50 a of the carbon layer 50 .

[0138] As shown in FIGS. 20 and 21, the cathode section 32 does not have a cathode conductor layer-free region where the cathode conductor layer 60 does not cover a portion of the carbon layer 50 .

[0139] [Evaluation of solid electrolytic capacitor elements] For the solid electrolytic capacitor elements of Examples 1 to 10 and Comparative Examples 1 to 10, the capacitance at 120 Hz, the equivalent series resistance (ESR) at 100 kHz, and the leakage current (LC) were measured as initial characteristics. The leakage current was measured 2 minutes after applying a rated voltage of 16 V. The average value (Avg) and standard deviation (σ) were calculated for the capacitance and ESR. For LC, values ​​less than 5 μA were judged as ○ (good), values ​​between 5 μA and 200 μA were judged as △ (passable), and values ​​of 200 μA or more that caused a short circuit were judged as × (unacceptable). The results are shown in Table 1.

[0140] [Table 1]

[0141] It can be seen from Table 1 that the solid electrolytic capacitor elements according to the examples have lower equivalent series resistance and fewer leakage current defects than the solid electrolytic capacitor elements according to the comparative examples. [Explanation of symbols]

[0142] 1, 1A, 2, 3 Solid electrolytic capacitor element 10, 10A Valve metal substrate 11. Element section 12 Support part 20 Dielectric layer 30 Insulating Mask Layer 31 Anode 32 Cathode 40 Solid electrolyte layer 40a Tip of solid electrolyte layer 40b A solid electrolyte layer provided in the central region of the cathode part 40c A solid electrolyte layer provided in the region in contact with the insulating mask layer in the cathode portion 50 Carbon Layer 50a carbon layer tip 60 Cathode conductor layer 60a Tip of cathode conductor layer 70 Processing fluid 75 Treatment tank 100 Solid electrolytic capacitor 110 Exterior body 110a 1st main surface 110b 2nd principal surface 110c 1st side 110d 2nd side 110e 1st end face 110f 2nd end face 120 1st external electrode 130 2nd external electrode A1, A2 Cathode conductor layer non-formation area

Claims

1. a valve metal substrate having a dielectric layer on at least one of its principal surfaces; an insulating mask layer disposed on the dielectric layer and separating the valve metal substrate into an anode portion and a cathode portion; a solid electrolyte layer provided on the dielectric layer of the cathode portion; a carbon layer provided on the solid electrolyte layer; a cathode conductor layer provided on the carbon layer, the solid electrolyte layer is provided such that a tip thereof covers at least a portion of an outer surface of the insulating mask layer; a thickness of the solid electrolyte layer provided in a region of the cathode portion that contacts the insulating mask layer is smaller than a thickness of the solid electrolyte layer provided in a central region of the cathode portion, the carbon layer is provided such that a tip thereof covers the same position as the tip of the solid electrolyte layer on the outer surface of the insulating mask layer or a position closer to the cathode portion than the tip of the solid electrolyte layer, the cathode conductor layer is provided such that a tip end covers a position on the outer surface of the insulating mask layer that is closer to the cathode portion than the tip end of the carbon layer, The cathode portion has a cathode conductor layer non-formed region where the cathode conductor layer does not cover a portion of the carbon layer.

2. 2. The solid electrolytic capacitor element according to claim 1, wherein, when viewed from a normal direction of a main surface of the valve metal base, the cathode conductor layer is arranged so that a center portion of the tip is located on the insulating mask layer and both ends of the tip are located on the cathode portion.

3. 3. The solid electrolytic capacitor element according to claim 1, wherein when viewed from a normal direction of a main surface of the valve metal base, the cathode conductor layer is provided so as to approach the insulating mask layer from both ends of the tip toward the center of the tip.

4. the solid electrolyte layer includes a first solid electrolyte layer provided on the dielectric layer and a second solid electrolyte layer provided on the first solid electrolyte layer, 3 . The solid electrolytic capacitor element according to claim 1 , wherein the second solid electrolyte layer contains a conductive polymer that is greater in content than the first solid electrolyte layer.

5. 3. The solid electrolytic capacitor element according to claim 1, wherein the cathode conductor layer is a silver layer.

6. The solid electrolytic capacitor element according to claim 1 or 2, an exterior body that encapsulates the solid electrolytic capacitor element; a first external electrode electrically connected to the valve metal base of the solid electrolytic capacitor element exposed from the exterior body; a second external electrode electrically connected to the cathode conductor layer of the solid electrolytic capacitor element exposed from the exterior housing.

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