Electrolytic capacitor element

Abstract

An electrolytic capacitor element 1 comprises: a positive electrode 10 that is formed from a valve-action metal substrate 11, and has a leading end surface 10a and a base end surface 10b; a dielectric layer 20 provided on at least one of main surfaces 10c, 10d of the positive electrode 10, excluding at least the base end surface 10b; a mask layer 30 formed from an insulating material and provided on the dielectric layer 20 along the base end surface 10b; and a negative electrode 40 provided on the dielectric layer 20 farther on the leading end surface 10a side as compared to the mask layer 30. The negative electrode 40 has a solid electrolyte layer 50 provided on the dielectric layer 20, and an electroconductive layer 60 provided on the solid electrolyte layer 50. The solid electrolyte layer 50 includes a first layer 51 containing a first electroconductive polymer and provided on the dielectric layer 20, a second layer 52 containing a second electroconductive polymer and a binder component, and a third layer 53 containing a third electroconductive polymer and provided on at least the first layer 51. The second layer 52 is disposed partially within the plane of the solid electrolyte layer 50, and the first layer 51 and the third layer 53 are disposed at least in a region where the second layer 52 is not disposed within the plane of the solid electrolyte 50.

Description

[Technical Field]

[0001] The present invention relates to an electrolytic capacitor element. [Background technology]

[0002] Patent Document 1 discloses a solid electrolytic capacitor with low equivalent series resistance (ESR) and low leakage current, which includes an anode body made of a valve action metal, a dielectric oxide film formed on the surface of the anode body, a solid electrolyte layer on the dielectric oxide film, and a cathode current collector layer on the solid electrolyte layer, wherein the solid electrolyte layer comprises: a first solid electrolyte layer formed on the dielectric oxide film from a solution or dispersion containing a conductive polymer selected from the group consisting of polyaniline, polypyrrole, and derivatives thereof; a second solid electrolyte layer formed on the first solid electrolyte layer from a solution or dispersion containing a conductive polymer selected from the group consisting of polythiophene and derivatives thereof; and a third solid electrolyte layer formed on the second solid electrolyte layer from a solution or dispersion containing a conductive polymer selected from the group consisting of polythiophene and derivatives thereof and having a different composition from the solution or dispersion used to form the second solid electrolyte layer.

[0003] Patent Document 2 discloses that in a solid electrolytic capacitor having an anode body made of a valve action metal foil with a porous surface enlarged to reduce the defect rate due to leakage current, an insulating resin layer is formed between the second solid electrolyte layer and a graphite layer in the capacitor element so as to extend from the side surface of the second solid electrolyte layer and cover at least a part of the outer edge of the flat surface of the second solid electrolyte layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-253878 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-134389 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the first solid electrolyte layer uses a conductive polymer based on polyaniline or polypyrrole, and the second and third solid electrolyte layers use a conductive polymer based on polythiophene, but there is room for improvement in that the first and second solid electrolyte layers are made of different materials, and poor adhesion between these layers increases the interfacial resistance, resulting in a high equivalent series resistance (ESR). Furthermore, it is also stated that each layer may use a dispersion containing an insulating binder (polyvinyl alcohol, see paragraph

[0030] ), which reduces the conductivity of the conductive polymer film (bulk), resulting in a high ESR, leaving room for improvement.

[0006] In Patent Document 2, the side surfaces (corners) of the element, which are easily damaged by molding stress during molding, are partially covered with an insulator, which deteriorates the electrical response between the solid electrolyte layer and the graphite layer and silver paste layer (lengthens the path), resulting in a high ESR, leaving room for improvement. Furthermore, when forming the graphite layer, different materials are exposed, so the wettability of the surface is not consistent, making it impossible to form a uniform coating, resulting in variations in ESR characteristics.

[0007] The present invention has been made to solve the above problems, and has an object to provide an electrolytic capacitor element that can suppress leakage current while suppressing an increase in equivalent series resistance. [Means for solving the problem]

[0008] In a first aspect, the electrolytic capacitor element of the present invention comprises: an anode made of a valve action metal substrate and having a tip end surface and a base end surface; a dielectric layer provided on at least one main surface of the anode excluding at least the base end surface; a mask layer made of an insulating material and provided on the dielectric layer along the base end surface; and a cathode provided on the dielectric layer on the tip end surface side of the mask layer, the cathode having a solid electrolyte layer provided on the dielectric layer and a conductive layer provided on the solid electrolyte layer, the solid electrolyte layer including: a first layer provided on the dielectric layer and containing a first conductive polymer; a second layer provided on the dielectric layer and containing a second conductive polymer and a binder component; and a third layer provided at least on the first layer and containing a third conductive polymer, the second layer being partially disposed within the plane of the solid electrolyte layer, and the first layer and the third layer being disposed at least in regions of the plane of the solid electrolyte layer where the second layer is not disposed.

[0009] In a second aspect, the electrolytic capacitor element of the present invention comprises: an anode made of a valve metal substrate and having a tip end surface and a base end surface; a dielectric layer provided on at least one main surface of the anode excluding at least the base end surface; a mask layer made of an insulating material provided on the dielectric layer along the base end surface; and a cathode provided on the dielectric layer on the tip end surface side of the mask layer, wherein the cathode comprises a solid electrolyte layer provided on the dielectric layer and a conductive layer provided on the solid electrolyte layer. the solid electrolyte layer is provided on the dielectric layer and includes a first layer including a first conductive polymer, a second layer including a second conductive polymer, and a third layer provided at least on the first layer and including a third conductive polymer, the second layer being partially disposed within a plane of the solid electrolyte layer, the first layer and the third layer being disposed at least in an area within the plane of the solid electrolyte layer where the second layer is not disposed, and the second layer is a denser film than the first layer and the third layer. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an electrolytic capacitor element that can suppress leakage current while suppressing an increase in equivalent series resistance. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view schematically showing an example of an electrolytic capacitor element according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the electrolytic capacitor element shown in FIG. 1 taken along line XX. [Figure 3] FIG. 3 is a perspective view of the electrolytic capacitor element shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA of the electrolytic capacitor element shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line BB of the electrolytic capacitor element shown in FIG. [Figure 6] FIG. 6 is a perspective view schematically illustrating an example of an electrolytic capacitor element according to another embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view taken along line CC of the electrolytic capacitor element shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along line DD of the electrolytic capacitor element shown in FIG. [Figure 9] FIG. 9 is a perspective view schematically showing an example of an electrolytic capacitor element according to still another embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view taken along line EE of the electrolytic capacitor element shown in FIG. [Figure 11] FIG. 11 is a cross-sectional view taken along line FF of the electrolytic capacitor element shown in FIG. [Figure 12] FIG. 12 is a perspective view schematically illustrating an example of an electrolytic capacitor element according to still another embodiment of the present invention. [Figure 13] FIG. 13 is a cross-sectional view taken along line GG of the electrolytic capacitor element shown in FIG. [Figure 14] FIG. 14 is a cross-sectional view taken along line HH of the electrolytic capacitor element shown in FIG. [Figure 15] FIG. 15 is an enlarged cross-sectional view of the mask layer portion of the electrolytic capacitor element shown in FIG. [Figure 16] FIG. 16 is a schematic diagram showing an example of a step of preparing a valve metal substrate on which a mask layer is formed. [Figure 17] FIG. 17 is a schematic view showing an example of a process for forming the first and third layers of the solid electrolyte layer. [Figure 18] FIG. 18 is a schematic view showing an example of a step of forming the second layer of the solid electrolyte layer. [Figure 19] FIG. 19 is a perspective view that schematically illustrates an example of an electrolytic capacitor that includes an electrolytic capacitor element according to an embodiment of the present invention. [Figure 20] FIG. 20 is a cross-sectional view taken along line ZZ of the electrolytic capacitor shown in FIG. [Figure 21] FIG. 21 shows an SEM photograph of a cross section of the electrolytic capacitor of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] The electrolytic capacitor element of the present invention will now be described. However, the present invention is not limited to the following configurations, and can be appropriately modified and applied 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.

[0013] Furthermore, the embodiments described below are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Repetition of descriptions of matters common to multiple embodiments will be omitted, and only differences will be described.

[0014] [Electrolytic capacitor element] Fig. 1 is a plan view schematically illustrating an example of an electrolytic capacitor element according to an embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line XX of the electrolytic capacitor element shown in Fig. 1. Note that in Fig. 1, a solid electrolyte layer 50 covered with a conductive layer 60 is indicated by a dashed line. Furthermore, in Figs. 1 and 2, the solid electrolyte layer 50 is shown without distinguishing between the first layer 51, the second layer 52, and the third layer 53.

[0015] The electrolytic capacitor element 1 shown in FIGS. 1 and 2 is a solid electrolytic capacitor element, and includes: an anode 10 made of a valve metal substrate 11 and having a tip end surface 10a and a base end surface 10b; a dielectric layer 20 provided on the surface of the anode 10 except for the base end surface 10b; a mask layer 30 made of an insulating material provided on the dielectric layer 20 along the base end surface 10b; and a cathode 40 provided on the dielectric layer 20 closer to the tip end surface 10a than the mask layer 30. The cathode 40 has a solid electrolyte layer 50 provided on the dielectric layer 20 and a conductive layer 60 provided on the solid electrolyte layer 50.

[0016] Fig. 3 is a perspective view of the electrolytic capacitor element shown in Fig. 1. Fig. 4 is a cross-sectional view of the electrolytic capacitor element shown in Fig. 3 taken along line AA. Fig. 5 is a cross-sectional view of the electrolytic capacitor element shown in Fig. 3 taken along line BB. Figs. 3, 4, and 5 show the state before the conductive layer 60 of the cathode 40 is formed. Fig. 3 does not show the dielectric layer 20, and also shows a see-through state of the members inside the third layer 53 of the solid electrolyte layer 50.

[0017] As shown in Figures 3, 4, and 5, the solid electrolyte layer 50 is provided on the dielectric layer 20 and includes a first layer 51 containing a first conductive polymer, a second layer 52 containing a second conductive polymer and a binder component, and a third layer 53 provided at least on the first layer 51 and containing a third conductive polymer, the second layer 52 being partially disposed within the plane of the solid electrolyte layer 50, and the first layer 51 and the third layer 53 being disposed at least in regions within the plane of the solid electrolyte layer 50 where the second layer 52 is not disposed. This makes it possible to suppress leakage current while suppressing an increase in the equivalent series resistance of the electrolytic capacitor element 1. The reason (action) for obtaining this effect is thought to be as follows. (1) While each layer contains a conductive polymer, the second layer 52 contains a binder component. Therefore, the first layer 51 and the third layer 53 can be made into a highly conductive film that does not contain a binder component or has a small amount of binder component, and the second layer can be made into a dense and / or deformation-compliant film. (2) Because the second layer 52 is partially disposed within the plane of the solid electrolyte layer 50, a dense and / or conformable conductive polymer film can be locally disposed in locations where leakage current is likely to occur, such as the corners and tip of the anode 10 where stress is likely to concentrate. This prevents thin film portions from being formed in locations where the solid electrolyte layer 50 is difficult to adhere to, such as the corners and ridges of the tip surface 10a of the anode 10 (valve metal substrate) or the portions along the mask layer 30. As a result, leakage current can be reduced. (3) The first layer 51 and the third layer 53, which are more conductive than the second layer 52 and thus can suppress an increase in equivalent series resistance, are disposed at least in the area of ​​the surface of the solid electrolyte layer 50 where the second layer 52 is not disposed, thereby preventing an increase in the equivalent series resistance of the entire electrolytic capacitor element 1. From the above, it is believed that the leakage current can be reduced while suppressing an increase in the equivalent series resistance of the entire electrolytic capacitor element 1.

[0018] The term "dense and / or conformable film" refers to a film that has the strength and / or conformability to prevent the film from decomposing and becoming locally thin when heated and the anode deforms during processes such as sealing, stacking, and reflow. Heating can cause differences in expansion between the second layer 52 and the first and third layers 51 and 53, potentially generating stress. The presence of such a film as the second layer 52 is believed to deform the second layer 52 and relieve the stress. The conformability of the film, in particular, can improve the flexibility of the film and thereby enhance the characteristics of the electrolytic capacitor element 1.

[0019] From the viewpoint of preventing leakage current alone, it may be possible to arrange the second layer 52 over the entire surface of the solid electrolyte layer 50. However, in this case, the conductivity of the entire solid electrolyte layer 50 may decrease, possibly resulting in an increase in the equivalent series resistance of the electrolytic capacitor element 1.

[0020] In this specification, the term "conductive polymer" includes a main chain and a dopant.

[0021] The first layer 51 and the third layer 53 each preferably contain less binder components, and more preferably contain no binder components, compared to the second layer 52. This makes it possible to more effectively suppress an increase in equivalent series resistance.

[0022] Here, "not containing a binder component" includes the case where the binder component is substantially not contained.

[0023] The second layer 52 is preferably a denser film than the first layer 51 and the third layer 53. This makes it possible to more effectively suppress leakage current.

[0024] Thus, in the electrolytic capacitor element 1 of this embodiment, the second layer 52 contains a second conductive polymer (however, the presence or absence of a binder component is not important), and may be a denser film than the first layer 51 and the third layer 53. This also makes it possible to suppress leakage current while suppressing an increase in the equivalent series resistance of the electrolytic capacitor element 1. (A) While each layer contains a conductive polymer, the second layer 52 is a denser film than the first layer 51 and the third layer 53, so that the first layer 51 and the third layer 53 can be made into highly conductive films and the second layer can be made into a dense film. (B) Since the second layer 52 is partially disposed within the plane of the solid electrolyte layer 50, a dense conductive polymer film can be locally disposed in locations where leakage current is likely to occur, such as the corners and tip of the anode 10 where stress is likely to concentrate. This prevents thin film portions from being formed in locations where the solid electrolyte layer 50 is difficult to adhere to during formation, such as the corners and ridges of the tip surface 10a of the anode 10 (valve metal substrate) or the portions along the mask layer 30. As a result, leakage current can be reduced. (C) The first layer 51 and the third layer 53, which are more conductive than the second layer 52, i.e., which can suppress an increase in equivalent series resistance, are disposed at least in the area of ​​the surface of the solid electrolyte layer 50 where the second layer 52 is not disposed, and therefore an increase in the equivalent series resistance of the entire electrolytic capacitor element 1 is prevented. From the above, it is believed that the leakage current can be reduced while suppressing an increase in the equivalent series resistance of the entire electrolytic capacitor element 1.

[0025] Whether or not "the second layer is a denser film than the first and third layers" can be determined from a cross-sectional photograph including the first, second, and third layers. In the cross-sectional photograph, the second layer is observed to have a smooth (film-like) surface. On the other hand, the first and third layers are observed to have rougher surfaces than the second layer.

[0026] Furthermore, the method for making the second layer 52 a denser film than the first layer 51 and the third layer 53 is not particularly limited to the method of incorporating the binder component described above, and may be, for example, the following method. (I) A polymerization reaction of the second conductive polymer is carried out on the dielectric layer 20 at a low temperature. (II) The polymerization reaction of the second conductive polymer is carried out slowly on the dielectric layer 20 using a polymerization retarder (such as a silane coupling agent). Either method makes it easier to generate fine polymers, and therefore the second layer 52, which is a mass of these polymers, can be made into a dense layer.

[0027] 3, 4, and 5, the anode 10 has six surfaces: a tip surface 10a, a base surface 10b, a pair of main surfaces 10c and 10d, and a pair of side surfaces 10e and 10f, and also has corners where three of these six surfaces intersect and ridges where two of these six surfaces intersect, and the second layer 52 covers each corner 10g of the tip surface 10a. Generally, leakage current is likely to occur at the corners of an anode, so this can more effectively suppress leakage current.

[0028] Fig. 6 is a perspective view schematically illustrating one example of an electrolytic capacitor element according to another embodiment of the present invention. Fig. 7 is a cross-sectional view taken along line CC of the electrolytic capacitor element shown in Fig. 6. Fig. 8 is a cross-sectional view taken along line DD of the electrolytic capacitor element shown in Fig. 6. Note that Figs. 6, 7, and 8 show the state before the conductive layer 60 of the cathode 40 is formed. Furthermore, Fig. 6 omits the illustration of the dielectric layer 20, and also shows a see-through state of the members inside the third layer 53 of the solid electrolyte layer 50.

[0029] As shown in Figures 6, 7, and 8, the second layer 52 may further cover the tip surface 10a and each ridge portion 10h formed by the tip surface 10a. Since leakage current is generally likely to occur at the ridge portion of the anode, this configuration can more effectively suppress leakage current. Furthermore, the second layer 52 is easier to form in the case shown in Figure 6 than in the case shown in Figure 3.

[0030] In this specification, a corner is a portion where three faces intersect, and a ridge is a portion where two faces intersect. Also, a corner formed by a certain face means a corner where three faces including that face intersect, and a ridge by a certain face means a ridge where two faces including that face intersect.

[0031] Fig. 9 is a perspective view schematically illustrating an example of an electrolytic capacitor element according to yet another embodiment of the present invention. Fig. 10 is a cross-sectional view taken along line EE of the electrolytic capacitor element shown in Fig. 9. Fig. 11 is a cross-sectional view taken along line FF of the electrolytic capacitor element shown in Fig. 9. Note that Figs. 9, 10, and 11 show the state before the conductive layer 60 of the cathode 40 is formed. Furthermore, Fig. 9 omits the illustration of the dielectric layer 20 and shows a see-through state of the members inside the third layer 53 of the solid electrolyte layer 50.

[0032] 9, 10, and 11, the second layer 52 may further cover the side surfaces 10e, 10f and the ridges 10j formed by the side surfaces 10e, 10f, thereby making it possible to particularly effectively suppress leakage current.

[0033] Fig. 12 is a perspective view schematically illustrating an example of an electrolytic capacitor element according to yet another embodiment of the present invention. Fig. 13 is a cross-sectional view taken along line GG of the electrolytic capacitor element shown in Fig. 12. Fig. 14 is a cross-sectional view taken along line HH of the electrolytic capacitor element shown in Fig. 12. Note that Figs. 12, 13, and 14 show the state before the conductive layer 60 of the cathode 40 is formed. Furthermore, Fig. 12 omits the illustration of the dielectric layer 20 and shows a see-through state of the members inside the third layer 53 of the solid electrolyte layer 50.

[0034] 12, 13, and 14, the second layer 52 may be disposed along the mask layer 30. The solid electrolyte layer may be thin in areas along the mask layer, which may result in leakage current. However, by disposing the second layer 52 along the mask layer 30, leakage current in areas along the mask layer 30 can be effectively suppressed.

[0035] Furthermore, although not shown, a second layer may be formed that has a combination of the structure shown in Fig. 3, 6 or 9 and the structure shown in Fig. 12. That is, for example, by combining the structures shown in Fig. 6 and 12, the second layer 52 may cover each corner 10g formed by the tip surface 10a, the tip surface 10a, and each ridge portion 10h formed by the tip surface 10a, and may be arranged along the mask layer 30.

[0036] Each component of the electrolytic capacitor element 1 will be described in detail below.

[0037] The anode 10 is a thin film (foil) made of a valve metal substrate 11 and has a quadrangular shape in plan view, preferably a rectangular shape (strip shape) having a pair of long sides and a pair of short sides in plan view. The tip end surface 10a and the base end surface 10b are end surfaces located on a pair of sides (preferably a pair of short sides) of the anode 10, and the base end surface 10b is an exposed end surface not covered with the dielectric layer 20, exposed at one end surface of the electrolytic capacitor and connected to an external electrode (described later). The anode 10 has the tip end surface 10a, the base end surface 10b, main surfaces 10c and 10d, and side surfaces 10e and 10f.

[0038] In this specification, the term "plan view" means a view from the normal direction of the main surface of the anode (valve metal substrate).

[0039] FIG. 15 is an enlarged cross-sectional view of the mask layer portion of the electrolytic capacitor element shown in FIG.

[0040] As shown in Fig. 15, a plurality of recesses are provided on each main surface of the valve metal substrate 11 (anode 10). Therefore, each main surface of the valve metal substrate 11 is porous. This increases the surface area of ​​the valve metal substrate 11. Note that both main surfaces of the valve metal substrate 11 are not limited to being porous, and only one of the main surfaces of the valve metal substrate 11 may be porous.

[0041] The valve metal substrate 11 is made of a valve metal such as an elemental metal such as aluminum, tantalum, niobium, titanium, or zirconium, or an alloy containing these metals. An oxide film can be formed on the surface of the valve metal.

[0042] The valve metal substrate 11 may be formed of a core and a porous portion provided on at least one of the main surfaces of the core, and may be formed of a metal foil with an etched surface, a metal foil with a porous sintered powder body formed on the surface, or the like.

[0043] Here, the dielectric layer 20 is provided on the surface of the anode 10 except for the base end surface 10b. That is, the dielectric layer 20 is provided on the tip end surface 10a, the main surfaces 10c and 10d, and the side surfaces 10e and 10f of the anode 10, but is not provided on the base end surface 10b of the anode 10. However, it is sufficient that the dielectric layer 20 is provided on at least one of the main surfaces 10c and 10d of the anode 10, excluding at least the base end surface 10b.

[0044] The dielectric layer 20 is preferably made of an oxide film provided on the surface of the valve metal substrate 11. For example, the dielectric layer 20 is made of aluminum oxide. The aluminum oxide is formed by anodizing the surface of the valve metal substrate 11, as will be described later.

[0045] The mask layer 30 is a linear (stripe-like) insulating member provided on the dielectric layer 20 along the base end surface 10b of the anode 10, preferably along the short side of the anode 10. The mask layer 30 separates the anode 10 from the cathode 40, ensuring insulation between them. The mask layer 30 partitions the anode 10 into a region on the base end surface 10b side and a region on the tip end surface 10a side. Here, the mask layer 30 is disposed at a predetermined distance from the base end surface 10b, but it may be disposed up to the edge of the base end surface 10b. The mask layer 30 is provided on the principal surfaces 10c and 10d and the side surfaces 10e and 10f of the anode 10 via the dielectric layer 20. However, like the dielectric layer 20, the mask layer 30 may be provided on at least one of the principal surfaces 10c and 10d of the anode 10 (the principal surface on which the dielectric layer 20 is provided).

[0046] 15, the mask layer 30 is preferably provided so as to fill a plurality of pores (recesses) in the valve metal base 11. However, it is sufficient that the mask layer 30 covers a part of the outer surface of the dielectric layer 20, and there may be pores (recesses) in the valve metal base 11 that are not filled with the mask layer 30.

[0047] The mask layer 30 is made of an insulating material. The mask layer 30 is formed by applying a mask material such as a composition containing an insulating resin. Examples of insulating resins include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, etc.), a composition of soluble polyimide siloxane and epoxy resin, polyimide resin, polyamide-imide resin, and derivatives or precursors thereof.

[0048] The mask material can be applied by, for example, screen printing, roller transfer, dispenser, inkjet printing, or the like.

[0049] The cathode 40 has a solid electrolyte layer 50 provided on the dielectric layer 20 and a conductive layer 60 provided on the solid electrolyte layer 50. The cathode 40 is provided on the dielectric layer 20 on the front end surface 10a side of the mask layer 30. That is, the cathode 40 is provided on the dielectric layer 20 in a region on the front end surface 10a side of the anode 10 that is partitioned by the mask layer 30.

[0050] The solid electrolyte layer 50 is provided on the dielectric layer 20. As shown in Fig. 15, the solid electrolyte layer 50 is preferably provided so as to fill a plurality of pores (recesses) in the valve metal substrate 11. However, it is sufficient that the solid electrolyte layer 50 covers a portion of the outer surface of the dielectric layer 20, and there may be pores (recesses) in the valve metal substrate 11 that are not filled with the solid electrolyte layer 50.

[0051] The solid electrolyte layer 50 is provided on the dielectric layer 20 on the front end surface 10a side of the mask layer 30. That is, the solid electrolyte layer 50 is provided on the dielectric layer 20 in the region on the front end surface 10a side of the anode 10 partitioned by the mask layer 30.

[0052] As described above, the solid electrolyte layer 50 includes a first layer 51 including a first conductive polymer, a second layer 52 including a second conductive polymer, and a third layer 53 including a third conductive polymer. The second layer 52 is disposed only in a partial region, not the entire area, within the plane of the solid electrolyte layer 50. In other words, the second layer 52 is unevenly distributed in the in-plane direction of the solid electrolyte layer 50, not in the thickness direction. On the other hand, the first layer 51 and the third layer 53 are at least disposed in an area of ​​the surface of the solid electrolyte layer 50 where the second layer 52 is not disposed. Therefore, the solid electrolyte layer 50 has at least one of the first layer 51 and the third layer 53 and the second layer 52 disposed in its surface.

[0053] 3 and other figures, the first layer 51 and the third layer 53 are disposed over the entire surface of the solid electrolyte layer 50, the second layer 52 is provided on the first layer 51, and the third layer 53 is provided on the first layer 51 and the second layer 52. In other words, the second layer 52 is disposed only in a portion of the area on the first layer 51, and the third layer 53 covers the second layer 52 and the first layer 51 in the area where the second layer 52 is not disposed.

[0054] In this way, by making the outermost surface of the solid electrolyte layer 50 the same material surface, in this case all the third layer 53, formation variation in subsequent processing (for example, the process of forming a carbon layer such as graphite) is reduced, and characteristic variation of the electrolytic capacitor element 1, particularly ESR variation, can be reduced.

[0055] The thicknesses of the first layer 51 and the third layer 53 are not particularly limited and may be, for example, approximately the same as the inner and outer layers of a typical solid electrolyte layer. Specifically, the maximum thickness of the first layer 51 is preferably 0.1 μm to 10 μm, more preferably 0.2 μm to 5 μm, and even more preferably 0.3 μm to 3 μm. The maximum thickness of the third layer 53 is preferably 2 μm to 50 μm, more preferably 3 μm to 40 μm, and even more preferably 5 μm to 30 μm.

[0056] The thickness of the second layer 52 is also not particularly limited, but specifically, the maximum thickness of the second layer 52 is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 40 μm or less, and even more preferably 3 μm or more and 30 μm or less. The total thickness of the first layer 51, the second layer 52, and the third layer 53, that is, the thickness of the solid electrolyte layer 50, is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 25 μm or less.

[0057] The location where the second layer 52 is arranged can be set as appropriate, but as described above, the following are preferred: (1) a configuration in which the second layer 52 covers each corner 10g of the anode 10 (see Figure 3, etc.); (2) a configuration in which the second layer 52 further covers the tip surface 10a of the anode 10 and each ridge portion 10h formed by the tip surface 10a (see Figure 6, etc.); (3) a configuration in which the second layer 52 further covers each side surface 10e, 10f of the anode 10 and each ridge portion 10j formed by each side surface 10e, 10f (see Figure 9, etc.); or (4) a configuration in which the second layer 52 is arranged along the mask layer 30 (see Figure 12, etc.).

[0058] In the case of (1), the second layer 52 may cover at least one of the four corners 10g of the tip surface 10a, but it is preferable that the second layer 52 cover each of the four corners 10g. 3 shows a case where two corners 10g formed by the same side surface 10e or 10f (corners 10g arranged vertically in FIG. 3) are each independently covered by the second layer 52, but these two corners 10g may be integrally covered by the second layer 52. That is, the four ridges 10h formed by the tip surface 10a include two ridges 10ha formed by the side surface 10e or 10f and the tip surface 10a, but the second layer 52 may further cover the ridges 10ha.

[0059] In the case of (2), the second layer 52 may cover at least one of the four ridges 10h formed by the tip surface 10a, but preferably covers each of the four ridges 10h. In this way, the second layer 52 preferably covers the tip portion of the anode 10 (a portion including the tip surface 10a), and is preferably provided from the tip surface 10a to each of the main surface 10c, the main surface 10d, the side surface 10e, and the side surface 10f.

[0060] In the case of (3), the second layer 52 may cover at least one of the two side surfaces 10e and 10f, but preferably covers both of the two side surfaces 10e and 10f. Also, the second layer 52 may cover at least one of the four ridges 10j formed by the side surfaces 10e and 10f, but preferably covers all of the four ridges 10j. In this case, the second layer 52 does not have to cover the tip surface 10a and the ridges 10h formed by the tip surface 10a.

[0061] In the case of (4), the second layer 52 may be arranged along the mask layer 30 on at least one of the main surfaces 10c and 10d and the side surfaces 10e and 10f of the anode 10, but it is preferable that the second layer 52 be arranged along the mask layer 30 on each of these surfaces. In this case, it is preferable that there is no gap between the second layer 52 and the mask layer 30, and that the second layer 52 is arranged alongside the mask layer 30 while in contact with the mask layer 30. Furthermore, although a gap may occur between the first layer 51 and the mask layer 30 if only the first layer 51 is provided, it is preferable that the second layer 52 fills the gap between the first layer 51 and the mask layer 30 .

[0062] In either case, the shape of the second layer 52 is not particularly limited, and examples include a shape in which the peripheral contour line is composed of multiple straight lines that intersect at right angles as shown in Figure 3, a shape in which at least two of the straight lines of the peripheral contour line intersect at an angle, and a shape in which at least one of the straight lines of the peripheral contour line is curved.

[0063] Examples of materials that can be used to form the solid electrolyte layer 50 include conductive polymers having a main chain, such as polypyrrole, polythiophene, and polyaniline. Among these, polythiophene is preferred, and poly(3,4-ethylenedioxythiophene), also known as PEDOT, is particularly preferred. The conductive polymers contain a dopant, such as polystyrene sulfonate (PSS).

[0064] At least a portion of the solid electrolyte layer 50, specifically the second layer 52, contains a binder component. On the other hand, the first layer 51 and the third layer 53 may each contain a binder component. In that case, the content of the binder component contained in each of the first layer 51 and the third layer 53 is preferably less than the content of the binder component contained in the second layer 52. It is more preferable that the first layer 51 and the third layer 53 do not contain a binder component. On the other hand, since the second layer 52 is partially disposed within the plane of the solid electrolyte layer 50, the content of the binder component can be made larger than before.

[0065] More specifically, the content of the binder component in the first layer 51 or the third layer 53 is preferably 0.1 wt % or less, more preferably 0.05 wt % or less, and even more preferably 0.01 wt % or less. The content of the binder component in the second layer 52 is preferably 0.1 wt % to 20 wt % or less, more preferably 0.3 wt % to 10 wt % or less, and even more preferably 0.5 wt % to 5 wt %.

[0066] Specific examples of suitable binder components contained in the second layer 52 include polyisoprene, polystyrene, polyethylene, polyvinylpyrrolidone, polyvinyl alcohol, polymethyl methacrylate, polyacrylonitrile, polyester (preferably polyethylene terephthalate), polyamide, polyurethane, polycarbonate, cellulose, cellulose nanofiber, and polyphthalic acid ester. These may be used alone or in combination of two or more.

[0067] Suitable specific examples of binder components that can be contained in the first layer 51 and the third layer 53 include the same binder components as those contained in the second layer 52. These may be used alone or in combination of two or more.

[0068] There is a trade-off between the content of the binder component and the conductivity of the solid electrolyte layer 50. For example, the greater the content of the binder component, the lower the conductivity of the second layer 52. However, the first layer 51, the second layer 52, and the third layer 53 all function as conductive layers.

[0069] The solid electrolyte layer 50 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 of a conductive polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric layer 20 and drying it. In particular, the method of forming a polymerized film of a conductive polymer using a liquid containing a polymerizable monomer is more likely to result in a thinner solid electrolyte layer 50 on the corners 10g and ridges 10h and 10j of the anode 10 and on the regions around the mask layer 30 than a method using a dispersion of a conductive polymer, thereby more effectively suppressing leakage current.

[0070] More specifically, the first layer 51 and the third layer 53 are preferably formed by a method of forming a polymerized film of a conductive polymer such as poly(3,4-ethylenedioxythiophene) on the dielectric layer 20 using a liquid containing a polymerizable monomer such as 3,4-ethylenedioxythiophene.

[0071] On the other hand, the second layer 52 is preferably formed by, for example, a method of applying a dispersion of a conductive polymer containing a binder component onto the dielectric layer 20 and drying it. Here, since the second layer 52 contains a binder component and its conductivity is reduced, poly(3,4-ethylenedioxythiophene), which has excellent conductivity, is particularly suitable as the conductive polymer for the second layer 52. In this way, the first conductive polymer contained in the first layer 51, the second conductive polymer contained in the second layer 52, and the third conductive polymer contained in the third layer 53 may be the same conductive polymer (having the same main chain and dopant), or at least two of these conductive polymers may be different conductive polymers (having different at least one of the main chain and dopant).

[0072] The first layer 51 is preferably formed as an inner layer that fills the pores (recesses) of the valve metal substrate 11. The inner layer can be formed by, for example, a dipping method, sponge transfer, screen printing, a dispenser, inkjet printing, or the like.

[0073] Similarly, the second layer 52 can be formed by, for example, a dipping method, sponge transfer, screen printing, a dispenser, inkjet printing, etc., but in the cases of (1), (3), and (4) above, inkjet printing is preferred, and in the case of (2) above, a dipping method is preferred.

[0074] The third layer 53 is preferably formed as an outer layer that covers the entire dielectric layer 20. The outer layer can be formed by, for example, a dipping method, sponge transfer, screen printing, a dispenser, inkjet printing, or the like.

[0075] The conductive layer 60 is provided on the solid electrolyte layer 50. The conductive layer 60 covers substantially the entire area of ​​the solid electrolyte layer 50 and is in contact with the mask layer 30. The conductive layer 60 may be disposed up to just before the mask layer 30. The conductive layer 60 has a substantially constant thickness.

[0076] The conductive layer 60 includes, for example, a carbon layer or a cathode conductor layer. The conductive layer 60 may also be a composite layer in which a cathode conductor layer is provided on the outer surface of a carbon layer, or a mixed layer containing carbon and a cathode conductor layer material.

[0077] The carbon layer is formed, for example, by applying a carbon paste containing carbon particles and resin to the surface of the solid electrolyte layer 50 and drying it.

[0078] The carbon paste can be applied by, for example, a dipping method, sponge transfer, screen printing, spray application, a dispenser, inkjet printing, or the like.

[0079] The cathode conductor layer is formed, for example, by a method of applying a conductive paste containing metal particles such as gold, silver, copper, or platinum and a resin to the surface of the solid electrolyte layer or the carbon layer and drying the paste. The cathode conductor layer is preferably a silver layer.

[0080] The conductive paste can be applied by, for example, a dipping method, sponge transfer, screen printing, spray application, a dispenser, inkjet printing, or the like.

[0081] [Method of manufacturing electrolytic capacitor elements] The following describes a method for manufacturing the electrolytic capacitor element 1. In the following example, a method for simultaneously manufacturing a plurality of electrolytic capacitor elements using a large valve metal substrate will be described.

[0082] FIG. 16 is a schematic diagram showing an example of a step of preparing a valve metal substrate on which a mask layer is formed.

[0083] As shown in Fig. 16, a valve metal base 11A having a dielectric layer 20 on its surface is prepared. The valve metal base 11A includes a plurality of element portions 12 and a support portion 13. Each element portion 12 has a rectangular shape and protrudes from the support portion 13. A mask layer 30 is formed on the dielectric layer 20 of each element portion 12.

[0084] First, the valve metal substrate 11A having a porous portion on the surface is cut by laser processing, punching, or the like, to form a shape including a plurality of element portions 12 and support portions 13.

[0085] Next, a mask layer 30 is formed on both main surfaces and both side surfaces of each element portion 12 along the short sides of each element portion 12 .

[0086] Thereafter, the valve metal substrate 11A is anodized to form an oxide film that will become the dielectric layer 20 on the surface of the valve metal substrate 11A. At this time, an oxide film is also formed on the side surfaces of the element portions 12 that have been cut by laser processing, punching, or the like. Note that a chemically formed foil on which an oxide of the valve metal has already been formed may also be used as the valve metal substrate 11A. In this case, an oxide film is also formed on the side surfaces of the cut element portions 12 by anodizing the valve metal substrate 11A after cutting.

[0087] FIG. 17 is a schematic view showing an example of a process for forming the first and third layers of the solid electrolyte layer.

[0088] A first layer 51 (see FIG. 3, etc.) of the solid electrolyte layer 50 is formed on the dielectric layer 20 of the element section 12. As shown in FIG. 17, the treatment liquid for forming the first layer 51 is preferably applied to the valve metal base 11A by a dipping method. FIG. 17 shows a state in which a treatment liquid 70 for forming the first layer 51 or a treatment liquid 72 for forming the third layer 53 is supplied to a treatment tank 75.

[0089] The treatment liquid 70 for forming the first layer 51 may be, for example, a liquid containing a polymerizable monomer, such as 3,4-ethylenedioxythiophene, and an oxidant, such as iron(III) paratoluenesulfonate. The liquid containing the polymerizable monomer may be applied to the outer surface of the dielectric layer 20, and a film containing the first conductive polymer may be formed by chemical polymerization. Alternatively, the treatment liquid 70 for forming the first layer 51 may be a dispersion liquid of the first conductive polymer. The dispersion liquid of the first conductive polymer may be applied to the outer surface of the dielectric layer 20 and dried to form a conductive polymer film. This conductive polymer film becomes the first layer 51 of the solid electrolyte layer 50.

[0090] The treatment liquid 70 for forming the first layer 51 may contain the binder component described above, but preferably does not contain a binder component. If the treatment liquid 70 contains a binder component, the concentration of the binder component in the treatment liquid 70 is preferably 0.1 wt % or less, more preferably 0.05 wt % or less, and even more preferably 0.01 wt % or less.

[0091] 17, the valve metal substrate 11A is immersed in a treatment liquid 70, whereby the treatment liquid 70 is impregnated into the porous portion of the valve metal substrate 11A. After immersion for a predetermined time, the valve metal substrate 11A is removed from the treatment liquid 70 and dried at a predetermined temperature for a predetermined time. The process of immersion in the treatment liquid 70, removal, and drying may be repeated a predetermined number of times. As a result, the first layer 51 of the solid electrolyte layer 50 is formed.

[0092] For example, the valve metal substrate 11A is immersed in a liquid containing a polymerizable monomer (which may be a dispersion liquid containing a first conductive polymer), pulled out, and then dried to form the first layer 51 as an inner layer (a portion provided on the dielectric layer 20 and filling the pores of the valve metal substrate 11) of the solid electrolyte layer 50. The immersion in the liquid containing a polymerizable monomer, the pulling out, and the drying may be performed multiple times.

[0093] After forming the first layer 51, a primer layer may be formed by immersing the valve metal substrate 11A in a solution containing a primer compound, lifting it out, and drying it. When the primer layer is formed, the valve metal substrate 11A is washed with pure water to remove excess primer compound. After washing, a drying process is performed.

[0094] FIG. 18 is a schematic view showing an example of a step of forming the second layer of the solid electrolyte layer.

[0095] After forming the first layer 51 of the solid electrolyte layer 50, the second layer 52 (see FIG. 6, etc.) of the solid electrolyte layer 50 is formed on the first layer 51. For example, as shown in FIG. 18, a treatment liquid for forming the second layer 52 is applied to the first layer 51 by a dipping method. FIG. 18 shows a state in which a treatment liquid 71 for forming the second layer 52 is supplied to a treatment tank 76.

[0096] The treatment liquid 71 for forming the second layer 52 may be, for example, a dispersion of a second conductive polymer containing a binder component. By applying this dispersion to the outer surface of the first layer 51 and drying it, a conductive polymer film containing the binder component can be formed. Alternatively, the treatment liquid 71 for forming the second layer 52 may be a liquid containing a polymerizable monomer, such as 3,4-ethylenedioxythiophene, an oxidizing agent, such as iron (III) paratoluenesulfonate, and a binder component. By applying a liquid containing a polymerizable monomer containing a binder component to the outer surface of the first layer 51, a conductive polymer film containing the binder component can be formed by chemical polymerization. This conductive polymer film containing the binder component becomes the second layer 52 of the solid electrolyte layer 50.

[0097] The concentration of the binder component in the treatment liquid 71 is preferably 0.1% by weight or more and 20% by weight or less, more preferably 0.3% by weight or more and 10% by weight or less, and even more preferably 0.5% by weight or more and 5% by weight or less.

[0098] As shown in Figure 18, by immersing the tip of the valve metal substrate 11A in the treatment liquid 71, the treatment liquid 71 adheres to the outer surface of the first layer 51. After immersion for a predetermined time, the valve metal substrate 11A is pulled out of the treatment liquid 71 and dried at a predetermined temperature for a predetermined time. The process of immersion in the treatment liquid 71, pulling out, and drying may be repeated a predetermined number of times. As a result, the second layer 52 of the solid electrolyte layer 50 as shown in Figure 6 is formed.

[0099] Alternatively, a treatment liquid for forming the second layer 52 (for example, a dispersion liquid of the second conductive polymer or a liquid containing a polymerizable monomer) may be ejected onto the outer surface of the first layer 51 by inkjet printing to form the second layer 52 of the solid electrolyte layer 50 in a predetermined region. This allows the second layer 52 of the solid electrolyte layer 50 to be formed as shown in FIGS. 3, 9, and 12.

[0100] After forming the second layer 52 of the solid electrolyte layer 50, the third layer 53 (see FIG. 3, etc.) of the solid electrolyte layer 50 is formed on the first layer 51 and the second layer 52. For example, as shown in FIG. 17, it is preferable to apply a treatment liquid 72 for forming the third layer 53 to the first layer 51 and the second layer 52 by a dipping method.

[0101] The treatment liquid 72 for forming the third layer 53 may be, for example, a liquid containing a polymerizable monomer, such as 3,4-ethylenedioxythiophene, and an oxidant, such as iron(III) paratoluenesulfonate. The liquid containing the polymerizable monomer may be applied to the outer surfaces of the first layer 51 and the second layer 52, and a film containing a third conductive polymer may be formed by chemical polymerization. Alternatively, the treatment liquid 72 for forming the third layer 53 may be a dispersion of a third conductive polymer. A conductive polymer film may be formed by applying the dispersion of the third conductive polymer to the outer surfaces of the first layer 51 and the second layer 52 and drying the dispersion. This conductive polymer film becomes the third layer 53 of the solid electrolyte layer 50.

[0102] The treatment liquid 72 for forming the third layer 53 may contain the binder component described above, but preferably does not contain a binder component. If the treatment liquid 72 contains a binder component, the concentration of the binder component in the treatment liquid 72 is preferably 0.1 wt % or less, more preferably 0.05 wt % or less, and even more preferably 0.01 wt % or less.

[0103] 17, by immersing the valve metal substrate 11A in the treatment liquid 72, the treatment liquid 72 adheres to the outer surfaces of the first layer 51 and the second layer 52. After immersion for a predetermined time, the valve metal substrate 11A is removed from the treatment liquid 72 and dried at a predetermined temperature for a predetermined time. The process of immersion in the treatment liquid 72, removal, and drying may be repeated a predetermined number of times. As a result, the third layer 53 of the solid electrolyte layer 50 is formed.

[0104] For example, the valve metal substrate 11A is immersed in a liquid containing a polymerizable monomer (which may be a dispersion liquid containing a third conductive polymer), pulled out, and then dried to form the third layer 53 as the outer layer (the portion connected to the inner layer and covering the entire dielectric layer 20) of the solid electrolyte layer 50. The immersion in the liquid containing a polymerizable monomer, the pull-out, and the drying may be performed multiple times.

[0105] In this manner, the first layer 51, the second layer 52, and the third layer 53 of the solid electrolyte layer 50 are formed in predetermined regions.

[0106] After the solid electrolyte layer 50 is formed, the valve metal substrate 11A is immersed in the carbon paste, pulled out, and dried to form a carbon layer in a predetermined region.

[0107] After the carbon layer is formed, the valve metal substrate 11A is immersed in a conductive paste containing metal particles such as silver paste, and then pulled out and dried to form a cathode conductor layer in a predetermined region.

[0108] Then, the valve metal substrate 11A is cut to separate the element portion 12, and the strip-shaped anode 10 is formed, with the cut surface serving as the base end surface 10b.

[0109] Through the above steps, the electrolytic capacitor element 1 is obtained.

[0110] [Electrolytic capacitor] An example of an electrolytic capacitor including the electrolytic capacitor element of the present invention will be described below. The electrolytic capacitor element of the present invention may be included in an electrolytic capacitor having a different configuration. For example, a lead frame may be used as an external electrode. The electrolytic capacitor may also include an electrolytic capacitor element other than the electrolytic capacitor element of the present invention (i.e., an electrolytic capacitor element having a structure different from that of the electrolytic capacitor element of the present invention).

[0111] Fig. 19 is a perspective view schematically illustrating an example of an electrolytic capacitor including an electrolytic capacitor element according to an embodiment of the present invention, and Fig. 20 is a cross-sectional view taken along line ZZ of the electrolytic capacitor shown in Fig. 19.

[0112] 19 and 20, the length direction of the electrolytic capacitor 100 and the exterior package 110 is indicated by L, the width direction is indicated by W, and the height direction is indicated by T. Here, the length direction L, the width direction W, and the height direction T are perpendicular to each other.

[0113] 19 and 20, the electrolytic capacitor 100 has a substantially rectangular parallelepiped outer shape. The electrolytic capacitor 100 is a solid electrolytic capacitor and includes an outer casing 110, a first external electrode 120, a second external electrode 130, and a plurality of electrolytic capacitor elements 1.

[0114] The exterior body 110 seals a plurality of electrolytic capacitor elements 1. That is, a plurality of electrolytic capacitor elements 1 are embedded in the exterior body 110. However, the exterior body 110 may seal a single electrolytic capacitor element 1. That is, a single electrolytic capacitor element 1 may be embedded inside the exterior body 110.

[0115] 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 the height direction T, a first side surface 110c and a second side surface 110d that face each other in the width direction W, and a first end surface 110e and a second end surface 110f that face each other in the length direction L.

[0116] As described above, exterior body 110 has a substantially rectangular parallelepiped outer shape, but it is preferable that the corners and ridges are rounded.

[0117] The exterior body 110 is made of, for example, a sealing resin.

[0118] The sealing resin contains at least a resin, and preferably contains a resin and a filler.

[0119] As the resin, epoxy resin, phenol resin, polyimide resin, silicone resin, polyamide resin, liquid crystal polymer, etc. are preferably used.

[0120] As the filler, silica particles, alumina particles, etc. are preferably used.

[0121] As the sealing resin, a material containing a solid epoxy resin, a phenolic resin, and silica particles is preferably used.

[0122] When a solid sealing resin is used, resin molding such as compression molding or transfer molding is preferably used, with compression molding being more preferred. When a liquid sealing resin is used, molding methods such as dispensing or printing are preferably used. Among these, compression molding is preferred to seal the periphery of the electrolytic capacitor element 1 with the sealing resin to form the exterior body 110.

[0123] 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 forms the second main surface 110b of the exterior body 110. The thickness of the substrate is, for example, 100 μm.

[0124] The multiple electrolytic capacitor elements 1 are stacked in the height direction T via a conductive adhesive 140. The extending direction of each of the multiple 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 electrolytic capacitor elements 1 are bonded to each other via the conductive adhesive 140.

[0125] The conductive adhesive 140 contains, for example, metal particles such as gold, silver, copper, platinum, etc., and resin, but here, silver is used as the metal particles and acrylic resin is used as the resin. Other examples of the resin contained in the conductive adhesive 140 include urethane resin, epoxy resin, polyimide resin, and phenol resin.

[0126] The first external electrode 120 is provided on the first end surface 110e of the exterior package 110. In Fig. 19, the first external electrode 120 is provided from the first end surface 110e of the exterior package 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 conductive layer 60 of the cathode 40 of the electrolytic capacitor element 1 exposed from the exterior package 110 at the first end surface 110e. The first external electrode 120 may be directly or indirectly connected to the conductive layer 60 at the first end surface 110e of the exterior package 110.

[0127] The second external electrode 130 is provided on the second end surface 110f of the package 110. In Fig. 19, the second external electrode 130 is provided from the second end surface 110f of the package 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 anode 10 (valve metal base 11) of the electrolytic capacitor element 1 exposed from the package 110 at the second end surface 110f. The second external electrode 130 may be directly or indirectly connected to the anode 10 (valve metal base 11) at the second end surface 110f of the package 110.

[0128] 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 coating method, a plating method, and a sputtering method.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] The resin component preferably contains an epoxy resin, a phenolic resin, or the like as a main component.

[0133] 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 these, 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.

[0134] When the first external electrode 120 has a resin electrode layer, the first external electrode 120 and the cathode conductor layer both contain a resin component, which increases the adhesion between the first external electrode 120 and the cathode conductor layer, thereby improving reliability.

[0135] 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, it is preferable to provide, in this order (or with some of the plating layers removed), a copper plating layer, a nickel plating layer, and a tin plating layer, for example.

[0136] 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 second external electrode 130 may have a resin electrode layer connected to the anode 10 (valve metal substrate 11) and an outer plating layer provided on the surface of the resin electrode layer. Alternatively, the second external electrode 130 may have an inner plating layer connected to the anode 10 (valve metal substrate 11), 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.

[0137] In the above embodiment, the first layer 51 and the third layer 53 are disposed over the entire surface of the solid electrolyte layer 50. However, at least one of the first layer 51 and the third layer 53 may be disposed partially over the surface of the solid electrolyte layer 50. That is, at least one of the first layer 51 and the third layer 53 may be selectively disposed only in an area of ​​the surface of the solid electrolyte layer 50 where the second layer 52 is not disposed. In this case, inkjet printing is a suitable method for forming the first layer 51 and / or the third layer 53.

[0138] Furthermore, in the above embodiment, the electrolytic capacitor element 1 is described as a solid electrolytic capacitor using a conductive polymer as the electrolyte material, but the electrolytic capacitor element of the present invention may also be a so-called hybrid electrolytic capacitor element that uses an electrolytic solution in addition to a solid electrolyte such as a conductive polymer as the electrolyte material.

[0139] In the above embodiment, the electrolytic capacitor element 1 is used in a chip-type electrolytic capacitor 100, but the electrolytic capacitor element of the present invention may be used by being embedded in a package substrate included in a semiconductor device. Here, an example of the semiconductor device is a semiconductor composite device in which a voltage regulator (voltage control device) and a load are mounted on a package substrate. [Example]

[0140] EXAMPLES Hereinafter, examples will be given that more specifically disclose the electrolytic capacitor element of the present invention, but the present invention is not limited to these examples.

[0141] Example 1 An aluminum foil having an etching layer on its surface was prepared as an anode (valve metal substrate), and was anodized by immersing it in an aqueous solution of ammonium adipate to form a dielectric layer on the surface of the aluminum foil.

[0142] Next, a composition consisting of a soluble polyimidesiloxane and an epoxy resin was roller-transferred onto the aluminum foil on the surface of which a dielectric layer was formed, thereby forming mask layers on both main surfaces and both side surfaces of the foil via the dielectric layer.

[0143] Next, the aluminum foil was immersed in a mixture of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, then pulled out and dried. This chemically polymerized 3,4-ethylenedioxythiophene on the dielectric layer, forming the first layer of the solid electrolyte layer on the dielectric layer.

[0144] Next, a PEDOT-PSS dispersion containing 5% by weight of polyester as a binder component was applied to only each corner of the aluminum foil by inkjet printing, and then dried to partially form a second layer of solid electrolyte on the first layer (see Figure 3). The PEDOT-PSS dispersion is an aqueous dispersion of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid.

[0145] Next, the aluminum foil was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, and then pulled out and dried. This chemically polymerized 3,4-ethylenedioxythiophene on the first and second layers, forming a third solid electrolyte layer on the first and second layers.

[0146] Next, a carbon layer and a silver layer were formed in this order to obtain an electrolytic capacitor element.

[0147] Four of the resulting electrolytic capacitor elements were stacked using a conductive adhesive to obtain a laminate. The laminate was then sealed using epoxy resin and diced using a dicer. A silver paste containing a resin component was then screen-printed onto the cathode and anode end faces of the sealed body to form external electrodes on the cathode and anode, yielding a finished electrolytic capacitor.

[0148] Example 2 A finished electrolytic capacitor was obtained in the same manner as in Example 1, except that the solid electrolyte layer was formed as follows.

[0149] Specifically, an aluminum foil with a dielectric layer formed on its surface was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, then pulled out and dried. This chemically polymerized 3,4-ethylenedioxythiophene on the dielectric layer, forming a first layer of a solid electrolyte layer on the dielectric layer.

[0150] Next, only the tip (bottom end) of the aluminum foil was immersed in a PEDOT-PSS dispersion containing 5 wt% polyester as a binder component, pulled out, and then dried to partially form a second layer of solid electrolyte on the first layer (see Figure 6).

[0151] Next, the aluminum foil was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, and then pulled out and dried. This chemically polymerized 3,4-ethylenedioxythiophene on the first and second layers, forming a third solid electrolyte layer on the first and second layers.

[0152] Example 3 A finished electrolytic capacitor was obtained in the same manner as in Example 1, except that the solid electrolyte layer was formed as follows.

[0153] Specifically, an aluminum foil with a dielectric layer formed on its surface was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, then pulled out and dried. This chemically polymerized 3,4-ethylenedioxythiophene on the dielectric layer, forming a first layer of a solid electrolyte layer on the dielectric layer.

[0154] Next, a PEDOT-PSS dispersion containing 5% by weight of polyester as a binder component was applied to the tip surface (bottom surface), each side surface, each corner, and each ridge of the aluminum foil by inkjet printing, and then dried to partially form a second layer of the solid electrolyte layer on the first layer (see Figure 9).

[0155] Next, the aluminum foil was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, and then pulled out and dried. This chemically polymerized 3,4-ethylenedioxythiophene on the first and second layers, forming a third solid electrolyte layer on the first and second layers.

[0156] (Comparative Example 1) A finished electrolytic capacitor was obtained in the same manner as in Example 1, except that the solid electrolyte layer was formed as follows.

[0157] That is, an aluminum foil having a dielectric layer formed on its surface was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, and then pulled out and dried, thereby forming a first layer of a solid electrolyte layer on the dielectric layer.

[0158] Next, without forming a second solid electrolyte layer, an aluminum foil was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, then pulled out and dried, thereby forming a third solid electrolyte layer on the first layer.

[0159] (Comparative Example 2) A finished electrolytic capacitor was obtained in the same manner as in Example 1, except that the solid electrolyte layer was formed as follows.

[0160] That is, an aluminum foil having a dielectric layer formed on its surface was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, and then pulled out and dried, thereby forming a first layer of a solid electrolyte layer on the dielectric layer.

[0161] Next, the first layer was immersed in a PEDOT-PSS dispersion containing 5% by weight of polyester as a binder component so as to cover the entire first layer, and then removed and dried to form a second layer of solid electrolyte over the entire area of ​​the first layer.

[0162] Next, an aluminum foil was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, then pulled out and dried to form a third layer of the solid electrolyte layer on the second layer.

[0163] (Comparative Example 3) A finished electrolytic capacitor was obtained in the same manner as in Example 1, except that the solid electrolyte layer was formed as follows.

[0164] That is, an aluminum foil having a dielectric layer formed on its surface was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, and then pulled out and dried, thereby forming a first layer of a solid electrolyte layer on the dielectric layer.

[0165] Next, only the tip (bottom end) of the aluminum foil was immersed in a polyimide resin solution, pulled up, and then dried to partially form an insulating layer on the first layer.

[0166] Next, the aluminum foil was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, then pulled out and dried, thereby forming a third layer of the solid electrolyte layer on the first layer and the insulating layer.

[0167] Comparative Example 4 A finished electrolytic capacitor was obtained in the same manner as in Example 1, except that the solid electrolyte layer was formed as follows.

[0168] That is, an aluminum foil having a dielectric layer formed on its surface was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, and then pulled out and dried, thereby forming a first layer of a solid electrolyte layer on the dielectric layer.

[0169] Next, only the tip (bottom end) of the aluminum foil was immersed in a PEDOT-PSS dispersion liquid that did not contain a binder component, and then pulled out and dried to partially form a second layer of solid electrolyte on the first layer.

[0170] Next, an aluminum foil was immersed in a mixed solution of iron(III) paratoluenesulfonate, 3,4-ethylenedioxythiophene, and 1-butanol up to just below the mask layer, then pulled out and dried, thereby forming a third layer of the solid electrolyte layer on the first and second layers.

[0171] The equivalent series resistance (ESR) and leakage current (LC) yield of the finished electrolytic capacitors obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated. The results are shown in Table 1 below. The ESR indicates a relative value to the ESR of the electrolytic capacitor obtained in Comparative Example 1.

[0172] [Table 1]

[0173] In Examples 1, 2, and 3, the dense second layer containing the binder component was formed only in areas where leakage current was likely to occur, such as the corners of the tip of the aluminum foil, and therefore the LC yield rate was improved compared to Comparative Example 1 and the ESR was reduced compared to Comparative Example 2. Example 2 had a reduced ESR compared to Comparative Example 3. Compared to Example 2, Comparative Example 4 had no binder component in the second layer, and therefore the LC yield rate was reduced.

[0174] FIG. 21 shows an SEM photograph of a cross section of the electrolytic capacitor of Example 1.

[0175] As shown in Figure 21, it was confirmed that the inclusion of a binder component made the second layer a denser film than the first and third layers. That is, in the cross-sectional photograph, the second layer was observed to have a smooth (film-like) surface. On the other hand, the first and third layers were observed to have rougher surfaces than the second layer. [Explanation of symbols]

[0176] 1. Electrolytic capacitor element 10 Anode 10a Tip surface 10b Proximal surface 10c, 10d main surface 10e, 10f side 10g corner 10h, 10ha, 10j ridgeline area 11, 11A Valve metal substrate 12 Element section 13 Support part 20 dielectric layer 30 mask layers 40 cathode 50 Solid electrolyte layer 51 1st layer 52 2nd layer 53 3rd layer 60 Conductive layer 70, 71, 72 Processing liquid 75, 76 Treatment tank 100 electrolytic capacitors 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 140 Conductive adhesive

Claims

1. an anode constructed from a valve metal substrate and having a distal end surface and a proximal end surface; a dielectric layer provided on at least one main surface of the anode excluding at least the base end surface; a mask layer made of an insulating material and provided on the dielectric layer along the base end surface; a cathode provided on the dielectric layer on the front end surface side of the mask layer, the cathode has a solid electrolyte layer provided on the dielectric layer and a conductive layer provided on the solid electrolyte layer, the solid electrolyte layer is provided on the dielectric layer and includes: a first layer including a first conductive polymer; a second layer including a second conductive polymer and a binder component; and a third layer provided on at least the first layer and including a third conductive polymer; the second layer is partially disposed within a plane of the solid electrolyte layer, The electrolytic capacitor element, wherein the first layer and the third layer are disposed at least in regions of the surface of the solid electrolyte layer where the second layer is not disposed.

2. 2. The electrolytic capacitor element according to claim 1, wherein the first layer and the third layer each have a smaller binder component than the second layer.

3. The electrolytic capacitor element according to claim 2 , wherein the first layer and the third layer each do not contain a binder component.

4. 3. The electrolytic capacitor element according to claim 1, wherein the binder component contained in the second layer includes at least one component selected from the group consisting of polyisoprene, polystyrene, polyethylene, polyvinylpyrrolidone, polyvinyl alcohol, polymethyl methacrylate, polyacrylonitrile, polyester, polyamide, polyurethane, polycarbonate, cellulose, cellulose nanofiber, and polyphthalic acid ester.

5. 3. The electrolytic capacitor element according to claim 1, wherein the second layer is a denser film than the first layer and the third layer.

6. an anode constructed from a valve metal substrate and having a distal end surface and a proximal end surface; a dielectric layer provided on at least one main surface of the anode excluding at least the base end surface; a mask layer made of an insulating material and provided on the dielectric layer along the base end surface; a cathode provided on the dielectric layer on the front end surface side of the mask layer, the cathode has a solid electrolyte layer provided on the dielectric layer and a conductive layer provided on the solid electrolyte layer, the solid electrolyte layer is provided on the dielectric layer and includes: a first layer including a first conductive polymer; a second layer including a second conductive polymer; and a third layer provided on at least the first layer and including a third conductive polymer; the second layer is partially disposed within a plane of the solid electrolyte layer, the first layer and the third layer are disposed at least in a region of the surface of the solid electrolyte layer where the second layer is not disposed, The electrolytic capacitor element, wherein the second layer is a denser film than the first layer and the third layer.

7. the anode has six surfaces, including the tip surface, the base surface, a pair of main surfaces, and a pair of side surfaces, and has a corner portion where three of the six surfaces intersect, and a ridge portion where two of the six surfaces intersect, The electrolytic capacitor element according to claim 1 or 6, wherein the second layer covers a corner portion formed by the tip surface.

8. The electrolytic capacitor element according to claim 7 , wherein the second layer further covers the tip surface and a ridge portion formed by the tip surface.

9. The electrolytic capacitor element according to claim 7 , wherein the second layer further covers the side surfaces and ridges formed by the side surfaces.

10. The electrolytic capacitor element according to claim 1 or 6, wherein the second layer is disposed along the mask layer.

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