Solid electrolytic capacitor element, solid electrolytic capacitor, and method for manufacturing solid electrolytic capacitor element

Abstract

A solid electrolytic capacitor element (1) includes an anode (10) composed of a valve action metal base (11) having a front end face (10a) and a base end face (10b); a dielectric layer (20) provided on at least one main face (10c, 10d) of the anode (10) except for the base end face (10b); a mask layer (30) composed of an insulating material provided on the dielectric layer (20) along the base end face (10b); and a cathode (40) provided on the dielectric layer (20) on the front end face (10a) side than the mask layer (30), the cathode (40) having a solid electrolyte layer (50) provided on the dielectric layer (20) and a conductive layer (60) provided on the solid electrolyte layer (50), the solid electrolyte layer (50) having a convex portion (51) along the mask layer (30), the maximum thickness (t1, t2) of the solid electrolyte layer (50) in the convex portion (51) being greater than the thickness of the solid electrolyte layer (50) in a remaining portion (52) other than the convex portion (51).

Description

Technical Field

[0001] This invention relates to solid electrolytic capacitor elements, solid electrolytic capacitors, and methods for manufacturing solid electrolytic capacitor elements. Background Technology

[0002] Patent Document 1 discloses a solid electrolytic capacitor element, which includes a mask portion (mask layer) for insulating the anode and cathode portions and preventing the solid electrolyte from creeping up, etc., and the thickness of the solid electrolyte layer at the periphery of the valve-acting metal porous substrate is greater than the thickness of the solid electrolyte layer at the center of the valve-acting metal porous substrate.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 01 / 75917 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] Regarding solid electrolytic capacitor elements, the solid electrolyte layer tends to thin out near the mask layer and is also easily subjected to stress. Therefore, the conductive layer on the solid electrolyte layer in this vicinity comes into contact with the dielectric layer, making leakage current prone to occur due to tunneling current. As a result, this can potentially lead to a decrease in withstand voltage and reflow soldering resistance. Furthermore, reflow soldering resistance refers to the finished solid electrolytic capacitor's resistance to stress during reflow soldering.

[0008] In contrast, as described in Patent Document 1, by increasing the thickness of the solid electrolyte layer at the periphery of the substrate, it is expected that the leakage current can be reduced.

[0009] However, in the solid electrolytic capacitor element described in Patent Document 1, if the thickness of the solid electrolyte layer at the periphery of the substrate continues to increase as a whole in order to further suppress the generation of leakage current, the thickness of the solid electrolytic capacitor element at the periphery of the substrate other than near the mask layer will also become too thick. When the solid electrolytic capacitor element is stacked and assembled into a solid electrolytic capacitor, the volumetric efficiency of the assembled solid electrolytic capacitor will deteriorate.

[0010] This invention was made to solve the aforementioned problems, and its object is to provide a thin solid electrolytic capacitor element and a method for manufacturing the solid electrolytic capacitor element, which can achieve excellent voltage withstand and reflow soldering resistance. Furthermore, the object of this invention is to provide a thin solid electrolytic capacitor with excellent voltage withstand and reflow soldering resistance.

[0011] Technical solutions for solving the problem

[0012] The solid electrolytic capacitor element of the present invention comprises: an anode, which is made of a valve-acting metal substrate and has a front end face and a base end face; a dielectric layer, which is disposed on at least one main surface of the anode, excluding the base end face; a mask layer, which is made of an insulating material and is disposed on the dielectric layer along the base end face; and a cathode, which is disposed on the dielectric layer on a side closer to the front end face than the mask layer. The cathode comprises: a solid electrolyte layer disposed on the dielectric layer; and a conductive layer disposed on the solid electrolyte layer. The solid electrolyte layer has a protrusion along the mask layer, and the maximum thickness of the solid electrolyte layer in the protrusion is greater than the thickness of the solid electrolyte layer in the remaining portion excluding the protrusion.

[0013] The solid electrolytic capacitor of the present invention comprises a laminate having a plurality of solid electrolytic capacitor elements of the present invention stacked on top of each other.

[0014] The method for manufacturing the solid electrolytic capacitor element of the present invention comprises: a first step, immersing the anode, on which the mask layer is formed on the dielectric layer, from the front end side into a processing liquid containing a solid electrolyte until it contacts the mask layer; and a second step, lifting the anode from the processing liquid and drying the processing liquid, wherein the anode is dried in a state inverted during immersion.

[0015] Invention Effects

[0016] According to the present invention, a thin solid electrolytic capacitor element capable of achieving excellent voltage withstand and reflow soldering resistance, as well as a method for manufacturing the solid electrolytic capacitor element, can be provided. Furthermore, according to the present invention, a thin solid electrolytic capacitor with excellent voltage withstand and reflow soldering resistance can be provided. Attached Figure Description

[0017] Figure 1 This is a top view schematically illustrating an example of a solid electrolytic capacitor element according to an embodiment of the present invention.

[0018] Figure 2 yes Figure 1 A cross-sectional view of the solid electrolytic capacitor element shown along line XX.

[0019] Figure 3 yes Figure 1 The solid electrolytic capacitor element shown is a cross-sectional view along the YY line.

[0020] Figure 4 It is Figure 2 An enlarged cross-sectional view of the base end of the solid electrolytic capacitor element shown.

[0021] Figure 5 It is Figure 2 The image shows an enlarged cross-sectional view of the mask layer portion of the solid electrolytic capacitor element.

[0022] Figure 6 This is a top view schematically illustrating an example of a solid electrolytic capacitor element according to another embodiment of the present invention.

[0023] Figure 7 yes Figure 6 A cross-sectional view of the solid electrolytic capacitor element shown along line XX.

[0024] Figure 8 yes Figure 6 The solid electrolytic capacitor element shown is a cross-sectional view along the YY line.

[0025] Figure 9 This is a cross-sectional view schematically illustrating an example of a solid electrolytic capacitor element according to another embodiment of the present invention.

[0026] Figure 10 This is a schematic diagram illustrating an example of a process in which an anode, to which a mask layer has been formed, is immersed in a processing solution containing a solid electrolyte.

[0027] Figure 11 This is a schematic diagram illustrating an example of a process of lifting the anode from the treatment solution and drying the treatment solution.

[0028] Figure 12 This is a schematic diagram illustrating another example of a process in which the anode is lifted from the treatment solution and the treatment solution is dried.

[0029] Figure 13 It is a schematic representation of the process. Figure 11 The diagram shows a top view of an example of a solid electrolytic capacitor element after the drying process has formed a solid electrolyte layer.

[0030] Figure 14 It is a schematic representation of the process. Figure 12 The diagram shows a top view of an example of a solid electrolytic capacitor element after the drying process has formed a solid electrolyte layer.

[0031] Figure 15 This is a schematic diagram illustrating an example of a process for preparing a valve-acting metal substrate to form a mask layer.

[0032] Figure 16 This is a schematic diagram illustrating an example of a process for forming a solid electrolyte layer.

[0033] Figure 17This is a perspective view schematically illustrating an example of a solid electrolytic capacitor according to an embodiment of the present invention.

[0034] Figure 18 yes Figure 17 The solid electrolytic capacitor shown is a cross-sectional view along the ZZ line.

[0035] Figure 19 This is a cross-sectional view schematically illustrating an example of a solid electrolytic capacitor according to another embodiment of the present invention.

[0036] Figure 20 This is a cross-sectional view schematically illustrating an example of a solid electrolytic capacitor according to another embodiment of the present invention. Detailed Implementation

[0037] The following describes the solid electrolytic capacitor element, the solid electrolytic capacitor, and the manufacturing method of the solid electrolytic capacitor element of the present invention.

[0038] However, the present invention is not limited to the following structures, and can be applied by appropriate modifications without changing the spirit of the invention. Furthermore, combining two or more of the preferred structures described below also constitutes the present invention.

[0039] Furthermore, the embodiments shown below are illustrative, and it is self-evident that partial substitutions or combinations of the structures shown in different embodiments are possible. In the various embodiments, repetitions of descriptions of common aspects are omitted, and only the differences are described.

[0040] Solid electrolytic capacitor elements

[0041] Figure 1 This is a top view schematically illustrating an example of a solid electrolytic capacitor element according to an embodiment of the present invention. Figure 2 yes Figure 1 A cross-sectional view of the solid electrolytic capacitor element shown along line XX. Figure 3 yes Figure 1 The solid electrolytic capacitor element shown is a cross-sectional view along the YY line. Figure 4 It is Figure 2 The image shows an enlarged cross-sectional view of the base end of a solid electrolytic capacitor element. Additionally, in... Figure 1 In the image, the conductive layer 60 of the cathode 40 is shown in dashed lines, and the state of the conductive layer 60 is shown through the image.

[0042] Figure 1 , Figure 2 , Figure 3 as well as Figure 4The solid electrolytic capacitor element 1 shown includes: an anode 10, which is made of a valve-acting metal substrate 11 and has a front end face 10a and a base end face 10b; a dielectric layer 20, which is disposed on the surface of the anode 10 except for the base end face 10b; a mask layer 30, which is made of an insulating material and is disposed on the dielectric layer 20 along the base end face 10b; and a cathode 40, which is disposed on the dielectric layer 20 on the side closer to the front end face 10a than the mask layer 30. The cathode 40 has a solid electrolyte layer 50 disposed on the dielectric layer 20 and a conductive layer 60 disposed on the solid electrolyte layer 50.

[0043] Furthermore, on one main surface 10c side of the anode 10, the solid electrolyte layer 50 has a protrusion 51a along the mask layer 30, and the maximum thickness t1 of the solid electrolyte layer 50 in the protrusion 51a (refer to...) Figure 4 It is thicker than the solid electrolyte layer 50 in the remaining portion 52a excluding the protrusion 51a.

[0044] Furthermore, on the other main surface 10d side of the anode 10, similarly, the solid electrolyte layer 50 has a protrusion 51b along the mask layer 30, the maximum thickness t2 of the solid electrolyte layer 50 in the protrusion 51b (refer to...). Figure 4 It is thicker than the solid electrolyte layer 50 in the remaining portion 52b excluding the protrusion 51b.

[0045] Therefore, the thickness of the solid electrolyte layer 50 can be increased selectively near the mask layer 30, while preventing excessive thickness in other areas. This effectively suppresses leakage current near the mask layer 30 and improves the volumetric efficiency of the solid electrolytic capacitor incorporating the solid electrolytic capacitor element 1 by reducing the overall thickness. Consequently, it achieves a balance between improved voltage withstand capability, reflow soldering resistance, and a thinner profile for the solid electrolytic capacitor.

[0046] In addition, in this specification, the term "protrusion" includes the protruding portion of the surface and the base portion that overlaps with the protruding portion.

[0047] Furthermore, the term "thickness of the solid electrolyte layer in the remaining portion" refers to the maximum thickness of the solid electrolyte layer in the remaining portion.

[0048] Furthermore, the region from the thickest portion 53a of the protrusion 51a to the base end 54 of the solid electrolyte layer 50 located on the base end face 10b side of the anode 10 is not covered by the conductive layer 60, and the region from the thickest portion 53b of the protrusion 51b to the base end 54 of the solid electrolyte layer 50 located on the base end face 10b side of the anode 10 is not covered by the conductive layer 60. That is, the conductive layer 60 is not further provided on the thickest portions 53a and 53b of the protrusions 51a and 51b, thus the overall thickness of the solid electrolytic capacitor element 1 can be more effectively suppressed. In addition, leakage current generated when the conductive layer 60 contacts the dielectric layer 20 across the mask layer 30 can be suppressed.

[0049] In addition, the thickest parts 53a and 53b are the parts where the thickness of the protrusions 51a and 51b becomes the greatest, respectively.

[0050] Furthermore, the thickness of the solid electrolytic capacitor element 1 in the remaining portions 52a and 52b does not exceed the thickness Tmax of the solid electrolytic capacitor element 1 in the thickest portions 53a and 53b. Therefore, the overall thickness of the solid electrolytic capacitor element 1 can be suppressed more effectively.

[0051] Furthermore, the remaining portions 52a and 52b are both flat portions. That is, the thickness of the remaining portions 52a and 52b is smaller than that of the protrusions 51a and 51b, respectively. Therefore, the conductive layer 60 can be selectively provided on the remaining portions 52a and 52b, which have relatively smaller thicknesses compared to the protrusions 51a and 51b, thus further suppressing the overall thickness of the solid electrolytic capacitor element 1. In addition, a large area can be provided on the flat remaining portions 52a and 52b to ensure space for the conductive adhesive.

[0052] The following is a detailed description of the structure of solid electrolytic capacitor element 1.

[0053] Furthermore, in this specification, when describing the structures present on each of the main surfaces 10c and 10d of the anode 10, if they are described separately, they are distinguished by the same reference numerals "a" or "b". If they are described without distinction, "a" and "b" are omitted and only the same reference numerals are used.

[0054] The anode 10 is a thin film (foil) that is quadrilateral in shape when viewed from above, formed by a valve-acting metal substrate 11, preferably rectangular in shape (strip-shaped) with a pair of long sides and a pair of short sides when viewed from above. The front end face 10a and the base end face 10b are end faces located on a pair of sides (preferably a pair of short sides) of the anode 10. The base end face 10b is an exposed end face not covered by the dielectric layer 20, exposed at one end face of the solid electrolytic capacitor, and connected to the external electrode described later. The anode 10 has a front end face 10a, a base end face 10b, main faces 10c and 10d, and side faces 10e and 10f.

[0055] Additionally, in this specification, "top view" means viewing from the normal direction of the principal surface of the anode (valve-acting metal substrate).

[0056] Figure 5 It is Figure 2 The image shows an enlarged cross-sectional view of the mask layer portion of the solid electrolytic capacitor element.

[0057] like Figure 5 As shown, multiple recesses are provided on each main surface of the valve-acting metal substrate 11 (anode 10). Therefore, each main surface of the valve-acting metal substrate 11 becomes porous. This increases the surface area of ​​the valve-acting metal substrate 11. Furthermore, it is not limited to the case where both main surfaces of the valve-acting metal substrate 11 are porous; it is also possible for only one of the two main surfaces of the valve-acting metal substrate 11 to be porous.

[0058] The valve-acting metal substrate 11 is composed of, for example, elemental metals such as aluminum, tantalum, niobium, titanium, zirconium, or alloys containing these metals. An oxide coating can be formed on the surface of the valve-acting metal.

[0059] In addition, the valve action metal substrate 11 only needs to include a core and a porous part provided on at least one main surface of the core. Valve action metal substrates with the surface of the metal foil etched or valve action metal substrates with porous micro-powder sintered bodies formed on the surface of the metal foil can be used appropriately.

[0060] Here, the dielectric layer 20 is provided on the surface of the anode 10, except for the base end face 10b. That is, the dielectric layer 20 is provided on the front end face 10a, the main faces 10c and 10d, and the side faces 10e and 10f of the anode 10, but is not provided on the base end face 10b of the anode 10.

[0061] However, the dielectric layer 20 only needs to be disposed on at least one of the main surfaces 10c and 10d of the anode 10, except for the base end face 10b.

[0062] The dielectric layer 20 is preferably composed of an oxide coating disposed on the surface of the valve-acting metal substrate 11. For example, the dielectric layer 20 is composed of aluminum oxide. As described later, the aluminum oxide is formed by anodizing the surface of the valve-acting metal substrate 11.

[0063] The mask layer 30 is a linear (extending in a strip-like) insulating member disposed on the dielectric layer 20 along the base end face 10b of the anode 10 (preferably along the short side of the anode 10), separating the anode 10 and the cathode 40 to ensure insulation between them. The anode 10 is divided by the mask layer 30 into a region on the base end face 10b side and a region on the front end face 10a side. Here, although the mask layer 30 is disposed with a given interval from the base end face 10b, it can also be disposed to the edge of the base end face 10b. Furthermore, although the mask layer 30 is disposed on the main surfaces 10c and 10d and the side surfaces 10e and 10f of the anode 10 across the dielectric layer 20, it is sufficient that it is disposed on at least one of the main surfaces 10c and 10d of the anode 10 (however, on the main surface where the dielectric layer 20 is disposed) in the same manner as the dielectric layer 20.

[0064] like Figure 5 As shown, the mask layer 30 is preferably configured to fill a plurality of pores (recesses) in the valve-acting metal substrate 11. However, it is also possible for pores (recesses) in the valve-acting metal substrate 11 not to be filled by the mask layer 30, as long as a portion of the outer surface of the dielectric layer 20 is covered by the mask layer 30.

[0065] The mask layer 30 is made of an insulating material. The mask layer 30 is formed, for example, by coating a mask material containing an insulating resin composition. Examples of insulating resins include polyphenylene sulfide (PPS), polyethersulfone (PES), cyanate ester resins, fluoropolymers (tetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, etc.), compositions containing soluble polyimide siloxanes and epoxy resins, polyimide resins, polyamide-imide resins, and their derivatives or precursors.

[0066] The application of mask materials can be carried out, for example, by screen printing, roller transfer, dispenser, inkjet printing, etc.

[0067] The cathode 40 has a solid electrolyte layer 50 disposed on the dielectric layer 20 and a conductive layer 60 disposed on the solid electrolyte layer 50. Furthermore, the cathode 40 is disposed on the dielectric layer 20 on the side closer to the front end face 10a than the mask layer 30. That is, it is disposed on the dielectric layer 20 in the region on the front end face 10a side of the anode 10, which is defined by the mask layer 30.

[0068] A solid electrolyte layer 50 is disposed on the dielectric layer 20. For example... Figure 5As shown, the solid electrolyte layer 50 is preferably configured to fill a plurality of pores (recesses) in the valve-acting metal substrate 11. However, it is permissible for pores (recesses) in the valve-acting metal substrate 11 not to be filled by the solid electrolyte layer 50, as long as a portion of the outer surface of the dielectric layer 20 is covered by the solid electrolyte layer 50.

[0069] The solid electrolyte layer 50 is disposed on the dielectric layer 20 on the side closer to the front end face 10a than the mask layer 30. That is, it is disposed on the dielectric layer 20 in the region on the front end face 10a side of the anode 10 defined by the mask layer 30.

[0070] The base end 54 of the solid electrolyte layer 50 is located on the outer main surface of the mask layer 30 (the main surface opposite to the anode 10). The solid electrolyte layer 50 can be configured as follows: Figure 4 The mask layer 30 can be configured to cover a portion of its outer main surface, or it can be configured to cover the entire outer main surface of the mask layer 30. Alternatively, the solid electrolyte layer 50 can be arranged in a state of contact with the mask layer 30, such that it does not cover the entire outer main surface of the mask layer 30.

[0071] The solid electrolyte layer 50 has a protrusion 51a along the mask layer 30 and a remaining portion 52a other than the protrusion 51a on one main surface 10c side of the anode 10, and a protrusion 51b along the mask layer 30 and a remaining portion 52b other than the protrusion 51b on the other main surface 10d side of the anode 10.

[0072] The protrusion 51 is a thick film portion where the solid electrolyte layer 50 partially thickens, and is formed in a straight line (strip shape) parallel to the mask layer 30. That is, the protrusion 51 is a straight convex strip portion.

[0073] Here, as Figure 4 As shown, when viewed in a direction orthogonal to the mask layer 30, the protrusion 51 has an arc-shaped surface, but it may also have a trapezoidal or triangular surface.

[0074] In contrast, the remaining portion 52 is a flat portion with a thickness that is approximately fixed within the plane. Therefore, in the solid electrolytic capacitor element 1, the thickness of the solid electrolyte layer 50 in the so-called remaining portion 52 is the thickness of the flat portion.

[0075] like Figure 2 As shown, when viewed in section in a direction orthogonal to the mask layer 30, the solid electrolyte layer 50 has a generally linearly symmetrical shape about the anode 10 as the axis of symmetry. That is, the protrusions 51a and 51b are of approximately the same shape, the remaining portions 52a and 52b are of approximately the same shape, and the thickest portions 53a and 53b are located at approximately the same positions on the anode 10.

[0076] On the main surface 10c side of the anode 10, the maximum thickness t1 of the solid electrolyte layer 50 in the protrusion 51a is greater than the thickness of the solid electrolyte layer 50 in the remaining portion 52a. Furthermore, on the main surface 10d side of the anode 10, the maximum thickness t2 of the solid electrolyte layer 50 in the protrusion 51b is greater than the thickness of the solid electrolyte layer 50 in the remaining portion 52b. That is, the solid electrolyte layer 50 becomes the thickest on the main surface 10c side of the anode 10 in the protrusion 51a along the mask layer 30, and on the main surface 10d side of the anode 10 in the protrusion 51b along the mask layer 30.

[0077] More specifically, the difference between the maximum thickness t1 of the solid electrolyte layer 50 in the protrusion 51a and the thickness of the solid electrolyte layer 50 in the remaining portion 52a (e.g., the center of the remaining portion 52a) is preferably 2 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and even more preferably 10 μm or more and 30 μm or less.

[0078] The difference between the maximum thickness t2 of the solid electrolyte layer 50 in the protrusion 51b and the thickness of the solid electrolyte layer 50 in the remaining portion 52b (e.g., the center of the remaining portion 52b) is also the same.

[0079] In addition, the so-called "thickness of the solid electrolyte layer" refers to the thickness in the normal direction of one principal surface of the anode.

[0080] As materials constituting the solid electrolyte layer 50, conductive polymers such as polypyrrole, polythiophene, and polyaniline can be used. Among these, polythiophene is preferred, and poly(3,4-ethylenedioxythiophene) known as PEDOT is particularly preferred. Furthermore, the aforementioned conductive polymers may also contain dopants such as polystyrene sulfonic acid (PSS).

[0081] The solid electrolyte layer 50 can be formed, for example, by the following methods: forming a polymer 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; applying a dispersion of a conductive polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric layer 20 and drying it; etc.

[0082] Furthermore, it is preferable to form an outer layer covering the entire dielectric layer 20 after forming an inner layer that fills the pores (recesses) of the valve-acting metal substrate 11. The inner layer can be formed, for example, by dip-dip method, sponge transfer, screen printing, dispenser, inkjet printing, etc. Similarly, the outer layer can be formed, for example, by dip-dip method, sponge transfer, screen printing, dispenser, inkjet printing, etc.

[0083] A conductive layer 60 is disposed on the solid electrolyte layer 50. The conductive layer 60 may be positioned in front of the thickest portion 53 of the protrusion 51, such as... Figure 4 As shown, it does not cover the entire protrusion 51. The conductive layer 60 has a generally fixed thickness.

[0084] The conductive layer 60 may include, for example, a carbon layer or a cathode conductor layer. Alternatively, the conductive layer 60 may be a composite layer in which a cathode conductor layer is disposed on the outer surface of the carbon layer, or a mixed layer comprising carbon and a cathode conductor layer material.

[0085] The carbon layer can be 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.

[0086] Carbon paste can be applied by methods such as dip-coating, sponge transfer, screen printing, spraying, dispensers, and inkjet printing.

[0087] The cathode conductor layer can be formed, for example, by applying a conductive paste containing metal particles such as gold, silver, copper, and platinum and resin to the surface of a solid electrolyte layer or a carbon layer and then drying it. A silver layer is preferred as the cathode conductor layer.

[0088] The application of conductive paste can be carried out by methods such as dipping, sponge transfer, screen printing, spraying, dispensing, and inkjet printing.

[0089] The thickness of the solid electrolytic capacitor element 1 in the remaining portions 52a and 52b does not exceed the thickness Tmax of the solid electrolytic capacitor element 1 in the thickest portions 53a and 53b. That is, the thickness of the solid electrolytic capacitor element 1 in the remaining portions 52a and 52b is smaller than or approximately the same as the thickness Tmax of the solid electrolytic capacitor element 1 in the thickest portions 53a and 53b.

[0090] In addition, when there are protrusions 51a and 51b on the two main surfaces of the anode 10, the thickness Tmax of the solid electrolytic capacitor element 1 in the thickest parts 53a and 53b can also be the interval between two planes that are parallel to the anode 10 and pass through the vertices of the thickest parts 53a and 53b respectively.

[0091] Figure 6 This is a top view schematically illustrating an example of a solid electrolytic capacitor element according to another embodiment of the present invention. Figure 7 yes Figure 6 A cross-sectional view of the solid electrolytic capacitor element shown along line XX. Figure 8 yes Figure 6 The image shows a cross-sectional view of a solid electrolytic capacitor element along the YY line. Additionally, in... Figure 6In the image, the conductive layer 60 of the cathode 40 is shown in dashed lines, and the state of the conductive layer 60 is shown through the image.

[0092] exist Figure 6 , Figure 7 as well as Figure 8 In the solid electrolytic capacitor element 2 shown, the solid electrolyte layer 50 has an outer peripheral portion 55a including a protrusion 51a and a central portion 56a surrounded by the outer peripheral portion 55a on one main surface 10c side of the anode 10. The thickness of the solid electrolyte layer 50 in the outer peripheral portion 55a is greater than the thickness of the solid electrolyte layer 50 in the central portion 56a.

[0093] Similarly, the solid electrolyte layer 50 has an outer peripheral portion 55b containing a protrusion 51b and a central portion 56b surrounded by the outer peripheral portion 55b on the other main surface 10d side of the anode 10, wherein the thickness of the solid electrolyte layer 50 in the outer peripheral portion 55b is greater than the thickness of the solid electrolyte layer 50 in the central portion 56b.

[0094] Therefore, the thickness of the solid electrolyte layer 50 can be increased at the end of the anode 10, where the solid electrolyte layer 50 is easily thinned and stress is easily applied, thereby reducing the leakage current at the end of the anode 10. In addition, it can prevent conductive adhesive from overflowing from the cathode 40.

[0095] Each of the outer peripheral portions 55a and 55b includes protrusions 51a and 51b along the mask layer 30 and U-shaped portions 57a and 57b that are generally U-shaped portions along the front end face 10a and side faces 10e and 10f of the anode 10. The thickness of the protrusions 51a and 51b is greater than the thickness of the U-shaped portions 57a and 57b.

[0096] Each U-shaped portion 57a ​​and 57b has the same cross-sectional shape as the protrusions 51a and 51b. When viewed in a direction orthogonal to the extension direction, it has an arc-shaped surface, but it may also have a trapezoidal or triangular surface.

[0097] In this way, the remaining portions 52a and 52b have U-shaped portions 57a and 57b respectively. Therefore, in the solid electrolytic capacitor element 2, the thickness of the solid electrolyte layer 50 in the so-called remaining portions 52a and 52b is the maximum thickness of the U-shaped portions 57a and 57b respectively.

[0098] Figure 9 This is a cross-sectional view schematically illustrating an example of a solid electrolytic capacitor element according to another embodiment of the present invention.

[0099] exist Figure 9In the solid electrolytic capacitor element 3 shown, similarly to the case of the solid electrolytic capacitor element 1, the solid electrolyte layer 50 has a protrusion 51a and a remaining portion 52a as a flat portion on one main surface 10c side of the anode 10, and a protrusion 51b and a remaining portion 52b as a flat portion on the other main surface 10d side of the anode 10. Therefore, in the solid electrolytic capacitor element 3, the thickness of the solid electrolyte layer 50 in each remaining portion 52a, 52b is the thickness of the flat portion.

[0100] On the other hand, in the solid electrolytic capacitor element 3, the conductive layer 60 has a protrusion 61a along the front end face 10a of the anode 10 and a remaining portion 62a other than the protrusion 61a on one main surface 10c side of the anode 10, and a protrusion 61b along the front end face 10a of the anode 10 and a remaining portion 62b other than the protrusion 61b on the other main surface 10d side of the anode 10.

[0101] The protrusions 61a and 61b are thick film portions where the conductive layer 60 partially thickens, and are formed in a straight line (strip shape) parallel to the front end face 10a of the anode 10. That is, the protrusions 61a and 61b are straight convex strip portions.

[0102] Here, as Figure 9 As shown, when viewed in section in a direction orthogonal to the front end face 10a of the anode 10, the protrusions 61a and 61b have arc-shaped surfaces, but they may also have trapezoidal or triangular surfaces.

[0103] Furthermore, in the solid electrolytic capacitor element 3, regarding the cathode 40 as a whole, which includes the solid electrolyte layer 50 and the conductive layer 60, each main surface 10c and 10d side of the anode 10 has a first protrusion (protrusion strip) along the mask layer 30, a second protrusion (protrusion strip) along the front end surface 10a of the anode 10, and a flat portion other than the first protrusion and the second protrusion. The thickness of the first protrusion and the second protrusion is greater than the thickness of the flat portion.

[0104] [Manufacturing Method of Solid Electrolytic Capacitor Element]

[0105] Solid electrolytic capacitor elements 1 to 3 can be manufactured by the following methods.

[0106] Figure 10 This is a schematic diagram illustrating an example of a process in which an anode, to which a mask layer has been formed, is immersed in a processing solution containing a solid electrolyte. Figure 11 This is a schematic diagram illustrating an example of a process of lifting the anode from the treatment solution and drying the treatment solution. Figure 12 This is a schematic diagram illustrating another example of a process in which the anode is lifted from the treatment solution and the treatment solution is dried. Figure 13 It is a schematic representation of the process. Figure 11The diagram shows a top view of an example of a solid electrolytic capacitor element after the drying process has formed a solid electrolyte layer. Figure 14 It is a schematic representation of the process. Figure 12 The diagram shows a top view of an example of a solid electrolytic capacitor element after the drying process has formed a solid electrolyte layer.

[0107] like Figure 10 As shown, firstly, the anode 10, on which a mask layer 30 is formed on the dielectric layer 20, is immersed from the front end face 10a side in a processing solution 70 containing a solid electrolyte until it comes into contact with the mask layer 30 (first step). Additionally, the processing solution 70 is supplied to a processing tank 75.

[0108] Next, the anode 10 is lifted from the treatment solution 70 and the treatment solution 70 is dried (step 2).

[0109] Moreover, in this second process, such as Figure 11 or Figure 12 As shown, the anode 10 is dried in the same state as during immersion, which is upside down. That is, the anode 10 is dried with its front end face 10a facing up and its base end face 10b facing down.

[0110] Therefore, as Figure 13 or Figure 14 As shown, a solid electrolyte layer 50 with a protrusion 51 along the mask layer 30 can be formed, and the maximum thickness of the solid electrolyte layer 50 in the protrusion 51 can be greater than the thickness of the solid electrolyte layer 50 in the remaining portion 52.

[0111] More in detail, such as Figure 13 As shown, due to gravity, the solid electrolyte layer 50 is formed to selectively thicken in the region adjacent to the mask layer 30, or as... Figure 14 As shown, due to the coagulation effect, the solid electrolyte layer 50 is formed such that only the outer peripheral portion 55 becomes thicker.

[0112] The specific form it takes depends on the viscosity, surface tension, contact angle, and other characteristics of the treatment fluid 70. Figure 11 In the case shown, it is possible to achieve the following Figure 13 As shown, the remaining portion 52 is set as a flat portion, in Figure 12 In the case shown, it is possible to achieve the following Figure 14 The thickness of the solid electrolyte layer 50 in the outer peripheral portion 55 is made greater than the thickness of the solid electrolyte layer 50 in the central portion 56.

[0113] The first and second steps can also be performed alternately multiple times. In this case, it is preferable to dry the anode 10 in the same upside-down state as during immersion in at least one of the multiple second steps, and more preferably to dry the anode 10 in the same upside-down state as during immersion in each of the multiple second steps.

[0114] This method is preferred when the inner and outer layers of the solid electrolyte layer 50 are formed as described above.

[0115] In addition, the treatment solution used to impregnate the anode 10 in multiple first processes can be the same type of treatment solution or different types of treatment solutions.

[0116] After the second step, the anode 10, after the treatment solution 70 has been dried, is immersed in conductive paste from the front end side, for example, until it comes into contact with the protrusion 51 (the area that does not reach the thickest part 53) (the third step).

[0117] Then, the anode 10 is lifted from the conductive paste and the conductive paste is allowed to dry (step 4).

[0118] Therefore, as Figure 2 as well as Figure 7 A conductive layer 60 with a substantially fixed thickness is formed as shown, or as... Figure 9 A conductive layer 60 is formed as shown, having a protrusion along the front end face 10a of the anode 10.

[0119] The manufacturing method of solid electrolytic capacitor element 1 will be described in more detail below. In the following example, a method for simultaneously manufacturing multiple solid electrolytic capacitor elements using a large-scale valve-acting metal substrate will be described.

[0120] Figure 15 This is a schematic diagram illustrating an example of a process for preparing a valve-acting metal substrate to form a mask layer.

[0121] like Figure 15 As shown, a valve-acting metal substrate 11A with a dielectric layer 20 on its surface is prepared. The valve-acting metal substrate 11A includes a plurality of element portions 12 and a support portion 13. Each element portion 12 is elongated and protrudes from the support portion 13. Furthermore, a mask layer 30 is formed on the dielectric layer 20 of each element portion 12.

[0122] First, the valve-acting metal substrate 11A, which has a porous surface, is cut by laser processing or punching, thereby forming a shape that includes multiple element parts 12 and support parts 13.

[0123] Next, a mask layer 30 is formed on the two main surfaces and two side surfaces of the component section 12, such that along the short side of each component section 12.

[0124] Then, the valve-acting metal substrate 11A is anodized, thereby forming an oxide coating that serves as the dielectric layer 20 on the surface of the valve-acting metal substrate 11A. At this time, an oxide coating is also formed on the side surface of the element portion 12, which has been cut by laser processing or punching. Alternatively, a chemically generated foil with an oxide of the valve-acting metal already formed on it can be used as the valve-acting metal substrate 11A. In this case, an oxide coating is also formed on the side surface of the cut element portion 12 by anodizing the cut valve-acting metal substrate 11A.

[0125] Figure 16 This is a schematic diagram illustrating an example of a process for forming a solid electrolyte layer.

[0126] A solid electrolyte layer 50 is formed on the dielectric layer 20 of the component section 12 (see reference). Figure 5 (etc.). For example Figure 16 As shown, the treatment solution containing solid electrolyte is preferably coated onto the valve-acting metal substrate 11A by an impregnation method. Figure 16 The diagram shows the state in which a treatment solution 70 containing a solid electrolyte is supplied to a treatment tank 75.

[0127] As the treatment liquid 70 containing a solid electrolyte, for example, a dispersion of a conductive polymer can be used. By attaching the dispersion of the conductive polymer to the outer surface of the dielectric layer 20 and drying it, a conductive polymer film can be formed. Alternatively, as the treatment liquid 70 containing a solid electrolyte, a liquid containing a polymerizable monomer (e.g., 3,4-ethylenedioxythiophene) and an oxidizing agent can also be used. The liquid containing the polymerizable monomer can be attached to the outer surface of the dielectric layer 20 and a conductive polymer film can be formed by chemical polymerization. This conductive polymer film becomes the solid electrolyte layer 50.

[0128] like Figure 16 As shown, the valve-acting metal substrate 11A is immersed in the processing liquid 70, thereby allowing the processing liquid 70 to penetrate into the porous portion of the valve-acting metal substrate 11A. After immersion for a given time, the valve-acting metal substrate 11A is removed from the processing liquid 70 and dried at a given temperature for a given time. By repeating the immersion, removal, and drying in the processing liquid 70 a given number of times, a solid electrolyte layer 50 is formed. During this process, the processing liquid 70 is dried in at least one drying cycle (preferably in all drying cycles) while the valve-acting metal substrate 11A is in an upside-down position during immersion (i.e., with the element portion 12 on top and the support portion 13 on the bottom).

[0129] For example, after immersing the valve-acting metal substrate 11A in a first dispersion containing a conductive polymer and then lifting it out, the valve-acting metal substrate 11A is dried while remaining in the upside-down state during immersion, thereby forming a first solid electrolyte layer. Multiple immersions, liftings, and drying processes in the first dispersion may also be performed.

[0130] Alternatively, after the first solid electrolyte layer is formed, the valve-acting metal substrate 11A can be immersed in a solution containing a primer compound, lifted out and dried to form a primer layer.

[0131] Then, after immersing the valve-acting metal substrate 11A in a second dispersion containing conductive polymers and lifting it out, the valve-acting metal substrate 11A is dried while in the state of being flipped up and down during immersion, thereby forming a second solid electrolyte layer.

[0132] The solid electrolyte layer formed by the above method includes a first solid electrolyte layer disposed on the dielectric layer and a second solid electrolyte layer disposed on the first solid electrolyte layer.

[0133] The valve-acting metal substrate 11A is cleaned with pure water to remove any remaining primer compound. After cleaning, it is dried. Through these steps, a solid electrolyte layer 50 is formed in the given area.

[0134] After the solid electrolyte layer 50 is formed, the valve-acting metal substrate 11A is immersed in carbon paste, lifted and dried, thereby forming a carbon layer in a given area.

[0135] After the carbon layer is formed, the valve-acting metal substrate 11A is immersed in a conductive paste containing metal particles, such as silver paste, lifted and dried, thereby forming a cathode conductor layer in a given area.

[0136] Then, the valve-acting metal substrate 11A is cut to separate the element part 12, forming an elongated anode 10 with the cut surface becoming the base end face 10b.

[0137] After the above processes, solid electrolytic capacitor elements 1 to 3 are obtained.

[0138] Solid electrolytic capacitors

[0139] Hereinafter, an example of a solid electrolytic capacitor incorporating the solid electrolytic capacitor element of the present invention will be described. Furthermore, the solid electrolytic capacitor element of the present invention may also be incorporated into solid electrolytic capacitors having other structures. For example, a lead frame may be used as the external electrode. Moreover, the solid electrolytic capacitor of the present invention may also include solid electrolytic capacitor elements other than those of the present invention.

[0140] Figure 17 This is a perspective view schematically illustrating an example of a solid electrolytic capacitor according to an embodiment of the present invention. Figure 18 yes Figure 17 The solid electrolytic capacitor shown is a cross-sectional view along the ZZ line.

[0141] exist Figure 17 as well as Figure 18 In the diagram, L represents the length of the solid electrolytic capacitor 100 and its outer casing 110, W represents the width, and T represents the height. Here, the length direction L, the width direction W, and the height direction T are orthogonal to each other.

[0142] like Figure 17 as well as Figure 18 As shown, the solid electrolytic capacitor 100 has a generally rectangular parallelepiped shape. The solid electrolytic capacitor 100 includes an outer casing 110, a first external electrode 120, a second external electrode 130, and a plurality of solid electrolytic capacitor elements 1.

[0143] The outer casing 110 seals multiple solid electrolytic capacitor elements 1. That is, multiple solid electrolytic capacitor elements 1 are embedded in the outer casing 110. Alternatively, the outer casing 110 can also seal a single solid electrolytic capacitor element 1. That is, a single solid electrolytic capacitor element 1 can be embedded inside the outer casing 110.

[0144] The outer casing 110 has a generally rectangular parallelepiped shape. The outer casing 110 has a first main surface 110a and a second main surface 110b opposite each other in the height direction T, a first side surface 110c and a second side surface 110d opposite each other in the width direction W, and a first end surface 110e and a second end surface 110f opposite each other in the length direction L.

[0145] As described above, the outer casing 110 has a generally rectangular shape, but preferably has rounded corners and edges. The corners are the parts where three faces of the outer casing 110 intersect, and the edges are the parts where two faces of the outer casing 110 intersect.

[0146] The outer casing 110 is made of, for example, sealing resin.

[0147] The sealing resin comprises at least resin, preferably resin and filler.

[0148] Preferred resins include epoxy resins, phenolic resins, polyimide resins, silicone resins, polyamide resins, and liquid crystal polymers.

[0149] As fillers, silica particles, bauxite particles, etc. are preferred.

[0150] As a sealing resin, materials containing solid epoxy resin, phenolic resin and silica particles are preferred.

[0151] When using a solid sealing resin, resin molding methods such as compression molding and transfer molding are preferred, and compression molding is even more preferred. Furthermore, when using a liquid sealing resin, molding methods such as dispenser molding and printing are preferred. Of these, it is particularly preferred to form the outer casing 110 by sealing the solid electrolytic capacitor element 1 with sealing resin using compression molding.

[0152] The outer casing 110 may also be composed of a substrate and a sealing resin disposed on the substrate. The substrate may be, for example, an insulating resin substrate such as a glass epoxy board. In this case, the bottom surface of the substrate forms the second main surface 110b of the outer casing 110. The thickness of the substrate may be, for example, 100 μm.

[0153] Multiple solid electrolytic capacitor elements 1 are stacked in the height direction T with conductive adhesive 140 as a barrier. The extension direction of each of the multiple solid electrolytic capacitor elements 1 is substantially parallel to the first main surface 110a and the second main surface 110b of the outer casing 110. The solid electrolytic capacitor elements 1 are bonded to each other via conductive adhesive 140.

[0154] The conductive adhesive 140 is disposed in the area sandwiched by the remaining portion 52 of the solid electrolyte layer 50 of the adjacent solid electrolytic capacitor element 1. In order to reduce the thickness of the outer casing 110 (the thickness of the solid electrolytic capacitor 100), it is preferable not to cover the thickest portion 53 of the solid electrolyte layer 50 of the adjacent solid electrolytic capacitor element 1, and preferably not disposed in the entire area sandwiched by the protrusion 51 of the solid electrolyte layer 50 of the adjacent solid electrolytic capacitor element 1.

[0155] The conductive adhesive 140 contains, for example, metal particles such as gold, silver, copper, and platinum, and a resin. Here, silver is used as the metal particles, and acrylic resin is used as the resin.

[0156] Other examples of resins included in the conductive adhesive 140 include, for example, polyurethane resin, epoxy resin, polyimide resin, phenolic resin, etc.

[0157] The first external electrode 120 is disposed on the first end face 110e of the outer casing 110. Figure 17In this embodiment, the first external electrode 120 is configured to extend from the first end face 110e of the outer casing 110 to the first main face 110a, the second main face 110b, the first side face 110c, and the second side face 110d, respectively. The first external electrode 120 is electrically connected in the first end face 110e to the conductive layer 60 of the cathode 40 of the solid electrolytic capacitor element 1 exposed from the outer casing 110. The first external electrode 120 can be directly connected to the conductive layer 60 in the first end face 110e of the outer casing 110, or it can be indirectly connected.

[0158] The second external electrode 130 is disposed on the second end face 110f of the outer casing 110. Figure 17 In this embodiment, the second external electrode 130 is configured to extend from the second end face 110f of the outer casing 110 to the first main face 110a, the second main face 110b, the first side face 110c, and the second side face 110d, respectively. The second external electrode 130 is electrically connected in the second end face 110f to the anode 10 (valve-acting metal substrate 11) of the solid electrolytic capacitor element 1 exposed from the outer casing 110. The second external electrode 130 can be directly connected to the anode 10 (valve-acting metal substrate 11) in the second end face 110f of the outer casing 110, or it can be indirectly connected.

[0159] The first external electrode 120 and the second external electrode 130 are preferably formed by at least one method selected from the group consisting of immersion coating, screen printing, transfer printing, inkjet printing, dispenser method, spraying, brush coating, drop casting, electrostatic coating, plating, and sputtering.

[0160] The first external electrode 120 preferably has a resin electrode layer comprising conductive and resin components. By including resin components in the first external electrode 120, the adhesion between the first external electrode 120 and the sealing resin of the outer casing 110 is improved, thereby increasing reliability.

[0161] The second external electrode 130 preferably has a resin electrode layer comprising conductive and resin components. By including resin components in the second external electrode 130, the adhesion between the second external electrode 130 and the sealing resin of the outer casing 110 is improved, thereby increasing reliability.

[0162] The conductive component preferably includes elemental metals such as silver, copper, nickel, and tin, or alloys containing at least one of these metals as the main component.

[0163] The resin composition preferably includes epoxy resin, phenolic resin, etc. as the main components.

[0164] The resin electrode layer can be formed by methods such as dip coating, screen printing, transfer printing, inkjet printing, dispenser method, spray plating, brush coating, drop casting, and electrostatic coating. Among these, a printed resin electrode layer formed by screen printing conductive paste is particularly preferred. When the resin electrode layer is formed by screen printing conductive paste, compared to the case where the resin electrode layer is formed by dip coating, the first external electrode 120 and the second external electrode 130 tend to become flatter. That is, the thickness of the first external electrode 120 and the second external electrode 130 tends to become more uniform.

[0165] When the first external electrode 120 has a resin electrode layer, since both the first external electrode 120 and the cathode conductor layer contain resin components, the adhesion between the first external electrode 120 and the cathode conductor layer is improved, thereby increasing reliability.

[0166] At least one of the first external electrode 120 and the second external electrode 130 may also have a so-called plating layer formed by a plating method. Examples of plating layers include zinc-silver-nickel layers, silver-nickel layers, nickel layers, zinc-nickel-gold layers, nickel-gold layers, zinc-nickel-copper layers, and nickel-copper layers. Preferably, copper plating layers, nickel plating layers, and tin plating layers are sequentially (or, except for a portion of the plating layers) provided on these plating layers.

[0167] At least one of the first external electrode 120 and the second external electrode 130 may simultaneously have a resin electrode layer and a plating layer. For example, the second external electrode 130 may also have a resin electrode layer connected to the anode 10 (valve-acting metal substrate 11) and an outer plating layer disposed on the surface of the resin electrode layer. Furthermore, the second external electrode 130 may also have an inner plating layer connected to the anode 10 (valve-acting metal substrate 11), a resin electrode layer configured to cover the inner plating layer, and an outer plating layer disposed on the surface of the resin electrode layer.

[0168] Figure 19 This is a cross-sectional view schematically illustrating an example of a solid electrolytic capacitor according to another embodiment of the present invention.

[0169] exist Figure 19 In the solid electrolytic capacitor 200 shown, a plurality of solid electrolytic capacitor elements 2 replace a plurality of solid electrolytic capacitor elements 1 and are stacked in the height direction T with a conductive adhesive 140 between them.

[0170] Figure 20 This is a cross-sectional view schematically illustrating an example of a solid electrolytic capacitor according to another embodiment of the present invention.

[0171] exist Figure 20In the solid electrolytic capacitor 300 shown, a plurality of solid electrolytic capacitor elements 3 replace a plurality of solid electrolytic capacitor elements 1 and are stacked in the height direction T with a conductive adhesive 140 between them.

[0172] Example

[0173] The following provides more specific embodiments of the solid electrolytic capacitor element, solid electrolytic capacitor, and method for manufacturing the solid electrolytic capacitor element according to the present invention. However, the present invention is not limited to these embodiments.

[0174] (Example 1-1)

[0175] As the anode (valve-acting metal substrate), an aluminum foil with an etched layer on its surface is prepared and immersed in an aqueous solution of ammonium adipate for anodizing treatment, thereby forming a dielectric layer on the surface of the aluminum foil.

[0176] Next, a composition comprising soluble polyimide siloxane and epoxy resin is transferred onto the anode roller where the dielectric layer has been formed, thereby forming a mask layer on the two main surfaces and two side surfaces of the anode across the dielectric layer.

[0177] Next, the component is immersed in an aqueous dispersion of PEDOT:PSS up to directly beneath the mask layer. After being lifted, it is dried by flipping it over in the direction of immersion, thereby forming a solid electrolyte layer on the dielectric layer. Figure 2 As shown, the solid electrolyte layer has protrusions along the mask layer on both main surfaces of the anode, with the remaining portion being flat. The maximum thickness of the solid electrolyte layer in the protrusions is 25 μm, and the thickness of the solid electrolyte layer in the remaining portion (particularly the front end side of the anode) is 5 μm. Furthermore, the thickness of the resulting element directly below the mask layer (i.e., the thickness in the thickest part of the protrusions) is 170 μm, and the thickness of the lower end of the resulting element (i.e., the thickness on the front end side of the anode) is 130 μm.

[0178] Next, the element is immersed in carbon paste until it no longer overlaps with the thickest part of the solid electrolyte layer directly below the mask layer (i.e., the thickest part of the protrusion). After lifting, it is dried in the same direction as the immersion to form a carbon layer. Then, the element is immersed in silver paste in the same way as the carbon layer to form a silver layer as the cathode conductor layer, thereby forming a conductive layer and obtaining a solid electrolytic capacitor element. The thickness of the obtained solid electrolytic capacitor element directly below the mask layer (the thickness in the thickest part of the protrusion of the solid electrolyte layer) is 170 μm, and the thickness of the lower end of the obtained solid electrolytic capacitor element (the thickness on the front end side of the anode) is 160 μm.

[0179] Four solid electrolytic capacitor elements were stacked using a conductive adhesive to form a laminate. The laminate was then sealed with epoxy resin and diced into individual units. Next, a resin-containing silver paste was screen-printed onto the cathode and anode sides of the diced outer casing (sealing body), thereby forming external electrodes at the cathode and anode, resulting in the finished solid electrolytic capacitor. The finished solid electrolytic capacitor has a thickness of 1110 μm in the height direction.

[0180] (Comparative Example 1)

[0181] Except that the solid electrolyte layer was dried without being flipped upside down as in Example 1-1, the finished solid electrolytic capacitor was obtained using the same method. At this time, the thickness of the solid electrolytic capacitor element directly below the mask layer was 125 μm, the thickness of the lower end of the solid electrolytic capacitor element (the thickness on the front end side of the anode) was 200 μm, and the thickness excluding the conductive layers (carbon layer and silver layer) at the lower end was 170 μm. Furthermore, the thickness of the finished solid electrolytic capacitor in the height direction was 1230 μm.

[0182] (Examples 1-2)

[0183] Except that, in Example 1-1, the conductive layers (carbon and silver layers) were formed to overlap with the thickest portion of the solid electrolyte layer directly beneath the mask layer, the finished solid electrolytic capacitor was obtained using the same method. At this time, the thickness of the solid electrolytic capacitor element directly beneath the mask layer (the thickness of the thickest portion of the protrusion of the solid electrolyte layer) was 190 μm, the thickness excluding the conductive layers (carbon and silver layers) directly beneath the mask layer was 170 μm, the thickness of the lower end of the solid electrolytic capacitor element (the thickness at the front end of the anode) was 160 μm, and the thickness excluding the conductive layers (carbon and silver layers) at the lower end was 130 μm. Furthermore, the thickness of the finished solid electrolytic capacitor in the height direction was 1190 μm.

[0184] In addition, in Examples 1-1, 1-2 and Comparative Example 1, the total thickness of the four components, the conductive adhesive (30 μm), the epoxy resin (400 μm), and the external electrode (20 μm) constitutes the thickness of the finished product.

[0185] For the solid electrolytic capacitors obtained in Examples 1-1, 1-2, and Comparative Example 1, the thickness in the height direction, withstand voltage, and short circuit after reflow soldering were evaluated. The results are shown in Table 1 below.

[0186] [Table 1]

[0187] Example 1-1 1110μm 40V 0 / 100 Comparative Example 1 1230μm 35V 3 / 100 Examples 1-2 1190μm 40V 0 / 100

[0188] In Examples 1-1 and 1-2, the solid electrolyte layer directly beneath the mask layer is thicker, thus increasing the pressure resistance and stress resistance during reflow soldering compared to Comparative Example 1. Furthermore, in Example 1-1, the thickest part of the solid electrolyte layer is not covered by the conductive layers (carbon and silver layers), thus enabling a reduction in the thickness of the finished product compared to Examples 1-2.

[0189] (Example 2-1)

[0190] As the anode (valve-acting metal substrate), an aluminum foil with an etched layer on its surface is prepared and immersed in an aqueous solution of ammonium adipate for anodizing treatment, thereby forming a dielectric layer on the surface of the aluminum foil.

[0191] Next, a mask layer was formed on the two main surfaces and two side surfaces of the anode.

[0192] Next, the component is immersed in a mixture of ferric p-toluenesulfonate (III), 3,4-ethylenedioxythiophene, and 1-butanol until it is directly below the mask layer. After being lifted, it is dried by flipping it over in the direction of immersion, thereby forming a solid electrolyte layer on the dielectric layer. Figure 7 As shown, the solid electrolyte layer has an outer peripheral portion comprising a protrusion along the mask layer on both main surfaces of the anode, and a central portion surrounded by the outer peripheral portion and thinner than the outer peripheral portion. The maximum thickness of the solid electrolyte layer in the protrusion of the outer peripheral portion is 20 μm, the thickness of the solid electrolyte layer in the front end portion of the anode in the outer peripheral portion is 10 μm, and the thickness of the solid electrolyte layer in the central portion is 5 μm. Furthermore, the thickness of the obtained element directly below the mask layer (i.e., the thickness in the thickest part of the protrusion) is 160 μm, the thickness of the lower end of the obtained element (i.e., the thickness on the front end side of the anode) is 140 μm, and the thickness of the central portion of the obtained element is 130 μm.

[0193] Next, the element is immersed in carbon paste until it no longer overlaps with the thickest part of the solid electrolyte layer directly below the mask layer (i.e., the thickest part of the protrusion). After lifting, it is dried in the same direction as the immersion, thus forming a carbon layer. Then, the element is immersed in silver paste in the same way as the carbon layer to form a silver layer as the cathode conductor layer, thereby forming a conductive layer, thus obtaining a solid electrolytic capacitor element. The thickness of the obtained solid electrolytic capacitor element directly below the mask layer (the thickness in the thickest part of the protrusion of the solid electrolyte layer) is 160 μm, the thickness of the lower end of the obtained solid electrolytic capacitor element (the thickness on the front end side of the anode) is 160 μm, and the thickness of the central portion of the obtained solid electrolytic capacitor element is 150 μm.

[0194] Four solid electrolytic capacitor elements were stacked using a conductive adhesive to form a laminate. The laminate was then sealed with epoxy resin and diced into individual units. Next, a resin-containing silver paste was screen-printed onto the cathode and anode sides of the diced outer casing (sealing body), thereby forming external electrodes at the cathode and anode, resulting in the finished solid electrolytic capacitor. The finished solid electrolytic capacitor has a thickness of 1070 μm in the height direction.

[0195] (Comparative Example 2)

[0196] Except that the solid electrolyte layer was dried without inverting it as in Example 2-1, the finished solid electrolytic capacitor was obtained using the same method. At this time, the thickness of the solid electrolytic capacitor element directly below the mask layer was 125 μm, the thickness of the lower end of the solid electrolytic capacitor element (the thickness on the front end side of the anode) was 190 μm, and the thickness excluding the conductive layers (carbon layer and silver layer) at the lower end was 160 μm. Furthermore, the thickness of the finished solid electrolytic capacitor in the height direction was 1190 μm.

[0197] (Example 2-2)

[0198] Except that, in Example 2-1, when forming the conductive layer (carbon layer and silver layer) to overlap with the thickest part of the solid electrolyte layer directly below the mask layer, the finished solid electrolytic capacitor was obtained using the same method. At this time, the thickness of the solid electrolytic capacitor element directly below the mask layer (the thickness of the thickest part of the protrusion of the solid electrolyte layer) is 180 μm, and the thickness excluding the conductive layer (carbon layer and silver layer) directly below the mask layer is 160 μm. The thickness of the lower end (thickness on the front end side of the anode) of the obtained solid electrolytic capacitor element is 160 μm, and the thickness excluding the conductive layer (carbon layer and silver layer) at the lower end is 140 μm. The thickness of the central portion of the obtained solid electrolytic capacitor element is 150 μm, and the thickness excluding the conductive layer (carbon layer and silver layer) at the central portion is 130 μm. Furthermore, the thickness of the finished solid electrolytic capacitor in the height direction is 1150 μm.

[0199] In addition, in Examples 2-1, 2-2 and Comparative Example 2, the total thickness of the four components, the conductive adhesive (30 μm), the epoxy resin (400 μm), and the external electrode (20 μm) constitutes the thickness of the finished product.

[0200] For the solid electrolytic capacitors obtained in Examples 2-1, 2-2, and Comparative Example 2, the thickness in the height direction, withstand voltage, and short circuit after reflow soldering were evaluated. The results are shown in Table 2 below.

[0201] [Table 2]

[0202] Example 2-1 1070μm 8V 0 / 100 Comparative Example 2 1190μm 6V 5 / 100 Example 2-2 1150μm 8V 0 / 100

[0203] In Examples 2-1 and 2-2, the thickness of the solid electrolyte layer under the mask layer is greater, thus increasing the withstand voltage and resistance to stress during reflow soldering compared to Comparative Example 2. In Example 2-1, the thickest part of the solid electrolyte layer is not covered by the conductive layers (carbon and silver layers), thus enabling further miniaturization of the finished product thickness compared to Example 2-2.

[0204] Explanation of reference numerals in the attached figures

[0205] 1, 2, 3: Solid electrolytic capacitor elements;

[0206] 10: Anode;

[0207] 10a: Front face;

[0208] 10b: Base end face;

[0209] 10c, 10d: Main face;

[0210] 10e, 10f: Side view;

[0211] 11, 11A: Valve-acting metal matrix;

[0212] 12: Components Section;

[0213] 13: Support section;

[0214] 20: Dielectric layer;

[0215] 30: Mask layer;

[0216] 40: Cathode;

[0217] 50: Solid electrolyte layer;

[0218] 51a, 51b, 51: convex part;

[0219] 52a, 52b, 52: The remaining parts;

[0220] 53a, 53b, 53: The thickest part;

[0221] 54: Base;

[0222] 55a, 55b, 55: peripheral portion;

[0223] 56a, 56b, 56: Central part;

[0224] 57a, 57b: U-shaped part;

[0225] 60: Conductive layer;

[0226] 61a, 61b: convex part;

[0227] 62a, 62b: The remaining parts;

[0228] 70: Treatment fluid;

[0229] 75: Processing tank;

[0230] 100, 200, 300: Solid electrolytic capacitors;

[0231] 110: Exterior body;

[0232] 110a: First principal face;

[0233] 110b: Second main face;

[0234] 110c: First side view;

[0235] 110d: Second side view;

[0236] 110e: First end face;

[0237] 110f: Second end face;

[0238] 120: First external electrode;

[0239] 130: Second external electrode;

[0240] 140: Conductive adhesive;

[0241] t1, t2: The maximum thickness of the solid electrolyte layer in the protrusion;

[0242] Tmax: The thickness of the solid electrolytic capacitor element in the thickest part.

Claims

1. A solid electrolytic capacitor element, comprising: The anode is composed of a valve-acting metal matrix and has a front end face and a base end face. A dielectric layer is disposed on at least one main surface of the anode, except for the base end face; A mask layer, made of insulating material, is disposed on the dielectric layer along the base end face; as well as The cathode is disposed on the dielectric layer on the side closer to the front end face than the mask layer. The cathode has: A solid electrolyte layer is disposed on the dielectric layer; as well as A conductive layer is disposed on the solid electrolyte layer. The solid electrolyte layer has a protrusion along the mask layer. The maximum thickness of the solid electrolyte layer in the protrusion is greater than the thickness of the solid electrolyte layer in the remaining portion excluding the protrusion. The region from the thickest part of the protrusion to the base end of the solid electrolyte layer located on the base end face side of the anode is not covered by the conductive layer.

2. The solid electrolytic capacitor element according to claim 1, wherein, The thickness of the solid electrolytic capacitor element in the remaining portion does not exceed the thickness of the solid electrolytic capacitor element in the thickest portion.

3. The solid electrolytic capacitor element according to claim 1 or 2, wherein, The remaining portion is the flat part.

4. The solid electrolytic capacitor element according to claim 1 or 2, wherein, The solid electrolyte layer has an outer peripheral portion including the protrusion and a central portion surrounded by the outer peripheral portion. The thickness of the solid electrolyte layer in the outer peripheral portion is greater than the thickness of the solid electrolyte layer in the central portion.

5. A solid electrolytic capacitor, comprising: A laminate having stacked solid electrolytic capacitor elements as described in any one of claims 1 to 4.

6. A method for manufacturing a solid electrolytic capacitor element, wherein the solid electrolytic capacitor element is the solid electrolytic capacitor element according to any one of claims 1 to 4, wherein, The method for manufacturing the solid electrolytic capacitor element includes: In the first step, the anode, on which the mask layer is formed on the dielectric layer, is immersed from the front end side in a processing solution containing a solid electrolyte until it comes into contact with the mask layer. as well as The second step involves lifting the anode from the treatment solution and drying the treatment solution. In the second step, the anode is dried while it is in the same state as when it was immersed, which is upside down.

7. The method for manufacturing a solid electrolytic capacitor element according to claim 6, wherein, The first and second processes are performed alternately multiple times. In at least one of the multiple second steps, the anode is dried in a state where it was flipped over during immersion.

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