Solid electrolytic capacitor

Abstract

A solid electrolytic capacitor with high tolerance to environmental changes is desired. The solid electrolytic capacitor comprises: a laminate (100) containing a plurality of stacked solid electrolytic capacitor elements (CE); an uppermost layer (20TOP) fixed to a first surface of the laminate (100); and a lowermost layer (20BTM) fixed to a second surface of the laminate (100). The uppermost layer (20TOP) comprises a first resin and a first glass cloth. The lowermost layer (20BTM) comprises a second resin and a second glass cloth.

Description

Technical Field

[0001] This disclosure relates to solid electrolytic capacitors. Background Technology

[0002] Patent document 1 discloses a solid electrolytic capacitor.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2019 / 087692 Summary of the Invention

[0006] The technical problem the invention aims to solve

[0007] We look forward to solid electrolytic capacitors that are highly resistant to environmental changes.

[0008] Means for solving technical problems

[0009] The solid electrolytic capacitor disclosed herein comprises: a laminate containing a plurality of stacked solid electrolytic capacitor elements; a first layer fixed to a first surface of the laminate; and a second layer fixed to a second surface of the laminate, the first layer comprising a first resin and a first glass cloth, and the second layer comprising a second resin and a second glass cloth.

[0010] Invention Effects

[0011] The solid electrolytic capacitor disclosed herein exhibits increased tolerance to environmental changes. Attached Figure Description

[0012] Figure 1 This is a diagram showing the longitudinal cross-sectional structure of a solid electrolytic capacitor.

[0013] Figure 2 This is a diagram showing the longitudinal cross-sectional structure of the elements of a solid electrolytic capacitor.

[0014] Figure 3 It is a diagram used to illustrate the layer structure of a solid electrolytic capacitor.

[0015] Figure 4 This is an enlarged view of the area near the second side electrode in the elements of a solid electrolytic capacitor.

[0016] Figure 5 (A) is a diagram showing the planar structure of a glass cloth containing YRN glass fibers. Figure 5 (B) is a diagram showing the longitudinal cross-sectional structure of the insulating layer (20) containing glass cloth. Figure 5 (C) is a cross-sectional view of the filament FIL perpendicular to the long side direction.

[0017] Figure 6 It is a chart showing the parameters of the elements that make up the insulating layer (the top layer).

[0018] Figure 7 It is a chart showing the parameters of the elements that make up the insulating layer (intermediate layer).

[0019] Figure 8 It is a chart showing the evaluation results of solid electrolytic capacitors when various parameters are used.

[0020] Figure 9 This is a diagram showing the longitudinal cross-sectional structure of the intermediate body of a solid electrolytic capacitor during the formation of the slot.

[0021] Figure 10 It is a planar photograph showing the structure (defective product) around the groove.

[0022] Figure 11 It is a flat photograph showing the structure around the groove (good product).

[0023] Figure 12 This is a microscope photograph showing the longitudinal cross-sectional structure of a solid electrolytic capacitor intermediate (defective product).

[0024] Figure 13 This is a microscope photograph showing the longitudinal cross-sectional structure of a solid electrolytic capacitor intermediate (good quality).

[0025] Symbol Explanation

[0026] 8……Anode electrode layer, 11……First insulating layer, 11B……Second insulating layer, 12……First solid electrolyte layer, 12B……Second solid electrolyte layer, 14……Upper cathode electrode layer (first cathode electrode layer), 14B……Lower cathode electrode layer (second cathode electrode layer), 30……Insulating part, 30U……Upper layer (first resin layer), 30M……Middle layer (intermediate resin layer), 30D……Lower layer (second resin layer), E1……First side electrode, E2……Second side electrode. Detailed Implementation

[0027] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. Furthermore, in each drawing, the same or equivalent parts are labeled with the same symbols, and repeated descriptions are omitted.

[0028] Figure 1 This is a diagram showing the longitudinal cross-sectional structure of a solid electrolytic capacitor.

[0029] The solid electrolytic capacitor includes: a bottom layer 20BTM serving as a support substrate, a laminate 100 including the support substrate, and protective insulators 16 disposed on the top surface and the sides of the laminate 100 where no electrodes are formed. An anode terminal 1 and a cathode terminal 2 are disposed on the lower surface of the support substrate. A first side electrode E1, electrically connected to the anode terminal 1, is disposed on a first side surface S1 of the laminate 100. A second side electrode E2, electrically connected to the cathode terminal 2, is disposed on a second side surface S2 of the laminate 100.

[0030] Establish a three-dimensional orthogonal coordinate system. The stacking direction of the solid electrolytic capacitor element CE in the laminate 100 is set as the Z-axis direction. The X-axis is perpendicular to the Z-axis and extends from the first side electrode E1 towards the second side electrode E2. The Y-axis is perpendicular to the Z-axis and also perpendicular to the X-axis. The first side electrode S1 is one YZ plane of the laminate 100, and the second side electrode S2 is the other YZ plane of the laminate 100.

[0031] The laminate 100 has multiple solid electrolytic capacitor elements CE and multiple insulating layers (20). The multiple insulating layers (20) include: a bottom layer 20BTM (20), a top layer 20TOP (20), and one or more intermediate layers 20.

[0032] The bottom layer 20BTM (20) forms a support substrate. The top layer 20TOP is disposed between the protective insulator 16 and the upper solid electrolytic capacitor element CE. A plurality of intermediate layers 20 include an intermediate layer 20 disposed between the bottom layer 20BTM and the lower solid electrolytic capacitor element, an intermediate layer 20 disposed between adjacent solid electrolytic capacitor elements CE in the thickness direction, and an intermediate layer 20 disposed between the top layer 20TOP and the upper solid electrolytic capacitor element CE.

[0033] The bottommost layer 20BTM also functions as a barrier layer to increase the mechanical strength of the solid electrolytic capacitor and protect the inner layers from external contaminants. The topmost layer 20TOP also functions as a barrier layer to increase the mechanical strength of the solid electrolytic capacitor and, together with the protective insulator 16, protect the inner layers from external contaminants. By having the bottommost layer 20BTM and the topmost layer 20TOP in the solid electrolytic capacitor, stress generated within the laminate due to environmental changes can be suppressed. Furthermore, by having one or more intermediate layers 20 in the solid electrolytic capacitor, stress generated within the laminate due to environmental changes can be further suppressed.

[0034] Two solid electrolytic capacitor elements CE (first solid electrolytic capacitor element CE1 and second solid electrolytic capacitor element CE2) are shown in the same figure. The number of solid electrolytic capacitor elements CE can be, for example, four or five, or more than two. Even when the number of solid electrolytic capacitor elements CE is increased, an intermediate layer 20 is disposed between adjacent solid electrolytic capacitor elements CE in the thickness direction.

[0035] Figure 2 This is a diagram showing the longitudinal cross-sectional structure of the element CE of a solid electrolytic capacitor.

[0036] A solid electrolytic capacitor element CE has an anode electrode layer 8.

[0037] The solid electrolytic capacitor element CE has an upper cathode electrode layer 14 and a solid electrolyte layer 12 disposed between the anode electrode layer 8 and the upper cathode electrode layer 14 (first cathode electrode layer) in the region above the anode electrode layer 8. The solid electrolyte layer 12 is composed of a roughened layer containing conductive polymers. In the region near the interface between the anode electrode layer 8 and the solid electrolyte layer 12, a dielectric layer 9 is formed along the uneven shape inside the roughened layer in the solid electrolyte layer 12. On the upper surface of the solid electrolyte layer 12, a residual conductive polymer layer that did not penetrate into the roughened layer when added may also be formed, and a first conductive layer 13 is formed in contact with the conductive polymer layer. The first conductive layer 13 can be formed not only on the upper surface of the solid electrolyte layer 12, but also on the upper surface 11S of a pair of first insulating layers 11 formed at both ends in the X-axis direction of the solid electrolytic capacitor element CE. The upper cathode electrode layer 14 is formed on the upper surface of the first conductive layer 13. A first protective layer 15 is formed on the surface above the upper cathode electrode layer 14.

[0038] On the upper side of the anode electrode layer 8, upper insulating regions 10, forming a pair of mixed regions, are formed near both ends in the X-axis direction. One upper insulating region 10 is located near the first side electrode E1. The other upper insulating region 10 is located near the second side electrode E2. A first insulating layer 11 is formed on the upper surface of each upper insulating region 10. An upper cathode electrode layer 14 is formed on the upper surface of the first insulating layer 11. The material of the pair of upper insulating regions 10 includes a first metal and a first resin. The first metal is aluminum constituting the roughening layer, and the first resin is a thermosetting resin such as epoxy resin.

[0039] The solid electrolytic capacitor element CE has a lower cathode electrode layer 14B (second cathode electrode layer) in the region below the anode electrode layer 8, and a second solid electrolyte layer 12B disposed between the anode electrode layer 8 and the lower cathode electrode layer 14B. The second solid electrolyte layer 12B is composed of a roughened layer containing conductive polymers. In the region near the interface between the anode electrode layer 8 and the second solid electrolyte layer 12B, a second dielectric layer 9B is formed along the uneven shape inside the roughened layer in the second solid electrolyte layer 12B. On the lower surface of the second solid electrolyte layer 12B, a residual conductive polymer layer that did not penetrate into the roughened layer when added may also be formed, and a second conductive layer 13B is formed in contact with the conductive polymer layer. The second conductive layer 13B can be formed not only on the lower surface of the solid electrolyte layer 12B, but also on the second surface 11SB below a pair of second insulating layers 11B, which are formed at both ends in the X-axis direction of the solid electrolytic capacitor element CE. A lower cathode electrode layer 14B is formed on the surface below the second conductive layer 13B. A second protective layer 15B is formed on the surface below the lower cathode electrode layer 14B.

[0040] In the lower region of the anode electrode layer 8, lower insulating regions 10B, which are a pair of mixed regions, are formed near both ends in the X-axis direction. One lower insulating region 10B is located near the first side electrode E1. The other lower insulating region 10B is located near the second side electrode E2. A second insulating layer 11B is formed on the lower surface of each lower insulating region 10B. A lower cathode electrode layer 14B is formed on the lower surface of the second insulating layer 11B. The material of the pair of lower insulating regions 10B includes the aforementioned first metal (a roughened layer made of aluminum) and a first resin (a thermosetting resin such as epoxy resin).

[0041] The first side electrode E1 is in contact with one side of the anode electrode layer 8 and is electrically connected to the anode terminal 1. The first side electrode E1 is not in contact with one side of the upper cathode electrode layer 14. The second side electrode E2 is in contact with the other side of the upper cathode electrode layer 14 and is electrically connected to the cathode terminal 2. The second side electrode E2 is not in contact with the other side of the anode electrode layer 8, and an insulating portion 30 is provided between the second side electrode E2 and the anode electrode layer 8.

[0042] The insulating portion 30 is made of the same material as the protective insulator 16, and preferably contains filler within a resin (e.g., epoxy resin). Furthermore, the insulating portion 30 has a three-layer structure consisting of an upper layer 30U, a middle layer 30M, and a lower layer 30D. The insulating portion 30 can also be a single-layer structure.

[0043] An example of the material for the anode electrode layer 8 is aluminum. An example of the material for the roughening layers formed on the upper and lower surfaces of the anode electrode layer 8 is aluminum. An example of the material for the dielectric layer 9 formed near the surface of the anode electrode layer 8 is aluminum oxide (Al₂O₃). An example of the material for the solid electrolyte layer 12 is a material into which a conductive polymer has been introduced into the aluminum roughening layer. An example of the material for the upper cathode electrode layer 14 is copper. The materials of the lower elements of the anode electrode layer 8 are the same as the corresponding materials of the upper elements.

[0044] The mixed region (insulating region (10, 10B)) of the first side electrode side and the second side electrode side contains a first metal (aluminum, etc.) and a first resin (thermosetting resin such as epoxy resin). The insulating layer (11, 11B) of the first side electrode side and the second side electrode side contains filler such as silica and resin (thermosetting resin such as epoxy resin).

[0045] The first side electrode E1 is in contact with the first side 81 of the anode electrode layer 8. The second side electrode E2 is in contact with the second side 82 of the anode electrode layer 8. The second side electrode E2 is electrically connected to the upper cathode electrode layer 14 and the lower cathode electrode layer 14B, but the mechanical toughness of this connection depends on the stress generated in the vicinity of the second side electrode E2.

[0046] Figure 3 It is a diagram used to illustrate the layer structure of a solid electrolytic capacitor.

[0047] In the layer structure on the anode connection side, between the protective insulator 16 and the lower solid electrolytic capacitor element CE, the following layers are arranged sequentially from top to bottom: an uppermost layer 20TOP, an intermediate layer 20, a first protective layer 15, an upper cathode electrode layer 14, a first insulating layer 11, an upper insulating region 10, an anode electrode layer 8, a lower insulating region 10B, a second insulating layer 11B, a lower cathode electrode layer 14B, a second protective layer 15B, and an intermediate layer 20. An intermediate layer 20 containing only resin is flowably disposed from the upper intermediate layer 20, adjacent to the anode connection side of the first protective layer 15 and the upper cathode electrode layer 14. Similarly, an intermediate layer 20 containing only resin is flowably disposed from the lower intermediate layer 20, adjacent to the anode connection side of the second protective layer 15B and the lower cathode electrode layer 14B. An intermediate layer 20 and a lowermost layer 20BTM are disposed at the bottom of the lower solid electrolytic capacitor element CE.

[0048] In the layered structure located in the central part between the anode connection side and the cathode connection side, between the protective insulator 16 and the lower solid electrolytic capacitor element CE, the following layers are arranged sequentially from top to bottom: uppermost layer 20TOP, intermediate layer 20, first protective layer 15, upper cathode electrode layer 14, first conductive layer 13, first solid electrolyte layer 12, first dielectric layer 9, anode electrode layer 8, second dielectric layer 9B, second solid electrolyte layer 12B, second conductive layer 13B, lower cathode electrode layer 14B, second protective layer 15B, and intermediate layer 20. The lower part of the lower solid electrolytic capacitor element CE has intermediate layer 20 and lowermost layer 20BTM.

[0049] In the layer structure on the cathode connection side, between the protective insulator 16 and the lower solid electrolytic capacitor element CE, the following layers are arranged sequentially from top to bottom: an uppermost layer 20TOP, an intermediate layer 20, a first protective layer 15, an upper cathode electrode layer 14, a first insulating layer 11, an upper insulating region 10, an anode electrode layer 8, a lower insulating region 10B, a second insulating layer 11B, a lower cathode electrode layer 14B, a second protective layer 15B, and an intermediate layer 20. An insulating portion 30 comprising resin and filler is disposed adjacent to the side of the upper insulating region 10 and the anode electrode layer 8 on the cathode connection side. The lower part of the lower solid electrolytic capacitor element CE is provided with an intermediate layer 20 and a lowermost layer 20BTM.

[0050] Next, the layer structure, materials, and dimensions of the cathode connection side will be further explained.

[0051] Figure 4 This is an enlarged view of the area near the second side electrode in the elements of a solid electrolytic capacitor.

[0052] An insulating portion 30 is disposed between the second side surface 82 of the anode electrode layer 8 and the second side electrode E2. The insulating portion 30 contains resin and may also contain filler. The second side surface 82 protrudes toward the second side electrode E2, and in the XZ cross section, the front end of the second side surface 82 tapers to have two sides forming an acute angle. Along the stacked structure passing through the Z-axis of the insulating portion 30, from top to bottom, there are an upper cathode electrode layer 14, a first insulating layer 11, an insulating portion 30, a second insulating layer 11B, and a lower cathode electrode layer 14B.

[0053] A first insulating layer 11 is disposed directly below the upper cathode electrode layer 14. In other words, the first insulating layer 11 is disposed between the upper cathode electrode layer 14 and the insulating portion 30. A second insulating layer 11B is disposed directly above the lower cathode electrode layer 14B. In other words, the second insulating layer 11B is disposed between the lower cathode electrode layer 14B and the insulating portion 30. In this example of a solid electrolytic capacitor, the adhesion strength between the upper cathode electrode layer 14 and the lower cathode electrode layer 14B and the second side electrode E2 is improved, while the adhesion strength outside these adhesion points is relatively reduced.

[0054] When environmental changes such as temperature variations occur and internal stress is generated, the parts with relatively low adhesive strength peel off due to internal stress, while the connection parts of the cathode electrode layer are protected from the effects of internal stress. Therefore, the solid electrolytic capacitor with this structure has increased tolerance to environmental changes.

[0055] In this example of a solid electrolytic capacitor, in Figure 1 In the laminated structure, a prepreg containing a mixture of resin and glass cloth can be used in the insulating layers constituting the middle layer 20, the uppermost layer 20TOP, and the lowermost layer 20BTM. In the solid electrolytic capacitor of this example, the use of prepreg increases its resistance to environmental changes.

[0056] The first insulating layer 11 and the second insulating layer 11B disposed near the cathode electrode layer respectively contain resin and filler to improve the adhesion strength near the cathode electrode layer.

[0057] The insulating portion 30 includes an upper layer 30U (first resin layer) located on the side of the first insulating layer 11, a lower layer 30D (second resin layer) located on the side of the second insulating layer 11B, and a middle layer 30M (intermediate resin layer) disposed between the upper layer 30U (first resin layer) and the lower layer 30D (second resin layer) and having a filler content higher than either the upper layer 30U (first resin layer) or the lower layer 30D (second resin layer). The upper layer 30U and the lower layer 30D of the insulating portion 30 do not contain filler, are flexible, and their bonding strength is lower than that between the cathode electrode layer and the second side electrode, enabling them to absorb internal stress and thus suppressing non-connection between the cathode electrode layer and the second side electrode. Furthermore, because the bonding strength of the middle layer 30M is locally high in the insulating portion 30, large-scale damage to the insulating portion 30 can be suppressed, further suppressing non-connection at the connection points in the cathode electrode layer.

[0058] The second side electrode E2 is made of a conductive material. In this example, the second side electrode E2 has a first electrode layer E21, a second electrode layer E22, and a third electrode layer E23, but it can also be a single-layer structure.

[0059] The first electrode layer E21 is made of a material with excellent conductivity. In a preferred example, the thickness of the first electrode layer E21 is 5 μm or more and 15 μm or less, and in a more preferred example, the thickness is 8 μm or more and 12 μm or less. As the first electrode layer E21, it is preferable to use a material with excellent conductivity, i.e., a plating layer containing copper (Cu) or silver (Ag).

[0060] The second electrode layer E22 is an intermediate layer disposed between the first electrode layer E21 and the third electrode layer E23. The second electrode layer E22 prevents the diffusion of Sn and other substances contained in solder, the third electrode layer, etc., and prevents the oxidation of Cu and other substances contained in the first electrode layer. As the material for the second electrode layer E22, Ni and other materials with stronger oxidation resistance than Cu and which hinder metal diffusion can be used. If the second electrode layer E22 is too thin, its oxidation and diffusion prevention effects weaken; if it is too thick, the resistance value increases. A preferred example of the thickness of the second electrode layer E22 is 1 μm to 5 μm, and a more preferred example is 2 μm to 4 μm. When the thickness is above the lower limit, the aforementioned diffusion prevention effect is obtained; when it is below the upper limit, the increase in resistance value can be suppressed. This thickness is 3 μm, for example. Preferably, nickel (Ni), a material more stable than copper (Cu), can be used as the second electrode layer E22.

[0061] The third electrode layer E23 is composed of a conductive material that makes good contact with the Sn alloy (solder) disposed on the outside. Sn alloys known include Sn-Ag-Cu, Sn-Cu, Sn-Sb, or Sb-Bi. The third electrode layer E23 can be composed of a metal with good wettability relative to the solder material (e.g., Sn, SnAg alloys, etc.). A preferred example of the thickness of the third electrode layer E23 is 3 μm or more and 7 μm or less, and a more preferred example is 4 μm or more and 6 μm or less. When the thickness is above the lower limit, the influence of the substrate can be suppressed, and when it is below the upper limit, material costs can be reduced. The third electrode layer E23 can be composed of a material (e.g., Au) containing gold (Au), which has excellent conductivity and good wettability with solder. Furthermore, when using gold, the effect is obtained even if the thickness of the electrode layer is greater than 0 μm and less than 1 μm; when it is greater than 0 μm and less than 0.1 μm, the effect can be obtained while reducing costs.

[0062] Furthermore, the structure and material of the first side electrode E1 can be the same as those of the second side electrode E2. Alternatively, the structure and material of the first side electrode E1 and the second side electrode E2 can also be different.

[0063] The upper cathode electrode layer 14 and the lower cathode electrode layer 14B may each contain at least one conductive material selected from copper, nickel, chromium, and silver. The first side electrode E1 and the second side electrode E2 may each contain at least one conductive material selected from copper, nickel, tin, silver, gold, platinum, palladium, indium, bismuth, and antimony.

[0064] The interface between the anode electrode layer 8 and the upper insulating region 10 or the lower insulating region 10B is not a perfectly flat surface, but has a finely textured surface. The anode electrode layer 8 is not a roughened layer, but is composed of bulk metal. The thickness A1 of the anode electrode layer 8 along the Z-axis direction can be defined by the distance between the upper position ZU of the upper surface (interface) of the anode electrode layer 8 and the lower position ZD of the lower surface (interface). The upper position ZU is the Z-axis position of the plane that fits the point group constituting the upper surface (interface) of the anode electrode layer 8, and can be obtained by the least squares method that minimizes the distance between the point group and the plane. The lower position ZD is the Z-axis position of the plane that fits the point group constituting the lower surface (interface) of the anode electrode layer 8, and can be obtained by the least squares method that minimizes the distance between the point group and the plane. In other words, by setting the average height of the upper concave-convex structure as the upper position ZU and the average height of the lower concave-convex structure as the lower position ZD, the distance between them can be set as the thickness A1 of the anode electrode layer 8.

[0065] The structures above and below the anode electrode layer 8 are substantially symmetrical and identical with respect to the anode electrode layer 8. The thickness of the upper insulating region 10 can be set to M1, and the thickness of the lower insulating region 10B can be set to M2. M1 is defined by the position Z11 of the interface between the upper insulating region 10 and the first insulating layer 11, and the distance between this position and the upper position ZU of the interface between the upper insulating region 10 and the anode electrode layer 8. M2 is defined by the position Z11B of the interface between the lower insulating region 10B and the second insulating layer 11B, and the distance between this position and the lower position ZD of the interface between the lower insulating region 10B and the anode electrode layer 8. In this example, after removing error components, M1 = M2. Furthermore, the thickness of the first insulating layer 11 is set to Z1, and the thickness of the second insulating layer 11B is set to Z2. Z1 is defined by the position Z14 of the interface between the first insulating layer 11 and the upper cathode electrode layer 14, and the distance between this position and Z11. Z2 is defined by the position Z14B of the interface between the second insulating layer 11B and the lower cathode electrode layer 14B, and the distance between the interface Z14B and the position Z11B.

[0066] Furthermore, the thickness M1 of the upper insulating region 10 is substantially equal to the thickness of the upper layer 30U. The thickness M2 of the lower insulating region 10B is substantially equal to the thickness of the lower layer 30D. The thickness A1 of the anode electrode layer 8 is substantially equal to the thickness of the middle layer 30M.

[0067] The anode electrode layer 8, which constitutes the aluminum metal core, is thinner than the roughening layer formed thereon. Therefore, the thickness of the upper layer 30U and the lower layer 30D formed after removing the roughening layer is less than the thickness of the anode electrode layer 8. That is, the thickness M1 (μm) of the upper layer 30U (first resin layer), the thickness M2 (μm) of the lower layer 30D (second resin layer), and the thickness A1 (μm) of the middle layer 30M (intermediate resin layer) can have the following relationship.

[0068] • A1 < M1, A1 < M2

[0069] The thickness Z1 (μm) of the first insulating layer 11 and the thickness Z2 (μm) of the second insulating layer 11B, and the upper layer 30U and the lower layer 30D in the insulating portion 30 can have the following relationship.

[0070] • Z1 < M1, Z2 < M2

[0071] The filler content C in the first insulating layer 11 Z1 (mass%), filler content C in the second insulating layer 11B Z2 (mass%), filler content C in the upper 30U (first resin layer) M1 (mass%), filler content C in the lower 30D (second resin layer) M2 (mass%), and the filler content C in the middle layer 30M (intermediate resin layer) A1 (mass%) can have the following relationship.

[0072] ·C M1 <C A1 C M2 <C A1

[0073] ·C M1 <C Z1 C M2 <C Z2

[0074] With a high filler content and a large thickness, the sealing strength of the connection can be increased. Therefore, under the above-mentioned conditions, the sealing strength of the connection near the cathode electrode layer is relatively high, which can further suppress the non-connection of the connection. In addition, it is believed that with a high filler content, the sealing strength is higher mainly due to surface roughness of the contact area formed during side forming.

[0075] Furthermore, A1, M1, and M2 preferably have the following relationship.

[0076] A1 can be set to 1 (μm) ≤ A ≤ 300 (μm). M1 can be set to 1 (μm) ≤ M1 ≤ 100 (μm). M2 can be set to 1 (μm) ≤ M2 ≤ 100 (μm). The thickness P1 of the protective layer (11, 11B) can be set to 3 (μm) ≤ P1 ≤ 30 (μm). The maximum thickness Cmax of the cathode electrode layer (14, 14B) can be set to 1 (μm) ≤ Cmax ≤ 30 (μm).

[0077] Figure 1 The solid electrolytic capacitor element CE shown is two, but as an example, the number can be increased to four. The number of solid electrolytic capacitor elements CE can be one or more, or several. The thickness of each element in the laminate 100 is the dimension of each element in the lamination direction (Z-axis direction). The thickness d(CE) of each solid electrolytic capacitor element CE can be set to 10 (μm) ≤ d(CE) ≤ 500 (μm).

[0078] The thickness dP(M) of the intermediate layer 20 can be set, for example, to 18 (μm) ≤ dP(M) ≤ 44 (μm). The thickness dP(T) of the topmost layer 20TOP can be set, for example, to 59 (μm) ≤ dP(T) ≤ 264 (μm). The thickness dP(B) of the bottommost layer 20BTM can be set, for example, to 59 (μm) ≤ dP(B) ≤ 264 (μm). Furthermore, the influence of the binding force of the thickness of the insulating layers (20: intermediate layer, topmost layer, bottommost layer) containing resin is much smaller than the influence of the binding force of the glass cloth itself. Therefore, if the binding force effect is considered, the limitation on the thickness of the insulating layer (20) can also be eliminated. However, if a lower limit value of the insulating layer (20) must be set, for example, for the intermediate layer 20, the lower limit value can be set to 15 μm, and the upper limit value can be set to 50 μm.

[0079] The middle layer 20, the top layer 20TOP, and the bottom layer 20BTM can each be made of a prepreg containing thermosetting resins such as epoxy resin and glass cloth. The glass cloth can be a plain woven glass cloth, with the glass fibers (glass filaments, glass strands) constituting the glass cloth extending along the X-axis and Y-axis directions.

[0080] The protective insulator 16 is made of insulating material. Inorganic insulating materials and organic insulating materials are known to be insulating materials.

[0081] As inorganic insulating materials, silicon oxides (e.g., SiO2) and silicon nitrides (e.g., SiN) are known. xMaterials used include aluminum oxides (e.g., Al2O3) and magnesium oxides (e.g., MgO). As organic insulating materials, thermosetting resins such as polyimide and epoxy resin are known. In this example, an epoxy resin containing fillers is used as a suitable insulating material to protect the insulator 16. The protective insulator 16 before thermosetting during manufacturing can be in granular, liquid, particulate, or film form.

[0082] The bottom layer 20BTM can form a support substrate. The structure of the bottom layer 20BTM can be the same as that of the top layer 20TOP, but can be different. The bottom layer 20BTM is made of an insulating material. As insulating materials, the aforementioned inorganic insulating materials and organic insulating materials are known. As insulating material substrates containing inorganic insulating materials, glass substrates and LTCC (low-temperature co-fired ceramic) substrates containing alumina and glass materials are known. As insulating material substrates containing organic insulating materials, glass epoxy boards such as FR4 (Flame Retardant type 4) can also be used, which are made by impregnating epoxy resin in glass fibers (glass cloth or glass nonwoven fabric) and curing them. As an insulating material suitable for the bottom layer 20BTM, a glass epoxy board is used in this example.

[0083] The anode terminal 1, cathode terminal 2, first side electrode E1, and second side electrode E2 are made of metallic materials. An exemplary metallic material is copper (Cu). Materials contained in solder (Sn) may also be included on the surface of the copper layer. These metallic materials may contain other elements.

[0084] The first side electrode E1 may comprise at least one conductive material (metal) selected from copper (Cu), nickel (Ni), tin (Sn), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), indium (In), bismuth (Bi), and antimony (Sb). Specifically, the first side electrode E1 comprises at least one conductive material selected from Cu, Ni, Sn, Ag, Au, Pd, Pt, Cu-Ni, Cu-Sn, Ni-Sn, Sn-Ag, Sn-In, Sn-Bi, Sn-Au, Sn-Sb, Sn-Pd, and pastes of these metallic materials. The first side electrode E1 may be composed of a single layer, or it may be constructed by stacking multiple conductive layers (metal layers) as described above. The materials of the anode terminal 1, the cathode terminal 2, and the second side electrode E2 may be set in the same way as the material of the first side electrode E1.

[0085] Figure 2 The anode electrode layer 8 shown contains a first metal (aluminum). The insulating regions (10, 10B) that serve as the mixing region and the solid electrolyte layers (12, 12B) also contain the first metal (aluminum) as a roughening layer.

[0086] Figure 2 The dielectric layers (9, 9B) shown are, for example, made of aluminum oxide. The thickness of the dielectric layers (9, 9B) is, for example, 1 nm to 1 μm.

[0087] The conductive polymer (compound) contained in the solid electrolyte layer (12, 12B) and its surface conductive polymer layer can include at least one selected from polypyrrole, polyaniline, polythiophene, polyfuran, and their derivatives. Poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (ppy) are preferred as conductive polymers. They can be used alone or in mixtures of two or more. Appropriate dopants can be added to these materials to give them excellent conductivity.

[0088] The conductive layer (13, 13B) is, for example, composed of an adhesive conductive layer (e.g., carbon paste). The adhesive conductive layer contains a conductor and an adhesive. The conductor in the adhesive conductive layer is a carbon-containing material (e.g., graphite) or a metal. The adhesive in the adhesive conductive layer is a resin such as phenolic resin, urea resin, epoxy resin, polyester resin, or polyimide resin, or a hydrocarbon compound such as paraffin oil. The carbon paste is a mixture of graphite powder and an adhesive, and can be used in the conductive layer (13, 13B). Furthermore, the conductive layer (13, 13B) can be formed by a printing method.

[0089] As the metallic conductive layer constituting the cathode electrode layer (14, 14B), copper (Cu), nickel (Ni), silver (Ag), or tin (Sn) can be used, and these metallic conductive layers can be formed by plating. These metallic conductive layers can also be formed by any method such as sputtering. When the plating is formed by electroless plating, the underlying adhesive conductive layer can contain a catalyst metal. The catalyst metal is a noble metal with catalytic activity for electroless plating, and palladium (palladium-based materials), gold, platinum, rhodium, etc., can be used, with palladium being particularly preferred. These can be used alone or in combination of two or more. Alternatively, an additional metal film can be formed on top of a metal film formed by electroless plating or sputtering (thickening).

[0090] Generally, copper plating can be performed using copper sulfate baths, copper pyrophosphate baths, copper cyanide baths, and copper fluoroborate baths. Nickel plating can be performed using Watt's bath (nickel sulfate), aminosulfonic acid bath (nickel aminosulfonate), and full chloride bath (nickel chloride). Tin plating can be performed using sulfuric acid baths and sulfonic acid baths. Various plating methods are known and applicable to the formation of various plating layers.

[0091] The insulating layers (11, 11B) are made of the same first resin (e.g., epoxy resin) and filler as the insulating regions (10, 10B). Furthermore, the filler essentially does not extend into the insulating regions (10, 10B). Therefore, the filler content in the insulating regions (10, 10B) is less than the filler content in the insulating layers (11, 11B).

[0092] The protective layers (15, 15B) are composed of a resin-containing resist material, preferably a material containing both resin and inorganic materials. As the inorganic material, fillers such as silica (silicon oxide) can be used. As the resin material, thermosetting resins such as polyimide or epoxy resin can be used. In this example, a protective layer (15, 15B) with silica added to an epoxy resin is used. The resist material can be a liquid material that melts into a suitable solvent during manufacturing. Furthermore, the protective layers (15, 15B) can be omitted.

[0093] Various methods can be used to form the protective layers (15, 15B). For example, screen printing and gravure printing (transfer printing) can be used. In this example, screen printing is used. The forming processes of the elements on the upper surface and the forming processes of the elements on the lower surface can be performed simultaneously or at different times. If they are performed simultaneously, the manufacturing time can be shortened.

[0094] The insulating portion 30 includes, at least in its upper and lower layers, the constituent material (denoted as material A) contained in the upper insulating region 10 and the lower insulating region 10B. The middle layer 30M of the insulating portion 30 mainly includes the constituent material (denoted as material B) that protects the insulator 16. The resin contained in material A and the resin contained in material B may be the same or different materials.

[0095] Material A is composed of a resin-containing resist material and may include fillers such as silica as needed. As the resin material, thermosetting resins such as polyimide or epoxy resin can be used. As an example of material A, epoxy resin can be used.

[0096] Material B is composed of a resin containing inorganic materials such as silica as filler. As this resin material, thermosetting resins such as epoxy resin can be used. As an example of material B, epoxy resin containing silica as filler can be used. The upper layer 30U and lower layer 30D of the insulating portion 30 contain the epoxy resin contained in materials A and B; as an example, the filler content is low. The middle layer 30M of the insulating portion 30 mainly contains material B, and also contains epoxy resin and filler; as an example, the filler content is higher than that of the upper layer 30U and lower layer 30D. Examples of resins that can be contained in materials A and B include phenolic resin, methacrylic resin, epoxy resin, silicone resin, polycarbonate, polyethylene terephthalate, polyamide, polyimide, polybutadiene, polyethylene, and polystyrene. Furthermore, examples of inorganic materials constituting the filler include silica (SiO2), alumina (Al2O3), and aluminum nitride (AlN).

[0097] Next, the insulating layer (20) that constitutes the top layer 20TOP, the middle layer 20, and the bottom layer 20BTM will be further explained.

[0098] Figure 5 (A) is a diagram showing the planar structure of a glass cloth containing YRN glass fibers. Figure 5 (B) is a diagram showing the longitudinal cross-sectional structure of the insulating layer (20) containing glass cloth. Figure 5 (C) is a cross-sectional view of the filament FIL perpendicular to the long side direction.

[0099] like Figure 5 As shown in (A), the glass cloth contained in the insulating layer (20) has a woven structure with glass filaments YRN extending along the longitudinal direction (Y-axis) and glass filaments YRN extending along the transverse direction (X-axis). The number of glass filaments per unit length (25mm) is set as K (filaments / 25mm). The value of K is, for example, 45 (filaments / 25mm). Each glass filament YRN is a yarn formed by twisting together multiple long filaments FIL. The number of twists per unit length (25mm) is 1 turn for example, but it can also be set to 0.5 turns to 2 turns. In addition, the value of K for the uppermost layer 20TOP is set as K(T), the value of K for the middle layer 20 is set as K(M), and the value of K for the lowermost layer 20BTM is set as K(B). Furthermore, the value of K is the number of the aforementioned glass filaments extending perpendicular to the length direction contained in each 25mm length.

[0100] like Figure 5 As shown in (B), the overall thickness of the insulating layer (20) is set as dP, and the thickness of the glass cloth is set as dG. Within the XZ section of the insulating layer (20), the cross-section of multiple filaments (FIL) extending along the Y-axis can be observed. Within the XZ section of the insulating layer (20), multiple filaments (FIL) extending along the X-axis can be observed.

[0101] The value of dP for the top layer 20TOP is set to dP(T), the value of dP for the middle layer 20 is set to dP(M), and the value of dP for the bottom layer 20BTM is set to dP(B). The relationship of dP values ​​in the example is dP(M) < dP(T), which can be set to dP(M) < dP(B).

[0102] The value of dG for the top layer 20TOP is set to dG(T), the value of dG for the middle layer 20 is set to dG(M), and the value of dG for the bottom layer 20BTM is set to dG(B). The relationship of dG values ​​in the example is dG(M) < dG(T), which can be set to dG(M) < dG(B).

[0103] Let N be the number of bundled filaments (FILs) contained in a single glass fiber (YRN). Let N(T) be the value of N for the top layer (20TOP), N(M) for the middle layer (20), and N(B) for the bottom layer (20BTM). In this example, the relationship between the values ​​of N is N(M) < N(T), which can be set to N(M) < N(G).

[0104] like Figure 5 As shown in (C), the cross-sectional shape of a filament FIL perpendicular to its long side is circular, and its diameter is set to D (μm). The value of D for the topmost layer 20TOP is set to D(T), the value of D for the middle layer 20 is set to D(M), and the value of D for the bottommost layer 20BTM is set to D(B). In the example, the relationship of the values ​​of D is D(M) < D(T), which can be set to D(M) < D(B). Furthermore, when the cross-sectional shape of a filament FIL perpendicular to its long side is deformed from a circle, the diameter of the circle having the area of ​​that cross-section is set to the effective diameter D, and the value of this diameter D is set to the thickness of the filament.

[0105] Evaluation tests were conducted by changing the parameters of the elements constituting the insulating layer (20).

[0106] (Experimental conditions)

[0107] first, Figure 1 The solid electrolytic capacitor shown has two elements CE, but reference... Figure 1For example, the number of solid electrolytic capacitor elements CE is increased to four, and a solid electrolytic capacitor is manufactured by stacking them together. The resin contained in the insulating layer (20) is epoxy resin, and multiple filaments are bundled together to form the glass cloth. Each filament is made of silica glass with SiO2 as the main component. The silica glass used by way of example is E glass (a glass containing 52 (mass%) to 56 (mass%) of SiO2, 12 (mass%) to 16 (mass%) of Al2O3, 20 (mass%) to 25 (mass%) of alkaline earth metal oxides, and 5 (mass%) to 10 (mass%) of B2O3). As the material of the filaments, silica-containing glasses such as NE glass and other known glasses can be used. Even when such glasses are used in glass cloth, the resistance to environmental changes can be enhanced.

[0108] The support substrate, consisting of the bottom 20BTM layer, comprises resin and glass cloth. The resin is epoxy resin. The glass cloth has a plain woven structure composed of multiple glass filaments. Each glass filament contains multiple glass filaments bundled together. The thickness of each glass filament, D(B), is 9 μm, and the number of glass filaments in one glass filament, N(B), is 400. The thickness of the woven structure of the bottom 20BTM layer, dG(B), is 180 μm, and the thickness of the bottom 20BTM layer, dP(B), is 200 μm. The resin content in the bottom 20BTM layer, R(B), is 46% by mass. The number of glass filaments per unit length (25 mm), K (filaments / 25 mm), is K(B) = 59 (filaments / 25 mm). Furthermore, the parameter ranges of the components of the bottom 20BTM layer can be set to the same range as the parameter ranges of the components of the top 20TOP layer, and the same effect can be obtained in this case. The parameters of the components of the bottom 20BTM contribute to environmental resistance, but even if the parameters of the bottom 20BTM components are set to arbitrary values, mechanical strength can be increased by adjusting at least the parameters of the top 20TOP, thus increasing environmental resistance.

[0109] The anode electrode layer 8 in the solid electrolytic capacitor is made of aluminum with a thickness of 25 μm, the dielectric layer (9, 9B) is made of aluminum oxide, and the solid electrolyte layer (12, 12B) is made of a material obtained by impregnating a roughened aluminum layer with a thickness of 50 μm with PEDOT.

[0110] The conductive layer (13, 13B) is made of carbon paste, the cathode electrode layer (14, 14B) is made of copper (Cu) with a thickness of 10 (μm), and the protective layer 15 is made of epoxy resin containing silica filler with a thickness of 20 (μm) (filler content = 40 (mass%)).

[0111] The insulating regions (10, 10B) are made of an epoxy resin material in an aluminum roughening layer with a thickness of 50 (μm). The insulating layers (11, 11B) are epoxy resins with a thickness of 20 (μm) containing silica filler (filler content = 60 (mass %)). The upper and lower layers of the insulating part 30 are epoxy resins with a thickness of 50 (μm) respectively. The middle layer of the insulating part 30 is epoxy resin with a thickness of 25 (μm) containing filler (filler content = 70 (mass %)).

[0112] An aluminum sheet with roughened layers on its upper and lower surfaces is prepared. A photoresist containing epoxy resin and silica filler is printed into a grid pattern to form insulating regions (10, 10B) and insulating layers (11, 11B). PEDOT is impregnated into the grid openings to form solid electrolyte layers (12, 12B). A copper substrate layer is formed on the solid electrolyte layer by sputtering, and copper is plated on the substrate layer to form cathode electrode layers (14, 14B). Then, a protective layer (15) that serves as photoresist is formed on the cathode electrode layer, with a portion of the protective layer opening along the Y-axis, and the cathode electrode layer within the opening is etched.

[0113] Then, a sheet containing the elements of a solid electrolytic capacitor produced through these processes is prepared in four layers, such as... Figure 1 As shown, a sheet is stacked on a support substrate, which serves as the bottom layer, to form a laminate. For this laminated sheet, as... Figure 9 As shown, a groove (GRV) with its depth direction in the negative Z-axis direction is formed by bringing a rotating tool abutting against the laminate. Furthermore, Figure 9 This diagram shows the longitudinal cross-sectional structure of a solid electrolytic capacitor intermediate during tank formation. A rotating blade is inserted into the laminated sheet in the direction of the arrow. After etching the anode electrode layer in this solid electrolytic capacitor intermediate, the tank is filled with epoxy resin containing filler. The laminate is then covered with a protective insulator containing epoxy resin containing filler. If side electrodes and electrode terminals are formed and then individually cut, the solid electrolytic capacitor covered with the protective insulator is completed.

[0114] Solid electrolytic capacitor completed.

[0115] The conditions for the thickness of the insulating layer (20) are set as follows.

[0116] Figure 6 It is a chart showing the parameters of the elements that make up the insulating layer (the top layer).

[0117] In data 1 through data 30, the filament diameter D(T) varies from 4 (μm) to 9 (μm). The number of filament bundles N(T) in a single glass fiber varies from 50 (filaments) to 400 (filaments). The number of glass fibers per unit length in one direction (glass fiber weaving density) K(T) in the glass cloth varies from 45 (filaments / 25mm) to 72 (filaments / 25mm). When the number of longitudinal and transverse filaments differs, the average number of glass fibers in one direction K is given as their average value. The thickness dG(T) of the glass cloth varies from 13 (μm) to 180 (μm). Furthermore, in data 30, two glass cloths with a thickness of 55 (μm) are used, and the total thickness of the glass cloth is set to 110 (μm).

[0118] The resin ratio R(T) (= mass of resin / (mass of resin + mass of glass cloth)) in the insulating layer (20) varies from 46 (mass%) to 100 (mass%). The thickness dP(T) of the uppermost insulating layer (20) varies from 20 (μm) to 240 (μm). In addition, in the values ​​in each table, for example, the thickness dP(T) in data 18, if the values ​​are the same within a certain range, such as 140-180, hyphens are used between the values.

[0119] Figure 7 It is a chart showing the parameters of the elements that make up the insulating layer (intermediate layer).

[0120] In data 1 to data 30, the filament diameter D(M) varies from 4 (μm) to 7.4 (μm). The number of filament bundles N(M) contained in a single glass filament varies from 50 (filaments) to 400 (filaments). The number of glass filaments per unit length in one direction (glass cloth weaving density) K(M) contained in the glass cloth varies from 46 (filaments / 25mm) to 95 (filaments / 25mm). When the number of longitudinal and transverse filaments differs, the average number of glass filaments in one direction is given as their average value. The thickness dG(M) of the glass cloth varies from 13 (μm) to 125 (μm). The resin ratio R(M) contained in the insulating layer (20) (= mass of resin / (mass of resin + mass of glass cloth)) varies from 47 (mass%) to 100 (mass%). The thickness dP(M) of the insulating layer (20) constituting the intermediate layer varies from 20 (μm) to 180 (μm).

[0121] (Evaluation and Results)

[0122] The components of a laminated solid electrolytic capacitor were analyzed. The resin-sealed laminate was cut and separated into individual solid electrolytic capacitors, which were then evaluated. The evaluation criteria included peel resistance, seal performance, and thermal shock resistance.

[0123] (1) Evaluation of peel resistance

[0124] In the peel resistance evaluation, the groove was formed using a 0.3 mm wide cutting blade at a cutting speed of 5 mm / s during the groove formation process. The condition under these conditions was observed and evaluated.

[0125] (Evaluation A): In the peel resistance evaluation, if the insulating layer (20TOP) on the surface of the laminate does not peel off when the groove is formed under the above conditions, it is judged as good (Evaluation A).

[0126] (Evaluation B): In the peel resistance evaluation, if the insulation layer (20TOP) peels off at a cutting speed of 5 mm / s but does not peel off at 1 mm / s when the groove is formed under the above conditions, the product is judged to have reduced quality (Evaluation B).

[0127] (Evaluation C): In the peel resistance evaluation, if the insulation layer (20TOP) peels off 1 to 2 times in 10 attempts even at a cutting speed of 1 mm / s when the groove is formed under the above conditions, the product is judged to have further deteriorated in quality (Evaluation C).

[0128] (Rating D): In the peel resistance evaluation, if the insulation layer (20TOP) peels more than 3 times in 10 attempts when the groove is formed under the above conditions, even at a cutting speed of 1 mm / s, the product is judged as a defective product (Rating D). Figure 10 This is a planar photograph showing the structure around the groove (defective product: rating D (data 13)). Figure 11 This is a planar photograph showing the structure around the groove (Good product: Evaluation A (Data 1)). In the device with Evaluation D, insulating layer peeling areas are formed on both sides of the groove GRV formed by the rotating blade. If the dimensions (DF1, DF2) of these areas in the X-axis direction are 20 μm or more, peeling is considered to have occurred. In the device with Evaluation A, no insulating layer peeling areas are formed.

[0129] (2) Fit evaluation

[0130] (Evaluation A): In the sealing evaluation, in the finished product after stacking and sealing, if all insulation layers (20) are sealed to the solid electrolytic capacitor elements, and the product has absorbed water for more than 168 hours in an environment with a temperature of 30°C and a humidity of 60% (equivalent to JEDEC-MSL3), and after passing through a reflow at a maximum temperature of 260°C, there is no deterioration in product characteristics (characteristic values ​​(electrostatic capacitance, Tanδ (dielectric loss tangent), ESR (equivalent series resistance)) all change by more than 10%), it is judged as a good product (Evaluation A). An LCR tester was used in the evaluation of characteristic values. In (Evaluation A), within the insulation layers (20) between the solid electrolytic capacitor elements, under 500x electron microscopy observation, all insulation layers (20) are sealed to the solid electrolytic capacitor elements, and no voids have been observed.

[0131] (Evaluation B): No characteristic deterioration was found in the reflow after water absorption with an environmental load equivalent to MSL3 (the change in the above characteristic value is less than 10%). However, in the insulation layer (20) between the solid electrolytic capacitor elements, pores were observed in the above microscopic observation. Therefore, the product is judged as (Evaluation B).

[0132] (Evaluation C): If the product exhibits characteristic degradation (i.e., a change of more than 10% in the above characteristic value) during reflow after water absorption with an environmental load equivalent to MSL3, but no characteristic degradation is found after reflow after drying at 120°C for 30 minutes, it is classified as (Evaluation C).

[0133] (Evaluation D): In both the cases of reflow oven treatment after water absorption and the cases of reflow oven treatment after drying, if characteristic deterioration occurred (i.e., a change in the aforementioned characteristic value of 10% or more), the product is classified as (Evaluation D). Furthermore, in the (Evaluation D) product, microscopic observation revealed damage and delamination between layers of the solid electrolytic capacitor element. Damage and delamination were observed not only in the (Evaluation D) product but also in the (Evaluation C) product. Large-scale damage and delamination were observed in (Evaluation D). Delamination was sometimes also observed in the (Evaluation B) product.

[0134] Figure 12 This is a microscope image showing the longitudinal cross-sectional structure of a solid electrolytic capacitor intermediate (not a good product: rating C (data 6)). Figure 13This is a microscopic photograph showing the longitudinal cross-sectional structure of the solid electrolytic capacitor intermediate (Good: Evaluation A (Data 1)). In the device of Evaluation C, the insulating layer (20) is partially peeled off, forming spaces (D201, D202) between the insulating layer (20) and the solid electrolytic capacitor element (CE). Peeling is determined to have occurred when the maximum value of the dimension in the thickness direction (Z-axis direction) of each space (D201, D202) is 2 (μm) or more. In the device of Evaluation A, the aforementioned spaces (D201, D202) are not formed, and no pores are observed.

[0135] (3) Evaluation of thermal shock resistance

[0136] (Evaluation A): In the evaluation of thermal shock resistance, a thermal shock test is conducted for 2000 cycles of temperature change from -55℃ to 125℃. If the changes in the above characteristics are controlled within 10% in the initial stage and after the test, the product is judged as (Evaluation A).

[0137] (Evaluation B): In the evaluation of thermal shock resistance, a thermal shock test is conducted for 2000 cycles of temperature change from -55°C to 125°C. If the above-mentioned characteristic changes are controlled within 10% in the process of up to 1000 cycles, and the changes exceed 10% under the condition of less than 2000 cycles, the product is judged as (Evaluation B).

[0138] (Evaluation C): In the evaluation of thermal shock resistance, if the conditions of (Evaluation B) are not met, and a thermal shock test is repeated for 2000 cycles with a temperature change from -40°C to 105°C, and the changes in the above characteristics are controlled within 10% in the initial stage and after the test in the process of up to 1000 cycles, the product is judged as (Evaluation C).

[0139] (Rating D): In the evaluation of thermal shock resistance, a thermal shock test is conducted that repeats 1000 cycles of temperature change from -40℃ to 105℃. If the above characteristic values ​​change by more than 10% in less than 1000 cycles, the product is judged as (Rating D).

[0140] Figure 8 It is a chart showing the evaluation results of solid electrolytic capacitors when various parameters are used.

[0141] The experimental data for structures with evaluations of (peel resistance, adhesion, and thermal shock resistance) of (A, A, A) are data 1, 2, 3, 4, 17, 18, 19, 20, 21, 22, 26, 28, and 30. Data for structures with evaluations other than (A, A, A) are data 5–16, 23–25, 27, and 29.

[0142] about Figure 6The data for obtaining these ratings (A, A, A) at the top (bottom) level shown must at least meet the following conditions.

[0143] ·5.3(μm)≤D(T)≤9(μm)

[0144] • 200 (items) ≤ N (T) ≤ 408 (items)

[0145] ·55(μm)≤dG(T)≤180(μm)

[0146] • 46 (mass%) ≤ R (T) ≤ 71 (mass%)

[0147] ·65(μm)≤dP(T)≤240(μm)

[0148] Furthermore, the range related to K must at least satisfy the following conditions. When the value of K is within the following range, a result of (A, A, A) can be obtained, but if it is within the range of values ​​for the actual weave structure, it is considered that at least all evaluation items can obtain an effect of evaluation B or C or above.

[0149] • 45 (pieces / 25mm) ≤ K (T) ≤ 60 (pieces / 25mm)

[0150] Here, regarding the value of D(T), it is assumed that even with an error of at least 10%, the strength, constraint force (elastic modulus), and coefficient of linear expansion do not change significantly, and the same effect can be obtained. With this level of error, rounding to the nearest decimal place is possible. Similarly, regarding the values ​​of N(T), dG(T), R(T), and dP(T), it is assumed that the same effect can be obtained even with errors of 10% for each.

[0151] ·5(μm)≤D(T)≤10(μm)

[0152] • 180 (items) ≤ N (T) ≤ 449 (items)

[0153] ·50(μm)≤dG(T)≤198(μm)

[0154] • 41 (mass%) ≤ R (T) ≤ 78 (mass%)

[0155] ·59(μm)≤dP(T)≤264(μm)

[0156] Furthermore, the lower limit of N(T) varies depending on D(T), but from the viewpoint that the strength, constraint force (elastic modulus), and coefficient of linear expansion are defined within the aforementioned parameter ranges, a value of 150 (or higher) is acceptable. Regarding the upper limit, there is no upper limit from the perspective of increased strength, but from the viewpoint of being able to stably produce glass fibers, a value of 500 (or lower) is acceptable, as it is believed that at least all evaluation items will achieve an evaluation of B or C or higher. Regarding the upper limit of dG(T), it is believed that even rounding to the third significant figure will yield the same effect. The preferred range of parameters in this case is as follows.

[0157] ·5(μm)≤D(T)≤10(μm)

[0158] • 150 (items) ≤ N (T) ≤ 500 (items)

[0159] ·50(μm)≤dG(T)≤200(μm)

[0160] • 41 (mass%) ≤ R (T) ≤ 78 (mass%)

[0161] ·59(μm)≤dP(T)≤264(μm)

[0162] Regarding the top (bottom) layer, it is believed that strength, constraint force (elastic modulus), and coefficient of linear expansion affect peel resistance, sealing performance, and thermal shock resistance. It is assumed that the desired effect can be obtained by adjusting N(T) and D(T) respectively. Therefore, with D(T) at 10 μm (upper limit), it is believed that even an N(T) of 100 μm will achieve the desired effect. Furthermore, the constraint force generated by the thickness (dP(T)) of the top (bottom) layer is weaker than that generated by the glass fiber. Therefore, it is believed that even excluding this parameter range (59 (μm) ≤ dP(T) ≤ 264 (μm)), the same effect can be obtained regarding the constraint of element deformation. Therefore, a solid electrolytic capacitor with high environmental resistance can be obtained within the following range.

[0163] ·5(μm)≤D(T)≤10(μm)

[0164] • 100 (items) ≤ N (T) ≤ 500 (items)

[0165] ·50(μm)≤dG(T)≤200(μm)

[0166] • 41 (mass%) ≤ R (T) ≤ 78 (mass%)

[0167] Regarding D(T) and N(T), the following relationship can also be appropriately satisfied. In addition, the value of D(T)×D(T)×N(T) can be calculated from the data, and the next digit of the value can also be rounded.

[0168] 5000 (μm) 2 ·Bar)≤D(T)×D(T)×N(T)≤40000(μm 2 ·strip)

[0169] That is, it is believed that the same effect as described above can be obtained even within the following range.

[0170] 5000 (μm) 2 ·Bar)≤D(T)×D(T)×N(T)≤40000(μm 2 ·strip)

[0171] ·50(μm)≤dG(T)≤200(μm)

[0172] • 41 (mass%) ≤ R (T) ≤ 78 (mass%)

[0173] about Figure 7 The intermediate layer shown provides data that, to obtain these evaluations (A, A, A), must at least meet the following conditions.

[0174] ·4(μm)≤D(M)≤5.3(μm)

[0175] • 50 (items) ≤ N (M) ≤ 100 (items)

[0176] ·13(μm)≤dG(M)≤35(μm)

[0177] • 70 (mass%) ≤ R (M) ≤ 75 (mass%)

[0178] ·20(μm)≤dP(M)≤40(μm)

[0179] Furthermore, the range related to K must at least satisfy the following conditions. It is assumed that when the value of K is within the following range, a result of (A, A, A) can be obtained, but if it is within the range of values ​​of the actual weave structure, then at least all evaluation items can obtain an effect of evaluation B or C or above.

[0180] • 60 (strips / 25mm) ≤ K (M) ≤ 95 (strips / 25mm)

[0181] Here, regarding the value of D(M), it is assumed that the same effect can be obtained even with an error of at least 10%. With this error, rounding to the nearest decimal place is possible. Similarly, regarding the values ​​of N(M), dG(M), R(M), and dP(M), it is assumed that the same effect can be obtained even with errors of 10% each. That is, as follows.

[0182] ·4(μm)≤D(M)≤6(μm)

[0183] • 45 (items) ≤ N (M) ≤ 110 (items)

[0184] ·12(μm)≤dG(M)≤39(μm)

[0185] • 63 (mass%) ≤ R (M) ≤ 83 (mass%)

[0186] ·18(μm)≤dP(M)≤44(μm)

[0187] Furthermore, regarding the upper limit of N(M), if it is smaller than N(T), the effect is significant. However, from the viewpoint that the coefficient of linear expansion is the same as the parameter range mentioned above, if it is below 150 (items), it is considered that at least all evaluation items achieve an effect of B or C or higher. The preferred range of parameters in this case is as follows.

[0188] ·4(μm)≤D(M)≤6(μm)

[0189] • 45 (items) ≤ N (M) ≤ 150 (items)

[0190] ·12(μm)≤dG(M)≤39(μm)

[0191] • 63 (mass%) ≤ R (M) ≤ 83 (mass%)

[0192] ·18(μm)≤dP(M)≤44(μm)

[0193] Regarding the interlayer, it is believed that strength, constraint force (elastic modulus), and coefficient of linear expansion affect peel resistance, sealing performance, and thermal shock resistance. It is assumed that the desired effect can be obtained by adjusting N(M) and D(M) respectively. Therefore, it is believed that even if D(M) is 10 μm (upper limit), the desired effect can still be achieved as long as N(M) is around 100. Furthermore, the constraint force generated by the thickness of the interlayer (dP(M)) is weaker than that generated by the glass fiber. Therefore, it is believed that even excluding this parameter range (18 (μm) ≤ dP(M) ≤ 44 (μm)), the same effect can be obtained regarding the constraint of element deformation. Therefore, a solid electrolytic capacitor with high environmental resistance within the following range is obtained.

[0194] ·4(μm)≤D(M)≤10(μm)

[0195] • 45 (items) ≤ N (M) ≤ 150 (items)

[0196] ·12(μm)≤dG(M)≤39(μm)

[0197] • 63 (mass%) ≤ R (M) ≤ 83 (mass%)

[0198] Regarding D(M) and N(M), the following relationship can also be appropriately satisfied.

[0199] 500 (μm) 2 ·Bar)≤D(M)×D(M)×N(M)≤6500(μm 2 ·strip)

[0200] Furthermore, the value of D(M)×D(M)×N(M) can be calculated from the data, and the last digit of the value can also be rounded. Additionally, in the intermediate layer, N(M) is less than N(T).

[0201] That is, it is believed that the same effect as described above can be obtained even within the following range.

[0202] ·N(M)<N(T)

[0203] 500 (μm) 2 ·Bar)≤D(M)×D(M)×N(M)≤6500(μm 2 ·strip),

[0204] ·12(μm)≤dG(M)≤39(μm),

[0205] • 63 (mass%) ≤ R (M) ≤ 83 (mass%)

[0206] The data for item D are data 13 and data 14, which are devices where the top layer 20TOP does not contain glass cloth. In other words, if the top and bottom insulating layers (20) contain glass cloth, the manufacture of defective products (evaluation D) can be suppressed. Even when the middle layer 20 does not contain glass cloth, it is possible to manufacture devices that do not become defective products (evaluation D), but when it contains glass cloth, it becomes a device with a better evaluation.

[0207] Preferably, the thickness of the glass cloth in the X-axis direction of the intermediate layer 20 is less than the thickness of the glass cloth in the uppermost or lowermost insulating layer (dG(M) < dG(T)), the thickness D(M) of the filaments is also set to be relatively thin to satisfy D(M) < D(T), and the number of filaments N(M) contained in one glass filament is also set to be relatively small to satisfy N(M) < N(T). In this case, the coefficient of linear expansion of the intermediate layer 20 is greater than the coefficient of linear expansion of the uppermost or lowermost insulating layer. Therefore, near the intermediate layer 20, the thermal expansion of the solid electrolytic capacitor elements is easily affected, while on the other hand, the uppermost and lowermost layers, which are located far from the solid electrolytic capacitor elements and can suppress overall thermal expansion, are less prone to thermal expansion, resulting in higher thermal shock resistance.

[0208] Furthermore, even when the above ranges are met, data 6-8 and data 10 also have evaluation items other than evaluation A. Regarding these parameters, it is believed that, as mentioned above, the ranges of D(T), N(T), dG(T), R(T), dP(T), D(M), N(M), dG(M), R(M), and dP(M) can be set based on the values ​​in the charts. The lower limit can also include an error of -10%, and the same effect can be obtained even if the upper limit includes an error of +10%.

[0209] Furthermore, the thickness-related parameters D(T), dG(T), dP(T), D(M), dG(M), and dP(M) were observed using an optical microscope to determine the thickness. When the surfaces of each layer were rough and uneven, the thickness was determined using the average height position obtained from the surface height position using the least squares method. Regarding the parameters R(T) and R(M) related to the resin ratio, after sampling a portion of the object, it was placed in a crucible and fired at 600°C for 1 hour in atmospheric conditions. The weight change of the sample was then measured, and the resin ratio was determined by ash content analysis.

[0210] The parameters of the lowest layer 20BTM constituting the support substrate are not particularly limited, but it is believed that even if it has the same parameters as the highest layer, the same effect can be obtained. Therefore, in this case, at least the following conditions can be met.

[0211] ·5(μm)≤D(B)≤10(μm)

[0212] • 150 (items) ≤ N (B) ≤ 500 (items)

[0213] ·50(μm)≤dG(B)≤200(μm)

[0214] • 41 (mass%) ≤ R (B) ≤ 78 (mass%)

[0215] ·59(μm)≤dP(B)≤264(μm)

[0216] Next, we will briefly explain the manufacturing method of solid electrolytic capacitors.

[0217] First, manufacturing with Figure 2 The solid electrolytic capacitor sheet shown is a laminated structure of element CE. This sheet does not include insulating portions 30; these areas are filled with the same material as the insulating portions (10, 10B). The manufacturing method of the solid electrolytic capacitor sheet includes (a) a metal sheet preparation step, (b) an insulating portion formation step, (c) a solid electrolyte layer formation step, (d) a conductive layer formation step, (e) a cathode electrode layer formation step, (f) a protective layer formation step, and (g) an etching and dividing step of the cathode electrode layer, and these steps are performed sequentially.

[0218] (a) In the metal sheet preparation process, a metal sheet with roughened layers formed on the upper and lower surfaces of the anode electrode layer 8 is prepared. The roughened layers are first formed by roughening both sides of the metal sheet through etching or the like. Next, both sides of the metal sheet are subjected to a formation treatment (oxide film formation treatment and / or anodizing), thereby forming oxide layers on these surfaces. A first dielectric layer (oxide layer: Al2O3 layer in this example) is formed on the upper surface of the anode electrode layer 8, and a second dielectric layer 9B (oxide layer: Al2O3 layer in this example) is formed on the lower surface.

[0219] (b) In the process of forming the insulating regions, a resist (resin + filler) with a grid pattern is coated on the surface of the roughened layer, allowing the resin to penetrate into the interior of the roughened layer, forming insulating regions (10, 10B). The interior of the insulating regions (10, 10B) is not impregnated with filler, but resist containing filler remains on its surface, forming insulating layers (11, 11B). Various methods are known for applying the resist. For example, screen printing, gravure printing, and spraying are known. In this example, screen printing is used. The resist material is material A (e.g., a mixture of epoxy resin and silica filler). As fillers other than silica, alumina and aluminum hydroxide are known.

[0220] (c) In the process of forming the solid electrolyte layer, a conductive polymer is supplied into the openings of the lattice pattern, allowing it to penetrate into the roughened layer to form a solid electrolyte layer (12, 12B). Various methods are known for introducing the conductive polymer. Examples include coating, chemical oxidative polymerization, and electrolytic polymerization.

[0221] (d) In the process of forming the conductive layer, a conductive layer (13, 13B) is formed on top of the solid electrolyte layer (12, 12B). Each conductive layer may be a single layer or two or more layers. As a forming method, a method of coating the conductive layer with a material (e.g., carbon paste) can be used. Screen printing, gravure printing (transfer printing), or a supply method using a dispenser can be used, etc.

[0222] (e) In the process of forming the cathode electrode layer, the cathode electrode layer (14, 14B) is formed on the conductive layer (13, 13B) using a plating method or the like. When forming the cathode electrode layer, firstly, a highly adhesive substrate layer such as copper (Cu) or nickel-chromium alloy (NiCr) is formed by sputtering, and then a plating layer is formed on the substrate layer. In this example, the plating material is copper (Cu).

[0223] (f) In the process of forming the protective layer, a protective film (15, 15B) consisting of a patterned resist is formed on the cathode electrode layer (14, 14B). The protective layer can be formed using screen printing or gravure printing (transfer printing).

[0224] (g) In the etching and segmentation process of the cathode electrode layer, a portion of the cathode electrode layer (14, 14B) is etched using the protective films (15, 15B) as a mask, exposing a portion of the insulating layer (11, 11B), thus segmenting it into multiple rectangular areas. As the etching solution, aqueous solutions of ferric chloride, copper chloride, sulfuric acid, and hydrogen peroxide can be used. Through these processes, solid electrolytic capacitor sheets can be manufactured. Furthermore, the processing steps for elements above the anode electrode layer 8 and the processing steps for elements below the anode electrode layer 8 can be performed simultaneously or separately.

[0225] Next, multiple solid electrolytic capacitor sheets are stacked on a cured glass cloth impregnated with epoxy resin (as...). Figure 1 On the bottommost layer 20BTM of the support substrate shown. An adhesive insulating layer (20) (intermediate layer) as shown is disposed between the sheets, between the sheets and the support substrate, and on the topmost sheet. Furthermore, the topmost layer 20TOP can be laminated and cured by overlapping a specified glass cloth impregnated with epoxy resin (uncured, prepreg material), or it can be laminated and cured after the intermediate layer 20 (uncured glass cloth impregnated with epoxy resin) has been overlapped and cured (glass epoxy board). These sheet assemblies are bonded to manufacture a laminated sheet. A rotating blade is brought into contact with the laminated sheet, as shown... Figure 9As shown, the negative Z-axis direction is set as the depth direction, forming a groove (GRV) along the Y-axis direction. Similarly, a rotating blade is brought into contact with the laminated sheet, and the negative Z-axis direction is set as the depth direction, forming a groove along the X-axis direction. Etching solution is introduced into the formed groove to etch both ends of the anode electrode layer 8, creating a space between the side surface of the anode electrode layer 8 and the initial inner surface of the groove. As the etching solution, an alkaline solution such as sodium hydroxide aqueous solution or an acidic solution such as sulfuric acid can be used. Appropriate additives may also be added to the etching solution as needed.

[0226] The insulating material constituting the protective insulator 16 is filled into the groove, and the insulating material is filled into the space between the side surface of the anode electrode layer 8 and the initial inner surface of the groove to form the insulating part 30. In this filling process, insulating resin is supplied to the upper surface of the laminated sheet, and pressure is applied along the Z-axis to fill the groove and space with insulating resin. The supplied insulating resin can be liquid or solid sheet. As a filling method, compression molding, transfer molding, or injection molding using liquid insulating resin can be used. As a filling method, a method of attaching sheet-like resin sealant to the surface of the laminated sheet and stamping the resin sealant to flatten it can also be used.

[0227] Next, a rotating blade is brought into contact with the laminated sheet, and a groove is formed along the Y-axis with the positive Z-axis as the depth direction, exposing one side for forming the first side electrode E1 and the other side for forming the second side electrode E2. Then, the first side electrode E1 and the second side electrode E2 are formed on the inner surface of the groove using a plating method or the like. Furthermore, the groove is formed at a position where the first side electrode E1 can contact one side of the anode electrode layer 8, and the second side electrode E2 can contact the other side of the cathode electrode layers (14, 14B). Finally, the rotating blade is brought into contact with the laminated sheet, and a grid-like cut is performed to cut out individual solid electrolytic capacitors. Furthermore, the anode terminal 1 and the cathode terminal 2 can be formed by patterning the electrode material on the bottom layer during the process up to the formation of the side electrodes after the solid electrolytic capacitor elements are laminated to form a laminate.

[0228] As described above, the solid electrolytic capacitor of the first embodiment includes: a laminate comprising a plurality of stacked solid electrolytic capacitor elements; a first layer fixed to a first surface of the laminate; and a second layer fixed to a second surface of the laminate, the first layer comprising a first resin and a first glass cloth, and the second layer comprising a second resin and a second glass cloth.

[0229] In the solid electrolytic capacitor of the first method, at least the first glass cloth has a flat-woven structure composed of a plurality of glass filaments, and a plurality of glass filaments are bundled in one of the glass filaments. The thickness D(T) of one of the glass filaments, the number N(T) of the glass filaments contained in one of the glass filaments, the thickness dG(T) of the braided structure, the ratio R(T) of the resin contained in the first layer, and the thickness dP(T) of the first layer satisfy the following relationships: 5 (μm) ≤ D(T) ≤ 10 (μm), 100 (filaments) ≤ N(T) ≤ 500 (filaments), 50 (μm) ≤ dG(T) ≤ 200 (μm), 41 (mass%) ≤ R(T) ≤ 78 (mass%).

[0230] The third type of solid electrolytic capacitor also includes an intermediate layer disposed between two adjacent solid electrolytic capacitor elements in the thickness direction, the intermediate layer comprising a third resin and a third glass cloth.

[0231] In the solid electrolytic capacitor of the fourth type, the third glass cloth has a flat woven structure composed of multiple glass filaments. In the third glass cloth, a glass filament contains multiple glass filaments. The thickness D(M) of a glass filament, the number N(M) of glass filaments contained in a glass filament, and the thickness dG(M) of the woven structure satisfy the following relationship: dG(M) < dG(T), D(M) < D(T), N(M) < N(T).

[0232] In the fifth type of solid electrolytic capacitor, the ratios of D(M), N(M), dG(M), and resin contained in the intermediate layer R(M) satisfy the following relationships: 4 (μm) ≤ D(M) ≤ 6 (μm), 10 (strips) ≤ N(M) ≤ 150 (strips), 12 (μm) ≤ dG(M) ≤ 39 (μm), and 63 (mass%) ≤ R(M) ≤ 83 (mass%).

[0233] In the solid electrolytic capacitor of the sixth type, the ratios of D(M), N(M), dG(M), and the resin contained in the aforementioned intermediate layer, R(M), satisfy the following relationship: 500 (μm 2 ·Bar)≤D(M)×D(M)×N(M)≤6500(μm 2 • 12 (μm) ≤ dG (M) ≤ 39 (μm), 63 (mass%) ≤ R (M) ≤ 83 (mass%).

[0234] In the seventh type of solid electrolytic capacitor, D(T) and N(T) satisfy the following relationship: 5000 (μm 2 ·Bar)≤D(T)×D(T)×N(T)≤40000(μm 2 ·strip).

[0235] Furthermore, within the range of various parameters, within the range of any parameter P, P min ≤P≤P max Given the given information, it can also be set as (P) min +ΔP)≤P≤(P max -ΔP), ΔP = (P max -P min The error range can be set as P × 95% ≤ P ≤ P × 105%, or R = 20, R = 30, or R = 40. Additionally, when the parameter P is a specific numerical value, its error range can be set as P × 95% ≤ P ≤ P × 105%.

[0236] The above descriptions have illustrated various embodiments, but are not limited to these embodiments. Various omissions, substitutions, and modifications are possible. Furthermore, elements from different embodiments can be combined to form other embodiments. Additionally, as can be understood from the above description, the various embodiments described herein can be modified without departing from the scope and spirit of this disclosure. Therefore, the various embodiments disclosed herein are not intended to be limiting; the true scope and spirit are defined by the claims.

Claims

1. A solid electrolytic capacitor, wherein, have: A laminate, which comprises multiple solid electrolytic capacitor elements stacked together; The first layer, which is fixed to the first surface of the laminate; and The second layer is fixed to the second surface of the laminate. The first layer comprises a first resin and a first glass cloth. The second layer comprises a second resin and a second glass cloth.

2. The solid electrolytic capacitor according to claim 1, wherein, At least the first glass cloth has a flat-woven structure composed of multiple glass filaments. A single glass filament may contain multiple long glass filaments. The thickness D(T) of one glass filament, the number N(T) of one glass filament, the thickness dG(T) of the braided structure, and the ratio R(T) of the resin contained in the first layer satisfy the following relationship: 5≤D(T)≤10 100≤N(T)≤500 50≤dG(T)≤200、 41≤R(T)≤78, The unit of D(T) is μm; the unit of N(T) is stripe; the unit of dG(T) is μm; the unit of R(T) is mass.

3. The solid electrolytic capacitor according to claim 1, wherein, It also includes: an intermediate layer disposed between two adjacent solid electrolytic capacitor elements in the thickness direction. The intermediate layer comprises a third resin and a third glass cloth.

4. The solid electrolytic capacitor according to claim 3, wherein, The third glass cloth has a flat-woven structure composed of multiple glass filaments. In the third glass cloth, A single glass filament may contain multiple long glass filaments. The thickness D(M) of one glass filament, the number N(M) of glass filaments contained in one glass filament, and the thickness dG(M) of the braided structure satisfy the following relationship: dG(M) < dG(T) D(M) < D(T), N(M) < N(T).

5. The solid electrolytic capacitor according to claim 4, wherein, The ratios of D(M), N(M), dG(M), and the resin contained in the intermediate layer, R(M), satisfy the following relationship: 4≤D(M)≤10 45≤N(M)≤150 12≤dG(M)≤39、 63≤R(M)≤83, The unit of D(M) is μm; the unit of N(M) is stripe; the unit of dG(M) is μm; the unit of R(M) is mass.

6. The solid electrolytic capacitor according to claim 4, wherein, The ratios of D(M), N(M), dG(M), and the resin contained in the intermediate layer, R(M), satisfy the following relationship: 500≤D(M)×D(M)×N(M)≤6500, 12≤dG(M)≤39、 63≤R(M)≤83, The unit of D(M)×D(M)×N(M) is μm. 2 • dG(M) is in μm; R(M) is in mass%.

7. The solid electrolytic capacitor according to claim 2, wherein, D(T) and N(T) satisfy the following relationship: 5000≤D(T)×D(T)×N(T)≤40000, The unit of D(T)×D(T)×N(T) is μm. 2 ·strip.

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