Solid electrolytic capacitor

Abstract

A solid electrolytic capacitor having high resistance to environmental changes is expected. This solid electrolytic capacitor comprises: a laminate 100 including a plurality of laminated 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 contains a first resin and a first glass cloth. The lowermost layer 20BTM contains a second resin and a second glass cloth.

Description

Solid electrolytic capacitors

[0001] This disclosure relates to solid electrolytic capacitors.

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

[0003] International Publication No. 2019 / 087692

[0004] Solid electrolytic capacitors, which have high resistance to environmental changes, are expected to be a promising technology.

[0005] The solid electrolytic capacitor of this disclosure comprises a laminate including 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, wherein the first layer includes a first resin and a first glass cloth, and the second layer includes a second resin and a second glass cloth.

[0006] The solid electrolytic capacitors of this disclosure offer increased resistance to environmental changes.

[0007] Figure 1 shows the longitudinal cross-sectional configuration of a solid electrolytic capacitor. Figure 2 shows the longitudinal cross-sectional configuration of a solid electrolytic capacitor element. Figure 3 is a diagram illustrating the layer structure of a solid electrolytic capacitor. Figure 4 is an enlarged view of the region near the second side electrode in a solid electrolytic capacitor element. Figure 5(A) shows the planar configuration of a glass cloth containing glass yarn YRN, Figure 5(B) shows the longitudinal cross-sectional configuration of an insulating layer (20) containing glass cloth, and Figure 5(C) is a cross-sectional view perpendicular to the longitudinal direction of the filament FIL. Figure 6 is a diagram showing the parameters of the elements constituting the insulating layer (uppermost layer). Figure 7 is a diagram showing the parameters of the elements constituting the insulating layer (intermediate layer). Figure 8 is a diagram showing the evaluation results of a solid electrolytic capacitor using each parameter. Figure 9 shows the longitudinal cross-sectional configuration of a solid electrolytic capacitor intermediate during groove formation. Figure 10 is a planar photograph of the groove surrounding structure (defective product). Figure 11 is a planar photograph of the groove surrounding structure (good product). Figure 12 is a micrograph of the longitudinal cross-sectional structure of a defective solid electrolytic capacitor intermediate. Figure 13 is a micrograph of the longitudinal cross-sectional structure of a good solid electrolytic capacitor intermediate.

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals, and redundant explanations will be omitted.

[0009] Figure 1 shows the longitudinal cross-sectional configuration of a solid electrolytic capacitor.

[0010] The solid electrolytic capacitor comprises a bottom layer 20BTM as a support substrate, a laminate 100 including the support substrate, and protective insulators 16 provided on the top surface and sides of the laminate 100 where electrodes are not formed. An anode terminal 1 and a cathode terminal 2 are provided on the lower surface of the support substrate. A first side electrode E1 electrically connected to the anode terminal 1 is provided on the first side surface S1 of the laminate 100. A second side electrode E2 electrically connected to the cathode terminal 2 is provided on the second side surface S2 of the laminate 100.

[0011] A three-dimensional Cartesian coordinate system is established. The stacking direction of the solid electrolytic capacitor elements CE in the laminate 100 is defined as the Z-axis direction. The X-axis is perpendicular to the Z-axis and extends in the direction from the first side electrode E1 to the second side electrode E2. The Y-axis is perpendicular to both the Z-axis and the X-axis. The first side surface S1 is one YZ plane of the laminate 100, and the second side surface S2 is the other YZ plane of the laminate 100.

[0012] The laminate 100 comprises a plurality of solid electrolytic capacitor elements CE and a plurality of insulating layers (20). The plurality of insulating layers (20) comprises a bottom layer 20BTM (20), an uppermost layer 20TOP (20), and one or more intermediate layers 20.

[0013] The bottom layer 20BTM (20) constitutes a support substrate. The top layer 20TOP is positioned between the protective insulator 16 and the upper solid electrolytic capacitor element CE. The multiple intermediate layers 20 include an intermediate layer 20 positioned between the bottom layer 20BTM and the lower solid electrolytic capacitor element, an intermediate layer 20 positioned between adjacent solid electrolytic capacitor elements CE in the thickness direction, and an intermediate layer 20 positioned between the top layer 20TOP and the upper solid electrolytic capacitor element CE.

[0014] The bottom layer 20BTM increases the mechanical strength of the solid electrolytic capacitor and also functions as a barrier to protect the internal layers from external contaminants. The top layer 20TOP increases the mechanical strength of the solid electrolytic capacitor and, together with the protective insulator 16, also functions as a barrier to protect the internal layers from external contaminants. By having a bottom layer 20BTM and an top layer 20TOP, the solid electrolytic capacitor can suppress stress generated inside the laminate in response to environmental changes. Furthermore, by having one or more intermediate layers 20, the solid electrolytic capacitor can further suppress stress generated inside the laminate in response to environmental changes.

[0015] The figure shows two solid electrolytic capacitor elements CE (first solid electrolytic capacitor element CE1 and second solid electrolytic capacitor element CE2). The number of solid electrolytic capacitor elements CE can be two or more, for example, four or five. Even when the number of solid electrolytic capacitor elements CE is increased, an intermediate layer 20 is placed between adjacent solid electrolytic capacitor elements CE in the thickness direction.

[0016] Figure 2 shows the longitudinal cross-sectional configuration of a solid electrolytic capacitor element CE.

[0017] One solid electrolytic capacitor element CE is equipped with an anode electrode layer 8.

[0018] The solid electrolytic capacitor element CE includes, in the upper region of the anode electrode layer 8, 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 (the first cathode electrode layer). The solid electrolyte layer 12 is composed of a roughened layer containing a conductive polymer. In the vicinity of the interface between the anode electrode layer 8 and the solid electrolyte layer 12, a dielectric layer 9 is formed along the concavo-convex 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 inside the roughened layer during the addition to the roughened layer may 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 surfaces 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. An 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 upper surface of the upper cathode electrode layer 14.

[0019] In the upper region of the anode electrode layer 8, in the vicinity of both ends in the X-axis direction, an upper insulating region 10 is formed as a pair of mixed regions. One upper insulating region 10 is located in the vicinity of the first side electrode E1. The other upper insulating region 10 is located in the vicinity of 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 contains a first metal and a first resin. The first metal is aluminum that constitutes the roughened layer, and the first resin is a thermosetting resin such as an epoxy resin.

[0020] The solid electrolytic capacitor element CE comprises 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 a conductive polymer. 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 of 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 to it may 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 12, but also on the lower second surface 11SB of a pair of second insulating layers 11B formed at both ends of the solid electrolytic capacitor element CE in the X-axis direction. A lower cathode electrode layer 14B is formed on the lower surface of the second conductive layer 13B. A second protective layer 15B is formed on the lower surface of the lower cathode electrode layer 14B.

[0021] In the lower region of the anode electrode layer 8, a pair of lower insulating regions 10B are formed as mixed regions 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 first metal (a roughened layer made of aluminum) and the first resin (a thermosetting resin such as epoxy resin).

[0022] 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 interposed between the second side electrode E2 and the anode electrode layer 8.

[0023] The material of the insulating portion 30 includes the same material as that of the protective insulator 16, and preferably includes a filler in a resin (e.g., epoxy resin). The insulating portion 30 has a three-layer structure of an upper layer 30U, a middle layer 30M, and a lower layer 30D. The insulating portion 30 may have a single-layer structure.

[0024] An example of the material of the anode electrode layer 8 is aluminum. An example of the material of the roughened layer formed on the upper and lower surfaces of the anode electrode layer 8 is aluminum. An example of the material of the dielectric layer 9 formed near the surface of the anode electrode layer 8 is aluminum oxide (Al ２ O ３ ). An example of the material of the solid electrolyte layer 12 is obtained by introducing a conductive polymer into a roughened layer of aluminum. An example of the material of the upper cathode electrode layer 14 is copper. The materials of the elements below the anode electrode layer 8 are the same as those of the corresponding upper elements.

[0025] The mixed regions (insulating regions (10, 10B)) on the first side electrode side and the second side electrode side include a first metal (such as aluminum) and a first resin (a thermosetting resin such as epoxy resin). The insulating layers (11, 11B) on the first side electrode side and the second side electrode side include a filler such as silica and a resin (a thermosetting resin such as epoxy resin).

[0026] 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 in contact with and electrically connected to the upper cathode electrode layer 14 and the lower cathode electrode layer 14B, but the mechanical resistance of this connection portion depends on the stress generated in the vicinity of the second side electrode E2.

[0027] FIG. 3 is a diagram for explaining the layer structure of the solid electrolytic capacitor.

[0028] In the layer structure on the anode connection side, the layers are arranged from top to bottom between the protective insulator 16 and the lower solid electrolytic capacitor element CE as follows: top layer 20TOP, intermediate layer 20, first protective layer 15, upper cathode electrode layer 14, first insulating layer 11, upper insulating region 10, anode electrode layer 8, lower insulating region 10B, second insulating layer 11B, lower cathode electrode layer 14B, second protective layer 15B, and intermediate layer 20. The intermediate layer 20, which contains only resin, flows from the upper intermediate layer 20 and is arranged adjacent to the anode connection side of the first protective layer 15 and the upper cathode electrode layer 14. Similarly, the intermediate layer 20, which contains only resin, flows from the lower intermediate layer 20 and is arranged adjacent to the anode connection side of the second protective layer 15B and the lower cathode electrode layer 14B. The lower part of the lower solid electrolytic capacitor element CE has the intermediate layer 20 and the bottom layer 20BTM.

[0029] In the central layer structure located between the anode connection side and the cathode connection side, the layers between the protective insulator 16 and the lower solid electrolytic capacitor element CE are arranged in the following order from top to bottom: the top layer 20TOP, the intermediate layer 20, the first protective layer 15, the upper cathode electrode layer 14, the first conductive layer 13, the first solid electrolyte layer 12, the first dielectric layer 9, the anode electrode layer 8, the second dielectric layer 9B, the second solid electrolyte layer 12B, the second conductive layer 13B, the lower cathode electrode layer 14B, the second protective layer 15B, and the intermediate layer 20. The lower part of the lower solid electrolytic capacitor element CE has the intermediate layer 20 and the bottom layer 20BTM.

[0030] In the layer structure on the cathode connection side, the uppermost layer 20TOP, intermediate layer 20, first protective layer 15, upper cathode electrode layer 14, first insulating layer 11, upper insulating region 10, anode electrode layer 8, lower insulating region 10B, second insulating layer 11B, lower cathode electrode layer 14B, second protective layer 15B, and intermediate layer 20 are arranged from top to bottom between the protective insulator 16 and the lower solid electrolytic capacitor element CE. An insulating portion 30 containing resin and filler is arranged adjacent to the cathode connection side of the upper insulating region 10 and the anode electrode layer 8. The lower part of the lower solid electrolytic capacitor element CE has the intermediate layer 20 and the bottommost layer 20BTM arranged therein.

[0031] Next, we will further explain the layer structure, materials, and dimensions of the cathode connection side.

[0032] Figure 4 is an enlarged view of the region near the second side electrode in a solid electrolytic capacitor element.

[0033] The insulating portion 30 is interposed between the second side surface 82 and the second side electrode E2 of the anode electrode layer 8. The insulating portion 30 contains resin and may further contain filler. The second side surface 82 protrudes toward the second side electrode E2, and within the XZ cross-section, the tip portion constituting the second side surface 82 is pointed so as to have two sides that form an acute angle. The laminated structure along the Z axis passing through the insulating portion 30 comprises, from top to bottom, the upper cathode electrode layer 14, the first insulating layer 11, the insulating portion 30, the second insulating layer 11B, and the lower cathode electrode layer 14B.

[0034] A first insulating layer 11 is positioned directly beneath the upper cathode electrode layer 14. In other words, the first insulating layer 11 is interposed between the upper cathode electrode layer 14 and the insulating portion 30. A second insulating layer 11B is positioned directly above the lower cathode electrode layer 14B. In other words, the second insulating layer 11B is interposed between the lower cathode electrode layer 14B and the insulating portion 30. In this example of a solid electrolytic capacitor, the adhesive strength between the upper cathode electrode layer 14 and the lower cathode electrode layer 14B and the second side electrode E2 is increased, while the adhesive strength of areas other than these adhesive areas is relatively reduced.

[0035] When environmental changes such as temperature fluctuations occur, and stress is generated internally, the areas with relatively low adhesive strength will delaminate due to the internal stress, while the connection portion of the cathode electrode layer can be spared from the effects of the internal stress. Therefore, solid electrolytic capacitors having this structure have increased resistance to environmental changes.

[0036] In the solid electrolytic capacitor of this example, a prepreg made of a mixture of resin and glass cloth can be used for the insulating layers constituting the intermediate layer 20, the uppermost layer 20TOP, and the bottommost layer 20BTM in the laminate shown in Figure 1. In the solid electrolytic capacitor of this example, the use of a prepreg increases resistance to environmental changes.

[0037] The first insulating layer 11 and the second insulating layer 11B, which are positioned near the cathode electrode layer, each contain a resin and a filler, respectively, to enhance the adhesion strength near the cathode electrode layer.

[0038] The insulating portion 30 comprises 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 an intermediate layer 30M (intermediate resin layer) interposed between the upper layer 30U (first resin layer) and the lower layer 30D (second resin layer), having a higher filler content than either the upper layer 30U (first resin layer) or the lower layer 30D (second resin layer). The upper layer 30U and lower layer 30D of the insulating portion 30 do not contain fillers, are soft, and have a lower adhesion strength than the adhesion strength between the cathode electrode layer and the second side electrode, thus absorbing internal stress and suppressing disconnection between the cathode electrode layer and the second side electrode. Furthermore, because the adhesion strength of the intermediate layer 30M is partially high in the insulating portion 30, large-scale damage to the insulating portion 30 can be suppressed, and disconnection of the connection portion in the cathode electrode layer can be further suppressed.

[0039] The second side electrode E2 is made of a conductive material. In this example, the second side electrode E2 comprises a first electrode layer E21, a second electrode layer E22, and a third electrode layer E23, but it may also be a single-layer structure.

[0040] The first electrode layer E21 is made of a material with excellent electrical conductivity. A preferred example of the thickness of the first electrode layer E21 is 5 μm to 15 μm, and a more preferred example is a thickness of 8 μm to 12 μm. Preferably, the first electrode layer E21 can be a plating layer containing a material with excellent conductivity, i.e., copper (Cu) or silver (Ag).

[0041] The second electrode layer E22 is an intermediate layer interposed between the first electrode layer E21 and the third electrode layer E23. The second electrode layer E22 has the role of preventing the diffusion of Sn and other metals contained in the solder and the third electrode layer, and preventing the oxidation of Cu and other metals contained in the first electrode layer. As the material of the second electrode layer E22, nickel (Ni), which is more resistant to oxidation than Cu and inhibits metal diffusion, can be used. If the second electrode layer E22 is too thin, its oxidation and diffusion prevention effect will be weakened, and if it is too thick, the resistance will increase. A preferred example thickness of the second electrode layer E22 is 1 μm to 5 μm, and a more preferred example thickness is 2 μm to 4 μm. When the thickness is above the lower limit, the above diffusion prevention effect can be obtained, and when it is below the upper limit, the increase in the resistance can be suppressed. Exemplarily, this thickness is 3 μm. Preferably, nickel (Ni), which is a more stable material than copper (Cu), can be used as the second electrode layer E22.

[0042] The third electrode layer E23 is made of a conductive material that makes good contact with the externally provided Sn alloy (solder). Known Sn alloys include Sn-Ag-Cu, Sn-Cu, Sn-Sb, or Sb-Bi. The third electrode layer E23 can be made of a metal with good wettability to the solder material (for example, an alloy of Sn or SnAg). A preferred example of the thickness of the third electrode layer E23 is 3 μm to 7 μm, and a more preferred example is 4 μm to 6 μm. 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 may also be made of a material containing gold (Au) (e.g., Au) which has excellent conductivity and good wettability with solder. Furthermore, when using gold, the electrode layer thickness can be greater than 0 μm but less than or equal to 1 μm to be effective, and if it is greater than 0 μm but less than or equal to 0.1 μm, the effect can be obtained while reducing costs.

[0043] The structure and material of the first side electrode E1 may be the same as that of the second side electrode E2. However, the structure and material of the first side electrode E1 and the second side electrode E2 may be different.

[0044] The upper cathode electrode layer 14 and the lower cathode electrode layer 14B may each contain at least one conductive material selected from the group consisting of 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 the group consisting of copper, nickel, tin, silver, gold, platinum, palladium, indium, bismuth, and antimony.

[0045] 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 fine uneven structure. The anode electrode layer 8 is made of bulk metal, not a roughened layer. The thickness A1 of the anode electrode layer 8 along the Z-axis 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 a plane that fits the point cloud constituting the upper surface (interface) of the anode electrode layer 8, and can be determined by the least squares method that minimizes the distance between the point cloud and the plane. The lower position ZD is the Z-axis position of a plane that fits the point cloud constituting the lower surface (interface) of the anode electrode layer 8, and can be determined by the least squares method that minimizes the distance between the point cloud and the plane. In other words, the average height position of the upper uneven structure can be defined as the upper position ZU, the average height position of the lower uneven structure as the lower position ZD, and the distance between these two positions as the thickness A1 of the anode electrode layer 8.

[0046] The structure above and below the anode electrode layer 8 is basically identical and symmetrical with respect to the anode electrode layer 8. The thickness of the upper insulating region 10 can be M1, and the thickness of the lower insulating region 10B can be M2. M1 is defined by the distance between the interface position Z11 between the upper insulating region 10 and the first insulating layer 11 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 distance between the interface position Z11B between the lower insulating region 10B and the second insulating layer 11B and the lower position ZD of the interface between the lower insulating region 10B and the anode electrode layer 8. In this example, excluding error components, M1 = M2 is satisfied. Also, the thickness of the first insulating layer 11 is Z1, and the thickness of the second insulating layer 11B is Z2. Z1 is defined by the distance between the interface position Z14 and position Z11 between the first insulating layer 11 and the upper cathode electrode layer 14. Z2 is defined by the distance between the interface position Z14B between the second insulating layer 11B and the lower cathode electrode layer 14B and position Z11B.

[0047] The thickness M1 of the upper insulating region 10 is basically equal to the thickness of the upper layer 30U. The thickness M2 of the lower insulating region 10B is basically equal to the thickness of the lower layer 30D. The thickness A1 of the anode electrode layer 8 is basically equal to the thickness of the middle layer 30M.

[0048] Since the anode electrode layer 8, which constitutes the aluminum metal core, is thinner than the roughened layer formed on top of it, the thicknesses of the upper layer 30U and lower layer 30D formed by removing the roughened layer are smaller 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 relationships: A1 < M1, A1 < M2

[0049] 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 lower layer 30D of the insulating portion 30 can have the following relationship: Z1 < M1, Z2 < M2

[0050] 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 layer 30U (first resin layer) Ｍ１ (mass%), filler content C in the lower layer 30D (second resin layer) Ｍ２ (mass%), and filler content C in the middle layer 30M (intermediate resin layer) Ａ１ (mass%) can have the following relationship.

[0051] ・C Ｍ１ < C Ａ１ , C Ｍ２ < C Ａ１ ・C Ｍ１ < C Ｚ１、 C Ｍ２ < C Ｚ２

[0052] When the filler content is high and the thickness is large, the adhesion strength at the connection site can be increased. Therefore, when having the above relationship, relatively, the adhesion strength of the connection site near the cathode electrode layer becomes high, and the non-connection of the connection site can be further suppressed. When the filler content is high, it is considered that the adhesion strength becomes high due to factors such as the surface at the contact site becoming rough during the side surface forming process.

[0053] In addition, it is preferable that A1, M1, and M2 have the following relationship.

[0054] 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 value Cmax of the thickness of the cathode electrode layer (14, 14B) can be set to 1 (μm) ≤ Cmax ≤ 30 (μm).

[0055] The number of solid electrolytic capacitor elements CE shown in Figure 1 is two, but as an example, this number may be increased to four. The number of solid electrolytic capacitor elements CE can be one or more, and there may be any number. 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).

[0056] 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 top layer 20 TOP can be set, for example, to 59 (μm) ≤ dP(T) ≤ 264 (μm). The thickness dP(B) of the bottom layer 20 BTM can be set, for example, to 59 (μm) ≤ dP(B) ≤ 264 (μm). Note that the influence of the constraint force on the thickness of the insulating layer (20: intermediate layer, top layer, bottom layer) containing resin is considerably smaller than the influence of the constraint force of the glass cloth itself, so if we focus on the constraint force effect, we can remove the limit on the thickness of the insulating layer (20). However, if we were to deliberately set a lower limit for the insulating layer (20), for example, the lower limit for the intermediate layer 20 could be 15 μm and the upper limit could be 50 μm.

[0057] The intermediate layer 20, the uppermost layer 20TOP, and the bottommost layer 20BTM each contain a thermosetting resin such as epoxy resin and can be prepregs further containing glass cloth. The glass cloth can be a plain weave glass cloth, and the glass fibers (glass yarn, glass filament) constituting the glass cloth extend along the X-axis and Y-axis directions.

[0058] The protective insulator 16 is made of an insulating material. Inorganic insulating materials and organic insulating materials are known as insulating materials.

[0059] As an inorganic insulating material, silicon oxide (e.g., SiO ２ ), silicon nitride (e.g., SiN ｘ ), aluminum oxide (e.g., Al ２ O ３Examples include magnesium oxide (e.g., MgO). As organic insulating materials, thermosetting resins such as polyimide and epoxy resins are known. In this example, an epoxy resin containing a filler is used as a suitable insulating material for the protective insulator 16. The form of the protective insulator 16 before thermosetting during manufacturing can be granular, liquid, granular, or film-like.

[0060] The bottom layer 20BTM can constitute a support substrate. The structure of the bottom layer 20BTM may be the same as that of the top layer 20TOP, but it can also be a different structure. The bottom layer 20BTM is made of an insulating material. As insulating materials, the inorganic insulating materials and organic insulating materials mentioned above are known. As insulating material substrates containing inorganic insulating materials, glass substrates and LTCC (Low Temperature Co-firing Ceramics) substrates containing alumina and glass materials are known. As insulating material substrates containing organic insulating materials, glass epoxy substrates such as FR4 (Flame Retardant type 4), which are made by impregnating glass fibers (glass cloth or glass nonwoven fabric) with epoxy resin and curing them, can also be used. In this example, a glass epoxy substrate is used as a suitable insulating material for the bottom layer 20BTM.

[0061] The anode terminal 1, cathode terminal 2, first side electrode E1, and second side electrode E2 are made of a metallic material. An exemplary metallic material is copper (Cu). The copper layer may contain solder-containing material (Sn) on its surface. These metallic materials may contain other elements.

[0062] The first side electrode E1 may include at least one conductive material (metal) selected from the group consisting of copper (Cu), nickel (Ni), tin (Sn), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), indium (In), bismuth (Bi), and antimony (Sb). More specifically, the first side electrode E1 includes at least one conductive material selected from the group consisting of 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 consist of a single layer, or it may be constructed by laminating multiple conductive layers (metal layers) as described above. The materials for the anode terminal 1, cathode terminal 2, and second side electrode E2 can each be set in the same way as the material for the first side electrode E1.

[0063] The anode electrode layer 8 shown in Figure 2 contains a first metal (aluminum). The insulating region (10, 10B) and the solid electrolyte layer (12, 12B), which are mixed regions, also contain a first metal (aluminum) as a roughened layer.

[0064] The dielectric layer (9,9B) shown in Figure 2 is, exemplified, made of aluminum oxide. The thickness of the dielectric layer (9,9B) is, for example, 1 nm to 1 μm.

[0065] The conductive polymer (compound) contained in the solid electrolyte layer (12, 12B) and the conductive polymer layer on its surface may include at least one selected from the group consisting of polypyrrole, polyaniline, polythiophene, polyfuran, and derivatives thereof. Poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (ppy) are preferably used as conductive polymers. These may be used individually or in combination of two or more. These materials can be given excellent conductivity by adding appropriate dopants.

[0066] The conductive layer (13, 13B) consists of, for example, an adhesive conductive layer (e.g., carbon paste). The adhesive conductive layer includes a conductor and an adhesive. The conductor of the adhesive conductive layer is a carbon-containing material (e.g., graphite) or a metal. The adhesive of 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. Carbon paste is a mixture of graphite powder and adhesive and can be used in the conductive layer (13, 13B). The conductive layer (13, 13B) can also be formed by a printing method.

[0067] As the metallic conductive layer constituting the cathode electrode layer (14, 14B), copper (Cu), nickel (Ni), silver (Ag), or tin (Sn) can be used, but these metallic conductive layers can be plated layers formed using a plating method. These metallic conductive layers can also be formed by any method such as sputtering. When forming the plated layer by electroless plating, the adhesive conductive layer beneath it may contain a catalytic metal. The catalytic metal is a noble metal that has catalytic activity for electroless plating, and can be palladium (palladium-based material), gold, platinum, rhodium, etc., with palladium being particularly preferred. These may be used alone or mixed in combination of two or more. An additional metal film (thickening) may be formed on the metal film formed by electroless plating or sputtering using an electrolytic plating method.

[0068] Generally, copper plating can be performed using copper sulfate baths, copper pyrophosphate baths, copper cyanide baths, or copper borofluoride baths. Nickel plating can be performed using Watt baths (nickel sulfate), sulfamic acid baths (nickel sulfamate), or total chloride baths (nickel chloride). Tin plating can be performed using sulfuric acid baths or sulfonic acid baths. Various plating methods are known and can be applied to the formation of each plating layer.

[0069] The insulating layer (11, 11B) is made of the same primary resin (e.g., epoxy resin) as the insulating region (10, 10B), and also contains fillers. However, the fillers generally do not penetrate the insulating region (10, 10B). Therefore, the filler content in the insulating region (10, 10B) is smaller than the filler content in the insulating layer (11, 11B).

[0070] The protective layer (15, 15B) consists of a resist material containing a resin, preferably a material containing a resin and an inorganic material. As the inorganic material, a filler such as silica (silicon oxide) can be used. As the resin material, a thermosetting resin such as polyimide or epoxy resin can be used. In this example, a protective layer (15, 15B) made of epoxy resin with silica added is used. The resist material can be a liquid material dissolved in a suitable solvent during manufacturing. Note that the protective layer (15, 15B) can be omitted.

[0071] There are various methods for forming the protective layer (15, 15B). For example, screen printing and gravure printing (transfer) can be used. In this example, screen printing is used. The formation process for each element on the upper surface and the formation process for each element on the lower surface can be performed simultaneously or at different times. Performing them simultaneously can shorten the manufacturing time.

[0072] The insulating portion 30 includes, at least in its upper and lower layers, a constituent material (referred to as material A) included in the upper insulating region 10 and the lower insulating region 10B. The middle layer 30M of the insulating portion 30 mainly contains the constituent material (referred to as material B) of the protective insulator 16. The resin included in material A and the resin included in material B may be the same or different materials.

[0073] Material A consists of a resin-containing resist material and may optionally contain an inorganic filler such as silica. As this resin material, polyimide or a thermosetting resin such as epoxy resin can be used. Epoxy resin can be used as an example of material A.

[0074] Material B consists of a resin containing an inorganic filler such as silica. A thermosetting resin such as epoxy resin can be used as this resin material. As an example of material B, an epoxy resin containing silica filler can be used. The upper layer 30U and lower layer 30D of the insulating part 30 contain epoxy resin contained in materials A and B, and as an example, the filler content is small. The middle layer 30M of the insulating part 30 mainly contains material B, and contains epoxy resin and filler, and 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 included in materials A and B include phenolic resin, methacrylic resin, epoxy resin, silicon resin, polycarbonate, polyethylene terephthalate, polyamide, polyimide, polybutadiene, polyethylene, polystyrene, etc. Furthermore, silica (SiO₂) can be used as an inorganic material constituting the filler. ２ ), aluminum oxide (Al ２ O ３ Examples include aluminum nitride (AlN), etc.

[0075] Next, we will further explain the insulating layers (20) that make up the uppermost layer 20TOP, the intermediate layer 20, and the bottommost layer 20BTM.

[0076] Figure 5(A) shows the planar structure of the glass cloth containing the glass fiber YRN, Figure 5(B) shows the longitudinal cross-sectional structure of the insulating layer (20) containing the glass cloth, and Figure 5(C) is a cross-sectional view perpendicular to the longitudinal direction of the filament FIL.

[0077] As shown in Figure 5(A), the glass cloth contained in the insulating layer (20) has a plain weave structure in which glass threads YRN extending along the longitudinal direction (Y axis) and glass threads YRN extending along the transverse direction (X axis) are woven. The number of glass threads per unit length (25 mm) is denoted as K (threads / 25 mm). The value of K is, for example, 45 (threads / 25 mm). Each glass thread YRN is a yarn formed by bundling and twisting multiple filaments FIL. The number of twists per unit length (25 mm) is exemplary as 1, but can also be 0.5 to 2. The value of K for the top layer 20 TOP is denoted as K(T), the value of K for the intermediate layer 20 is denoted as K(M), and the value of K for the bottom layer 20 BTM is denoted as K(B). The value of K is the number of glass threads extending perpendicular to the length direction contained in a length of 25 mm.

[0078] As shown in Figure 5(B), the total thickness of the insulating layer (20) is dP, and the thickness of the glass cloth is dG. Within the XZ cross-section of the insulating layer (20), cross-sections of multiple filaments FIL extending in the Y-axis direction are observed. Within the XZ cross-section of the insulating layer (20), multiple filaments FIL extending along the X-axis direction are observed.

[0079] Let the dP value of the top layer 20TOP be dP(T), the dP value of the middle layer 20 be dP(M), and the dP value of the bottom layer 20BTM be dP(B). The correlation between the exemplary dP values ​​is dP(M) < dP(T) and can be expressed as dP(M) < dP(B).

[0080] Let the value of dG at the top layer 20TOP be dG(T), the value of dG at the middle layer 20 be dG(M), and the value of dG at the bottom layer 20BTM be dG(B). The correlation between the example dG values ​​is dG(M) < dG(T) and can be expressed as dG(M) < dG(B).

[0081] Let N be the number of bundled filaments (FIL) contained in a single glass fiber (YRN). Let N be the value of N in the top layer (20TOP), N be the value of N in the middle layer (20M), and N be the value of N in the bottom layer (20BTM). The correlation between the values ​​of N is an example of N(M) < N(T) and can be expressed as N(M) < N(G).

[0082] As shown in Figure 5(C), the cross-sectional shape perpendicular to the longitudinal direction of a single filament FIL is circular, and its diameter is denoted as D (μm). The value of D for the uppermost layer 20TOP is D(T), the value of D for the intermediate layer 20 is D(M), and the value of D for the lowermost layer 20BTM is D(B). The correlation between the exemplary values ​​of D is D(M) < D(T), and can also be D(M) < D(B). If the cross-sectional shape perpendicular to the longitudinal direction of a single filament FIL is deformed from a circle, the effective diameter D is defined as the diameter of the circle having the area of ​​that cross-section, and this value of diameter D is defined as the thickness of the filament.

[0083] Evaluation tests were conducted by changing the parameters of the elements constituting the insulating layer (20).

[0084] (Experimental Conditions) First, although the number of solid electrolytic capacitor elements CE shown in Figure 1 is two, following the example in Figure 1, the number of solid electrolytic capacitor elements CE was increased to four, and a solid electrolytic capacitor was manufactured by stacking these elements. The resin contained in the insulating layer (20) is epoxy resin, and the glass threads constituting the glass cloth are made by bundling multiple filaments, with each filament being SiO ２ The silica glass used as the main component was E glass (52% by mass to 56% by mass of SiO). ２ and 12 (mass%) to 16 (mass%) Al ２ O ３ And 20% to 25% by mass of alkaline earth metal oxides and 5% to 10% by mass of B ２ O ３ This is glass containing silica. As the filament material, silica-containing glass such as NE glass, or other known glass can be used, and even when such glass is used for the glass cloth, it is possible to enhance resistance to environmental changes.

[0085] The support substrate, consisting of the bottom layer 20BTM, contains resin and glass cloth. This resin is epoxy resin. This glass cloth has a plain weave structure composed of multiple glass threads. Each glass thread contains bundles of multiple glass filaments. The thickness of one glass filament D(B) = 9 (μm), and the number of glass filaments N(B) contained in one glass thread = 400 (threads). The thickness of the weave structure of the bottom layer 20BTM is dG(B) = 180 μm, and the thickness of the bottom layer 20BTM is dP(B) = 200 (μm). The ratio of resin contained in the bottom layer 20BTM is R(B) = 46 (mass%). The number of glass threads per unit length (25 mm) K (threads / 25 mm) is K(B) = 59 (threads / 25 mm). Furthermore, the parameter range of the components of the lowest layer 20BTM can be set to be the same as the parameter range of the components of the top layer 20TOP, and the same effect can be obtained in this case as well. The parameters of the components of the lowest layer 20BTM contribute to environmental resistance, but even if the parameters of the elements of the lowest layer 20BTM are set to arbitrary values, adjusting at least the parameters of the top layer 20TOP will also increase mechanical strength, thereby increasing environmental resistance.

[0086] The anode electrode layer 8 in the solid electrolytic capacitor element is made of aluminum with a thickness of 25 μm, the dielectric layers (9, 9B) are made of aluminum oxide, and the solid electrolyte layers (12, 12B) are made of a roughened aluminum layer with a thickness of 50 μm impregnated with PEDOT.

[0087] 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 silica filler-containing epoxy resin with a thickness of 20 μm (filler content = 40 (mass%)).

[0088] The insulating regions (10, 10B) consist of an aluminum roughening layer with a thickness of 50 μm containing epoxy resin, the insulating layers (11, 11B) consist of a silica filler-containing epoxy resin with a thickness of 20 μm (filler content = 60 (mass%)), the upper and lower layers of the insulating section 30 are each made of epoxy resin with a thickness of 50 μm, and the middle layer of the insulating section 30 is made of a filler-containing epoxy resin with a thickness of 25 μm (filler content = 70 (mass%)).

[0089] An aluminum sheet with roughened layers formed on its upper and lower surfaces is prepared, and a resist containing epoxy resin and silica filler is printed in a grid pattern to form insulating regions (10, 10B) and insulating layers (11, 11B). PEDOT is then impregnated into the grid openings to form a solid electrolyte layer (12, 12B). On top of this, a copper underlayer is formed by sputtering, and then copper plating is applied to the underlayer to form a cathode electrode layer (14, 14B). Furthermore, a protective layer (15) which will serve as a resist is formed on top of this, and a portion of the protective layer is opened along the Y-axis direction, and the cathode electrode layer within the opening is etched.

[0090] Subsequently, four sheets containing the solid electrolytic capacitor elements created by these processes are prepared and stacked on a support substrate as the bottom layer, as shown in Figure 1, to form a laminated sheet. Grooves GRV, with the negative Z-axis direction as the depth direction, are formed in this laminated sheet by applying a rotating blade to the laminate, as shown in Figure 9. Figure 9 shows the longitudinal cross-sectional configuration of the solid electrolytic capacitor intermediate during groove formation, and the 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, filler-containing epoxy resin is filled into the grooves. The laminate is covered with a protective insulator containing filler-containing epoxy resin. After forming the side electrodes and electrode terminals and performing dicing to create individual parts, a solid electrolytic capacitor covered with a protective insulator is completed. The solid electrolytic capacitor is completed.

[0091] The conditions for the thickness of the insulating layer (20) were set as follows.

[0092] Figure 6 is a diagram showing the parameters of the elements that make up the insulating layer (top layer).

[0093] In Data 1 to Data 30, the filament diameter D(T) was varied from 4 (μm) to 9 (μm). The number of filament bundles N(T) contained in a single glass thread was varied from 50 (filaments) to 400 (filaments). The number of unidirectional glass threads per unit length contained in the glass cloth (glass cloth weave density) K(T) was varied from 45 (filaments / 25 mm) to 72 (filaments / 25 mm). When the number of warp and weft threads are different, the average number of unidirectional glass threads K is given by the average of these values. The thickness dG(T) of the glass cloth was varied from 13 (μm) to 180 (μm). In Data 30, two glass cloths with a thickness of 55 (μm) were used, resulting in a total glass cloth thickness of 110 (μm).

[0094] The resin ratio R(T) (= mass of resin / (mass of resin + glass cloth)) contained in the insulating layer (20) was varied from 46 (mass%) to 100 (mass%). The thickness dP(T) of the insulating layer (20) constituting the uppermost layer was varied from 20 (μm) to 240 (μm). In addition, in the numerical values ​​in each table, for example, the thickness dP(T) in data 18, if the same result was obtained within a certain range, a hyphen is used between the numbers, such as 140-180.

[0095] Figure 7 is a diagram showing the parameters of the elements that make up the insulating layer (intermediate layer).

[0096] In data 1 to data 30, the filament diameter D (M) was varied from 4 (μm) to 7.4 (μm). The number of filament bundles N (M) contained in a single glass thread was varied from 50 (filaments) to 400 (filaments). The number of unidirectional glass threads per unit length contained in the glass cloth (glass cloth weave density) K (M) was varied from 46 (filaments / 25 mm) to 95 (filaments / 25 mm). When the number of warp and weft threads differed, the average number of unidirectional glass threads was given by the average of these values. The thickness dG (M) of the glass cloth was varied from 13 (μm) to 125 (μm). The resin ratio R (M) (= mass of resin / (mass of resin + glass cloth)) contained in the insulating layer (20) was varied from 47 (mass%) to 100 (mass%). The thickness dP(M) of the insulating layer (20) constituting the intermediate layer was varied from 20 (μm) to 180 (μm).

[0097] (Evaluation and Results) Solid electrolytic capacitor elements were stacked, the stacked structure was sealed with resin, and then diced to separate the individual solid electrolytic capacitors. The solid electrolytic capacitors were then evaluated. The evaluation items were peel resistance, adhesion, and thermal shock resistance.

[0098] (1) Peel resistance evaluation In the peel resistance evaluation, when forming the groove as described above, grooves are formed using a cutting blade with a width of 0.3 mm and a cutting speed of 5 mm / second, and the condition in this case is observed and evaluated.

[0099] (Evaluation A): In the peel resistance evaluation, if the insulating layer (20TOP) located on the surface of the laminate does not peel off when forming grooves under the above conditions, it will be judged as a good product and given an evaluation of (Evaluation A).

[0100] (Evaluation B): In the peel resistance evaluation, if the insulating layer (20TOP) peels off at a cutting speed of 5 mm / second but not at 1 mm / second during groove formation under the above conditions, the product is judged to be of reduced quality (Evaluation B).

[0101] (Evaluation C): In the peel resistance evaluation, if peeling occurs 1 to 2 times out of 10 trials even when the insulating layer (20TOP) is cut at a cutting speed of 1 mm / second during groove formation under the above conditions, the product is judged to be of further reduced quality (Evaluation C).

[0102] (Evaluation D): In the delamination resistance evaluation, if delamination occurs in 3 or more out of 10 trials even at a cutting speed of 1 mm / second during groove formation under the above conditions, the product is judged to be defective and given an evaluation of (Evaluation D). Figure 10 is a plan view of the groove surrounding structure (defective product: evaluation D (data 13)), and Figure 11 is a plan view of the groove surrounding structure (good product: evaluation A (data 1)). In the device with evaluation D, delamination regions of the insulating layer are formed on both sides of the groove GRV formed by the rotating blade, and if the dimensions (DF1, DF2) in the X-axis direction of these regions are 20 μm or more, it is judged that delamination has occurred. In the device with evaluation A, no delamination regions of the insulating layer are formed.

[0103] (2) Adhesion Evaluation (Evaluation A): In the adhesion evaluation, if all insulating layers (20) and solid electrolytic capacitor elements are in close contact with the finished product after lamination and encapsulation, and if there is no deterioration in product characteristics (variation of 10% or more in all characteristic values ​​(capacitance, Tanδ (dielectric loss tangent), ESR (equivalent series resistance))) after water absorption for 168 hours or more in an environment of 30°C and 60% humidity (equivalent to JEDEC-MSL3) and passing through a reflow furnace with a maximum temperature of 260°C, then the product is judged as a good product and given an evaluation of (Evaluation A). An LCR meter was used to evaluate the characteristic values. In (Evaluation A), when observed with a 500x electron microscope, all insulating layers (20) and solid electrolytic capacitor elements are in close contact with the insulating layers (20) between solid electrolytic capacitor elements, and no voids are observed.

[0104] (Evaluation B): In reflow after water absorption subject to the environmental burden equivalent to MSL3 as described above, no degradation of characteristics is observed (i.e., the variation in the above characteristic values ​​is less than 10%), but if voids are observed in the insulating layer (20) between solid electrolytic capacitor elements in the above-mentioned microscopic observation, the product will be judged as (Evaluation B).

[0105] (Evaluation C): If the product exhibits performance degradation (i.e., a variation of 10% or more in the above-mentioned characteristic values) after reflow processing with water absorption subject to the environmental burden equivalent to MSL3 as described above, but no performance degradation is observed when reflow processing is performed after drying at 120°C for 30 minutes, the product will be judged as (Evaluation C).

[0106] (Evaluation D): In both cases—when reflow furnace is run after water absorption as described above, and when reflow furnace is run after drying as described above—if the characteristics deteriorate (i.e., the change in the above characteristic value is 10% or more) the product is judged as (Evaluation D). In (Evaluation D) products, fracture and delamination of the solid electrolytic capacitor elements between layers can be observed by microscopic observation as described above. Fracture and delamination can be observed not only in (Evaluation D) products but also in (Evaluation C) products. Significant fracture and delamination are observed in (Evaluation D) products. Delamination may also be observed in (Evaluation B) products.

[0107] Figure 12 shows a micrograph of the longitudinal cross-sectional structure of a solid electrolytic capacitor intermediate (not a good product: evaluation C (data 6)), and Figure 13 shows a micrograph of the longitudinal cross-sectional structure of a solid electrolytic capacitor intermediate (good product: evaluation A (data 1)). In the device of evaluation C, the insulating layer (20) is partially peeled off, and spaces (D201, D202) are formed between the insulating layer (20) and the solid electrolytic capacitor element (CE). Peeling is determined to have occurred when the maximum dimension of the thickness direction (Z-axis direction) of each space (D201, D202) is 2 (μm) or more. In the device of evaluation A, the above spaces (D201, D202) are not formed, and no voids are observed.

[0108] (3) Thermal shock resistance evaluation (Evaluation A): In the thermal shock resistance evaluation, a thermal shock test is performed in which the temperature change from -55°C to 125°C is repeated 2000 times. If the above characteristic change between the initial state and after the test is within 10%, the product is judged to be (Evaluation A).

[0109] (Evaluation B): In the thermal shock resistance evaluation, a thermal shock test is performed in which the temperature change from -55°C to 125°C is repeated 2000 times. If the above characteristic variation is within 10% in the process up to 1000 cycles, and if the variation is 10% or more under conditions of 2000 cycles or less, the product will be judged as (Evaluation B).

[0110] (Evaluation C): In the thermal shock resistance evaluation, if the conditions for (Evaluation B) are not met, and a thermal shock test is performed in which the temperature change from -40°C to 105°C is repeated 2000 times, and the above characteristic change between the initial and post-test processes is within 10% in the process up to 1000 cycles, the product will be judged as (Evaluation C).

[0111] (Evaluation D): In the thermal shock resistance evaluation, a thermal shock test is performed in which the temperature change from -40°C to 105°C is repeated 1000 times. If the above characteristic value changes by 10% or more in less than 1000 cycles, the product is judged to be (Evaluation D).

[0112] Figure 8 is a table showing the evaluation results of solid electrolytic capacitors using each parameter.

[0113] The experimental data for structures with evaluations of (A, A, A) for peel resistance, adhesion, and thermal shock resistance are data 1, 2, 3, 4, 17, 18, 19, 20, 21, 22, 26, 28, and 30. The data for which the evaluation is other than (A, A, A) are data 5-16, 23-25, 27, and 29.

[0114] Regarding the top layer (bottom layer) shown in Figure 6, the data that received these ratings (A, A, A) satisfy at least the following conditions.

[0115] ・5.3(μm)≦D(T)≦9(μm) ・200(pieces)≦N(T)≦408(pieces) ・55(μm)≦dG(T)≦180(μm) ・46(mass%)≦R(T)≦71(mass%)・65 (μm)≦dP(T)≦240 (μm)

[0116] Furthermore, the range for K must satisfy at least the following conditions. If the value of K is within the following range, a result of (A, A, A) will be obtained, but if it is within the range of realistic weave structure values, it is considered that an effect of evaluation B or C or higher will be obtained for at least all evaluation items. • 45 (threads / 25 mm) ≤ K(T) ≤ 60 (threads / 25 mm)

[0117] Here, even if there is an error of at least 10% in the value of D(T), it is thought that there will be no significant change in strength / restraining force (elastic modulus) and linear expansion coefficient, and a similar effect will be obtained. In the case of such an error, the decimal places can be rounded. Similarly, it is thought that a similar effect will be obtained if there is a 10% error in the values ​​of N(T), dG(T), R(T), and dP(T). ・5 (μm) ≤ D(T) ≤ 10 (μm) ・180 (threads) ≤ N(T) ≤ 449 (threads) ・50 (μm) ≤ dG(T) ≤ 198 (μm) ・41 (mass%) ≤ R(T) ≤ 78 (mass%) ・59 (μm) ≤ dP(T) ≤ 264 (μm)

[0118] Furthermore, regarding the lower limit of the N(T) value, it varies depending on D(T), but from the perspective of ensuring that the strength, restraining force (elastic modulus), and coefficient of linear expansion are defined within the above parameter range, a value of 150 (threads) or more is considered acceptable. Regarding the upper limit, there is no upper limit from the perspective of strength increase, but from the perspective of being able to stably produce glass yarn, a value of 500 (threads) or less is considered acceptable, as it is believed that an effect of at least a B or C rating will be obtained for all evaluation items. Also, regarding the upper limit of the dG(T) value, it is considered that a similar effect can be obtained even if the third significant figure is rounded. In this case, the preferred range of parameters is as follows.

[0119] ・5(μm)≦D(T)≦10(μm) ・150(pieces)≦N(T)≦500(pieces) ・50(μm)≦dG(T)≦200(μm) ・41(mass%)≦R(T)≦78(mass%)・59 (μm)≦dP(T)≦264 (μm)

[0120] Regarding the uppermost (lowest) layer, the strength / restraining force (elastic modulus) and the coefficient of linear expansion are thought to affect peel resistance, adhesion, and thermal shock resistance, and it is believed that the desired effect can be obtained by adjusting N(T) and D(T), respectively. Therefore, when D(T) is 10 μm (upper limit), it is thought that an effect can be achieved even with N(T) of around 100 strands. Furthermore, the effect of the restraining force due to the thickness of the uppermost (lowest) layer (dP(T)) is weaker than the effect of the restraining force due to the glass fibers, so it is thought that a similar effect can be obtained in terms of restraining element deformation even if this parameter range (59 (μm) ≤ dP(T) ≤ 264 (μm)) is excluded. Therefore, a solid electrolytic capacitor with high environmental resistance can be obtained within the following range.・5 (μm)≦D(T)≦10 (μm) ・100 (pieces)≦N(T)≦500 (pieces) ・50 (μm)≦dG(T)≦200 (μm) ・41 (mass%)≦R(T)≦78 (mass%)

[0121] With respect to D(T) and N(T), the following relationship may preferably be satisfied. Note that the value of D(T) × D(T) × N(T) can be calculated from the data, and the value may be rounded to the nearest whole number. ・5000 (μm ２ ・Book)≦D(T)×D(T)×N(T)≦40000(μm ２ (Book)

[0122] In other words, it is believed that the same effects as described above can be obtained in the following range as well: • 5000 (μm) ２ ・Book)≦D(T)×D(T)×N(T)≦40000(μm ２ ・Book) ・50 (μm)≦dG(T)≦200 (μm) ・41 (mass%)≦R(T)≦78 (mass%)

[0123] Regarding the intermediate layer shown in Figure 7, the data that received these ratings (A, A, A) satisfy at least the following conditions.

[0124] ・4 (μm)≦D (M)≦5.3 (μm) ・50 (pieces)≦N (M)≦100 (pieces) ・13 (μm)≦dG (M)≦35 (μm) ・70 (mass%)≦R (M)≦75 (mass%)・20(μm)≦dP(M)≦40(μm)

[0125] Furthermore, the range for K must satisfy at least the following conditions. If the value of K is within the following range, a result of (A, A, A) will be obtained, but if it is within the range of realistic weave structure values, it is considered that an effect of evaluation B or C or higher will be obtained for at least all evaluation items. • 60 (threads / 25 mm) ≤ K(M) ≤ 95 (threads / 25 mm)

[0126] Here, it is thought that a similar effect can be obtained even if there is at least a 10% error in the value of D(M). In such cases, the decimal places can be rounded. Similarly, it is thought that a similar effect can be obtained if there is a 10% error in the values ​​of N(M), dG(M), R(M), and dP(M). That is, as follows:

[0127] ・4 (μm)≦D (M)≦6 (μm) ・45 (pieces)≦N (M)≦110 (pieces) ・12 (μm)≦dG (M)≦39 (μm) ・63 (mass%)≦R (M)≦83 (mass%)・18 (μm)≦dP(M)≦44 (μm)

[0128] Furthermore, regarding the upper limit of the value of N(M), if it is smaller than N(T), the effect will be significant. However, from the perspective that the coefficient of linear expansion is about the same as in the parameter range described above, it is considered that if it is 150 (lines) or less, an effect of evaluation B or C or higher can be obtained for at least all evaluation items. The preferred range of parameters in this case is as follows.

[0129] ・4 (μm)≦D (M)≦6 (μm) ・45 (pieces)≦N (M)≦150 (pieces) ・12 (μm)≦dG (M)≦39 (μm) ・63 (mass%)≦R (M)≦83 (mass%)・18 (μm)≦dP(M)≦44 (μm)

[0130] Regarding the intermediate layer, its strength / restraining force (elastic modulus) and coefficient of linear expansion are thought to affect peel resistance, adhesion, and thermal shock resistance. By adjusting N(M) and D(M), the desired effect can be obtained. Therefore, even if D(M) is 10 μm (upper limit), an effect can be expected if N(M) is around 100 fibers. Furthermore, the influence of the restraining force due to the thickness of the intermediate layer (dP(M)) is weaker than the influence of the restraining force due to the glass fibers. Therefore, even if this parameter range (18 (μm) ≤ dP(M) ≤ 44 (μm)) is excluded, a similar effect on restraining element deformation can be obtained. Thus, a solid electrolytic capacitor with high environmental resistance can be obtained within the following range: 4 (μm) ≤ D(M) ≤ 10 (μm) 45 (fibers) ≤ N(M) ≤ 150 (fibers) 12 (μm) ≤ dG(M) ≤ 39 (μm) 63 (mass%) ≤ R(M) ≤ 83 (mass%)

[0131] With respect to D(M) and N(M), the following relationship may preferably be satisfied: • 500 (μm) ２ ・Book)≦D(M)×D(M)×N(M)≦6500(μm ２ (Note: The value of D(M) × D(M) × N(M) can be calculated from the data, and the value may be rounded to the nearest whole number. Also, in the intermediate layer, N(M) is smaller than N(T).)

[0132] In other words, it is believed that the same effects as described above can be obtained in the following ranges as well: • N(M) < N(T) • 500 (μm) ２ ・Book)≦D(M)×D(M)×N(M)≦6500(μm ２ ・Book), ・12 (μm)≦dG(M)≦39 (μm), ・63 (mass%)≦R(M)≦83 (mass%)

[0133] Data 13 and Data 14 are the data that have a rating of D in either item, and these are devices in which the top layer 20 TOP does not contain glass cloth. In other words, if the top and bottom insulating layers (20) contain glass cloth, the production of defective products (rating D) can be suppressed. Even if the intermediate layer 20 does not contain glass cloth, it is possible to manufacture devices that do not become defective products (rating D), but if it contains glass cloth, the device will have an even better rating.

[0134] Preferably, the thickness of the glass cloth in the X-axis direction of the intermediate layer 20 is made smaller than the thickness of the glass cloth in the uppermost or lowermost insulating layer (dG(M) < dG(T)), the filament thickness D(M) is also made thin so as to satisfy D(M) < D(T), and the number of filaments N(M) contained in one glass thread is also set small so as to satisfy N(M) < N(T). In this case, the coefficient of linear expansion of the intermediate layer 20 becomes larger than the coefficient of linear expansion of the uppermost or lowermost insulating layer. Therefore, in the vicinity of the intermediate layer 20, it is easy to change in accordance with the thermal expansion of the solid electrolytic capacitor element, while the uppermost and lowermost layers, which are farther from the solid electrolytic capacitor element and can suppress overall thermal expansion, become less susceptible to thermal expansion, thus increasing thermal shock resistance.

[0135] Even when the above range is met, data 6-8 and data 10 have evaluation items other than evaluation A. For these parameters as well, similarly to the 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 from the values ​​in the chart. It is believed that similar effects can be obtained even if the lower limit includes an error of -10% and the upper limit includes an error of +10%.

[0136] The thickness parameters D(T), dG(T), dP(T), D(M), dG(M), and dP(M) are determined by observation using an optical microscope. If the surface of each layer is rough and uneven, the thickness is determined using the average height position obtained by the least squares method. The resin ratio parameters R(T) and R(M) are determined by sampling the target portion, placing it in a crucible, firing it in air at 600°C for 1 hour, measuring the weight change of the sample, and then measuring the ash content to determine the resin ratio.

[0137] The parameters of the bottom layer 20BTM constituting the support substrate are not particularly limited, but even if they have the same parameters as the top layer, it is thought that similar effects can be obtained, in which case at least the following conditions can be satisfied: • 5 (μm) ≤ D (B) ≤ 10 (μm) • 150 (lines) ≤ N (B) ≤ 500 (lines) • 50 (μm) ≤ dG (B) ≤ 200 (μm) • 41 (mass%) ≤ R (B) ≤ 78 (mass%) • 59 (μm) ≤ dP (B) ≤ 264 (μm)

[0138] Next, we will briefly explain the manufacturing method of solid electrolytic capacitors.

[0139] First, a solid electrolytic capacitor sheet having a laminated structure of solid electrolytic capacitor elements CE as shown in Figure 2 is manufactured. This sheet does not contain insulating portions 30, and these areas are filled with the same material as the insulating regions (10, 10B). The manufacturing method of the solid electrolytic capacitor sheet comprises (a) a metal sheet preparation step, (b) an insulating region 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 splitting step of the cathode electrode layer, and these steps are performed sequentially.

[0140] (a) In the metal sheet preparation step, a metal sheet is prepared in which roughened layers are formed on the upper and lower surfaces of the anode electrode layer 8. The roughened layers are first formed by roughening both sides of the metal sheet by etching or the like, and then an oxide layer is formed on these surfaces by chemical conversion treatment (oxide film formation treatment and / or anodic oxidation) on both sides of the metal sheet. On the upper surface of the anode electrode layer 8, a first dielectric layer (oxide layer: Al in this example) is formed. ２ O ３ A layer is formed, and on the lower surface, a second dielectric layer 9B (oxide layer: Al in this example) is formed. ２ O ３ A layer is formed.

[0141] (b) In the process of forming the insulating region, a resist (resin + filler) having a grid pattern is applied to the surface of the roughened layer, allowing the resin to penetrate into the interior of the roughened layer and forming an insulating region (10, 10B). The filler does not penetrate into the interior of the insulating region (10, 10B), but the resist containing the filler remains on its surface, forming an insulating layer (11, 11B). Various methods are known for applying the resist. For example, screen printing, gravure printing, and spray coating methods are known. In this example, screen printing is used. The material of the resist is material A (e.g., a mixture of epoxy resin and silica filler). Other fillers known to be used include alumina and aluminum hydroxide.

[0142] (c) In the process of forming the solid electrolyte layer, a conductive polymer is supplied into the openings of the lattice pattern and allowed to penetrate into the roughened layer to form the solid electrolyte layer (12, 12B). Various methods are known for introducing the conductive polymer. For example, coating methods, chemical oxidation polymerization methods, and electrolytic polymerization methods are known.

[0143] (d) In the step of forming the conductive layer, conductive layers (13, 13B) are formed on the solid electrolyte layers (12, 12B). Each conductive layer may be a single layer or two or more layers. As a method of formation, a method of applying the conductive layer material (e.g., carbon paste) can be used. Screen printing, gravure printing (transfer), or a supply method using a dispenser can be used.

[0144] (e) In the cathode electrode layer formation process, cathode electrode layers (14, 14B) are formed on the conductive layers (13, 13B) using a plating method or the like. When forming the cathode electrode layer, first a highly adhesive underlayer such as copper (Cu) or nickel-chromium alloy (NiCr) is formed by sputtering, and then a plating layer is formed on the underlayer. In this example, the material of the plating layer is copper (Cu).

[0145] (f) In the protective layer formation step, a protective film (15, 15B) made of patterned resist is formed on the cathode electrode layer (14, 14B). Screen printing or gravure printing (transfer) can be used to form the protective layer.

[0146] (g) In the etching division process of the cathode electrode layer, the protective film (15, 15B) is used as a mask to etch a portion of the cathode electrode layer (14, 14B) so that a portion of the insulating layer (11, 11B) is exposed, thereby dividing it into multiple rectangular regions. As the etching solution, an aqueous solution of ferric chloride, an aqueous solution of copper chloride, or a mixture of sulfuric acid and hydrogen peroxide can be used. Through these processes, a solid electrolytic capacitor sheet is manufactured. Note that the processing steps for the elements above the anode electrode layer 8 and the processing steps for the elements below it may be performed simultaneously or separately.

[0147] Next, multiple solid electrolytic capacitor sheets are stacked on a cured glass cloth impregnated epoxy resin (the bottom layer 20BTM as a support substrate shown in Figure 1). An adhesive insulating layer (20) (intermediate layer), as shown in the same figure, is placed between each sheet, between the sheets and the support substrate, and on the top sheet. The top layer 20TOP may be laminated and cured by stacking a predetermined glass cloth impregnated epoxy resin (uncured, prepreg material), or a cured glass cloth impregnated epoxy resin (= glass epoxy substrate) may be stacked (laminated and cured) with the intermediate layer 20 (uncured glass cloth impregnated epoxy resin). These sheets are bonded together to produce a laminated sheet. A rotary blade is applied to the laminated sheet to form a groove GRV along the Y axis direction, with the negative Z direction being the depth direction, as shown in Figure 9. Similarly, a rotary blade is applied to the laminated sheet to form a groove along the X axis direction, with the negative Z direction being the depth direction. An 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 an aqueous sodium hydroxide solution or an acidic solution such as sulfuric acid can be used. Appropriate additives may be added to the etching solution as needed.

[0148] The insulating material constituting the protective insulator 16 is filled into the grooves, 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 grooves to form the insulating portion 30. In this filling process, insulating resin is supplied to the upper surface of the laminated sheet, and pressure is applied in the Z-axis direction to fill the insulating resin into the grooves and spaces. The form of the supplied insulating resin may be liquid or solid sheet. As a filling method, a compression molding method, a transfer molding method, or an injection molding method using liquid insulating resin can be used. As a filling method, a method in which a sheet-like resin encapsulant is attached to the surface of the laminated sheet and the resin encapsulant is flattened by pressing can also be used.

[0149] Next, a rotating blade is applied to the laminated sheet, with the positive Z-axis direction as the depth direction, and grooves formed along the Y-axis direction, exposing one side surface where the first side electrode E1 will be formed and the other side surface where the second side electrode E2 will be formed. Subsequently, the first side electrode E1 and the second side electrode E2 are formed on the inner surface of the grooves by a plating method or the like. The groove formation position at this time is such that the first side electrode E1 can contact one side surface of the anode electrode layer 8, and the second side electrode E2 can contact the other side surface of the cathode electrode layer (14, 14B). Finally, the rotating blade is applied to the laminated sheet to perform dicing in a grid pattern, and individual solid electrolytic capacitors are cut out. The anode terminal 1 and cathode terminal 2 can be formed by patterning electrode material on the bottom layer in the process before the formation of the side electrodes, after the laminated body is formed by stacking fixed electrolytic capacitor elements.

[0150] As described above, the first embodiment of the solid electrolytic capacitor comprises a laminate containing a plurality of stacked solid electrolytic capacitor elements, a first layer fixed to the first surface of the laminate, and a second layer fixed to the second surface of the laminate, wherein the first layer contains a first resin and a first glass cloth, and the second layer contains a second resin and a second glass cloth.

[0151] In the first embodiment of the solid electrolytic capacitor, at least the first glass cloth has a plain weave structure composed of a plurality of glass threads, and each glass thread contains a bundle of multiple glass filaments, and the thickness D(T) of one glass filament, the number of glass filaments N(T) contained in one glass thread, the thickness dG(T) of the weave structure, the ratio R(T) of resin contained in the first layer, and the thickness dP(T) of the first layer satisfy the following relationship: 5(μm) ≤ D(T) ≤ 10(μm), 100(threads) ≤ N(T) ≤ 500(threads), 50(μm) ≤ dG(T) ≤ 200(μm), 41(mass%) ≤ R(T) ≤ 78(mass%).

[0152] The third embodiment of the solid electrolytic capacitor further comprises 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.

[0153] In the fourth form of solid electrolytic capacitor, the third glass cloth has a plain weave structure composed of multiple glass threads, and in the third glass cloth, multiple glass filaments are bundled together and contained in one glass thread, and the thickness D(M) of one glass filament, the number of glass filaments N(M) contained in one glass thread, and the thickness dG(M) of the weave structure satisfy the following relationship: dG(M) < dG(T), D(M) < D(T), N(M) < N(T).

[0154] In the fifth form of solid electrolytic capacitor, D(M), N(M), dG(M), and the ratio R(M) of resin contained in the intermediate layer satisfy the following relationships: 4(μm) ≤ D(M) ≤ 6(μm), 10(particles) ≤ N(M) ≤ 150(particles), 12(μm) ≤ dG(M) ≤ 39(μm), and 63(mass%) ≤ R(M) ≤ 83(mass%).

[0155] In the sixth form of solid electrolytic capacitor, the ratio of D(M), N(M), dG(M), and the resin R(M) contained in the intermediate layer are given by the following relationship: 500 (μm) ２ ・Book)≦D(M)×D(M)×N(M)≦6500(μm ２ The following conditions are met: 12 (μm) ≤ dG (M) ≤ 39 (μm), and 63 (mass%) ≤ R (M) ≤ 83 (mass%).

[0156] In the seventh form of solid electrolytic capacitor, D(T) and N(T) have the following relationship: 5000 (μm ２ ・Book)≦D(T)×D(T)×N(T)≦40000(μm ２ • It satisfies the requirement of a book.

[0157] Furthermore, within the range of various parameters, the range of any parameter P is P ｍｉｎ ≤P ≤P ｍａｘ If given by, (P ｍｉｎ +ΔP) ≤ P ≤ (P ｍａｘ -ΔP), ΔP = (P ｍａｘ -P ｍｉｎThe error can be set to ) × R%, with R=10, or R=20, R=30, or R=40. Also, if any parameter P is a specific numerical value, the error range can be set to P × 95% ≤ P ≤ P × 105%.

[0158] While various exemplary embodiments have been described above, the present invention is not limited to these exemplary embodiments, and various omissions, substitutions, and modifications may be made. Furthermore, elements from different embodiments can be combined to form other embodiments. From the above description, it will be understood that various embodiments of this disclosure are described herein and can be modified in various ways without departing from the scope and spirit of this disclosure. Therefore, the various embodiments disclosed herein are not intended to be limiting, and the true scope and spirit are indicated by the claims.

[0159] 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.

Claims

1. A solid electrolytic capacitor comprising: a laminate including 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, wherein the first layer includes a first resin and a first glass cloth, and the second layer includes 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 plain weave structure composed of a plurality of glass threads, and each glass thread contains a bundle of a plurality of glass filaments, and the thickness D(T) of one glass filament, the number of glass filaments N(T) contained in one glass thread, the thickness dG(T) of the weave structure, and the ratio R(T) of resin contained in the first layer satisfy the following relationship: 5(μm) ≤ D(T) ≤ 10(μm), 100(threads) ≤ N(T) ≤ 500(threads), 50(μm) ≤ dG(T) ≤ 200(μm), and 41(mass%) ≤ R(T) ≤ 78(mass%).

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

4. The third glass cloth has a plain weave structure composed of a plurality of glass threads, wherein in the third glass cloth, a plurality of glass filaments are bundled together and contained in one glass thread, and the thickness D(M) of one glass filament, the number of glass filaments N(M) contained in one glass thread, and the thickness dG(M) of the weave structure satisfy the following relationships: dG(M) < dG(T), D(M) < D(T), N(M) < N(T), the solid electrolytic capacitor according to claim 3.

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

6. The ratio of D(M), N(M), dG(M), and the resin contained in the intermediate layer R(M) are given by the following relationship: 500(μm) ２ ・Book)≦D(M)×D(M)×N(M)≦6500(μm ２ A solid electrolytic capacitor according to claim 4, satisfying the following conditions: 12 (μm) ≤ dG (M) ≤ 39 (μm), and 63 (mass%) ≤ R (M) ≤ 83 (mass%).

7. D(T) and N(T) have the following relationship: 5000 (μm) ２ ・Book)≦D(T)×D(T)×N(T)≦40000(μm ２ A solid electrolytic capacitor according to claim 2, satisfying the following conditions:

Images