Solid electrolytic capacitors

Abstract

Solid electrolytic capacitors, which have high resistance to environmental changes, are expected to be a promising technology. [Solution] The solid electrolytic capacitor comprises a first solid electrolyte layer 12 disposed between the anode electrode layer 8 and the upper cathode electrode layer 14, a second solid electrolyte layer 12B disposed between the anode electrode layer 8 and the lower cathode electrode layer 14B, a first side electrode E1 in contact with the first side surface of the anode electrode layer 8, a second side electrode E2 in contact with the side surface of the upper cathode electrode layer 14 and the side surface of the lower cathode electrode layer 14B, an insulating portion 30 containing resin interposed between the second side surface of the anode electrode layer 8 and the second side electrode E2, a first insulating layer 11 containing resin and filler interposed between the upper cathode electrode layer 14 and the insulating portion 30, and a second insulating layer 11B containing resin and filler interposed between the lower cathode electrode layer 14B and the insulating portion 30. The filler content in the first insulating layer 11, the second insulating layer 11B, and the insulating portion 30 is set.

Description

[Technical Field]

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

[0002] Patent document 1 discloses a solid electrolytic capacitor. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2019 / 087692 [Overview of the project] [Problems that the invention aims to solve]

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

[0005] The first solid electrolytic capacitor of this disclosure comprises: a first solid electrolyte layer disposed between an anode electrode layer and a first cathode electrode layer; a second solid electrolyte layer disposed between the anode electrode layer and a second cathode electrode layer; a first side electrode in contact with the first side surface of the anode electrode layer; a second side electrode in contact with the side surface of the first cathode electrode layer and the side surface of the second cathode electrode layer; an insulating portion containing resin interposed between the second side surface of the anode electrode layer and the second side electrode; a first insulating layer containing resin and filler interposed between the first cathode electrode layer and the insulating portion; and a second insulating layer containing resin and filler interposed between the second cathode electrode layer and the insulating portion, wherein the filler content C in the first insulating layer Z1 (mass%), filler content C in the second insulating layer Z2 (mass%), and the filler content C in the insulating portion. M0 (mass%) is C M0 <C Z1 , C M0 <C Z2Satisfies

[0006] The second solid electrolytic capacitor of the present disclosure includes a first solid electrolyte layer disposed between an anode electrode layer and a first cathode electrode layer, a second solid electrolyte layer disposed between the anode electrode layer and a second cathode electrode layer, a first side electrode in contact with a first side surface of the anode electrode layer, a second side electrode in contact with side surfaces of the first cathode electrode layer and the second cathode electrode layer, an insulating portion containing resin and intervening between a second side surface of the anode electrode layer and the second side electrode, a first insulating layer containing resin and a filler and intervening between the first cathode electrode layer and the insulating portion, and a second insulating layer containing resin and a filler and intervening between the second cathode electrode layer and the insulating portion. The insulating portion includes a first resin layer located on the first insulating layer side, a second resin layer located on the second insulating layer side, and an intermediate resin layer intervening between the first resin layer and the second resin layer and having a filler content higher than that of either the first resin layer or the second resin layer. The filler content C Z1 (mass%) in the first insulating layer, the filler content C Z2 (mass%) in the second insulating layer, the filler content C M1 (mass%) in the first resin layer, the filler content C M2 (mass%) in the second resin layer, and the filler content C A1 (mass%) in the intermediate resin layer satisfy C M1 <C Z1 、C M2 <C Z2 、C M1 <C A1 、C M2 <C A1 Satisfies [Advantages of the Invention]

[0007] According to the solid electrolytic capacitor of the present disclosure, the resistance to environmental changes is increased. [Brief Description of the Drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a longitudinal sectional configuration of a solid electrolytic capacitor. [Figure 2]Figure 2 shows the longitudinal cross-sectional configuration of a solid electrolytic capacitor element. [Figure 3] Figure 3 is an enlarged view of the region near the second side electrode in a solid electrolytic capacitor element (first example). [Figure 4] Figure 4 is an enlarged view of the region near the second side electrode in a solid electrolytic capacitor element (second example). [Figure 5] Figures 5(A), 5(B), and 5(C) schematically show the vicinity region of the second side electrode of the fixed electrolytic capacitor element according to the first example, the second example, and the comparative example. [Figure 6] Figure 6 is a chart showing the parameters and evaluation results for each element in the first example. [Figure 7] Figure 7 is a chart showing the parameters and evaluation results for each element in the second example. [Figure 8] Figure 8 is a chart showing the parameters and evaluation results for each element in the second example. [Modes for carrying out the invention]

[0009] 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.

[0010] Figure 1 shows the longitudinal cross-sectional configuration of a solid electrolytic capacitor.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 also increases the mechanical strength of the solid electrolytic capacitor and, together with the protective insulator 16, functions as a barrier to protect the internal layers from external contaminants. By having the bottom layer 20BTM and the top layer 20TOP, the solid electrolytic capacitor can suppress the 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 the stress generated inside the laminate in response to environmental changes.

[0016] 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.

[0017] Figure 2 shows the longitudinal cross-sectional configuration of a solid electrolytic capacitor element CE.

[0018] A single solid electrolytic capacitor element CE is equipped with an anode electrode layer 8.

[0019] The solid electrolytic capacitor element CE comprises an upper cathode electrode layer 14 and a solid electrolyte layer 12 positioned between the anode electrode layer 8 and the upper cathode electrode layer 14 (first cathode electrode layer) in the upper region of the anode electrode layer 8. The solid electrolyte layer 12 is composed of a roughened layer containing a conductive polymer. A dielectric layer 9 is formed in the region near the interface between the anode electrode layer 8 and the solid electrolyte layer 12, following the uneven shape inside the roughened layer of the solid electrolyte layer 12. A residual conductive polymer layer that did not penetrate into the roughened layer during addition may be formed on the upper surface of the solid electrolyte layer 12, 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 of the solid electrolytic capacitor element CE in the X-axis direction. 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 upper surface of the upper cathode electrode layer 14.

[0020] In the upper region of the anode electrode layer 8, a pair of upper insulating regions 10 are formed as mixed regions 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 which constitutes the roughened layer, and the first resin is a thermosetting resin such as epoxy resin.

[0021] 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 in the X-axis direction of the solid electrolytic capacitor element CE. 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.

[0022] 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).

[0023] 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.

[0024] The material of the insulating portion 30 includes the same material as the protective insulator 16, preferably containing a filler in the resin (e.g., epoxy resin). In the first example, the insulating portion 30 is composed of a single layer, while in the second example, the insulating portion 30 has a three-layer structure consisting of an upper layer 30U, a middle layer 30M, and a lower layer 30D. In the first example, the three-layer structure of the insulating portion 30 in Figure 2 becomes a single-layer structure.

[0025] One example of the material for the anode electrode layer 8 is aluminum. Another example of the material for the roughened layer formed on the upper and lower surfaces of the anode electrode layer 8 is aluminum. Another example of the material for the dielectric layer 9 formed near the surface of the anode electrode layer 8 is aluminum oxide (Al2O3). Another example of the material for the solid electrolyte layer 12 is a roughened aluminum layer into which a conductive polymer has been introduced. Another example of the material for the upper cathode electrode layer 14 is copper. The materials of each element on the lower side of the anode electrode layer 8 are the same as the materials of the corresponding elements on the upper side.

[0026] The mixed regions (insulating regions (10,10B)) on the first and second side electrode sides contain 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 and second side electrode sides contain a filler such as silica and a resin (a thermosetting resin such as epoxy resin).

[0027] The first side electrode E1 is in contact with the first side surface 81 of the anode electrode layer 8. The second side electrode E2 is in contact with the second side surface 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 depends on the stress generated in the region near the second side electrode E2.

[0028] Figure 3 is an enlarged view of the region near the second side electrode in a solid electrolytic capacitor element (first example).

[0029] 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 fillers. 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.

[0030] 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 partially and relatively reduced.

[0031] When environmental changes such as temperature (humidity) changes occur and stress is generated internally, the parts with relatively low adhesive strength will delaminate due to internal stress, while the connection part of the cathode electrode layer can be spared from the effects of internal stress. Therefore, solid electrolytic capacitors having this structure have increased resistance to environmental changes.

[0032] 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. These layers can also be constructed without glass cloth.

[0033] The solid electrolytic capacitor element and the second side electrode E2 are connected at multiple positions along the Z-axis. The first connection point S14 is where the side surface of the upper cathode electrode layer 14 and the second side electrode E2 come into contact and are electrically connected. The second connection point S14B is where the side surface of the lower cathode electrode layer 14B and the second side electrode E2 come into contact and are electrically connected. In the first example, the insulating part 30 consists only of a resin that does not contain fillers (e.g., epoxy resin). The adhesion strength of the connection point S30 between the insulating part 30 and the second side electrode E2 is set to be lower than that near the cathode electrode layer. When the temperature (humidity) is increased, the connection point S30 breaks down and becomes disconnected before the cathode electrode layer becomes disconnected. Even in such cases, the solid electrolytic capacitor can still operate, thus providing high resistance to environmental changes.

[0034] At each of these connection points, the strength that prevents the joined or bonded elements from physically separating is defined as the adhesion strength. That is, when a solid electrolytic capacitor is heated, thermal expansion causes stress to be applied to each element in the thickness direction and in-plane direction. The greater the stress that causes the connected elements to physically separate, the higher the adhesion strength. Each connection point has shear strength, peel strength, and tensile strength, but here, the strength that suppresses the resulting disconnection state is expressed as adhesion strength. The term connection strength may be used instead of adhesion strength.

[0035] In the solid electrolytic capacitor of this example, the following adhesion strength can be set to increase resistance to environmental changes.

[0036] In Figure 3, the upper intermediate layer connection portion S20 is the portion where the side surface of the upper intermediate layer 20 and the second side electrode E2 come into contact and are bonded together. The upper first protective layer connection portion S15 is the portion where the side surface of the upper first protective layer 15 and the second side electrode E2 come into contact and are bonded together. The upper first insulating layer connection portion S11 is the portion where the side surface of the upper first insulating layer 11 and the second side electrode E2 come into contact and are bonded together.

[0037] Similarly, the lower intermediate layer connection portion S20 in Figure 3 is the portion where the side surface of the lower intermediate layer 20 and the second side electrode E2 come into contact and are bonded together. The lower second protective layer connection portion S15B is the portion where the side surface of the lower second protective layer 15B and the second side electrode E2 come into contact and are bonded together. The lower second insulating layer connection portion S11B is the portion where the side surface of the lower second insulating layer 11B and the second side electrode E2 come into contact and are bonded together.

[0038] To increase the adhesion strength near the connection point between the upper cathode electrode layer 14 and the lower cathode electrode layer 14B, the layers adjacent to each cathode electrode layer (first insulating layer 11, first protective layer 15, upper intermediate layer 20, second insulating layer 11B, second protective layer 15B, lower intermediate layer 20) contain resin and filler, thereby increasing the adhesion strength at each connection point. Furthermore, the adhesion strength at these connection points can be set higher than the adhesion strength at the insulating portion 30.

[0039] The first insulating layer 11 and the second insulating layer 11B each contain a resin and a filler, respectively, to enhance the adhesion strength near the cathode electrode layer.

[0040] As a result, the disconnection of the connection area near the cathode electrode layer can be suppressed, at the expense of damage in the insulating portion 30.

[0041] Next, we will provide a more detailed explanation of the materials and structure of each element.

[0042] 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.

[0043] 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).

[0044] 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 serves to prevent the diffusion of Sn and other metals contained in the solder and the third electrode layer, and to prevent oxidation of Cu and other metals contained in the first electrode layer. As the material for the second electrode layer E22, materials such as Ni, which are more resistant to oxidation than Cu and inhibit metal diffusion, can be used. If the second electrode layer E22 is too thin, its oxidation and diffusion prevention effects will be weakened, and if it is too thick, the resistance will increase. A suitable example thickness for the second electrode layer E22 is 1 μm to 5 μm, and a more suitable 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 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.

[0045] 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 (e.g., an alloy of Sn or SnAg). A preferred example thickness of the third electrode layer E23 is 3 μm to 7 μm, and a more preferred example thickness 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.

[0046] Furthermore, the structure and material of the first side electrode E1 may be the same as that of the second side electrode E2. The structure and material of the first side electrode E1 and the second side electrode E2 may also be different.

[0047] 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.

[0048] 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.

[0049] 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 the error component, 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 position Z14B at the interface between the second insulating layer 11B and the lower cathode electrode layer 14B, and position Z11B.

[0050] When the filler content is high and the thickness is large, the adhesion strength at the connection point can be increased. Therefore, when the above relationship exists, the adhesion strength of the connection point near the cathode electrode layer becomes relatively higher, and disconnection of the connection point can be further suppressed.

[0051] Furthermore, it is preferable that A1, M1, and M2 have the following relationships.

[0052] A1 can be set to 1 μm ≤ A1 ≤ 300 μm. Preferably, A1 can be set to 10 μm ≤ A1 ≤ 110 μm. M1 can be set to 1 μm ≤ M1 ≤ 100 μm. Preferably, M1 can be set to 20 μm ≤ M1 ≤ 60 μm. M2 can be set to 1 μm ≤ M2 ≤ 100 μm. Preferably, M2 can be set to 20 μm ≤ M2 ≤ 60 μm.

[0053] Environmental testing of solid electrolytic capacitors revealed that they exhibit increased resistance to current-conducting tests in high-humidity environments at the connection points of the cathode electrode layer.

[0054] Further explanation will be provided regarding the materials and other components of each element that make up a solid electrolytic capacitor.

[0055] The number of solid electrolytic capacitor elements CE shown in Figure 1 is assumed to be four. The thickness of each element in the laminate 100 is the dimension of each element in the lamination direction (Z-axis direction). The intermediate layer 20, the uppermost layer 20TOP, and the bottommost layer 20BTM can each be prepregs containing a thermosetting resin such as epoxy resin and further containing glass cloth. The glass cloth can be a plain weave glass cloth, and the fibers constituting the glass cloth extend along the X-axis and Y-axis directions.

[0056] The protective insulator 16 is made of an insulating material. Inorganic insulating materials and organic insulating materials are known as insulating materials.

[0057] Examples of inorganic insulating materials include silicon oxide (e.g., SiO2) and silicon nitride (e.g., SiNx Examples of organic insulating materials include aluminum oxide (e.g., Al2O3) and magnesium oxide (e.g., MgO). Thermosetting resins such as polyimide and epoxy resins are known as organic insulating materials. 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, or film-like.

[0058] 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 may 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-Fired 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.

[0059] 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 materials (Sn) found in solder on its surface. These metallic materials may contain other elements.

[0060] 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 be set in the same way as the material for the first side electrode E1.

[0061] The anode electrode layer 8 shown in Figure 2 contains the first metal (aluminum). The insulating region (10, 10B) and the solid electrolyte layer (12, 12B), which are mixed regions, also contain the first metal (aluminum) as roughened layers.

[0062] The dielectric layer (9,9B) shown in Figure 2 is, exemplarily, made of aluminum oxide. The thickness of the dielectric layer (9,9B) is, for example, 1 nm to 1 μm.

[0063] 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 mixtures of two or more. These materials can be given excellent conductivity by adding appropriate dopants.

[0064] 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.

[0065] The metallic conductive layer constituting the cathode electrode layer (14, 14B) can be made of copper (Cu), nickel (Ni), silver (Ag), or tin (Sn), etc., 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 made of 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 electroplating method.

[0066] 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.

[0067] 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, fillers generally do not penetrate the insulating region (10, 10B). Therefore, the filler content in the insulating region (10, 10B) is lower than the filler content in the insulating layer (11, 11B).

[0068] 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, fillers such as silica (silicon oxide) can be used. As the resin material, polyimide or thermosetting resins such as epoxy resin can be used. In this example, a protective layer (15, 15B) with silica added to epoxy resin is used. The resist material can be a liquid material dissolved in a suitable solvent during manufacturing. Note that the protective layer (15, 15B) may be omitted.

[0069] 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.

[0070] The insulating portion 30 may include material A, which is a resist material containing a resin, or material B, which contains a resin and an inorganic filler. A thermosetting resin such as epoxy resin can be used as the resin material. As an example of material B, an epoxy resin containing silica filler can be used. Examples of such resins include phenolic resin, methacrylic resin, epoxy resin, silicon resin, polycarbonate, polyethylene terephthalate, polyamide, polyimide, polybutadiene, polyethylene, and polystyrene. Examples of inorganic materials constituting the filler include silica (SiO2), aluminum oxide (Al2O3), and aluminum nitride (AlN).

[0071] FIG. 4 is an enlarged view of a vicinity region of a second side electrode in a solid electrolytic capacitor element (second example).

[0072] The solid electrolytic capacitor element of this example is different in that the insulating portion 30 has a three-layer structure as compared with that shown in FIG. 3, and other configurations are the same as those shown in FIG. 3.

[0073] In the second example, the third connection site S30U is a site where the side surface of the upper layer 30U and the second side electrode E2 are in contact with and adhered to each other and connected. The fourth connection site S30M is a site where the side surface of the middle layer 30M and the second side electrode E2 are in contact with and adhered to each other and connected. The fifth connection site S30D is a site where the side surface of the lower layer 30D and the second side electrode E2 are in contact with and adhered to each other and connected.

[0074] The adhesion strength IC(14) at the first connection site S14 and the adhesion strength IC(14B) at the second connection site S14B are substantially the same (IC(14) ≈ IC(14B)). Substantially the same can include an error of 30%. The adhesion strength IC(30U) of the third connection site S30U, the adhesion strength IC(30M) of the fourth connection site S30M, and the adhesion strength IC(30D) of the fifth connection site S30D are each smaller than the adhesion strengths IC(14) and IC(14B) of the cathode electrode layer (IC(30U) < IC(14), IC(30M) < IC(14), IC(30D) < IC(14)). When a heating test is performed, these adhesion strengths can also be expressed by the temperature at which they become non-connected states. Even when the solid electrolytic capacitor is heated and the third connection site S30U, the fourth connection site S30M, or the fifth connection site S30D becomes a non-connected state, the first connection site S14 and the second connection site S14B can maintain the connected state. That is, the solid electrolytic capacitor can operate and has high resistance to environmental changes.

[0075] In this example, the adhesion strength IC (30M) of the middle layer 30M is higher than that of the adhesion strength IC (30U) and IC (30D) of the upper layer 30U and the lower layer 30D (IC (30U) < IC (30M), IC (30D) < IC (30M)). The filler content rate of the middle layer 30M is higher than that of the upper layer 30U and the lower layer 30D, and the adhesion strength is also higher.

[0076] In order to increase the adhesion strength in the vicinity of the connection part of the upper cathode electrode layer 14 and the lower cathode electrode layer 14B, the layers adjacent to each cathode electrode layer (the first insulating layer 11, the first protective layer 15, the upper intermediate layer 20, the second insulating layer 11B, the second protective layer 15B, the lower intermediate layer 20) are set to contain resin and filler, so as to increase the adhesion strength at each connection part. The adhesion strength of these connection parts can be set higher than that of the upper layer 30U and the lower layer 30D in the insulating part 30.

[0077] The insulating part 30 includes an upper layer 30U (the first resin layer) located on the side of the first insulating layer 11, a lower layer 30D (the second resin layer) located on the side of the second insulating layer 11B, and an intermediate layer 30M (the intermediate resin layer) interposed between the upper layer 30U (the first resin layer) and the lower layer 30D (the second resin layer) and having a filler content rate higher than that of either the upper layer 30U (the first resin layer) or the lower layer 30D (the second resin layer). In the insulating part 30, since the adhesion strength of the middle layer 30M is partially high, large destruction of the insulating part 30 can be suppressed, and further disconnection of the connection part in the cathode electrode layer can be suppressed.

[0078] Note that 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. The thickness Z1 (μm) of the first insulating layer 11, the thickness Z2 (μm) of the second insulating layer 11B, the thickness M1 (μm) of the upper layer 30U (the first resin layer), the thickness M2 (μm) of the lower layer 30D (the second resin layer), the thickness A1 (μm) of the middle layer 30M (the intermediate resin layer), the filler content rate C Z1 (mass%) in the first insulating layer 11, the filler content rate C 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. C M1 < C Z1 , C M2 < C Z2 , C M1 < C A1 , C M2 < C A1 . Thereby, as described later, the environmental resistance of the solid electrolytic capacitor is increased. Also, Z1 < M1, Z2 < M2, and A1 < M1 can be satisfied.

[0079] In the fixed electrolytic capacitor, C Z1 ≤ C A1、 C Z2 ≤ C A1 can be satisfied, and when the third connection site S30U and the fifth connection site S30D are broken, stress is applied from both the upper and lower directions to the fourth connection site S30M. Therefore, by increasing the filler content C A1 , the adhesion of the fourth connection site S30M is improved, and there is an effect that breakage at the fourth connection site S30M becomes less likely to occur. Note that as long as the effect of suppressing non-connection of the connection site in the cathode electrode layer is not impaired, C A1 < C Z1 , C A1 < C Z2 may be satisfied.

[0080] The insulating portion 30 includes a constituent material (referred to as material A) included in the upper insulating region 10 and the lower insulating region 10B at least in the upper layer and the lower layer. The middle layer 30M of the insulating portion 30 mainly includes 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.

[0081] Material A consists of a resist material containing a resin, 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.

[0082] 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, for example, have a low filler content. The middle layer 30M of the insulating part 30 mainly contains material B, and contains epoxy resin and filler, and, for example, has a higher filler content than 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, and polystyrene. Examples of inorganic materials constituting the filler include silica (SiO2), aluminum oxide (Al2O3), and aluminum nitride (AlN).

[0083] Next, we will explain the advantages of the first and second examples of fixed electrolytic capacitor elements compared to the comparative examples described above.

[0084] Figure 5 schematically shows the vicinity region of the second side electrode of the fixed electrolytic capacitor element in the first example (Figure 5(A)), the second example (Figure 5(B)), and the comparative example (Figure 5(C)).

[0085] As shown in Figure 5(A), the insulating part 30 of the first example has a single-layer structure, and the single-layer structure consists only of a resin, such as epoxy resin. The insulating part 30 can also contain resin and a small amount of filler. When the temperature (humidity) is increased, the connection part S30 breaks down and the connection becomes disconnected before the cathode electrode layer (14, 14B) and the second side electrode E2 separate and become disconnected. More specifically, when the second side electrode E2 expands due to heat, the connection part S30 peels off from the insulating part 30, a gap is formed between them, and the stress near the cathode electrode layer (14, 14B) is relieved.

[0086] As shown in Figure 5(B), the insulating part 30 of the second example has a three-layer structure, comprising an upper layer 30U made only of resin, a middle layer 30M containing resin and filler, and a lower layer 30D made only of resin. Since the adhesive strength of the middle layer 30M is higher than that of either the upper layer 30U or the lower layer 30D, the middle layer 30M does not peel off from the second side electrode E2. On the other hand, the upper layer 30U and the lower layer 30D peel off from the second side electrode E2 due to thermal expansion. That is, when the temperature (humidity) is increased, the connection parts (S30U, S30D) break down and become disconnected before the cathode electrode layers (14, 14B) and the second side electrode E2 separate and become disconnected. More specifically, when the second side electrode E2 undergoes thermal expansion, it peels away from the insulating portion 30 at these connection points (S30U, S30D), creating a gap between them and relieving stress near the cathode electrode layer (14, 14B).

[0087] As shown in Figure 5(C), the insulating portion 30 of the comparative example has a single-layer structure, and this single-layer structure contains resin and filler. An example of the filler content of the insulating portion 30 in the comparative example is the same as the filler content of the middle layer 30M in the second example. Filler content C in the insulating portion 30 of the comparative example and the middle layer 30M of the second example. A1 40 (mass%) ≤ C A1 The value is ≤90 (mass%). The filler content in the insulating part 30 of the first example is set lower than the lower limit of the filler content in the insulating part 30 of the comparative example (0 (mass%) ≤ C A1It can be ≤30 (mass%).

[0088] The insulating portion 30 in the first example has a single-layer structure, and the insulating portion 30 in the second example has a three-layer structure. However, the insulating portion 30 is not limited to these structures as long as it has a portion with a lower filler content than the insulating layer (11, 11B) at the connection point between the insulating portion 30 and the second side electrode E2. Because the insulating portion 30 has a portion with a lower filler content than the insulating layer (11, 11B) at the connection point with the second side electrode E2, the portion in question is destroyed and becomes disconnected before the cathode electrode layer (14, 14B) and the second side electrode E2 separate and become disconnected due to environmental changes such as thermal expansion.

[0089] Next, we will briefly explain the manufacturing method of solid electrolytic capacitors.

[0090] 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 parts 30, and these areas are filled with the same material as the insulating areas (10, 10B). The manufacturing method of the solid electrolytic capacitor sheet comprises (a) a metal sheet preparation step, (b) an insulating area 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.

[0091] (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. 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.

[0092] (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 form the 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 the 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.

[0093] In the first example, when forming the insulating region (10,10B), a protective film is applied in advance to the surface area of ​​the roughened layer adjacent to the region to be formed by the second side electrode E2, if necessary. After the protective film is formed, the resist is applied to form the insulating region. The protective film can be made of a resist with high viscosity, high filler content, and low penetration into the roughened layer. As a result, an insulating region is not formed directly beneath the resist, the state of the roughened layer is maintained, and in the subsequent etching process in the groove, the roughened layer in that area is etched, and insulating material is filled into the etched area to form the insulating portion 30. In the second example, when forming the insulating region (10,10B), prior formation of a protective film is not necessary, and during etching in the groove, the upper and lower regions of the region to be formed of the insulating portion 30 are made of insulating regions formed by resin seeping into the roughened layer.

[0094] (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 a 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.

[0095] (d) In the conductive layer formation step, 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 formation method, 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.

[0096] (e) In the cathode electrode layer formation process, 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, 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 top of the underlayer. In this example, the material of the plating layer is copper (Cu).

[0097] (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.

[0098] (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.

[0099] Next, multiple solid electrolytic capacitor sheets are stacked on the bottom layer 20BTM, which serves as a support substrate as shown in Figure 1. Adhesive insulating layers (20), as shown in the same figure, are placed between each sheet, between the sheets and the support substrate, and on the top sheet. These sheets are bonded together to produce a laminated sheet. A rotating blade is applied to the laminated sheet to form grooves along the Y-axis direction, with the negative Z-axis direction being the depth direction. Similarly, a rotating blade is applied to the laminated sheet to form grooves along the X-axis direction, with the negative Z-axis direction being the depth direction. An etching solution is introduced into the formed grooves 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.

[0100] 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 portion 30. In the first example, the insulating portion 30 consists of a single layer uniformly filled with insulating material. In the second example, in the etching process in the groove, the etching of the upper and lower layers of the area where the insulating portion is to be formed is not complete, and an insulating area made of low-density resin remains in that area, so a three-layer insulating portion 30 is formed. 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 groove and space. The form of the supplied insulating resin may be liquid or in the form of a 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.

[0101] 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.

[0102] The aforementioned solid electrolytic capacitors were manufactured and their environmental resistance was evaluated.

[0103] The first and second examples of solid electrolytic capacitors described above are equipped with a second mixing region (40, 40B), which increases the adhesive strength of that region and improves environmental resistance to temperature (humidity) changes, etc. Environmental tests conducted on the first and second examples of solid electrolytic capacitors confirmed that the presence of the second mixing region (40, 40B) enhances the environmental resistance of the solid electrolytic capacitors. Further details are provided below.

[0104] (Experimental conditions) First, although Figure 1 shows two solid electrolytic capacitor elements CE, 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 silica glass mainly composed of SiO2. The silica glass used as an example is E glass. Note that silica-containing glass such as NE glass, or other known glass can be used as the filament material.

[0105] The top layer 20TOP and the bottom layer 20BTM contain resin and glass cloth. This resin is epoxy resin. This glass cloth has a plain weave structure composed of multiple glass threads, and the thicknesses of the top layer 20TOP and the bottom layer 20BTM are 150 μm and 200 μm, respectively. The intermediate layer (20) contains epoxy resin and glass cloth and has a thickness of 30 μm.

[0106] In the basic solid electrolytic capacitor structure, the anode electrode layer 8 included in the solid electrolytic capacitor element is 25 μm thick aluminum, the dielectric layers (9, 9B) are aluminum oxide, and the solid electrolyte layers (12, 12B) are 50 μm thick roughened aluminum layers impregnated with PEDOT. The thickness of the anode electrode layer 8 is matched to the thickness of the middle layer (intermediate insulating layer (30)) if the insulating part 30 has a three-layer structure.

[0107] 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 1 to 20 μm, and the protective layer 15 is made of silica filler-containing epoxy resin with a thickness of 20 μm (filler content = 40 (mass%)).

[0108] The insulating regions (10, 10B) consist of an aluminum roughening layer with a thickness of 50 μm containing epoxy resin, while the insulating layers (11, 11B) consist of a silica filler-containing epoxy resin with a thickness of 5 to 30 μm (filler content = 50 to 80 (mass%)). If the insulating section 30 has a single-layer structure, it consists of an epoxy resin with a thickness of 50 to 300 μm and a filler content of 0 to 80 (mass%). If the insulating section 30 has a three-layer structure, the upper and lower layers consist of epoxy resin with a thickness of 15 to 125 μm, respectively, and the middle layer of the insulating section 30 consists of a filler-containing epoxy resin with a thickness of 20 to 200 μm (filler content = 0 to 80 (mass%)).

[0109] 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.

[0110] 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 with the negative Z-axis direction as the depth direction are formed in this laminated sheet by applying a rotating blade to the laminate. 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 with four layers of solid electrolytic capacitor elements covered with a protective insulator is completed. (Evaluation and Results)

[0111] Figure 6 is a chart showing the parameters and evaluation results for each element in the first example.

[0112] The figure shows, for a solid electrolytic capacitor including the structure of the first example (Figure 3), the thickness of the first cathode electrode layer 14 (ZC1 (μm)) (thickness of the second cathode electrode layer 14B ZC2 (μm)), the thickness of the first insulating layer 11 (Z1 (μm)) (thickness of the second insulating layer 11B (Z2 (μm))), and the filler content of the first insulating layer (C Z1 (Mass %) (Filler content of the second insulating layer (C) Z2 (mass%), thickness of insulating part 30 (Z0 (μm)), and filler content (C M0The values ​​(mass %) are shown. The environmental resistance of the solid electrolytic capacitor was evaluated by performing a humidity resistance and electrical current test. The thickness of each layer was determined by observation using an optical microscope. If the surface of each layer was rough and uneven, the thickness was determined using the average height position obtained by the least squares method. The filler content was determined by sampling each layer, heating it in an electric furnace at 600°C for 1 hour in an air atmosphere to ash the resin components, and extracting only the filler. The weight before and after the treatment was measured with an electronic balance, and the filler content was calculated from the weight ratio.

[0113] (Humidity Resistance Test): In the humidity resistance test, the rated voltage (2.5V) was applied for 2000 hours under conditions of 85°C and 85%RH humidity.

[0114] The tested products were impregnated with embedding resin and then cured. They were then polished with waterproof abrasive paper to expose the cross-section. The presence or absence of a break between the second side electrode and the cathode electrode layer was observed using an optical microscope at 100x magnification. A moisture resistance and electrical conductivity test was performed on n products (n=11) each possessing one attribute parameter.

[0115] (Evaluation S): If the number of products found to have broken wires is 0, this solid electrolytic capacitor is evaluated as (Evaluation S) in the moisture resistance and power conduction test.

[0116] (Evaluation A): If only one product is found to have a broken wire, this solid electrolytic capacitor is evaluated as (Evaluation A) in the moisture resistance and electrical conductivity test.

[0117] (Evaluation B): If two products are found to have broken wires, this solid electrolytic capacitor is evaluated as (Evaluation B) in the moisture resistance and power conduction test.

[0118] (Evaluation C): If 3 to 5 products are found to have broken wires, this solid electrolytic capacitor will be evaluated as (Evaluation C) in the humidity resistance and power supply test. Products with (Evaluation C) can be used unless the operating environment is severe. An operating environment that is not severe is, for example, when the humidity resistance test duration is 1000 hours and the humidity resistance test temperature is 60°C in the above test.

[0119] (Evaluation D): If more than 5 products are found to have broken wires, this solid electrolytic capacitor will be evaluated as (Evaluation D) in the moisture resistance and power supply test. Products with (Evaluation D) are defective.

[0120] The experimental examples Data 5, Data 7, Data 13, Data 18, Data 19, and Data 21 yielded results of (Evaluation S) or (Evaluation A). In all of these experimental examples, the filler content of the insulating part 30 was 0 (mass%). In (Evaluation S), the thickness of the cathode electrode layer (14, 14B) was greater than the thickness of the cathode electrode layer in (Evaluation A).

[0121] Regarding the data for (Evaluation S) or (Evaluation A), the filler content C of the insulating part. M0 (Mass %) represents the filler content (C) of the insulating layer (11,11B). Z1 (mass%), C Z2 It is smaller than (mass%). In other words, the adhesive strength of the insulating part 30 near the side electrode is lower than that of the insulating layer and the cathode electrode layer located nearby, and peeling is performed when the environmental burden is high to suppress peeling of the cathode electrode layer. The data for (Evaluation B) and (Evaluation C) also have this relationship with the filler content.

[0122] In other words, considering the data from (Evaluation S) to (Evaluation C), the filler content C in the first insulating layer 11 Z1 (mass%), filler content C in the second insulating layer 11B Z2 (mass%), and filler content C in the insulating part 30 M0 (mass%) is C M0 <C Z1 , C M0 <C Z2The relationship is satisfied. On the other hand, the data with evaluation D does not satisfy these relationships.

[0123] (Evaluation A) Data: Filler content C in the insulating part M0 As the (mass %) increases, the evaluation rank decreases to (Evaluation B) and (Evaluation C), as shown in Data 2-4. Filler content C of the insulating part M0 (mass%) and filler content in the insulating layer (C Z1 (mass%), C Z2 When the difference from (mass%) becomes 0 (mass%), a result of (Evaluation D) is obtained.

[0124] Regarding the thickness of the cathode electrode layer, the evaluation rank tends to decrease as the thickness decreases. This is thought to be because the adhesion area between the cathode electrode layer and the second side electrode becomes smaller, making it easier to peel off. If the relationship of filler content in data of (evaluation C) or higher is satisfied, the thickness of each cathode insulating layer (ZC1(μm), ZC2(μm)) can be further set to 1(μm)≦ZC1(μm)≦20(μm) and 1(μm)≦ZC2(μm)≦20(μm). Preferably, it can be set to 3(μm)≦ZC1(μm)≦20(μm) and 3(μm)≦ZC2(μm)≦20(μm). Preferably, it can be set to 5(μm)≦ZC1(μm)≦20(μm) and 5(μm)≦ZC2(μm)≦20(μm). Preferably, the limits can be set to 10(μm) ≤ ZC1(μm) ≤ 20(μm) and 10(μm) ≤ ZC2(μm) ≤ 20(μm). The upper limit can be increased further, but from the standpoint of material costs, etc., having the necessary thickness is sufficient.

[0125] Figures 7 and 8 are charts showing the parameters and evaluation results for each element in the second example.

[0126] The figure shows a solid electrolytic capacitor including the structure of the second example (Figure 4), with the above-mentioned ZC1(μm)(ZC2(μm)), Z1(μm)(Z2(μm)), (C Z1 (mass%)(C Z2In addition to (mass%), the thickness of the first resin layer (30U) (M1 (μm)) and the filler content (C) must also be specified. M1 (Mass %) (Thickness of the second resin layer (30D) (M2 (μm)) and filler content (C M2 The percentage (by mass) is shown. The environmental resistance of the solid electrolytic capacitor was evaluated by performing a humidity resistance and electrical current test.

[0127] The method for assigning the evaluation ranking (rating S to rating D) is the same as described above.

[0128] The experimental examples that received a (Rating S) or (Rating A) result were data 16-22, data 28-32, data 38, data 40, data 43, and data 45. These experimental examples were at least C M1 <C Z1 , C M2 <C Z2 , C M ≤C A1 , C M2 ≤C A1 The following relationship is satisfied. Filler content (C) of the first and second resin layers. M1 , C M2 ) is the filler content (C) in the intermediate resin layer (30M). A1 If the amount is less than (C), the adhesive strength between the first and second resin layers and the second side electrode becomes relatively small, and if the environmental burden is high, peeling or other measures are taken to suppress peeling of the cathode electrode layer. In addition, the filler content (C) in the first insulating layer 11 and the second insulating layer 11B located near the cathode electrode layer is also reduced. Z1 , C Z2 ) is the filler content (C) of the first and second resin layers in the insulating part. M1 , C M2 The results are higher than those for (Evaluation B) and (Evaluation C), and peeling of the cathode electrode layer is relatively suppressed. The data for (Evaluation B) and (Evaluation C) also have these relationships with filler content. On the other hand, the data from which the result for (Evaluation D) is obtained does not satisfy these relationships.

[0129] Increasing the filler content of the first and second insulating layers (30U, 30D) in the insulating section 30 tends to lower the evaluation ranking. It is thought that the greater the thickness of the cathode electrode layer (ZC1, ZC2), the less likely the cathode electrode layer is to peel off. The thickness of each cathode insulating layer (ZC1(μm), ZC2(μm)) can be set to 1(μm)≦ZC1(μm)≦20(μm) and 1(μm)≦ZC2(μm)≦20(μm). Preferably, it can be set to 3(μm)≦ZC1(μm)≦20(μm) and 3(μm)≦ZC2(μm)≦20(μm). Preferably, it can be set to 5(μm)≦ZC1(μm)≦20(μm) and 5(μm)≦ZC2(μm)≦20(μm). Preferably, the limits can be set to 10(μm) ≤ ZC1(μm) ≤ 20(μm) and 10(μm) ≤ ZC2(μm) ≤ 20(μm). The upper limit can be increased further, but from the standpoint of material costs, etc., having the necessary thickness is sufficient.

[0130] 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 min The error can be set to ) × R%, with R=10, or to 20, 30, or 40. Furthermore, if any parameter P is a specific numerical value, its error range can be set to P × 95% ≤ P ≤ P × 105%.

[0131] As described above, the solid electrolytic capacitor of the first aspect includes a first solid electrolyte layer 12 disposed between the anode electrode layer 8 and the first cathode electrode layer 14, a second solid electrolyte layer 12B disposed between the anode electrode layer 8 and the second cathode electrode layer 14B, a first side electrode E1 contacting the first side surface 81 of the anode electrode layer 8, a second side electrode E2 contacting the side surfaces of the first cathode electrode layer 14 and the second cathode electrode layer, an insulating portion containing resin interposed between the second side surface of the anode electrode layer and the second side electrode, a first insulating layer containing resin and filler interposed between the first cathode electrode layer and the insulating portion, and a second insulating layer containing resin and filler interposed between the second cathode electrode layer and the insulating portion. The filler content C Z1 (mass%) in the first insulating layer, the filler content C Z2 (mass%) in the second insulating layer, and the filler content C M0 (mass%) in the insulating portion satisfy C M0 <C Z1 , C M0 <C Z2 .

[0132] The solid electrolytic capacitor of the second aspect includes a first solid electrolyte layer disposed between the anode electrode layer and the first cathode electrode layer, a second solid electrolyte layer disposed between the anode electrode layer and the second cathode electrode layer, a first side electrode contacting the first side surface of the anode electrode layer, a second side electrode contacting the side surfaces of the first cathode electrode layer and the second cathode electrode layer, an insulating portion containing resin interposed between the second side surface of the anode electrode layer and the second side electrode, a first insulating layer containing resin and filler interposed between the first cathode electrode layer and the insulating portion, and a second insulating layer containing resin and filler interposed between the second cathode electrode layer and the insulating portion. The insulating portion includes a first resin layer located on the first insulating layer side, a second resin layer located on the second insulating layer side, and an intermediate resin layer interposed between the first resin layer and the second resin layer and having a filler content higher than that of either the first resin layer or the second resin layer. The filler content C Z1 (mass%) in the first insulating layer, the filler content C Z2 (mass%) in the second insulating layer, the filler content C M1 (mass%) in the first resin layer, the filler content C M2(mass%), and filler content C in the intermediate resin layer A1 (mass%) is C M1 <C Z1 , C M2 <C Z2 , C M <C A1 , C M <C A1 It satisfies the condition.

[0133] 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. [Explanation of Symbols]

[0134] 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... Insulation 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 first solid electrolyte layer is placed between the anode electrode layer and the first cathode electrode layer, A second solid electrolyte layer is disposed between the anode electrode layer and the second cathode electrode layer, A first side electrode in contact with the first side surface of the anode electrode layer, A second side electrode in contact with the side surface of the first cathode electrode layer and the side surface of the second cathode electrode layer, An insulating portion containing resin is interposed between the second side surface of the anode electrode layer and the second side electrode, A first insulating layer comprising a resin and filler is interposed between the first cathode electrode layer and the insulating portion, A second insulating layer containing resin and filler is interposed between the second cathode electrode layer and the insulating portion, Equipped with, Filler content C in the first insulating layer Ｚ１ (mass%), Filler content C in the second insulating layer Ｚ２ (mass%), and, Filler content C in the insulating portion Ｍ０ (Mass %) is, C Ｍ０ <C Ｚ１ 、C Ｍ０ <C Ｚ２ A solid electrolytic capacitor that satisfies the following conditions.

2. A first solid electrolyte layer is placed between the anode electrode layer and the first cathode electrode layer, A second solid electrolyte layer is disposed between the anode electrode layer and the second cathode electrode layer, A first side electrode in contact with the first side surface of the anode electrode layer, A second side electrode in contact with the side surface of the first cathode electrode layer and the side surface of the second cathode electrode layer, An insulating portion containing resin is interposed between the second side surface of the anode electrode layer and the second side electrode, A first insulating layer comprising a resin and filler is interposed between the first cathode electrode layer and the insulating portion, A second insulating layer containing resin and filler is interposed between the second cathode electrode layer and the insulating portion, Equipped with, The insulating portion is The first resin layer located on the side of the first insulating layer, The second resin layer located on the side of the second insulating layer, An intermediate resin layer interposed between the first resin layer and the second resin layer, having a higher filler content than either the first resin layer or the second resin layer, Equipped with, Filler content C in the first insulating layer Ｚ１ (mass%), The filler content C in the second insulating layer Ｚ２ (mass %), Filler content C in the first resin layer Ｍ１ (mass%), Filler content C in the second resin layer Ｍ２ (mass%), and, Filler content C in the intermediate resin layer Ａ１ (Mass %) is, C Ｍ１ <C Ｚ１ 、C Ｍ２ <C Ｚ２ 、C Ｍ１ <C Ａ１ 、C Ｍ２ <C Ａ１ A solid electrolytic capacitor that satisfies the following conditions.

3. C Ｚ１ ≤ C Ａ１ , C Ｚ２ ≤ C Ａ１ Satisfying The solid electrolytic capacitor according to claim 2.

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