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 solid electrolyte layer 12 disposed between an anode electrode layer 8 and a cathode electrode layer (14, 14B), a first side electrode E1 in contact with the side surface of the anode electrode layer 8, a second side electrode E2 in contact with the side surface of the cathode electrode layer (14, 14B), an insulating region (10, 10B) disposed on the side of the first side electrode E1 on the anode electrode layer 8 and containing a first metal and a first resin, and a mixed region (40, 40B) disposed between the first side electrode E1 and a first mixed region and containing a second metal different from the first metal and a first resin.

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 Initiative] [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 solid electrolytic capacitor of this disclosure comprises a solid electrolyte layer disposed between an anode electrode layer and a cathode electrode layer; a first side electrode in contact with the side surface of the anode electrode layer; a second side electrode in contact with the side surface of the cathode electrode layer; a first mixed region disposed on the first side electrode side of the anode electrode layer and containing a first metal and a first resin; and a second mixed region disposed between the first side electrode and the first mixed region and containing a second metal different from the first metal and a first resin. [Effects of the Invention]

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

[0007] [Figure 1] Figure 1 shows the longitudinal cross-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 first region within the solid electrolytic capacitor element of the first example. [Figure 4] Figure 4 is a diagram illustrating the detailed structure within the first region in the first example. [Figure 5] Figure 5 is an enlarged view of the first region related to the second example. [Figure 6] Figure 6 is a diagram illustrating the detailed structure within the first region in the second example. [Figure 7] Figure 7 is a chart showing the experimental data. [Figure 8] Figure 8 is a chart showing the experimental data. [Figure 9] Figure 9 is a chart showing the experimental data. [Figure 10] Figure 10 is a chart showing the experimental data. [Figure 11] Figure 11 is a chart showing the experimental data. [Figure 12] Figure 12 is a chart showing the experimental data. [Modes for carrying out the invention]

[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 includes a lowermost layer 20BTM as a support substrate, a laminate 100 including the support substrate, and a protective insulator 16 provided on the top surface and the side surface where no electrode is formed of the laminate 100. An anode terminal 1 and a cathode terminal 2 are provided on the lower surface of the support substrate. A first side surface electrode E1 electrically connected to the anode terminal 1 is provided on a first side surface S1 of the laminate 100. A second side surface electrode E2 electrically connected to the cathode terminal 2 is provided on a second side surface S2 of the laminate 100.

[0011] A three-dimensional orthogonal coordinate system is set. The stacking direction of the solid electrolytic capacitor element 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 surface electrode E1 to the second side surface electrode E2. The Y-axis is perpendicular to the Z-axis and also perpendicular to 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 includes a plurality of solid electrolytic capacitor elements CE and a plurality of insulating layers (20). The plurality of insulating layers (20) include a lowermost layer 20BTM (20), an uppermost layer 20TOP (20), and one or more intermediate layers 20.

[0013] The lowermost layer 20BTM (20) constitutes the support substrate. The uppermost layer 20TOP is disposed between the protective insulator 16 and the upper solid electrolytic capacitor element CE. The plurality of intermediate layers 20 include an intermediate layer 20 disposed between the lowermost layer 20BTM and the lower solid electrolytic capacitor element, an intermediate layer 20 disposed between solid electrolytic capacitor elements CE adjacent in the thickness direction, and an intermediate layer 20 disposed between the uppermost 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 inner layers from external contaminants. The top layer 20TOP increases the mechanical strength of the solid electrolytic capacitor and also functions as a barrier to protect the inner layers from external contaminants together with the protective insulator 16. By providing the solid electrolytic capacitor with the bottom layer 20BTM and the top layer 20TOP, the stress generated inside the laminate due to environmental changes can be suppressed. Also, by providing the solid electrolytic capacitor with one or more intermediate layers 20, the stress generated inside the laminate due to environmental changes can be further suppressed.

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

[0016] FIG. 2 is a diagram showing a longitudinal sectional configuration of the solid electrolytic capacitor element CE.

[0017] One solid electrolytic capacitor element CE includes an anode electrode layer 8.

[0018] 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 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.

[0019] In the upper region of the anode electrode layer 8, a pair of upper insulating regions 10 are formed as first 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.

[0020] The solid electrolytic capacitor element CE comprises a lower cathode electrode layer 14B and a second solid electrolyte layer 12B positioned between the anode electrode layer 8 and the lower cathode electrode layer 14B in the region below the anode electrode layer 8. 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. A residual conductive polymer layer that did not penetrate into the roughened layer during addition may be formed on the lower surface of the second solid electrolyte layer 12B, 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 first 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 the protective insulator 16, and preferably contains a filler in the resin (e.g., epoxy resin). The insulating portion 30 has a three-layer structure consisting of an upper layer 30U, a middle layer 30M, and a lower layer 30D. The insulating portion 30 may also have a single-layer structure.

[0024] In the upper region on the side of the first side electrode E1, an upper mixing region 40 (second mixing region) is located between the first side electrode E1 and the adjacent upper insulating region 10 (first mixing region). In the lower region on the side of the first side electrode E1, a lower mixing region 40B (second mixing region) is located between the first side electrode E1 and the adjacent lower insulating region 10B (first mixing region).

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

[0027] The second mixed region (40,40B) is located between the first side electrode E1 and the first mixed region (insulating region (10,10B)) and contains a second metal different from the first metal and a first resin. The second metal includes metals contained in the side electrode, such as copper. The first resin is a thermosetting resin such as epoxy resin, as described above.

[0028] Figure 3 is an enlarged view of the first region within the solid electrolytic capacitor element according to the first example. The first region is the area near the first side electrode E1.

[0029] In the upper region of the anode electrode layer 8, the upper insulating region 10 (first mixed region), the first insulating layer 11, and the intermediate layer 20 are sequentially stacked. An upper mixed region 40 (second mixed region) is formed between the upper insulating region 10 and the first side electrode E1. In the lower region of the anode electrode layer 8, the lower insulating region 10B (first mixed region), the second insulating layer 11B, and the intermediate layer 20 are sequentially stacked. A lower mixed region 40B (second mixed region) is formed between the lower insulating region 10B and the first side electrode E1.

[0030] The first side electrode E1 is made of a conductive material. In this example, the first side electrode E1 comprises a first electrode layer E11, a second electrode layer E12, and a third electrode layer E13, but it may also be a single-layer structure.

[0031] The first electrode layer E11 is made of a material with excellent electrical conductivity. A preferred example of the thickness of the first electrode layer E11 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 E11 can be a plating layer containing a material with excellent conductivity, i.e., copper (Cu) or silver (Ag).

[0032] The second electrode layer E12 is an intermediate layer interposed between the first electrode layer E11 and the third electrode layer E13. The second electrode layer E12 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 E12, nickel (Ni), which is more resistant to oxidation than Cu and inhibits metal diffusion, can be used. If the second electrode layer E12 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 for the second electrode layer E12 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 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 E12.

[0033] The third electrode layer E13 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 E13 can be made of a metal with good wettability to the solder material (e.g., alloys such as Sn or SnAg). A preferred example thickness of the third electrode layer E13 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 E13 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.

[0034] Furthermore, the structure and material of the second side electrode E2 may be the same as that of the first side electrode E1. The structure and material of the first side electrode E1 and the second side electrode E2 may also be different.

[0035] The second mixed region (40, 40B) is surrounded within the XZ cross-section by the first electrode layer E11, the first insulating layer (11, 11B), the insulating region (10, 10B), and the anode electrode layer 8, and is a mixture of the metallic material contained in the first electrode layer E11 and the resin material contained in the insulating region (10, 10B).

[0036] Figure 4 is a diagram illustrating the detailed longitudinal section structure within the first region in the first example.

[0037] 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 first 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 first thickness A1 of the anode electrode layer 8.

[0038] The shape of the upper mixing region 40 (second mixing region) in the XZ plane is such that it extends from the first side electrode E1 toward the upper insulating region 10. This is because the metal material (aluminum) contained on the first side electrode side of the upper insulating region 10 was removed by etching, and the same metal material as the first side electrode was impregnated into the area where the metal material was removed and the resin material remained. Due to the etching, the side surface of the anode electrode layer 8 is etched, and in the XZ cross-section, this side surface is slightly recessed in the X-axis direction from the reference position Xo.

[0039] In the upper mixing region 40, the tip position Xm is defined as the position furthest from the reference position Xo along the X-axis. The maximum dimension Xmax in the X-axis direction of the upper mixing region 40 is defined as Xmax = |Xm - Xo|.

[0040] Similarly, the shape of the lower mixing region 40B (second mixing region) in the XZ plane has a shape that extends from the first side electrode E1 toward the lower insulating region 10B. In this example, the maximum dimension Xmax in the X-axis direction of the lower mixing region 40B is assumed to be the same as the maximum dimension Xmax in the X-axis direction of the upper mixing region 40.

[0041] Since the structure above and below the anode electrode layer 8 is basically symmetrical with respect to the anode electrode layer 8 and identical, the thickness of the upper and lower insulating regions (10, 10B) is assumed to be equal to M1. The second thickness M1 of the upper insulating region 10 is defined 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. The thickness M2 of the lower insulating region 10B is the second thickness M1 and is defined 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.

[0042] The first thickness A1, the second thickness M1 (=M2), and the maximum dimension Xmax preferably have the following relationship.

[0043] The first thickness A1 of the anode electrode layer 8 can be set to 1 μm ≤ A1 ≤ 300 μm. A preferred exemplary range for the first thickness A1 is 10 μm ≤ A1 ≤ 110 μm.

[0044] The second thickness M1 of the insulating region (10,10B), which is the first mixed region, can be set to 1 μm ≤ M1 ≤ 100 μm. A preferred example range for the second thickness M1 is 20 μm ≤ M1 ≤ 60 μm. The thickness of each solid electrolyte layer (12,12B) shown in Figure 2 can be set to the second thickness M1 of the insulating region.

[0045] The maximum dimension Xmax along the longitudinal direction (X-axis direction) of the anode electrode layer 8 in the second mixing region (40, 40B) satisfies 1.0 (μm) ≤ β ≤ 5.0 (μm), where β = Xmax / M1 × A1. If β falls below the lower limit, the effect of increasing the adhesive strength between the first side surface S1 of the laminate and the first side electrode E1 decreases. Even if it exceeds the upper limit, a significant increase in adhesive strength cannot be expected, and moisture tends to remain between the first and second mixing regions, leading to product damage due to sudden boiling of water during the reflow process.

[0046] Figure 5 is an enlarged view of the first region in the second example. Figure 6 is a diagram illustrating the detailed structure within the first region in the second example.

[0047] The difference between the structure of the second example and the structure of the first example shown in Figures 3 and 4 is that the second example includes an upper third mixing region 50 between the upper insulating region 10 and the upper mixing region 40, and a lower third mixing region 50B between the lower insulating region 10B and the lower mixing region 40B. The other structural features of the second example are the same as those of the first example.

[0048] In the first example structure, the interface between the first mixed region (10, 10B) and the second mixed region (40, 40B) has three-dimensional irregularities and a large contact area. This three-dimensional structure is more complex than the structure at the contact interface between the end face of the aluminum core (anodic electrode layer 8) and the first side electrode E1, and its contact area is also larger. Such a structure is useful for increasing adhesive strength. On the other hand, solid electrolytic capacitors are subjected to heat during manufacturing or when mounted on a substrate. Solid electrolytic capacitors may also be placed in high-humidity environments. In high-temperature, high-humidity environments, the Kirkendall effect occurs, where the first and second metals diffuse from each other, causing the second metal to move within the region where it should originally be located and disappear from that region.

[0049] Therefore, in the structure of the second example, a diffusion suppression region for the metal material is provided. That is, a third mixing region (50, 50B) is provided between the first mixing regions (10, 10B) and the second mixing regions (40, 40B). The third mixing region (50, 50B) is a diffusion suppression region for the first metal and the second metal, and the diffusion coefficients of these metals are smaller than the diffusion coefficients in the first and second mixing regions. The third mixing region (50, 50B) contains the first resin (e.g., epoxy resin) and air (oxygen and nitrogen), and does not contain the first metal (e.g., aluminum) and the second metal (e.g., copper). The third mixing region (50, 50B) has different properties from the first mixing region (10, 10B) and the second mixing region (40, 40B), and suppresses the diffusion of the first metal and the second metal. By including the third mixing region (50, 50B), the above-mentioned effects associated with the diffusion can be suppressed. It is considered that the same effect can be obtained even if the third mixing region (50, 50B) contains the first resin (e.g., epoxy resin) and a gas containing at least nitrogen.

[0050] The maximum dimension Xmax along the longitudinal direction (X-axis) of the anode electrode layer 8 of the second mixing region (40, 40B) is the reference position x O and the dimension between the first position (Xm) along the X-axis direction. In the third mixing region (50, 50B), along the X-axis direction, the position farthest from the reference position Xo is defined as the tip position Xa. The reference dimension Xγ of the third mixing region (50, 50B) is the dimension in the X-axis direction between the position (Xa) in the second mixing region and the first position (Xm) (Xγ = |Xa - Xm|). It is preferable that Xγ < Xmax is satisfied. When the Z-axis direction position giving the position (Xm) and the Z-axis direction position giving the position (Xa) coincide, the reference dimension Xγ can be the minimum dimension in the X-axis direction of the third mixing region (the shortest distance between the second mixing region (40, 40B) and the first mixing region (10, 10B)). The reference dimension (Xγ) in the X-axis direction of the third mixing region as the diffusion suppression region is preferably smaller than the maximum dimension (Xmax) in the X-axis direction of the second mixing region that contributes to the improvement of the adhesion strength, but it may be larger as long as its function can be achieved.

[0051] Next, we will further explain the materials and other aspects of each component that make up a solid electrolytic capacitor.

[0052] 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.

[0053] The protective insulator 16 is made of an insulating material. Inorganic insulating materials and organic insulating materials are known as insulating materials.

[0054] Examples of inorganic insulating materials include silicon oxide (e.g., SiO2) and silicon nitride (e.g., SiN x 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] The anode electrode layer 8 shown in Figure 2 contains the first metal (aluminum). The insulating region (10, 10B) as the first mixed region and the solid electrolyte layer (12, 12B) also contain the first metal (aluminum) as a roughened layer.

[0059] The material in the second mixed region (40, 40B) shown in Figure 2 includes a second metal (e.g., Cu) different from the first metal, and a first resin (e.g., epoxy resin) included in the insulating region (10, 10B). The second metal is a metal included in the first side electrode E1 and includes at least one conductive material (metal) selected from the group consisting of copper (Cu), nickel (Ni), silver (Ag), gold (Au), platinum (Pt), and palladium (Pd). Specifically, the second metal includes at least one conductive material (metal) selected from the group consisting of Cu, Ni, Ni-Cr, Ag, Au, Pt, and Pd.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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).

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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).

[0071] Next, we will briefly explain the manufacturing method of solid electrolytic capacitors.

[0072] 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 include the second mixed region (40, 40B) and the insulating region 30, and these regions are filled with the same material as the insulating region (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.

[0073] (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.

[0074] (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.

[0075] (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.

[0076] (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.

[0077] (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).

[0078] (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.

[0079] (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.

[0080] 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.

[0081] 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.

[0082] Next, a rotating blade is applied to the laminated sheet, with the positive Z-axis direction as the depth direction, and a groove is 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. Thereafter, the same aluminum etching solution as described above is introduced into the groove, and the exposed side surface where the first side electrode E1 is to be formed is lightly etched. Furthermore, the first metal (aluminum) contained in the insulating region (10, 10B) adjacent to this side surface is dissolved, leaving a low-density resin in the same region. Zincate treatment, which is generally used for surface treatment of aluminum, may also be applied. Subsequently, the first side electrode E1 and the second side electrode E2 are formed on the inner surface of the groove by a plating method or the like, and the electrode material is permeated into the low-density resin to form a second mixed region (40, 40B). The grooves are formed at a position where the first side electrode E1 can contact one side of the anode electrode layer 8, and the second side electrode E2 can contact the other side of the cathode electrode layer (14, 14B). Finally, a 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.

[0083] 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 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.

[0084] (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.

[0085] 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.

[0086] The anode electrode layer 8 in the solid electrolytic capacitor element is made of aluminum with a thickness of 10 to 90 μm (corresponding to A1), 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 roughened layer with a thickness (corresponding to M1, M2) of 20-50 μm containing epoxy resin, the insulating layer (11, 11B) consists of a silica filler-containing epoxy resin with a thickness of 20 μm (filler content = 60% by mass), the upper and lower layers of the insulating section 30 are epoxy resins with a thickness (M1, M2) of 20-50 μm, respectively, and the middle layer of the insulating section 30 is a filler-containing epoxy resin with a thickness (A1) of 10-90 μm (filler content = 70% by 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 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, as shown in Figure 1.

[0091] (Evaluation and Results) Figures 7, 8, 9, 10, 11, and 12 are charts showing experimental data for solid electrolytic capacitors. The total thickness (M) of the region including the anode electrode layer 8 and the insulating regions (10, 10B) is shown. TOTALThe environmental resistance of a solid electrolytic capacitor having the following parameters: (μm) = M1 + M2 + A1; the maximum dimension in the X-axis direction of the second mixed region (Xmax (μm)); the thickness of one insulating region (10, 10B) (M1 (M2) (μm)); the thickness of the anode electrode layer 8 (A1 (μm)); the parameter related to the maximum thickness (Xmax (μm)) (β (μm) = Xmax / M1 × A1); and a specific dimension in the X-axis direction of the third mixed region (Xγ = Xa - Xm). 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. Hyphens in the figures and tables indicate that evaluation by testing was not possible.

[0092] (Test 1): Test 1 was a soldering test to evaluate the adhesion strength of solid electrolytic capacitors in their initial state. The test was conducted in accordance with the "Test Method for Plating Adhesion" specified in "JIS H8504," with the soldering area changed to the size of the product terminals (area of ​​the first side electrode). Test 1 was performed on n products (n=11).

[0093] (Test 2): Test 2 is a soldering test that evaluates the adhesive strength of solid electrolytic capacitors after the humidity-resistant steady-state test in Test 1. In the humidity-resistant steady-state test, the solid electrolytic capacitors are placed in an environment of 85°C and 85% RH for 2000 hours. Test 2 was performed on n products (n=11).

[0094] Tests 1 and 2 are evaluated by visually checking whether the first side electrode (copper terminal) is attached to the detached jig after soldering, and then determining the condition. If the first side electrode is attached to the detached jig, it can be determined that the adhesive strength is weak.

[0095] (Evaluation A): In Tests 1 and 2, if the number of products with the first side electrode attached to the jig is 0, this solid electrolytic capacitor is evaluated as (Evaluation A) in Tests 1 and 2.

[0096] (Evaluation B): In Tests 1 and 2, if one product has the first side electrode attached to the jig, this solid electrolytic capacitor is evaluated as (Evaluation B) in Tests 1 and 2.

[0097] (Evaluation C): In Tests 1 and 2, if two products have the first side electrode attached to the jig, this solid electrolytic capacitor is evaluated as (Evaluation C) in Tests 1 and 2.

[0098] (Evaluation D): In Tests 1 and 2, if the number of products with the first side electrode attached to the jig exceeds two, this solid electrolytic capacitor will be evaluated as (Evaluation D) in Tests 1 and 2.

[0099] (Test 3): Test 3 was a solder heat resistance test. A solder heat resistance test (reflow method, in accordance with "Test methods for solderability, solder corrosion resistance of electrodes, and solder heat resistance of surface mount components (SMD)" specified in "JISC60068-2-58") was performed on solid electrolytic capacitors in their initial state to evaluate whether or not delamination occurred inside the product. The longitudinal section of the solid electrolytic capacitor was observed using an optical microscope to observe the delamination state (disconnection) between the first side electrode and the anode electrode layer. The maximum temperature in the reflow was set to 260°C, and heating at the maximum temperature of 260°C for 30 seconds was performed three times. To facilitate observation of the longitudinal section, the XZ plane of the finished solid electrolytic capacitor shown in Figure 1 was polished to expose the first side electrode and anode electrode layer for observation under a microscope. Test 3 was performed on n products (n=11).

[0100] (Evaluation A): If the number of products in Test 3 in which the above delamination condition is observed is 0, this solid electrolytic capacitor is evaluated as (Evaluation A) in Test 3.

[0101] (Evaluation B): If the number of products in which the above delamination condition was observed in Test 3 is 1, this solid electrolytic capacitor is evaluated as (Evaluation B) in Test 3.

[0102] (Evaluation C): If the number of products in Test 3 in which the above delamination condition was observed is 2, this solid electrolytic capacitor will be evaluated as (Evaluation C) in Test 3.

[0103] (Evaluation D): If the number of products in which the above delamination condition is observed exceeds two in Test 3, this solid electrolytic capacitor will be evaluated as (Evaluation D) in Test 3.

[0104] (Test 4): Test 4 is a high-temperature storage test in which the test chip is placed in an environment at a temperature of 150°C for 2000 hours, and the rate of change in the resistance value after this test, which is subjected to a high-temperature environmental load, is measured relative to the initial resistance value. The resistance value was measured between the two terminal electrodes of the test chip using a low resistivity meter. The test chip is a solid electrolytic capacitor in which the cathode electrode layer and the second side electrode are omitted, and instead, a first side electrode that contacts the anode electrode layer is provided on the second side electrode side, and both first side electrodes (both terminals) are short-circuited. Although the test chip is different from a finished solid electrolytic capacitor, the effects of these environmental changes are considered to be similar, so this test can also indirectly evaluate the environmental resistance of solid electrolytic capacitors.

[0105] (Evaluation A): In Test 4, if the resistance change rate is less than 5%, this solid electrolytic capacitor is evaluated as (Evaluation A) in Test 4.

[0106] (Evaluation B): In Test 4, if the resistance change rate is 5% or more and less than 10%, this solid electrolytic capacitor is evaluated as (Evaluation B) in Test 4.

[0107] (Evaluation C): In Test 4, if the resistance change rate is 10% or more and less than 20%, this solid electrolytic capacitor is evaluated as (Evaluation C) in Test 4.

[0108] (Evaluation D): In Test 4, if the resistance change rate is 20% or more, this solid electrolytic capacitor is evaluated as (Evaluation D) in Test 4.

[0109] When the aforementioned β (=Xmax / M1×A1) falls below the lower limit (1.0 (μm)) (Data 1, Data 29), the anchoring effect is weak, and the initial decrease in adhesion makes delamination more likely to occur between the first side electrode and the anode electrode layer. In at least Test 1, this product received a rating of C or lower.

[0110] When β exceeds the upper limit (5.0 (μm)) (Data 27, Data 28, Data 44, Data 45, Data 72, Data 73), the effect of improving adhesion due to the anchoring effect between the first side electrode and the anode electrode layer plateaus, and the initial adhesion does not increase further even if the value becomes larger. Furthermore, as the second mixed region expands, excessive metal diffusion of the first metal (e.g., aluminum) and the second metal (e.g., copper) occurs in a high-temperature, high-humidity environment, leading to the disappearance of the second metal due to the Kirkendall effect, and conversely, a decrease in adhesion. This product received a C rating in Tests 2 and 4.

[0111] If β is within the range of 1 (μm) ≤ β ≤ 5 (μm), the evaluation for Test 1 is either evaluation A or evaluation B, and the evaluation for Test 2 is either evaluation A or evaluation B.

[0112] Furthermore, when the fixed electrolytic capacitor has a third mixing region (data 3-6, 8-11, 13-16, 18-21, 23-26, 31-33, 35-38, 40-43, 47-51, 53-56, 58-61, 63-66, 68-71, 75-76, 78-81, 83-86, 88-89), that is, when the reference dimension Xγ satisfies 1 (μm) ≤ Xγ ≤ 25 (μm), an evaluation of A or B is obtained in Test 4. Since the third mixing region contains at least nitrogen (air = nitrogen + oxygen), it can suppress the diffusion of metal elements between regions adjacent to the third mixing region. In this experiment, air was used, but suppression of metal diffusion is possible as long as at least nitrogen is included.

[0113] When β is within the range of 1 (μm) ≤ β ≤ 5 (μm) and the reference dimension Xγ satisfies Xγ ≤ Xmax, evaluation A or evaluation B is obtained in Tests 1 to 4.

[0114] When the reference dimension Xγ satisfies 3 (μm) ≤ Xγ ≤ 7.5 (μm), evaluation A or evaluation B is obtained in Test 3.

[0115] In the range of various parameters, when the range of an arbitrary parameter P is given by P min ≤ P ≤ P max (P min + ΔP) ≤ P ≤ (P max - ΔP), ΔP = (P max - P min ) × R%, R can be set to 10, or R can be set to 20, R = 30, or R = 40. Also, when an arbitrary parameter P is a specific single numerical value, as the error range, P × 95% ≤ P ≤ P × 105% can be set.

[0116] As described above, the solid electrolytic capacitor of the first aspect stacks a plurality of solid electrolytic capacitor elements via an insulating layer. Each solid electrolytic capacitor element includes a solid electrolyte layer (12, 12B) disposed between an anode electrode layer 8 and a cathode electrode layer (14, 14B), a first side electrode E1 in contact with a side surface of the anode electrode layer 8, a second side electrode E2 in contact with a side surface of the cathode electrode layer (14, 14B), a first mixed region (insulating region (10, 10B)) disposed on the first side electrode side of the anode electrode layer 8 and including a first metal and a first resin, and a second mixed region (40, 40B) disposed between the first side electrode E1 and the first mixed region and including a second metal different from the first metal and a first resin.

[0117] In the solid electrolytic capacitor of the second embodiment, the anode electrode layer 8 includes aluminum, the first metal includes aluminum, the first side electrode E1 includes at least one conductive material selected from the group consisting of copper, nickel, tin, silver, gold, platinum, palladium, indium, bismuth, and antimony, and the second metal is a metal included in the first side electrode E1 and also includes at least one conductive material selected from the group consisting of copper, nickel, silver, gold, platinum, and palladium.

[0118] In the third embodiment of the solid electrolytic capacitor, the anode electrode layer 8 contains aluminum, the first metal contains aluminum, the first side electrode E1 contains copper, and the second metal contains copper.

[0119] In the solid electrolytic capacitor of the fourth embodiment, the first resin includes a thermosetting resin.

[0120] In the solid electrolytic capacitor of the fifth embodiment, the second thickness M1 of the first mixing region (10, 10B) and the maximum dimension Xmax along the longitudinal direction of the anode electrode layer 8 in the second mixing region (40, 40B) satisfy 1.0 (μm) ≤ β ≤ 5.0 (μm), where β = Xmax / M1 × A1.

[0121] In the solid electrolytic capacitor of the fifth embodiment, the thickness M1 of the first mixing region and the maximum dimension Xmax along the longitudinal direction of the anode electrode layer in the second mixing region satisfy 1.0 (μm) ≤ β ≤ 5.0 (μm), where β = Xmax / M1 × A1.

[0122] In the sixth embodiment of the solid electrolytic capacitor, a third mixing region is provided between the first mixing region and the second mixing region to suppress the diffusion of the first metal and the second metal.

[0123] In the solid electrolytic capacitor of the seventh embodiment, the third mixed region contains the first resin and at least nitrogen, but does not contain the first metal and the second metal.

[0124] In the solid electrolytic capacitor of the eighth embodiment, when the longitudinal direction of the anode electrode layer 8 is the X-axis direction, the maximum dimension Xmax in the X-axis direction of the second mixing region and the reference dimension Xγ in the X-axis direction of the third mixing region satisfy Xγ≦Xmax, and the reference dimension Xγ is the distance (Xγ=|Xa-Xm|) between the position in the X-axis direction that gives the maximum dimension Xmax of the second mixing region (Xm) and the position in the X-axis direction that is furthest from the first side electrode of the third mixing region (Xa).

[0125] 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]

[0126] 8... Anode electrode layer, 10... Upper insulating region (first mixed region), 10B... Lower insulating region (first mixed region), 12... Solid electrolyte layer, 14... Upper cathode electrode layer, 14B... Lower cathode electrode layer, 40... Upper mixed region (second mixed region), 40B... Lower mixed region (second mixed region), E1... First side electrode, E2... Second side electrode.

Claims

1. A solid electrolyte layer is placed between the anode electrode layer and the cathode electrode layer, A first side electrode in contact with the side surface of the anode electrode layer, A second side electrode in contact with the side surface of the cathode electrode layer, A first mixed region is disposed on the first side electrode side of the anode electrode layer and includes a first metal and a first resin, A second mixed region is disposed between the first side electrode and the first mixed region and includes a second metal different from the first metal and the first resin, A solid electrolytic capacitor equipped with the following features.

2. The anode electrode layer contains aluminum, The first metal includes aluminum, The first side electrode comprises at least one conductive material selected from the group consisting of copper, nickel, tin, silver, gold, platinum, palladium, indium, bismuth, and antimony. The second metal is, The metal included in the first side electrode, The conductive material includes at least one material selected from the group consisting of copper, nickel, silver, gold, platinum, and palladium. The solid electrolytic capacitor according to claim 1.

3. The anode electrode layer contains aluminum, The first metal includes aluminum, The first side electrode contains copper, The second metal contains copper, The solid electrolytic capacitor according to claim 1.

4. The first resin includes a thermosetting resin. The solid electrolytic capacitor according to claim 1.

5. The thickness M1 of the first mixed region, The maximum dimension Xmax along the longitudinal direction of the anode electrode layer in the second mixed region is: If β = Xmax / M1 × A1, 1.0 (μm)≦β≦5.0 (μm) It satisfies, A solid electrolytic capacitor according to any one of claims 1 to 4.

6. A third mixing region is provided between the first mixing region and the second mixing region, which suppresses the diffusion of the first metal and the second metal. The solid electrolytic capacitor according to claim 1.

7. Between the first and second mixed regions, there is a third mixed region comprising a first resin and at least nitrogen. The solid electrolytic capacitor according to claim 1.

8. The third mixed region does not include the first metal and the second metal. The solid electrolytic capacitor according to claim 7.

9. When the longitudinal direction of the anode electrode layer is the X-axis direction, The maximum dimension Xmax in the X-axis direction of the second mixed region, The reference dimension Xγ in the X-axis direction of the third mixed region is Xγ ≤ Xmax, Satisfying the conditions, The aforementioned reference dimension Xγ is, This is the distance between the position in the X-axis direction that gives the maximum dimension Xmax of the second mixing region and the position in the X-axis direction that is furthest from the first side electrode of the third mixing region. The solid electrolytic capacitor according to claim 7 or 8.

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