Solid electrolytic capacitor and method for manufacturing the same

Abstract

This solid electrolytic capacitor is provided with: a porous sintered body that constitutes a positive electrode; a dielectric layer that is formed on the porous sintered body; a solid electrolyte layer that is formed on the dielectric layer; and a conductor layer that is formed on the solid electrolyte layer so as to constitute a negative electrode. The solid electrolyte layer comprises a first layer that is formed on the dielectric layer. The first layer contains an electrolyte solution. The electrolyte solution is composed, for example, of at least one substance that is selected from the group consisting of ethylene glycol, dimethylformamide, γ-butyrolactone, a polyalkylene glycol, a polyalkylene triol, and derivatives of these compounds. Alternatively, the electrolyte solution is composed of a polymer-based electrolyte solution or a carbonate-based electrolyte solution.

Description

[Technical Field]

[0001] The present disclosure relates to a solid electrolytic capacitor and a method for manufacturing a solid electrolytic capacitor. [Background technology]

[0002] Various solid electrolytic capacitors have been proposed that have a structure in which a porous sintered metal body, a dielectric layer, and a solid electrolyte layer are stacked together. Patent Document 1 discloses an example of a conventional solid electrolytic capacitor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-092237 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to use solid electrolytic capacitors in a wider range of applications, it is preferable to increase the withstand voltage of the solid electrolytic capacitor. Also, solid electrolytic capacitors with a larger capacitance relative to their overall size are desired.

[0005] In view of the above circumstances, one object of the present disclosure is to provide a solid electrolytic capacitor that can improve the withstand voltage and increase the capacitance, and another object of the present disclosure is to provide a method for manufacturing such a solid electrolytic capacitor. [Means for solving the problem]

[0006] A solid electrolytic capacitor according to a first aspect of the present disclosure includes a porous sintered body constituting an anode, a dielectric layer formed on the porous sintered body, a solid electrolyte layer formed on the dielectric layer, and a conductor layer formed on the solid electrolyte layer and constituting a cathode. The solid electrolyte layer includes a first layer formed on the dielectric layer, and the first layer contains an electrolytic solution.

[0007] A second aspect of the present disclosure provides a method for manufacturing a solid electrolytic capacitor, comprising the steps of: forming a porous sintered body constituting an anode; forming a dielectric layer on the porous sintered body; forming a solid electrolyte layer on the dielectric layer; and forming a conductor layer constituting a cathode on the solid electrolyte layer. The step of forming the solid electrolyte layer includes a first treatment of forming a first layer using a first liquid containing an electrolytic solution. [Effects of the Invention]

[0008] According to the above-described configuration, a solid electrolytic capacitor capable of improving the withstand voltage and increasing the capacitance can be obtained.

[0009] Other features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing a solid electrolytic capacitor according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a main portion of the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 3] FIG. 3 is an enlarged cross-sectional view schematically illustrating a main portion of the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 4] FIG. 4 is a flow diagram showing an example of a method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 5] FIG. 5 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 6] FIG. 6 is a cross-sectional view illustrating the method for manufacturing the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a main portion schematically showing a first modified example of the solid electrolytic capacitor according to the first embodiment of the present disclosure. [Figure 8] FIG. 8 is an enlarged cross-sectional view schematically illustrating a main portion of a solid electrolytic capacitor according to a second embodiment of the present disclosure. [Figure 9] FIG. 9 is an enlarged cross-sectional view schematically illustrating a main portion of a solid electrolytic capacitor according to a third embodiment of the present disclosure. [Figure 10] FIG. 10 is an enlarged cross-sectional view schematically illustrating a main portion of a solid electrolytic capacitor according to a fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present disclosure will now be described in detail with reference to the drawings.

[0012] The terms "first," "second," "third," etc. in this disclosure are used to distinguish between words and phrases and are not intended to impose any order on their objects.

[0013] 1 to 3 show a solid electrolytic capacitor according to a first embodiment of the present disclosure. The solid electrolytic capacitor A1 of this embodiment includes a porous sintered body 1, a dielectric layer 2, a solid electrolyte layer 3, a conductor layer 4, a sealing resin 5, an anode terminal 6, and a cathode terminal 7.

[0014] Fig. 1 is a cross-sectional view showing the solid electrolytic capacitor A1, Fig. 2 is an enlarged cross-sectional view showing a main part of the solid electrolytic capacitor A1, and Fig. 3 is an enlarged cross-sectional view schematically showing a main part of the solid electrolytic capacitor A1.

[0015] The porous sintered body 1 constitutes an anode and is made of a valve metal (such as tantalum (Ta) or niobium (Nb)). The shape of the porous sintered body 1 (the macroscopic shape that can be recognized by external observation) is not particularly limited, and may be, for example, a rectangular parallelepiped. In this embodiment, an anode wire 11 is fixed to the porous sintered body 1. A portion of the anode wire 11 penetrates the interior of the porous sintered body 1. The anode wire 11 is made of a valve metal such as tantalum or niobium. The porous sintered body 1 has many minute pores (fine holes) inside.

[0016] The dielectric layer 2 is formed on the porous sintered body 1. In the illustrated example, the dielectric layer 2 is laminated on the surface of the porous sintered body 1. As described above, the porous sintered body 1 has a structure with a large number of pores. Therefore, the dielectric layer 2 not only covers the outer surface (the surface visible from the outside) of the porous sintered body 1, but also covers the inner surfaces of at least some of the pores (for example, pores located relatively close to the outer surface of the porous sintered body 1) (see FIG. 2). The dielectric layer 2 is generally made of an oxide of a valve metal, such as tantalum pentoxide (Ta2O5) or niobium pentoxide (N2bO5).

[0017] The solid electrolyte layer 3 is formed on and covers the dielectric layer 2. As shown in Fig. 3, the solid electrolyte layer 3 of this embodiment includes a first layer 31, a second layer 32, a third layer 33, a fourth layer 34, and a fifth layer 35.

[0018] The first layer 31 is formed on the dielectric layer 2. Note that "the first layer 31 is formed on the dielectric layer 2" does not necessarily mean that the entire first layer 31 is in contact with the dielectric layer 2. For example, another layer (e.g., one or both of the second layer 32 and the third layer 33) may be interposed between the first layer 31 and the dielectric layer 2. As shown in FIG. 3 , the first layer 31 contains an electrolyte solution 311 and a conductive polymer 312. The electrolyte solution 311 is filled between the dispersion or self-doped polymer of the second layer 32 (described later). Examples of the electrolyte solution 311 include ethylene glycol, dimethylformamide, γ-butyrolactone, polyethylene alkylene glycol, polyalkylene triol (or derivatives thereof), polymer-based electrolytes, and carbonate-based electrolytes (e.g., ethylene carbonate, propylene carbonate, etc.). For example, the electrolyte 311 contains at least one of (1) ethylene glycol, dimethylformamide, γ-butyrolactone, polyethylene alkylene glycol, and polyalkylene triol (or their derivatives), (2) a polymer-based electrolyte, and (3) a carbonate-based electrolyte. This also applies to the electrolyte 351 contained in the fifth layer 35, which will be described later. Furthermore, the electrolyte must not evaporate due to the heat generated during reflow. To improve the conductivity of the electrolyte 311, an additive can be used as a solute. Examples of such additives include various anions of adipic acid, carboxylic acid, and sulfonic acid. The conductive polymer 312 is a dispersion or self-doping polymer made of a conductive polymer. The dispersion may be, for example, a polymer or copolymer containing one or two of polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives based on these substances, and may contain various adipic acid, carboxylic acid, or sulfonic acid as a dopant. Self-doping polymers are conductive polymers that have a basic skeleton of, for example, polypyrrole, polythiophene, polyaniline, or polyfuran, and have electron-donating groups such as adipic acid, carboxylic acid, or sulfonic acid induced therein.

[0019] The second layer 32 is formed on the dielectric layer 2. The second layer 32 contains a dispersion or self-doping polymer made of a conductive polymer. The dispersion or self-doping polymer constituting the second layer 32 is in contact with the dielectric layer 2. The dispersion or self-doping polymer constituting the second layer 32 also covers a portion of the dielectric layer 2. That is, the dielectric layer 2 has a portion not covered by the second layer 32. In other words, the dielectric layer 2 has a portion exposed from the second layer 32. The portion of the dielectric layer 2 that contacts the electrolyte solution 311 is the portion of the dielectric layer 2 not covered by the second layer 32. The dispersion constituting the second layer 32 is, for example, a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having the above substances as a basic skeleton, and contains various adipic acids, carboxylic acids, and sulfonic acids as dopants. The self-doping polymer that constitutes the second layer 32 is a conductive polymer that has a basic skeleton of, for example, polypyrrole, polythiophene, polyaniline, or polyfuran, and has electron-donating groups such as adipic acid, carboxylic acid, or sulfonic acid induced therein.

[0020] The third layer 33 is interposed between the first layer 31 and the second layer 32. The third layer 33 covers the dispersion or self-doping polymer of the first layer 31 and the dielectric layer 2. At least a portion of the dielectric layer 2 or the second layer 32 may be exposed through the third layer 33. In this case, the portions of the dielectric layer 2 and the second layer 32 not covered by the third layer 33 are in contact with the electrolyte solution 311. The third layer 33 is made of a conductive polymer and formed by chemical polymerization. The third layer 33 is made of, for example, a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having the above substances as a basic skeleton, and contains various adipic acids, carboxylic acids, and sulfonic acids as dopants.

[0021] The fourth layer 34 is interposed between the first layer 31 and the conductive layer 4. The fourth layer 34 is composed of a conductive polymer dispersion or a self-doping polymer. The dispersion constituting the fourth layer 34 is, for example, a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having the above substances as a basic skeleton, and various adipic acid, carboxylic acid, and sulfonic acid are used as dopants. The self-doping polymer constituting the fourth layer 34 is, for example, a conductive polymer having a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups such as adipic acid, carboxylic acid, and sulfonic acid are introduced. Depending on the formation state of the dispersion or self-doping polymer constituting the fourth layer 34, the fourth layer 34 may be permeated with, for example, the electrolyte solution 311 of the first layer 31 or the electrolyte solution 351 of the fifth layer 35 described below, or may not be permeated with the electrolyte solution 311 or the electrolyte solution 351. In the example shown in FIG. 3, the fourth layer 34 is depicted as being in a state where the electrolytic solution 311 and the electrolytic solution 351 have not penetrated therein.

[0022] The fifth layer 35 is interposed between the fourth layer 34 and the conductive layer 4. The fifth layer 35 contains an electrolyte 351 and a conductive polymer 352. Examples of the electrolyte 351 include ethylene glycol, dimethylformamide, γ-butyrolactone, polyethylene alkylene glycol, polyalkylene triol (or their derivatives), polymer-based electrolytes, and carbonate-based electrolytes (e.g., ethylene carbonate, propylene carbonate, etc.). The electrolyte must not evaporate due to the heat generated during reflow. To improve the conductivity of the electrolyte 351, an additive can be used as a solute. Examples of such additives include various anions such as adipic acid, carboxylic acid, and sulfonic acid. The conductive polymer 352 is a dispersion of a conductive polymer or a self-doped polymer. The dispersion is made of a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having the above substances as a basic skeleton, and various adipic acids, carboxylic acids, and sulfonic acids are contained as dopants. The self-doping polymer is a conductive polymer having a basic skeleton of, for example, polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups such as adipic acids, carboxylic acids, and sulfonic acids are introduced.

[0023] The conductor layer 4 is formed on the solid electrolyte layer 3 and constitutes a cathode. The specific configuration of the conductor layer 4 is not particularly limited as long as it is made of a conductor. In this embodiment, the conductor layer 4 includes an underlayer 41 and an upper layer 42. The underlayer 41 is made of, for example, graphite. In this embodiment, the underlayer 41 is in contact with the fifth layer 35 of the solid electrolyte layer 3. The upper layer 42 is formed on the underlayer 41 and is made of, for example, silver (Ag).

[0024] The sealing resin 5 covers the porous sintered body 1, the anode wire 11, the dielectric layer 2, the solid electrolyte layer 3, and the conductor layer 4. The sealing resin 5 is made of an insulating resin such as an epoxy resin.

[0025] The anode terminal 6 is joined to the anode wire 11, and a portion of the anode terminal 6 is exposed from the sealing resin 5. The anode terminal 6 is made of a Ni-Fe alloy such as a 42 alloy plated with copper (Cu). The portion of the anode terminal 6 exposed from the sealing resin 5 is used as a mounting terminal for surface-mounting the solid electrolytic capacitor A1.

[0026] The cathode terminal 7 is bonded to the conductor layer 4 via a conductive bonding material 71 made of, for example, silver, and a portion of the cathode terminal 7 is exposed from the sealing resin 5. The cathode terminal 7 is made of, for example, a copper-plated Ni-Fe alloy such as 42 alloy. The portion of the cathode terminal 7 exposed from the sealing resin 5 is used as a mounting terminal for surface-mounting the solid electrolytic capacitor A1.

[0027] Next, a method for manufacturing the solid electrolytic capacitor A1 will be described below.

[0028] 4 is a flow diagram showing an example of a method for manufacturing the solid electrolytic capacitor A1. The method for manufacturing the solid electrolytic capacitor A1 of this embodiment includes a porous sintered body forming step, a dielectric layer forming step, a solid electrolyte layer forming step, a conductor layer forming step, and a sealing step.

[0029] In the porous sintered body formation process, a fine powder of a valve metal, such as tantalum or niobium, is prepared. This fine powder is loaded into a mold together with a wire material of a valve metal, such as tantalum or niobium, that will become the anode wire 11. This mold is then used to perform pressure molding to obtain a porous body in which the wire material has permeated. This porous body and the wire material are then sintered. This sintering process sinters the fine powder of the valve metal together, forming a porous sintered body 1 with numerous pores, resulting in an intermediate product B1, as shown in FIG. 5. At this point, the intermediate product B1 contains the porous sintered body 1 and the anode wire 11.

[0030] In the dielectric layer forming step, the intermediate product B1 is supported, for example, by holding the anode wire 11, and the anode wire 11 is immersed in a treatment liquid 20, such as a chemical conversion liquid of an aqueous solution of phosphoric acid. The porous sintered body 1 is then anodized in the treatment liquid 20. As a result, a dielectric layer 2 made of, for example, tantalum pentoxide (TaO) or niobium pentoxide (NbO) is formed on the porous sintered body 1 so as to cover the outer and inner surfaces of the porous sintered body 1.

[0031] In the solid electrolyte layer forming step, the solid electrolyte layer 3 is formed on the dielectric layer 2. When forming the solid electrolyte layer 3 having the above-described configuration, the solid electrolyte layer forming step includes the second treatment, the third treatment, the first treatment, the fourth treatment, and the fifth treatment.

[0032] The second process is a process for forming a second layer 32 on the dielectric layer 2. For example, as shown in FIG. 6, a second process liquid 320 is applied to an intermediate product B1 on which a dielectric layer 2 has been formed. The method for applying the second process liquid 320 to the dielectric layer 2 of the intermediate product B1 is not particularly limited. In addition to the immersion method shown in FIG. 6, any method capable of applying the second process liquid 320 to the dielectric layer 2, such as spray coating, may be used. The second process liquid 320 is a mixture of a conductive polymer dispersion or a self-doping polymer with a solvent. The conductive polymer dispersion may be, for example, a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having the above substances as a basic skeleton, and may contain various adipic acid, carboxylic acid, or sulfonic acid as a dopant. The self-doping polymer is, for example, a conductive polymer having a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups such as adipic acid, carboxylic acid, or sulfonic acid have been introduced. The solvent is one that can uniformly disperse or dissolve the conductive polymer, and examples of suitable solvents include water, ethanol, and organic solvents. After the second treatment liquid 320 is applied to the dielectric layer 2, the intermediate product B1 is removed from the second treatment liquid 320, and the second treatment liquid 320 is dried, for example. This removes the solvent, yielding a second layer 32 made of a dispersion of the conductive polymer or a self-doped polymer.

[0033] The third treatment is a treatment for forming a third layer 33 on the second layer 32. For example, as shown in FIG. 6 , an intermediate product B1 on which the second layer 32 has been formed is immersed in a third treatment liquid 330. The third treatment liquid 330 is, for example, a known monomer solution of the conductive polymer that constitutes the third layer 33 described above. After immersing the intermediate product B1 in the third treatment liquid 330, the intermediate product B1 is pulled out of the third treatment liquid 330, and a chemical polymerization reaction is caused to occur. Then, cleaning and re-chemical conversion treatment are performed as necessary. This forms the third layer 33 made of the conductive polymer. In this embodiment, the third layer 33 covers the second layer 32 and the dielectric layer 2.

[0034] The first process is a process for forming the first layer 31 on an intermediate product B1 on which the second layer 32 and the third layer 33 have been formed. For example, as shown in FIG. 6 , a first process liquid 310 is applied to the intermediate product B1 on which the second layer 32 and the third layer 33 have been formed. The first process liquid 310 corresponds to the first liquid of the present disclosure. In this process, the first process liquid 310 is applied to the third layer 33. If a portion of the dielectric layer 2 and the second layer 32 is exposed from the third layer 33, the first process liquid 310 may be applied to the exposed portion. In this process, the first process liquid 310 fills the gaps between the dispersions of the second layer 32. The method for applying the first process liquid 310 to the intermediate product B1 is not particularly limited, and examples include immersion as shown in FIG. 6 and spray coating. The first process liquid 310 is a mixture of a conductive polymer dispersion or a self-doping polymer, an electrolyte, and a solvent. Conductive polymer dispersions consist of polymers or copolymers containing one or two of polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives of these materials as a basic skeleton, and various adipic acids, carboxylic acids, and sulfonic acids are used as dopants. Self-doping polymers are conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups such as adipic acids, carboxylic acids, and sulfonic acids have been introduced. Examples of electrolytes include ethylene glycol, dimethylformamide, γ-butyrolactone, polyethylene alkylene glycol, polyalkylene triol (or their derivatives), polymer-based electrolytes, and carbonate-based electrolytes (such as ethylene carbonate and propylene carbonate). The electrolyte must not evaporate due to the heat generated during reflow. To improve the conductivity of the electrolyte, additives can be used as solutes. Examples of such additives include anions of various adipic acids, carboxylic acids, and sulfonic acids. The solvent is one that can uniformly disperse or dissolve the conductive polymer, and can be, for example, water, ethanol, an organic solvent, etc. After the first treatment liquid 310 is applied to the intermediate product B1, the intermediate product B1 is pulled out from the first treatment liquid 310, and the first treatment liquid 310 is dried, for example.This removes the solvent, yielding a first layer 31 having an electrolytic solution 311 and a conductive polymer 312 made of a conductive polymer dispersion or a self-doping polymer. The electrolytic solution 311 is filled between the conductive polymers 312 and is in contact with the third layer 33. The concentrations of the conductive polymer dispersion or self-doping polymer and the electrolytic solution in the first treatment liquid 310, as well as the amount of the first treatment liquid 310 to be applied to the intermediate product B1, are appropriately set so as to achieve the above-described state of the electrolytic solution 311 and the conductive polymer 312.

[0035] The fourth process is a process for forming a fourth layer 34 on the first layer 31. For example, as shown in FIG. 6, a fourth process liquid 340 is applied to an intermediate product B1 on which the first layer 31 has been formed. The method for applying the fourth process liquid 340 to the first layer 31 of the intermediate product B1 is not particularly limited. In addition to the immersion method shown in FIG. 6, any method capable of applying the fourth process liquid 340 to the dielectric layer 2, such as spray coating, may be used. The fourth process liquid 340 is a mixture of a conductive polymer dispersion or a self-doping polymer and a solvent. The conductive polymer dispersion may be, for example, a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having the above substances as a basic skeleton, and may contain various adipic acid, carboxylic acid, or sulfonic acid as a dopant. The self-doping polymer is, for example, a conductive polymer having a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups such as adipic acid, carboxylic acid, or sulfonic acid have been introduced. The solvent can be one that can uniformly disperse or dissolve the conductive polymer, and examples of suitable solvents include water, ethanol, and organic solvents. After the fourth treatment liquid 340 is applied to the first layer 31, the intermediate product B1 is removed from the fourth treatment liquid 340, and the fourth treatment liquid 340 is dried, for example. This removes the solvent, resulting in a fourth layer 34 made of a conductive polymer dispersion or self-doping polymer. In this embodiment, by appropriately setting the concentration of the conductive polymer dispersion or self-doping polymer in the fourth treatment liquid 340 and the amount of the fourth treatment liquid 340 applied to the first layer 31, the density of the dispersion that constitutes the fourth layer 34 can be made higher than the density of the dispersion or self-doping polymer that constitutes the second layer 32.

[0036] The fifth process is a process for forming a fifth layer 35 on the fourth layer 34. For example, as shown in FIG. 6, a fifth process liquid 350 is applied to an intermediate product B1 on which the fourth layer 34 has been formed. The fifth process liquid 350 corresponds to the second liquid of the present disclosure. The method for applying the fifth process liquid 350 to the fourth layer 34 is not particularly limited, and examples include immersion as shown in FIG. 6 and spray application. The fifth process liquid 350 is a mixture of a conductive polymer dispersion or a self-doping polymer with an electrolyte and a solvent. The conductive polymer dispersion may be, for example, a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having the above substances as a basic skeleton, and may contain various adipic acids, carboxylic acids, and sulfonic acids as dopants. Self-doping polymers are conductive polymers with a basic skeleton of, for example, polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups such as adipic acid, carboxylic acid, or sulfonic acid have been introduced. Examples of electrolytes include ethylene glycol, dimethylformamide, γ-butyrolactone, polyethylene alkylene glycol, polyalkylene triol (or their derivatives), polymer-based electrolytes, and carbonate-based electrolytes (e.g., ethylene carbonate, propylene carbonate, etc.). Furthermore, the performance required of an electrolyte is one that does not evaporate due to the heat generated during reflow. To improve the conductivity of the electrolyte, additives can be used as solutes. Examples of such additives include various anions of adipic acid, carboxylic acid, and sulfonic acid. The solvent can be one that can uniformly disperse or dissolve the conductive polymer, such as water, ethanol, or an organic solvent. After the fifth treatment liquid 350 is applied to the fourth layer 34, the intermediate product B1 is pulled out of the fifth treatment liquid 350, and the fifth treatment liquid 350 is dried, for example. This removes the solvent, and a fifth layer 35 is obtained that has an electrolytic solution 351 and a conductive polymer 352 made of a conductive polymer or a self-doped polymer. The electrolytic solution 351 is present between the conductive polymers 352 and is in contact with the fourth layer 34.

[0037] The conductor layer forming step is a step of forming a conductor layer 4 on the solid electrolyte layer 3. In this embodiment, first, a base layer 41 is formed. The base layer 41 is formed, for example, by immersing the porous sintered body 1 on which the solid electrolyte layer 3 has been formed in a solution of graphite and an organic solvent, and then pulling it out and drying or firing it. Next, an upper layer 42 is formed. The upper layer 42 is formed, for example, by immersing the intermediate product B1 in a solution of silver filler and a solvent, and then pulling it out and drying or firing it. In this way, the upper layer 42 made of silver is formed, and the conductor layer 4 is obtained.

[0038] The sealing step is a step of covering the intermediate product B1 with sealing resin 5. In this embodiment, prior to the sealing step, an anode terminal 6 and a cathode terminal 7 are attached to the intermediate product B1. The anode terminal 6 is attached using a known method such as welding. The cathode terminal 7 is attached by bonding using a conductive bonding material 71, for example. Then, the sealing resin 5 is formed by molding using a mold or the like.

[0039] Through the above steps, the solid electrolytic capacitor A1 shown in FIGS. 1 to 3 is obtained.

[0040] Next, the effects of the solid electrolytic capacitor A1 and the method for manufacturing the solid electrolytic capacitor A1 will be described.

[0041] The inventors' research has revealed that if the gaps in the dispersion or self-doping polymer constituting the second layer 32 are filled with the conductive polymer formed by chemical polymerization constituting the third layer 33, hydrogen generated during the chemical polymerization may rob the dielectric layer 2 of oxygen, resulting in defects in the dielectric layer 2. According to this embodiment, as shown in FIG. 3 , the solid electrolyte layer 3 includes a first layer 31, which contains an electrolytic solution 311. The electrolytic solution 311 fills the gaps in the dispersion or self-doping polymer constituting the second layer 32. In other words, the gaps in the dispersion or self-doping polymer constituting the second layer 32 are not filled with the conductive polymer formed by chemical polymerization. This structure suppresses defects in the dielectric layer 2 and contributes to improving the withstand voltage. Furthermore, the electrolytic solution 311, which is an electric conductor, fills the gaps in the dispersion or self-doping polymer constituting the second layer 32. Furthermore, the electrolytic solution 311 penetrates more easily into the gaps in the dispersion or self-doping polymer that constitutes the second layer 32 than a treatment solution that forms a conductive polymer by chemical polymerization. This makes it possible to increase the contact area between the solid electrolyte layer 3 and the dielectric layer 2. This, in turn, increases the capacitance of the solid electrolytic capacitor A1. Furthermore, increasing the contact area between the solid electrolyte layer 3 and the dielectric layer 2 reduces the equivalent series resistance (ESR) of the solid electrolytic capacitor A1.

[0042] Since first layer 31 includes conductive polymer 312, the content of electrolyte solution 311 in solid electrolyte layer 3 can be increased more than when first layer 31 is made of only electrolyte solution 311. This is preferable for increasing the capacitance.

[0043] The provision of the fourth layer 34 made of a conductive polymer dispersion or a self-doped polymer further promotes higher voltage resistance and larger capacity, and stabilizes the solid electrolyte layer 3. The provision of the fifth layer 35 containing the electrolytic solution 351 also ensures more reliable contact between the solid electrolyte layer 3 and the conductor layer 4, which is preferable for lowering the ESR.

[0044] By configuring the second layer 32, which is made of a dispersion of a conductive polymer or a self-doped polymer, to be in contact with the dielectric layer 2, the adhesion between the dielectric layer 2 and the solid electrolyte layer 3 can be more reliably maintained.

[0045] 7 to 10 show modifications and other embodiments of the present disclosure. In these figures, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as those in the above embodiment.

[0046] 7 shows a first modified example of the solid electrolytic capacitor A1 in accordance with Embodiment 1. The solid electrolytic capacitor A11 of this modified example differs from the solid electrolytic capacitor A1 described above in the configuration of the fourth layer 34.

[0047] The fourth layer 34 in this example includes an electrolytic solution 341 and a conductive polymer 342. The conductive polymer 342 is a dispersion of a conductive polymer or a self-doping polymer that constitutes the fourth layer 34 of the solid electrolytic capacitor A1 described above. The electrolytic solution 341 is, for example, the electrolytic solution 311 of the first layer 31 or the electrolytic solution 351 of the fifth layer 35 that has permeated into the gaps in the conductive polymer 342. The electrolytic solution 341 may be composed of only the electrolytic solution 311, or may be composed of only the electrolytic solution 351, or may be a mixture of the electrolytic solutions 311 and 351.

[0048] This modification also improves the withstand voltage and increases the capacitance of the solid electrolytic capacitor A11. Furthermore, as can be seen from this modification, even if the fourth layer 34 is formed by a process that does not use a treatment solution containing an electrolytic solution in the fourth treatment described above, the fourth layer 34 can be configured to contain the electrolytic solution 341 by the penetration of the electrolytic solution 311 in the first layer 31 or the electrolytic solution 351 in the fifth layer 35. In the following embodiments, the configuration of the fourth layer 34 can be combined with either the fourth layer 34 of the solid electrolytic capacitor A1 or the fourth layer 34 of the solid electrolytic capacitor A11.

[0049] 8 shows a solid electrolytic capacitor according to a second embodiment of the present disclosure. A solid electrolytic capacitor A2 according to this embodiment differs from the above-described embodiments in the configuration of the solid electrolyte layer 3.

[0050] The solid electrolyte layer 3 of this embodiment does not include the above-mentioned fifth layer 35. Therefore, the fourth layer 34 is in contact with the underlayer 41 of the conductor layer 4.

[0051] This embodiment also improves the withstand voltage and increases the capacitance of the solid electrolytic capacitor A2. As can be seen from this embodiment, the solid electrolyte layer 3 may include the fifth layer 35 or may not include the fifth layer 35. In the following embodiments, the solid electrolyte layer 3 may be configured to include the fifth layer 35 or not include the fifth layer 35 as appropriate.

[0052] 9 shows a solid electrolytic capacitor according to a third embodiment of the present disclosure. A solid electrolytic capacitor A3 according to this embodiment differs from the above-described embodiments in the configuration of the solid electrolyte layer 3.

[0053] The solid electrolyte layer 3 of this embodiment does not include the third layer 33. Therefore, the second layer 32 and the first layer 31 are in contact with each other. More specifically, there are a form in which the electrolytic solution 311 of the first layer 31 directly covers the second layer 32, and a form in which the conductive polymer 312 of the first layer 31 is in contact with the second layer 32.

[0054] This embodiment also improves the withstand voltage and increases the capacitance of the solid electrolytic capacitor A3. Furthermore, according to research by the inventors, the withstand voltage can be further increased by omitting the third layer 33. In the following embodiments, the solid electrolyte layer 3 can be configured to include the second layer 32 or not include the second layer 32 as appropriate.

[0055] 10 shows a solid electrolytic capacitor according to a fourth embodiment of the present disclosure. A solid electrolytic capacitor A4 according to this embodiment differs from the above-described embodiments in the configuration of the first layer 31. The first layer 31 according to this embodiment does not include a conductive polymer 312. The first layer 31 is composed only of an electrolytic solution 311. Therefore, the fourth layer 34 is in contact with the third layer 33.

[0056] This embodiment also improves the withstand voltage and increases the capacitance of the solid electrolytic capacitor A4. Even if the first layer 31 does not have the conductive polymer 312, the capacitance can be increased as long as the gaps in the dispersion or self-doping polymer constituting the third layer 33 are filled with the electrolyte solution 311.

[0057] The solid electrolytic capacitor and the method for manufacturing the solid electrolytic capacitor according to the present disclosure are not limited to the above-described embodiments. The specific configurations of the solid electrolytic capacitor and the method for manufacturing the solid electrolytic capacitor according to the present disclosure can be freely modified in various ways. The present disclosure includes the embodiments described in the following appendices.

[0058] Appendix 1. a porous sintered body constituting an anode; a dielectric layer formed on the porous sintered body; a solid electrolyte layer formed on the dielectric layer; a conductive layer formed on the solid electrolyte layer and constituting a cathode, the solid electrolyte layer includes a first layer formed on the dielectric layer; The first layer includes an electrolyte. Appendix 2. The electrolyte in the first layer is At least one selected from the group consisting of ethylene glycol, dimethylformamide, γ-butyrolactone, polyalkylene glycol, polyalkylene triol, and derivatives thereof; a polymer electrolyte; a carbonate-based electrolyte; 2. The solid electrolytic capacitor according to claim 1, comprising at least one of the following: Appendix 3. 3. The solid electrolytic capacitor according to claim 2, wherein the electrolyte solution contains at least one of adipic acid, carboxylic acid, and sulfonic acid added as an anion. Appendix 4. 4. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein the first layer contains a dispersion of a conductive polymer or a self-doping polymer. Appendix 5. The first layer is a dispersion comprising a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; 5. The solid electrolytic capacitor of claim 4, Appendix 6. the solid electrolyte layer includes a second layer formed on the dielectric layer and having a dispersion of a conductive polymer or a self-doped polymer; the second layer covers a portion of the dielectric layer; 2. The solid electrolytic capacitor according to claim 1, wherein the electrolyte is filled between the dispersion or self-doping polymer of the second layer. Appendix 7. The second layer is a dispersion comprising a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; 7. The solid electrolytic capacitor according to claim 6, Appendix 8. 8. The solid electrolytic capacitor according to claim 6, wherein the solid electrolyte layer includes a third layer interposed between the first layer and the second layer and made of a conductive polymer. Appendix 9. The third layer is a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; 9. The solid electrolytic capacitor according to claim 8, Appendix 10. 10. The solid electrolytic capacitor of claim 8, wherein the solid electrolyte layer includes a fourth layer interposed between the first layer and the conductive layer and having a dispersion of a conductive polymer or a self-doping polymer. Appendix 11. The fourth layer is a dispersion comprising a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; 11. The solid electrolytic capacitor of claim 10, comprising: Appendix 12. 12. The solid electrolytic capacitor of claim 10, wherein the solid electrolyte layer includes a fifth layer interposed between the fourth layer and the conductive layer and having a dispersion of a conductive polymer or a self-doping polymer and an electrolyte solution. Appendix 13. The fifth layer is a dispersion comprising a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; Including, The electrolyte in the fifth layer is At least one selected from the group consisting of ethylene glycol, dimethylformamide, γ-butyrolactone, polyalkylene glycol, polyalkylene triol, and derivatives thereof; a polymer electrolyte; a carbonate-based electrolyte; 13. The solid electrolytic capacitor according to claim 12, comprising at least one of the following: Appendix 14. 14. The solid electrolytic capacitor according to claim 13, wherein the electrolyte solution contains at least one of adipic acid, carboxylic acid, and sulfonic acid added as an anion. Appendix 15. a porous sintered body constituting an anode; forming a dielectric layer on the porous sintered body; forming a solid electrolyte layer on the dielectric layer; forming a conductive layer constituting a cathode on the solid electrolyte layer, The method for manufacturing a solid electrolytic capacitor, wherein the step of forming the solid electrolyte layer includes a first treatment of forming a first layer using a first liquid containing an electrolytic solution. Appendix 16. 16. The method for manufacturing a solid electrolytic capacitor according to claim 15, wherein the first liquid contains a conductive polymer and the electrolytic solution. Appendix 17. the step of forming the solid electrolyte layer includes, before the first treatment, a second treatment of forming a second layer having a dispersion of a conductive polymer or a self-doped polymer on the dielectric layer; the second layer covers a portion of the dielectric layer; 17. The method for producing a solid electrolytic capacitor according to claim 16, wherein in the first treatment, the electrolytic solution is filled between the dispersion or self-doping polymer of the second layer. Appendix 18. 18. The method for manufacturing a solid electrolytic capacitor according to claim 17, wherein the step of forming the solid electrolyte layer includes a third treatment, which is performed after the second treatment and before the first treatment, to form a third layer made of a conductive polymer on the second layer by chemical polymerization. Appendix 19. 19. The method for manufacturing a solid electrolytic capacitor according to claim 18, wherein the step of forming the solid electrolyte layer includes, after the first treatment, a fourth treatment of forming a fourth layer on the first layer, the fourth layer having a dispersion of a conductive polymer or a self-doping polymer. Appendix 20. 20. The method for manufacturing a solid electrolytic capacitor according to claim 19, wherein the step of forming the solid electrolyte layer includes a fifth treatment of, after the fourth treatment, applying a second liquid containing a conductive polymer or a self-doping polymer and an electrolytic solution to the fourth layer. [Explanation of symbols]

[0059] A1, A11, A2, A3, A4: Solid electrolytic capacitors B1: Intermediate product 1: Porous sintered body 2: Dielectric layer 3: Solid electrolyte layer 4: Conductive layer 5: Sealing resin 6: Anode terminal 7: Cathode terminal 11: Anode wire 20: Treatment liquid 31: 1st layer 32: 2nd layer 33: 3rd layer 34: 4th layer 35: 5th layer 41: Base layer 42: Upper layer 71: Conductive adhesive material 310: First treatment liquid 311: Electrolyte 312: Dispersion 320: Second treatment liquid 330: Third processing liquid 340: Fourth processing liquid 341: Electrolyte 342: Dispersion 350: Fifth treatment liquid 351: Electrolyte 352: Dispersion

Claims

1. a porous sintered body constituting an anode; a dielectric layer formed on the porous sintered body; a solid electrolyte layer formed on the dielectric layer; a conductive layer formed on the solid electrolyte layer and constituting a cathode, the solid electrolyte layer includes a first layer formed on the dielectric layer; the first layer contains an electrolyte; the solid electrolyte layer includes a second layer formed on the dielectric layer and having a dispersion of a conductive polymer or a self-doped polymer; the second layer covers a portion of the dielectric layer; A solid electrolytic capacitor, wherein the electrolyte is filled between the dispersion or self-doping polymer of the second layer.

2. The electrolyte in the first layer is at least one selected from the group consisting of ethylene glycol, dimethylformamide, γ-butyrolactone, polyalkylene glycol, polyalkylene triol, and derivatives thereof; a polymer electrolyte; a carbonate-based electrolyte; The solid electrolytic capacitor according to claim 1 , comprising at least one of the following:

3. 3. The solid electrolytic capacitor according to claim 2, wherein the electrolyte solution contains at least one of adipic acid, carboxylic acid, and sulfonic acid added as an anion.

4. 4. The solid electrolytic capacitor according to claim 1, wherein the first layer comprises a dispersion of a conductive polymer or a self-doping polymer.

5. The first layer is a dispersion comprising a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; The solid electrolytic capacitor according to claim 4 , comprising:

6. The second layer is a dispersion comprising a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; The solid electrolytic capacitor of claim 1 , comprising:

7. 2. The solid electrolytic capacitor according to claim 1, wherein the solid electrolyte layer includes a third layer interposed between the first layer and the second layer and made of a conductive polymer.

8. The third layer is a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; The solid electrolytic capacitor according to claim 7 , comprising:

9. 8. The solid electrolytic capacitor of claim 7, wherein the solid electrolyte layer includes a fourth layer interposed between the first layer and the conductive layer and having a dispersion of a conductive polymer or a self-doped polymer.

10. The fourth layer is a dispersion comprising a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; The solid electrolytic capacitor of claim 9 , comprising:

11. 10. The solid electrolytic capacitor of claim 9, wherein the solid electrolyte layer includes a fifth layer interposed between the fourth layer and the conductive layer and having a dispersion of a conductive polymer or a self-doping polymer and an electrolyte solution.

12. The fifth layer is a dispersion comprising a polymer or copolymer containing one or two selected from polypyrrole, polythiophene, polyaniline, polyfuran, or derivatives having these basic skeletons, and containing adipic acid, carboxylic acid, or sulfonic acid as a dopant; Alternatively, self-doping polymers composed of conductive polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, or polyfuran, to which electron-donating groups of adipic acid, carboxylic acid, or sulfonic acid have been introduced; Including, The electrolyte solution in the fifth layer is at least one selected from the group consisting of ethylene glycol, dimethylformamide, γ-butyrolactone, polyalkylene glycol, polyalkylene triol, and derivatives thereof; a polymer electrolyte; a carbonate-based electrolyte; The solid electrolytic capacitor according to claim 11, comprising at least one of the following:

13. 13. The solid electrolytic capacitor according to claim 12, wherein the electrolyte solution contains at least one of adipic acid, carboxylic acid, and sulfonic acid added as an anion.

14. forming a porous sintered body that constitutes an anode; forming a dielectric layer on the porous sintered body; forming a solid electrolyte layer on the dielectric layer; forming a conductive layer constituting a cathode on the solid electrolyte layer, the step of forming the solid electrolyte layer includes a first process of forming a first layer using a first liquid containing an electrolytic solution; the first liquid includes a conductive polymer and the electrolyte solution; the step of forming the solid electrolyte layer includes, before the first treatment, a second treatment of forming a second layer having a dispersion of a conductive polymer or a self-doped polymer on the dielectric layer; the second layer covers a portion of the dielectric layer; In the first treatment, the electrolyte solution is filled between the dispersion or self-doping polymer of the second layer.

15. 15. The method for manufacturing a solid electrolytic capacitor according to claim 14, wherein the step of forming the solid electrolyte layer includes a third treatment, which is performed after the second treatment and before the first treatment, to form a third layer made of a conductive polymer on the second layer by chemical polymerization.

16. 16. The method for manufacturing a solid electrolytic capacitor according to claim 15, wherein the step of forming the solid electrolyte layer includes, after the first treatment, a fourth treatment of forming a fourth layer having a dispersion of a conductive polymer or a self-doping polymer on the first layer.

17. 17. The method for manufacturing a solid electrolytic capacitor according to claim 16, wherein the step of forming the solid electrolyte layer includes a fifth treatment of applying, after the fourth treatment, a second liquid containing a conductive polymer or a self-doping polymer and an electrolytic solution to the fourth layer.

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