WO2022191050A1 - 電解コンデンサおよびその製造方法 - Google Patents

電解コンデンサおよびその製造方法 Download PDF

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Publication number
WO2022191050A1
WO2022191050A1 PCT/JP2022/009293 JP2022009293W WO2022191050A1 WO 2022191050 A1 WO2022191050 A1 WO 2022191050A1 JP 2022009293 W JP2022009293 W JP 2022009293W WO 2022191050 A1 WO2022191050 A1 WO 2022191050A1
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Prior art keywords
layer
solid electrolyte
electrolyte layer
electrolytic capacitor
based polymer
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PCT/JP2022/009293
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English (en)
French (fr)
Japanese (ja)
Inventor
慎司 近藤
和哉 山崎
隆志 川崎
幸司 横山
仁 石本
純久 長崎
祐治 宮地
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to JP2023505494A priority Critical patent/JP7706094B2/ja
Priority to CN202280020493.8A priority patent/CN117063256A/zh
Priority to US18/549,498 priority patent/US12424390B2/en
Publication of WO2022191050A1 publication Critical patent/WO2022191050A1/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/15—Solid electrolytic capacitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/0029—Processes of manufacture
    • H01G9/0036—Formation of the solid electrolyte layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/022—Electrolytes; Absorbents
    • H01G9/025—Solid electrolytes
    • H01G9/028—Organic semiconducting electrolytes, e.g. TCNQ
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/04—Electrodes or formation of dielectric layers thereon
    • H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure

Definitions

  • the present invention relates to an electrolytic capacitor with a solid electrolyte layer and a manufacturing method thereof.
  • An electrolytic capacitor includes a capacitor element, electrode terminals electrically connected to the capacitor element, and an exterior body that seals the capacitor element.
  • a capacitor element includes, for example, an anode body, a dielectric layer covering the anode body, and a solid electrolyte layer covering the dielectric layer.
  • the solid electrolyte layer contains a conductive polymer.
  • a conductive polymer for example, polypyrrole is used as the conductive polymer (eg, Patent Document 1).
  • One aspect of the present invention includes an anode body, a dielectric layer covering the anode body, a first solid electrolyte layer covering the dielectric layer, and a second solid electrolyte layer covering the first solid electrolyte layer.
  • the first solid electrolyte layer includes a first conductive polymer having a polypyrrole as a basic skeleton;
  • the second solid electrolyte layer includes a second conductive polymer having a polythiophene as a basic skeleton;
  • the solid electrolyte layer has a thickness of 1 ⁇ m or more, and relates to the electrolytic capacitor.
  • Another aspect of the present invention includes a first step of preparing an anode body having a dielectric layer formed thereon, and electrolytically polymerizing a precursor of a first conductive polymer having a polypyrrole as a basic skeleton on the dielectric layer. a second step of forming a first solid electrolyte layer containing the first conductive polymer; and a third step of forming a second solid electrolyte layer containing the second conductive polymer, wherein the thickness of the second solid electrolyte layer is 1 ⁇ m or more.
  • FIG. 1 is a cross-sectional view schematically showing an electrolytic capacitor according to one embodiment of the present invention
  • FIG. FIG. 2 is an enlarged cross-sectional view schematically showing a region II in FIG. 1;
  • An electrolytic capacitor comprises an anode body, a dielectric layer covering the anode body, a first solid electrolyte layer covering the dielectric layer, a second solid electrolyte layer covering the first solid electrolyte layer, Prepare.
  • the first solid electrolyte layer (hereinafter also referred to as first layer) includes a first conductive polymer (hereinafter also referred to as polypyrrole-based polymer) having polypyrrole as a basic skeleton.
  • the second solid electrolyte layer (hereinafter also referred to as the second layer) contains a second conductive polymer (hereinafter also referred to as a polythiophene-based polymer) having a polythiophene as a basic skeleton.
  • the thickness of the second solid electrolyte layer is 1 ⁇ m or more. 90% by mass or more of the first layer penetrates into the pores of the anode body. 90 mass % or more of the second layer exists outside the pores of the anode body.
  • the second layer may have the form of a skin layer formed along the outline of the anode body ignoring the pores.
  • the first layer contains a polypyrrole-based polymer, and while it is easy to reduce leakage current, it is difficult to improve capacitance. On the other hand, the capacitance can be improved by disposing the second layer having high conductivity on the first layer.
  • the second layer contains a polythiophene-based polymer, which tends to increase the electrical conductivity, but tends to increase the leakage current.
  • the second layer contains a polythiophene-based polymer, which tends to increase the electrical conductivity, but tends to increase the leakage current.
  • the anode body Since it is advantageous for the anode body to have a large surface area for forming the dielectric layer and the solid electrolyte layer, it usually has a porous portion at least on the surface (surface layer).
  • the porous portion contains many holes (pits).
  • a dielectric layer covers the outer surface of the porous portion and the inner wall surfaces of the pores.
  • the first layer may cover at least the inner wall surfaces of the pores of the porous portion with the dielectric layer interposed therebetween.
  • the first layer may cover the outer surface of the porous section via a dielectric layer, in which case the thickness of the first layer covering the outer surface of the porous section is the thickness of the pores of the porous section. It may be smaller than the thickness of the first layer covering the inner wall surface.
  • the second layer covers the outer surface of the porous portion via the dielectric layer (or the dielectric layer and the first layer). The second layer may further cover the inner wall surfaces of the pores of the porous portion via the dielectric layer and the first layer.
  • the thickness of the second layer is set to 1 ⁇ m or more. Easy to grow. In this case, the second layer is difficult to form in the pores of the porous portion.
  • the second layer may be formed on the outer surface of the porous portion so as to cover the openings of the pores of the porous portion. In this case, the second layer may be formed to the extent that it slightly enters the opening side of the pores of the porous portion.
  • the second layer may be partially in direct contact with the first layer (in the vicinity of the pore openings of the porous portion). A gap may be formed between the first layer covering the inner wall surface of the pores of the porous portion and the second layer covering the outer surface (opening of the pores) of the porous portion.
  • Leakage current can be reduced when the thickness of the second layer (thickness T2 of the second layer 9b in FIG. 2) is 1 ⁇ m or more.
  • the thickness of the second layer is preferably 5 ⁇ m or more.
  • the thickness of the second layer may be 1 ⁇ m or more and 20 ⁇ m or less, or may be 5 ⁇ m or more and 20 ⁇ m or less. When the thickness of the second layer is 20 ⁇ m or less, it is easy to reduce the ESR.
  • the thickness of the second layer means the thickness of the second layer (thickness T2 in FIG. 2) covering the outer surface of the porous portion of the anode body through the dielectric layer and the first layer.
  • the thickness of the second layer can be obtained by the following method. First, the electrolytic capacitor is disassembled, the capacitor element is taken out, and a cross-sectional image of the capacitor element is obtained using a scanning electron microscope (SEM). Using the image, any 10 of the second layer covering the outer surface of the porous portion (outside the line defining the outer shape of the anode body) via the dielectric layer (or the dielectric layer and the first layer) Measure the thickness of the point. An average value of the measured values of the thickness is calculated. The first layer and the second layer can be confirmed by SEM-EDX (energy dispersive X-ray spectroscopy) analysis.
  • SEM-EDX energy dispersive X-ray spectroscopy
  • the thickness of the first layer (the thickness T1 of the first layer 9a in FIG. 2) may be 50 nm or more, or may be 50 nm or more and 100 nm or less. When the thickness of the first layer is 50 nm or more, it is easy to reduce leakage current. When the thickness of the first layer is 100 nm or less, it is easy to cover the inner wall surfaces of the pores of the porous portion with the first layer through the dielectric layer.
  • the thickness of the first layer means the thickness (thickness T1 in FIG. 2) of the first layer covering the inner wall surface of the porous portion through the dielectric layer.
  • the thickness of the first layer can be obtained by the same method as for the thickness of the second layer. That is, in a cross-sectional image obtained by SEM, the thickness of the second layer covering the inner wall surfaces of the pores of the porous portion via the dielectric layer is measured at arbitrary 10 points, and the average value is calculated.
  • the first layer preferably has lower conductivity than the second layer.
  • a second layer having a high conductivity is advantageous in improving the capacitance, but tends to increase the leakage current.
  • the conductivity of the first layer is preferably 200 S/cm or less, more preferably 60 S/cm or more and 150 S/cm or less.
  • the conductivity of the first layer can be obtained by the following method.
  • the electrolytic capacitor is disassembled, the capacitor element is taken out, and the components of the first layer (polypyrrole-based polymer and first dopant) are analyzed.
  • the first treatment liquid may be analyzed.
  • TEM-EELS method electron energy loss spectroscopy
  • NMR method nuclear magnetic resonance spectroscopy
  • Raman spectroscopy and the like can be used as analysis methods. Based on the analysis results, a sample film (for example, 20 to 40 ⁇ m thick) containing the same components as the first layer is formed, and the conductivity of the sample film is obtained as the conductivity of the first layer.
  • the first layer is usually formed by electrolytically polymerizing a polypyrrole polymer precursor in the presence of the first dopant. Therefore, a sample film containing the same components as the first layer is obtained by preparing a sample solution containing a polypyrrole-based polymer precursor and a first dopant, immersing a metal substrate in the sample solution, passing an electric current through the metal substrate, and It can be formed by electropolymerizing the body.
  • a sample film may be formed using the first treatment liquid. Loresta-GX and PSP probes manufactured by Nitto Seiko Analyticc can be used to measure the conductivity of the sample film.
  • the conductivity of the second layer is preferably 350 S/cm or more, more preferably 350 S/cm or more and 800 S/cm or less.
  • the conductivity of the second layer can be determined by the same method as for the first layer. Based on the analysis results, a sample film (for example, 20 to 40 ⁇ m thick) containing the same components as the second layer is formed, and the conductivity of the sample film is obtained as the conductivity of the second layer.
  • a sample film containing the same components (polythiophene-based polymer and second dopant) as the second layer was prepared by preparing a sample solution containing the polythiophene-based polymer and the second dopant, applying the sample solution to the substrate, drying it, can be formed.
  • the second treatment liquid may be analyzed, and the sample film may be formed using the second treatment liquid.
  • the electrolytic capacitor and its manufacturing method will be described in more detail below.
  • the anode body can contain a valve action metal, an alloy containing a valve action metal, a compound containing a valve action metal, and the like. These materials may be used singly or in combination of two or more. For example, aluminum, tantalum, niobium, and titanium are preferably used as valve metals.
  • the anode body may have a porous portion on its surface. Such an anode body can be obtained, for example, by roughening the surface of a base material (such as a foil-like or plate-like base material) containing a valve metal by etching or the like.
  • the anode body may be a molded body of particles containing a valve metal or a sintered body thereof. Since the sintered body has a porous structure, the entire anode body can be the porous portion.
  • the dielectric layer is formed by anodizing the valve action metal on the surface of the anode body by chemical conversion treatment or the like.
  • the dielectric layer may be formed so as to cover at least part of the anode body.
  • a dielectric layer is usually formed on the surface of the anode body. Since the dielectric layer is formed on the surface of the porous portion of the anode body, it is formed along the inner wall surfaces of the holes and pits on the surface of the anode body.
  • the dielectric layer contains an oxide of a valve metal.
  • the dielectric layer contains Ta 2 O 5 when tantalum is used as the valve metal, and the dielectric layer contains Al 2 O 3 when aluminum is used as the valve metal.
  • the dielectric layer is not limited to this, and may be any material as long as it functions as a dielectric.
  • a solid electrolyte layer is formed to cover the dielectric layer.
  • the solid electrolyte layer does not necessarily need to cover the entire dielectric layer (entire surface), and may be formed to cover at least a portion of the dielectric layer.
  • the solid electrolyte layer includes a first layer containing polypyrrole-based polymer and a second layer containing polythiophene-based polymer formed on the first layer. If there is a region on the dielectric layer where the first layer is not formed, the second layer may be formed on the dielectric layer in this region.
  • the first layer contains a polypyrrole-based polymer.
  • Polypyrrole-based polymers include polypyrrole and derivatives thereof.
  • the weight average molecular weight of the polypyrrole-based polymer is, for example, 100 or more and 100,000 or less. In the present specification, the weight average molecular weight is the polystyrene-based weight average molecular weight measured by gel permeation chromatography (GPC).
  • the first layer usually contains a non-self-doped polypyrrole-based polymer.
  • the first layer contains a polypyrrole-based polymer (non-self-doping type) and a first dopant.
  • the conductivity of the first layer can be adjusted according to the first dopant.
  • non-self-doping polypyrrole-based polymer for example, an anionic group (specifically, a sulfonic acid group, a carboxy group , phosphate groups, phosphonate groups, and salts thereof).
  • an anionic group specifically, a sulfonic acid group, a carboxy group , phosphate groups, phosphonate groups, and salts thereof.
  • the first dopant may be a low-molecular-weight dopant.
  • Low-molecular-weight dopants are, for example, dopants capable of forming anions.
  • Specific examples of low-molecular-weight dopants include sulfuric acid, nitric acid, phosphoric acid, boric acid, and organic sulfonic acids.
  • organic sulfonic acids include aromatic sulfonic acids.
  • Aromatic sulfonic acids include benzenesulfonic acid, alkylbenzenesulfonic acid (eg, paratoluenesulfonic acid), naphthalenesulfonic acid, alkylnaphthalenesulfonic acid, and the like.
  • the first dopant may form a polypyrrole-based polymer composite with a polypyrrole-based polymer.
  • the first dopant may be contained in the form of an anion or in the form of a salt.
  • the content of the first dopant in the first layer is, for example, 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the polypyrrole-based polymer.
  • the first layer may contain a conductive polymer other than the polypyrrole-based polymer, it is preferable that the content of the polypyrrole-based polymer is large.
  • the ratio of the polypyrrole-based polymer to the entire conductive polymer contained in the first layer is, for example, 90% by mass or more, and may be 100% by mass.
  • the first layer may be a single layer or may be composed of multiple layers.
  • the polypyrrole-based polymer contained in each layer may be the same or different.
  • the first layer may further contain other components within a range that does not impair the effects of the present invention.
  • the second layer contains a polythiophene-based polymer.
  • Polythiophene-based polymers include polythiophene and derivatives thereof. Examples of polythiophene-based polymers include poly(3,4-ethylenedioxythiophene) (PEDOT).
  • PEDOT poly(3,4-ethylenedioxythiophene)
  • the conductivity of the second layer is high, and a high capacitance can be easily obtained.
  • the weight average molecular weight of the polythiophene-based polymer is, for example, 100 or more and 100,000 or less.
  • the second layer may contain a non-self-doping polythiophene polymer.
  • the second layer contains a polythiophene-based polymer (non-self-doping type) and a second dopant.
  • the conductivity of the second layer can be adjusted according to the second dopant.
  • the polythiophene-based polymer is of a non-self-doping type, the particles of the polythiophene-based polymer are easily dispersed in the second treatment liquid used in the third step (formation of the second layer) to be described later, and a thick second layer is formed. Easy to form.
  • non-self-doping polythiophene-based polymer for example, an anionic group (specifically, a sulfonic acid group, a carboxy group , phosphate groups, phosphonate groups, and salts thereof).
  • an anionic group specifically, a sulfonic acid group, a carboxy group , phosphate groups, phosphonate groups, and salts thereof.
  • the second dopant may be a polymer dopant.
  • a polymeric dopant is, for example, a dopant that can form a polyanion.
  • Specific examples of polymeric dopants include polyvinylsulfonic acid, polystyrenesulfonic acid (PSS), polyallylsulfonic acid, polyacrylsulfonic acid, polymethacrylsulfonic acid, and the like.
  • the second dopant may form a polythiophene-based polymer and a polythiophene-based polymer composite.
  • the second dopant may be contained in the form of a polyanion or in the form of a salt.
  • the content of the second dopant in the second layer is, for example, 0.1 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the polythiophene-based polymer.
  • the second layer may contain a conductive polymer other than the polythiophene-based polymer, it preferably contains a large amount of the polythiophene-based polymer.
  • the ratio of the polythiophene-based polymer to the entire conductive polymer contained in the second layer is, for example, 90% by mass or more, and may be 100% by mass.
  • the second layer may be a single layer or may be composed of multiple layers.
  • the polythiophene-based polymer contained in each layer may be the same or different.
  • the second layer may further contain other components within a range that does not impair the effects of the present invention.
  • FIG. 1 is a cross-sectional view schematically showing the structure of an electrolytic capacitor according to one embodiment of the present invention.
  • FIG. 2 is an enlarged cross-sectional view schematically showing region II in FIG.
  • the electrolytic capacitor 1 includes a capacitor element 2 , a resin sealing material (armor) 3 that seals the capacitor element 2 , and an anode terminal 4 and a cathode terminal that are at least partially exposed to the outside of the resin sealing material 3 . 5 and .
  • the anode terminal 4 and the cathode terminal 5 can be made of, for example, metal (copper or copper alloy, etc.).
  • the resin encapsulant 3 has a substantially rectangular parallelepiped outer shape, and the electrolytic capacitor 1 also has a substantially rectangular parallelepiped outer shape. Epoxy resin, for example, can be used as the material of the resin sealing material 3 .
  • Capacitor element 2 includes anode body 6 , dielectric layer 7 covering anode body 6 , and cathode portion 8 covering dielectric layer 7 .
  • the cathode section 8 includes a solid electrolyte layer 9 covering the dielectric layer 7 and a cathode extraction layer 10 covering the solid electrolyte layer 9 .
  • Cathode extraction layer 10 has carbon layer 11 and silver paste layer 12 .
  • the anode body 6 has a porous portion 6a and includes a region facing the cathode portion 8 and a region not facing the cathode portion 8.
  • the porous portion 6a includes a large number of holes P. As shown in FIG.
  • the holes P may be sponge-like pits or tunnel-like pits.
  • An insulating separation layer 13 is formed so as to cover the surface of the anode body 6 in a strip shape in a portion adjacent to the cathode part 8 in the region of the anode body 6 not facing the cathode part 8 , so that the cathode part 8 and the anode are separated from each other. Contact with the body 6 is restricted.
  • the other portion of the region of anode body 6 that does not face cathode portion 8 is electrically connected to anode terminal 4 by welding.
  • the cathode terminal 5 is electrically connected to the cathode section 8 via an adhesive layer 14 made of a conductive adhesive.
  • the main surfaces 4S and 5S of the anode terminal 4 and the cathode terminal 5 are exposed from the same surface of the resin sealing material 3. This exposed surface is used for solder connection with a board (not shown) on which the electrolytic capacitor 1 is to be mounted.
  • the carbon layer 11 only needs to be conductive, and can be configured using a conductive carbon material (such as graphite), for example.
  • a conductive carbon material such as graphite
  • a composition containing silver powder and a binder resin such as an epoxy resin
  • the configuration of the cathode extraction layer 10 is not limited to this, and may be any configuration having a current collecting function.
  • the solid electrolyte layer 9 is formed so as to cover the dielectric layer 7 .
  • Dielectric layer 7 is formed along the surface of anode body 6 (inner wall surface of hole P and outer surface S of porous portion 6a).
  • the surface of dielectric layer 7 has an uneven shape corresponding to the shape of the surface of anode body 6 .
  • the solid electrolyte layer 9 is preferably formed so as to fill such unevenness of the dielectric layer 7 .
  • the solid electrolyte layer 9 includes a first layer 9a and a second layer 9b.
  • the first layer 9a is formed to cover the inner wall surface of the hole P of the porous portion 6a with the dielectric layer 7 interposed therebetween. As shown in FIG. 2, the first layer 9a does not have to cover the outer surface S of the porous portion 6a.
  • the second layer 9b is formed to cover the outer surface S of the porous portion 6a with the dielectric layer 7 interposed therebetween. As shown in FIG. 2, the second layer 9b may not enter the holes P of the porous portion 6a, and may be formed so as to cover the openings of the holes P of the porous portion 6a. In this case, a gap may exist in the hole P between the first layer 9a and the second layer 9b.
  • the first layer 9a contains a polypyrrole-based polymer
  • the second layer 9b contains a polythiophene-based polymer.
  • the first layer 9a and the second layer 9b have a thickness T1 and a thickness T2, respectively.
  • the thickness T2 of the second layer 9b is 1 ⁇ m or more.
  • the first layer may also be formed to cover the outer surface S of the porous portion 6a with the dielectric layer 7 interposed therebetween.
  • the second layer is formed to cover the outer surface S of the porous portion 6a via the dielectric layer and the first layer.
  • the electrolytic capacitor according to this embodiment is not limited to the electrolytic capacitor having the above structure, and can be applied to electrolytic capacitors having various structures. Specifically, the present invention can be applied to an electrolytic capacitor using a sintered body of metal powder as an anode, a wound type electrolytic capacitor, and the like.
  • a method for manufacturing an electrolytic capacitor comprises a first step of preparing an anode body having a dielectric layer formed thereon, a second step of forming a first layer on the dielectric layer, a first and a third step of forming a second layer on the layer.
  • the first layer contains a polypyrrole-based polymer and the second layer contains a polythiophene-based polymer.
  • the second layer has a thickness of 1 ⁇ m or more.
  • a solid electrolyte layer including a first layer and a second layer is formed by the second step and the third step.
  • the method for manufacturing an electrolytic capacitor may include a step of preparing an anode body prior to the first step.
  • the manufacturing method may further include forming a cathode extraction layer and/or sealing the capacitor element. Each step will be described in more detail below.
  • the anode body is formed by a known method depending on the type of anode body.
  • the anode body can be prepared, for example, by roughening the surface of a foil-like or plate-like base material containing a valve metal.
  • the surface roughening forms a porous portion in the surface layer of the anode body.
  • Roughening may be performed by forming unevenness on the surface of the base material, for example, by etching (eg, electrolytic etching) the surface of the base material.
  • a powder of a valve metal for example, tantalum
  • a rod-shaped anode lead is formed into a desired shape (for example, a block shape) with one longitudinal end of the anode lead embedded in the powder.
  • a shaped body is obtained.
  • the first step is to form a dielectric layer on the anode body.
  • the dielectric layer is formed by anodizing the anode body.
  • Anodization can be performed by a known method such as chemical conversion treatment.
  • the chemical conversion treatment for example, the surface of the anode body is impregnated with the chemical conversion liquid by immersing the anode body in the chemical conversion liquid, and a voltage is applied between the anode body used as the anode and the cathode immersed in the chemical conversion liquid. It can be done by As the conversion liquid, for example, it is preferable to use an aqueous solution of phosphoric acid.
  • Step 2 it is preferable to electropolymerize a polypyrrole-based polymer precursor on the dielectric layer to form a first layer containing the polypyrrole-based polymer.
  • a conductive precoat layer may be formed prior to electrolytic polymerization.
  • the first layer may be formed directly on the dielectric layer, or may be formed via a precoat layer.
  • the first layer is formed using a first treatment liquid containing a polypyrrole-based polymer precursor, a first dopant, and a dispersion medium (or solvent).
  • the first layer may be formed, for example, by immersing the anode body on which the dielectric layer and the precoat layer are formed in the first treatment liquid, and supplying power from the supply electrode using the precoat layer as an electrode.
  • the precoat layer is made of, for example, a conductive material (conductive polymer, inorganic conductive material, etc.).
  • the conductive material constituting the precoat layer is not particularly limited, and known materials can be used, for example.
  • the first layer may be formed by chemically polymerizing a polypyrrole-based polymer precursor.
  • the first layer is formed using a treatment liquid containing a polypyrrole-based polymer precursor, a first dopant, an oxidizing agent, and a dispersion medium (or solvent). After applying the treatment liquid to the dielectric layer, it may be heated.
  • a treatment liquid containing a polypyrrole-based polymer, a first dopant, and a dispersion medium (or solvent) may be adhered to the dielectric layer to form the first layer.
  • polypyrrole-based polymer and the first dopant examples include those exemplified above.
  • polypyrrole-based polymer precursors include monomers constituting the polypyrrole-based polymer and/or oligomers in which several monomers are linked.
  • Dispersion media include, for example, water, organic solvents, or mixtures thereof.
  • organic solvents include monohydric alcohols (methanol, ethanol, propanol, etc.), polyhydric alcohols (ethylene glycol, glycerin, etc.), or aprotic polar solvents (N,N-dimethylformamide, dimethylsulfoxide, acetonitrile, acetone , benzonitrile, etc.).
  • the treatment liquid (first treatment liquid) may further contain other components.
  • a second treatment liquid containing polythiophene-based polymer is attached to the first layer to form a second layer containing polythiophene-based polymer.
  • the anode body having the first layer formed on the dielectric layer may be immersed in the second treatment liquid and then dried to form the second layer.
  • the second treatment liquid may be dried to form the second layer.
  • the second treatment liquid contains a polythiophene-based polymer, a dispersion medium (or solvent), and, if necessary, a second dopant.
  • a polythiophene-based polymer and the second dopant those exemplified above can be used.
  • the dispersion medium (or solvent) those exemplified in the second step can be used.
  • the second treatment liquid may further contain other components.
  • the second treatment liquid for example, a polythiophene-based polymer dispersion (or solution) or a polythiophene-based polymer composite dispersion (or solution) of a polythiophene-based polymer and a second dopant may be used.
  • the second treatment liquid can be obtained, for example, by oxidative polymerization of a polythiophene-based polymer precursor in a dispersion medium (or solvent). Examples of this precursor include a monomer constituting a polythiophene-based polymer and/or an oligomer in which several monomers are linked.
  • the second treatment liquid containing the polythiophene-based polymer composite can be obtained by oxidative polymerization of a polythiophene-based polymer precursor in the presence of the second dopant in a dispersion medium (or solvent).
  • Polythiophene-based polymer composites include PEDOT doped with PSS (PEDOT/PSS).
  • the second treatment liquid may be a dispersion liquid of polythiophene-based polymer (or polythiophene-based polymer composite).
  • the non-self-doping polythiophene-based polymer is less soluble in water than the self-doping-type polythiophene-based polymer, and the polythiophene-based polymer (or polythiophene-based polymer complex) is dissolved in the second treatment liquid containing water.
  • the average particle size of the particles of the polythiophene-based polymer (or polythiophene-based polymer composite) dispersed in the second treatment liquid may be 20 nm or more, It may be 100 nm or more, or 150 nm or more.
  • the upper limit of the average particle size is not particularly limited, it is, for example, 1000 nm or less.
  • the average particle size here means the median size (D50) in the volume-based particle size distribution.
  • the average particle size of the polythiophene-based polymer can be obtained from the particle size distribution by the dynamic light scattering method (DLS). Specifically, the particles are dispersed in water (in a second treatment liquid containing water) by ultrasonic waves, and the particle size distribution of the particles is measured using a dynamic light scattering particle size distribution analyzer (LB-550, manufactured by HORIBA). is measured on a volume basis, and the median diameter (D50) is taken as the average particle diameter.
  • DLS dynamic light scattering particle size distribution analyzer
  • Step of forming cathode extraction layer In this step, a cathode extraction layer is formed by successively laminating a carbon layer and a silver paste layer on the second layer formed in the third step. A capacitor element can be obtained by forming a cathode extraction layer.
  • a conductive adhesive layer is arranged on the surface of the cathode extraction layer, and one end of the cathode terminal is electrically connected to the capacitor element via this adhesive layer.
  • an electrode terminal used in an electrolytic capacitor can be used without any particular limitation, and for example, what is called a lead frame may be used.
  • Step of encapsulating capacitor element with resin encapsulant The formed capacitor element is sealed with a resin material together with a part of each of the anode terminal and the cathode terminal, for example.
  • a resin sealing material is formed by this sealing.
  • the resin material a thermosetting resin (such as an epoxy resin) or a resin composition is preferable.
  • the resin sealing material includes a thermosetting resin or a cured product of a resin composition.
  • ⁇ Example 1>> (Step of forming a dielectric layer on the surface of the anode body)
  • a tantalum sintered body porous body in which a part of the anode lead was embedded was prepared.
  • the tantalum sintered body is a rectangular parallelepiped, and the anode lead is planted from one end face of the rectangular parallelepiped.
  • the anode body was anodized in a phosphoric acid aqueous solution to form a dielectric layer containing tantalum oxide (Ta 2 O 5 ) on the surface of the anode body.
  • Step of forming first layer An aqueous dispersion (first treatment liquid) containing pyrrole and a first dopant (a sulfonate having a naphthalene skeleton) was prepared.
  • the concentration of pyrrole in the first treatment liquid can be appropriately selected, for example, in the range of 1 to 6% by mass, and the concentration of the first dopant in the first treatment liquid is, for example, 3 to 12% by mass. can be selected as appropriate within the range of
  • the anode body with the dielectric layer formed thereon was immersed in a treatment liquid containing a conductive material to form a precoat layer.
  • the anode body on which the dielectric layer and the precoat layer are formed is immersed in the first treatment liquid, and the electropolymerization of pyrrole is allowed to proceed using the precoat layer as an electrode to form the first layer containing polypyrrole and the first dopant (conductivity : 80 S/cm).
  • Step of forming second layer An aqueous dispersion (second treatment liquid) containing a polymer composite (PEDOT/PSS) of PEDOT (polythiophene-based polymer) and a second dopant (PSS) was prepared.
  • the concentration of PEDOT/PSS in the second treatment liquid can be appropriately selected, for example, within the range of 1 to 2% by mass.
  • the average particle size of PEDOT/PSS was 200 nm.
  • the step of drying at 150°C for 10 to 30 minutes was performed once to form the second layer (conductivity: 400 S/cm).
  • the second layer conductivity: 400 S/cm.
  • a solid electrolyte layer composed of the first layer and the second layer was formed.
  • the thickness T1 of the first layer was 100 nm.
  • the thickness T2 of the second layer was 1 ⁇ m.
  • Step of forming cathode extraction layer A carbon layer was formed by applying a dispersion of graphite particles in water to the surface of the solid electrolyte layer and then drying it. Next, after applying a silver paste containing silver particles and a binder resin (epoxy resin) to the surface of the carbon layer, the binder resin was cured by heating to form a silver paste layer. In this manner, a cathode extraction layer composed of a carbon layer and a silver paste layer was formed. Thus, a capacitor element was obtained.
  • a binder resin epoxy resin
  • Step of encapsulating the capacitor element An anode terminal (anode lead frame) was welded to the anode lead, a cathode terminal (cathode lead frame) was connected to the cathode lead layer with a conductive adhesive, and the capacitor element was sealed with a resin sealing material. Thus, the electrolytic capacitor A1 of Example 1 was produced.
  • Table 1 shows the evaluation results.
  • the capacitance and leakage current are shown as relative values when the capacitance and leakage current of the electrolytic capacitor B1 of Comparative Example 1 are set to 100, respectively.
  • the initial ESR (m ⁇ ) at a frequency of 100 kHz was measured using an LCR meter for four-terminal measurement in an environment of 20°C.
  • the electrolytic capacitors A1 to A4 exhibited good ESR.
  • the electrolytic capacitors A1 to A3 in which the thickness T2 of the second layer was 1 to 20 ⁇ m provided a lower ESR.
  • the electrolytic capacitor according to the present invention is suitable for applications that require a high capacitance and a small leakage current compared to electrolytic capacitors.
  • 1 electrolytic capacitor
  • 2 capacitor element
  • 3 resin sealing material
  • 4 anode terminal
  • 4S main surface of anode terminal
  • 5 cathode terminal
  • 5S main surface of cathode terminal
  • 6 anode body
  • 7 Dielectric layer
  • 8 cathode portion
  • 9 solid electrolyte layer
  • 9a first layer
  • 9b second layer
  • 10 cathode extraction layer
  • 11 carbon layer
  • 12 silver paste layer
  • 13 separation layer
  • 14 adhesive layer

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Polyoxymethylene Polymers And Polymers With Carbon-To-Carbon Bonds (AREA)
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US12462986B2 (en) * 2021-04-15 2025-11-04 Panasonic Intellectual Property Management Co., Ltd. Electrolytic capacitor and method for producing same

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