WO2015119047A1 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Solid electrolytic capacitor and manufacturing method thereof Download PDF

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Publication number
WO2015119047A1
WO2015119047A1 PCT/JP2015/052625 JP2015052625W WO2015119047A1 WO 2015119047 A1 WO2015119047 A1 WO 2015119047A1 JP 2015052625 W JP2015052625 W JP 2015052625W WO 2015119047 A1 WO2015119047 A1 WO 2015119047A1
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Prior art keywords
acid
solid electrolytic
conductive polymer
capacitor element
electrolytic capacitor
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PCT/JP2015/052625
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French (fr)
Japanese (ja)
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良弥 小関
坂倉　正郎
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日本ケミコン株式会社
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Priority to JP2015560961A priority Critical patent/JP6610264B2/en
Publication of WO2015119047A1 publication Critical patent/WO2015119047A1/en

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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
    • H01G9/004—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
    • H01G9/0029—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
    • H01G9/15—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
    • H01G9/004—Details
    • H01G9/022—Electrolytes; Absorbents
    • H01G9/035—Liquid electrolytes, e.g. impregnating materials

Definitions

  • the present invention relates to a solid electrolytic capacitor and a method for manufacturing the same, and particularly to a solid electrolytic capacitor suitable for high voltage applications of 80 V or higher and a method for manufacturing the same.
  • An electrolytic capacitor using a metal having a valve action such as tantalum or aluminum is obtained by expanding the dielectric by making the valve action metal as the anode-side counter electrode into the shape of a sintered body or an etching foil. Since it is small and a large capacity can be obtained, it is widely used.
  • a solid electrolytic capacitor using a solid electrolyte as an electrolyte has features such as small size, large capacity, low equivalent series resistance, easy to chip, and suitable for surface mounting. It is indispensable for miniaturization, high functionality and low cost of electronic equipment.
  • an anode foil and a cathode foil made of a valve metal such as aluminum are generally wound with a separator interposed therebetween to form a capacitor element. It is impregnated with a driving electrolyte, and has a sealed structure in which a capacitor element is housed in a metal case such as aluminum or a case made of synthetic resin.
  • a metal case such as aluminum or a case made of synthetic resin.
  • the anode material aluminum, tantalum, niobium, titanium and the like are used, and as the cathode material, the same kind of metal as the anode material is used.
  • Patent Document 1 As solid electrolytes used for solid electrolytic capacitors, manganese dioxide and 7,7,8,8-tetracyanoquinodimethane (TCNQ) complexes are known. There is a technique (Patent Document 1) that focuses on a conductive polymer such as polyethylenedioxythiophene (hereinafter referred to as PEDOT) having excellent adhesion to an oxide film layer of an electrode.
  • PEDOT polyethylenedioxythiophene
  • a solid electrolytic capacitor of a type in which a solid electrolyte layer made of a conductive polymer such as PEDOT is formed on such a wound capacitor element is manufactured as follows. First, the surface of the anode foil made of valve action metal such as aluminum is roughened by electrochemical etching treatment in an aqueous chloride solution to form many etching pits, and then in an aqueous solution such as ammonium borate. A voltage is applied to form an oxide film layer serving as a dielectric (chemical conversion). Similar to the anode foil, the cathode foil is made of a valve metal such as aluminum, and the surface thereof is etched.
  • the anode foil and the cathode foil having the oxide film layer formed on the surface are wound through a separator to form a capacitor element.
  • a polymerizable monomer such as 3,4-ethylenedioxythiophene (hereinafter referred to as EDOT) and an oxidant solution are respectively discharged into the capacitor element that has been subjected to restoration conversion, or immersed in a mixture of both.
  • EDOT 3,4-ethylenedioxythiophene
  • an oxidant solution are respectively discharged into the capacitor element that has been subjected to restoration conversion, or immersed in a mixture of both.
  • the polymerization reaction is accelerated in the capacitor element, and a solid electrolyte layer made of a conductive polymer such as PEDOT is generated.
  • the capacitor element is housed in a bottomed cylindrical outer case to produce a solid electrolytic capacitor.
  • Patent Document 2 proposes a conductive polymer containing polypyrrole or polyaniline in combination with an electrolyte containing ⁇ -butyrolactone or ethylene glycol.
  • JP-A-2-15611 Japanese Patent Laid-Open No. 11-186110
  • the present invention has been proposed to solve the above-described problems, and an object of the present invention is to provide a solid electrolytic capacitor having good ESR characteristics at high temperatures and a method for manufacturing the same.
  • the present inventors have used an ammonium salt of an aromatic carboxylic acid as a solute of an electrolyte solution to be filled in a capacitor element in a high pressure region exceeding 80 V at a high temperature. Based on this finding, the present inventors have completed the present invention.
  • the solid electrolytic capacitor of the present invention uses a conductive polymer dispersion in which conductive polymer particles are dispersed in a solvent in a capacitor element in which an anode electrode foil and a cathode electrode foil are wound via a separator. A solid electrolyte layer is formed, and an electrolyte solution containing an ammonium salt of an aromatic carboxylic acid as a solute is filled in a gap in the capacitor element in which the solid electrolyte layer is formed.
  • An example of a method for producing a solid electrolytic capacitor according to the present invention is as follows. That is, an anode foil and a cathode foil having an oxide film layer formed on the surface are wound through a separator to form a capacitor element, and this capacitor element is subjected to repair formation (first step). Subsequently, the capacitor element is impregnated with a conductive polymer dispersion in which conductive polymer particles are dispersed in a solvent to form a solid electrolyte layer (second step). Thereafter, the capacitor element is immersed in a predetermined electrolytic solution, and the electrolytic solution is filled in the void in the capacitor element in which the solid electrolyte layer is formed (third step). Then, this capacitor element is inserted into the outer case, a sealing rubber is attached to the opening end, and sealing is performed by caulking, and then aging is performed to form a solid electrolytic capacitor (fourth step).
  • the chemical solution for restoration chemical conversion As the chemical solution for restoration chemical conversion, phosphoric acid type chemicals such as ammonium dihydrogen phosphate and diammonium hydrogen phosphate, boric acid type chemicals such as ammonium borate, and adipic acid type chemicals such as ammonium adipate, etc. Although a liquid can be used, it is preferable to use ammonium dihydrogen phosphate.
  • the immersion time is preferably 5 to 120 minutes.
  • the conductive polymer dispersion is preferably a mixture of PEDOT powder and a solid content of a dopant made of polystyrene sulfonic acid.
  • the solvent of the conductive polymer dispersion may be any solvent that dissolves the conductive polymer particles or powder, and water is mainly used.
  • ethylene glycol may be used alone or in combination as a solvent for the dispersion as required. It has been found that the use of ethylene glycol as a solvent for the dispersion can particularly reduce ESR among the electrical properties of the product.
  • Various additives may be added to the conductive polymer dispersion, or neutralization may be performed by adding a cation in order to improve the impregnation property and conductivity of the conductive polymer dispersion.
  • the time for impregnating the conductive polymer dispersion with the capacitor element is determined by the size of the capacitor element, but it is preferably 5 seconds or more for a capacitor element of about ⁇ 5 ⁇ 3L, and 10 seconds or more for a capacitor element of about ⁇ 9 ⁇ 5L, It is necessary to impregnate at least 5 seconds. Even if impregnated for a long time, there is no adverse effect on characteristics. Moreover, after impregnating in this way, it is preferable to hold in a reduced pressure state. The reason is considered to be that the residual amount of the volatile solvent is reduced.
  • the impregnation and drying of the conductive polymer dispersion may be performed a plurality of times as necessary.
  • a solvent that can be used in the electrolytic solution it is preferable to use a solvent having a boiling point of 120 ° C. or higher, which is a life test temperature.
  • the solvent include ⁇ -butyrolactone, polyhydric alcohols such as ethylene glycol, sulfolane, dimethylformamide and the like.
  • the polyhydric alcohol include ethylene glycol, diethylene glycol, dipropylene glycol, 1,2-propanediol, glycerin, 1,3-propanediol, 1,3-butanediol, and 2-methyl-2,4-pentanediol.
  • a low molecular weight polyhydric alcohol is preferable.
  • initial ESR characteristics are improved and high temperature characteristics are also improved.
  • the initial ESR is reduced as compared with the case where a solvent not containing ethylene glycol is used, and the capacitance changes over a long period of use. It has been found that the rate ( ⁇ Cap) is small. The reason is that ethylene glycol has the effect of promoting the extension of the polymer chain of the conductive polymer, and therefore the conductivity is improved and the ESR is lowered.
  • a protic solvent having a hydroxyl group such as ethylene glycol
  • ethylene glycol has a higher affinity with a separator, electrode foil, or conductive polymer than ⁇ -butyrolactone or sulfolane, so that the electrolyte solution is evaporated when using an electrolytic capacitor. In this process, it is considered that charges are easily transferred between the separator, the electrode foil, the conductive polymer, and the electrolyte solution, and ⁇ Cap becomes small.
  • the amount of ethylene glycol added in the mixed solvent is preferably 5 wt% or more, more preferably 40 wt% or more, and most preferably 60 wt% or more.
  • the impregnation property of the electrolyte solution into the capacitor element can be improved.
  • ethylene glycol which has a relatively high viscosity
  • ⁇ -butyrolactone which has a low viscosity
  • the amount of ⁇ -butyrolactone added in the mixed solvent is preferably 40 wt% or less.
  • At least one solvent selected from sulfolane, 3-methylsulfolane, and 2,4-dimethylsulfolane may be additionally used as the ethylene glycol solvent of the ion conductive substance. Since these sulfolane-based solvents have a high boiling point, the transpiration of the electrolyte solution is suppressed and the high temperature characteristics are improved.
  • the addition amount of these sulfolane-based solvents in the mixed solvent is preferably 40 wt% or less.
  • electrolyte solutes include ammonium salts of aromatic carboxylic acids.
  • the aromatic carboxylic acid is preferably an aromatic monocarboxylic acid such as benzoic acid or naphthoic acid, or an aromatic hydroxymonocarboxylic acid such as salicylic acid, mandelic acid or hydroxynaphthoic acid.
  • the polyhydric alcohol is subjected to esterification reaction in the electrolytic solution by exposing the solid electrolytic capacitor to a thermal atmosphere. And an ester of carboxylic acid.
  • the aminium ion loses protons and gasifies due to this esterification reaction, but since it has a high boiling point, it remains in the capacitor case, resulting in an excessive change in the pH of the electrolyte.
  • ammonium salt of the aromatic carboxylic acid used as a solute as in the present invention ammonium ions lose their protons due to esterification and gasify and evaporate. It is considered that an excessive change in pH of the electrolytic solution hardly occurs by being exposed to a hot atmosphere, and deterioration of the conductive polymer is reduced.
  • ammonium salts of aromatic carboxylic acids have good compatibility with conductive polymers in addition to improved chemical conversion as an electrolytic solution. It is considered that the deterioration is less likely to occur, and it is considered that the lower the solute concentration, the more the deterioration of the conductive polymer layer is suppressed.
  • the amount of solute added using an ammonium salt of an aromatic carboxylic acid is preferably 10 wt% or less, more preferably 7 wt% or less, most preferably 5 wt%. %.
  • polyoxyethylene glycol complex compound of boric acid and polysaccharides (mannitol, sorbit, etc.), complex compound of boric acid and polyhydric alcohol, nitro compound (o-nitrobenzoic acid) M-nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol, p-nitrophenol, etc.), phosphoric acid esters and the like.
  • the filling amount is arbitrary as long as the gap in the capacitor element can be filled, but 3 to 100% of the gap in the capacitor element is preferable.
  • the capacitor element is impregnated with a predetermined electrolytic solution, and the electrolytic solution is filled in the gap portion in the capacitor element, whereby the withstand voltage characteristic is improved. It is remarkably improved and the ESR characteristic at high temperature is improved.
  • capacitor elements and solid electrolytic capacitors prepared for the evaluation of the following Examples 1, 2, 5 to 9 and Comparative Examples 1 and 2 are as follows. That is, an electrode drawing means was connected to the anode foil and the cathode foil having an oxide film layer formed on the surface, and both electrode foils were wound through a separator to form a capacitor element having an element shape of 10 ⁇ ⁇ 12.5L. . And this capacitor
  • the PEDOT fine particles and polystyrenesulfonic acid were immersed in a conductive polymer dispersion dispersed in an aqueous solution, and the capacitor element was pulled up and dried at about 150 ° C. Further, this capacitor element was dipped in a conductive polymer dispersion and dried a plurality of times to form a conductive polymer layer made of a conductive polymer on the capacitor element. Then, as shown in Table 1, this capacitor element was filled with an electrolyte solution of an ammonium salt of an aromatic carboxylic acid (Examples 1 and 2). Moreover, the electrolyte solution using triethylamine other than ammonium as a salt was filled (Comparative Examples 1 and 2).
  • the solid electrolytic capacitor has a rated voltage of 100 WV and a rated capacity of 33 ⁇ F.
  • Table 1 also shows the initial ESR characteristics of the solid electrolytic capacitors produced in Examples 1 and 2 and Comparative Examples 1 and 2, and the results of ⁇ Cap when subjected to a no load test at 125 ° C. for 1500 hours. . In the present specification, all ESR characteristics show values at 100 kHz (20 ° C.).
  • Example 1 and Comparative Example 1 are compared, the initial ESR is equivalent, but Example 1 using ammonium benzoate as a salt is more than Comparative Example 1 using triethylamine benzoate. It was found that the characteristic deterioration was small after the high temperature test. Moreover, when Example 2 and Comparative Example 2 are compared, although the initial ESR is equivalent, Example 2 using ammonium salicylate as a salt deteriorates characteristics after a higher temperature test than Comparative Example 2 using triethylamine salicylate. Was found to be small.
  • Example 2 shows the results obtained by impregnating the electrolytic solutions prepared in Examples 5 to 9 into the measuring capacitor element and measuring the withstand voltage.
  • the measuring method is to impregnate the electrolytic solution prepared in Examples 5 to 9 into a capacitor element in which an anode foil having an oxide film and a cathode foil are wound through a separator, and to apply a breakdown voltage at room temperature at a current density of 10 mA. It was measured.
  • the withstand voltage was 320 V when the amount of ammonium benzoate was 13 wt% (Example 9), 350 V (Example 8) at 10 wt%, 400 V at 7 wt% (Example 7), 3 wt. % Was 420 V (Example 6) and 1 wt% was 430 V (Example 5), and the withstand voltage improved as the amount of ammonium benzoate in the solute decreased. For this reason, it has been found that the withstand voltage is drastically improved by setting the amount of ammonium benzoate to 10 wt% or less, particularly 7 wt% or less.
  • the initial characteristics of ESR and tan ⁇ are related to the solid electrolytic capacitors filled with the electrolyte solutions of Examples 1 and 5 to 9 in which the blending ratio of ethylene glycol and ammonium benzoate is changed. And the characteristic after leaving unloaded for 150 hours at 150 ° C. was evaluated. Tan ⁇ represents a value at 120 Hz.
  • the element shape of the capacitor element is 10 ⁇ ⁇ 12.5L, the rated voltage of the solid electrolytic capacitor is 100 WV, and the rated capacity is 33 ⁇ F.
  • Example 1 and Examples 5 to 9 were the same in Example 1 and Examples 5 to 9, but the amount of ammonium benzoate decreased after being left unloaded at 150 ° C. for 2000 hours. Accordingly, the degree of characteristic deterioration is reduced.
  • Example 1 and Examples 5 to 8 are compared with Example 9
  • the amount of ammonium benzoate is reduced to 10 wt% or less, so that the degree of characteristic deterioration is remarkably reduced.
  • Example 1 and Examples 5 to 7 are compared, it can be seen that the degree of characteristic deterioration is further reduced by setting it to 7 wt% or less. For this reason, it has been found that the characteristic deterioration of ESR and tan ⁇ can be further suppressed by setting the amount of ammonium benzoate to 10 wt% or less, preferably 7 wt% or less.

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Abstract

Provided is a solid electrolytic capacitor with excellent ESR characteristics at high temperatures, and a manufacturing method thereof. Using a conductive polymer dispersion obtained by dispersing particles of a conductive polymer in a solvent, a solid electrolyte layer is formed on a capacitor element comprising a positive electrode foil and a negative electrode foil wound with a separator interposed therebetween, and an electrolytic solution which contains the ammonium salt of an aromatic carboxylic acid as a solute is filled in a gap portion inside of the capacitor element on which the solid electrolytic layer was formed, thereby configuring the solid electrolytic capacitor.

Description

固体電解コンデンサ及びその製造方法Solid electrolytic capacitor and manufacturing method thereof
　本発明は、固体電解コンデンサ及びその製造方法に係り、特に、８０Ｖ以上の高圧用途に好適な固体電解コンデンサ及びその製造方法に関するものである。 The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same, and particularly to a solid electrolytic capacitor suitable for high voltage applications of 80 V or higher and a method for manufacturing the same.
　タンタルあるいはアルミニウム等のような弁作用を有する金属を利用した電解コンデンサは、陽極側対向電極としての弁作用金属を焼結体あるいはエッチング箔等の形状にして誘電体を拡面化することにより、小型で大きな容量を得ることができることから、広く一般に用いられている。特に、電解質に固体電解質を用いた固体電解コンデンサは、小型、大容量、低等価直列抵抗であることに加えて、チップ化しやすく、表面実装に適している等の特質を備えていることから、電子機器の小型化、高機能化、低コスト化に欠かせないものとなっている。 An electrolytic capacitor using a metal having a valve action such as tantalum or aluminum is obtained by expanding the dielectric by making the valve action metal as the anode-side counter electrode into the shape of a sintered body or an etching foil. Since it is small and a large capacity can be obtained, it is widely used. In particular, a solid electrolytic capacitor using a solid electrolyte as an electrolyte has features such as small size, large capacity, low equivalent series resistance, easy to chip, and suitable for surface mounting. It is indispensable for miniaturization, high functionality and low cost of electronic equipment.
　この種の固体電解コンデンサにおいて、小型、大容量用途としては、一般に、アルミニウム等の弁作用金属からなる陽極箔と陰極箔をセパレータを介在させて巻回してコンデンサ素子を形成し、このコンデンサ素子に駆動用電解液を含浸し、アルミニウム等の金属製ケースや合成樹脂製のケースにコンデンサ素子を収納し、密閉した構造を有している。なお、陽極材料としては、アルミニウムを初めとしてタンタル、ニオブ、チタン等が使用され、陰極材料には、陽極材料と同種の金属が用いられる。 In this type of solid electrolytic capacitor, as a small-sized and large-capacity application, an anode foil and a cathode foil made of a valve metal such as aluminum are generally wound with a separator interposed therebetween to form a capacitor element. It is impregnated with a driving electrolyte, and has a sealed structure in which a capacitor element is housed in a metal case such as aluminum or a case made of synthetic resin. As the anode material, aluminum, tantalum, niobium, titanium and the like are used, and as the cathode material, the same kind of metal as the anode material is used.
　また、固体電解コンデンサに用いられる固体電解質としては、二酸化マンガンや７、７、８、８－テトラシアノキノジメタン（ＴＣＮＱ）錯体が知られているが、近年、反応速度が緩やかで、かつ陽極電極の酸化皮膜層との密着性に優れたポリエチレンジオキシチオフェン（以下、ＰＥＤＯＴと記す）等の導電性ポリマーに着目した技術（特許文献１）が存在している。 As solid electrolytes used for solid electrolytic capacitors, manganese dioxide and 7,7,8,8-tetracyanoquinodimethane (TCNQ) complexes are known. There is a technique (Patent Document 1) that focuses on a conductive polymer such as polyethylenedioxythiophene (hereinafter referred to as PEDOT) having excellent adhesion to an oxide film layer of an electrode.
　このような巻回型のコンデンサ素子にＰＥＤＯＴ等の導電性ポリマーからなる固体電解質層を形成するタイプの固体電解コンデンサは、以下のようにして作製される。まず、アルミニウム等の弁作用金属からなる陽極箔の表面を塩化物水溶液中での電気化学的なエッチング処理により粗面化して、多数のエッチングピットを形成した後、ホウ酸アンモニウム等の水溶液中で電圧を印加して誘電体となる酸化皮膜層を形成する（化成）。陽極箔と同様に、陰極箔もアルミニウム等の弁作用金属からなり、その表面にはエッチング処理を施される。 A solid electrolytic capacitor of a type in which a solid electrolyte layer made of a conductive polymer such as PEDOT is formed on such a wound capacitor element is manufactured as follows. First, the surface of the anode foil made of valve action metal such as aluminum is roughened by electrochemical etching treatment in an aqueous chloride solution to form many etching pits, and then in an aqueous solution such as ammonium borate. A voltage is applied to form an oxide film layer serving as a dielectric (chemical conversion). Similar to the anode foil, the cathode foil is made of a valve metal such as aluminum, and the surface thereof is etched.
　このようにして表面に酸化皮膜層が形成された陽極箔と陰極箔とを、セパレータを介して巻回してコンデンサ素子を形成する。続いて、修復化成を施したコンデンサ素子に、３，４－エチレンジオキシチオフェン（以下、ＥＤＯＴと記す）等の重合性モノマーと酸化剤溶液をそれぞれ吐出し、あるいは両者の混合液に浸漬して、コンデンサ素子内で重合反応を促進し、ＰＥＤＯＴ等の導電性ポリマーからなる固体電解質層を生成する。その後、このコンデンサ素子を有底筒状の外装ケースに収納して固体電解コンデンサを作製する。 Thus, the anode foil and the cathode foil having the oxide film layer formed on the surface are wound through a separator to form a capacitor element. Subsequently, a polymerizable monomer such as 3,4-ethylenedioxythiophene (hereinafter referred to as EDOT) and an oxidant solution are respectively discharged into the capacitor element that has been subjected to restoration conversion, or immersed in a mixture of both. Then, the polymerization reaction is accelerated in the capacitor element, and a solid electrolyte layer made of a conductive polymer such as PEDOT is generated. Thereafter, the capacitor element is housed in a bottomed cylindrical outer case to produce a solid electrolytic capacitor.
　また、ポリピロール又はポリアニリンを含む導電性ポリマーと、γ－ブチロラクトン又はエチレングリコールを含む電解液とを組み合わせて用いて、電解液による化成皮膜の欠陥部の修復作用により、漏れ電流を低減するとともにＥＳＲを改善することが行われている（特許文献２）。 In addition, by using a conductive polymer containing polypyrrole or polyaniline in combination with an electrolyte containing γ-butyrolactone or ethylene glycol, the leakage current is reduced and ESR is reduced by repairing defects in the chemical conversion film by the electrolyte. Improvement has been made (Patent Document 2).
特開平２－１５６１１号公報JP-A-2-15611 特開平１１－１８６１１０号公報Japanese Patent Laid-Open No. 11-186110
　ところで、近年、車載用や一般電源回路用として用いられるような２５Ｖや６３Ｖ程度の低圧用途のみならず、８０Ｖ以上の高圧用途に使用すべく、高温でのＥＳＲ特性が良好な固体電解コンデンサが要望されている。 By the way, in recent years, there is a demand for a solid electrolytic capacitor having good ESR characteristics at high temperatures so that it can be used not only for low-voltage applications of about 25 V and 63 V used for in-vehicle and general power supply circuits, but also for high-voltage applications of 80 V or higher. Has been.
　本発明は、上記課題を解決するために提案されたものであり、その目的は、高温でのＥＳＲ特性が良好な固体電解コンデンサ及びその製造方法を提供することにある。 The present invention has been proposed to solve the above-described problems, and an object of the present invention is to provide a solid electrolytic capacitor having good ESR characteristics at high temperatures and a method for manufacturing the same.
　本発明者等は、上記課題を解決すべく、種々検討を重ねた結果、８０Ｖを超える高圧領域において、コンデンサ素子に充填する電解液の溶質として芳香族カルボン酸のアンモニウム塩を用いることで高温でのＥＳＲ特性が良好になるとの知見を得、この知見に基づき本発明を完成させるに至った。 As a result of repeated studies to solve the above problems, the present inventors have used an ammonium salt of an aromatic carboxylic acid as a solute of an electrolyte solution to be filled in a capacitor element in a high pressure region exceeding 80 V at a high temperature. Based on this finding, the present inventors have completed the present invention.
　すなわち、本発明の固体電解コンデンサは、陽極電極箔と陰極電極箔とをセパレータを介して巻回したコンデンサ素子に、導電性高分子の粒子が溶媒に分散した導電性高分子分散体を用いて固体電解質層を形成するとともに、該固体電解質層が形成されたコンデンサ素子内の空隙部に、溶質として芳香族カルボン酸のアンモニウム塩を含有した電解液を充填させたことを特徴とする。 That is, the solid electrolytic capacitor of the present invention uses a conductive polymer dispersion in which conductive polymer particles are dispersed in a solvent in a capacitor element in which an anode electrode foil and a cathode electrode foil are wound via a separator. A solid electrolyte layer is formed, and an electrolyte solution containing an ammonium salt of an aromatic carboxylic acid as a solute is filled in a gap in the capacitor element in which the solid electrolyte layer is formed.
　また、前記のような固体電解コンデンサを製造するための方法も本発明の１つである。 In addition, a method for manufacturing the solid electrolytic capacitor as described above is also one aspect of the present invention.
　本発明によれば、高圧領域における高温でのＥＳＲ特性が良好な固体電解コンデンサ及びその製造方法を提供することができる。 According to the present invention, it is possible to provide a solid electrolytic capacitor having a good ESR characteristic at a high temperature in a high-pressure region and a method for manufacturing the same.
　以下、本発明に係る固体電解コンデンサを製造するための代表的な製造手順を開示しつつ、本発明を更に詳しく説明する。 Hereinafter, the present invention will be described in more detail while disclosing representative manufacturing procedures for manufacturing the solid electrolytic capacitor according to the present invention.
（固体電解コンデンサの製造方法）
　本発明に係る固体電解コンデンサの製造方法の一例は、以下の通りである。すなわち、表面に酸化皮膜層が形成された陽極箔と陰極箔をセパレータを介して巻回して、コンデンサ素子を形成し、このコンデンサ素子に修復化成を施す（第１の工程）。続いて、このコンデンサ素子に、導電性高分子の粒子が溶媒に分散した導電性高分子分散体を含浸させて固体電解質層を形成する（第２の工程）。その後、このコンデンサ素子を所定の電解液に浸漬して、固体電解質層が形成されたコンデンサ素子内の空隙部にこの電解液を充填する（第３の工程）。そして、このコンデンサ素子を外装ケースに挿入し、開口端部に封口ゴムを装着して、加締め加工によって封止した後、エージングを行い、固体電解コンデンサを形成する（第４の工程）。 (Method for manufacturing solid electrolytic capacitor)
An example of a method for producing a solid electrolytic capacitor according to the present invention is as follows. That is, an anode foil and a cathode foil having an oxide film layer formed on the surface are wound through a separator to form a capacitor element, and this capacitor element is subjected to repair formation (first step). Subsequently, the capacitor element is impregnated with a conductive polymer dispersion in which conductive polymer particles are dispersed in a solvent to form a solid electrolyte layer (second step). Thereafter, the capacitor element is immersed in a predetermined electrolytic solution, and the electrolytic solution is filled in the void in the capacitor element in which the solid electrolyte layer is formed (third step). Then, this capacitor element is inserted into the outer case, a sealing rubber is attached to the opening end, and sealing is performed by caulking, and then aging is performed to form a solid electrolytic capacitor (fourth step).
（第１の工程における修復化成の化成液）
　修復化成の化成液としては、リン酸二水素アンモニウム、リン酸水素二アンモニウム等のリン酸系の化成液、ホウ酸アンモニウム等のホウ酸系の化成液、アジピン酸アンモニウム等のアジピン酸系の化成液を用いることができるが、なかでも、リン酸二水素アンモニウムを用いることが望ましい。また、浸漬時間は、５～１２０分が望ましい。 (Chemical conversion solution for restoration conversion in the first step)
As the chemical solution for restoration chemical conversion, phosphoric acid type chemicals such as ammonium dihydrogen phosphate and diammonium hydrogen phosphate, boric acid type chemicals such as ammonium borate, and adipic acid type chemicals such as ammonium adipate, etc. Although a liquid can be used, it is preferable to use ammonium dihydrogen phosphate. The immersion time is preferably 5 to 120 minutes.
（第２の工程における導電性高分子分散体）
　導電性高分子分散体は、ＰＥＤＯＴの粉末とポリスチレンスルホン酸からなるドーパントの固形分を混合したものが好ましい。また、導電性高分子分散体の溶媒は、導電性高分子の粒子または粉末が溶解するものであれば良く、主として水が用いられる。ただし、必要に応じて分散体の溶媒としてエチレングリコールを単独又は混合して用いてもよい。分散体の溶媒としてエチレングリコールを用いると、製品の電気的特性のうち、特にＥＳＲを低減できることが判明している。なお、導電性高分子分散体の含浸性、電導度の向上のため、導電性高分子分散体に各種添加剤を添加したり、カチオン添加による中和を行っても良い。 (Conductive polymer dispersion in the second step)
The conductive polymer dispersion is preferably a mixture of PEDOT powder and a solid content of a dopant made of polystyrene sulfonic acid. The solvent of the conductive polymer dispersion may be any solvent that dissolves the conductive polymer particles or powder, and water is mainly used. However, ethylene glycol may be used alone or in combination as a solvent for the dispersion as required. It has been found that the use of ethylene glycol as a solvent for the dispersion can particularly reduce ESR among the electrical properties of the product. Various additives may be added to the conductive polymer dispersion, or neutralization may be performed by adding a cation in order to improve the impregnation property and conductivity of the conductive polymer dispersion.
（導電性高分子分散体への含浸）
　コンデンサ素子を導電性高分子分散体に含浸する時間は、コンデンサ素子の大きさによって決まるが、φ５×３Ｌ程度のコンデンサ素子では５秒以上、φ９×５Ｌ程度のコンデンサ素子では１０秒以上が望ましく、最低でも５秒間は含浸することが必要である。なお、長時間含浸しても特性上の弊害はない。また、このように含浸した後、減圧状態で保持すると好適である。その理由は、揮発性溶媒の残留量が少なくなるためであると考えられる。また、導電性高分子分散体の含浸ならびに乾燥は、必要に応じて複数回行ってもよい。 (Impregnation into conductive polymer dispersion)
The time for impregnating the conductive polymer dispersion with the capacitor element is determined by the size of the capacitor element, but it is preferably 5 seconds or more for a capacitor element of about φ5 × 3L, and 10 seconds or more for a capacitor element of about φ9 × 5L, It is necessary to impregnate at least 5 seconds. Even if impregnated for a long time, there is no adverse effect on characteristics. Moreover, after impregnating in this way, it is preferable to hold in a reduced pressure state. The reason is considered to be that the residual amount of the volatile solvent is reduced. The impregnation and drying of the conductive polymer dispersion may be performed a plurality of times as necessary.
（第３の工程における電解液）
　電解液に使用できる溶媒としては、その沸点が、寿命試験温度である１２０℃以上の溶媒を用いることが好ましい。溶媒の例としては、γ－ブチロラクトン、エチレングリコールなどの多価アルコール、スルホラン、ジメチルホルムアミド等が挙げられる。多価アルコールとしては、エチレングリコール、ジエチレングリコール、ジプロピレングリコール、１，２－プロパンジオール、グリセリン、１，３－プロパンジオール、１，３－ブタンジオール、２－メチル－２，４－ペンタンジオールなどの低分子量の多価アルコールがよく、特に、エチレングリコールを含む溶媒を用いると、初期のＥＳＲ特性が良好となり、さらに高温特性も良好となる。 (Electrolytic solution in the third step)
As a solvent that can be used in the electrolytic solution, it is preferable to use a solvent having a boiling point of 120 ° C. or higher, which is a life test temperature. Examples of the solvent include γ-butyrolactone, polyhydric alcohols such as ethylene glycol, sulfolane, dimethylformamide and the like. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, dipropylene glycol, 1,2-propanediol, glycerin, 1,3-propanediol, 1,3-butanediol, and 2-methyl-2,4-pentanediol. A low molecular weight polyhydric alcohol is preferable. In particular, when a solvent containing ethylene glycol is used, initial ESR characteristics are improved and high temperature characteristics are also improved.
　即ち、エチレングリコールなどの多価アルコールを含む溶媒を用いた場合、エチレングリコールを含まない溶媒を用いた場合と比較して、初期のＥＳＲが低下するとともに、長時間の使用において静電容量の変化率（ΔＣａｐ）が小さいことが判明している。その理由は、エチレングリコールは、導電性ポリマーのポリマー鎖の伸張を促進する効果があるため、電導度が向上し、ＥＳＲが低下すると考えられる。また、γ－ブチロラクトンやスルホランよりも、エチレングリコールのようなヒドロキシル基を有するプロトン性溶媒の方がセパレータや電極箔、導電性ポリマーとの親和性が高いため、電解コンデンサ使用時の電解質溶液が蒸散する過程において、セパレータや電極箔、導電性ポリマーと電解質溶液との間で電荷の受け渡しが行われやすく、ΔＣａｐが小さくなると考えられる。また、混合溶媒中におけるエチレングリコールの添加量は、好ましくは５ｗｔ％以上、さらに好ましくは４０ｗｔ％以上、最も好ましくは６０ｗｔ％以上である。 That is, when a solvent containing a polyhydric alcohol such as ethylene glycol is used, the initial ESR is reduced as compared with the case where a solvent not containing ethylene glycol is used, and the capacitance changes over a long period of use. It has been found that the rate (ΔCap) is small. The reason is that ethylene glycol has the effect of promoting the extension of the polymer chain of the conductive polymer, and therefore the conductivity is improved and the ESR is lowered. In addition, a protic solvent having a hydroxyl group, such as ethylene glycol, has a higher affinity with a separator, electrode foil, or conductive polymer than γ-butyrolactone or sulfolane, so that the electrolyte solution is evaporated when using an electrolytic capacitor. In this process, it is considered that charges are easily transferred between the separator, the electrode foil, the conductive polymer, and the electrolyte solution, and ΔCap becomes small. Further, the amount of ethylene glycol added in the mixed solvent is preferably 5 wt% or more, more preferably 40 wt% or more, and most preferably 60 wt% or more.
　また、電解質溶液の溶媒としてγ－ブチロラクトンを所定量添加させることで、電解質溶液のコンデンサ素子への含浸性を改善できる。比較的粘性の高いエチレングリコールと粘性が低いγ－ブチロラクトンを用いることで、コンデンサ素子への含浸性を高め、初期特性及び長時間の使用での良好な特性を維持とともに、低温での充放電特性が良好となる。混合溶媒中におけるγ－ブチロラクトンの添加量は、好ましくは、４０ｗｔ％以下である。 Also, by adding a predetermined amount of γ-butyrolactone as a solvent for the electrolyte solution, the impregnation property of the electrolyte solution into the capacitor element can be improved. By using ethylene glycol, which has a relatively high viscosity, and γ-butyrolactone, which has a low viscosity, it improves the impregnation of capacitor elements, maintains the initial characteristics and good characteristics for long-term use, and also charges and discharges at low temperatures. Becomes better. The amount of γ-butyrolactone added in the mixed solvent is preferably 40 wt% or less.
　さらに、イオン伝導性物質のエチレングリコール溶媒に、スルホラン、３－メチルスルホラン、２，４－ジメチルスルホランから選ばれる少なくとも１種の溶媒を追加的に用いてもよい。これらスルホラン系の溶媒は高沸点であるため、電解質溶液の蒸散を抑制し、高温特性が良好になる。混合溶媒中のこれらスルホラン系の溶媒の添加量は、好ましくは、４０ｗｔ％以下である。 Furthermore, at least one solvent selected from sulfolane, 3-methylsulfolane, and 2,4-dimethylsulfolane may be additionally used as the ethylene glycol solvent of the ion conductive substance. Since these sulfolane-based solvents have a high boiling point, the transpiration of the electrolyte solution is suppressed and the high temperature characteristics are improved. The addition amount of these sulfolane-based solvents in the mixed solvent is preferably 40 wt% or less.
　電解質の溶質としては、芳香族カルボン酸のアンモニウム塩が挙げられる。この芳香族カルボン酸としては、安息香酸若しくはナフトエ酸等の芳香族モノカルボン酸、又はサリチル酸、マンデル酸若しくはヒドロキシナフトエ酸等の芳香族ヒドロキシモノカルボン酸であることが好ましい。 Examples of electrolyte solutes include ammonium salts of aromatic carboxylic acids. The aromatic carboxylic acid is preferably an aromatic monocarboxylic acid such as benzoic acid or naphthoic acid, or an aromatic hydroxymonocarboxylic acid such as salicylic acid, mandelic acid or hydroxynaphthoic acid.
　特に、溶質としてカルボン酸塩を用い、溶媒としてエチレングリコールなどの多価アルコールを用いた電解液においては、固体電解コンデンサが熱雰囲気下に晒されることで電解液中のエステル化反応によって多価アルコールとカルボン酸のエステルが生成される。アミン塩などにおいては、このエステル化反応によってアミニウムイオンがプロトンを失ってガス化するが、沸点が高いため、コンデンサケース内に残留し、この結果電解液のｐＨが過剰に変化することになり、導電性高分子の劣化が生じ易くなるが、本発明のように溶質として用いた芳香族カルボン酸のアンモニウム塩においては、エステル化によってアンモニウムイオンがプロトンを失ってガス化して蒸散していくため、熱雰囲気下に晒されることで電解液のｐＨの過剰な変化が生じにくく、導電性高分子の劣化が低減されると考えられる。 In particular, in an electrolytic solution using a carboxylate salt as a solute and a polyhydric alcohol such as ethylene glycol as a solvent, the polyhydric alcohol is subjected to esterification reaction in the electrolytic solution by exposing the solid electrolytic capacitor to a thermal atmosphere. And an ester of carboxylic acid. In amine salts and the like, the aminium ion loses protons and gasifies due to this esterification reaction, but since it has a high boiling point, it remains in the capacitor case, resulting in an excessive change in the pH of the electrolyte. However, in the ammonium salt of the aromatic carboxylic acid used as a solute as in the present invention, ammonium ions lose their protons due to esterification and gasify and evaporate. It is considered that an excessive change in pH of the electrolytic solution hardly occurs by being exposed to a hot atmosphere, and deterioration of the conductive polymer is reduced.
　また、種々の溶質を評価した結果、芳香族カルボン酸のアンモニウム塩は、電解液としての化成性の向上に加え、導電性高分子との相性が良く、高温耐久試験における導電性高分子層を劣化させにくいものと考えられ、これは溶質濃度が低いほど導電性高分子層の劣化が抑制されるものと考えられる。 In addition, as a result of evaluating various solutes, ammonium salts of aromatic carboxylic acids have good compatibility with conductive polymers in addition to improved chemical conversion as an electrolytic solution. It is considered that the deterioration is less likely to occur, and it is considered that the lower the solute concentration, the more the deterioration of the conductive polymer layer is suppressed.
　上記電解液においては、後述する実施例の結果からも明らかなとおり、芳香族カルボン酸のアンモニウム塩を用いた溶質の添加量を好ましくは１０ｗｔ％以下、より好ましくは７ｗｔ％以下、最も好ましくは5ｗｔ％未満とする。 In the above electrolytic solution, as is apparent from the results of Examples described later, the amount of solute added using an ammonium salt of an aromatic carboxylic acid is preferably 10 wt% or less, more preferably 7 wt% or less, most preferably 5 wt%. %.
　さらに、電解質溶液の添加剤として、ポリオキシエチレングリコール、ホウ酸と多糖類（マンニット、ソルビットなど）との錯化合物、ホウ酸と多価アルコールとの錯化合物、ニトロ化合物（ｏ－ニトロ安息香酸、ｍ－ニトロ安息香酸、ｐ－ニトロ安息香酸、ｏ－ニトロフェノール、ｍ－ニトロフェノール、ｐ－ニトロフェノールなど）、リン酸エステルなどが挙げられる。 Furthermore, as an additive for the electrolyte solution, polyoxyethylene glycol, complex compound of boric acid and polysaccharides (mannitol, sorbit, etc.), complex compound of boric acid and polyhydric alcohol, nitro compound (o-nitrobenzoic acid) M-nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol, p-nitrophenol, etc.), phosphoric acid esters and the like.
（電解液の充填条件）
　上記のような電解液をコンデンサ素子に充填する場合、その充填量は、コンデンサ素子内の空隙部に充填できれば任意であるが、コンデンサ素子内の空隙部の３～１００％が好ましい。 (Electrolytic solution filling conditions)
When the capacitor element is filled with the electrolytic solution as described above, the filling amount is arbitrary as long as the gap in the capacitor element can be filled, but 3 to 100% of the gap in the capacitor element is preferable.
（作用・効果）
　上記のように、コンデンサ素子内に導電性ポリマーを形成した後、このコンデンサ素子を所定の電解液に含浸させて、コンデンサ素子内の空隙部にこの電解液を充填することにより、耐電圧特性が著しく向上するとともに高温でのＥＳＲ特性が良好になる。 (Action / Effect)
As described above, after forming a conductive polymer in the capacitor element, the capacitor element is impregnated with a predetermined electrolytic solution, and the electrolytic solution is filled in the gap portion in the capacitor element, whereby the withstand voltage characteristic is improved. It is remarkably improved and the ESR characteristic at high temperature is improved.
　この理由については、上記のとおり作製したコンデンサ素子内には従来のような重合反応残余物がそもそも存在せず、導電性ポリマーの耐電圧より低い反応残余物による耐電圧の低下を抑制できる結果、耐電圧を向上させるためと考えられる。また、上述したように、芳香族カルボン酸のアンモニウム塩を用いることにより、電解液としての化成性の向上に加え、導電性高分子との相性が向上し、高温耐久試験における導電性高分子層の劣化が抑制されるものと考えられる。 For this reason, there are no conventional polymerization reaction residues in the capacitor element produced as described above, and as a result, it is possible to suppress a decrease in withstand voltage due to a reaction residue lower than the withstand voltage of the conductive polymer. This is considered to improve the withstand voltage. In addition, as described above, by using an ammonium salt of an aromatic carboxylic acid, in addition to improving the chemical conversion as an electrolytic solution, the compatibility with the conductive polymer is improved, and the conductive polymer layer in the high temperature durability test. It is thought that deterioration of the is suppressed.
　続いて、以下のようにして製造した実施例及び比較例に基づいて本発明をさらに詳細に説明する。 Subsequently, the present invention will be described in more detail based on Examples and Comparative Examples produced as follows.
　まず、以下の各実施例１、２、５～９及び比較例１、２の評価のために作成されるコンデンサ素子及び固体電解コンデンサは次の通りである。すなわち、表面に酸化皮膜層が形成された陽極箔と陰極箔に電極引き出し手段を接続し、両電極箔をセパレータを介して巻回して、素子形状が１０φ×１２．５Ｌのコンデンサ素子を形成した。そして、このコンデンサ素子をリン酸二水素アンモニウム水溶液に４０分間浸漬して、修復化成を行った。その後、ＰＥＤＯＴの微粒子とポリスチレンスルホン酸を水溶液に分散した導電性高分子分散体に浸漬し、コンデンサ素子を引き上げて約１５０℃で乾燥した。さらに、このコンデンサ素子の導電性高分子分散体への浸漬－乾燥を複数回繰り返して、コンデンサ素子に導電性高分子からなる導電性高分子層を形成した。その後、このコンデンサ素子に、表１に示すように、芳香族カルボン酸のアンモニウム塩の電解液を充填した（実施例１、２）。また、塩としてアンモニウム以外のトリエチルアミンを用いた電解液を充填した（比較例１、２）。そして、これらのコンデンサ素子を有底筒状の外装ケースに挿入し、開口端部に封口ゴムを装着して、加締め加工によって封止した。その後に、電圧印加によってエージングを行い、固体電解コンデンサを形成した。なお、この固体電解コンデンサの定格電圧は１００ＷＶ、定格容量は３３μＦである。
Figure JPOXMLDOC01-appb-T000001
 First, capacitor elements and solid electrolytic capacitors prepared for the evaluation of the following Examples 1, 2, 5 to 9 and Comparative Examples 1 and 2 are as follows. That is, an electrode drawing means was connected to the anode foil and the cathode foil having an oxide film layer formed on the surface, and both electrode foils were wound through a separator to form a capacitor element having an element shape of 10φ × 12.5L. . And this capacitor | condenser element was immersed in ammonium dihydrogen phosphate aqueous solution for 40 minutes, and restoration | restoration conversion was performed. Thereafter, the PEDOT fine particles and polystyrenesulfonic acid were immersed in a conductive polymer dispersion dispersed in an aqueous solution, and the capacitor element was pulled up and dried at about 150 ° C. Further, this capacitor element was dipped in a conductive polymer dispersion and dried a plurality of times to form a conductive polymer layer made of a conductive polymer on the capacitor element. Then, as shown in Table 1, this capacitor element was filled with an electrolyte solution of an ammonium salt of an aromatic carboxylic acid (Examples 1 and 2). Moreover, the electrolyte solution using triethylamine other than ammonium as a salt was filled (Comparative Examples 1 and 2). And these capacitor | condenser elements were inserted in the bottomed cylindrical exterior case, sealing rubber | gum was attached to the opening edge part, and it sealed by the crimping process. Thereafter, aging was performed by applying a voltage to form a solid electrolytic capacitor. The solid electrolytic capacitor has a rated voltage of 100 WV and a rated capacity of 33 μF.
Figure JPOXMLDOC01-appb-T000001
　実施例１、２および比較例１、２で作製した固体電解コンデンサの初期のＥＳＲ特性および１２５℃、１５００時間無負荷放置試験を行ったときのＥＳＲ特性、ΔＣａｐの結果を表１に併せて示す。なお、本明細書において、ＥＳＲ特性はすべて１００ｋＨｚ（２０℃）における値を示している。 Table 1 also shows the initial ESR characteristics of the solid electrolytic capacitors produced in Examples 1 and 2 and Comparative Examples 1 and 2, and the results of ΔCap when subjected to a no load test at 125 ° C. for 1500 hours. . In the present specification, all ESR characteristics show values at 100 kHz (20 ° C.).
　表１の結果より、実施例１と比較例１を比較すると、初期のＥＳＲは同等であるものの、塩として安息香酸アンモニウムを用いた実施例１の方が安息香酸トリエチルアミンを用いた比較例１より高温試験後において特性劣化が小さいことが分かった。
　また、実施例２と比較例２を比較すると、初期のＥＳＲは同等であるものの、塩としてサリチル酸アンモニウムを用いた実施例２の方がサリチル酸トリエチルアミンを用いた比較例２より高温試験後において特性劣化が小さいことが分かった。 From the results in Table 1, when Example 1 and Comparative Example 1 are compared, the initial ESR is equivalent, but Example 1 using ammonium benzoate as a salt is more than Comparative Example 1 using triethylamine benzoate. It was found that the characteristic deterioration was small after the high temperature test.
Moreover, when Example 2 and Comparative Example 2 are compared, although the initial ESR is equivalent, Example 2 using ammonium salicylate as a salt deteriorates characteristics after a higher temperature test than Comparative Example 2 using triethylamine salicylate. Was found to be small.
　次に、表２に示すように、エチレングリコールと安息香酸アンモニウムとの配合比を変化させた電解液を作製し（実施例５～実施例９）、これらの電解液の耐電圧を評価した。実施例５～９で作製した電解液を測定用のコンデンサ素子に含浸し耐電圧を測定した結果を表２に示す。測定方法は、酸化皮膜を有する陽極箔と陰極箔をセパレータを介して巻回したコンデンサ素子に実施例５～９で作製した電解液を含浸し、１０ｍＡの電流密度で室温下でブレークダウン電圧を測定した。
Figure JPOXMLDOC01-appb-T000002
 Next, as shown in Table 2, electrolytes with different blending ratios of ethylene glycol and ammonium benzoate were prepared (Examples 5 to 9), and the withstand voltage of these electrolytes was evaluated. Table 2 shows the results obtained by impregnating the electrolytic solutions prepared in Examples 5 to 9 into the measuring capacitor element and measuring the withstand voltage. The measuring method is to impregnate the electrolytic solution prepared in Examples 5 to 9 into a capacitor element in which an anode foil having an oxide film and a cathode foil are wound through a separator, and to apply a breakdown voltage at room temperature at a current density of 10 mA. It was measured.
Figure JPOXMLDOC01-appb-T000002
　表２の結果より、安息香酸アンモニウムの量が１３ｗｔ％では耐電圧が３２０Ｖであったが（実施例９）、１０ｗｔ％で３５０Ｖ（実施例８）、７ｗｔ％で４００Ｖ（実施例７）、３ｗｔ％で４２０Ｖ（実施例６）、１ｗｔ％で４３０Ｖ（実施例５）となり、溶質の安息香酸アンモニウムの量が減少するに従って耐電圧が向上した。
　このため、安息香酸アンモニウムの量を特に１０ｗｔ％以下、特に７ｗｔ％以下とすることにより、耐電圧が飛躍的に向上することが判明した。 From the results in Table 2, the withstand voltage was 320 V when the amount of ammonium benzoate was 13 wt% (Example 9), 350 V (Example 8) at 10 wt%, 400 V at 7 wt% (Example 7), 3 wt. % Was 420 V (Example 6) and 1 wt% was 430 V (Example 5), and the withstand voltage improved as the amount of ammonium benzoate in the solute decreased.
For this reason, it has been found that the withstand voltage is drastically improved by setting the amount of ammonium benzoate to 10 wt% or less, particularly 7 wt% or less.
　更に、表３に示すように、エチレングリコールと安息香酸アンモニウムとの配合比を変化させた実施例１、実施例５～９の電解液を充填した各固体電解コンデンサに関し、ＥＳＲとｔａｎδの初期特性および１５０℃、２０００時間無負荷放置後の特性を評価した。ｔａｎδは１２０Ｈｚにおける値を示している。コンデンサ素子の素子形状は１０φ×１２．５Ｌであり、固体電解コンデンサの定格電圧は１００ＷＶ、定格容量は３３μＦである。
Figure JPOXMLDOC01-appb-T000003
 Furthermore, as shown in Table 3, the initial characteristics of ESR and tan δ are related to the solid electrolytic capacitors filled with the electrolyte solutions of Examples 1 and 5 to 9 in which the blending ratio of ethylene glycol and ammonium benzoate is changed. And the characteristic after leaving unloaded for 150 hours at 150 ° C. was evaluated. Tan δ represents a value at 120 Hz. The element shape of the capacitor element is 10φ × 12.5L, the rated voltage of the solid electrolytic capacitor is 100 WV, and the rated capacity is 33 μF.
Figure JPOXMLDOC01-appb-T000003
　表３の結果より、初期のＥＳＲ及びｔａｎδは実施例１、実施例５～９の全てが同等であったが、１５０℃、２０００時間無負荷放置後については、安息香酸アンモニウムの量が減少するに従って特性劣化の程度が小さくなっている。特に、実施例９に対して実施例１、実施例５～８を比較すると、安息香酸アンモニウムの量を１０ｗｔ％以下とすることにより、特性劣化の程度が著しく小さくなり、また実施例８に対して実施例１、実施例５～７を比較すると、７ｗｔ％以下とすることにより、更に特性劣化の程度が小さくなっていることがわかる。
　このため、安息香酸アンモニウムの量を特に１０ｗｔ％以下、望ましくは７ｗｔ％以下とすることにより、ＥＳＲ及びｔａｎδの特性劣化を更に抑制できることが判明した。
  From the results of Table 3, the initial ESR and tan δ were the same in Example 1 and Examples 5 to 9, but the amount of ammonium benzoate decreased after being left unloaded at 150 ° C. for 2000 hours. Accordingly, the degree of characteristic deterioration is reduced. In particular, when Example 1 and Examples 5 to 8 are compared with Example 9, the amount of ammonium benzoate is reduced to 10 wt% or less, so that the degree of characteristic deterioration is remarkably reduced. Thus, when Example 1 and Examples 5 to 7 are compared, it can be seen that the degree of characteristic deterioration is further reduced by setting it to 7 wt% or less.
For this reason, it has been found that the characteristic deterioration of ESR and tan δ can be further suppressed by setting the amount of ammonium benzoate to 10 wt% or less, preferably 7 wt% or less.

Claims (7)

  1. 　陽極電極箔と陰極電極箔とをセパレータを介して巻回したコンデンサ素子に、導電性高分子の粒子が溶媒に分散した導電性高分子分散体を用いて固体電解質層を形成するとともに、該固体電解質層が形成されたコンデンサ素子内の空隙部に、溶質として芳香族カルボン酸のアンモニウム塩を含有した電解液を充填させたことを特徴とする固体電解コンデンサ。 A solid electrolyte layer is formed using a conductive polymer dispersion in which conductive polymer particles are dispersed in a solvent on a capacitor element in which an anode electrode foil and a cathode electrode foil are wound via a separator, and the solid A solid electrolytic capacitor characterized in that an electrolyte solution containing an ammonium salt of an aromatic carboxylic acid as a solute is filled in a gap in a capacitor element in which an electrolyte layer is formed.
  2. 　前記芳香族カルボン酸は、芳香族モノカルボン酸又は芳香族ヒドロキシモノカルボン酸であることを特徴とする請求項１記載の固体電解コンデンサ。 2. The solid electrolytic capacitor according to claim 1, wherein the aromatic carboxylic acid is an aromatic monocarboxylic acid or an aromatic hydroxymonocarboxylic acid.
  3. 　前記芳香族モノカルボン酸は、安息香酸又はナフトエ酸であることを特徴とする請求項２記載の固体電解コンデンサ。 3. The solid electrolytic capacitor according to claim 2, wherein the aromatic monocarboxylic acid is benzoic acid or naphthoic acid.
  4. 　前記芳香族ヒドロキシモノカルボン酸は、サリチル酸、マンデル酸又はヒドロキシナフトエ酸であることを特徴とする請求項２記載の固体電解コンデンサ。 3. The solid electrolytic capacitor according to claim 2, wherein the aromatic hydroxymonocarboxylic acid is salicylic acid, mandelic acid or hydroxynaphthoic acid.
  5. 　前記電解液の溶媒として多価アルコールを用いることを特徴とする請求項１乃至４のいずれかに記載の固体電解コンデンサ。 5. The solid electrolytic capacitor according to claim 1, wherein a polyhydric alcohol is used as a solvent for the electrolytic solution.
  6. 　前記溶質の濃度が１０ｗｔ％以下であることを特徴とする請求項１乃至５のいずれかに記載の固体電解コンデンサ。 6. The solid electrolytic capacitor according to claim 1, wherein the concentration of the solute is 10 wt% or less.
  7. 　陽極電極箔と陰極電極箔とをセパレータを介して巻回したコンデンサ素子に、導電性高分子の粒子が溶媒に分散した導電性高分子分散体を含浸させて固体電解質層を形成する工程と、該固体電解質層が形成されたコンデンサ素子内の空隙部に、溶質として芳香族カルボン酸のアンモニウム塩を含有した電解液を含浸させる工程と、を有することを特徴とする固体電解コンデンサの製造方法。
          A step of impregnating a capacitor element in which an anode electrode foil and a cathode electrode foil are wound via a separator with a conductive polymer dispersion in which conductive polymer particles are dispersed in a solvent to form a solid electrolyte layer; And a step of impregnating a void in the capacitor element in which the solid electrolyte layer is formed with an electrolytic solution containing an ammonium salt of an aromatic carboxylic acid as a solute.
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JP2020088332A (en) * 2018-11-30 2020-06-04 富山薬品工業株式会社 Electrolyte solution for electrolytic capacitor, and electrolytic capacitor
US11114250B2 (en) 2018-08-10 2021-09-07 Avx Corporation Solid electrolytic capacitor formed from conductive polymer particles
US11183342B2 (en) 2018-08-10 2021-11-23 Avx Corporation Solid electrolytic capacitor containing polyaniline
US11462366B2 (en) 2018-08-10 2022-10-04 KYOCERA AVX Components Corporation Solid electrolytic capacitor containing an intrinsically conductive polymer
US11631548B2 (en) 2020-06-08 2023-04-18 KYOCERA AVX Components Corporation Solid electrolytic capacitor containing a moisture barrier
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JP7210004B2 (en) 2018-11-30 2023-01-23 富山薬品工業株式会社 Electrolyte for electrolytic capacitor and electrolytic capacitor
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