JP2004119830A

JP2004119830A - Manufacturing method of solid electrolytic capacitor

Info

Publication number: JP2004119830A
Application number: JP2002283503A
Authority: JP
Inventors: Norihito Fukui; 福井　典仁
Original assignee: Nippon Chemi Con Corp
Current assignee: Nippon Chemi Con Corp
Priority date: 2002-09-27
Filing date: 2002-09-27
Publication date: 2004-04-15
Anticipated expiration: 2022-09-27
Also published as: JP4363022B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a solid electrolytic capacitor having large electrostatic capacity and capable of reducing equivalent series resistance (ESR). <P>SOLUTION: After a voltage is applied to a valve metal foil treated with etching in a chemical solution, a dielectric oxide film is formed on the surface of the metallic foil and used as a positive electrode, and an etched foil is used as a cathode electrode. The cathode electrode is not treated chemically before winding or lamination. The positive electrode and the cathode electrode are wound or laminated with a separator in between to form a capacitor element. The capacitor element is dipped in a chemical solution. A voltage is applied to the cathode electrode and a repairing chemical treatment is carried out to repair a damaged part of the oxide coating film. After the capacitor element is dried, the capacitor element is impregnated with polymer monomer and oxidant, and a solid electrolytic layer is formed to form the solid electrolytic capacitor. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、固体電解コンデンサの製造方法に係り、特に、等価直列抵抗（以下、ＥＳＲという）の低減を図り、静電容量の大きい固体電解コンデンサの製造方法に関する。
【０００２】
【従来の技術】
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。
【０００３】
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。
【０００４】
また、電解コンデンサの静電容量を高めるために、電極材料の基材であるアルミニウム箔の表面積を、化学的にあるいは電気化学的にエッチングにより拡大することが行われている。
【０００５】
【特許文献１】
特開２０００−１０６３３１号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、上述したような従来の固体電解コンデンサには、以下に述べるような問題点があった。すなわち、従来の固体電解コンデンサにおいては、電解コンデンサの静電容量を高めるために、電極材料の基材であるアルミニウム箔の表面にエッチング処理を施しているが、エッチングが過大になるとアルミニウム箔表面の溶解が同時に進行し、却って拡面率の増大を妨げることなどの理由から、エッチング技術による電極材料の静電容量の増大化には限界があった。
【０００７】
また、従来、固体電解コンデンサの固体電解質には、主に硝酸マンガンの熱分解により形成される二酸化マンガンが用いられていたが、この二酸化マンガンは導電率が比較的高いため、コンデンサとしてのＥＳＲの低減には限度があった。この問題点を解決するため、本出願人は、陰極箔の表面に化成電圧が１０Ｖ以下の化成皮膜を形成するという方法を提案した（特許文献１）。
しかしながら、近年のデジタル機器においては、さらなる低ＥＳＲのコンデンサや静電容量の大きいコンデンサの開発が切望されている。
【０００８】
本発明は、上述したような従来技術の問題点を解決するために提案されたものであり、その目的は、等価直列抵抗（ＥＳＲ）の低減を可能とし、静電容量の大きい固体電解コンデンサの製造方法を提供することにある。
【０００９】
【課題を解決するための手段】
本発明者は、上記課題を解決すべく、ＥＳＲの低減と、静電容量の向上を可能とした固体電解コンデンサの製造方法について鋭意検討を重ねた結果、本発明を完成するに至ったものである。
【００１０】
（固体電解コンデンサの製造方法…その１）
エッチング処理した弁金属箔を化成液中で電圧印加して金属箔表面に誘電体酸化皮膜を形成し、この箔を所定の大きさに切断して陽極体として用いる。また、陰極体にはエッチング箔を用いるが、この陰極体には、巻回又は積層前に化成処理を行わない。そして、このように形成した陽極体と陰極体を、セパレータを介して巻回又は積層してコンデンサ素子を形成した後、このコンデンサ素子を化成液に浸漬して、陰極体に電圧印加して化成を行う。
続いて、陽極体にも電圧印加して修復化成を行い、電極体の切断面や、コンデンサ素子作成工程で損傷を受けた酸化皮膜の損傷部分を修復する。そして、コンデンサ素子を乾燥させた後、コンデンサ素子に重合性モノマーと酸化剤を含浸し、固体電解質層を形成して固体電解コンデンサを形成する。
【００１１】
このようにして形成した固体電解コンデンサにおいては、ＥＳＲ特性が大幅に低減され、かつ静電容量も増加することが判明した。その理由は、陰極体に酸化皮膜を形成した直後に固体電解質を形成することにより、酸化皮膜は良質な状態で、その上に固体電解質層が形成されるため、陰極体と固体電解質層との密着性が向上すると考えられる。
【００１２】
（固体電解コンデンサの製造方法…その２）
エッチング処理した弁金属箔を化成液中で電圧印加して金属箔表面に誘電体酸化皮膜を形成し、この箔を所定の大きさに切断して陽極体として用いる。また、陰極体にはエッチング箔を用いるが、この陰極体には、巻回又は積層前に予め数Ｖで化成処理を行う。このようにして誘電体酸化皮膜が形成された陰極体と陽極体とをセパレータを介して巻回又は積層してコンデンサ素子を形成した後、このコンデンサ素子を化成液に浸漬して、陰極体に電圧印加して化成を行う。
続いて、陽極体にも電圧印加して修復化成を行い、電極体の切断面や、コンデンサ素子作成工程で損傷を受けた酸化皮膜の損傷部分を修復する。そして、コンデンサ素子を乾燥させた後、コンデンサ素子に重合性モノマーと酸化剤を含浸し、固体電解質層を形成して固体電解コンデンサを形成する。
【００１３】
このようにして形成した固体電解コンデンサにおいては、ＥＳＲ特性がさらに改善されることが判明した。その理由は、予め形成されている酸化皮膜層に再度電圧印加して化成を行った直後に固体電解質層を形成することにより、陰極体の酸化皮膜は表面状態が均一に再生された状態で、その上に固体電解質層が形成されるため、陰極体と固体電解質層との密着性が向上するためと考えられる。
【００１４】
（化成電圧）
固体電解質層形成の直前に陰極体に行う化成処理を「第１の化成処理」、巻回又は積層前に陰極体に行う化成処理を「第２の化成処理」と言うこととすると、第１の化成処理の化成電圧は、０．５〜５Ｖが好ましく、また、第２の化成処理の化成電圧は、第１の化成処理の化成電圧以下とすることが望ましい。この第２の化成処理の化成電圧を、第１の化成処理の化成電圧を超える電圧としても、ＥＳＲ特性の改善にはあまり効果は認められなかった。
【００１５】
（陰極体の化成液）
陰極体の化成液としては、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等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。なお、リン酸二水素アンモニウムの水溶液の濃度は、０．００５〜３％が適している。
【００１６】
（ＥＤＴ及び酸化剤）
重合性モノマーとしてＥＤＴを用いた場合、コンデンサ素子に含浸するＥＤＴとしては、ＥＤＴモノマーを用いることができるが、ＥＤＴと揮発性溶媒とを１：０〜１：３の体積比で混合したモノマー溶液を用いることもできる。
前記揮発性溶媒としては、ペンタン等の炭化水素類、テトラヒドロフラン等のエーテル類、ギ酸エチル等のエステル類、アセトン等のケトン類、メタノール等のアルコール類、アセトニトリル等の窒素化合物等を用いることができるが、なかでも、メタノール、エタノール、アセトン等が好ましい。
また、酸化剤としては、ブタノールに溶解したパラトルエンスルホン酸第二鉄、過ヨウ素酸もしくはヨウ素酸の水溶液を用いることができる。
【００１７】
（他の重合性モノマー）
本発明に用いられる重合性モノマーとしては、上記ＥＤＴの他に、ＥＤＴ以外のチオフェン誘導体、アニリン、ピロール、フラン、アセチレンまたはそれらの誘導体であって、所定の酸化剤により酸化重合され、導電性ポリマーを形成するものであれば適用することができる。なお、チオフェン誘導体としては、下記の構造式のものを用いることができる。
【化１】

【００１８】
（作用・効果）
本発明によれば、陽極体と陰極体をセパレータを介して巻回又は積層してコンデンサ素子を形成し、陰極体を化成液中に浸漬して化成処理した後、セパレータに導電性ポリマーを保持させることにより、固体電解コンデンサの電気的特性が改善される。特に、巻回又は積層前に酸化皮膜を形成していない陰極体を用いてコンデンサ素子を形成した後、陰極体に電圧印加して化成処理を行うと、ＥＳＲ特性、静電容量が良好な結果が得られた。また、巻回又は積層前に予め化成により酸化皮膜を形成した陰極体を用いてコンデンサ素子を形成した後、再度電圧印加して陰極体に化成処理を行うと、ＥＳＲ特性がさらに改善される効果が得られる。
【００１９】
【実施例】
続いて、以下のようにして製造した実施例１〜４及び従来例１〜３に基づいて本発明をさらに詳細に説明する。
【００２０】
（実施例１）
（ａ）素子形成工程：エッチングのみのアルミニウム箔からなる陰極体と、エッチング及び酸化皮膜が形成された陽極体を、セパレータを介して巻回してコンデンサ素子を形成した。
（ｂ）化成工程：０．１５％のリン酸二水素アンモニウムを添加した温度５０℃の水溶液に上記のコンデンサ素子を浸漬して、陰極体を化成した。なお、化成電圧は１Ｖ、化成時間は１０分とした。また、陽極体も化成電圧９Ｖで修復化成した。
（ｃ）固体電解質層形成工程：上記のコンデンサ素子にＥＤＴモノマー、４５％パラトルエンスルホン酸第二鉄のブタノール溶液を酸化剤溶液として含浸して、１００℃、一時間加熱した。
（ｄ）ケース収納工程：上記のコンデンサ素子を有底筒状の外装ケースに挿入し、開口端部に封口部材を配して加締め加工により封止した。その後、エージングを行って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４ＷＶである。
【００２１】
（実施例２）
（ａ）素子形成工程：陰極体を、０．１５％のリン酸二水素アンモニウムを添加した温度５０℃の水溶液に浸漬し、化成電圧１Ｖで１０分間化成して予め酸化皮膜を形成し、この陰極体と陽極体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した。
（ｂ）以降の化成工程、固体電解質層形成工程、ケース収納工程は実施例１と同様とした。
【００２２】
（実施例３）
（ａ）素子形成工程：陰極体を、０．１５％のリン酸二水素アンモニウムを添加した温度５０℃の水溶液に浸漬し、化成電圧２Ｖで１０分間化成して予め酸化皮膜を形成し、この陰極体と陽極体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した。
（ｂ）化成工程：０．１５％のリン酸二水素アンモニウムを添加した温度５０℃の水溶液に上記のコンデンサ素子を浸漬して、陰極体を化成した。なお、化成電圧は２Ｖ、化成時間は１０分とした。また、陽極体も化成電圧９Ｖで修復化成した。
（ｃ）以降の工程は実施例１と同様とした。
【００２３】
（実施例４）
（ａ）素子形成工程：陰極体を、０．１５％のリン酸二水素アンモニウムを添加した温度５０℃の水溶液に浸漬し、化成電圧１Ｖで１０分間化成して予め酸化皮膜を形成し、この陰極体と陽極体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した。
（ｂ）化成工程：０．１５％のリン酸二水素アンモニウムを添加した温度５０℃の水溶液に上記のコンデンサ素子を浸漬して、陰極体を化成した。なお、化成電圧は２Ｖ、化成時間は１０分とした。また、陽極体も化成電圧９Ｖで修復化成した。
（ｃ）以降の工程は実施例１と同様とした。
【００２４】
（従来例１）
（ａ）素子形成工程：エッチング処理のみのアルミニウム箔からなる陰極体と、エッチング及び酸化皮膜が形成された陽極体を、セパレータを介して巻回してコンデンサ素子を形成した。
（ｂ）化成工程：陽極体のみ化成電圧９Ｖで修復化成し、陰極体は化成を行っていない。
（ｃ）以降の工程は実施例１と同様とした。
【００２５】
（従来例２）
（ａ）素子形成工程：陰極体を、０．１５％のリン酸二水素アンモニウムを添加した温度５０℃の水溶液に浸漬し、化成電圧１Ｖで１０分間化成して予め酸化皮膜を形成し、この陰極体と陽極体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した。
（ｂ）以降の工程は従来例１と同様とした。
【００２６】
（従来例３）
（ａ）素子形成工程：陰極体を、０．１５％のリン酸二水素アンモニウムを添加した温度５０℃の水溶液に浸漬し、化成電圧２Ｖで１０分間化成して予め酸化皮膜を形成し、この陰極体と陽極体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した。
（ｂ）以降の工程は従来例１と同様とした。
【００２７】
［比較結果１］
まず、陰極体の巻回前に予め化成を行っていない場合、すなわち、実施例１と従来例１とを比較したところ、表１のような結果が得られた。
【表１】

【００２８】
実施例１及び従来例１は、共に、コンデンサ素子の巻回前には化成処理を行っていないが、コンデンサ素子の形成後に陰極体に電圧印加して化成を行った実施例１においては、ＥＳＲ特性及び静電容量共に良好な結果が得られた。
【００２９】
［比較結果２］
次に、陰極体の巻回前に、化成電圧１Ｖで予め化成を行った場合、すなわち、実施例２、実施例４及び従来例２を比較したところ、表２のような結果が得られた。
【表２】

【００３０】
実施例２、実施例４及び従来例２は、共に、コンデンサ素子の巻回前に化成電圧１Ｖで化成処理を行い、酸化皮膜を形成したものであるが、さらに、コンデンサ素子の形成後に再度陰極体に電圧印加して化成を行った実施例２及び実施例４においては、ＥＳＲ特性は従来例２より良好な結果が得られた。
【００３１】
また、実施例２と実施例４を比較すると、再度化成する際の電圧、すなわち、固体電解質層形成前の陰極体の化成電圧の違いによる差は認められなかった。このことから、再度化成する際の電圧を、巻回前に予め行った化成電圧より大きくしても、ＥＳＲ特性に効果は認められないことが分かった。
【００３２】
［比較結果３］
さらに、陰極体の巻回前に、化成電圧２Ｖで予め化成を行った場合、すなわち、実施例３及び従来例３を比較したところ、表３のような結果が得られた。
【表３】

【００３３】
実施例３及び従来例３は、共に、コンデンサ素子の巻回前に化成電圧２Ｖで化成処理を行い、酸化皮膜を形成したものであるが、さらに、コンデンサ素子の形成後に陰極体に電圧印加して化成を行った実施例３は、従来例３と比較して、ＥＳＲ特性に良好な結果が得られた。
【００３４】
【発明の効果】
以上述べたように、本発明によれば、固体電解質層の形成前に、陰極体の表面に化成皮膜を形成することにより、あるいは、さらに、陰極体と陽極体を巻回又は積層する前に、予め陰極体の表面に化成皮膜を形成することにより、等価直列抵抗（ＥＳＲ）の低減を可能とし、静電容量の大きい固体電解コンデンサの製造方法を提供することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a solid electrolytic capacitor, and more particularly, to a method for manufacturing a solid electrolytic capacitor having a large capacitance, which reduces equivalent series resistance (hereinafter, referred to as ESR).
[0002]
[Prior art]
Electrolytic capacitors using a metal having a valve action, such as tantalum or aluminum, have a valve action metal as an anode-side counter electrode, which is formed by sintering or etching foil or the like to enlarge the dielectric, Since it is small and can obtain a large capacity, it is widely and generally used. In particular, a solid electrolytic capacitor using a solid electrolyte as an electrolyte has characteristics such as being small, 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 devices.
[0003]
In this type of solid electrolytic capacitor, for small-sized and large-capacity applications, generally, an anode foil and a cathode foil made of valve metal such as aluminum are wound with a separator interposed therebetween to form a capacitor element. It has a structure in which a capacitor element is housed in a case made of a metal such as aluminum or a case made of a synthetic resin, impregnated with a driving electrolyte, and sealed. Note that as the anode material, aluminum, tantalum, niobium, titanium, or the like is used, and as the cathode material, the same kind of metal as the anode material is used.
[0004]
Further, in order to increase the capacitance of an electrolytic capacitor, the surface area of an aluminum foil, which is a base material of an electrode material, is enlarged chemically or electrochemically by etching.
[0005]
[Patent Document 1]
JP 2000-106331 A
[Problems to be solved by the invention]
However, the conventional solid electrolytic capacitors as described above have the following problems. That is, in the conventional solid electrolytic capacitor, the surface of the aluminum foil, which is the base material of the electrode material, is etched to increase the capacitance of the electrolytic capacitor. There has been a limit to the increase in the capacitance of the electrode material by the etching technique, for example, because the melting proceeds at the same time and the increase in the area coverage is rather hindered.
[0007]
Conventionally, as a solid electrolyte of a solid electrolytic capacitor, manganese dioxide formed mainly by thermal decomposition of manganese nitrate has been used. However, since this manganese dioxide has a relatively high conductivity, the ESR of the capacitor as a capacitor is low. The reduction was limited. In order to solve this problem, the present applicant has proposed a method of forming a chemical conversion film having a formation voltage of 10 V or less on the surface of a cathode foil (Patent Document 1).
However, in digital devices in recent years, there has been a strong demand for the development of a capacitor having a lower ESR and a capacitor having a larger capacitance.
[0008]
The present invention has been proposed in order to solve the problems of the prior art as described above, and an object of the present invention is to reduce the equivalent series resistance (ESR) of a solid electrolytic capacitor having a large capacitance. It is to provide a manufacturing method.
[0009]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on a method of manufacturing a solid electrolytic capacitor capable of reducing the ESR and improving the capacitance in order to solve the above problems, and as a result, have completed the present invention. is there.
[0010]
(Manufacturing method of solid electrolytic capacitor ... Part 1)
A voltage is applied to the etched valve metal foil in a chemical conversion solution to form a dielectric oxide film on the surface of the metal foil, and this foil is cut into a predetermined size and used as an anode body. Further, although an etching foil is used for the cathode body, the cathode body is not subjected to a chemical conversion treatment before winding or lamination. Then, the anode body and the cathode body formed as described above are wound or laminated with a separator interposed therebetween to form a capacitor element. Then, the capacitor element is immersed in a chemical solution and a voltage is applied to the cathode body to form a capacitor. I do.
Subsequently, a repair chemical conversion is performed by applying a voltage to the anode body to repair the cut surface of the electrode body and the damaged portion of the oxide film damaged in the capacitor element forming process. After drying the capacitor element, the capacitor element is impregnated with a polymerizable monomer and an oxidizing agent to form a solid electrolyte layer to form a solid electrolytic capacitor.
[0011]
It has been found that in the solid electrolytic capacitor thus formed, the ESR characteristics are significantly reduced and the capacitance is also increased. The reason is that by forming the solid electrolyte immediately after forming the oxide film on the cathode body, the oxide film is in a good state, and the solid electrolyte layer is formed thereon, so that the cathode body and the solid electrolyte layer It is considered that the adhesion is improved.
[0012]
(Method of manufacturing solid electrolytic capacitor ... Part 2)
A voltage is applied to the etched valve metal foil in a chemical conversion solution to form a dielectric oxide film on the surface of the metal foil, and this foil is cut into a predetermined size and used as an anode body. Further, an etching foil is used for the cathode body, and the cathode body is subjected to a chemical treatment at several V in advance before winding or lamination. The capacitor element is formed by winding or laminating the cathode body and the anode body on which the dielectric oxide film has been formed in this way via a separator, and then immersing the capacitor element in a chemical solution to form a cathode body. The formation is performed by applying a voltage.
Subsequently, a repair chemical conversion is performed by applying a voltage to the anode body to repair the cut surface of the electrode body and the damaged portion of the oxide film damaged in the capacitor element forming process. After drying the capacitor element, the capacitor element is impregnated with a polymerizable monomer and an oxidizing agent to form a solid electrolyte layer to form a solid electrolytic capacitor.
[0013]
It has been found that in the solid electrolytic capacitor thus formed, the ESR characteristics are further improved. The reason is that the oxide film of the cathode body is uniformly regenerated by forming the solid electrolyte layer immediately after applying a voltage again to the oxide film layer formed in advance and forming the solid electrolyte layer. It is considered that since the solid electrolyte layer is formed thereon, the adhesion between the cathode body and the solid electrolyte layer is improved.
[0014]
(Formation voltage)
The chemical conversion treatment performed on the cathode body immediately before the formation of the solid electrolyte layer is referred to as “first chemical conversion treatment”, and the chemical conversion treatment performed on the cathode body before winding or lamination is referred to as “second chemical conversion treatment”. The formation voltage of the formation process is preferably 0.5 to 5 V, and the formation voltage of the second formation process is desirably equal to or lower than the formation voltage of the first formation process. Even if the formation voltage of the second chemical treatment was set to a voltage exceeding the formation voltage of the first chemical treatment, no significant effect was observed on the improvement of the ESR characteristics.
[0015]
(Chemical solution of cathode body)
As the chemical liquid for the cathode body, a phosphoric acid-based chemical such as ammonium dihydrogen phosphate and diammonium hydrogen phosphate, a boric acid-based chemical such as ammonium borate, and an adipic acid-based chemical such as ammonium adipate are used. Although a liquid or the like can be used, it is preferable to use ammonium dihydrogen phosphate. In addition, the concentration of the aqueous solution of ammonium dihydrogen phosphate is suitably 0.005 to 3%.
[0016]
(EDT and oxidizing agent)
When EDT is used as the polymerizable monomer, an EDT monomer can be used as the EDT to be impregnated in the capacitor element, but a monomer solution in which EDT and a volatile solvent are mixed at a volume ratio of 1: 0 to 1: 3. Can also be used.
As the volatile solvent, hydrocarbons such as pentane, ethers such as tetrahydrofuran, esters such as ethyl formate, ketones such as acetone, alcohols such as methanol, and nitrogen compounds such as acetonitrile can be used. However, among them, methanol, ethanol, acetone and the like are preferable.
As the oxidizing agent, an aqueous solution of ferric paratoluenesulfonate, periodic acid or iodic acid dissolved in butanol can be used.
[0017]
(Other polymerizable monomers)
Examples of the polymerizable monomer used in the present invention include, in addition to the above-mentioned EDT, thiophene derivatives other than EDT, aniline, pyrrole, furan, acetylene or derivatives thereof, which are oxidatively polymerized by a predetermined oxidizing agent, and Can be applied as long as it forms. As the thiophene derivative, one having the following structural formula can be used.
Embedded image

[0018]
(Action / Effect)
According to the present invention, a capacitor element is formed by winding or laminating an anode body and a cathode body via a separator, and the cathode body is immersed in a chemical conversion solution and subjected to a chemical conversion treatment, and then the separator holds the conductive polymer. By doing so, the electrical characteristics of the solid electrolytic capacitor are improved. In particular, after forming a capacitor element using a cathode body without an oxide film formed before winding or lamination, applying a voltage to the cathode body and performing a chemical conversion treatment results in good ESR characteristics and capacitance. was gotten. Also, when a capacitor element is formed using a cathode body on which an oxide film is formed in advance by chemical conversion before winding or lamination, a voltage is again applied to the cathode body to perform a chemical conversion treatment, whereby the ESR characteristics are further improved. Is obtained.
[0019]
【Example】
Subsequently, the present invention will be described in more detail based on Examples 1 to 4 and Conventional Examples 1 to 3 manufactured as follows.
[0020]
(Example 1)
(A) Element forming step: A capacitor element was formed by winding a cathode body made of an aluminum foil that had only been etched and an anode body having an etched and oxide film formed thereon through a separator.
(B) Chemical conversion step: The above-described capacitor element was immersed in an aqueous solution at a temperature of 50 ° C. to which 0.15% ammonium dihydrogen phosphate was added to form a cathode body. The formation voltage was 1 V and the formation time was 10 minutes. The anode body was also repair-formed at a formation voltage of 9V.
(C) Step of forming solid electrolyte layer: The above capacitor element was impregnated with a butanol solution of EDT monomer and 45% ferric paratoluenesulfonate as an oxidizing agent solution, and heated at 100 ° C. for 1 hour.
(D) Case storage step: The above-described capacitor element was inserted into a bottomed cylindrical outer case, and a sealing member was disposed at the opening end, and the case was sealed by caulking. Thereafter, aging was performed to form a solid electrolytic capacitor. The rated voltage of this solid electrolytic capacitor is 4 WV.
[0021]
(Example 2)
(A) Element formation step: The cathode body was immersed in an aqueous solution at a temperature of 50 ° C. to which 0.15% ammonium dihydrogen phosphate was added, and formed at a formation voltage of 1 V for 10 minutes to form an oxide film in advance. The cathode body and the anode body were wound via a separator to form a capacitor element.
(B) The subsequent chemical conversion step, solid electrolyte layer forming step, and case housing step were the same as in Example 1.
[0022]
(Example 3)
(A) Element formation step: The cathode body was immersed in an aqueous solution at a temperature of 50 ° C. to which 0.15% ammonium dihydrogen phosphate was added, and formed at a formation voltage of 2 V for 10 minutes to form an oxide film in advance. The cathode body and the anode body were wound via a separator to form a capacitor element.
(B) Chemical conversion step: The above-described capacitor element was immersed in an aqueous solution at a temperature of 50 ° C. to which 0.15% ammonium dihydrogen phosphate was added to form a cathode body. The formation voltage was 2 V and the formation time was 10 minutes. The anode body was also repair-formed at a formation voltage of 9V.
(C) The subsequent steps were the same as in Example 1.
[0023]
(Example 4)
(A) Element formation step: The cathode body was immersed in an aqueous solution at a temperature of 50 ° C. to which 0.15% ammonium dihydrogen phosphate was added, and formed at a formation voltage of 1 V for 10 minutes to form an oxide film in advance. The cathode body and the anode body were wound via a separator to form a capacitor element.
(B) Chemical conversion step: The above-described capacitor element was immersed in an aqueous solution at a temperature of 50 ° C. to which 0.15% ammonium dihydrogen phosphate was added to form a cathode body. The formation voltage was 2 V and the formation time was 10 minutes. The anode body was also repair-formed at a formation voltage of 9V.
(C) The subsequent steps were the same as in Example 1.
[0024]
(Conventional example 1)
(A) Element forming step: A capacitor element was formed by winding a cathode body made of an aluminum foil subjected to only an etching treatment and an anode body having an etched and oxide film formed thereon through a separator.
(B) Chemical conversion step: Only the anode body was repaired and formed at a formation voltage of 9 V, and the cathode body was not formed.
(C) The subsequent steps were the same as in Example 1.
[0025]
(Conventional example 2)
(A) Element formation step: The cathode body was immersed in an aqueous solution at a temperature of 50 ° C. to which 0.15% ammonium dihydrogen phosphate was added, and formed at a formation voltage of 1 V for 10 minutes to form an oxide film in advance. The cathode body and the anode body were wound via a separator to form a capacitor element.
(B) The subsequent steps were the same as in Conventional Example 1.
[0026]
(Conventional example 3)
(A) Element formation step: The cathode body was immersed in an aqueous solution at a temperature of 50 ° C. to which 0.15% ammonium dihydrogen phosphate was added, and formed at a formation voltage of 2 V for 10 minutes to form an oxide film in advance. The cathode body and the anode body were wound via a separator to form a capacitor element.
(B) The subsequent steps were the same as in Conventional Example 1.
[0027]
[Comparison result 1]
First, when the chemical conversion was not performed before the winding of the cathode body, that is, when Example 1 and Conventional Example 1 were compared, the results shown in Table 1 were obtained.
[Table 1]

[0028]
In both Example 1 and Conventional Example 1, no chemical conversion treatment was performed before the winding of the capacitor element. However, in Example 1, in which a voltage was applied to the cathode body after formation of the capacitor element, the chemical conversion treatment was performed. Good characteristics and capacitance were obtained.
[0029]
[Comparison result 2]
Next, before the cathode body was wound, when the formation was performed in advance at a formation voltage of 1 V, that is, when Example 2, Example 4, and Conventional Example 2 were compared, the results shown in Table 2 were obtained. .
[Table 2]

[0030]
In each of Example 2, Example 4 and Conventional Example 2, a chemical conversion treatment was performed at a chemical conversion voltage of 1 V before winding of the capacitor element, and an oxide film was formed. In Examples 2 and 4 in which a chemical was applied by applying a voltage to the body, better results were obtained in ESR characteristics than in Conventional Example 2.
[0031]
Further, when Example 2 and Example 4 were compared, no difference due to the difference in the voltage at the time of the formation again, that is, the formation voltage of the cathode body before the formation of the solid electrolyte layer was not recognized. From this, it was found that even if the voltage at the time of formation again was higher than the formation voltage previously performed before winding, no effect was observed on the ESR characteristics.
[0032]
[Comparison result 3]
Furthermore, when the formation was performed at a formation voltage of 2 V before the cathode body was wound, that is, when Example 3 and Conventional Example 3 were compared, the results shown in Table 3 were obtained.
[Table 3]

[0033]
In both Example 3 and Conventional Example 3, a chemical conversion treatment was performed at a formation voltage of 2 V before winding of the capacitor element to form an oxide film, and further, a voltage was applied to the cathode body after the capacitor element was formed. In Example 3 in which chemical conversion was performed, better results were obtained in ESR characteristics as compared with Conventional Example 3.
[0034]
【The invention's effect】
As described above, according to the present invention, before forming the solid electrolyte layer, by forming a chemical conversion film on the surface of the cathode body, or, further, before winding or laminating the cathode body and the anode body By previously forming a chemical conversion film on the surface of the cathode body, it is possible to reduce the equivalent series resistance (ESR) and provide a method of manufacturing a solid electrolytic capacitor having a large capacitance.

Claims

A first chemical conversion in which a capacitor element is formed by winding or laminating a cathode body made of a valve metal and an anode body made of a valve metal having an oxide film formed on its surface, and forming a chemical conversion film on the surface of the cathode body. A method for producing a solid electrolytic capacitor, comprising, after performing a treatment, impregnating a polymerizable monomer and an oxidizing agent to form a solid electrolyte layer made of a conductive polymer.

2. The solid electrolytic capacitor according to claim 1, wherein a second chemical conversion treatment for forming a chemical conversion film is performed before winding or laminating the cathode body and the anode body on the surface of the cathode body. Method.

3. The method according to claim 2, wherein a formation voltage of the second chemical conversion treatment is equal to or less than a formation voltage of the first chemical conversion treatment. 4.

4. The method according to claim 1, wherein the polymerizable monomer is a thiophene derivative. 5.

The method according to claim 4, wherein the thiophene derivative is 3,4-ethylenedioxythiophene.