JP3831752B2

JP3831752B2 - Manufacturing method of solid electrolytic capacitor

Info

Publication number: JP3831752B2
Application number: JP30240999A
Authority: JP
Inventors: 和芳遠藤
Original assignee: Nippon Chemi Con Corp
Current assignee: Nippon Chemi Con Corp
Priority date: 1999-10-25
Filing date: 1999-10-25
Publication date: 2006-10-11
Anticipated expiration: 2019-10-25
Also published as: JP2001126963A

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関する。
【０００２】
【従来の技術】
近年、低ＥＳＲ化を目的として導電性高分子を固体電解質として用いる固体電解コンデンサが実用化されている。一般に、これら導電性高分子としては、ポリチオフェン，ポリピロール又はポリアニリン等があり、中でもポリチオフェンは、ポリピロール又はポリアニリンと比較して導電率が高く熱安定性が特に優れていることから近年注目されており、ポリチオフェンを固体電解質として用いた固体電解コンデンサとして特開平２−１５６１１号公報等に開示されているものがある。
【０００３】
しかして、ポリチオフェンは、化学酸化重合及び電解重合によって製作できるが、電解重合手段を講じた場合、導電性高分子が電極上にフィルム状に形成されるため大量に製造することに困難性が伴う問題を抱えているのに対して、化学酸化重合手段の場合は、そのような問題はなく、電解重合と比較して大量の導電性高分子層を容易に得ることができることは当業者の中では良く知られている。
【０００４】
【発明が解決しようとする課題】
しかしながら、ポリチオフェンは、他のポリピロール又はポリアニリン等他の導電性高分子に比べて化学酸化重合の際の重合速度が小さいため、所望の厚さの導電性高分子層を形成するためには、重合時間を長くしたり、重合回数を多くしなければならず、生産性が悪く、コスト高となる問題を抱え、また、溶媒に水を用いた場合は重合反応が著しく抑制される問題を有し、更に、トランスファーモールド法による樹脂外装構造では、モールド成型時の応力により導電性高分子層が損傷され漏れ電流増大や信頼性低下となる問題をも抱える結果となっていた。
【０００５】
本発明は、上記問題を解決するもので、コンデンサ素子表面に均一な厚さで所望の厚みを有し、機械的強度に優れた導電性高分子層を形成した特性良好にして生産性に優れた固体電解コンデンサの製造方法を提供することを目的とするものである。
【０００６】
【課題を解決するための手段】
本発明は、上記従来技術の課題を解決すべく検討した結果、完成するに至ったものである。すなわち、固体電解質として導電性高分子層を用いた固体電解コンデンサの製造方法において、タンタル焼結体からなるコンデンサ素子表面に形成するポリチオフェン又はその誘導体からなる導電性高分子層を、コンデンサ素子表面に付着したパルプ及び抄紙用粘剤を取り込んで形成した複合導電性高分子層とすることによって、機械的強度に優れた固体電解質の形成が可能となり、作業性良好にして特性劣化のないことが判明した。
【０００７】
本発明は、陽極となる弁作用金属からなる素体表面に誘電体酸化皮膜を形成してなるコンデンサ素子と、前記誘電体酸化皮膜の表面に形成した導電性高分子層からなる固体電解コンデンサの製造方法において、コンデンサ素子表面に形成される導電性高分子層がポリチオフェン又はその誘導体からなり、コンデンサ素子表面に付着したパルプ及び抄紙用粘剤を取り込んで形成した複合導電性高分子層で構成されたことを特徴とする。
【０００８】
また抄紙用粘剤が、とろろ葵，糊空木といった天然糊、又は、ポリエチレンオキシド，ポリアクリルアミドといった合成糊からなることを特徴とする。
【００１０】
こうした導電性高分子層とパルプ及び抄紙用粘剤との複合導電性高分子層を構成する手段としては、パルプを懸濁した水溶液内にタンタル焼結体からなるコンデンサ素子を浸漬後、乾燥させてこのコンデンサ素子表面にパルプを付着させ、次にモノマー溶液に浸漬した後、酸化剤溶液に浸漬し化学酸化重合する固体電解コンデンサの製造方法において、パルプを懸濁した水溶液を作製する際、抄紙用粘剤を加えパルプを分散させることによる。
【００１１】
ここで、パルプを懸濁している溶液は、撹拌され、パルプが静かに流動していても良い。
【００１２】
さらに、前述の手段において、コンデンサ素子に予め導電性高分子層を形成しておくことによって、より緻密で強固な複合導電性高分子層が得られるものである。
【００１３】
導電性高分子と、パルプ及び抄紙用粘剤との複合体を構成することにより、パルプ及び抄紙用粘剤で厚さを稼ぎ、重合時間及び回数を低減して生産性を上げると共に、コンデンサ素子表面に均一で厚い導電性高分子層が形成でき、機械的強度が向上し、樹脂外装時の応力にも耐え、漏れ電流増大や信頼性低下のない良好な固体電解コンデンサを得ることができる。
【００１４】
【発明の実施の形態】
本発明は、陽極となるタンタル焼結体からなる素体表面に誘電体酸化皮膜を形成してなるコンデンサ素子と、前記誘電体酸化皮膜の表面に形成した導電性高分子層からなる固体電解コンデンサの製造方法において、コンデンサ素子表面に形成される導電性高分子層がポリチオフェン又はその誘導体からなり、コンデンサ素子表面に付着したパルプ及び抄紙用粘剤を取り込んで形成した複合導電性高分子層で構成されたことを特徴とする。
【００１５】
なお、コンデンサ素子構成としては、微粉末焼結体形また、誘電体酸化皮膜の形成手段としても特別なものに限定することなく、公知の手段にて行うものである。
【００１６】
コンデンサ素子表面に付着したパルプ及び抄紙用粘剤の存在で膜厚の厚い複合導電性高分子層となることにより、重合回数及び重合時間を低減でき生産性向上に寄与することができる。また複合導電性高分子層は機械的強度が向上するため樹脂外装時の応力にも耐え、漏れ電流増大や信頼性低下のない良好な固体電解コンデンサが得られる。
【００１７】
本発明は、抄紙用粘剤がとろろ葵，糊空木といった天然糊、又は、ポリエチレンオキシド，ポリアクリルアミドといった合成糊からなることを特徴とし、０．０１〜０．１％の濃度で使用されることで均一に且つ少ない回数で所望のパルプ層形成ができ、生産性向上及び諸特性向上に大きく貢献する。
【００１８】
また、コンデンサ素子の表面に付着するパルプからなり、特に十分に叩解されたパルプはフィブリルが発達し、コンデンサ素子の凹凸に絡まりパルプ層の形成が容易となる。また、付着するパルプの厚み確保を容易にするため、叩解が不十分で繊維が長く太いパルプと十分に叩解が進んだパルプとを混合したり、パルプの懸濁液濃度を適宜選択することもできる。
【００１９】
請求項１記載の発明は、パルプを懸濁した水溶液内にタンタル焼結体からなるコンデンサ素子を浸漬後、乾燥させてこのコンデンサ素子表面にパルプを付着させ、次にモノマー溶液に浸漬した後、酸化剤溶液に浸漬し化学酸化重合する固体電解コンデンサの製造方法において、パルプを懸濁した水溶液が、抄紙用粘剤を加えパルプを分散させたことを特徴とする固体電解コンデンサの製造方法であり、パルプを懸濁する水溶液に抄紙用粘剤が加えられることにより、所望のパルプ層形成が容易となり生産性向上及び諸特性向上に大きく貢献する。
【００２０】
請求項２記載の発明は、コンデンサ素子に予め導電性高分子層を形成しておき、次いでパルプを懸濁した水溶液内にコンデンサ素子を浸漬後、乾燥させてこのコンデンサ素子表面にパルプを付着させ、次にモノマー溶液に浸漬した後、酸化剤溶液に浸漬し化学酸化重合する固体電解コンデンサの製造方法において、パルプを懸濁した水溶液が、抄紙用粘剤を加えパルプを分散させたことを特徴とする固体電解コンデンサの製造方法であり、コンデンサ素子内部への導電性高分子層の形成が容易となり生産性向上及び諸特性向上に大きく貢献する。
【００２１】
本発明は以上のように、電解質としての複合導電性高分子層を形成した後、必要に応じて乾燥を行い、公知の手段でその上にグラファイト層、銀塗料層を形成し、しかる後引出電極を設けて樹脂外装を施し完成品としてなるものである。
【００２２】
【実施例】
以下、本発明の固体電解コンデンサの基本構造について図面を参照して説明する。図１において、１は陽極となる弁作用金属としてタンタル微粉末からなる焼結体表面に陽極酸化皮膜を形成してなるコンデンサ素子で、２はこのコンデンサ素子１の表面に付着したパルプ及び抄紙用粘剤３を取り込んで形成された複合導電性高分子層で、４はこの複合導電性高分子層２上に形成したカーボン層で、５はこのカーボン層４上に形成した陰極となる銀塗料層で、６は前記焼結体に埋設された陽極線で、７はこの陽極線６と接続した陽極引出端子で、８は前記銀塗料層５に接続した陰極引出端子で、９は樹脂外装層である。
【００２３】
次に具体的な実施例について比較例と対比して詳細に説明する。すなわち、以下に示す実施例１〜４及び従来技術に係る比較例１，２の容量、漏れ電流及びＥＳＲ特性を測定した結果、表１に示す通りであった。
【００２４】
（実施例１）陽極として大きさが３．９×３．３×１．６ｍｍ３のタンタル焼結体を用い、陽極線としてタンタル線を用いた重量が約１００ｍｇの陽極体を０．０５ｗｔ％燐酸水溶液中で９０℃、４０Ｖで１８０分陽極酸化し、脱イオン水の流水により洗浄して、乾燥を行いコンデンサ素子とした。なお、この状態をコンデンサと見立て化成液中の容量を測定した結果１００μＦであった。
【００２５】
次に、このコンデンサ素子をブチルアルコール５０ｇと３，４−エチレンジオキシチオフェン５０ｇとを混ぜ合わせてなるモノマー溶液に７分間浸漬し、次に遷移金属イオンを含む酸化剤としてパラトルエンスルホン酸第二鉄４０ｇを６０ｇのブタノールに溶解させて得た酸化剤溶液に１５分間浸漬し、化学酸化重合を行い、コンデンサ素子を構成する陽極酸化皮膜上に導電性高分子層を形成し、ブタノールによる洗浄を５分間行った後、１０５℃で５分間乾燥した。導電性高分子層が所望の厚さになるまで、モノマー溶液への浸漬−乾燥までの重合回数を１０回繰り返した。
【００２６】
次に、このようにして導電性高分子層を形成したコンデンサ素子を、パルプ２ｗｔ％，合成糊０．０５ｗｔ％懸濁液に浸漬してコンデンサ素子表面にパルプを付着させる。この場合、懸濁液は撹拌され、パルプが流動している中に浸漬することで効果的にコンデンサ素子表面へのパルプの付着を行うことができ、特に機械的強度が求められるコンデンサ素子エッジ部により効果的に付着できる。しかして、このようにパルプを付着したコンデンサ素子を１０５℃で５分間乾燥した。なお、パルプ層が所望の厚さになるまで、懸濁液への浸漬から乾燥までの工程を２回繰り返した。
【００２７】
次に、表面にパルプが付着されたコンデンサ素子を、再びモノマー溶液に７分間浸漬して酸化剤溶液に１５分間浸漬して化学酸化重合を行い、ブタノールによる洗浄を５分間行った後、１０５℃で５分間乾燥する工程を５回繰り返し、コンデンサ素子表面に所望の厚さのパルプを取り込んだ複合導電性高分子層を形成した。しかして、この複合導電性高分子層の上に、カーボン層、このカーボン層の上に陰極となる銀塗料層を形成し、この銀塗料層の上に陰極引出端子を、前記陽極体から引出した陽極線に陽極引出端子をそれぞれ取付け、トランスファーモールドにより樹脂外装を行い、前記陰極引出端子及び陽極引出端子を所定の位置に折曲げてチップ状の固体電解コンデンサを完成した。
【００２８】
（実施例２）実施例１と同様の手段で内部に導電性高分子層を形成したコンデンサ素子を、実施例１と同様の手段でコンデンサ素子にパルプを付着させる。なお、パルプが所望の厚さになるまで、懸濁液への浸漬から乾燥までの工程を８回繰り返した。次に、表面にパルプが付着されたコンデンサ素子に複合導電性高分子層を形成し完成品としてなるものであるが、その手段は実施例１同様である。
【００２９】
（実施例３）実施例１と同様の手段で形成したコンデンサ素子を、実施例１と同様の手段でコンデンサ素子表面にパルプを付着させる。なお、パルプ層が所望の厚さになるまで、懸濁液への浸漬から乾燥までの工程を２回繰り返した。
【００３０】
次に、表面にパルプが付着されたコンデンサ素子を、実施例１と同様の手段で、モノマー溶液に７分間浸漬して酸化剤溶液に１５分間浸漬し化学酸化重合を行い、ブタノールによる流水洗浄を５分間行った後、１０５℃で５分間乾燥する工程を１５回繰り返し、コンデンサ素子表面に所望の厚さのパルプを取り込んだ複合導電性高分子層を形成した。しかして、実施例１と同様の手段でチップ状の固体電解コンデンサを完成した。
【００３１】
（実施例４）実施例３と同様の手段で形成したコンデンサ素子を、実施例１と同様の手段でコンデンサ素子表面にパルプを付着させる。なお、パルプ層が所望の厚さになるまで、懸濁液への浸漬から乾燥までの工程を８回繰り返した。
【００３２】
次に、表面にパルプが付着されたコンデンサ素子を、実施例３と同様の手段で、複合導電性高分子層を形成した。また、複合導電性高分子層形成後、完成品としてなるまでの手段は実施例３と同様である。
【００３３】
（比較例１）コンデンサ素子表面へパルプを付着する工程を除き、実施例１と同様の工程を経て完成品としてなるものであるが、コンデンサ素子表面へパルプが付着されていないため、コンデンサ素子表面の導電性高分子層構成は、パルプとの複合化はされておらず、単なる導電性高分子層であり、この場合の重合回数は６１回である。
【００３４】
（比較例２）重合回数を１５回とする点を除き、比較例１と同様の工程を経て完成したものである。
【００３５】
【表１】

【００３６】
表１から明らかなように、実施例１，２，３，４のものは、いずれも漏れ電流及びＥＳＲ特性に優れ信頼性の高い固体電解コンデンサを得ることができるのに対し、比較例１，２のものはＥＳＲ特性は問題ないものの、重合回数を比較例１のように６１回行っても漏れ電流特性が芳しくなく実用上好ましくないものであることが分かる。この差は実施例の場合、コンデンサ素子表面に形成される導電性高分子層が、パルプ及び抄紙用粘剤を取り込んだ複合導電性高分子層で構成されてその層厚を稼げるため、導電性高分子層の機械的強度を高めることになり、外装樹脂工程での応力によっても導電性高分子層を損傷することがないと言う結果に基づくものである。また、比較例の中で、漏れ電流特性が最もよい比較例１においても６１回の重合回数を要し、生産性の観点からも好ましくないのに対し、実施例のものは、重合回数を減らしても漏れ電流特性が優れており、生産性向上に大きく貢献できるものであることが分かる。
【００３７】
【発明の効果】
以上述べたように本発明によれば、弁作用金属からなるコンデンサ素子を構成する酸化皮膜の表面に導電性高分子層を形成してなる固体電解コンデンサの製造方法において、導電性高分子層をコンデンサ素子表面に付着したパルプ及び抄紙用粘剤を取り込んで形成した複合導電性高分子層とすることによって、導電性高分子層の層厚を稼ぎ、重合回数を低減して生産性向上を可能とした漏れ電流特性の良好な固体電解コンデンサを得ることができる。
【図面の簡単な説明】
【図１】本発明の固体電解コンデンサの基本構造を示す断面図である。
【符号の説明】
１コンデンサ素子
２複合導電性高分子層
３パルプ
４カーボン層
５銀塗料層
６陽極線
７陽極引出端子
８陰極引出端子
９外装樹脂層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a solid electrolytic capacitor.
[0002]
[Prior art]
In recent years, solid electrolytic capacitors using a conductive polymer as a solid electrolyte have been put into practical use for the purpose of lowering ESR. In general, these conductive polymers include polythiophene, polypyrrole, polyaniline, etc., among which polythiophene has attracted attention in recent years because of its particularly high electrical conductivity and thermal stability compared to polypyrrole or polyaniline, As a solid electrolytic capacitor using polythiophene as a solid electrolyte, there is one disclosed in JP-A-2-15611.
[0003]
Polythiophene can be manufactured by chemical oxidative polymerization and electrolytic polymerization. However, when an electropolymerization means is used, a conductive polymer is formed in a film on the electrode, which makes it difficult to manufacture in large quantities. In the case of chemical oxidative polymerization means, there is no such problem, and it is among those skilled in the art that a large amount of conductive polymer layer can be easily obtained as compared with electrolytic polymerization. Well known.
[0004]
[Problems to be solved by the invention]
However, since polythiophene has a lower polymerization rate during chemical oxidative polymerization than other conductive polymers such as other polypyrrole or polyaniline, polymerization is necessary to form a conductive polymer layer with a desired thickness. There is a problem that the time must be lengthened or the number of times of polymerization must be increased, the productivity is poor and the cost is high, and when water is used as a solvent, the polymerization reaction is remarkably suppressed. Furthermore, the resin exterior structure by the transfer molding method has a problem that the conductive polymer layer is damaged by stress at the time of molding, resulting in an increase in leakage current and a decrease in reliability.
[0005]
The present invention solves the above-mentioned problem, and has a desirable characteristic that a conductive polymer layer having a uniform thickness and a desired thickness on the capacitor element surface is formed with excellent mechanical strength and excellent productivity. Another object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor.
[0006]
[Means for Solving the Problems]
The present invention has been completed as a result of studies to solve the above-mentioned problems of the prior art. That is, in a method for producing a solid electrolytic capacitor using a conductive polymer layer as a solid electrolyte, a conductive polymer layer made of polythiophene or a derivative thereof formed on a capacitor element surface made of a tantalum sintered body is formed on the capacitor element surface. The composite conductive polymer layer formed by taking in the adhering pulp and papermaking adhesive makes it possible to form a solid electrolyte with excellent mechanical strength. did.
[0007]
The present invention relates to a capacitor element in which a dielectric oxide film is formed on the surface of an element body made of a valve metal serving as an anode, and a solid electrolytic capacitor comprising a conductive polymer layer formed on the surface of the dielectric oxide film. In the manufacturing method, the conductive polymer layer formed on the capacitor element surface is made of polythiophene or a derivative thereof, and is composed of a composite conductive polymer layer formed by taking in pulp and papermaking adhesive attached to the capacitor element surface. It is characterized by that.
[0008]
Further, the papermaking adhesive is characterized by comprising a natural paste such as grated cocoon or glue paste, or a synthetic paste such as polyethylene oxide or polyacrylamide.
[0010]
As a means of composing a composite conductive polymer layer of such a conductive polymer layer and pulp and papermaking adhesive, a capacitor element made of a tantalum sintered body is immersed in an aqueous solution in which pulp is suspended and dried. In the manufacturing method of a solid electrolytic capacitor in which pulp is attached to the surface of the capacitor element and then immersed in a monomer solution and then immersed in an oxidizer solution and chemically oxidatively polymerized, when making an aqueous solution in which pulp is suspended, By adding a viscosity agent and dispersing the pulp.
[0011]
Here, the solution in which the pulp is suspended may be stirred and the pulp may flow gently.
[0012]
Furthermore, in the above-mentioned means, a dense and strong composite conductive polymer layer can be obtained by forming a conductive polymer layer on the capacitor element in advance.
[0013]
By constructing a composite of conductive polymer and pulp and papermaking adhesive, increase the thickness with pulp and papermaking adhesive, reduce the polymerization time and frequency, increase productivity, and capacitor element A uniform and thick conductive polymer layer can be formed on the surface, the mechanical strength is improved, the stress at the time of resin exterior can be withstood, and a good solid electrolytic capacitor without increasing leakage current or reducing reliability can be obtained.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a capacitor element in which a dielectric oxide film is formed on the surface of a tantalum sintered body serving as an anode, and a solid electrolytic capacitor comprising a conductive polymer layer formed on the surface of the dielectric oxide film. In this manufacturing method, the conductive polymer layer formed on the surface of the capacitor element is composed of polythiophene or a derivative thereof, and is composed of a composite conductive polymer layer formed by taking in pulp and papermaking adhesive attached to the capacitor element surface. It is characterized by that.
[0015]
Note that the capacitor element configuration is not limited to a special one as a means for forming a fine powder sintered body or a dielectric oxide film, and a known means is used.
[0016]
The composite conductive polymer layer having a large film thickness due to the presence of pulp and papermaking adhesive attached to the capacitor element surface can reduce the number of polymerizations and the polymerization time, thereby contributing to productivity improvement. In addition, since the composite conductive polymer layer has improved mechanical strength, it can withstand the stress when the resin is packaged, and a good solid electrolytic capacitor without increasing leakage current or reducing reliability can be obtained.
[0017]
The present invention is characterized in that the papermaking adhesive is composed of natural glue such as grated cocoon and glue paste, or synthetic glue such as polyethylene oxide and polyacrylamide, and is used at a concentration of 0.01 to 0.1%. Thus, a desired pulp layer can be formed uniformly and in a small number of times, which greatly contributes to improvement in productivity and various characteristics.
[0018]
Moreover, the pulp which consists of the pulp adhering to the surface of a capacitor | condenser element, especially the fully beaten pulp develops a fibril, and it becomes entangled with the unevenness | corrugation of a capacitor | condenser element, and formation of a pulp layer becomes easy. In addition, in order to make it easy to secure the thickness of the attached pulp, it is possible to mix a thick pulp with insufficient beating and long fibers with a sufficiently advanced beating, or to select the suspension concentration of the pulp as appropriate. it can.
[0019]
In the invention according to claim 1, after immersing a capacitor element made of a tantalum sintered body in an aqueous solution in which pulp is suspended, the capacitor element is dried to adhere the pulp to the surface of the capacitor element, and then immersed in the monomer solution. In a method for producing a solid electrolytic capacitor that is immersed in an oxidant solution and chemically oxidatively polymerized, an aqueous solution in which pulp is suspended is a method for producing a solid electrolytic capacitor characterized in that pulp is dispersed by adding a papermaking adhesive. By adding a papermaking adhesive to an aqueous solution in which pulp is suspended, formation of a desired pulp layer is facilitated, which greatly contributes to improvement of productivity and various properties.
[0020]
In the invention according to claim 2, a conductive polymer layer is formed in advance on the capacitor element, and then the capacitor element is immersed in an aqueous solution in which pulp is suspended and then dried to adhere the pulp to the surface of the capacitor element. Next, in the method for producing a solid electrolytic capacitor, which is immersed in a monomer solution and then immersed in an oxidizer solution and chemically oxidatively polymerized, the aqueous solution in which the pulp is suspended is characterized in that the pulp is dispersed by adding a papermaking adhesive. The method for producing a solid electrolytic capacitor as described above facilitates the formation of a conductive polymer layer inside the capacitor element and greatly contributes to improving productivity and various characteristics.
[0021]
In the present invention, as described above, after forming a composite conductive polymer layer as an electrolyte, it is dried as necessary, and a graphite layer and a silver paint layer are formed thereon by a known means, and then drawn out. An electrode is provided and a resin sheath is applied to obtain a finished product.
[0022]
【Example】
Hereinafter, the basic structure of the solid electrolytic capacitor of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a capacitor element formed by forming an anodized film on the surface of a sintered body made of tantalum fine powder as a valve action metal serving as an anode, and 2 is for pulp and paper making attached to the surface of this capacitor element 1 A composite conductive polymer layer formed by incorporating the adhesive 3, 4 is a carbon layer formed on the composite conductive polymer layer 2, and 5 is a silver paint serving as a cathode formed on the carbon layer 4. 6 is an anode wire embedded in the sintered body, 7 is an anode lead terminal connected to the anode wire 6, 8 is a cathode lead terminal connected to the silver paint layer 5, and 9 is a resin exterior. Is a layer.
[0023]
Next, specific examples will be described in detail in comparison with comparative examples. That is, as a result of measuring the capacity | capacitance, leakage current, and ESR characteristic of Examples 1-4 shown below and Comparative Examples 1 and 2 which concern on a prior art, it was as showing in Table 1.
[0024]
Example 1 A tantalum sintered body having a size of 3.9 × 3.3 × 1.6 mm 3 was used as the anode, and a tantalum wire was used as the anode wire. Anodized in an aqueous solution at 90 ° C. and 40 V for 180 minutes, washed with running deionized water and dried to obtain a capacitor element. Note that the capacitance in the chemical conversion liquid was measured as 100 μF.
[0025]
Next, this capacitor element is immersed for 7 minutes in a monomer solution obtained by mixing 50 g of butyl alcohol and 50 g of 3,4-ethylenedioxythiophene, and then para-toluenesulfonic acid second as an oxidizing agent containing transition metal ions. It is immersed for 15 minutes in an oxidant solution obtained by dissolving 40 g of iron in 60 g of butanol, subjected to chemical oxidative polymerization, forms a conductive polymer layer on the anodized film constituting the capacitor element, and is washed with butanol. After 5 minutes, it was dried at 105 ° C. for 5 minutes. The number of polymerizations until dipping and drying in the monomer solution was repeated 10 times until the conductive polymer layer had a desired thickness.
[0026]
Next, the capacitor element in which the conductive polymer layer is formed in this way is immersed in a suspension of 2 wt% pulp and 0.05 wt% synthetic paste to attach the pulp to the surface of the capacitor element. In this case, the suspension is stirred, and the pulp can be effectively adhered to the surface of the capacitor element by being immersed in the flowing pulp. Especially, the capacitor element edge portion where mechanical strength is required. Can adhere more effectively. Thus, the capacitor element to which the pulp was adhered in this manner was dried at 105 ° C. for 5 minutes. In addition, until the pulp layer became desired thickness, the process from immersion to suspension to drying was repeated twice.
[0027]
Next, the capacitor element with the pulp attached to the surface is again immersed in the monomer solution for 7 minutes, immersed in the oxidant solution for 15 minutes to perform chemical oxidative polymerization, washed with butanol for 5 minutes, and then subjected to 105 ° C. The process of drying for 5 minutes was repeated 5 times to form a composite conductive polymer layer in which pulp having a desired thickness was taken in on the capacitor element surface. Then, a carbon layer is formed on the composite conductive polymer layer, a silver paint layer serving as a cathode is formed on the carbon layer, and a cathode lead terminal is drawn from the anode body on the silver paint layer. An anode lead terminal was attached to each of the anode wires, a resin sheath was applied by transfer molding, and the cathode lead terminal and the anode lead terminal were bent at predetermined positions to complete a chip-shaped solid electrolytic capacitor.
[0028]
Example 2 A capacitor element having a conductive polymer layer formed therein by the same means as in Example 1 is made to adhere pulp to the capacitor element by the same means as in Example 1. In addition, the process from the immersion to a suspension to drying was repeated 8 times until the pulp became a desired thickness. Next, a composite conductive polymer layer is formed on a capacitor element having a pulp adhered to the surface to obtain a finished product. The means is the same as in Example 1.
[0029]
(Embodiment 3) A capacitor element formed by the same means as in Embodiment 1 is made to adhere pulp to the surface of the capacitor element by the same means as in Embodiment 1. In addition, until the pulp layer became desired thickness, the process from immersion to suspension to drying was repeated twice.
[0030]
Next, the capacitor element with the pulp attached to the surface is immersed in the monomer solution for 7 minutes and immersed in the oxidant solution for 15 minutes by the same means as in Example 1 to perform chemical oxidative polymerization, and washed with running water with butanol. After 5 minutes, the process of drying at 105 ° C. for 5 minutes was repeated 15 times to form a composite conductive polymer layer in which pulp having a desired thickness was taken in on the capacitor element surface. Thus, a chip-shaped solid electrolytic capacitor was completed by the same means as in Example 1.
[0031]
(Embodiment 4) A capacitor element formed by the same means as in Embodiment 3 is made to adhere pulp to the surface of the capacitor element by the same means as in Embodiment 1. In addition, the process from the immersion to a suspension to drying was repeated 8 times until the pulp layer became desired thickness.
[0032]
Next, a composite conductive polymer layer was formed by the same means as in Example 3 on the capacitor element having the pulp adhered to the surface. The means from the formation of the composite conductive polymer layer to the completion of the finished product is the same as in Example 3.
[0033]
(Comparative example 1) Except for the step of attaching pulp to the surface of the capacitor element, the finished product is obtained through the same steps as in Example 1, but since the pulp is not attached to the surface of the capacitor element, the surface of the capacitor element This conductive polymer layer structure is not compounded with pulp and is merely a conductive polymer layer, and the number of polymerizations in this case is 61 times.
[0034]
(Comparative Example 2) This was completed through the same steps as in Comparative Example 1 except that the number of polymerizations was 15 times.
[0035]
[Table 1]

[0036]
As is clear from Table 1, all of Examples 1, 2, 3, and 4 can provide a solid electrolytic capacitor that is excellent in leakage current and ESR characteristics and highly reliable. No. 2 shows no problem in ESR characteristics, but even if the number of times of polymerization is 61 times as in Comparative Example 1, the leakage current characteristics are not good and it is not practically preferable. In this embodiment, the difference is that the conductive polymer layer formed on the surface of the capacitor element is composed of a composite conductive polymer layer incorporating pulp and papermaking adhesive to increase the layer thickness. This is based on the result that the mechanical strength of the polymer layer is increased and the conductive polymer layer is not damaged by the stress in the exterior resin process. Among Comparative Examples, Comparative Example 1 with the best leakage current characteristics also requires 61 times of polymerization, which is not preferable from the viewpoint of productivity. However, it can be seen that the leakage current characteristics are excellent, which can greatly contribute to the improvement of productivity.
[0037]
【The invention's effect】
As described above, according to the present invention, in a method for manufacturing a solid electrolytic capacitor in which a conductive polymer layer is formed on the surface of an oxide film constituting a capacitor element made of a valve metal, the conductive polymer layer is Capable of improving productivity by reducing the number of polymerizations by increasing the thickness of the conductive polymer layer by using a composite conductive polymer layer formed by incorporating pulp and papermaking adhesive attached to the capacitor element surface. A solid electrolytic capacitor having good leakage current characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the basic structure of a solid electrolytic capacitor of the present invention.
[Explanation of symbols]
1 Capacitor element 2 Composite conductive polymer layer 3 Pulp 4 Carbon layer 5 Silver paint layer 6 Anode wire 7 Anode lead terminal 8 Cathode lead terminal 9 Exterior resin layer

Claims

Solid electrolytic capacitor in which a conductive polymer layer made of polythiophene or a derivative thereof is formed on the surface of the dielectric oxide film of a capacitor element formed by forming a dielectric oxide film on the surface of a tantalum sintered body serving as an anode In the manufacturing method, after immersing a capacitor element made of a tantalum sintered body in an aqueous solution in which pulp is suspended, the capacitor element is dried to adhere the pulp to the surface of the capacitor element, and then immersed in a monomer solution, and then an oxidant solution. A method for producing a solid electrolytic capacitor, wherein an aqueous solution in which pulp is suspended is added with a papermaking adhesive to disperse the pulp.

Solid electrolytic capacitor in which a conductive polymer layer made of polythiophene or a derivative thereof is formed on the surface of the dielectric oxide film of a capacitor element formed by forming a dielectric oxide film on the surface of a tantalum sintered body serving as an anode In this manufacturing method, a conductive polymer layer is formed in advance on the capacitor element, and then the capacitor element is immersed in an aqueous solution in which pulp is suspended and then dried to adhere the pulp to the surface of the capacitor element. In the method for producing a solid electrolytic capacitor in which the aqueous solution in which the pulp is suspended is immersed in the monomer solution and then immersed in the oxidizer solution and chemically oxidatively polymerized, the pulp is dispersed by adding a papermaking adhesive. A method for producing a solid electrolytic capacitor.

The method for producing a solid electrolytic capacitor according to claim 1, wherein the capacitor element is immersed by flowing a pulp in an aqueous solution in which the pulp is suspended.

4. The method for producing a solid electrolytic capacitor according to claim 1, wherein the concentration of the papermaking adhesive in the aqueous pulp and papermaking adhesive is 0.01 to 0.1%.