JP2002033247A - Solid electrolytic capacitor and method of manufacturing the same - Google Patents
Solid electrolytic capacitor and method of manufacturing the sameInfo
- Publication number
- JP2002033247A JP2002033247A JP2000215595A JP2000215595A JP2002033247A JP 2002033247 A JP2002033247 A JP 2002033247A JP 2000215595 A JP2000215595 A JP 2000215595A JP 2000215595 A JP2000215595 A JP 2000215595A JP 2002033247 A JP2002033247 A JP 2002033247A
- Authority
- JP
- Japan
- Prior art keywords
- silver
- layer
- manganese dioxide
- silver particles
- dioxide layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、固体電解コンデン
サ及びその製造方法に関し、特に、陽極体に弁作用金属
の粉末から得た焼結体を用い、固体電解質に二酸化マン
ガンを用いる固体電解コンデンサとその製造方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor and a method of manufacturing the same, and more particularly to a solid electrolytic capacitor using a sintered body obtained from a valve metal powder as an anode body and using manganese dioxide as a solid electrolyte. It relates to the manufacturing method.
【０００２】[0002]
【従来の技術】この種の固体電解コンデンサについて、
タンタル固体電解コンデンサを例にして説明する。従来
のタンタル固体電解コンデンサの素子の一例（従来例
１）の断面を模式的に示す図２を参照して、この図に示
すコンデンサ素子は、タンタル粉末を角柱或いは円柱に
プレス成形し焼結して得た微多孔質の焼結ペレット２
と、その焼結ペレットの内表面、外表面に形成された酸
化タンタル（Ｔａ2 Ｏ5 ）の皮膜３と、酸化タンタル皮
膜上に形成された二酸化マンガン層４と、二酸化マンガ
ン層上のカーボン層５及びその上の銀層６とからなって
いる。焼結ペレット２は陽極体であり、酸化タンタル皮
膜３は誘電体であり、二酸化マンガン層４は固体電解質
である。この二酸化マンガン層４と、その上のカーボン
層５と、更にその上の銀層６の三つの層で陰極側の引出
し層をなしている。焼結ペレット２の長手方向の一端面
に紙面上向きに飛び出すように植立されているタンタル
ワイヤ１は、陽極側の引出し線（陽極リード）として機
能するものである。2. Description of the Related Art A solid electrolytic capacitor of this type includes:
A description will be given taking a tantalum solid electrolytic capacitor as an example. Referring to FIG. 2, which schematically shows a cross section of an example of a conventional tantalum solid electrolytic capacitor element (conventional example 1), the capacitor element shown in this figure is formed by pressing and molding tantalum powder into a prism or a cylinder. Microporous sintered pellet 2
And a film 3 of tantalum oxide (Ta 2 O 5 ) formed on the inner and outer surfaces of the sintered pellet, a manganese dioxide layer 4 formed on the tantalum oxide film, and a carbon layer on the manganese dioxide layer 5 and a silver layer 6 thereon. The sintered pellet 2 is an anode, the tantalum oxide film 3 is a dielectric, and the manganese dioxide layer 4 is a solid electrolyte. The three layers of the manganese dioxide layer 4, the carbon layer 5 thereon, and the silver layer 6 thereon further form a cathode-side extraction layer. The tantalum wire 1 implanted on one end surface of the sintered pellet 2 in the longitudinal direction so as to protrude upward on the paper surface functions as a lead wire (anode lead) on the anode side.
【０００３】上述のコンデンサ素子において、二酸化マ
ンガン層４、カーボン層５及び銀層６の三つの層は陰極
側の引出し層をなしているのであるが、この陰極側引出
し層の構造に着目すると、二酸化マンガン層４と銀層６
との間にカーボン層５を介在させている点に、従来例１
のコンデンサの構造上の特徴がある。このようにカーボ
ン層を介在させるのは、次の理由による。すなわち、固
体電解質の層である二酸化マンガン層４の表面は微細に
粗面化されていて、通常、数ミクロン程度のピッチの凹
凸をもっている。一方、銀層６を構成する銀粒子の粒径
は、その二酸化マンガン層４の表面の凹凸のピッチと同
程度か或いはそれより大きい。従って、上記の微細に粗
面化された二酸化マンガン層４上に直接銀層６を形成し
ようとすると、銀粒子は固体電解質４の内部にまで入り
込んで行かない。その結果、二酸化マンガン層４と銀層
６との間の接触面積が小さくなり接触抵抗が高くなっ
て、誘電体（この場合は、酸化タンタル皮膜３）に直列
に加わる抵抗が大きくなってしまう。そこで、銀粒子よ
り微粒の導電物質である微粉カーボン粒子を先に二酸化
マンガン層４に付着させ、二酸化マンガン層の粗面を埋
めておいてから銀層６を形成することで、上記陰極側の
直列抵抗を下げているのである。In the above-mentioned capacitor element, the three layers of the manganese dioxide layer 4, the carbon layer 5, and the silver layer 6 form a cathode-side extraction layer. Focusing on the structure of the cathode-side extraction layer, Manganese dioxide layer 4 and silver layer 6
In that the carbon layer 5 is interposed between
There is a structural feature of the capacitor. The reason for interposing the carbon layer in this manner is as follows. That is, the surface of the manganese dioxide layer 4, which is a layer of the solid electrolyte, is finely roughened and usually has irregularities with a pitch of about several microns. On the other hand, the particle size of the silver particles constituting the silver layer 6 is equal to or larger than the pitch of the irregularities on the surface of the manganese dioxide layer 4. Therefore, if the silver layer 6 is to be formed directly on the finely roughened manganese dioxide layer 4, the silver particles do not penetrate into the solid electrolyte 4. As a result, the contact area between the manganese dioxide layer 4 and the silver layer 6 is reduced, the contact resistance is increased, and the resistance applied in series to the dielectric (in this case, the tantalum oxide film 3) is increased. Therefore, fine carbon particles, which are finer conductive materials than silver particles, are first adhered to the manganese dioxide layer 4 to fill the rough surface of the manganese dioxide layer, and then the silver layer 6 is formed. The series resistance has been lowered.
【０００４】しかしながら、固体電解コンデンサの低直
列抵抗化に対する要望は強く、更なる改善策が望まれて
いる。そのような改善策の一つ（従来例２）が、特開平
５−１４４６８４号公報に開示されている。上記公報記
載の固体電解コンデンサの製造方法においては、カーボ
ン層を省いて銀層を直接二酸化マンガン層上に形成す
る。その際、それまでより粒径の小さい銀粉末を用い
て、微粉銀粒子が二酸化マンガン層の微細な凹凸内に進
入するようにしている。これにより、カーボン層を省き
ながらも微粉銀粒子と二酸化マンガン層との接触面積を
確保して、カーボン層の抵抗の分だけ、陰極側の直列抵
抗を下げている。[0004] However, there is a strong demand for lowering the series resistance of the solid electrolytic capacitor, and further improvement measures are desired. One such improvement (conventional example 2) is disclosed in Japanese Patent Application Laid-Open No. 5-144684. In the method of manufacturing a solid electrolytic capacitor described in the above publication, the silver layer is formed directly on the manganese dioxide layer without the carbon layer. At that time, silver powder having a smaller particle size is used so that the fine silver particles enter the fine irregularities of the manganese dioxide layer. Thereby, the contact area between the fine silver particles and the manganese dioxide layer is secured while the carbon layer is omitted, and the series resistance on the cathode side is reduced by the resistance of the carbon layer.
【０００５】すなわち、上記公報の実施例では、それま
で平均粒径が２．０μｍの銀粉末を用いていたところ、
これを平均粒径０．７μｍの微粉銀粒子に変える。そし
て、二酸化マンガン層の形成迄が済んだ焼結ペレット
を、上記の微粉銀粒子を３５ｗｔ％含む縣濁液中に浸漬
させ、引き上げ、温度：１５０℃、時間：１時間の条件
で焼き付けることで、二酸化マンガン層上に直接銀層を
形成している。この銀層の形成に用いる微粉銀粒子の縣
濁液は、上記平均粒径０．７μｍの微粉銀粒子を例えば
エポキシ樹脂と混練し、これを酢酸ブチルなどの溶媒に
分散させることによって得ている。That is, in the examples of the above publication, silver powder having an average particle size of 2.0 μm was used until then.
This is changed to fine silver particles having an average particle size of 0.7 μm. Then, the sintered pellets in which the formation of the manganese dioxide layer has been completed are immersed in a suspension containing 35% by weight of the above fine silver particles, pulled up, and baked under the conditions of temperature: 150 ° C., time: 1 hour. The silver layer is formed directly on the manganese dioxide layer. The suspension of the fine silver particles used for forming the silver layer is obtained by kneading the fine silver particles having an average particle diameter of 0.7 μm with, for example, an epoxy resin and dispersing the kneaded particles in a solvent such as butyl acetate. .
【０００６】[0006]
【発明が解決しようとする課題】上述した従来例２の固
体電解コンデンサの製造方法によれば、銀層を構成する
銀粒子の粒径をそれまでのものより小さくし、そのよう
な微粒化した銀粉末と樹脂とを混練したものを予め溶媒
に分散させ、これに焼結ペレットを浸漬させることで、
微粉銀粒子が二酸化マンガン層表面の凹凸内に進入でき
るようにすることができる。これにより、それまで必要
であったカーボン層を省き、銀層を二酸化マンガン層上
に直接形成しながらも接触面積を確保して、カーボン層
の分だけコンデンサの陰極側の直列抵抗を小さくするこ
とができる。According to the method for manufacturing the solid electrolytic capacitor of the above-mentioned prior art example 2, the silver particles constituting the silver layer are made smaller than those of the prior art, and such silver particles are made finer. By kneading a mixture of silver powder and resin in a solvent in advance, and immersing the sintered pellets in this,
Fine silver particles can be allowed to enter the irregularities on the surface of the manganese dioxide layer. This eliminates the carbon layer, which was necessary until then, and secures the contact area while forming the silver layer directly on the manganese dioxide layer, thereby reducing the series resistance on the cathode side of the capacitor by the carbon layer. Can be.
【０００７】しかしながら、二酸化マンガン層上に直接
付着させる銀粒子は粒径が小さいほど二酸化マンガン層
の凹凸内に進入し易いと考えられるにも拘らず、従来例
２のような縣濁液の形成方法、すなわち微粉銀粒子と例
えばエポキシのような樹脂とを混練し、これを溶媒に分
散させる方法で均一に分散させ得る微粉銀粒子の最小粒
径は、０．１μｍ程度が限度と推測される。また、従来
例２の方法で得られた銀層は、エポキシ樹脂中に銀粒子
が分散した状態になっている。この微粉銀粒子と混練す
る樹脂は、微粉銀粒子の分散性をよくするためと形成さ
れた銀層における耐湿性のような耐環境性を高めるため
のものと考えれられるが、樹脂自体は電気絶縁性である
ので、コンデンサにおける低直列抵抗化の観点からは、
銀層は銀粒子以外の樹脂を含まない方がより効果的であ
ろうと考えられる。[0007] However, the silver particles deposited directly on the manganese dioxide layer are thought to be easier to enter into the irregularities of the manganese dioxide layer as the particle size is smaller. The minimum particle size of the fine silver particles that can be uniformly dispersed by the method, that is, kneading the fine silver particles and a resin such as epoxy, for example, and dispersing the same in a solvent is estimated to be about 0.1 μm as a limit. . Further, the silver layer obtained by the method of Conventional Example 2 is in a state where silver particles are dispersed in the epoxy resin. The resin kneaded with the fine silver particles is considered to improve the dispersibility of the fine silver particles and to enhance environmental resistance such as moisture resistance in the formed silver layer, but the resin itself is electrically insulating. Therefore, from the viewpoint of reducing the series resistance of the capacitor,
It is thought that it would be more effective for the silver layer not to contain a resin other than silver particles.
【０００８】従って本発明は、陽極体に弁作用金属の粉
末から得た焼結体を用い、固体電解質に二酸化マンガン
を用いる固体電解コンデンサにおいて、粒径が０．１μ
ｍより小なる銀粒子を用いて、銀粒子のみからなる銀層
を直接二酸化マンガン層上に形成できるようにすること
を目的とするものである。Accordingly, the present invention provides a solid electrolytic capacitor in which a sintered body obtained from a valve metal powder is used for an anode body and manganese dioxide is used as a solid electrolyte.
It is an object of the present invention to form a silver layer composed of only silver particles directly on a manganese dioxide layer using silver particles smaller than m.
【０００９】[0009]
【課題を解決するための手段】本発明の固体電解コンデ
ンサの製造方法は、弁作用金属の粉末を成形し焼結して
焼結体を得る工程と、前記焼結体の表面に誘電体皮膜を
形成する工程と、前記誘電体皮膜上に二酸化マンガン層
を形成する工程と、前記二酸化マンガン層上に銀粒子の
みからなる銀層を直接形成する工程とを含んでいる。A method for manufacturing a solid electrolytic capacitor according to the present invention comprises the steps of molding and sintering a valve metal powder to obtain a sintered body, and forming a dielectric film on the surface of the sintered body. Forming a manganese dioxide layer on the dielectric film, and directly forming a silver layer composed of only silver particles on the manganese dioxide layer.
【００１０】そして、上記の銀層を形成するに際し、前
記二酸化マンガン層形成済みの焼結体を、溶媒と予め分
散剤で被覆した銀粒子とのみからなる銀粒子の縣濁液に
浸漬させ、引き上げ、所定の温度で焼き付けることによ
り前記銀粒子のみからなる銀層を直接二酸化マンガン層
上に形成することを特徴とし、前記分散剤に飽和脂肪酸
を用いることを特徴とする。分散剤としての飽和脂肪酸
には、ミリスチン酸、ステアリン酸及びラウリン酸のい
ずれか一つを用いることができる。In forming the silver layer, the sintered body on which the manganese dioxide layer has been formed is immersed in a suspension of silver particles consisting only of a solvent and silver particles previously coated with a dispersant, The silver layer composed of only the silver particles is directly formed on the manganese dioxide layer by pulling and baking at a predetermined temperature, and a saturated fatty acid is used as the dispersant. Any one of myristic acid, stearic acid and lauric acid can be used as a saturated fatty acid as a dispersant.
【００１１】本発明者は、微粉銀粒子の表面を飽和脂肪
酸の一つであるミリスチン酸で予め被覆すると、粒径
０．１μｍ未満に微粒化した場合でも銀粒子が凝集する
ことなく、銀粉末が単分散金属微粒子の状態で溶媒に均
一に分散すること、そのような微粒銀粉末と溶媒とのみ
からなる縣濁液にコンデンサの焼結ペレットを浸漬させ
ることで、二酸化マンガン層上に飽和脂肪酸で被覆され
た粒径３ｎｍ以上、１００ｎｍ未満の微粉銀粒子からな
る銀層を被着させることができること及び、その後２０
０℃程度の温度で焼き付けることで飽和脂肪酸を分解、
揮散させて、微粉銀粒子のみからなる銀層を形成できる
ことを見出した。微粉銀粒子は通常、銀の無機塩を熱分
解して製造するが、その際に飽和脂肪酸（Ｒ−ＣＯＯ
Ｈ。Ｒは、アルキル基）を添加しておくと、金属表面に
飽和脂肪酸の−ＯＨ基が反応して銀粒子表面に飽和脂肪
酸が付着したような状態になり、銀粒子どうしの凝集を
妨げるものと考えられる。The present inventors have proposed that when the surface of fine silver particles is coated in advance with myristic acid, which is one of saturated fatty acids, the silver particles will not aggregate even if the particle size is reduced to less than 0.1 μm, and the silver powder will not be agglomerated. Is uniformly dispersed in a solvent in the state of monodispersed metal fine particles, and by immersing the sintered pellet of the capacitor in a suspension consisting only of such fine silver powder and solvent, the saturated fatty acid is placed on the manganese dioxide layer. A silver layer composed of finely divided silver particles having a particle size of 3 nm or more and less than 100 nm coated with
Decompose saturated fatty acids by baking at a temperature of about 0 ° C,
It has been found that a silver layer consisting of only fine silver particles can be formed by volatilization. Finely divided silver particles are usually produced by thermally decomposing an inorganic salt of silver, in which case saturated fatty acids (R-COO
H. R is an alkyl group), the -OH group of the saturated fatty acid reacts on the metal surface to form a state in which the saturated fatty acid adheres to the silver particle surface, which prevents aggregation of silver particles. Conceivable.
【００１２】[0012]
【発明の実施の形態】次に、本発明の実施の形態につい
て説明する。本発明の一実施の形態に係るタンタル固体
電解コンデンサの断面図を模式的に示す図１を参照し
て、本実施の形態においては、タンタル粉末からの焼結
ペレット２の作製、その焼結ペレットの表面への酸化タ
ンタル皮膜３及び二酸化マンガン層４の形成までを、従
来公知の方法で順次行った。すなわち、先ず、タンタル
の粉末にバインダを混合したものを、直方体にプレス成
形する。このプレスでの成形の際に、別途用意しておい
たタンタルワイヤ１を、直方体の長手方向の一端面に植
立する。このタンタルワイヤ１は、完成したコンデンサ
素子で陽極リードとなるべきものである。次に、上記の
プレス成形体を真空中で１４００℃に加熱し、焼結し
て、微多孔質の焼結ペレット２を得る。その後、この焼
結ペレットをリン酸水溶液からなる化成溶液中に浸漬さ
せ、焼結ペレット２にプラス、化成溶液にマイナスの電
位を与えて陽極化成して、焼結ペレットの外表面及び内
部の微細孔の表面に誘電体層としての酸化タンタル皮膜
３を形成する。更に、上記酸化タンタル皮膜３上に、固
体電解質層としての二酸化マンガン層４を形成する。二
酸化マンガン層４は、焼結ペレット２を硝酸マンガン水
溶液中に浸漬させ、焼結ペレットに硝酸マンガン水溶液
を含浸させて引き上げ、熱分解させる操作を繰り返して
行うことで形成する。繰返しの途中で、熱分解による酸
化タンタル皮膜の損傷を修復する目的で、再化成を行
う。Next, an embodiment of the present invention will be described. Referring to FIG. 1 schematically showing a cross-sectional view of a tantalum solid electrolytic capacitor according to one embodiment of the present invention, in this embodiment, production of sintered pellet 2 from tantalum powder, The steps up to the formation of the tantalum oxide film 3 and the manganese dioxide layer 4 on the surface were sequentially performed by a conventionally known method. That is, first, a mixture of tantalum powder and a binder is press-formed into a rectangular parallelepiped. At the time of molding by this press, a separately prepared tantalum wire 1 is implanted on one end surface in the longitudinal direction of the rectangular parallelepiped. This tantalum wire 1 is to be an anode lead in the completed capacitor element. Next, the above-mentioned press-formed body is heated to 1400 ° C. in a vacuum and sintered to obtain a microporous sintered pellet 2. Thereafter, the sintered pellets are immersed in a chemical conversion solution composed of a phosphoric acid aqueous solution, and anodized by applying a positive potential to the sintered pellets 2 and a negative potential to the chemical conversion solution to form fine particles on the outer surface and inside of the sintered pellets. A tantalum oxide film 3 as a dielectric layer is formed on the surface of the hole. Further, a manganese dioxide layer 4 as a solid electrolyte layer is formed on the tantalum oxide film 3. The manganese dioxide layer 4 is formed by immersing the sintered pellets 2 in an aqueous solution of manganese nitrate, impregnating the sintered pellets with the aqueous solution of manganese nitrate, pulling up, and thermally decomposing the pellets repeatedly. In the middle of the repetition, re-chemical conversion is performed in order to repair the damage of the tantalum oxide film due to thermal decomposition.
【００１３】上述のようにして、従来公知の方法で二酸
化マンガン層４までを形成した後、その二酸化マンガン
層４上に、本実施の形態の方法により、粒径が３ｎｍ以
上、１００ｎｍ未満の微粉銀粒子のみからなる銀層６Ａ
を直接形成した。すなわち、粒径が上記範囲内で表面が
予めミリスチン酸で被覆されている微粉銀粒子を溶媒で
ある酢酸ブチルに分散させて、微粉銀粒子の縣濁液を準
備しておき、二酸化マンガン層４の形成までを済ませた
焼結ペレットを上記微粉銀粒子の縣濁液に浸漬させ、引
き上げ、温度：２００℃、時間：６０分の条件で焼き付
けて、ミリスチン酸を分解、揮散させた。縣濁液中の微
粉銀粒子の濃度は、５ｗｔ％である。ミリスチン酸で被
覆された粒径３ｎｍ以上、１００ｎｍ未満の微粉銀粒子
には、大研化学工業（株）製の銀粉末（商品名：ＤＴＡ
−２Ａ。平均粒径：５ｎｍ）を用いた。After forming up to the manganese dioxide layer 4 by a conventionally known method as described above, the fine powder having a particle size of 3 nm or more and less than 100 nm is formed on the manganese dioxide layer 4 by the method of the present embodiment. Silver layer 6A consisting only of silver particles
Was formed directly. That is, fine silver particles whose particle diameter is within the above range and whose surface is previously coated with myristic acid are dispersed in butyl acetate as a solvent to prepare a suspension of fine silver particles, and the manganese dioxide layer 4 is prepared. The sintered pellets having been subjected to the formation of the particles were immersed in the suspension of the fine silver particles, pulled up, and baked at a temperature of 200 ° C. for a time of 60 minutes to decompose and volatilize myristic acid. The concentration of fine silver particles in the suspension is 5 wt%. Fine powder silver particles having a particle size of 3 nm or more and less than 100 nm coated with myristic acid include silver powder (trade name: DTA) manufactured by Daiken Chemical Industry Co., Ltd.
-2A. Average particle size: 5 nm).
【００１４】以後、従来公知の方法により、陽極リード
１に図示しない外部陽極端子を溶接し、銀層６Ａには同
じく図示しない外部陰極端子を導電性接着剤で取り付
け、エポキシ樹脂を用いたトランスファーモールド工法
で外装を施した後、陽、陰両外部端子の外装樹脂から出
た部分を外装樹脂に沿って折り曲げ、整形して、本実施
の形態に係るチップ型タンタル固体電解コンデンサを完
成させた。Thereafter, an external anode terminal (not shown) is welded to the anode lead 1 by a conventionally known method, an external cathode terminal (not shown) is attached to the silver layer 6A with a conductive adhesive, and transfer molding using an epoxy resin is performed. After the exterior was provided by the construction method, the portions of the positive and negative external terminals protruding from the exterior resin were bent and shaped along the exterior resin to complete the chip-type tantalum solid electrolytic capacitor according to the present embodiment.
【００１５】次に、本発明者は、以下に述べるようにし
て比較例のチップ型タンタルコンデンサを作製した。す
なわち、実施の形態と同一の製造工程、条件で二酸化マ
ンガン層４形成済みの焼結ペレットを作製した後、従来
公知の方法で、二酸化マンガン層上にカーボン層５（図
２参照）を形成し、更にそのカーボン層５上に銀層６
（同）を形成して、図２に示す従来例１の構造のコンデ
ンサ素子を得た。Next, the present inventor manufactured a chip type tantalum capacitor of a comparative example as described below. That is, after producing a sintered pellet having the manganese dioxide layer 4 formed thereon under the same manufacturing process and conditions as those of the embodiment, a carbon layer 5 (see FIG. 2) is formed on the manganese dioxide layer by a conventionally known method. And a silver layer 6 on the carbon layer 5.
Was formed to obtain a capacitor element having the structure of Conventional Example 1 shown in FIG.
【００１６】カーボン層５は、粒径１〜５μｍの粉末カ
ーボン粒子を純水に分散させた縣濁液中に二酸化マンガ
ン層形成済みの焼結ペレットを浸漬させ、引き上げ、温
度：１５０℃、時間：３０分の条件で焼き付けることに
よって形成した。銀層６は、粒径５〜２０μｍの銀粉末
とエポキシ樹脂とを混練し、これを酢酸ブチルで稀釈し
たものの中にカーボン層４形成済みの焼結ペレットを浸
漬させ、引き上げ、温度：２００℃、時間：６０分の条
件で焼き付けることによって形成した。The carbon layer 5 is prepared by immersing a sintered pellet having a manganese dioxide layer formed therein in a suspension in which powdered carbon particles having a particle size of 1 to 5 μm are dispersed in pure water, and pulling up the same. : Formed by baking under conditions of 30 minutes. The silver layer 6 is obtained by kneading a silver powder having a particle size of 5 to 20 μm and an epoxy resin, diluting the mixture with butyl acetate, immersing the sintered pellets on which the carbon layer 4 has been formed, and pulling up the same. , Time: formed by baking under conditions of 60 minutes.
【００１７】上記銀層６の形成後、実施の形態と同一の
製造工程、条件で陽、陰両外部端子を取り付け、外装を
施し、両外部端子の整形を行って比較例のチップ型タン
タル固体電解コンデンサを完成させた。After the formation of the silver layer 6, both the external and positive external terminals are attached and packaged under the same manufacturing process and conditions as in the embodiment, and the external terminals are shaped. The electrolytic capacitor was completed.
【００１８】上述の実施の形態の方法及び比較例の方法
によって定格容量：１０μＦ、定格電圧：６．３Ｖのチ
ップ型タンタル固体電解コンデンサを１００個ずつ作製
し、１００ｋＨｚでのインピーダンスの絶対値｜Ｚ｜を
測定したところ、実施の形態に係るコンデンサでは｜Ｚ
｜の平均値＝０．６Ωであり、比較例のコンデンサでは
｜Ｚ｜の平均値＝０．８Ωであった。このことから、実
施の形態に係るコンデンサの方が、比較例のコンデンサ
に比べ陰極側の直列抵抗が小いことが分かる。又、イン
ピーダンスの改善度合は、従来例２（特開平５−１４４
６８４号公報）の実施例中の容量１０μＦのチップ型固
体電解コンデンサにおける改善度合と同程度であること
が分かる。更に、同程度のインピーダンス改善効果を得
るための縣濁液中の微粉銀粒子の濃度は、実施の形態で
は５ｗｔ％であるのに対し従来例２では３５ｗｔ％であ
って、実施の形態の方が従来例２に比べて低い濃度で済
むことが分かった。According to the method of the above-described embodiment and the method of the comparative example, 100 chip-type tantalum solid electrolytic capacitors having a rated capacity of 10 μF and a rated voltage of 6.3 V are manufactured, and the absolute value of impedance at 100 kHz | Z When | was measured, | Z was found for the capacitor according to the embodiment.
The average value of | Z = 0.6Ω, and the average value of | Z | = 0.8Ω in the capacitor of the comparative example. This indicates that the capacitor according to the embodiment has a smaller series resistance on the cathode side than the capacitor of the comparative example. Further, the degree of improvement in impedance can be determined by the conventional example 2 (JP-A-5-144).
684) is about the same as the improvement in the chip-type solid electrolytic capacitor having a capacitance of 10 μF in the embodiment. Further, the concentration of the fine silver particles in the suspension for obtaining the same impedance improvement effect is 5 wt% in the embodiment, whereas it is 35 wt% in the conventional example 2, and is higher in the embodiment. However, it was found that a lower concentration was required as compared with Conventional Example 2.
【００１９】ここで、実施の形態において、粒径０．１
μｍ未満の微粉銀粒子が単分散金属粒子となって溶媒に
均一に分散するのは、銀の無機塩を分解して銀粒子を得
る際に、銀粒子の表面に飽和脂肪酸であるミリスチン酸
の−ＯＨ基が反応し、銀粒子表面にミリスチン酸が付着
した状態になって、銀粒子の凝集が妨げられるからであ
ると考えられる。従って、微粉銀粒子の表面をミリスチ
ン酸以外の他の飽和脂肪酸で被覆しても、それら飽和脂
肪酸は銀粒子の凝集を妨げる分散剤としての作用をする
であろう。また、飽和脂肪酸に限らず、−ＯＨ基をもち
一般にＲ−ＯＨで表されるアルコールで銀粒子を被覆し
ても、同様の効果を得ることができるものと推定され
る。しかしながら、本発明は固体電解コンデンサの製造
に関わるものであり、実施の形態で銀層６Ａの焼付けに
用いた２００℃という温度は、固体電解コンデンサの製
造で用いられる各種温度の中でも比較的高い部類に属す
ることを考慮すると、ミリスチン酸の他には、沸点がミ
リスチン酸に近く２００℃程度の温度で分解させことが
できるステアリン酸、ラウリン酸が固体電解コンデンサ
製造用の分散剤として適当であろう。Here, in the embodiment, a particle size of 0.1
The reason that the finely divided silver particles having a particle diameter of less than μm are monodispersed metal particles and are uniformly dispersed in the solvent is that when the inorganic salt of silver is decomposed to obtain silver particles, the surface of the silver particles is formed of a saturated fatty acid myristic acid. This is presumably because the —OH group reacts and myristic acid adheres to the surface of the silver particles, preventing aggregation of the silver particles. Thus, even if the surface of the fine silver particles is coated with a saturated fatty acid other than myristic acid, those saturated fatty acids will act as a dispersant to prevent aggregation of the silver particles. It is also presumed that the same effect can be obtained by coating silver particles with an alcohol having an -OH group and generally represented by R-OH, not limited to saturated fatty acids. However, the present invention relates to the manufacture of a solid electrolytic capacitor, and the temperature of 200 ° C. used for baking silver layer 6A in the embodiment is a relatively high temperature among various temperatures used in the manufacture of a solid electrolytic capacitor. In addition to myristic acid, stearic acid and lauric acid, which have a boiling point close to that of myristic acid and can be decomposed at a temperature of about 200 ° C., will be suitable as dispersants for the production of solid electrolytic capacitors. .
【００２０】[0020]
【発明の効果】以上説明したように、本発明によれば、
陽極体に弁作用金属の粉末から得た焼結体を用い、固体
電解質に二酸化マンガンを用いる固体電解コンデンサを
製造するに当って、粒径が０．１μｍより小なる銀粒子
を用いて、二酸化マンガン層上に銀粒子のみからなる銀
層を直接形成できる。これにより、固体電解コンデンサ
の陰極側の直列抵抗を、より少ない銀粉量で、小さくす
ることができる。As described above, according to the present invention,
Using a sintered body obtained from a valve metal powder for the anode body, and manufacturing a solid electrolytic capacitor using manganese dioxide as the solid electrolyte, using silver particles having a particle size smaller than 0.1 μm, A silver layer consisting of only silver particles can be formed directly on the manganese layer. Thereby, the series resistance on the cathode side of the solid electrolytic capacitor can be reduced with a smaller amount of silver powder.
【図１】本発明の一実施の形態に係るタンタル固体電解
コンデンサにおける、コンデンサ素子の断面を模式的に
示す図である。FIG. 1 is a diagram schematically showing a cross section of a capacitor element in a tantalum solid electrolytic capacitor according to one embodiment of the present invention.
【図２】従来例１のタンタル固体電解コンデンサにおけ
る、コンデンサ素子の断面を模式的に示す図である。FIG. 2 is a diagram schematically showing a cross section of a capacitor element in a tantalum solid electrolytic capacitor of Conventional Example 1.
１ タンタルワイヤ ２ 焼結ペレット ３ 酸化タンタル皮膜 ４ 二酸化マンガン層 ５ カーボン層 ６、６Ａ 銀層 DESCRIPTION OF SYMBOLS 1 Tantalum wire 2 Sintered pellet 3 Tantalum oxide film 4 Manganese dioxide layer 5 Carbon layer 6, 6A Silver layer
Claims (9)
焼結体と、 前記焼結体の表面に形成された誘電体皮膜と、 前記誘電体皮膜上に形成された二酸化マンガン層と、 前記二酸化マンガン層上に直接形成された、銀粒子のみ
からなる銀層とを含む固体電解コンデンサ。1. A sintered body obtained by molding and sintering a powder of a valve metal, a dielectric film formed on a surface of the sintered body, and a manganese dioxide layer formed on the dielectric film. And a silver layer directly formed on the manganese dioxide layer and comprising only silver particles.
ｍ未満の銀粒子を用いて形成されたものであることを特
徴とする固体電解コンデンサ。2. The method according to claim 1, wherein the silver layer has a particle size of 3 nm or more and 100 n.
A solid electrolytic capacitor formed using silver particles of less than m.
とを特徴とする、請求項１又は請求項２に記載の固体電
解コンデンサ。3. The solid electrolytic capacitor according to claim 1, wherein said sintered body is a sintered body of Ta powder.
体を得る工程と、 前記焼結体の表面に誘電体皮膜を形成する工程と、 前記誘電体皮膜上に二酸化マンガン層を形成する工程
と、 前記二酸化マンガン層上に銀粒子のみからなる銀層を直
接形成する工程とを含む固体電解コンデンサの製造方
法。4. A step of forming and sintering a valve metal powder to obtain a sintered body, a step of forming a dielectric film on the surface of the sintered body, and a manganese dioxide layer on the dielectric film. And a step of directly forming a silver layer comprising only silver particles on the manganese dioxide layer.
ガン層形成済みの焼結体を、溶媒と予め分散剤で被覆し
た銀粒子とのみからなる銀粒子の縣濁液に浸漬させ、引
き上げ、所定の温度で焼き付けることにより前記銀粒子
のみからなる銀層を直接二酸化マンガン層上に形成する
ことを特徴とする、請求項４に記載の固体電解コンデン
サの製造方法。5. When forming the silver layer, the sintered body on which the manganese dioxide layer has been formed is immersed in a suspension of silver particles consisting solely of a solvent and silver particles previously coated with a dispersant, and pulled up. The method for manufacturing a solid electrolytic capacitor according to claim 4, wherein the silver layer composed of only the silver particles is directly formed on the manganese dioxide layer by baking at a predetermined temperature.
以上、１００ｎｍ未満の銀粒子を用いることを特徴とす
る、請求項４又は請求項５に記載の固体電解コンデンサ
の製造方法。6. The method according to claim 6, wherein silver particles as a raw material of the silver layer have a particle diameter of 3 nm.
The method for manufacturing a solid electrolytic capacitor according to claim 4 or 5, wherein silver particles having a size of less than 100 nm are used.
特徴とする、請求項５又は請求項６に記載の固体電解コ
ンデンサの製造方法。7. The method for producing a solid electrolytic capacitor according to claim 5, wherein a saturated fatty acid is used as the dispersant.
リン酸及びラウリン酸のいずれか一つを用いることを特
徴とする、請求項７に記載の固体電解コンデンサの製造
方法。8. The method according to claim 7, wherein any one of myristic acid, stearic acid and lauric acid is used as the saturated fatty acid.
とを特徴とする、請求項４乃至８のいずれか一つに記載
の固体電解コンデンサの製造方法。9. The method for manufacturing a solid electrolytic capacitor according to claim 4, wherein Ta powder is used as a raw material of said sintered body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000215595A JP2002033247A (en) | 2000-07-17 | 2000-07-17 | Solid electrolytic capacitor and method of manufacturing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000215595A JP2002033247A (en) | 2000-07-17 | 2000-07-17 | Solid electrolytic capacitor and method of manufacturing the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2002033247A true JP2002033247A (en) | 2002-01-31 |
Family
ID=18710994
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000215595A Pending JP2002033247A (en) | 2000-07-17 | 2000-07-17 | Solid electrolytic capacitor and method of manufacturing the same |
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| Country | Link |
|---|---|
| JP (1) | JP2002033247A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006253169A (en) * | 2005-03-08 | 2006-09-21 | Matsushita Electric Ind Co Ltd | Solid electrolytic capacitor and manufacturing method thereof |
| JP2009252881A (en) * | 2008-04-03 | 2009-10-29 | Nichicon Corp | Solid-state electrolytic capacitor and its manufacturing method |
| KR20130058428A (en) * | 2011-11-25 | 2013-06-04 | 삼성전기주식회사 | Solid electrolyte capacitor and fabrication method thereof |
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|---|---|---|---|---|
| JPS54121270A (en) * | 1978-03-14 | 1979-09-20 | Fukuda Metal Foil Powder | Production of finely divided silver powder |
| JPH09205042A (en) * | 1996-01-26 | 1997-08-05 | Hitachi Aic Inc | Production of tantalum capacitor |
| JPH1088206A (en) * | 1996-09-12 | 1998-04-07 | Dowa Mining Co Ltd | Silver powder and manufacture of silver powder |
| JPH11135377A (en) * | 1997-10-29 | 1999-05-21 | Matsushita Electric Ind Co Ltd | Solid electrolytic capacitor and its manufacture |
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2000
- 2000-07-17 JP JP2000215595A patent/JP2002033247A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54121270A (en) * | 1978-03-14 | 1979-09-20 | Fukuda Metal Foil Powder | Production of finely divided silver powder |
| JPH09205042A (en) * | 1996-01-26 | 1997-08-05 | Hitachi Aic Inc | Production of tantalum capacitor |
| JPH1088206A (en) * | 1996-09-12 | 1998-04-07 | Dowa Mining Co Ltd | Silver powder and manufacture of silver powder |
| JPH11135377A (en) * | 1997-10-29 | 1999-05-21 | Matsushita Electric Ind Co Ltd | Solid electrolytic capacitor and its manufacture |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006253169A (en) * | 2005-03-08 | 2006-09-21 | Matsushita Electric Ind Co Ltd | Solid electrolytic capacitor and manufacturing method thereof |
| JP4670402B2 (en) * | 2005-03-08 | 2011-04-13 | パナソニック株式会社 | Manufacturing method of solid electrolytic capacitor |
| JP2009252881A (en) * | 2008-04-03 | 2009-10-29 | Nichicon Corp | Solid-state electrolytic capacitor and its manufacturing method |
| KR20130058428A (en) * | 2011-11-25 | 2013-06-04 | 삼성전기주식회사 | Solid electrolyte capacitor and fabrication method thereof |
| KR102016481B1 (en) * | 2011-11-25 | 2019-09-02 | 삼성전기주식회사 | Solid Electrolyte Capacitor and fabrication method thereof |
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