JP4653643B2

JP4653643B2 - Element for solid electrolytic capacitor, solid electrolytic capacitor and method for producing the same

Info

Publication number: JP4653643B2
Application number: JP2005337081A
Authority: JP
Inventors: 成友大原; 政幸若月
Original assignee: Nichicon Capacitor Ltd
Current assignee: Nichicon Capacitor Ltd
Priority date: 2005-11-22
Filing date: 2005-11-22
Publication date: 2011-03-16
Anticipated expiration: 2025-11-22
Also published as: JP2007142323A

Description

本発明は、タンタル、ニオブ等の弁作用金属粉末を使用した固体電解コンデンサ用素子、固体電解コンデンサおよ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 element, a solid electrolytic capacitor using a valve action metal powder such as tantalum and niobium, and a method for manufacturing the same.

従来、弁作用金属粉末を用いた固体電解コンデンサ用素子の製造方法は、バインダーを混合した弁作用金属粉末に陽極ワイヤーを埋め込んだ状態で加圧成形する。その後、焼結すると加圧成形した素子の体積が収縮（焼縮み）し、素子内の陽極ワイヤーと焼結体が接合される（例えば、特許文献１参照）。
特開平５−４１３３９号公報 Conventionally, in a method for producing a solid electrolytic capacitor element using a valve metal powder, pressure molding is performed with an anode wire embedded in a valve metal powder mixed with a binder. Thereafter, when sintered, the volume of the press-molded element shrinks (shrinks), and the anode wire and the sintered body in the element are joined (see, for example, Patent Document 1).
JP-A-5-41339

従来の技術では、弁作用金属粉末の焼結後の焼結体と陽極ワイヤーとの接合強度が十分ではないため、接合部分が組立時の外部からの熱的、物理的なストレスに弱くなり、ショート不良率および漏れ電流特性が悪化する問題があった。 In the conventional technology, since the bonding strength between the sintered body after sintering the valve action metal powder and the anode wire is not sufficient, the bonded portion becomes weak against external thermal and physical stress during assembly, There was a problem that the short-circuit defect rate and leakage current characteristics deteriorated.

この接合強度を上げるため、焼結温度を高くし、弁作用金属粉末の焼縮み率を大きくさせる方法がある。しかし、焼結後の焼結体の表面積が減少するため、静電容量が低下するという問題があった。 In order to increase the bonding strength, there is a method of increasing the sintering temperature and increasing the shrinkage rate of the valve action metal powder. However, since the surface area of the sintered body after sintering is reduced, there is a problem that the capacitance is lowered.

本発明は、上記課題を解決するもので、陽極ワイヤーと焼結体の接合性を向上させることで、ショート不良率、漏れ電流特性を改善し、かつ静電容量の低下を抑えた固体電解コンデンサ用素子および当該素子を含む固体電解コンデンサを提供することにある。 The present invention solves the above-mentioned problems, and improves the short-circuit defect rate and leakage current characteristics by improving the bondability between the anode wire and the sintered body, and suppresses the decrease in capacitance. It is providing the element for use and the solid electrolytic capacitor containing the said element.

上記課題を解決するため、本発明の固体電解コンデンサ用素子は、弁作用金属粉末を加圧成形し、焼結した焼結体と陽極ワイヤーとを有する固体電解コンデンサ用素子において、
陽極ワイヤー周辺の内側部分のリンの添加量が外側部分のリンの添加量より少なく、内側部分の焼縮み率が、その外側部分の焼縮み率より大きく、焼縮み率の差が、０．５〜５．０％であることを特徴とする固体電解コンデンサ用素子である。
In order to solve the above problems, the element for a solid electrolytic capacitor of the present invention is the element for a solid electrolytic capacitor having a sintered body and an anode wire obtained by pressure-molding and sintering a valve metal powder.
The addition amount of phosphorus in the inner portion of the peripheral anode wire less than the addition amount of the phosphorus of the outer portion, baked shrinkage of the inner part, rather greater than shrink shrinkage rate of the outer portion, the difference in shrink shrinkage rate, 0. It is 5 to 5.0%, It is an element for solid electrolytic capacitors characterized by the above-mentioned.

さらに、上記の素子を含むことを特徴とする固体電解コンデンサである。 Furthermore, it is a solid electrolytic capacitor characterized by including said element.

ここで、焼縮み率とは、成形体を焼結した後、収縮した割合を示している。具体的には、焼結体の体積と成形体の体積より算出する。
以下に、焼縮み率の算出式を示す。 Here, the shrinkage ratio indicates the ratio of shrinkage after sintering the molded body. Specifically, it is calculated from the volume of the sintered body and the volume of the molded body.
The calculation formula for shrinkage shrinkage is shown below.

［数１］

[Equation 1]

このように、陽極ワイヤー周辺の内側部分の焼縮み率を外側部分より大きくすることで、静電容量の低下がなく、かつショート不良率が低減し、漏れ電流特性の優れた固体電解コンデンサ用素子が得られる。 Thus, by making the shrinkage rate of the inner part around the anode wire larger than that of the outer part, there is no decrease in capacitance, the short-circuit defect rate is reduced, and the element for solid electrolytic capacitors with excellent leakage current characteristics Is obtained.

［実施例１］
以下、本発明の実施例について、図面を参照して説明する。
まず、リンを１２０ｐｐｍ含有したタンタル粉末で陽極ワイヤー周辺の内側部分を成形密度５．５０ｇ／ｃｍ^３で１．２ｍｍ×１．８ｍｍ×０．２ｍｍの大きさに成形した後、その周りの外側部分にリンを１５０ｐｐｍ含有したタンタル粉末で成形密度５．５０ｇ／ｃｍ^３で１．２ｍｍ×１．８ｍｍ×１．０ｍｍの大きさに成形した。次に加圧成形した素子を１４５０℃で焼結し、内側部分の焼縮み率と外側部分の焼縮み率との差を０．５％とした焼結体を作製した。 [Example 1]
Embodiments of the present invention will be described below with reference to the drawings.
First, the inner part around the anode wire was formed with a tantalum powder containing 120 ppm of phosphorus at a molding density of 5.50 g / cm ³ to a size of 1.2 mm × 1.8 mm × 0.2 mm, and then the outer part around it. The tantalum powder containing 150 ppm of phosphorus was molded into a size of 1.2 mm × 1.8 mm × 1.0 mm at a molding density of 5.50 g / cm ³ . Next, the pressure-molded element was sintered at 1450 ° C. to produce a sintered body in which the difference between the shrinkage rate of the inner portion and the shrinkage rate of the outer portion was 0.5%.

その後、焼結体を陽極酸化して、酸化皮膜層を形成し、硝酸マンガン水溶液への含浸、熱分解を複数回繰り返して二酸化マンガンからなる固体電解質層を形成した後、カーボン層、銀層からなる陰極引出層を順次形成した。続いて、陽極リードと陽極リードフレームとを抵抗溶接により接続し、陰極引出層と陰極リードフレームとを導電性接着剤で接続した後、トランスファーモールドにより樹脂外装し、定格４Ｖ−１００μＦの固体電解コンデンサを作製した。 Thereafter, the sintered body is anodized to form an oxide film layer, impregnation into an aqueous manganese nitrate solution, and thermal decomposition are repeated a plurality of times to form a solid electrolyte layer made of manganese dioxide, and then from the carbon layer and the silver layer. The cathode lead layers were sequentially formed. Subsequently, the anode lead and the anode lead frame are connected by resistance welding, the cathode lead layer and the cathode lead frame are connected by a conductive adhesive, and then resin-coated with a transfer mold, and a solid electrolytic capacitor having a rating of 4V-100 μF. Was made.

［実施例２］
リンを１００ｐｐｍ含有したタンタル粉末で陽極ワイヤー周辺の内側部分を成形し、内側部分の焼縮み率と外側部分の焼縮み率との差を１．０％とした焼結体を作製した以外は、実施例１と同様の方法で固体電解コンデンサを作製した。 [Example 2]
Except that the inner part around the anode wire was formed with tantalum powder containing 100 ppm of phosphorus, and a sintered body was prepared in which the difference between the shrinkage rate of the inner part and the shrinkage rate of the outer part was 1.0%. A solid electrolytic capacitor was produced in the same manner as in Example 1.

［実施例３］
リンを６０ｐｐｍ含有したタンタル粉末で陽極ワイヤー周辺の内側部分を成形し、内側部分の焼縮み率と外側部分の焼縮み率との差を５．０％とした焼結体を作製した以外は、実施例１と同様の方法で固体電解コンデンサを作製した。 [Example 3]
Except that the inner part around the anode wire was formed with tantalum powder containing 60 ppm of phosphorus, and a sintered body was prepared in which the difference between the shrinkage rate of the inner part and the shrinkage rate of the outer part was 5.0%. A solid electrolytic capacitor was produced in the same manner as in Example 1.

［比較例１］
リンを１４０ｐｐｍ含有したタンタル粉末で陽極ワイヤー周辺の内側部分を成形し、内側部分の焼縮み率と外側部分の焼縮み率との差を０．１％とした焼結体を作製した以外は、実施例１と同様の方法で固体電解コンデンサを作製した。 [Comparative Example 1]
Except that the inner part around the anode wire was formed with tantalum powder containing 140 ppm of phosphorus, and a sintered body was prepared in which the difference between the shrinkage rate of the inner part and the shrinkage rate of the outer part was 0.1%. A solid electrolytic capacitor was produced in the same manner as in Example 1.

［比較例２］
リンを４０ｐｐｍ含有したタンタル粉末で陽極ワイヤー周辺の内側部分を成形した後焼結し、内側部分の焼縮み率と外側部分の焼縮み率との差を６．０％とした焼結体を作製した以外は、実施例１と同様の方法で固体電解コンデンサを作製した。 [Comparative Example 2]
After forming the inner part around the anode wire with tantalum powder containing 40 ppm of phosphorus, sintering is performed to produce a sintered body with a difference between the shrinkage rate of the inner part and the shrinkage ratio of the outer part of 6.0% A solid electrolytic capacitor was produced in the same manner as in Example 1 except that.

（従来例１）
リンを１５０ｐｐｍ含有したタンタル粉末のみを用い、内側部分と外側部分に分けず、１回で成形した後焼結し、内側部分の焼縮み率と外側部分の焼縮み率との差がない焼結体を作製した以外は、実施例１と同様の方法で固体電解コンデンサを作製した。 (Conventional example 1)
Using only tantalum powder containing 150 ppm of phosphorus, without dividing the inner part and the outer part, sintering after molding after one molding, there is no difference between the shrinkage rate of the inner part and the shrinkage rate of the outer part A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the body was produced.

（従来例２）
リンを１２０ｐｐｍ含有したタンタル粉末のみを用い、内側部分と外側部分に分けず、１回で成形した後焼結し、内側部分の焼縮み率と外側部分の焼縮み率との差がない焼結体を作製した以外は、実施例１と同様の方法で固体電解コンデンサを作製した。 (Conventional example 2)
Using only tantalum powder containing 120 ppm of phosphorus, without dividing the inner part and the outer part, sintering after molding once, and there is no difference between the shrinkage rate of the inner part and the shrinkage rate of the outer part A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the body was produced.

上記実施例１〜３、比較例１、２および従来例１、２により作製した固体電解コンデンサの電気特性を測定した。結果を表１に示す。

The electrical characteristics of the solid electrolytic capacitors produced according to Examples 1 to 3, Comparative Examples 1 and 2 and Conventional Examples 1 and 2 were measured. The results are shown in Table 1.

表１から明らかなように、実施例１〜３は、従来例１と比較すると、静電容量は同等でありながら、ショート不良率、漏れ電流不良率ともに低く、改善効果が見られる。また、従来例２と比較し、静電容量の低下もない。
ただし、焼結体の内側部分と外側部分の焼縮み率の差を０．１％とした場合（比較例１）は、ショート不良率、漏れ電流不良率とも高くなり、６．０％とした場合（比較例２）は、静電容量が低下傾向にあるため好ましくない。
以上より、焼結体の内側部分と外側部分の焼縮み率の差は０．５〜５．０％が望ましい。 As can be seen from Table 1, Examples 1 to 3 have the same capacitance, but both the short-circuit defect rate and the leakage current defect rate are low compared to Conventional Example 1, and an improvement effect is seen. Further, there is no decrease in capacitance as compared with Conventional Example 2.
However, when the difference in shrinkage rate between the inner part and the outer part of the sintered body is 0.1% (Comparative Example 1), both the short-circuit defect rate and the leakage current defect rate are increased to 6.0%. The case (Comparative Example 2) is not preferable because the capacitance tends to decrease.
As mentioned above, 0.5 to 5.0% of the difference of the shrinkage rate of the inner part and outer part of a sintered compact is desirable.

また、成形体の内側部分の体積は、成形体全体の体積に対し、１０．０〜２０．０％とすることが望ましい。１０．０％未満では、本発明の効果が十分に得られず、２０．０％を超えると、静電容量が低下するおそれがある。 In addition, the volume of the inner part of the molded body is desirably 10.0 to 20.0% with respect to the volume of the entire molded body. If it is less than 10.0%, the effect of the present invention cannot be sufficiently obtained, and if it exceeds 20.0%, the capacitance may be lowered.

さらに、実施例では、弁作用金属粉末としてタンタルを用いたが、ニオブを使用しても同様の効果が得られる。 Furthermore, in the examples, tantalum was used as the valve action metal powder, but the same effect can be obtained even if niobium is used.

実施例１の固体電解コンデンサ用素子の断面図。1 is a cross-sectional view of a solid electrolytic capacitor element of Example 1. FIG. 従来例１の固体電解コンデンサ用素子の断面図。Sectional drawing of the element for solid electrolytic capacitors of the prior art example 1. FIG.

Explanation of symbols

１陽極ワイヤー
２焼縮み率の大きい内側部分
３焼縮み率の小さい外側部分
４一種類の弁作用金属粉末のみ使用した素子 DESCRIPTION OF SYMBOLS 1 Anode wire 2 Inner part 3 with large shrinkage rate Outer part 4 with small shrinkage rate Element using only one kind of valve metal powder

Claims

In an element for a solid electrolytic capacitor having a sintered body and an anode wire formed by pressure-molding and sintering a valve metal powder,
The addition amount of phosphorus in the inner portion of the peripheral anode wire less than the addition amount of the phosphorus of the outer portion, baked shrinkage of the inner part, rather greater than shrink shrinkage rate of the outer portion, the difference in shrink shrinkage rate, 0. The element for solid electrolytic capacitors, characterized by being 5 to 5.0% .

A solid electrolytic capacitor comprising the element for a solid electrolytic capacitor according to claim 1.