JP5088521B2 - Aluminum electrolytic capacitor - Google Patents

Aluminum electrolytic capacitor Download PDF

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JP5088521B2
JP5088521B2 JP2011055266A JP2011055266A JP5088521B2 JP 5088521 B2 JP5088521 B2 JP 5088521B2 JP 2011055266 A JP2011055266 A JP 2011055266A JP 2011055266 A JP2011055266 A JP 2011055266A JP 5088521 B2 JP5088521 B2 JP 5088521B2
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lead wire
insertion hole
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round bar
lead
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JP2011155279A (en
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直人 岩野
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Elna Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/08—Housing; Encapsulation
    • H01G9/10—Sealing, e.g. of lead-in wires
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/008—Terminals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/04—Electrodes or formation of dielectric layers thereon
    • H01G9/042—Electrodes or formation of dielectric layers thereon characterised by the material
    • H01G9/045—Electrodes or formation of dielectric layers thereon characterised by the material based on aluminium

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  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Electric Double-Layer Capacitors Or The Like (AREA)
  • Fixed Capacitors And Capacitor Manufacturing Machines (AREA)

Description

本発明は、アルミニウム電解コンデンサに関し、さらに詳しく言えば、リード端子の鉛フリー化に伴って発生するＳｎ（錫）ウィスカ対策に関するものである。   The present invention relates to an aluminum electrolytic capacitor, and more particularly, to a countermeasure against Sn (tin) whisker that occurs with lead-free lead terminals.

アルミニウム電解コンデンサでは、コンデンサ素子を構成するアルミニウム材からなる陽極箔と陰極箔とにリード端子が取り付けられ、そのリード端子が外装ケースの開口部を封止している封口体を貫通して外部に引き出される。   In an aluminum electrolytic capacitor, a lead terminal is attached to an anode foil and a cathode foil made of an aluminum material constituting a capacitor element, and the lead terminal passes through a sealing body that seals an opening of an exterior case to the outside. Pulled out.

通常、リード端子には、アルミニウムの棒材の一端側に羽子板状に押し潰された扁平部を有し、他端側が丸棒部とされたタブ端子が用いられるが、回路基板にはんだ付け可能とするため、タブ端子の丸棒部には、外部引出リード線として表面にメッキ層を有する銅被覆鋼線（ＣＰ線）が溶接される。   Usually, the lead terminal is a tab terminal that has a flat portion crushed in the shape of a feather plate on one end of an aluminum bar, and the other end is a round bar, but can be soldered to the circuit board Therefore, a copper-coated steel wire (CP wire) having a plating layer on the surface is welded to the round bar portion of the tab terminal as an external lead wire.

近年の環境保護の観点から、リード端子においても鉛フリー化に対応するため、多くの場合、Ｓｎ１００％メッキの銅被覆鋼線が用いられている。そのＳｎメッキ厚は１２μｍ程度で、通常、その表面からＳｎのウィスカ（ヒゲ状の結晶体）の発生は見られない。   From the viewpoint of environmental protection in recent years, in order to cope with lead-free lead terminals as well, a copper-coated steel wire plated with Sn 100% is often used. The Sn plating thickness is about 12 μm, and usually no Sn whisker (whisker-like crystal) is generated from the surface.

しかしながら、タブ端子の丸棒部と外部引出リード線との溶接部では、Ａｌ，Ｓｎ，Ｃｕ，Ｆｅなどが混在し、特にアルミニウム層が外気に晒されると、水和や酸化反応などによりＳｎ層に応力が働き、Ｓｎウィスカが猛烈な勢いで発生することが知られている。   However, Al, Sn, Cu, Fe, and the like are mixed in the welded portion of the round terminal portion of the tab terminal and the external lead wire, and particularly when the aluminum layer is exposed to the outside air, the Sn layer is caused by hydration or oxidation reaction. It is known that the stress acts on the Sn whisker and the Sn whisker is generated with a tremendous momentum.

リード端子は、封口体に穿設されている端子挿通孔を通して外部に引き出されるが、従来において、端子挿通孔はその全体が上記丸棒部とほぼ同一径であり、溶接部が外部に露出し外気に晒される構造とされているため、Ｓｎウィスカが成長しやすく、また、その成長が著しい場合には、ウィスカが回路基板上に飛散し、最悪の場合、電子回路をショートさせる危険性がある。   The lead terminal is pulled out to the outside through a terminal insertion hole formed in the sealing body. Conventionally, the terminal insertion hole has the same diameter as that of the round bar portion, and the welded portion is exposed to the outside. Since the structure is exposed to the outside air, Sn whiskers are likely to grow. When the growth is remarkable, the whiskers are scattered on the circuit board, and in the worst case, there is a risk of shorting the electronic circuit. .

Ｓｎウィスカの発生原因となる異種金属のＳｎへの応力を緩和するため、例えば特許文献１に記載の発明では、メッキ層となるＳｎにＢｉ（ビスマス）を含有させることが提案されている。これによれば、Ｓｎウィスカの成長がある程度抑えられるものの、すべてのリード端子について、同じ効果が得られるまでには至っていない。   In order to relieve stress on Sn of dissimilar metals that cause Sn whiskers, for example, in the invention described in Patent Document 1, it is proposed to contain Bi (bismuth) in Sn that becomes a plating layer. According to this, although the growth of Sn whisker can be suppressed to some extent, the same effect has not been obtained for all the lead terminals.

特開２０００−１２３８６号公報JP 2000-12386 A

したがって、本発明の課題は、封口体にほとんどコストアップを伴わない工夫を加えることにより、Ｓｎウィスカの成長を押さえ込み、仮にＳｎウィスカが発生したとしても、外部に飛散しないようにすることにある。   Therefore, an object of the present invention is to suppress the growth of Sn whiskers by adding a device that hardly increases the cost to the sealing body, so that even if Sn whiskers are generated, they are not scattered outside.

上記課題を解決するため、請求項１に記載の発明は、ともにリード端子が取り付けられたアルミニウム材からなる陽極箔と陰極箔とをセパレータを介して巻回してなるコンデンサ素子と、上記コンデンサ素子が所定の電解物質とともに収納される有底筒状の外装ケースと、上記リード端子用の端子挿通孔が穿設されていて上記外装ケースの開口部に装着される封口ゴムとを含み、上記リード端子が、扁平部と丸棒部とを有するアルミニウム材からなるタブ端子と、表面に鉛を含まず錫を含むメッキ層を有し上記丸棒部の端部に溶接された外部引出リード線とを備え、上記リード端子が上記端子挿通孔内に挿通され、上記外部引出リード線が上記外装ケース外に引き出されるアルミニウム電解コンデンサにおいて、上記封口ゴムの端子挿通孔には、上記タブ端子の丸棒部が嵌合される丸棒嵌合孔と、上記丸棒嵌合孔に連通していて上記外部引出リード線が挿通されるリード線挿通孔とが含まれ、かつ、上記丸棒嵌合孔と上記リード線挿通孔との間に、上記丸棒部と上記外部引出リード線との溶接部が収納される溶接部収納部を備え、上記メッキ層に含まれている錫に起因する上記溶接部でのウィスカの発生および成長を抑制するとともに上記ウィスカの外部への漏出を防止するため、上記リード線挿通孔の孔径が上記外部引出リード線の直径よりも小径で上記溶接部が外気に晒されないように外部と遮断されているとともに、上記溶接収納部が上記溶接部に密着する漏斗状に形成されており、かつ、上記リード線挿通孔の軸長が０．２ｍｍ以上であることを特徴としている。
In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a capacitor element formed by winding an anode foil and a cathode foil made of an aluminum material each having a lead terminal attached thereto via a separator, and the capacitor element The lead terminal includes a bottomed cylindrical outer case that is stored together with a predetermined electrolytic substance, and a sealing rubber that is provided with a terminal insertion hole for the lead terminal and is attached to an opening of the outer case. but the tab terminal made of aluminum material having a flat portion and a round bar portion, and a lead-out lead wire welded to an end portion of the round bar portion having a plating layer containing tin free of lead in the surface An aluminum electrolytic capacitor in which the lead terminal is inserted into the terminal insertion hole, and the external lead wire is drawn out of the outer case, in the terminal insertion hole of the sealing rubber. A round bar fitting hole round bar portion of the tab terminal is fitted, the outer lead leads in communication with the rod fitting hole includes a lead wire insertion hole to be inserted, and And a welded portion storage portion for storing a welded portion between the round bar portion and the external lead wire between the round bar fitting hole and the lead wire insertion hole, and is included in the plating layer. for thereby suppressing the occurrence and growth of whiskers at the weld due to tin are to prevent leakage to the outside of the whiskers, smaller diameter than the diameter of the upper Kigaibu lead leads diameter of the lead wire insertion hole in conjunction with the welding portion is isolated from the outside so as not to be exposed to the air, the welding housing portion is formed in a leakage DOO shape you close contact with the welded portion, and the axial length of the lead wire insertion hole Is 0.2 mm or more .

請求項２に記載の発明は、上記請求項１において、上記リード線挿通孔の孔径が、上記外部引出リード線の直径に対して８０〜９０％であることを特徴としている。
According to a second aspect of the present invention, in the first aspect, the lead wire insertion hole has a hole diameter of 80 to 90 % with respect to the diameter of the external lead wire.

請求項３に記載の発明は、上記請求項１または２において、上記リード線挿通孔の軸長が上記封口ゴムの厚さの２０％以上であることを特徴としている。
According to a third aspect of the present invention, in the first or second aspect , the axial length of the lead wire insertion hole is 20% or more of the thickness of the sealing rubber.

請求項１に記載の発明によれば、封口ゴムの端子挿通孔に、タブ端子の丸棒部が嵌合される丸棒嵌合孔と、丸棒嵌合孔に連通していて外部引出リード線が挿通されるリード線挿通孔とを含ませ、リード線挿通孔の孔径を外部引出リード線の直径よりも小径としたことにより、外部引出リード線の溶接部が外部と遮断され、外気に直接的に晒されないため、Ｓｎメッキ層を有する場合におけるＳｎウィスカの発生を抑制することができる。また、丸棒嵌合孔とリード線挿通孔との間に外部引出リード線の溶接部に密着するように形成された漏斗状の溶接部収納部を備えることにより、仮にＳｎウィスカが発生したとしても、その成長を押さえ込むことができる。また、リード線挿通孔の軸長を０．２ｍｍ以上とすることにより、Ｓｎウィスカが最大に成長したとしても、封口ゴムが突き破られることがない。
According to the first aspect of the present invention, a round bar fitting hole into which the round bar portion of the tab terminal is fitted into the terminal insertion hole of the sealing rubber, and the external lead is connected to the round bar fitting hole. The lead wire insertion hole through which the wire is inserted is included, and the diameter of the lead wire insertion hole is made smaller than the diameter of the external lead wire. Since it is not directly exposed, it is possible to suppress the generation of Sn whiskers when the Sn plating layer is provided. Moreover, it is assumed that Sn whisker is generated by providing a funnel-shaped welded portion storage portion formed so as to be in close contact with the welded portion of the external lead wire between the round bar fitting hole and the lead wire insertion hole. But it can hold back its growth. Moreover, even if Sn whisker grows to the maximum by setting the axial length of the lead wire insertion hole to 0.2 mm or more, the sealing rubber is not pierced.

リード線挿通孔の孔径を外部引出リード線の直径に対して８０〜９０％とする請求項２に記載の発明によれば、リード線を折り曲げることなく、また、コンデンサ素子に対してストレスをかけることなく、外部引出リード線をリード線挿通孔に挿通することができる。
According to the invention of claim 2, the lead wire insertion hole has a hole diameter of 80 to 90 % of the diameter of the external lead wire, and stress is applied to the capacitor element without bending the lead wire. Without this, the external lead wire can be inserted into the lead wire insertion hole.

リード線挿通孔の軸長を封口ゴムの厚さの２０％以上とする請求項３に記載の発明によれば、封口ゴムの封止性を良好に維持でき、また、組立時の生産性を良好なものとすることができる。
According to the invention of claim 3 , wherein the lead wire insertion hole has an axial length of 20% or more of the thickness of the sealing rubber, the sealing property of the sealing rubber can be maintained satisfactorily, and the productivity at the time of assembly can be increased. It can be good.

本発明のアルミニウム電解コンデンサの基本的な構成を示す模式的な断面図。The typical sectional view showing the basic composition of the aluminum electrolytic capacitor of the present invention. 上記アルミニウム電解コンデンサに用いられるリード端子を示す斜視図。The perspective view which shows the lead terminal used for the said aluminum electrolytic capacitor. 本発明の要部を示す断面図。Sectional drawing which shows the principal part of this invention. Ｓｎウィスカの成長長さを示すグラフ。The graph which shows the growth length of Sn whisker. 長さが３０μｍ以上のＳｎウィスカ発生率を示す示すグラフ。The graph which shows Sn whisker incidence rate whose length is 30 micrometers or more.

次に、図面を参照して、本発明の実施形態について説明するが、本発明はこれに限定されるものではない。   Next, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

図１の断面図に示すように、このアルミニウム電解コンデンサは、一対のリード端子２，２を有するコンデンサ素子１を備える。コンデンサ素子１は、図２に示すように、リード端子２が取り付けられたアルミニウム材からなる陽極箔１ａと陰極箔１ｂとを図示しないセパレータ紙を介して渦巻き状に巻回することにより形成される。   As shown in the sectional view of FIG. 1, this aluminum electrolytic capacitor includes a capacitor element 1 having a pair of lead terminals 2 and 2. As shown in FIG. 2, the capacitor element 1 is formed by winding an anode foil 1a made of an aluminum material to which lead terminals 2 are attached and a cathode foil 1b in a spiral shape through a separator paper (not shown). .

コンデンサ素子１は、有底円筒状の外装ケース３内に所定の電解物質を伴って収納され、外装ケース３の開口部は、封口ゴム４によって封口される。封口ゴム４には、端子挿通孔５，５が穿設されており、この端子挿通孔５，５を通してリード端子２，２の各先端部が外部に引き出される。   The capacitor element 1 is accommodated in a bottomed cylindrical outer case 3 with a predetermined electrolytic substance, and the opening of the outer case 3 is sealed with a sealing rubber 4. The sealing rubber 4 is provided with terminal insertion holes 5 and 5, and the tip ends of the lead terminals 2 and 2 are drawn out through the terminal insertion holes 5 and 5.

実際には、封口ゴム４は先にリード端子２，２に取り付けられた状態で、コンデンサ素子１とともに外装ケース３内に収納され、その後形成される外装ケース３の横絞り溝３ａと、外装ケース３の端縁３ｂのかしめによって外装ケース３の開口部内に気密的に固定される。   Actually, the sealing rubber 4 is housed in the outer case 3 together with the capacitor element 1 in the state of being attached to the lead terminals 2 and 2, and then formed in the lateral throttle groove 3a of the outer case 3 and the outer case. 3 is fixed airtightly in the opening of the outer case 3 by caulking of the edge 3b.

外装ケース３は、通常よく用いられるアルミニウムケースであってよい。封口ゴム４には、ブチルゴムなどが用いられてよく、特殊なゴム材である必要はない。また、電解物質には、通常、水系もしくは有機系の液状電解質が用いられるが、固体電解質が用いられてもよい。   The exterior case 3 may be a commonly used aluminum case. Butyl rubber or the like may be used for the sealing rubber 4 and does not need to be a special rubber material. The electrolyte substance is usually a water-based or organic liquid electrolyte, but a solid electrolyte may also be used.

図２に示すように、リード端子２には、タブ端子２１と外部引出リード線２２とが含まれている。タブ端子２１はアルミニウム材からなり、羽子板状にプレス成型された扁平部２１ａと丸棒部２１ｂとを備える。   As shown in FIG. 2, the lead terminal 2 includes a tab terminal 21 and an external lead wire 22. The tab terminal 21 is made of an aluminum material, and includes a flat portion 21a and a round bar portion 21b that are press-molded into a battledore shape.

この種のタブ端子２１は、アルミニウムの丸棒材を所定長さに切断し、その一端側をプレスすることにより得ることができ、扁平部２１ａがかしめ針もしくは溶接などにより陽極箔１ａと陰極箔１ｂとに取り付けられる。   This type of tab terminal 21 can be obtained by cutting a round aluminum bar material to a predetermined length and pressing one end thereof, and the flat portion 21a is caulking needle or welded to the anode foil 1a and the cathode foil. 1b.

外部引出リード線２２には、通常、銅被覆鋼線（ＣＰ線）が用いられる。外部引出リード線２２は、回路基板に対するハンダ付け性を良好とするため、表面にメッキ層を備えるが、Ｐｂ（鉛）フリー化の場合、そのメッキ層には主としてＳｎ１００％メッキもしくはＳｎ／Ｂｉ（０．５％）メッキなどが適用される。   For the external lead wire 22, a copper-coated steel wire (CP wire) is usually used. The external lead 22 is provided with a plating layer on the surface in order to improve the solderability to the circuit board. However, in the case of Pb (lead) free, the plating layer is mainly Sn 100% plated or Sn / Bi ( 0.5%) plating or the like is applied.

外部引出リード線２２は、タブ端子２１の丸棒部２１ｂよりも小径で、丸棒部２１ｂのの端面に溶接される。その溶接部に参照符号２３を付す。表面のメッキ層がＳｎ１００％メッキである場合、溶接部２３以外のメッキ層は安定しているが、溶接部２３では、Ａｌ，Ｓｎ，Ｃｕ，Ｆｅなどが混在しており、外気に晒されると、Ａｌの水和や酸化反応によりＳｎ層に応力が働き、Ｓｎウィスカ（ヒゲ状の結晶体）２３ａが猛烈な勢いで発生し成長する。Ｓｎ／Ｂｉ（０．５％）メッキにおいても、Ｓｎ１００％よりはウィスカの成長は緩和されるが、同様にウィスカは発生する。   The external lead wire 22 has a smaller diameter than the round bar portion 21b of the tab terminal 21 and is welded to the end surface of the round bar portion 21b. Reference numeral 23 is attached to the weld. When the plating layer on the surface is Sn 100% plating, the plating layer other than the welded portion 23 is stable, but in the welded portion 23, Al, Sn, Cu, Fe, etc. are mixed and exposed to the outside air. Then, stress acts on the Sn layer due to the hydration or oxidation reaction of Al, and Sn whisker (beard-like crystal) 23a is generated and grows with a tremendous momentum. In Sn / Bi (0.5%) plating, whisker growth is mitigated as compared with Sn 100%, but whisker is generated.

溶接部２３でのＳｎウィスカ２３ａの発生および成長を抑えるため、本発明では、端子挿通孔５を図３に示すような構成とする。図３はリード端子２の溶接部２３の部分とともに端子挿通孔５を拡大して示す断面図で、端子挿通孔５は、丸棒部２１ｂが嵌合される大径の丸棒嵌合孔５１と、外部引出リード線２２が挿通される小径のリード線挿通孔５２と、それらの間に形成される溶接部収納部５３とを備える。   In order to suppress the generation and growth of Sn whiskers 23a in the welded portion 23, the terminal insertion hole 5 is configured as shown in FIG. FIG. 3 is an enlarged cross-sectional view of the terminal insertion hole 5 together with the welded portion 23 of the lead terminal 2. The terminal insertion hole 5 is a large-diameter round bar fitting hole 51 into which the round bar part 21b is fitted. And a small-diameter lead wire insertion hole 52 through which the external lead wire 22 is inserted, and a welded portion storage portion 53 formed therebetween.

丸棒嵌合孔５１，溶接部収納部５３およびリード線挿通孔５２は、同軸的に連通している。丸棒嵌合孔５１は、丸棒部２１ｂの直径とほぼ同径もしくは若干小径の孔であってよい。これに対して、リード線挿通孔５２は、溶接部２３を外部と遮断するため、外部引出リード線２２よりも小径とする。   The round bar fitting hole 51, the welded portion storage portion 53, and the lead wire insertion hole 52 are coaxially connected. The round bar fitting hole 51 may be a hole having a diameter substantially the same as or slightly smaller than the diameter of the round bar portion 21b. On the other hand, the lead wire insertion hole 52 has a smaller diameter than the external lead wire 22 in order to block the welded portion 23 from the outside.

リード線挿通孔５２を小径にするにしても、あまり小さくすると、外部引出リード線２２を挿通する際に、リード線が折れ曲がったり、コンデンサ素子１にストレスが加わり特性劣化を引き起こすおそれがあるため、外部引出リード線２２の直径をφ１，リード線挿通孔５２の内径をφ２として、φ２はφ１の７０〜９９．９％（特には８０〜９０％）であることが好ましい。なお、リード線の挿通性を良好とするには、リード線の先端部を加熱溶融して丸みを付けることも有効である。   Even if the lead wire insertion hole 52 has a small diameter, if the lead wire insertion hole 52 is too small, the lead wire may be bent or the capacitor element 1 may be stressed when the external lead wire 22 is inserted. The diameter of the external lead wire 22 is φ1 and the inner diameter of the lead wire insertion hole 52 is φ2, and φ2 is preferably 70 to 99.9% (particularly 80 to 90%) of φ1. In order to improve the lead wire insertion property, it is also effective to heat and melt the tip of the lead wire to round it.

また、Ｓｎウィスカ２３ａは、６０℃，相対湿度９５％，１０００時間の耐湿貯蔵で最大２００μｍまで成長することが知られている。このため、リード線挿通孔５２の軸長（深さ）Ｌは、０．２ｍｍ以上であることが好ましい。このことは、リード端子２を端子挿通孔５内に挿通した場合、溶接部２３の下端から封口ゴム４の下面までの肉厚が０．２ｍｍ以上必要であることを意味している。   Further, it is known that the Sn whisker 23a grows up to a maximum of 200 μm in a moisture-resistant storage at 60 ° C., a relative humidity of 95%, and 1000 hours. For this reason, it is preferable that the axial length (depth) L of the lead wire insertion hole 52 is 0.2 mm or more. This means that when the lead terminal 2 is inserted into the terminal insertion hole 5, the thickness from the lower end of the welded portion 23 to the lower surface of the sealing rubber 4 is required to be 0.2 mm or more.

なお、リード線挿通孔５２での封止性および組立時の生産性の観点からすれば、リード線挿通孔５２の軸長Ｌは、封口ゴム４の厚さの２０％以上とすることが好ましい。   From the viewpoint of sealing performance at the lead wire insertion hole 52 and productivity during assembly, the axial length L of the lead wire insertion hole 52 is preferably 20% or more of the thickness of the sealing rubber 4. .

溶接部収納部５３は、Ｓｎウィスカ２３ａの発生および成長を抑制するため、大径の丸棒嵌合孔５１と小径のリード線挿通孔５２との間で、溶接部２３に密着するように漏斗状に形成される。   In order to suppress generation and growth of the Sn whisker 23a, the welded portion storage portion 53 is a funnel so as to be in close contact with the welded portion 23 between the large-diameter round bar fitting hole 51 and the small-diameter lead wire insertion hole 52. It is formed in a shape.

上記した構成によれば、リード端子２を端子挿通孔５に挿通すると、リード線挿通孔５２により溶接部２３が外部と遮断され、また、溶接部２３には溶接部収納部５３の内面が密着することになるため、溶接部２３でのＳｎウィスカ２３ａが発生しにくくなり、仮にＳｎウィスカ２３ａが発生したとしても、その成長が押さえ込まれ、コンデンサ外部に飛散するまでには至らない。したがって、回路基板に実装した場合、長期にわたって電子回路のショート発生を未然に防止することができる。   According to the configuration described above, when the lead terminal 2 is inserted into the terminal insertion hole 5, the welded portion 23 is blocked from the outside by the lead wire insertion hole 52, and the inner surface of the welded portion storage portion 53 is in close contact with the welded portion 23. Therefore, the Sn whisker 23a is hardly generated in the welded portion 23, and even if the Sn whisker 23a is generated, its growth is suppressed and does not reach the outside of the capacitor. Therefore, when mounted on a circuit board, it is possible to prevent the occurrence of a short circuit in the electronic circuit over a long period of time.

図３を参照して、本発明例として、リード端子２の外部引出リード線２２に、表面にＳｎ１００％のメッキ層を有する直径０．４５ｍｍの銅被覆鋼線を用い、端子挿通孔５のリード線挿通孔５２の内径を０．３６ｍｍ（０．４５ｍｍの８０％）として、１０Ｖ１００μＦ（外径６．３ｍｍ，軸長５．０ｍｍ）のアルミニウム電解コンデンサを２０個試作した。   Referring to FIG. 3, as an example of the present invention, a lead-coated lead wire 22 of lead terminal 2 is made of a copper-coated steel wire having a diameter of 100% Sn and a copper-coated steel wire having a diameter of 0.45 mm. Twenty aluminum electrolytic capacitors of 10V 100 μF (outer diameter 6.3 mm, axial length 5.0 mm) were made on trial with the inner diameter of the wire insertion hole 52 being 0.36 mm (80% of 0.45 mm).

比較例は、端子挿通孔５が全長にわたって丸棒部２１ｂとほぼ同一径で溶接部２３が外部に露出している１０Ｖ１００μＦ（外径６．３ｍｍ，軸長５．０ｍｍ）のアルミニウム電解コンデンサである（試作数２０個）。   The comparative example is an aluminum electrolytic capacitor of 10 V 100 μF (outer diameter 6.3 mm, axial length 5.0 mm) in which the terminal insertion hole 5 is almost the same diameter as the round bar portion 21b over the entire length and the welded portion 23 is exposed to the outside. (20 prototypes).

本発明例および比較例ともに、６０℃，相対湿度９５％，１０００時間の耐湿貯蔵試験を行って、Ｓｎウィスカの成長および長さが３０μｍ以上のＳｎウィスカ発生率を観測した。この観測は、２００時間，４００時間，６００時間，８００時間，１０００時間ごとに行ったが、本発明例では外部から溶接部が見えないため、各時間ごとに４個を抽出し、溶接部２３を覆っているゴムを取り除いてウィスカの長さを計測した。   Both the inventive example and the comparative example were subjected to a moisture-resistant storage test at 60 ° C., a relative humidity of 95%, and 1000 hours, and the growth of Sn whiskers and the occurrence rate of Sn whiskers having a length of 30 μm or more were observed. This observation was performed every 200 hours, 400 hours, 600 hours, 800 hours, and 1000 hours. However, in the example of the present invention, since the welded portion cannot be seen from the outside, four pieces are extracted every time, and the welded portion 23 is extracted. The length of whisker was measured by removing the rubber covering.

Ｓｎウィスカの長さの観測結果を図４に示す。これから分かるように、比較例では溶接部２３が湿度雰囲気に晒されているため、溶接部２３でのＳｎメッキ層に対する応力が働き、Ｓｎウィスカの成長が激しく、８００時間経過時点で２００μｍにも達した。これに対して、本発明例では溶接部２３が湿度雰囲気と遮断されているため、Ｓｎウィスカの最大長さは比較例の１／６程度に抑えられ、溶接部２３が直接外気に触れていない効果がでている。   The observation result of the length of Sn whisker is shown in FIG. As can be seen, in the comparative example, since the welded portion 23 is exposed to a humidity atmosphere, the stress on the Sn plating layer at the welded portion 23 acts, and the growth of Sn whiskers is intense, reaching 200 μm after 800 hours. did. On the other hand, in the example of the present invention, since the welded portion 23 is cut off from the humidity atmosphere, the maximum length of the Sn whisker is suppressed to about 1/6 of the comparative example, and the welded portion 23 does not directly contact the outside air. There is an effect.

次に、長さが３０μｍ以上のＳｎウィスカ発生率の観測結果を図５に示す。比較例では、時間を追って長さが３０μｍ以上のＳｎウィスカ発生率が増え、８００時間経過時点では、その発生率が約６０％にも達した。これに対して、本発明例では、４００時間経過後で長さが３０μｍ以上のＳｎウィスカ発生率は約５％であり、その後はＳｎウィスカが成長せず、１０００時間に至るまで、発生率約５％を維持している。   Next, FIG. 5 shows the observation results of the incidence rate of Sn whiskers having a length of 30 μm or more. In the comparative example, the incidence rate of Sn whisker having a length of 30 μm or more increased with time, and the occurrence rate reached about 60% when 800 hours passed. On the other hand, in the example of the present invention, the occurrence rate of Sn whisker having a length of 30 μm or more after about 400 hours is about 5%, and thereafter the Sn whisker does not grow and the occurrence rate is about 1000 hours. 5% is maintained.

以上説明したように、本発明によれば、Ｐｂフリー化の要請から、外部引出リード線に例えばＳｎ１００％メッキのリード線を使用する場合に問題とされていたウィスカの成長を押さえ込み、仮にＳｎウィスカが発生したとしても、外部に飛散しないようにすることができるため、回路基板に長期間にわたって安心して実装できる高信頼性のアルミニウム電解コンデンサが提供され、その産業上の利用可能性は大である。   As described above, according to the present invention, the whisker growth, which has been a problem when using, for example, a Sn 100% plated lead wire as the external lead wire, is suppressed from the request for Pb-free. Even if this occurs, a highly reliable aluminum electrolytic capacitor that can be safely mounted on a circuit board for a long period of time is provided, and its industrial applicability is great. .

１ コンデンサ素子
２ リード端子
２１ タブ端子
２１ａ 扁平部
２１ｂ 丸棒部
２２ 外部引出リード線
２３ 溶接部
３ 外装ケース
４ 封口ゴム
５ 端子挿通孔
５１ 丸棒嵌合孔
５２ リード線挿通孔
５３ 溶接部収納部 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Lead terminal 21 Tab terminal 21a Flat part 21b Round bar part 22 Outer lead wire 23 Welding part 3 Exterior case 4 Sealing rubber 5 Terminal insertion hole 51 Round bar fitting hole 52 Lead wire insertion hole 53 Welding part accommodating part

Claims (3)

ともにリード端子が取り付けられたアルミニウム材からなる陽極箔と陰極箔とをセパレータを介して巻回してなるコンデンサ素子と、上記コンデンサ素子が所定の電解物質とともに収納される有底筒状の外装ケースと、上記リード端子用の端子挿通孔が穿設されていて上記外装ケースの開口部に装着される封口ゴムとを含み、上記リード端子が、扁平部と丸棒部とを有するアルミニウム材からなるタブ端子と、表面に鉛を含まず錫を含むメッキ層を有し上記丸棒部の端部に溶接された外部引出リード線とを備え、上記リード端子が上記端子挿通孔内に挿通され、上記外部引出リード線が上記外装ケース外に引き出されるアルミニウム電解コンデンサにおいて、
上記封口ゴムの端子挿通孔には、上記タブ端子の丸棒部が嵌合される丸棒嵌合孔と、上記丸棒嵌合孔に連通していて上記外部引出リード線が挿通されるリード線挿通孔とが含まれ、かつ、上記丸棒嵌合孔と上記リード線挿通孔との間に、上記丸棒部と上記外部引出リード線との溶接部が収納される溶接部収納部を備え、
上記メッキ層に含まれている錫に起因する上記溶接部でのウィスカの発生および成長を抑制するとともに上記ウィスカの外部への漏出を防止するため、上記リード線挿通孔の孔径が上記外部引出リード線の直径よりも小径で上記溶接部が外気に晒されないように外部と遮断されているとともに、上記溶接収納部が上記溶接部に密着する漏斗状に形成されており、かつ、上記リード線挿通孔の軸長が０．２ｍｍ以上であることを特徴とするアルミニウム電解コンデンサ。 A capacitor element formed by winding an anode foil and a cathode foil made of an aluminum material each having a lead terminal attached thereto via a separator, and a bottomed cylindrical outer case in which the capacitor element is accommodated together with a predetermined electrolytic substance; A tab made of an aluminum material, wherein the lead terminal has a flat portion and a round bar portion, the terminal insertion hole for the lead terminal being perforated and a sealing rubber attached to the opening of the exterior case Comprising a terminal and an external lead wire having a plated layer containing no tin on the surface and containing tin , welded to the end of the round bar, the lead terminal being inserted into the terminal insertion hole, In the aluminum electrolytic capacitor in which the external lead wire is drawn out of the outer case,
The sealing rubber terminal insertion hole has a round bar fitting hole into which the round bar portion of the tab terminal is fitted, and a lead that communicates with the round bar fitting hole and into which the external lead wire is inserted. A welded portion storage portion that includes a wire insertion hole and that accommodates a welded portion between the round bar portion and the external lead wire between the round bar fitting hole and the lead wire insertion hole. Prepared,
To prevent leakage to the outside of the whiskers is suppressed the occurrence and growth of whiskers at the weld due to the tin contained in the plating layer, upper diameter of the lead wire insertion hole Kigaibu drawer together with the welded portion smaller in diameter than the diameter of the lead wires are isolated from the outside so as not to be exposed to the air, the welding housing section is formed in that leakage DOO shaped to close contact with the welded portion, and the An aluminum electrolytic capacitor, wherein the lead wire insertion hole has an axial length of 0.2 mm or more . 上記リード線挿通孔の孔径が、上記外部引出リード線の直径に対して８０〜９０％であることを特徴とする請求項１に記載のアルミニウム電解コンデンサ。 The aluminum electrolytic capacitor according to claim 1, wherein a hole diameter of the lead wire insertion hole is 80 to 90 % with respect to a diameter of the external lead wire. 上記リード線挿通孔の軸長が、上記封口ゴムの厚さの２０％以上であることを特徴とする請求項１または２に記載のアルミニウム電解コンデンサ。 The aluminum electrolytic capacitor according to claim 1 or 2 , wherein an axial length of the lead wire insertion hole is 20% or more of a thickness of the sealing rubber.
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