JP2004119828A - Electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the high-frequency characteristics of an electrolytic capacitor having improved impedance and ESL characteristics at a high frequency. <P>SOLUTION: The electrode leads having a round rods are connected to a positive electrode foil 2 and a cathode electrode foil 3 respectively and wound with a separator 4 in between to form a capacitor element 1, and the capacitor element 1 is inserted with electrolyte or after impregnation of electrolyte into a case 9 having a bottom. In the electrolytic capacitor with an opening of the case 9 sealed with a sealing member, the rod of each electrode lead has each flat face at the opposite parts, so the impedance and ESL characteristics at the high frequency can be improved. <P>COPYRIGHT: (C)2004,JPO

Description

【００１２】
上記の表１から明らかなように、本発明による電極引出リードの丸棒部に電極板を接続した実施例１〜４は、電極板を接続していない従来例よりインピーダンス、ＥＳＬ共に著しく優れた効果が得られる。電極板間隔が狭くなるにつれてインピーダンス、ＥＳＬが改善されている。
【００１３】
次にＤ形電極板の形状について検討した。Ｄ形電極板を、上記実施例３の半楕円形、φ７ｍｍとした半円形、平面部長さ６ｍｍ幅４ｍｍとした半楕円形、７ｍｍ×４ｍｍの角柱形とした各電解コンデンサを作製し、静電容量と４ＭＨｚＥＳＬを測定後、１０５℃定格印加２０００時間の高温負荷試験を実施した。初期ＥＳＬ値は、平面部６ｍｍの半楕円形が劣り、その他はほぼ同等であった。高温負荷試験の結果、静電容量の変化率は角形が最も悪く、次に半円形が悪かった。原因は特定できなかったが、封口ゴムと電極板との嵌合性の影響と推測される。
上記結果より、少なくとも電極引出リードの対向する面に平面部を設ければ低ＥＳＬ化の効果が得られ、半円形、半楕円形、角形、直線と曲線の組合せからなる形状等でもよい。なお、長期信頼性を必要とする用途には、封口部材との嵌合性から、電極板の平面部の長さが電極板の幅の２倍を超えた半楕円形や半トラック形等のＤ形電極板が望ましい。
【００１４】
その他の実施例として、電極板間隔を０．５ｍｍとし、図３および図４に示す絶縁性ゴムからなるスペーサをコンデンサ素子上面と電極板および電極板間に設けた電解コンデンサを作製し、４ＭＨｚＥＳＬを測定後、１０５℃定格印加試験を実施した。４ＭＨｚＥＳＬは実施例３より２０％改善し、１０５℃定格印加試験後もＥＳＬの増加を抑えることが可能であった。また、電解コンデンサの組立速度を速くしても実施例３よりショート等の組立不良の発生率を低く抑えることができた。
【００１５】
実施例では、電解質に水を主溶媒とした駆動用電解液を用いたが、本発明はこれに限定されるものではなく、エチレングリコールやγ−ブチロラクトンを主溶媒とする公知の電解液を用いても同等の効果があり、また、電解質にポリピロールやポリエチレンジオキシエチレン等の固体電解質を用いても同等の効果があることは言うまでもない。
【００１６】
そして、その他の実施例では、コンデンサ素子上面と電極板および電極板間に絶縁性ゴムからなるスペーサを設けたが、スペーサは絶縁物であればよく、絶縁性樹脂板や、電極板の下面および対向する平面部に絶縁性樹脂を塗布しても同等の効果がある。また、コンデンサ素子上面と電極板との間に絶縁性樹脂板、電極板間を封口部材の突起物で絶縁してもよい。
【００１７】
さらに、電極引出リードの材質は、公知の材料を必要により適宜選択組み合わせればよい。
【００１８】
【発明の効果】
以上説明したように本発明による電極引出リードの丸棒部の対向する面が平面となるＤ形電極板を有する電解コンデンサは、高周波でのインピーダンスとＥＳＬ特性を改善することができる。さらに、コンデンサ素子上面と電極板および電極板間に絶縁性スペーサを設けることで、平面部を平行に配置しやすくなるので、一層の低ＥＳＬ化が可能となるとともに、スペーサにより絶縁が保たれるので、ショートを防止しながら製品の小形化が可能となる。また、４端子形とすることなく低インピーダンス、低ＥＳＬ化が図れるので、基板は４端子を接続するための専用設計が不要となり、端子数を減らすことができるので配線の高密度化も可能となる。
【図面の簡単な説明】
【図１】本発明の実施例による電解コンデンサ素子の概要図である。
【図２】本発明の実施例による電解コンデンサの断面図である。
【図３】本発明の他の実施例によるコンデンサ素子の概要図である。
【図４】本発明の他の実施例による電解コンデンサの断面図である。
【図５】従来の電解コンデンサ素子の概要図である。
【図６】従来の電解コンデンサの断面図である。
【符号の説明】
１　コンデンサ素子
２　陽極箔
３　陰極箔
４　セパレータ
５　リード線
６，６ａ　丸棒部
７　電極板
８　アルミケース
９　封口部材
１０　電極板間隔
１１　絶縁性スペーサ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrolytic capacitor, and more particularly to improvement of high frequency characteristics of an electrolytic capacitor.
[0002]
[Prior art]
As shown in FIGS. 5 and 6, a conventional electrolytic capacitor is obtained by impregnating an electrolytic solution into a capacitor element 1 in which an anode foil 2 and a cathode foil 3 which have been subjected to an etching process and an oxide film forming process are wound via a separator 4. It was housed in a metal case, and the opening was sealed with a sealing member. In recent years, with high performance of personal computers and the like, electrolytic capacitors have also been required to have low impedance at high frequencies even at high frequencies, and a technology has been proposed in which connection terminals are connected to both ends of an anode foil and a cathode foil to form a four-terminal type. (For example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-50-110064 (page 2-3, FIG. 1-3)
[0004]
[Problems to be solved by the invention]
The four-terminal type can reduce the impedance, but requires higher assembly accuracy than the two-terminal type, which lowers productivity and requires a special design of the board on which the electrolytic capacitor is mounted. Was. Furthermore, the operating frequency of switching power supplies and microprocessors has become higher, and not only the impedance but also the equivalent series inductance (ESL) must be reduced. There has been a demand for an electrolytic capacitor capable of reducing impedance and ESL without changing the design.
[0005]
[Means for Solving the Problems]
The present invention solves the above-mentioned problem, and connects a flat portion to be connected to an electrode foil and an electrode extraction lead composed of a round bar portion connected to a flat portion by welding a lead wire to the anode foil and the cathode foil, respectively, and a separator. Into a capacitor element by winding the capacitor element after impregnating the electrolyte with the electrolyte or with the electrolyte into a bottomed case, and sealing the opening of the case with a sealing member.
The electrolytic capacitor is characterized in that a round bar portion of each electrode lead has a flat surface at the opposing portion.
[0006]
An electrolytic capacitor characterized in that a plane of the round bar portion is constituted by a D-shaped electrode plate.
[0007]
An electrolytic capacitor, wherein an insulating spacer is provided between the electrode plates.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
As shown in FIG. 1 and FIG. 2, the electrode lead of the electrolytic capacitor according to the present invention has a flat surface at the portion of the round bar portion 6 where the anode electrode lead and the cathode electrode lead are opposed. The flat portion of the round bar 6 was formed by connecting the D-shaped electrode plate 7 to the round bar 6. The electrode lead is connected to each of the anode foil 2 and the cathode foil 3 and wound around the separator 4 to form the capacitor element 1. After forming the capacitor element, the D-shaped electrode plate 7 is crimped to the round bar portion of the electrode lead and connected by a method such as welding, and the capacitor element 1 is impregnated with a driving electrolyte and / or a conductive polymer as an electrolyte. Afterwards, or after being inserted into the bottomed capacitor case 8 together with the electrolyte, the opening of the case 8 is sealed with a sealing member 9 such as a sealing rubber or epoxy resin inserted through the electrode lead-out lead to obtain an electrolytic capacitor. The electrode plate 7 and the round bar 6 are made of aluminum or aluminum alloy, and the lead wire 5 is made of iron, iron alloy, copper or copper alloy as a core material, and is plated with nickel, tin, silver, gold or the like. .
[0009]
【Example】
A semi-elliptical (D-type) electrode plate having a plane length of 7 mm, a width orthogonal to the plane of 3 mm, and a thickness of 2.5 mm is connected to the round bar portion of the electrode lead, rated at 6.3 V / 3300 μF, size φ10 × 25 mmL Then, ten aluminum electrolytic capacitors each having the distance between the electrode plates set as shown in Table 1 were produced. The electrode lead was positioned such that the lead wire of the electrode lead was located at １ ／ and ／ of the case diameter. The electrode lead is made of aluminum for the electrode plate and round bar, the lead wire is made of copper and tin plated on the surface, the main solvent is water, the secondary solvent is ethylene glycol, and the main solute is used. Adipic acid was used.
[0010]
The 100 kHz impedance and 4 MHz ESL of each electrolytic capacitor were measured, and the results shown in Table 1 were obtained.
[0011]
[Table 1]

[0012]
As is clear from Table 1 above, Examples 1 to 4 in which an electrode plate was connected to the round bar portion of the electrode lead according to the present invention were significantly superior in both impedance and ESL to the conventional example in which no electrode plate was connected. The effect is obtained. As the distance between the electrode plates becomes smaller, the impedance and ESL are improved.
[0013]
Next, the shape of the D-shaped electrode plate was examined. Electrolytic capacitors were manufactured by forming the D-shaped electrode plate in the semi-elliptical shape of Example 3 described above, a semi-circular shape having a diameter of 7 mm, a semi-elliptical shape having a plane length of 6 mm and a width of 4 mm, and a prism having a size of 7 mm × 4 mm. After measuring the capacity and the 4 MHz ESL, a high-temperature load test was performed at a rated application of 105 ° C. for 2000 hours. The initial ESL value was inferior in the semi-elliptical shape of the plane portion of 6 mm, and almost the same in the others. As a result of the high-temperature load test, the change rate of the capacitance was the worst for the square shape, and then worse for the semicircle. Although the cause could not be specified, it is presumed to be due to the effect of the fitting property between the sealing rubber and the electrode plate.
According to the above results, the effect of reducing the ESL can be obtained if at least a flat portion is provided on the surface facing the electrode lead, and a semicircular shape, a semielliptical shape, a square shape, a shape composed of a combination of a straight line and a curve, or the like may be used. In applications requiring long-term reliability, the length of the flat portion of the electrode plate is more than twice the width of the electrode plate, such as a semi-elliptical shape or a semi-track shape, due to the fitting property with the sealing member. D-shaped electrode plates are desirable.
[0014]
As another embodiment, an electrolytic capacitor having an electrode plate interval of 0.5 mm, a spacer made of insulating rubber shown in FIGS. 3 and 4 provided between the upper surface of the capacitor element, the electrode plate, and the electrode plate is manufactured. After the measurement, a 105 ° C. rated application test was performed. The 4 MHz ESL was improved by 20% from that of Example 3, and it was possible to suppress the increase in ESL even after the rated application test at 105 ° C. Further, even when the assembly speed of the electrolytic capacitor was increased, the occurrence rate of assembly failure such as a short circuit could be suppressed lower than that of the third embodiment.
[0015]
In the examples, a driving electrolyte using water as a main solvent was used as an electrolyte, but the present invention is not limited to this, and a known electrolyte using ethylene glycol or γ-butyrolactone as a main solvent was used. It is needless to say that the same effect can be obtained even when a solid electrolyte such as polypyrrole or polyethylenedioxyethylene is used as the electrolyte.
[0016]
In the other embodiments, the spacer made of insulating rubber is provided between the upper surface of the capacitor element and the electrode plate and the electrode plate. However, the spacer may be any insulating material, such as an insulating resin plate, the lower surface of the electrode plate, and the like. The same effect can be obtained by applying an insulating resin to the opposing flat surface. Further, an insulating resin plate may be provided between the upper surface of the capacitor element and the electrode plate, and the electrode plate may be insulated by a projection of the sealing member.
[0017]
Further, as the material of the electrode lead, a known material may be appropriately selected and combined as needed.
[0018]
【The invention's effect】
As described above, the electrolytic capacitor having the D-shaped electrode plate in which the opposite surface of the round bar portion of the electrode lead according to the present invention has a flat surface can improve the high-frequency impedance and ESL characteristics. Further, by providing an insulating spacer between the upper surface of the capacitor element and the electrode plate and the electrode plate, it is easy to arrange the plane portions in parallel, so that the ESL can be further reduced and insulation is maintained by the spacer. Therefore, the size of the product can be reduced while preventing a short circuit. In addition, since low impedance and low ESL can be achieved without using a four-terminal type, a dedicated design for connecting the four terminals is not required on the substrate, and the number of terminals can be reduced, so that the wiring density can be increased. Become.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an electrolytic capacitor element according to an embodiment of the present invention.
FIG. 2 is a sectional view of an electrolytic capacitor according to an embodiment of the present invention.
FIG. 3 is a schematic view of a capacitor element according to another embodiment of the present invention.
FIG. 4 is a sectional view of an electrolytic capacitor according to another embodiment of the present invention.
FIG. 5 is a schematic view of a conventional electrolytic capacitor element.
FIG. 6 is a sectional view of a conventional electrolytic capacitor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode foil 3 Cathode foil 4 Separator 5 Lead wire 6, 6a Round bar part 7 Electrode plate 8 Aluminum case 9 Sealing member 10 Electrode plate interval 11 Insulating spacer

Claims (3)

The electrode lead connected to the flat portion connected to the electrode foil and the lead wire formed by welding a lead wire and connected to the flat portion is connected to the anode foil and the cathode foil, respectively, and wound via a separator to form a capacitor element. In an electrolytic capacitor in which the element is impregnated with an electrolyte or inserted together with the electrolyte into a bottomed case, and the opening of the case is sealed with a sealing member,
An electrolytic capacitor, characterized in that a round bar portion of each electrode lead has a flat surface at an opposing portion. 2. The electrolytic capacitor according to claim 1, wherein a plane of said round bar portion is constituted by a D-shaped electrode plate. 2. The electrolytic capacitor according to claim 1, wherein an insulating spacer is provided between said electrode plates.

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