JP2010074089A - Electrolytic capacitor, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor that reduces equivalent DC resistance, has a large capacity, and can be miniaturized. <P>SOLUTION: A capacitor element 5 of the electrolytic capacitor includes anode foil 2, cathode foil 3, a sheet member 4, lead tabs 7A, 7B, and a winding stop tape 5. A conductive polymer layer is formed on the surfaces of the anode foil 2 and the cathode foil 3. The sheet member 4 is provided in the anode foil 2 and the cathode foil 3 so that a winding start portion is covered, the anode foil 2, the cathode foil 3 and the sheet member 4 are wound without going through separators, the outermost periphery is stopped by the winding stop tape, thus manufacturing the capacitor element 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wound electrolytic capacitor and a method for manufacturing the same.

Conventional winding electrolytic capacitors shown in FIGS. 7 and 8 are known. (See Patent Document 1)
As shown in the cross-sectional view of FIG. 7, the electrolytic capacitor 1 includes a capacitor element 6 having lead wires 8A and 8B, a bottomed case 9 for housing the capacitor element 6, and a sealing member for sealing the capacitor element 6. 10. The vicinity of the open end of the bottomed case 9 is subjected to lateral drawing and curling.

  As shown in the perspective view of FIG. 8, the capacitor element 6 is formed by being wound through a pair of electrode foils composed of an anode foil 2 and a cathode foil 3 and a separator 12, and being fastened with a winding tape 5. . The anode lead wire 8A is connected to the anode foil 2 via the anode lead tab 7A, and the cathode lead wire 8B is connected to the cathode foil 3 via the cathode lead tab 7B.

  Moreover, as an electrolyte of the electrolytic capacitor 1 having such a structure, an electrolytic solution, a solid electrolyte, or the like is used, and the gap between the electrode foils 2 and 3 of the capacitor element 6 is filled.

Such an electrolytic capacitor 1 has a large electrostatic capacity and is widely used for a decoupling circuit or a power supply circuit of a CPU. However, with the development of electronic devices, it has become necessary to respond to many demands such as large capacity, small size, and low ESR (Equivalent Series Resistance).
Japanese Patent No. 3495529

  In the conventional electrolytic capacitor, in order to prevent a short circuit due to contact between the anode foil and the cathode foil, it was necessary to insert a separator on the entire surface between the anode foil and the cathode foil and to wind it. Therefore, it has been a factor that hinders the reduction of ESR and the increase in capacity and size.

  A first aspect of the present invention is a capacitor in which an anode foil in which a dielectric film and a conductive polymer layer are sequentially formed on the surface, and a cathode foil in which the conductive polymer layer is formed on the surface are wound without using a separator. An electrolytic capacitor including an element, the outer peripheral surface of the winding start portion of the anode foil, the inner peripheral surface of the anode foil winding start portion, the outer peripheral surface of the cathode foil winding start portion, Any one of the inner peripheral surface of the winding start portion of the cathode foil is an electrolytic capacitor covered with a sheet member.

  Furthermore, one end of the anode foil and one end of the cathode foil are used as a winding start portion, and the sheet member extends to the center side of the capacitor element beyond one end of the anode foil and / or one end of the cathode foil. Is preferred.

  Furthermore, the sheet member is preferably made of at least one of natural fiber, synthetic resin, and conductive polymer.

  Furthermore, the gap between the anode foil and the cathode foil is preferably filled with a conductive polymer.

  According to a second aspect of the present invention, there is provided a capacitor element obtained by winding an anode foil having a dielectric film and a conductive polymer layer sequentially formed on a surface thereof, and a cathode foil having a conductive polymer layer formed on the surface without a separator. An electrolytic capacitor manufacturing method comprising: a first step of forming a conductive polymer layer on the surfaces of an anode foil and a cathode foil; an outer peripheral surface of a winding start portion of the anode foil; and winding of the anode foil The sheet member is arranged and wound so as to cover one of the inner peripheral surface of the start portion, the outer peripheral surface of the cathode foil start portion, and the inner peripheral surface of the cathode foil start portion. And a second step of producing a rotating capacitor element.

  Further, in the second step, the sheet member is arranged with the winding start portion as one end portion of the anode foil and one end portion of the cathode foil, only the sheet member extending from the one end is wound, and then the anode foil and the cathode are wound. It is preferable to wind the foil together with the sheet member.

  Thus, according to the present invention, an electrolytic capacitor can be produced without using a separator by previously forming a conductive polymer layer on the surface of the electrode foil. Further, by covering and winding the winding start portion of the electrode foil of the capacitor element with the sheet member, it is possible to prevent damage to the winding start portion of the electrode foil and avoid a short circuit between the anode and the cathode.

  The best mode for carrying out the present invention will be described below.

  FIG. 1 is a front sectional view of the electrolytic capacitor of the present invention, and FIG. 2 is a perspective view of the capacitor element of the electrolytic capacitor of the present invention.

  The electrolytic capacitor 1 of the present invention includes a capacitor element 6, lead tabs 7 </ b> A and 7 </ b> B, lead wires 8 </ b> A and 8 </ b> B, a bottomed case 9, a sealing member 10, and a seat plate 11. The capacitor element 6 includes an anode foil 2 and a cathode foil 3 connected to an anode lead tab 7A and a cathode lead tab 7B, and a sheet member 4.

  First, an oxide film is formed by chemical conversion treatment on at least the surface of the anode foil 2 among the anode foil 2 and the cathode foil 3 made of a valve metal. The chemical conversion treatment was performed by immersing the electrode foil in the chemical conversion solution and applying a voltage.

  Then, conductive polymer layers are formed on the surfaces of the anode foil 2 and the cathode foil 3. The conductive polymer layer preferably contains at least one aliphatic, aromatic, heterocyclic, and heteroatom-containing conductive polymer. Among them, polythiophene, polypyrrole, Polyaniline-based conductive polymers are preferred. Examples of the method of forming the conductive polymer layer include a method of coating the surface of the electrode foil with a conductive polymer solution or a conductive polymer dispersion in which fine particles of a conductive polymer are dispersed.

  Next, lead tabs 7A and 7B are connected to the anode foil 2 and the cathode foil 3 on which the conductive polymer layer is formed, respectively. The lead tabs 7A and 7B are electrically connected to the anode foil 2 and the cathode foil 3, respectively, and a dielectric film is preferably formed on at least the surface of the anode lead tab 7A.

  Subsequently, the anode foil 2 and the cathode foil 3 are wound without using a separator, and the outermost periphery is stopped with a winding tape 5. At this time, since the conductive polymer layer does not cause a short circuit even when the anode foil 2 and the cathode foil 3 are in contact with each other, a separator is formed on the entire surface between the anode foil and the cathode foil as in a conventional electrolytic capacitor. No need to intervene.

  However, when winding using a winder, since the capacitor element does not have a separator, one end of the anode foil 2 and the cathode foil 3 starts to be wound as shown in FIG. As a part, it is inserted into the core 13 of the winder, and is entangled and wound as shown in FIG. In this case, when the anode foil 2 and the cathode foil 3 are in contact with the edge portion A of the winding core, the dielectric film and the conductive polymer layer on the surface are damaged, and the anode and the cathode are easily short-circuited. A method for preventing this will be described below.

  FIG. 4 is a view of the vicinity of the core during winding. As shown in FIG. 4A, when one end of the anode foil 2 and the cathode foil 3 is inserted into the winding core 13 as a winding start portion, at least one sheet member 4 is connected to the anode foil 2 and the cathode foil 3. It is arranged so as to cover the winding start portion. And as shown in FIG.4 (b), when the winding core 13 rotates clockwise, the anode foil 2, the cathode foil 3, and the sheet | seat member 4 will be wound together. Since the winding start portions of the anode foil 2 and the cathode foil 3 of the capacitor element wound in this way are wound together with at least one or more sheet members, the edge portion A of the winding core 13, the anode foil 2 and the cathode Contact with the foil 3 can be prevented.

  The winding start portion may not be the end portions of the anode foil 2 and the cathode foil 3. FIG. 5 is a view of the vicinity of the core 13 when two anode foils and one cathode foil are used and the central portion in the longitudinal direction of the cathode foil 3 is a winding start portion. As shown in FIG. 5A, the sheet member 4 is disposed so as to cover the central portion in the longitudinal direction of the cathode foil 3 and is inserted into the core 13. The anode foil 2 is disposed on both sides of the cathode foil 3, and one anode foil 2 is disposed on one side of the core 13 and the other anode foil 2 is disposed on the opposite side of the core 13. When the winding core 13 rotates in the clockwise direction, the anode foil 2, the cathode foil 3, and the sheet member 4 are wound as shown in FIG. Thereby, contact between the edge portion of the core 13 and the anode foil 2 and the cathode foil 3 can be prevented. Thus, the winding start portion of the electrode foil may be not only the end portion of the electrode foil but also the central portion in the longitudinal direction.

  Further, the anode foil 2 and the cathode foil 3 may not be inserted into the winding core 13 and only the sheet member may be inserted and wound. FIG. 6 is a view when only the sheet member 4 is inserted into the winding core 13 for winding. As shown in FIG. 6A, the sheet member 4 is arranged so as to cover the winding start portion at one end of the anode foil 2 and the cathode foil 3, but a part of the sheet member 4 is the anode foil 2. The cathode foil 3 extends from one end to the core side, that is, the center side of the capacitor element, and is inserted into the core 13. When the winding core 13 rotates in the clockwise direction, as shown in FIG. 6B, the sheet member 4 is wound and the anode foil 2 and the cathode foil 3 are wound and wound. In this case, only the sheet member 4 is inserted into the winding core 13, and the anode foil 2 and the cathode foil 3 are not inserted into the winding core 13, thereby preventing contact with the edge portion A of the winding core 13. be able to.

  The number of the sheet members 4 to be used may be at least one or more, and can be appropriately changed according to the contact location between the electrode foil and the edge portion of the core, the number of the electrode foil, and the like.

  Moreover, you may affix the said sheet | seat member 4 to the winding start part of the anode foil 2 and the cathode foil 3 using an adhesive before winding. As the pressure-sensitive adhesive, a general pressure-sensitive adhesive may be used, and examples thereof include acrylic, silicone and rubber adhesives.

  The sheet member 4 only needs to be strong enough to protect and wind the anode foil 2 and the cathode foil 3, and may or may not have ion permeability unlike a conventionally used separator. Materials include, for example, natural fibers such as Manila hemp, esparto, craft, and wood pulp, synthetic resins such as nylon, acrylic, vinylon, aramid, and Teflon (registered trademark), polythiophene, polypyrrole, polyaniline, and other highly conductive materials. A molecule | numerator etc. are mentioned as a material.

  Next, the capacitor element 6 is cut and an oxide film is formed on the end faces of the anode foil 2 and the cathode foil 3. Cut formation is performed by immersing the capacitor element in a chemical conversion solution and applying a voltage.

  Subsequently, a conductive polymer layer is formed in the gap between the anode foil 2 and the cathode foil 3 of the capacitor element 6 by electrolytic polymerization or chemical polymerization. The conductive polymer preferably contains at least one aliphatic, aromatic, heterocyclic, and heteroatom-containing conductive polymer, and among them, polythiophene, polypyrrole, polyaniline. A conductive polymer is preferable. Further, instead of the conductive polymer, an electrolytic solution can be impregnated into the capacitor element 6 and used.

  Thereafter, the capacitor element 6 is accommodated in the bottomed case 9, and the sealing member 10 is inserted into the opening end of the bottomed case 9 to perform lateral drawing and curling. Then, the seat plate 11 is inserted into the curled surface, and the lead wires 8A and 8B are pressed and bent as electrode terminals to complete the electrolytic capacitor 1.

Thus, according to the present invention, an electrolytic capacitor can be produced without using a separator by previously forming a conductive polymer layer on the surface of the electrode foil. Furthermore, by inserting a sheet member into the winding start portion of the electrode foil of the capacitor element and winding it together, the electrode foil is prevented from being damaged due to contact with the edge portion of the winding core of the winder, and between the anode and the cathode. A short circuit can be avoided.
[Example 1]
First, etching treatment was performed on the surfaces of the anode foil 2 and the cathode foil 3 made of aluminum. Then, the oxide foil was formed by immersing the anode foil 2 subjected to the etching treatment in a chemical conversion solution and applying a voltage.

  Subsequently, a conductive polymer layer made of a polythiophene-based conductive polymer was formed on the surfaces of the anode foil 2 and the cathode foil 3.

  Next, an anode lead tab 7A and a cathode lead tab 7B were connected to the anode foil 2 and the cathode foil 3, respectively.

  Then, as shown in FIG. 4 (a), a sheet member 4 made of Manila hemp is arranged at a position covering the winding start portion at one end of the anode foil 2 and the cathode foil 3, as shown in FIG. 4 (b). Then, the winding core 13 was rotated in the clockwise direction, and the anode foil 2, the cathode foil 3, and the sheet member 4 were wound together. After winding, the outermost periphery was stopped with a winding tape 5 to produce a capacitor element 6.

  Subsequently, cut formation of the capacitor element 6 was performed. Cut formation was performed by immersing the capacitor element 6 in a chemical conversion solution and applying a voltage.

  Then, the capacitor element was impregnated with 3,4-ethylenedioxythiophene, which becomes a conductive polymer by polymerization, and p-toluenesulfonic acid ferric alcohol solution as an oxidizing agent solution. The capacitor element 6 was thermochemically polymerized by applying heat to form a conductive polymer layer between the anode foil 2 and the cathode foil 3.

Thereafter, the capacitor element 6 was housed in a bottomed case 9 and a sealing member 10 was inserted into the open end of the bottomed case 9 to perform lateral drawing and curling. Then, the seat plate 11 was inserted into the curled surface, and the lead wires 8A and 8B were pressed and bent to complete the electrolytic capacitor 1.
[Example 2]
An electrolytic capacitor was produced in the same manner as in Example 1 except that aramid fiber was used as the material of the sheet member 4.
[Example 3]
An electrolytic capacitor was produced in the same manner as in Example 1 except that a fluororesin was used as the material of the sheet member 4.
[Example 4]
An electrolytic capacitor was produced in the same manner as in Example 1 except that a polythiophene conductive polymer was used as the material of the sheet member 4.
[Example 5]
In Example 5, the winding method is different from Example 1, and as shown in FIG. 6A, the sheet member 4 made of Manila hemp is arranged so as to cover the winding start portions of the anode foil 2 and the cathode foil 3, Part of the sheet member 4 extends in the direction of the core from the ends of the winding start portions of the anode foil 2 and the cathode foil 3, and after the extended portion of the sheet member is inserted into the core 13, FIG. As shown in b), the core 13 was rotated clockwise to wind the sheet member 4, and one end of the anode foil 2 and the cathode foil 3 was wound around the sheet member 4. Except for this, an electrolytic capacitor was fabricated in the same manner as in Example 1.
[Example 6]
An electrolytic capacitor was produced in the same manner as in Example 5 except that aramid fiber was used as the material of the sheet member 4.
[Example 7]
An electrolytic capacitor was produced in the same manner as in Example 5 except that a fluororesin was used as the material of the sheet member 4.
[Comparative example]
An electrolytic capacitor was produced in the same manner as in Example 1 except that the sheet member 4 was omitted and wound.
[Conventional example]
In the conventional example, except that the anode foil 2 and the cathode foil 3 on which the conductive polymer layer is not formed are used, the sheet member 4 is omitted, and the capacitor element is produced by winding with the separator paper made of Manila hemp. In the same manner as in Example 1, an electrolytic capacitor was produced.

  Table 1 shows the electrical characteristic measurement results of 30 average values for each of the electrolytic capacitors of Examples 1 to 7, Comparative Example, and Example. The electrolytic capacitor has a rated voltage of 4 V and a capacity of 560 μF, and has dimensions of 8 mm in diameter and 12 mm in height. Further, the capacitance and tan δ were measured at a frequency of 120 kHz, and the equivalent DC resistance was measured at a frequency of 100 kHz. The leakage current is a value two minutes after the rated voltage is applied.

  From the results of Table 1, the electrolytic capacitors according to Examples 1 to 7 and the comparative example have lower equivalent DC resistance than the electrolytic capacitors of the conventional examples. Therefore, an electrolytic capacitor having a low equivalent DC resistance can be produced by forming a conductive polymer on the surfaces of the anode foil and the cathode foil and omitting the separator.

  Furthermore, the electrolytic capacitors according to Examples 1 to 7 have lower leakage current than the electrolytic capacitors of the comparative examples. Therefore, in an electrolytic capacitor in which a conductive polymer layer is formed on the surfaces of the anode foil and the cathode foil and the separator is omitted, the sheet member is arranged so that the winding start portion of the anode foil and the cathode foil contacts with the edge portion of the core. By preventing this, an increase in leakage current can be suppressed.

  Moreover, since the electrolytic capacitors according to Examples 1 to 7 and the comparative example do not use a separator, the diameter can be made smaller than the electrolytic capacitor according to the conventional example. That is, the electrolytic capacitor can be reduced in size.

  Moreover, since the electrolytic capacitors according to Examples 1 to 7 and the comparative example do not use a separator, the electrolytic capacitors have a capacity 1.6 times that of the conventional electrolytic capacitors having the same diameter. That is, the capacity of the electrolytic capacitor can be increased.

  The above embodiments are merely illustrative of the present invention and should not be construed as limiting the invention described in the claims. The present invention can be freely modified within the scope of the claims and the scope of equivalent meanings.

It is sectional drawing of the electrolytic capacitor of this invention. It is a perspective view of the capacitor | condenser element used for the electrolytic capacitor of this invention. In this invention, it is a figure of the core vicinity at the time of winding, without inserting a sheet | seat member in the winding start part of electrode foil. In this invention, it is a figure of the core vicinity at the time of inserting and winding a sheet | seat member in the winding start part of electrode foil. In this invention, it is a figure of the core vicinity at the time of making the center part of electrode foil into a winding start part, and inserting and winding a sheet | seat member in this winding start part. In this invention, while winding up a sheet | seat member, it is a figure of the core vicinity at the time of winding up the winding start part of electrode foil around a sheet | seat member. It is sectional drawing of the conventional electrolytic capacitor. It is a perspective view of the capacitor | condenser element used for the conventional electrolytic capacitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolytic capacitor 2 Anode foil 3 Cathode foil 4 Sheet member 5 Winding tape 6 Capacitor element 7 Lead tab 8 Lead wire 9 Bottomed case 10 Sealing member 11 Seat plate 12 Separator 13 Core 14 Edge part

Claims (6)

An anode foil in which a dielectric film and a conductive polymer layer are sequentially formed on the surface;
A cathode foil having a conductive polymer layer formed on the surface;
An electrolytic capacitor comprising a capacitor element wound without a separator,
The outer peripheral surface of the winding start portion of the anode foil, the inner peripheral surface of the winding start portion of the anode foil, the outer peripheral surface of the cathode foil winding start portion, and the winding start portion of the cathode foil An electrolytic capacitor in which one of the inner peripheral surface and the surface is covered with a sheet member. 2. The sheet according to claim 1, wherein one end of the anode foil and one end of the cathode foil serve as a winding start portion, and the sheet member extends beyond one end of the anode foil and / or one end of the cathode foil. Electrolytic capacitor. The electrolytic capacitor according to claim 1, wherein the sheet member is made of at least one of natural fiber, synthetic resin, and conductive polymer. The electrolytic capacitor according to claim 1, wherein a gap between the anode foil and the cathode foil is filled with a conductive polymer. An anode foil in which a dielectric film and a conductive polymer layer are sequentially formed on the surface;
A cathode foil having a conductive polymer layer formed on the surface;
Is a method of manufacturing an electrolytic capacitor including a capacitor element wound without using a separator,
A first step of forming a conductive polymer layer on the surfaces of the anode foil and the cathode foil;
The outer peripheral surface of the winding start portion of the anode foil, the inner peripheral surface of the winding start portion of the anode foil, the outer peripheral surface of the cathode foil winding start portion, and the winding start portion of the cathode foil A second step of producing a capacitor element by arranging and winding a sheet member so as to cover either of the inner peripheral surface of
An electrolytic capacitor manufacturing method comprising: In the second step, the sheet member is disposed with the winding start portion as one end of the anode foil and one end of the cathode foil, and only the sheet member extending from the one end is wound, The method for manufacturing an electrolytic capacitor according to claim 5, wherein the anode foil and the cathode foil are wound together with the sheet member.