JP2011009360A - Laminated electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated electrolytic capacitor capable of suitably supplying an electrolyte to a part of an anode foil where a film needs to be formed.SOLUTION: The laminated electrolytic capacitor 1 includes an electrode laminate 2 having an anode foil 4 and a cathode foil 5 laminated alternately with a separator 6A, 6B interposed, and an anode lead 15 and a cathode lead 16. The anode lead 15 is bent zigzag to be connected to a surface (upper surface) of a lead-out part 10 of each anode foil 4. The cathode lead 16 is bent zigzag to be connected to a surface (upper surface) of a lead-out part 12 of each cathode foil 5. The separator 6A has a connection coating part 14 which covers the entire surface of the lead-out part 10 including a connection fixation part of the lead-out part 10 and anode lead 15 when the electrode laminate 2 is formed.

Description

  The present invention relates to a multilayer electrolytic capacitor having a structure in which an anode foil and a cathode foil are alternately laminated via a separator.

  As a conventional multilayer electrolytic capacitor, for example, one described in Patent Document 1 is known. In the multilayer electrolytic capacitor described in Patent Document 1, the anode foil and the cathode foil are alternately laminated with the capacitor paper interposed therebetween, and the lead for the anode is provided on the lead-out tab provided on each of the anode foil and the cathode foil. The cathode lead is joined by laser welding or the like.

JP-A-6-275476

  By the way, in the multilayer electrolytic capacitor as in the prior art, in order to securely connect a plurality of electrode foils to the leads, the leads may be connected and fixed to the surface of the lead portion of each electrode foil. The surface of the anode foil has a structure in which an extremely thin oxide film is formed in an enlarged state. For this reason, when the lead is connected and fixed to the surface of the lead portion of each anode foil, the oxide film of the anode foil is destroyed. Therefore, after the leads are connected to the respective anode foils, film formation using the electrolytic solution is performed in the aging process. Therefore, it is necessary to supply a sufficient amount of electrolytic solution to the portion of the anode foil that requires film formation. . Here, it is conceivable that a large amount of electrolyte is filled in the sealing body (case), but in this case, there is a high possibility of liquid leakage from the sealing body.

  An object of the present invention is to provide a multilayer electrolytic capacitor capable of appropriately supplying an electrolytic solution to a portion of the anode foil that requires film formation.

  The present invention provides an electrode laminate in which anode foil and cathode foil are alternately laminated via a separator, an anode lead connected to the anode foil, a cathode lead connected to the cathode foil, and an electrode laminate. A multilayer electrolytic capacitor having a case for accommodating together with an electrolytic solution, wherein an anode foil and a cathode foil are drawn from the main electrode portion opposed to each other via a separator, an anode lead and a cathode lead, The anode lead is connected and fixed to the surface of the anode foil lead portion, and the separator covers the connection fixing portion between the anode foil lead portion and the anode lead. It is characterized by having.

  Thus, in the multilayer electrolytic capacitor having a structure in which the anode foil and the cathode foil are alternately laminated via the separator, the separator has a function of impregnating and holding the electrolytic solution. Therefore, by providing the separator with a connection covering portion that covers the connection fixing portion between the anode foil lead portion and the anode lead, the connection covering portion retains the electrolytic solution. The electrolyte is sufficiently supplied to the connection fixing portion with the anode lead. As a result, the electrolytic solution can be appropriately supplied to the portion where the film formation of the anode foil is required, that is, the portion where the oxide film is destroyed when the anode lead is connected and fixed to the surface of the lead portion of the anode foil.

  Preferably, the connection covering portion covers the entire surface of the lead portion of the anode foil. For example, when the anode foil is formed by punching, there is no oxide film layer on the cut surface of the lead portion of the anode foil, and therefore it is necessary to form an oxide film layer on the cut surface. Therefore, by making the connection coating portion of the separator cover the entire surface of the lead portion of the anode foil, the electrolyte impregnated in the separator is supplied to the cut surface of the lead portion. Thereby, electrolyte solution can be more appropriately supplied to the part which needs the film formation of anode foil.

  According to the present invention, the electrolytic solution can be appropriately supplied to a portion of the anode foil that requires film formation. As a result, it is possible to sufficiently repair the portion of the surface of the lead-out portion of the anode foil where the oxide film has been destroyed and reduce the leakage current due to aging.

1 is a schematic perspective view showing an appearance of an embodiment of a multilayer electrolytic capacitor according to the present invention. It is a schematic perspective view which shows the electrode laminated body and lead | read | reed which were shown in FIG. FIG. 3 is an exploded perspective view showing an electrode laminate and a lead shown in FIG. 2. It is a figure which shows the cross-sectional structure of the anode foil shown in FIG. It is a top view which shows the arrangement | positioning relationship of the anode foil shown in FIG. 2, a separator, and an anode lead. It is a figure which shows the manufacturing process of the multilayer electrolytic capacitor shown in FIG. It is a figure which shows the manufacturing process of the multilayer electrolytic capacitor shown in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a multilayer electrolytic capacitor according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic perspective view showing an appearance of an embodiment of a multilayer electrolytic capacitor according to the present invention, and FIG. 2 is a schematic perspective view showing a main part of the multilayer electrolytic capacitor shown in FIG. In each of the drawings, the multilayer electrolytic capacitor 1 of the present embodiment includes an electrode laminate 2 and a case 3 that accommodates the electrode laminate 2 together with an electrolytic solution (not shown).

  As shown in FIGS. 2 and 3, the electrode laminate 2 includes a plurality of anode foils 4 and cathode foils 5 that are electrode foils, and separators 6A and 6B. The electrode laminate 2 is configured by alternately laminating anode foils 4 and cathode foils 5 via separators 6A and 6B. Specifically, the electrode laminate 2 is laminated in the order of the separator 6A, the anode foil 4, the separator 6B, the cathode foil 5, the separator 6A,.

  The anode foil 4 is made of a foil-like valve metal. Here, an aluminum foil (for example, a thickness of 50 to 150 μm) is used as the anode foil 4. As shown in FIG. 4, the anode foil 4 has an etching layer 7 formed by an etching process and an oxide film layer 8 formed on the etching layer 7. The cathode foil 5 is made of a metal etching foil in which an etching layer is formed on a metal plain foil. Here, an aluminum etching foil (for example, a thickness of 10 to 100 μm) is used as the cathode foil 5.

  The anode foil 4 has a substantially rectangular main electrode part 9 and a substantially rectangular lead part 10 drawn from the main electrode part 9. The main electrode portion 9 and the lead portion 10 are integrally formed. The cathode foil 5 has a substantially rectangular main electrode part 11 and a substantially rectangular lead part 12 drawn from the main electrode part 11. The main electrode portion 11 and the lead portion 12 are integrally formed. The main electrode portions 9 and 11 are opposed to each other via the separators 6A and 6B.

  Separator 6A, 6B consists of insulating paper, a fiber nonwoven fabric, etc. The separators 6A and 6B have a function of electrically insulating the anode foil 4 and the cathode foil 5 and impregnating and holding an electrolytic solution (not shown).

  The separator 6B has a substantially rectangular shape. The separator 6A includes a main body portion 13 having the same structure as that of the separator 6B, and a substantially rectangular connection covering portion 14 protruding from the main body portion 13. The main body portion 13 has a size larger than that of the main electrode portion 9 of the anode foil 4 (see FIG. 5). The connection covering portion 14 is integrated with the main body portion 13 at a position corresponding to the lead portion 10 of the anode foil 4 and has a size larger than that of the lead portion 10 (see FIG. 5).

  The case 3 is made of a flexible film (for example, a composite packaging film). The case 3 can be produced, for example, by superposing films having a rectangular shape and heat-sealing (heat-sealing) edges of the superposed films. The electrode laminate 2 and the electrolyte (not shown) are accommodated in the case 3 (a space formed by a partial region of the film that is not heat-sealed).

  The multilayer electrolytic capacitor 1 further includes an anode lead 15 connected to each anode foil 4 and a cathode lead 16 connected to each cathode foil 5. These leads 15 and 16 are made of metal plane foil. Here, aluminum foil is used for the leads 15 and 16.

  The anode lead 15 has a zigzag folded shape that is bent so as to be connected to the surface (upper surface) of the lead portion 10 of each anode foil 4. The anode lead 15 is fixed to the surface of the lead portion 10 by caulking and joining (for example, a stitch method or the like) while being in contact with the surface of the lead portion 10 of each anode foil 4. As a result, the anode lead 15 and the lead portion 10 are electrically and physically connected. The anode lead 15 and the lead portion 10 may be fixed by a cold weld method or the like in addition to caulking.

  The cathode lead 16 has a zigzag shape that is bent so as to be connected to the surface (upper surface) of the lead portion 12 of each cathode foil 5. The cathode lead 16 is fixed to the surface of the lead portion 12 by caulking while being in contact with the surface of the lead portion 12 of each cathode foil 5. Thereby, the cathode lead 16 and the lead portion 12 are electrically and physically connected. The cathode lead 16 and the lead portion 12 may be fixed by a cold weld method or the like in addition to caulking.

  When the electrode laminate 2 is formed, the connection covering portion 14 of the separator 6A is formed on the entire surface of the lead portion 10 including the connection fixing portion between the lead portion 10 and the anode lead 15, as shown in FIG. To cover. Therefore, the anode lead 15 is sandwiched between the connection covering portion 14 and the lead portion 10. At this time, in the layers other than the uppermost connection covering portion 14 and the lead-out portion 10, the anode lead 15 is folded between the connection covering portion 14 and the lead-out portion 10.

  Next, a method for manufacturing the multilayer electrolytic capacitor 1 will be described. First, as shown in FIG. 6, an anode foil base material 17 to be the anode foil 4 is prepared. The anode foil base material 17 is made of a large aluminum foil. An etching layer and an oxide film layer are formed in advance on both surfaces of the anode foil base material 17 by etching and anodizing treatment (chemical conversion treatment). Subsequently, a plurality of anode foils 4 are formed by punching the anode foil base material 17 with a mold.

  Also, a cathode foil base material (not shown) to be the cathode foil 5 is prepared. The cathode foil base material is made of a large-sized aluminum etching foil. Then, similarly to the formation of the anode foil 4, a plurality of cathode foils 5 are formed by punching the cathode foil base material with a mold.

  Next, the anode foil 4 and the anode lead 15 are connected by caulking and the cathode foil 5 and the cathode lead 16 are connected. Specifically, as shown in FIG. 7A, the anode lead 15 is brought into contact with the surface of the lead-out portion 10 of the anode foil 4 and the anode lead 15 and the lead-out portion 10 are caulked to thereby form the anode lead 15. And the drawer part 10 are joined. Further, as shown in FIG. 7B, the cathode lead 16 is brought into contact with the surface of the lead portion 12 of the cathode foil 5 and the cathode lead 16 and the lead portion 12 are caulked to thereby form the cathode lead 16 and the lead portion. 12 is joined. Thereby, each anode foil 4 is connected in parallel to the anode lead 15, and each cathode foil 5 is connected in parallel to the cathode lead 16.

  Next, two types of separators 6A and 6B are prepared. Subsequently, as shown in FIGS. 2 and 3, the anode foil 4 and the cathode foil 5 are alternately laminated so that the main electrode portions 9 and 11 face each other with the separators 6A and 6B interposed therebetween. Thereby, the electrode laminated body 2 in which the anode lead 15 and the cathode lead 16 are assembled is obtained.

  Next, the electrode laminate 2 in which the leads 15 and 16 are assembled is accommodated in the case 3. The case 3 heats a portion other than the opening for inserting the electrode laminate 2 in the edge portion (seal portion) of the above-described film by a desired seal width under a predetermined heating condition using, for example, a sealing machine. Obtained by sealing. Then, after the electrode laminate 2 assembled with the leads 15 and 16 is accommodated in the case 3, an electrolytic solution is injected into the case 3. At this time, the electrode laminate 2 may be impregnated with an electrolytic solution. Subsequently, the opening of the case 3 is sealed using a vacuum sealer.

  Next, an aging process is performed. Here, the anode lead 15 is connected to the anode of the DC power source and the cathode lead 16 is connected to the cathode of the DC power source, and a DC voltage is applied between the anode foil 4 and the cathode foil 5. As a result, the damaged portion of the oxide film layer 8 of the anode foil 4 is repaired, and the oxide film layer is formed on the cut surface by punching the anode foil 4. Thus, the multilayer electrolytic capacitor 1 shown in FIG. 1 is obtained.

  By the way, when the anode lead 15 is connected to the surface of the lead portion 10 of the anode foil 4, the oxide film layer 8 on the surface of the lead portion 10 is destroyed. Since the anode lead 15 is connected to the lead-out portion 10 of the anode foil 4 of each layer, the number of broken portions of the oxide film layer 8 increases as the number of laminated anode foils 4 increases. The damaged portion of the oxide film layer 8 is repaired by using an electrolytic solution by aging treatment. However, if the number of repaired portions increases, it becomes difficult to reduce the leakage current, and a leakage current failure is likely to occur. Become. In order to avoid this, it is necessary to stably supply a sufficient electrolytic solution to the repaired portion of the oxide film layer 8.

  On the other hand, in the present embodiment, the connection covering portion 14 that covers the entire surface of the lead portion 10 including the connection fixing portion between the lead portion 10 and the anode lead 15 is provided on the separator 6A. It is supplied to the entire surface of the drawer 10. Therefore, a sufficient amount of electrolyte can be stably supplied to the repaired portion of the oxide film layer 8 without particularly putting a large amount of electrolyte in the case 3. As a result, the aging process is stabilized, and a capacitor leakage current failure can be prevented. In addition, there is no occurrence of liquid leakage as in the case where a large amount of electrolyte is placed in the case 3.

  In addition, since the separator 6A covers the entire surface of the anode foil 4, the electrolyte is supplied to the entire surface of the anode foil 4, so that the separator 6 </ b> A is also applied to the side surface of the anode foil 4 that is a cut surface by stamping the anode foil 4. The electrolyte is supplied. Therefore, the oxide film layer can be reliably formed on the side surface of the anode foil 4.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the connection covering portion 14 of the separator 6A covers the entire surface of the lead portion 10 of the anode foil 4, but as the connection covering portion 14, at least the lead portion 10 of the anode foil 4 and the anode lead 15 As long as it covers the fixed connection part of the cable.

  Moreover, in the said embodiment, although the shape of the separator 6A was made into the convex-shaped structure, if it has a connection coating | coated part which covers the connection fixing part of the drawer | drawing-out part 10 of the anode foil 4 and the anode lead 15, of separator 6A The shape is not particularly limited to a convex shape.

  Furthermore, in the said embodiment, although 2 types of separators, the separator 6A which has the connection coating | coated part 14, and the separator 6B which does not have the connection coating | coated part 14, were used, of course, you may use only the separator 6A.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
First, the anode foil base material on which the etching layer and the oxide film layer were formed was punched out so that the size of the main electrode portion was 17 mm × 32 mm, and an anode foil was obtained. Then, an anode lead made of an aluminum plain foil was prepared, the anode lead was brought into contact with the surface of the lead portion of the anode foil, and the anode lead member and each anode foil were connected by caulking. Further, the cathode foil base material was similarly punched out so that the size of the main electrode portion was 17 mm × 32 mm to obtain a cathode foil. Then, a cathode lead made of an aluminum plain foil was prepared, the cathode lead was brought into contact with the surface of the cathode foil lead portion, and the cathode lead and each cathode foil were connected by caulking. Thereafter, the anode foil and the cathode foil were alternately laminated via two kinds of separators so that the connection covering portion of the separator covered the entire surface of the lead portion of the anode foil, thereby obtaining an electrode laminate. Here, the anode foil has 5 layers, the cathode foil has 6 layers, and the separator has 12 layers.

  Moreover, after preparing two aluminum laminate foil used as a case and arrange | positioning an electrode laminated body between aluminum laminate foil, three sides of the aluminum laminate foil were sealed by heat sealing. Thereafter, an electrolytic solution was poured, and the remaining one side of the aluminum laminate foil was sealed by heat sealing. And the aging process was performed and the multilayer type electrolytic capacitor was produced.

(Comparative Example 1)
A multilayer electrolytic capacitor was produced in the same manner as in Example 1, except that a rectangular shape without an electrode laminate was used as the separator and the lead-out portion of the anode foil was not covered with the separator.

(Characteristic evaluation test of multilayer electrolytic capacitor)
100 multilayer electrolytic capacitors of Example 1 and Comparative Example 1 were produced, and each of the 100 multilayer electrolytic capacitors was subjected to an aging treatment, the leakage current value was confirmed, and the leakage current yield was evaluated. As a method for evaluating the leakage current yield, for example, a leakage current value of 100 μA or less was determined to be OK. The results are shown in Table 1.

  In Example 1, the leakage current yield was improved as compared with Comparative Example 1. In Example 1, the electrolyte foil impregnated in the separator is sufficiently supplied to the repaired portion of the oxide film layer by covering the connection fixing portion between the lead portion of the anode foil and the anode lead with the separator, and the leakage current in the aging process It is presumed that defects have been reduced.

DESCRIPTION OF SYMBOLS 1 ... Multilayer electrolytic capacitor, 2 ... Electrode laminated body, 3 ... Case, 4 ... Anode foil, 5 ... Cathode foil, 6A, 6B ... Separator, 9 ... Main electrode part, 10 ... Lead-out part, 11 ... Main electrode part, 12 ... Lead-out part, 14 ... Connection covering part, 15 ... Anode lead, 16 ... Cathode lead.

Claims (2)

An electrode laminate in which anode foil and cathode foil are alternately laminated via a separator, an anode lead connected to the anode foil, a cathode lead connected to the cathode foil, and electrolyzing the electrode laminate A multilayer electrolytic capacitor comprising a case for containing the liquid together;
The anode foil and the cathode foil have a main electrode portion facing each other through the separator, and a lead portion that is drawn from the main electrode portion and connected to the anode lead and the cathode lead, respectively.
The anode lead is connected and fixed to the surface of the lead portion of the anode foil,
The separator has a connection covering portion that covers a connection fixing portion between the lead portion of the anode foil and the anode lead. The multilayer electrolytic capacitor according to claim 1, wherein the connection covering portion covers the entire surface of the lead portion of the anode foil.

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