JP2005045078A - Method for manufacturing electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the contact status of projecting parts being the connecting parts of stable electrode foils without generating any burr at the time of mechanically removing an oxide film layer in the removal section of an electrode foil in a laminated electrolytic capacitor, or generating any damage or distortion due to the application of the mechanical stress. <P>SOLUTION: In an electrolytic capacitor configured by forming an oxide film layer and an etching layer on the surface, and laminating a plurality of electrode foils having projecting parts constituted by projecting a portion from the edge through a separator, the oxide film layer formed on the projecting part is removed by laser irradiation, and those respective projecting parts are connected to each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrolytic capacitor and a manufacturing method thereof, and in particular, a stable connection state is achieved by removing a non-contact oxide film layer in a protruding portion which becomes a connection portion between electrode foils by laser irradiation. The present invention relates to an electrolytic capacitor and a manufacturing method thereof.

Conventionally, when manufacturing an electrolytic capacitor, for example, in the case of a multilayer electrolytic capacitor, an etching foil and an oxide film layer are formed on the surface, and an anode foil made of aluminum with a protruding portion as a connecting portion on the end, and on the surface An etching layer and an appropriately selected oxide film layer are formed, and a cathode foil made of aluminum having a protruding portion as a connecting portion at the end portion is arranged so that the protruding portions do not contact each other via a separator. A multilayer electrolytic capacitor element is formed by laminating a plurality of layers, and this capacitor element is impregnated with a driving electrolytic solution and housed in an outer case to form an electrolytic capacitor (see, for example, Patent Document 1).
JP-A-5-326340 (all pages, all figures)

  However, in the multilayer electrolytic capacitor, when connecting the protruding portions of the electrode foil, an oxide film layer is provided on the surface of each electrode foil, and this oxide film layer has been reduced in size and capacity in recent years. In this demand, the electrode foil has a higher magnification, that is, deeper etching and miniaturization, and the insulating oxide film layer formed on the higher-magnification etching layer is the protrusion of the electrode foil. Since it is interposed between the connecting parts of the parts, it has an adverse effect on the electrical connectivity of the electrode foil, and as the number of laminated electrode foils increases, the electrical connectivity of the electrode foils is further adversely affected. End up.

  Therefore, in order to improve the connection of each electrode foil, the oxide film layer is not connected between the protruding portions of the electrode foil to be connected, that is, directly connected to the metal foil portion of the electrode foil, It has been found that a good connection state, that is, contact resistance can be reduced and connection strength can be increased.

  In the method for manufacturing an electrolytic capacitor according to the present invention, an oxide film formed on the protruding portion of the electrode foil having an oxide film layer and an etching layer on the surface and having a protruding portion partially protruding from the end portion The layers are removed, and a plurality of layers of the electrode foil and the separator are alternately laminated, and the protrusions are connected to each other.

  Examples of the method for removing the oxide film layer include a mechanical removal method by pressing, polishing, a rotating roller and ultrasonic vibration, and an electric removal by an arc. In this mechanical removal method, the electrode foil is directly applied. Since the oxide film layer and the etching layer are removed by bringing the removal jig into contact, mechanical stress at the time of contact is caused on the electrode foil itself, for example, the metal foil portion of the electrode foil and the oxide film layer near the removal portion and When added to the etching layer, damage or distortion occurs, and a part of the removal jig may be transferred to the electrode foil, which may deteriorate the reliability of the electrode foil. When the etching layer is mechanically removed, burrs or the like are generated in the removed portion, and it is necessary to add a process for removing the burrs, which may complicate the manufacturing process. Because it is difficult to control the arc discharge phenomenon such as the adjustment of arc input energy and the arc discharge position, for example, the foil width of electrode foils such as small products is narrow and the removal range is limited. Since it is not suitable for removing the oxide film layer, the removal jig can be removed without contact directly with the oxide film layer when removing the oxide film layer, and there is no damage or distortion due to the application of the mechanical stress. In addition, it is preferable to use a method of removing the oxide film layer by laser irradiation that does not generate burrs or the like and can achieve a stable contact state between the electrode foils.

  In addition, when removing at least the oxide film layer by laser irradiation, two laser devices may be used to remove both surfaces simultaneously, or one laser device may be used to remove the other surface and turn it over. May be removed. The oxide film layer on one side may be simply removed by laser irradiation.

  Furthermore, when laser irradiation is performed, an inert gas may be sprayed on the removed portion, and the melt remaining without being heated and evaporated may be blown off and removed. Further, the laser irradiation may be performed a plurality of times to remove the oxide film layer stepwise, or carbon may be disposed in advance on the portion to be removed when laser irradiation is performed. Furthermore, it is preferable to connect the protrusions of the electrode foil by friction stir welding.

  As described above, according to the present invention, in the multilayer capacitor, by removing the oxide film layer of the electrode foil, it is directly connected to the bare metal portion of the electrode foil beyond the oxide film layer. A good connection state, that is, contact resistance can be reduced and connection strength can be increased.

  Further, by removing the oxide film layer in a non-contact manner by laser irradiation, burrs and the like generated when the oxide film layer and the etching layer are mechanically removed are not generated in the removed portion of the electrode foil.

  Further, according to the present invention, stress due to the mechanical removal method is not applied to the oxide film layer or the etching layer in the vicinity of the bare metal portion or the removed portion of the electrode foil, so that the electrode foil itself is not distorted or damaged. It does not occur, and when the mechanical removal is performed, a part of the removal jig that directly contacts the electrode foil is transferred to the electrode foil. A connection state between the terminal and the electrode foil can be achieved.

  Furthermore, when removing at least the oxide film layer of the electrode foil connection parts that are stacked on top of each other, the thickness of the oxide film layer or the etching layer is limited when the foil width is small and the connection part is limited, such as small products. Can be easily removed by adjusting the laser light irradiation area and laser energy during laser irradiation.

  As a result, in the multilayer electrolytic capacitor, the joining property of the aluminum ingot at the connecting portion of the electrode foil is improved.

  Further, since burrs or the like are not generated in the removed portion, a process for removing the burrs is not required, and the manufacturing process is simplified, so that cost reduction can be realized.

  By improving the surface condition of the removed portion by laser irradiation, it becomes possible to manufacture a high-quality capacitor that does not generate additional capacitance at the contact portion, and the yield is improved.

  By removing by laser irradiation, it becomes possible to manufacture a high-quality product even with a low-precision welding machine that does not require accuracy during welding, and a high-precision welding machine is no longer necessary, thereby reducing costs.

  By removing by laser irradiation, the accuracy of the shape of the removed part has been improved, and it has become possible to eliminate the unnecessary part of the laser irradiation, thus shortening the manufacturing process time and reducing the time to use the laser. Therefore, it can contribute to the realization of cost reduction and further countermeasures for environmental problems.

  Further, when the laser irradiation is performed, an inert gas is blown onto the removed portion, so that the melt is removed even when the melt remains without being evaporated by heating, so that the surface state of the removed portion is improved. , Contact is improved, and high quality capacitors can be manufactured.

  By performing laser irradiation a plurality of times and removing at least the oxide film layer stepwise, it is possible to remove to a desired depth.

  Furthermore, by providing a carbon layer on the surface of the oxide film layer or the etching layer in the laser irradiation according to the present invention, it is possible to easily remove the layer by increasing the heat absorption of each layer and promoting the evaporation by heating.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The multilayer electrolytic capacitor according to the present invention will be described with reference to FIGS.

  In this multilayer electrolytic capacitor element 2, as shown in FIG. 1, anode foil 6 and cathode foil 8 are alternately laminated via separator 4, and the protrusions 10 and 12 are arranged separately for anode and cathode. Weld each.

  In each of the electrode foils 6 and 8, an oxide film layer 18 and an etching layer are formed on the aluminum base metal 16. Protrusions 10 and 12 are provided at one end portions of the electrode foils 6 and 8, respectively, and the projecting portions 10 of the anode foil 6 project near the corners of one side, and the projecting portions 12 of the cathode foil 8 are the projecting portions 10. And projecting in the vicinity of other adjacent corners on the same side. The portions of the oxide film layer 18 corresponding to the protrusions 10 and 12 are removed by a laser beam 20, and the protrusions 10 of the anode foil 6 and the protrusions 12 of the cathode foil 8 are connected by friction stir welding.

  A method for manufacturing a multilayer electrolytic capacitor will be described with reference to FIGS.

  First, an oxide film layer 18 and an etching layer are formed on both surfaces of a metal foil made of a valve action metal such as aluminum by etching treatment and chemical conversion treatment, and a protruding portion 10 or 12 is provided and punched out into a square shape. 8 (FIG. 2A). The formation of the oxide film layer on the cathode foil can be appropriately selected.

  FIG. 3 shows an example of this electrode foil. An anode foil is shown as an example, but a laser source 24 is disposed above and below the anode foil, and a lens 22 is disposed between the anode foil 6 and the laser source. Laser light 20 is applied to the anode foil 6 from the upper and lower laser sources 24. When the oxide film layer 18 on both surfaces of the protruding portion 10 is removed by this laser irradiation (FIG. 3A) and the etching layer is also removed, the protruding portion 10 becomes a connecting portion 36 where the aluminum ingot 16 is exposed on both surfaces. (FIG. 2 (b)). It is preferable to remove the oxide film layer 18 including the etching layer because the aluminum ingot 16 is exposed flatly on the surface of the removed portion, but at least a part of the oxide film layer 18 in the connection portion 36 is removed. Then, the etching layer may be exposed at a part of the surface of the removed portion. The oxide film layer 18 on the protrusion 12 of the cathode foil 8 is also removed in the same manner.

  The anode foil 6 from which the aluminum ingot 16 of the protruding portion 10 is exposed is sandwiched and held by the separator 4 that is one size larger.

  The anode foil 6 and the separator 4 are overlapped, and the cathode foil 8 and the separator 4 are further overlapped to integrate each other (FIG. 3C). The integrated anode foil 6 and separator 4 and the integrated cathode foil 8 and separator 4 are alternately laminated a plurality of times and fixed with a winding tape. At that time, the end portions of the connection portions 36 of the anode foil 6 and the end portions of the connection portions 37 of the cathode foil 8 are aligned, and the connection portions 36 and 37 are laminated so as not to contact each other. Thereafter, the connecting portions 36 are collectively welded and connected by friction stir welding (FIG. 3B), the connecting portions 37 are also connected in the same manner (not shown), and the multilayer electrolytic capacitor element 2 is connected. Form.

  Thereafter, the connection portions 36 and 37 of the multilayer electrolytic capacitor element 2 are attached to external terminals provided on the sealing member, impregnated with a driving electrolyte, and stored in a bottomed square metal case made of aluminum or the like, The multilayer electrolytic capacitor is completed by sealing with a sealing member.

  In the embodiment, friction stir welding is used as a method for welding the anode foil connecting portions 36 together. The friction stir welding will be described in detail. As shown in FIG. The parts 36 are put together, arranged on the welding base 32, and a probe 34 provided at the tip of the star rod 28 rotating from above the connecting part 36 is press-fitted, and the tip of the probe 34 is laminated downward. When the connecting portion 36 is reached, the star rod 28 moves linearly or in a meandering manner in the direction of the arrow in the drawing, and the aluminum base metal 16 portion of the connecting portion 36 in the moving direction and part of the oxide film layer 18 remaining in the moving direction by rotation of the probe 34. And the etching layer are heated and softened, and are agitated and solidified in the moving direction of the probe 34, so that the aluminum ingots 16 serving as the anode foil connecting portions 36 are firmly solid-phase bonded. It is. In addition, the connection part 37 of the cathode foil 8 is connected similarly. Hereinafter, the anode foil 6 and the cathode foil 8 will be collectively described as electrode foils.

  Here, the star rod 28 is press-fitted at an angle of 2 to 5 degrees with respect to the moving direction so that the probe 34 precedes the star rod 28, and the length of the probe 34 is a combined electrode foil connection portion. It is preferable to set it to the extent of reaching below 36 and 37. Further, when performing friction stir welding, aluminum having a thickness of 0.2 to 1.0 mm is preferably provided on at least one side of the combined electrode foil connecting portions 36 and 37, preferably on the star rod 28 press-fitting side, and more preferably on both sides. It is preferable to arrange a reinforcing plate 30 made of the above metal. As a result, deformation and breakage are less likely to occur due to the press-fitting and rotation of the probe 34 of the star rod 28 above the combined electrode foil connecting portions 36 and 37, and the star rod 28 can be rotated at a speed such as the rotational speed and moving speed. Control during welding by the rod 28 is facilitated.

  Further, the friction stir welding will be described in detail. The probe 34 press-fitted into the joint portions 36 and 37 of the integrated electrode foil is moved in the direction perpendicular to the stacking direction, that is, all the stacked electrode foils that come into contact with the probe 34 are contacted. Since all the connecting portions 36 and 37 can be solidified by heating, softening, stirring and solidifying, the length of the probe 34 of the star rod 28 is changed, so that it is not restricted by the laminated thickness. Even when a large number of layers are stacked, welding can be stably performed. On the other hand, as another welding method, for example, in ultrasonic welding or cold weld, the welding energy is injected in the laminating direction into the connecting portions 36 and 37 of the combined electrode foil, so that they are laminated. The connection portions 36 and 37 are connected to each other by the welding energy. However, when a large number of the connection portions 36 and 37 are stacked, the connection portions stacked below are difficult to transmit the welding energy. Since the connection state at is uneven, the number of stacked layers is limited. For this reason, friction stir welding is particularly suitable for welding the connection portion of the multilayer electrolytic capacitor. In this friction stir welding, even if the oxide film layer 18 and the etching layer are partially present in the combined electrode foil connecting portions 36 and 37, the probe 34 causes the oxide film layer 18, the etching layer and the electrode to be present. Since the foil including the bare metal portion is stirred and welded, the connection state of the connecting portion is stable. However, particularly in electrode foils used for low pressure products and the like, the formed oxide film layer 18 and etching layer are hard, and it may be difficult to perform temperature rise, softening and stirring by the probe 34 during welding. Therefore, in a state where the oxide film layer 18 does not exist as much as possible, for example, the oxide film layer 18 formed on the connection portions 36 and 37 of the electrode foil is removed by laser irradiation, polishing, pressing, ultrasonic vibration, etc. Stir welding is preferably performed, and in particular, a removal method by laser irradiation that can easily and selectively remove a predetermined portion of the oxide film layer 18 at the electrode foil connecting portions 36 and 37 is preferable.

  Here, FIG. 4 shows the shape of the removed portion in which at least the oxide film layer 18 is removed by laser irradiation in the connection portions 36 and 37 of the multilayer electrolytic capacitor element 2. The shape of the removed portion is appropriately set based on the connection method of the electrode foil connecting portions 36 and 37. For example, FIG. 4A shows a case where the oxide film layer of the entire overlapping connection portions 36 and 37 is removed, which is easily connected regardless of the welding method such as stitching, cold weld, ultrasonic welding, friction stir welding, and the like. In addition, as shown in FIG. 4B, the oxide film layer 18 is removed in the projecting direction of the electrode foil connecting portions 36 and 37 so as to be adapted to the connecting line for friction stir welding, or FIG. As shown in (c), the oxide film layer 18 of the electrode foil is dot-like or partly removed at intervals, and the stitch needle shape and arrangement interval of stitches, the shape and arrangement of contacts of cold weld and ultrasonic welding are arranged. It can also be adapted to the spacing. When the removal method by laser irradiation that enables removal of only a specific small space is used as described above, the oxide film layer 18 can be removed in conformity with the form of the connection part of various welding methods. By removing the oxide film layer 18 only at the part that is actually connected, the stability of the connection can be ensured with only a partial removal. The removed portions 42 and 44 are obtained by partially removing at least the oxide film layer 18 in the connecting portions 36 and 37. In addition, the connecting portions 36 and 37 of the electrode foils that overlap each other may have a lattice shape or Connection strength generated at the time of connection by removing the oxide film layer 18 in a radial manner, continuously or at intervals, and removing the oxide film layer 18 in at least a part of the connection portions 36 and 37 by various welding methods. It is also possible to prevent deterioration of contact resistance.

  As a component of the driving electrolyte solution in the present invention, ethylene glycol, water, sulfolane, γ-butyl lactone or the like is used alone or as a mixed solution as a solvent of the driving electrolyte solution, and an acid conjugate base is used as an anion component as a solute. Ammonium salts, amine salts, quaternary salts of cyclic amidine compounds, adipic acid, benzoic acid, phthalic acid, boric acid, 1,6-decanedicarboxylic acid and the like are used as anionic components.

In the present invention, excimer laser, YAG laser, and CO ₂ laser are suitable as lasers used for removing the oxide film layer 18 and the etching layer, but are not limited thereto.

  The separator 4 used in the present invention is composed of electrolytic paper such as kraft paper or manila paper, non-woven fabric, film, or mixed paper thereof.

  As welding means used in the present invention, there are stitch, cold weld, ultrasonic welding, friction stir welding and the like.

  In the present invention, when the laser beam 20 from the laser source 24 is focused by the lens 22 and irradiated to the removal portion, the area of the laser beam 20 and the laser energy are easily changed by changing the angle of the lens 22. be able to.

  Moreover, it becomes possible to remove to the desired depth by irradiating the oxide film layer 18 and the etching layer with the laser beam 20 a plurality of times.

  As another embodiment of the present invention, when an inert gas such as helium gas or argon gas is blown onto the removed portion when irradiating the laser beam 20, even if there is a melt that is not heated and evaporated, the melt Since the object is removed, the surface state of the electrode foil connecting portion 36 is improved (not shown).

  As another embodiment of the present invention, when at least the oxide film layer 18 is removed by irradiating the laser beam 20, a carbon layer is provided on the surface of the oxide film layer 18 at the removed portion, and the carbon layer By irradiating the laser beam 20, the heat absorption of the oxide film layer 18 and the etching layer can be increased, and the evaporation can be facilitated to facilitate removal. Alternatively, first, at least a portion of the oxide film layer 18 is removed by irradiating the laser beam 20, and then a carbon layer is provided on the surface thereof and irradiating the laser beam 20 to increase the removal speed.

It is explanatory drawing which shows the structure of the multilayer electrolytic capacitor by this invention, Comprising: The state which laminated | stacked the anode foil 6 and the cathode foil 8 which each provided the protrusion parts 10 and 12 via the separator 4 alternately is shown. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram which shows the manufacturing method of the multilayer electrolytic capacitor by this invention, Comprising: (a) is the electrode foil 6 and 8 in which the oxide film layer 18 and the etching layer were formed, provided the protrusion part 14, and was punched squarely. (B) shows a state in which at least the oxide film layer 18 of the projecting portion 14 is removed and the connecting portion 36 is formed. It is explanatory drawing which shows the manufacturing method of the multilayer type electrolytic capacitor by this invention, Comprising: (a) is sectional drawing of the state from which at least the oxide film layer 18 of both surfaces of anode foil was removed by laser irradiation, (b) is friction stirring. The figure which showed the method of welding the anode foil connection part 36 of the multilayer electrolytic capacitor element 2 by welding, (c) is the figure which looked at the state from which anode foil and the separator were united from the top. It is a conceptual diagram which shows the manufacturing method of the multilayer electrolytic capacitor element 38 by this invention, Comprising: It is an example of the shape from which the oxide film layer 18 is removed at least, (a) shows at least the oxide film layer 18 of the protrusion part 14 whole. (B) is a state in which at least the oxide film layer 18 of the protrusion 14 is linearly removed by friction stir welding or the like, and (c) is at least an oxide film of the protrusion 14 by stitching, cold weld, ultrasonic welding or the like. The state where the layer 18 is removed in the form of dots is shown.

Explanation of symbols

2 Stacked Electrolytic Capacitor Element 4 Separator 6 Anode Foil 8 Cathode Foil 10 Anode Protrusion 12 Cathode Protrusion 14 Protrusion 16 Aluminum Ingot 18 Oxide Film Layer 20 Laser Light 22 Lens 24 Laser Source 28 Star Rod 30 Reinforcement Plate 32 Welding Table 34 Probe 36 Anode foil connection portion 37 Cathode foil connection portion 40 Overall removal portions 42 and 44 Partial removal portions

Claims (6)

  The oxide film layer formed on the protruding portion of the electrode foil having the oxide film layer and the etching layer on the surface and the protruding portion at the end is removed, and the electrode foil and the separator are alternately laminated in a plurality of layers. And the manufacturing method of the electrolytic capacitor which connects the said protrusion part mutually.   The method for producing an electrolytic capacitor according to claim 1, wherein the oxide film layer is removed by laser irradiation.   The method for producing an electrolytic capacitor according to claim 2, wherein, when the laser irradiation is performed, an inert gas is blown onto the removed portion to remove the remaining melt without being heated and evaporated.   The method for producing an electrolytic capacitor according to claim 2, wherein the laser irradiation is performed a plurality of times, and the oxide film layer is removed stepwise.   The method for producing an electrolytic capacitor according to any one of claims 2 to 4, wherein carbon is preliminarily disposed on the portion to be removed when the laser irradiation is performed.   The method for manufacturing an electrolytic capacitor according to claim 1, wherein the stacked protrusions are connected by friction stir welding.

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