JP2008042079A - Electrolytic capacitor, and fabrication method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor fabrication method capable of assuring a sufficient connection area and forming a complete and good connection. <P>SOLUTION: A lead terminal is connected to an electrode foil equipped with an oxide film layer and an etching layer on its surface. The electrode foil is wound via a separator or stacked. A shield having an out-of-round opening with a long diameter and a short diameter is placed on an upper surface of the lead terminal connector of the electrode foil in a way that it keeps close contact with the electrolyte foil. The terminal connection part of the electrode foil composed of aluminum cored bar, etching layer and oxide film layer formed on the etching layer is irradiated with a predefined laser beam via the out-of-round opening to heat and melt an irradiation part, resulting in the formation of the connection part which allows lead connection. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrolytic capacitor and a method of manufacturing the same, and in particular, when a connection portion is formed by heating and melting a connection portion of an electrode foil and a lead terminal by laser irradiation, a large-diameter connection portion without a missing portion. The present invention relates to an electrolytic capacitor which has been improved so as to be formed, and a method for manufacturing the same.

  Conventionally, when manufacturing an electrolytic capacitor, for example, in the case of a winding capacitor, an electrode foil having an etching layer and an oxide film layer on the surface of a cored bar made of aluminum, a lead terminal is stitched, cold welded, ultrasonic welding, etc. To form a capacitor element by winding or laminating between electrode foils via a separator, impregnating the capacitor element with a driving electrolyte solution, and storing the capacitor element in an outer case to form an electrolytic capacitor. Yes.

  Among such electrode foils, the low pressure foil has a thick cored bar and a thin oxide film layer formed on the etching layer, whereas the high pressure foil has a thin cored bar and a thick oxidized layer on the etched layer. A film is formed.

  In such connection between the electrode foil and the lead terminal, it is necessary that the lead terminal is directly connected to the core metal portion of the electrode foil beyond the etching layer or oxide film layer on the surface of the electrode foil. Therefore, in particular, in the high-pressure foil having a thick oxide film, the reliability of the connection state between the electrode foil and the lead terminal is inferior.

  In order to solve such problems, various proposals have been conventionally made. For example, the oxide film on the lead terminal connection part of the electrode foil is mechanically removed beforehand by pressing or polishing, or electrically removed by arc or the like, and the lead terminal is crimped and connected to the removed part (For example, refer to Patent Document 1).

  In addition, the oxide film layer and the etching layer of the electrode foil lead-out terminal connection portion are rotated by sandwiching the electrode foil with a rough roller, or pulverized by contacting the electrode foil with an ultrasonic vibration device. In some cases, the lead-out terminal is crimped and connected to the removed portion (see, for example, Patent Document 2). Further, there is a method in which an oxide film is not formed on a connection portion in advance by performing a method such as cutting, grinding, breaking, folding, heat shock, or masking at the time of forming an oxide film (see, for example, Patent Document 3). ).

However, the conventional techniques disclosed in Patent Documents 1 to 3 described above have the following problems.
That is, in the method of mechanically removing the oxide film layer by pressing or polishing, or the method of mechanically removing the oxide film layer and the etching layer by a rotating roller or ultrasonic vibration, a removal jig is directly attached to the electrode foil. Since the oxide film layer and the etching layer are removed by contact with each other, mechanical stress at the time of contact is applied to the electrode foil itself, for example, the core metal part of the electrode foil and the oxide film layer and the etching layer in the vicinity of the removal part. As a result, damage, distortion, and the like occur, and a part of the removal jig is transferred to the electrode foil, thereby deteriorating the reliability of the electrode foil.

  In addition, when the oxide film layer and the etching layer are 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 causes a problem that the manufacturing process becomes complicated. . Furthermore, when the oxide film layer is electrically removed by an arc, it is difficult to control arc discharge phenomena such as adjustment of arc input energy and arc discharge position. The foil width was narrow and the removal range was limited. Further, in order not to form the oxide film in advance, it is necessary to perform masking or the like, and the process is complicated.

  Therefore, in order to solve the above problems, the present applicant has completed the invention as shown in Patent Document 4. That is, as shown in FIG. 4, an etching process is performed on a metal foil 16 made of a valve metal such as aluminum as the anode foil 10, and then a chemical conversion process is performed, whereby an etching layer and an oxide film formed on the layer are formed. A layer 18 is provided (FIG. 4A), and the cathode foil 6 is subjected to an etching treatment, and an oxide film layer is provided as necessary.

  Then, as shown in FIG. 4B, the laser source 24 is disposed on the electrode foils 6 and 10, and the lens 22 is disposed between the electrode foils 6 and 10 and the laser source 24. Then, the laser beam focused through a lens 22 at a predetermined portion of the oxide film layer 18 formed on the surface of the electrode foils 6, 10, that is, a portion connecting the lead terminals (hereinafter referred to as a connection portion). 20 is irradiated to heat a predetermined portion of the electrode foil.

  By this heating, the aluminum cored bar constituting the electrode foil, the etching layer, and the oxide film layer formed on the etching layer are melted to form the connection portion 30. Thereafter, a lead terminal is connected to the connecting portion 30 by cold welding or the like. After the connection, winding is performed between the anode foil 10 and the cathode foil 6 through a separator, and the winding end is fixed with a winding tape to form a capacitor element. Thereafter, the capacitor element is impregnated with a driving electrolyte, and is stored in a bottomed cylindrical metal case made of aluminum or the like, and sealed with a sealing member to obtain an electrolytic capacitor.

Japanese Utility Model Publication No. 54-164451 Japanese Patent Laid-Open No. 02-222517 JP 2000-82640 A JP 2006-100559 A

  According to the invention of Patent Document 4 as described above, a part of the electrode foil 16 serving as the connection portion of the lead terminal is locally heated by irradiating the laser beam, and the aluminum core metal and the etching layer of the portion are heated. And the oxide film layer formed on the etching layer can be melted to form a new connection portion 30, and the connection portion 30 is flat with no oxide film layer on the surface. At the same time, since the predetermined thickness can be maintained, the strength as the connection portion is increased, and a good connection with the lead terminal is possible.

  However, when trying to increase the diameter of the connecting portion in order to ensure the connection with the lead terminal, as shown in FIG. 5, from the tension “f” for maintaining the melting portion 40 as the connecting portion, The stress “g” such as reaction force due to laser irradiation becomes larger, and as a result, a part of the connection part is broken and a missing part is generated, so that the connection with the lead terminal becomes insufficient. There was a problem. Therefore, it has been desired to develop an electrolytic capacitor capable of forming a large-diameter connecting portion without a missing portion while sufficiently securing the area of the connecting portion and a manufacturing method thereof.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and its purpose is to form a connection portion when forming a new connection portion that can be connected to a lead terminal by laser irradiation. It is an object of the present invention to provide an electrolytic capacitor and a method for manufacturing the same that can form a good connection portion without a missing portion while ensuring a sufficient area.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a lead terminal is connected to an electrode foil having an oxide film layer and an etching layer on the surface, and this electrode foil is wound or laminated via a separator. In the electrolytic capacitor, the shape of the connection portion of the lead terminal formed by irradiating a predetermined laser beam to the lead terminal connection portion of the electrode foil to heat and melt the irradiation portion is reduced to a short diameter and a long diameter. It is characterized by having a non-round shape.

  According to the invention of claim 1 having the above-described configuration, by forming the shape of the connection portion formed by irradiating a predetermined laser beam into a non-circular shape having a minor axis and a major axis, Since the holding power of the melting part can be greatly improved, it is possible to form a good connection part with no missing part while ensuring a sufficient area of the connection part.

According to a second aspect of the present invention, in the electrolytic capacitor according to the first aspect, a ratio of the minor axis to the major axis of the non-circular connection portion is 1: 1.2 or more.
According to the invention described in claim 2 having the above-described configuration, the shape of the connecting portion is a non-circular shape having a minor axis and a major axis, and the ratio of the minor axis length to the major axis length is determined. By setting the ratio to 1: 1.2 or more, the holding power of the melted portion can be greatly improved, so that a good connecting portion without a missing portion is formed while sufficiently securing the area of the connecting portion. Can do. The ratio of the minor axis to major axis length of the connecting part is optimally from 1: 1.2 to 1: 2.

  The invention according to claim 3 is an electrolytic capacitor manufacturing method in which a lead terminal is connected to an electrode foil having an oxide film layer and an etching layer on the surface, and the electrode foil is wound or laminated via a separator. A shielding plate having a non-circular opening having a minor axis and a major axis is disposed on the upper surface of the lead terminal connecting portion of the electrode foil so as to be in close contact with the electrode foil, and an aluminum core bar and an etching layer are provided. By irradiating a predetermined laser beam to the lead terminal connecting portion of the electrode foil formed of the oxide film layer formed on the etching layer through a non-circular opening formed in the blocking plate The irradiated portion is heated and melted to form a connection portion, and the lead terminal is connected to the connection portion.

  According to the invention of claim 3 having the above-described configuration, the periphery of the processing target portion of the electrode foil is covered with the shielding plate having the non-circular opening having the minor axis and the major axis. A mask effect can be obtained, and high-energy laser light can be irradiated only to the processing target portion. In addition, by making the shape of the opening a non-circular shape having a minor axis and a major axis, it is possible to greatly improve the holding power of the melted part, so that the area of the connecting part is sufficiently secured while the missing part It is possible to form a good connection portion without any defects.

According to a fourth aspect of the present invention, in the method for manufacturing an electrolytic capacitor according to the third aspect, the ratio of the minor axis to the major axis of the non-circular opening is 1: 1.2 or more. And
According to the invention of claim 4 having the above-described configuration, the shape of the opening is a non-circular shape having a minor axis and a major axis, and the ratio of the minor axis length to the major axis length is By setting the ratio to 1: 1.2 or more, the holding power of the melted portion can be greatly improved, so that a good connecting portion without missing portions can be formed while sufficiently securing the area of the connecting portion. Can do. The ratio of the minor axis to major axis length of the connecting part is optimally from 1: 1.2 to 1: 2.

  Note that it is preferable to use a pulsed YAG laser beam as the laser beam. Since the pulse YAG laser has a relatively low light emission peak value per irradiation and a long light emission width, when the electrode foil is irradiated with the laser, sufficient heating is performed up to the opposite side of the irradiation side. The aluminum core metal, the etching layer, and the oxide film layer of the foil are melted and a good connection portion is formed.

  According to the present invention, when forming a new connection portion that can be connected to the lead-out terminal by laser irradiation, it is possible to form a good connection portion without a missing portion while ensuring a sufficient area of the connection portion. An electrolytic capacitor that can be used and a method for manufacturing the same can be provided.

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

(1) Configuration In this embodiment, as shown in FIG. 1, a shield having a non-circular opening 51 such as an ellipse, an oval, or a rectangle on the upper surface of a processing target portion of the electrode foils 6 and 10. The plate 50 is disposed in close contact with the electrode foils 6 and 10. In addition, the opening 51 formed in the shielding plate 50 is formed so that the ratio of the minor axis to the major axis is 1: 1.2 to 1: 2 in the case of an ellipse or an ellipse. In the case of a rectangle, the ratio of the short side to the long side is 1: 1.2 to 1: 2. Moreover, you may use the cooling plate which formed the same opening part instead of the shielding board.

  As described above, the opening 51 has a non-circular shape such as an ellipse, an ellipse, or a rectangle, and the ratio of the short diameter to the long diameter (or the ratio of the short side to the long side when the opening is rectangular). However, the reason why the ratio is 1: 1.2 to 1: 2 is as follows.

  That is, when a conventional manufacturing method as shown in FIG. 4 is used, a substantially circular connecting portion 30 as shown in FIG. 2A is formed. Of the substantially circular connection part 30, the connection part of the lead terminal is actually a rectangular part indicated by 30a in the figure.

  Here, as shown by an A curve in FIG. 3, it is assumed that the peak value of the energy of the laser beam irradiated to melt the processing target portion is “F1”, and the radius of the substantially circular connection portion 30 is “ In the case of R1 ”, the moment acting downward in the outer peripheral portion of the connecting portion 30 (the base end portion of the connecting portion 30) is expressed as“ F1 · R1 ”. Further, it is assumed that the radius “R1” of the substantially circular connection portion 30 is the maximum diameter that can maintain the connection portion without causing a missing portion in the connection portion 30.

  In addition, in the cross-sectional view of FIG. 2A, the outer peripheral portion of the connection portion 30 surrounded by a dotted circle (the base end portion of the connection portion 30) is a portion where a missing portion is likely to occur. Focusing on the moment “F1 · R1” acting on this part and reducing this moment “F1 · R1”, it is possible to prevent the occurrence of missing parts and to enlarge the connecting part, The present invention has been completed.

  In other words, the reason why the missing portion is likely to occur in the outer peripheral portion of the connection portion 30 is that when the stress such as a reaction force due to laser irradiation increases in the connection portion in the process of forming the connection portion by irradiating the laser, It is considered that aluminum is partially weakened at the base end portion that maintains the portion.

  Therefore, the present inventors examined the presence or absence of missing portions by changing the shape of the connecting portion as follows. That is, as shown in FIG. 2B, the energy distribution of the A curve in FIG. 3 is obtained through a shielding plate 50 having a non-circular opening 51 having a short side length of “2 × R2”. It was irradiated with laser light. In this case, the moment acting downward in the outer peripheral portion of the rectangular connection portion 31 (the base end portion of the long side of the connection portion 31) can be expressed as “F1 · R2”, but since R1> R2, F1 · Since R1> F1 · R2, the connecting portion 31 is not likely to be missing.

  Furthermore, the present inventors have increased the energy of the irradiated laser light while keeping the length of the short side at “2 × R2”, and increasing the length of the long side as much as possible to increase the diameter of the laser beam. We considered the formation of the connection part. As a result, “F2 · R2” equal to “F1 · R1”, which is the maximum value of the moment acting downward, is obtained, and the laser beam with the energy peak value “F2” (B curve in FIG. 3) is irradiated. However, it has been found that a large-diameter, generally rectangular connecting portion 32 in which no missing portion occurs is obtained. In this case, the maximum ratio of the short side to the long side of the opening 51 formed in the shielding plate 50 was 1: 2.

(2) Operation In the present embodiment having the above-described configuration, the connection portion is formed as follows. That is, as shown in FIG. 1, the light is focused through a lens 22 on a predetermined portion of the oxide film layer 18 formed on the surface of the electrode foils 6, 10, that is, a portion where the lead terminals 12, 14 are connected. By irradiating the laser beam 20 through a non-circular opening 51 formed in the shielding plate 50, a predetermined portion of the electrode foil is heated.

  By this heating, the aluminum core bar constituting the electrode foil, the etching layer, and the oxide film layer formed on the etching layer are melted to form a non-circular connection portion 31 such as an ellipse, an oval, or a rectangle. , 32 are formed. Thereafter, the lead-out terminals are connected to the connection portions 31 and 32 by cold weld, stitch or the like. After the connection, winding is performed between the anode foil 10 and the cathode foil 6 through a separator, and the winding end is fixed with a winding tape to form a capacitor element. Thereafter, the capacitor element is impregnated with a driving electrolyte, and is stored in a bottomed cylindrical metal case made of aluminum or the like, and sealed with a sealing member to obtain an electrolytic capacitor.

  As a laser beam to be irradiated, for example, a pulse YAG laser having a pulse width of 5 msec, a wavelength of 1064 nm, and an output of 4.3 J can be used. The pulse width is preferably 0.5 to 20 msec and the output is preferably 1 to 10 J. Since the pulse YAG laser has a relatively low emission peak value per irradiation and a long emission width, when the electrode foil is irradiated with the laser, sufficient heating is performed to the opposite side of the irradiation side, and the aluminum of the electrode foil The metal core, the etching layer, and the oxide film layer are melted to form a good connection portion. Further, the type of laser light to be irradiated is not particularly limited as long as it can heat and melt a predetermined portion of the electrode foil, and the number of times of irradiation is not particularly limited.

(3) Effect As described above, according to the present invention, the shielding plate having the non-circular opening 51 having the minor axis and the major axis on the upper surface of the processing target portion of the electrode foil serving as the connecting portion of the lead terminal. After installing 50, only the part to be processed is locally heated by irradiating a laser beam to melt the aluminum cored bar, the etching layer, and the oxide film layer formed on the etching layer. Thus, a new non-circular connection portion having a minor axis and a major axis can be formed. In addition, since this connection part has an oxide film layer on the surface and is flat and can maintain a predetermined thickness, the strength as the connection part is increased, and thereby a good connection with the lead terminal is achieved. It becomes possible.

  In particular, according to the present embodiment, the shape of the connecting portion is a non-circular shape such as a rectangle, an ellipse, or an oval, and the ratio of the length of the minor axis to the length of the major axis (when the connecting portion is rectangular) Since the ratio of the short side to the long side) is 1: 1.2 to 1: 2, the holding power of the melted portion can be greatly improved, so that the area of the connecting portion is sufficiently secured. It is possible to form a good connection portion without any missing portion.

(4) Other Embodiments Although the winding type electrolytic capacitor has been described in the above embodiment, the cathode lead terminal is connected to the cathode foil, the anode lead terminal is connected to the anode foil, and the electrode foil is interposed between the electrode foils. The present invention can also be applied to a multilayer electrolytic capacitor in which a plurality of electrode foils are alternately stacked with a separator interposed therebetween.

In the present invention, as a laser used for heating and melting aluminum and an oxide film layer, in addition to a pulse YAG laser, a semiconductor laser having a wavelength suitable for laser irradiation to aluminum can be used. An excimer laser, a CO ₂ laser, or the like can also be used. Further, the welding means used in the present invention includes stitch, cold weld, ultrasonic welding, friction stir welding, laser welding and the like.

  Further, in the present invention, when the laser beam 20 from the laser source 24 is focused by the lens 22 and irradiated to a predetermined site, the area and laser energy of the laser beam 20 irradiated by changing the shape and irradiation distance of the lens 22 are changed. Can be easily changed.

Further, when an inert gas such as helium gas or argon gas is blown onto a predetermined portion when the laser beam 20 is irradiated, the surface state of the connection portion of the electrode foil becomes good.
Further, when a carbon layer is provided at the lead terminal connecting portion of the oxide film layer and the carbon layer is irradiated with the laser beam 20, heat absorption of the oxide film layer 18 and the etching layer is enhanced, so that heating and melting can be promoted. it can. Alternatively, first, at least a portion of the oxide film layer 18 is melted by irradiating the laser beam 20, and then a carbon layer is provided on the surface, and the laser beam 20 is further irradiated to increase the heating and melting speed.

  Further, in the present invention, a part of the oxide film layer may be removed in advance from the lead terminal connection portion of the electrode foil, and a new connection portion may be formed by heating and melting in this state. As a method for removing the oxide film layer, there are grinding, cutting, polishing, laser irradiation, arc, ultrasonic vibration, chemical treatment, and the like. Since the connection portion thus formed is in a state in which the oxide film layer has been removed in advance, the absolute amount of the oxide film layer in the formed connection portion can be reduced, and therefore a good connection portion with low resistance can be obtained. It is formed.

The conceptual diagram which shows the manufacturing method of the winding type aluminum electrolytic capacitor by this invention. It is a conceptual diagram which shows the effect of the manufacturing method of the winding type aluminum electrolytic capacitor by this invention, Comprising: (A) is the connection part by the conventional manufacturing method, and the outer peripheral part (base end part of a connection part) of the connection part. The figure which shows the moment which acts, (B) * (C) is the figure which shows the moment which acts on the connection part by the manufacturing method by this invention, and the outer peripheral part (base end part of the long side of a connection part) of the connection part. The figure which shows the relationship between the energy distribution of the irradiated laser beam, and the connection part formed. It is a conceptual diagram which shows the manufacturing method of the conventional winding type aluminum electrolytic capacitor, (A) is sectional drawing which shows the state which formed the oxide film layer 18 and the etching layer on both surfaces of the aluminum core metal 16, ) Is a cross-sectional view showing a state in which a portion corresponding to the connecting portion of the lead terminal of the electrode foils 6 and 10 is heated and melted. It is a figure which shows the tension | tensile_strength which acts on the fusion | melting part used as a connection part, Comprising: (A) is a top view, (B) is sectional drawing.

Explanation of symbols

6 ... Cathode foil 10 ... Anode foil 16 ... Metal foil (aluminum core)
DESCRIPTION OF SYMBOLS 20 ... Laser beam 22 ... Lens 24 ... Laser source 30 ... Connection part 31 ... Void 40 ... Melting part 50 ... Shielding plate 51 ... Opening part

Claims (4)

In an electrolytic capacitor in which a lead terminal is connected to an electrode foil having an oxide film layer and an etching layer on the surface, and this electrode foil is wound or laminated via a separator,
A shape of the connecting portion of the lead terminal formed by irradiating the lead terminal connecting portion of the electrode foil with a predetermined laser beam to heat and melt the irradiated portion is a non-circular shape having a short diameter and a long diameter. An electrolytic capacitor characterized by its shape.   2. The electrolytic capacitor according to claim 1, wherein a ratio of a minor axis to a major axis of the non-circular connection portion is 1: 1.2 or more. In the method of manufacturing an electrolytic capacitor in which a lead terminal is connected to an electrode foil having an oxide film layer and an etching layer on the surface, and this electrode foil is wound or laminated via a separator.
A shielding plate having a non-circular opening having a minor axis and a major axis is disposed on the upper surface of the lead terminal connecting portion of the electrode foil so as to be in close contact with the electrode foil,
A predetermined portion of the electrode foil made of an aluminum cored bar, an etching layer, and an oxide film layer formed on the etching layer is connected to the lead terminal connection portion through a non-circular opening formed in the blocking plate. A method of manufacturing an electrolytic capacitor, comprising: irradiating a laser beam to heat and melt the irradiated portion to form a connection portion, and connecting the lead terminal to the connection portion.   The method for manufacturing an electrolytic capacitor according to claim 3, wherein the ratio of the minor axis to the major axis of the non-circular opening is 1: 1.2 or more.

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