JP2005109280A - Capacitor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor provided with satisfactory connections between electrode foil and lead-out terminals, and to provide a method of manufacturing the capacitor. <P>SOLUTION: The capacitor is manufactured by housing a capacitor element, which is constituted by connecting the lead-out terminals 2 to the electrode foil 1 and laminating or winding the electrode foil 1 with a separator in between, in an encapsulating case and, at the same time, sealing the opened end of the case with a sealing member. In the method of manufacturing the capacitor, reinforcing substrates 7 are arranged, in at least parts of the connections 3 between the electrode foil 1 and lead-out terminals 2, and the terminals 2 are electrically and mechanically connected to the electrode foil 1 by performing friction agitation welding. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a connection structure between an electrode foil and a lead terminal in various capacitors such as an electrolytic capacitor and a manufacturing method thereof.

  Conventionally, as a capacitor, an anode foil in which a surface of a metal foil made of a valve metal such as aluminum is subjected to a surface expansion treatment for expanding the surface area and a chemical conversion film as a dielectric layer is formed by anodization, and the aluminum A metal foil-shaped lead terminal is connected to a cathode foil that has been subjected only to the surface expansion treatment on the surface of a metal foil made of a valve metal such as the anode foil and the cathode as an electrically insulating separator made of insulating paper, etc. Using an electrolytic capacitor element formed by being laminated or wound interposed between foils, or forming an activated carbon layer on both surfaces of a metal foil made of a valve metal such as aluminum to form a polarizable electrode foil, A lead terminal is connected to a polarizable electrode foil and laminated or wound by interposing it as an electrically insulating separator made of insulating paper or the like between the polarizable electrode foil which is a pair of an anode and a cathode From these capacitor elements, lead terminals connected to the electrode foil are led out and connected to external terminals provided on a sealing member, etc. The capacitor element is housed in an outer case and the opening is sealed with the sealing member, thereby forming an electrolytic capacitor or an electric double layer capacitor. (Patent Document 1)

JP-A-4-154106

  In a capacitor using these capacitor elements, it is necessary to electrically and mechanically connect the electrode foil and the lead terminal, and stitches or ultrasonic welding is mainly used as the technique.

  However, when the electrode foil and the lead terminal are connected by ultrasonic welding, an etching layer and a chemical film layer are formed on the surface of the valve action metal foil such as aluminum by etching treatment and chemical conversion treatment on the electrode foil. Therefore, in the connection part by ultrasonic welding, a boundary line remains between the electrode foil and the lead terminal, and when used in a place where vibration such as an automobile occurs, the stress due to the vibration is Concentrating on the part, peeling from between the metal foils at the connecting part is more likely to occur, and the connection strength and electrical connectivity are not sufficient.

  In addition, when the electrode foil and the lead terminal are connected by stitching, the electrode foil and the lead terminal are overlapped, the stitch needle is pierced, the leaf is folded, and the electrode foil and the lead terminal are connected. The connection strength of the connection portion was low due to the folding, and the connection reliability was not sufficient.

  Therefore, the present invention has been made paying attention to the above-mentioned problems, and regardless of the etching layer or oxide film formed on the electrode foil, a capacitor having a good connection between the electrode foil and the lead terminal, It aims at providing the manufacturing method.

In order to solve the above-described problems, the capacitor of the present invention has an outer case in which a capacitor element is formed by connecting a lead terminal to an electrode foil electrically and mechanically by friction stir welding, and laminating or winding the electrode foil. It is characterized by being housed in.

  Further, it is preferable that the lead terminal is folded and the electrode foil is disposed therebetween.

  Moreover, it is preferable that a reinforcing base material is disposed on at least a part of the lead terminal or the electrode foil, and a part of the reinforcing base material is connected to the electrode foil by friction stir welding.

  In addition, the method for manufacturing a capacitor in the present invention includes connecting a lead terminal to an electrode foil, laminating or winding the electrode foil via a separator to form a capacitor element, and storing the capacitor element in an outer case. In the method of manufacturing a capacitor in which the opening end of the outer case is sealed with a sealing member, a reinforcing base material is disposed on at least a part of the connection portion between the electrode foil and the lead terminal, and the electrode foil is obtained by friction stir welding. The lead terminal is electrically and mechanically connected.

  Further, the present invention is characterized in that a temporary joining state having almost no gap between the electrode foil and the lead terminal is performed, and the friction stir welding is performed in the temporary joining state.

  Further, the method for setting the temporary bonding state includes caulking by pressing the electrode foil and the lead terminal.

  Moreover, the method for setting the temporary joining state includes ultrasonic welding, cold weld, and arc welding.

  According to this feature, by connecting the electrode foil and the lead terminal by friction stir welding, even if the surface of the electrode foil has an etching layer or a chemical conversion coating layer, these etching layer or chemical conversion coating layer is Because it is destroyed by the rotation of the probe in friction stir welding, the base metal melts and integrates, and the electrode foil and the extraction terminal are metal-bonded, so the electrode foil and the extraction terminal regardless of the presence or absence of the etching layer or chemical conversion coating layer A capacitor having a good electrical and mechanical connection with can be obtained.

  Further, by folding the lead terminal and disposing the electrode foil therebetween, position control between the electrode foil and the lead terminal is facilitated, and friction stir welding is facilitated.

  In addition, a reinforcing base material is disposed on at least a part of the lead terminal or the electrode foil, and a part of the reinforcing base material is connected to the electrode foil by friction stir welding, thereby connecting the electrode foil and the lead terminal. Becomes solid.

    Next, according to the method for manufacturing a capacitor in the present invention, since the reinforcing base material is disposed on at least a part of the connection portion between the electrode foil and the lead terminal, in addition to the electrode foil and the lead terminal by friction stir welding, A part of the reinforcing substrate is heated and softened by the rotation of the probe, and is agitated and integrated, so that a stronger electrical and mechanical connection can be obtained.

  In addition, it is possible to obtain a good connection portion with no defects in the welded portion by performing the friction stir welding in the temporary joined state having almost no gap between the electrode foil and the lead terminal and performing the friction stir welding in the temporary joined state. Can do.

  In addition, the method of setting the temporary bonding state includes caulking the electrode foil and the lead terminal by pressurization, thereby deforming the electrode foil and the lead terminal to reduce a gap, thereby reducing defects in the welded portion, A good connection between the foil and the lead terminal can be obtained.

  In addition, the method of setting the temporary bonding state may be applied by ultrasonic welding, cold weld, or arc welding to deform the electrode foil and the lead terminal to reduce the gap, and the temporary connection is relatively performed. Since the friction stir welding is performed in a firmly fixed state, defects are not easily generated, and a better connection can be obtained.

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

(Example)

The capacitor of this embodiment is a fixed cylindrical outer case that can accommodate a capacitor element in which anode foils 1 and anode foils each connected to a lead terminal 2 are laminated or wound via an electrically insulating separator. And has the same appearance as a general capacitor sealed with a sealing member formed through an external terminal.

  The anode foil 1 and the cathode foil are formed from a valve action metal such as aluminum, titanium, tantalum, niobium, etc., and the anode foil 1 has an etching treatment layer formed by etching treatment that is surface-enhanced on the surface thereof, and the etching treatment layer. An anodized film by barrier type anodizing treatment is formed on the substrate, and an etching treatment layer is formed on the cathode foil by etching treatment which is a surface expansion treatment. In the present embodiment, both the anode foil 1 and the cathode foil are made of aluminum, and the anode foil 1 has a thickness of 0.1 mm and the cathode foil has a thickness of 0.05 mm.

  The lead terminal 2 is a strip-shaped body made of aluminum and having a thickness of 0.2 mm on which no etching treatment layer or oxide film is formed.

  The lead-out terminal 2 is overlaid on the anode foil 1, the anode foil 1 side of the overlapped portion is placed on a processing board, and is pressed from above the lead-out terminal 2 by pressing means (not shown). The caulking portion 6 is formed to be in a temporarily joined state (see FIG. 1). And these crimped parts 6 are temporarily joined with the anode foil 1 and the lead terminal 2 more firmly fixed by performing ultrasonic welding, cold weld, arc welding or the like as necessary. It is said.

  Then, the leading end of the star rod 4 that rotates from the back side of the lead terminal 2 in the crimping portion 6 between the anode foil 1 and the lead terminal 2 is fixed by fixing means (not shown) with the lead terminal 2 and the anode foil 1. The probe 5 provided in the pipe is press-fitted to a predetermined depth, and the press-fitted probe 5 is moved along the joining line shown in FIG. 3 is formed, and the anode foil 1 and the lead terminal 2 are joined electrically and mechanically. Similarly, the lead terminal 2 and the cathode foil are connected by friction stir welding. In addition, you may perform friction stir welding from the anode foil 1 side in the crimping part 6. FIG.

  In this friction stir welding, when the press-fitted probe 5 rotates, friction heat and processing heat are generated between the lead terminal 2 and the electrode foil, and the lead terminal 2 and electrode foil are constituted by the friction heat and processing heat. The aluminum that is the metal to be heated is heated and softened, and the softened aluminum is agitated by the rotation of the probe 5, so that the oxide film present on the surface of the electrode foil is destroyed, so It comes into contact in a softened state, and solidifies behind it as the probe 5 moves, so that the lead-out terminal 2 and the electrode foil are firmly solid-phase connected.

  In these friction stir welding, it is preferable to provide an inclination angle θ of 2 to 5 degrees so that the probe 5 precedes the star rod 4. The thickness of the electrode foil and the number of rotations of the star rod 4 and the amount of press-fitting may be selected as appropriate.

  Further, the shape of the probe 5 and the like may be appropriately selected from the thickness of the lead terminal 2 to be used, the number of electrode foils, the rotation speed of the star rod 4, the amount of press-fitting, and the like.

  Further, the number of rotations of the star rod 4, the amount by which the probe 5 is press-fitted, the moving speed, and the like may be appropriately selected from the thickness of the extraction terminal 2 to be used, the number of electrode foils, and the like.

  Thereafter, the anode foil 1 and the cathode foil to which the lead terminal 2 is connected by friction stir welding are wound with a separator made of electrolytic paper such as manila paper or kraft paper interposed therebetween as an electrically insulating separator, so that the capacitor element is wound. It is formed. The lead terminal 2 for anode and cathode led out from this capacitor element is connected to an external terminal provided through a sealing member made of insulating resin or the like and integrated with the sealing member. Is impregnated with a driving electrolyte solution and stored in a bottomed cylindrical outer case made of aluminum or the like. The sealing member is fitted into the opening of the outer case, and the electrolytic capacitor is completed by sealing the opening end of the outer case by curling.

  The capacitor element is formed by winding. However, the present invention is not limited to this, and each lead-out terminal 2 is connected to each other via a separator between the anode foil 1 and the cathode foil each having the lead-out terminal 2 connected by friction stir welding. A capacitor element may be formed by stacking so as not to contact each other.

  As described above, according to the present embodiment, the state of the cross-section of the connecting portion 3 that has been friction stir welded is that aluminum softened by frictional heat and processing heat is stirred and the aluminum ingots come into contact with each other and solidify. In contrast, the solid phase without a boundary is formed and the bonding strength is high, whereas the state of the cross-section of the connecting portion 3 by conventional ultrasonic welding is that the interface of each aluminum foil remains, Since the bonding strength at this interface is also extremely unstable, even if the surface of the electrode foil that is the connection portion 3 has an etching treatment layer or an oxide film layer as in this embodiment, these etching treatments are performed. Because the layer and the oxide film layer are destroyed by the rotation of the probe 5 in the friction stir welding, and the aluminum that is the base metal melts and becomes integrated, regardless of the presence or absence of the etching treatment layer or the chemical conversion film layer, Said It is possible to obtain a good connection between the electrode foil and the lead terminal 2. In addition, by performing friction stir welding in a temporarily joined state having almost no gap between the electrode foil and the lead terminal 2, it is possible to greatly reduce the occurrence of weld defects such as voids in the connection portion 3. Thus, a more stable and good electrical and mechanical connection state can be obtained.

  As mentioned above, although this invention was demonstrated based on Example 1, this invention is not limited to these Examples, Even if there is a change and addition in the range which does not deviate from the main point of this invention, it is in this invention. Needless to say, it is included.

  For example, in the embodiment, the extraction terminal 2 is overlapped on the electrode foil and the friction stir welding is performed. However, the present invention is not limited to this, and as shown in FIGS. 2 is folded, and an electrode foil is interposed between the two, that is, the electrode foil is sandwiched between the lead terminals 2 to prevent displacement of the electrode foil, and friction stir welding is performed from the back of the lead terminals 2 sandwiching the electrode foil. May be implemented. The probe 5 is desirably press-fitted to the lead-out terminal 2 arranged on the lower side, and in this way, the lead-out terminals 2 arranged on the upper and lower surfaces of the electrode foil are joined together. Will improve.

  In addition to this, as shown in FIGS. 3A and 3B, a reinforcing base material made of aluminum or the like on the lower surface side of the electrode foil overlapping the lead terminal 2 or on the upper surface side of the lead terminal 2. 7 may be used to perform friction stir welding. A part of the reinforcing substrate 7 is connected to the electrode foil by friction stir welding, so that the connection between the electrode foil and the lead terminal 2 is strengthened. In this case, friction stir welding can also be performed from the reinforcing base material 7 side, which prevents the terminal function from being deteriorated due to deformation or fracture of the lead terminal 2 due to rotation of the probe 5. If the reinforcing base material 7 is also temporarily joined by caulking or the like, there is no gap between the reinforcing base material 7 and the electrode foil, and defects generated during connection can be reduced.

  In the embodiment, the electrode foil and the lead-out terminal 2 are connected by press-fitting and moving the probe 5 as friction stir welding, but the probe 5 is press-fitted as shown in FIG. It is also possible to perform welding after pulling out after rotating for a time. In this case, a plurality of locations may be connected.

  Further, as the thickness of the reinforcing base material 7, when the thickness is 0.2 mm or less, the strength as the reinforcing base material 7 cannot be obtained, and the probe 5 is press-fitted from the back surface of the reinforcing base material 7. When the friction stir welding is performed, it is difficult to control the rotation speed, moving speed, angle, and the like of the star rod 4, and stable friction stir welding becomes difficult. Therefore, the thickness is preferably in the range of 0.2 mm to 1.0 mm.

  Moreover, although the strip | belt-shaped body which consists of aluminum etc. was illustrated as an extraction terminal 2 in the Example, it is not restricted to this, It applies to the extraction terminal 2 which consists of an aluminum material which has the round bar part and flat part which welded CP wire. Needless to say.

  In the above embodiment, a normal multilayer electrolytic capacitor has been described as an example. However, the present invention is not limited to this, and the anode foil 17 and the cathode foil 8 are provided with activated carbon sheets on both sides of an aluminum foil. Needless to say, the present invention can be applied to the connection between the anode foil 1 and the cathode foil and the lead-out terminal 2 in the electric double layer capacitor having a polarizable electrode foil.

It is sectional drawing and a perspective view which show the connection state of the capacitor | condenser in the Example of this invention. It is sectional drawing and a perspective view which show the connection state of the capacitor | condenser in the other Example of this invention. It is sectional drawing and a perspective view which show the connection state of the capacitor | condenser in the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anode foil 2 Lead terminal 3 Connection part 4 Star rod 5 Probe 6 Clamping part 7 Reinforcement base material

Claims (7)

A capacitor in which a lead-out terminal is electrically and mechanically connected to an electrode foil by friction stir welding, and a capacitor element formed by laminating or winding the electrode foil is housed in an outer case.
The capacitor according to claim 1, wherein the lead-out terminal is folded and the electrode foil is disposed therebetween. The capacitor according to claim 1 or 2, wherein a reinforcing base is disposed on at least a part of the lead terminal or the electrode foil, and a part of the reinforcing base is connected to the electrode foil by friction stir welding. A lead-out terminal is connected to the electrode foil, and a capacitor element is formed by laminating or winding between the electrode foils via a separator, and the capacitor element is housed in an outer case, and the opening end of the outer case is sealed by a sealing member. In the manufacturing method of the capacitor formed by sealing, a reinforcing base material is disposed on at least a part of the connection portion between the electrode foil and the lead terminal, and the lead terminal is electrically and mechanically connected to the electrode foil by friction stir welding. To manufacture a capacitor. The method for manufacturing a capacitor according to claim 4, wherein a frictional welding is performed in a temporarily joined state having substantially no gap between the electrode foil and the lead terminal. The method for manufacturing a capacitor according to claim 5, wherein the method of setting the temporarily bonded state includes caulking by pressurizing the electrode foil and the lead terminal. The method for manufacturing a capacitor according to claim 5 or 6, wherein the method of setting the temporary bonding includes ultrasonic welding, cold weld, and arc welding.

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