JP2008091562A - Electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor capable of controlling the shape of the connection section between electrode foil and a lead-out terminal, and connecting the electrode foil and the lead-out terminal reliably with low resistance. <P>SOLUTION: In the electrolytic capacitor, the lead-out terminal is connected to the electrode foil by overlapping the lead-out terminal to the electrode foil, piercing a stitch needle having a polygonal tip section from the side of the lead-out terminal, forming a polygonal through hole on the lead-out terminal and the electrode foil, and pressure-welding the return section of the lead-out terminal formed at the side of the electrode foil, and the electrode foil. In the electrolytic capacitor, a non-oxide film section is formed at one portion of the surface of the electrode foil for providing a boundary between an oxide film section and the non-oxide film section, and the apex of the polygonal through hole formed on the lead-out terminal and the electrode foil is arranged near the boundary. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a connection structure between an electrode foil and a lead terminal in an electrolytic capacitor.

  In an electrolytic capacitor, there are an anode foil with an etching process and an oxide film formed on the surface as an electrode foil, and a cathode foil with an etching process on the surface, and an aluminum wire having a flat portion of a predetermined length as a lead terminal. There are welded CP wires and thin flat tab terminals, etc. These lead terminals are connected to the anode foil and cathode foil, and a separator made of insulating paper or the like is interposed between the anode foil and cathode foil. Then, the capacitor element is formed by winding or stacking. This capacitor element is housed in the outer case together with the driving electrolyte, and the opening is sealed with a sealing member to complete the electrolytic capacitor.

  Conventionally, as a method for connecting the electrode foil and the lead terminal, the lead terminal is superimposed on the electrode foil, and the connection is performed by stitching, cold welding, ultrasonic welding, or the like. As a method for improving the mechanical strength and electrical reliability in the connection between the electrode foil and the lead terminal, an oxide film formed on the electrode foil is removed, and the lead terminal is connected to the removed portion by stitching. (Patent Document 1 and Patent Document 2).

Japanese Utility Model Publication No. 54-164451 Japanese Patent Laid-Open No. 02-222517

  However, the conventional connection method cannot satisfy the electrical reliability. That is, as in the past, by removing the oxide film formed on the surface of the electrode foil, the aluminum that becomes the core metal of the electrode foil is exposed, and the exposed portion and the lead terminal are connected by stitching, thereby oxidizing the The connection can be made with a lower resistance than the connection without removing the film, but the resistance of the connection may not be satisfied depending on the removed shape of the oxide film. For example, as shown in FIG. 4A, when the oxide film removal portion 13 is smaller than the shape of the through-hole 14 formed when the stitch needle is pierced, the oxide film is harder than aluminum. The oxide film that has not been removed from the periphery obstructs the formation of the electrode foil 12 and the return portion of the lead terminal 11 into an appropriate shape by the stitch needle. Also, as shown in FIG. 4B, when the oxide film removal portion 13 is larger than the shape of the through hole 14 when the stitch needle is pierced, the aluminum cored bar is soft and easily torn, so the stitch needle It is difficult to form the through-hole 14 that fits the cross-sectional shape of the stitch needle when the needle is pierced, and the mechanical strength of the connecting portion is low.

  Therefore, the present invention solves the conventional problems, enables the shape of the connection portion between the electrode foil and the lead terminal to be controlled, and enables the connection between the electrode foil and the lead terminal with low resistance and high reliability. The object is to provide an electrolytic capacitor.

In order to achieve the above object, the present inventor has intensively studied, and as a result, the removal shape of the non-oxide film formed so as not to have the oxide film of the electrode foil, the shape of the through-hole formed by the stitch needle, and the arrangement thereof It was found that by specifying the position, a stable connection portion shape can be formed, and a low-resistance and high-reliability connection is possible. Therefore, the electrolytic capacitor of the present invention has a lead terminal overlapped with the electrode foil, a stitch needle having a polygonal cross section at the tip is pierced from the lead terminal side, and a polygonal through hole is formed in the lead terminal and the electrode foil. In the electrolytic capacitor in which the lead terminal and the electrode foil are connected by press-contacting the lead terminal formed on the foil side and the return portion of the electrode foil,
A non-oxide film part is formed on a part of the surface of the electrode foil to provide a boundary between the oxide film part and the non-oxide film part, and the apex of the polygonal through-hole formed in the lead terminal and the electrode foil is near this boundary. It is characterized by having been arranged in.
According to this, each vertex of the polygonal through hole formed in the lead terminal and the electrode foil by the stitch needle having a polygonal cross section at the tip is arranged in the vicinity of the boundary between the oxide film part and the non-oxide film part. The return portion of the lead terminal and the electrode foil is formed with the boundary between the oxide film portion and the non-oxide film portion as the base point when the stitch needle is pierced. The return part can be controlled, and by appropriately setting the shape of the non-oxide film, the return part of the lead terminal can be formed in an appropriate shape, and a low resistance and highly reliable connection part can be formed. It becomes.

Further, the outer peripheral shape of the polygonal through-hole formed in the lead terminal and the electrode foil is made to coincide with the boundary with the non-oxide film portion.
According to this, by making the outer peripheral shape of the polygonal through-hole and the shape of the entire circumference of the boundary between the oxide film portion and the non-oxide film portion into substantially the same shape, the stitch needle is used as the lead terminal and the electrode foil. When pierced, the entire boundary of the non-oxide film portion functions as a base point, so that the lead terminal and the return portion of the electrode foil can be formed with higher accuracy.

  Further, the non-oxide film portion of the electrode foil is characterized in that it is provided on at least the surface on which the lead terminals are superimposed. According to this, since the oxide film does not exist on the surface of the electrode foil serving as the connection surface with the lead-out terminal, it is possible to connect with low resistance and high reliability.

  As described above, according to the present invention, by arranging the shape of the through-hole formed by the boundary between the oxide film portion and the non-oxide film portion of the electrode foil and the stitch needle in an appropriate shape and an appropriate position, The lead terminals and the return portions of the electrode foils for stitch connection can be formed with high accuracy, and the connection between the lead terminals and the electrode foils with low resistance and high reliability can be realized.

  Embodiments of the present invention will be described below with reference to the drawings. 1A shows the electrode foil and the lead terminal in the electrolytic capacitor according to the embodiment of the present invention, and FIG. 1B shows the shape of the stitch needle. FIGS. 2A to 2C show a connection process between the electrode foil and the lead terminal of the electrolytic capacitor according to the embodiment of the present invention. FIG. 3 shows an arrangement position of the electrode foil, the lead terminal, and the stitch needle of the electrolytic capacitor according to the embodiment of the present invention.

  The electrolytic capacitor includes an outer case in which a capacitor element is enclosed, and an opening of the outer case is sealed by a sealing member made of elastic rubber having a through portion through which the lead terminal 1 is inserted.

  The lead terminal 1 is formed by pressing a part of a rod-shaped member made of aluminum, forming a flat portion and a round bar portion, and welding a CP wire made of a wire to the round bar portion. A flat tab terminal may be used as the lead terminal. The lead terminal 1 is composed mainly of the same material as the electrode foil 2 such as aluminum, an anode foil having an etching layer and an oxide film layer formed thereon, and a cathode having an etching layer formed on the surface. Connected to each of the foils. Note that the CP wire is copper-plated on the steel wire, and further tin-plated or solder-plated as necessary.

A method for connecting the lead terminal 1 and each electrode foil 2 will be described below. First, the flat portion of the lead terminal 1 is disposed so as to overlap the electrode foil 2, and then the through-hole 8 is formed by piercing the stitch needle 6 having a square tip section from the flat portion side of the lead terminal 1.
Here, as shown in FIG. 1A, a non-oxide film portion 3 having no oxide film is formed on both surfaces of the electrode foil 2 to be a connection portion with the lead terminal 1, and the oxide film portion and The boundary 4 is provided. The non-oxidized film part 3 may be formed in advance so that an oxide film is not formed during the oxide film formation process by masking or the like, or press, grinding, cutting, ultrasonic vibration, laser irradiation, arc irradiation, acid or alkali It is formed by removing the oxide film by chemical treatment or the like.
The boundary 4 between the oxide film portion and the non-oxide film portion 3 is a through-hole 8 formed when the lead terminal 1 is overlapped with the electrode foil 2 and the stitch needle 6 having a square tip section is pierced into the electrode foil 2. The shape is such that at least the vertex 5 is arranged in the vicinity of the boundary 4. That is, since the lead terminal 1 and the through hole 8 of the electrode foil 2 formed by the stitch needle 6 having a square front end cross section shown in FIG. 1B are square and substantially the same as the cross-sectional shape of the stitch needle 6, this stitch By forming the non-oxide film portion 3 so as to be substantially the same as the cross-sectional shape of the needle 6, the vertex 5 of the through-hole 8 is arranged in the vicinity of the boundary 4 of the non-oxide film portion 3. In the present invention, the apex 5 of the through-hole 8 by the stitch needle 6 may be disposed in the vicinity of the boundary 4 of the non-oxide film portion 3, and the non-oxide film portion 3 is made circular as shown in FIG. It may be formed. In the present invention, the stitch needle 6 has a quadrilateral tip cross section, but a hexagon or octagon can be used, and each polygon is preferably a regular polygon.

  Next, as shown in FIG. 2 (a), the lead terminal 1 is arranged so as to overlap the electrode foil 2 on which the non-oxide film portion 3 is formed, and the stitch needle 6 having a polygonal cross-section at the tip is provided from the lead terminal side. When the apex 5 of the cross section of the needle 6 and the apex 5 of the boundary 4 between the oxide film portion and the non-oxide film portion 3 are punctured, the electrode foil 2 and the lead terminal 1 are connected to the stitch needle 6. While being torn and penetrated in four directions by a polygonal cross-section, the electrode foil is disposed on the electrode foil side from the vicinity of the boundary (vertex 5 and its side) between the oxide film portion and the non-oxide film portion 3 of the electrode foil 2. 2 and the return portion 7 of the lead terminal 1 are formed. Next, as shown in FIG. 2B, the stitch needle 6 is extracted from the flat portions of the electrode foil 2 and the lead terminal 1, and the electrode foil 2 and the lead terminal 1 are separated by a press plate made of a pair of metal (not shown). The electrode foil 2 and the return portion 7 of the lead terminal 1 are crushed by pressing from above and below, and the electrode foil 2 and the lead terminal 1 are connected by this return portion 7.

  In this way, the non-oxide film portion 3 is formed on a part of the surface of the electrode foil 2 to provide the boundary 4 between the oxide film portion and the non-oxide film portion 3, and the polygon formed on the lead terminal 1 and the electrode foil 2. By connecting the apex 5 of the through-hole 8 in the vicinity of the boundary 4 and stitch-connecting, as shown in FIG. 2C, the through-hole 8 having substantially the same cross-sectional shape as the stitch needle 6 is formed. Since the electrode foil 2 and the return portion 7 of the lead-out terminal 1 are formed uniformly in four directions, a highly reliable connection is possible.

  Next, the electrode foil 2 to which the lead terminal 1 is connected is wound or laminated via a separator to form a capacitor element. The capacitor element is housed in an outer case made of aluminum together with a driving electrolyte, and an opening member of the outer case is provided with a sealing member made of elastic rubber having a through portion through which the lead terminal 1 is inserted. The electrolytic capacitor is completed by caulking and sealing the opening by curling.

(A) shows the electrode foil and the lead terminal in the electrolytic capacitor according to the embodiment of the present invention, and (b) in FIG. 1 shows the shape of the stitch needle. (A) to (c) shows the connection process between the electrode foil and the lead terminal of the electrolytic capacitor according to the embodiment of the present invention. The arrangement | positioning position with the electrode foil of the electrolytic capacitor which concerns on the Example of this invention, an extraction terminal, and a stitch needle is shown. The arrangement positions of the electrode foil, the lead terminal, and the stitch needle of the conventional electrolytic capacitor are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lead terminal 2 Electrode foil 3 Non-oxide film part 4 Boundary 5 Vertex 6 Stitch needle 7 Return part 8 Through hole 11 Lead terminal 12 Electrode foil 13 Removal part 14 Vertex 15 Through hole

Claims (3)

A lead terminal is overlaid on the electrode foil, and a stitch needle having a polygonal cross section at the tip is pierced from the lead terminal side, a polygonal through hole is formed in the lead terminal and the electrode foil, and a lead terminal formed on the electrode foil side and In the electrolytic capacitor in which the lead terminal and the electrode foil are connected by pressing the return portion of the electrode foil,
A non-oxide film part is formed on a part of the surface of the electrode foil to provide a boundary between the oxide film part and the non-oxide film part, and the apex of the polygonal through-hole formed in the lead terminal and the electrode foil is near this boundary. Electrolytic capacitor placed in   The electrolytic capacitor according to claim 1, wherein an outer peripheral shape of a polygonal through-hole formed in the lead terminal and the electrode foil is matched with a boundary between the oxide film portion and the non-oxide film portion. 4. The electrolytic capacitor according to claim 1, wherein the non-oxide film portion of the electrode foil is provided on at least a surface on which the lead terminals are superimposed.

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