JP2000124073A - Aluminum electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent whiskers from growing by using a capacitor element, having an outer lead wire having a specified Sn-plated Cu-coated steel wire bonded to one end of an Al wire connected to an electrode foil. SOLUTION: A lead wire 3 has a Cu-coated steel wire 2, plated with 100% Sn which is bonded to one end of an Al wire 1. An electrode foil, to which one end of the Al wire 1 is connected, is used to constitute a capacitor element. The capacitor element is housed, together with a driving electrolyte soln., in a bottom-closed tubular metal case and has a through-hole for passing the lead wire 3. The opening of the metal case is sealed with a sealing member. The Al wire 1 of the lead wire 3 is bonded to the coated steel wire 2, by inserting one end of the steel wire 2 into a recess 1a formed at one end of the Al wire 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum electrolytic capacitor used for various electronic devices and the like, and more particularly to a global environment-friendly capacitor which does not use lead, which is one of the substances which have recently been receiving attention and which has an adverse effect on the environment. It relates to a reliable aluminum electrolytic capacitor.

[0002]

2. Description of the Related Art A conventional aluminum electrolytic capacitor of this type will be described with reference to the drawings.

FIG. 3 is a cross-sectional view showing a conventional aluminum electrolytic capacitor. In FIG.
Is a pair of lead wires for external connection pulled out from the capacitor element 6 in a pair, 8 is a bottomed cylindrical metal case containing the capacitor element 6 together with a not-shown driving electrolyte, and 9 is the pair of lead wires. 7 is a sealing member provided with a through hole through which the opening of the metal case 8 is sealed.

FIG. 4 is a perspective view showing the lead wire 7. In FIG. 4, reference numeral 10 denotes an aluminum wire, and 11 denotes a lead-containing tin-plated copper-coated steel connected to one end of the aluminum wire 10 by arc welding. A wire 12 is an alloy portion formed at a connection portion between the lead-containing tin-plated copper-coated steel wire 11 and the aluminum wire 10. A flat portion 10a is provided at one end of the aluminum wire 10. 10a is connected to an electrode foil (not shown) constituting the capacitor element 6.

FIG. 5 shows the above-described lead-containing tin-plated copper-coated steel wire 11.
FIG. 2 is a cross-sectional view showing a configuration of the present invention, in which a steel wire made of iron (Fe) is coated with copper (Cu) by plating or the like, and the outer surface thereof is plated with tin (Sn + Pb) containing about 5% lead. It is composed.

As described above, the conventional aluminum electrolytic capacitor is configured by using the lead wire 7 using the lead-containing tin-plated copper-coated steel wire 11 shown in FIGS. 4 and 5, but it has a problem of recent environmental pollution. Therefore, there is a growing need in the market for an aluminum electrolytic capacitor using a lead wire that does not use lead.
An aluminum electrolytic capacitor using a lead wire using a tin-plated copper-coated steel wire of 00% has also been put to practical use.

[0007]

However, in an aluminum electrolytic capacitor using a lead wire that does not use lead, as shown in FIG. 6, a connecting portion between an aluminum wire 13 and a tin-plated copper-coated steel wire 14 is used. A whisker 16 of tin is generated from the alloy part 15 generated in the above, and the occurrence of the whisker 16 may cause a short circuit between a pair of lead wires (terminals) in the worst case. there were.

The present invention solves such a conventional problem,
It is an object of the present invention to provide a highly reliable aluminum electrolytic capacitor that does not generate whiskers even when a lead wire that does not use lead is used.

[0009]

In order to solve the above-mentioned problems, an aluminum electrolytic capacitor according to the present invention is an external lead in which a tin-plated copper-coated steel wire in which one end of an aluminum wire is tin-plated with 100% tin is joined. An aluminum electrolytic capacitor is formed by using a capacitor element formed by connecting the aluminum wire side of a lead wire to an electrode foil.

According to the present invention, since lead is not used, it is friendly to the global environment, and whiskers are not generated. Therefore, a highly reliable aluminum electrolytic capacitor can be realized.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to an aluminum wire as a lead wire in which one end of an aluminum wire is joined to a tin-plated copper-coated steel wire in which tin plating made of 100% tin is applied. A capacitor element configured using an electrode foil connected to the side, a metal case having a bottomed cylindrical shape for accommodating the capacitor element together with a driving electrolyte, and a through hole through which the lead-out lead wire passes; This is a configuration including a sealing member for sealing the opening of the case, and has an effect that an aluminum electrolytic capacitor that is environmentally friendly can be provided because lead is not used.

According to a second aspect of the present invention, in the first aspect of the present invention, the connection between the aluminum wire of the lead wire and the tin-plated copper-coated steel wire is performed by tin-plating a recess provided at one end of the aluminum wire. Whisker is generated because the alloy part formed at the connection between the aluminum wire and the tin-plated copper-coated steel wire is not exposed on the outer surface. And an effect that a highly reliable aluminum electrolytic capacitor can be provided.

According to a third aspect of the present invention, in the second aspect, a diffusion alloy layer of copper, tin and aluminum is formed at a joint between the aluminum wire and the tin-plated copper-coated steel wire. This alloy layer has the effect of greatly improving the bonding strength and improving the bonding reliability.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a lead wire 3 of the aluminum electrolytic capacitor according to the embodiment, in which 1 is an aluminum wire, 1a is a concave portion provided at one end of the aluminum wire 1, and 1b is an aluminum wire. This is a flattened portion provided on the other end of the wire 1, and the flattened portion 1b is connected to an electrode foil (not shown) constituting the capacitor element 6 (shown in FIG. 3). Numeral 2 is a tin-plated copper-coated steel wire made of 100% tin and subjected to tin plating.

Next, a description will be given of a method of manufacturing the lead wire 3 configured as described above. First, the tin-plated copper-coated steel wire 2 is provided in the recess 1a of the aluminum wire 1 having the recess 1a at one end. One end is inserted and joined, and the other end of the aluminum wire 1 is provided with a flattened portion 1b. Regarding this joining, first, a method in which a recess 1a having a diameter slightly larger than the outer diameter of the tin-plated copper-coated steel wire 2 is provided at one end of the aluminum wire 1 and joined using a conductive adhesive, A method in which a concave portion 1a having a diameter slightly smaller than the outer diameter of the coated steel wire is provided at one end of the aluminum wire 1 and mechanically joined by a press-fitting method. Third, a concave portion of the aluminum wire 1 before and after the press-fitting in the second method. There is a method in which the vicinity of 1a is heated to form an alloy layer of tin plating of the tin-plated copper-coated steel wire 2 and the aluminum wire 1. In the present embodiment, the third method having the highest reliability of the bonding strength is used. (A method of forming an alloy layer by heating).

FIG. 2 is a perspective view of a capacitor element 5 showing another embodiment, in which a tin-plated copper-coated steel wire 2a made of 100% tin and plated with tin is used as a lead wire of a conventional example. Thus, the capacitor element 5 is formed using the lead wire 4 joined to one end of the aluminum wire 1c by arc welding and subjected to a bending process. The capacitor element 5 shown in FIG. 2 is used as a comparative example. Figure 1 above
Table 1 shows the results of comparison of the whisker generation status with the capacitor element 6 configured using the lead wire 3 of the present embodiment shown in FIG.

[0017]

[Table 1]

It is generally said that whiskers are generated due to stress or heat during processing, but the lead wire 3 of the present embodiment has no whiskers as apparent from the above (Table 1). The same stable result was obtained even after 500 hours and 1000 hours. However, in the comparative example, although whiskers did not occur at the time when the lead wire 4 was formed, 500 hours
Whiskers are generated as the time elapses from 1000 hours, indicating that the effect of the present invention is remarkably exhibited.

[0019]

As described above, the aluminum electrolytic capacitor according to the present invention has the above-mentioned aluminum wire side of an external lead wire in which one end of an aluminum wire is connected to a tin-plated copper-coated steel wire in which tin plating made of 100% tin is applied. Is connected to the electrode foil to form an aluminum electrolytic capacitor, so that the alloy layer generated at the junction between the tin plating of the tin-plated copper-coated steel wire and the aluminum wire draws out the lead wire. Since it is not exposed to the outside, no whiskers are generated, and an environment-friendly aluminum electrolytic capacitor is realized by using a tin-plated tin-plated copper-coated steel wire made of 100% tin and using no lead. Is what you can do.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external lead wire of an aluminum electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a capacitor element according to the embodiment.

FIG. 3 is a sectional view of a conventional aluminum electrolytic capacitor including an embodiment of the present invention.

FIG. 4 is a perspective view showing a conventional lead wire.

FIG. 5 is a sectional view showing the configuration of the lead wire of FIG. 4;

FIG. 6 is a perspective view of a main part of a lead wire showing a whisker generation state of a conventional product

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum wire 1a Depression 1b Flat processing part 2 Tin-plated copper-coated steel wire 3, 4 Lead wire 5 Capacitor element

Claims (3)

[Claims] 1. A capacitor element formed by using an electrode foil connected to the aluminum wire side of a lead wire in which a tin-plated copper-coated steel wire in which tin plating made of 100% tin is applied to one end of an aluminum wire. And an aluminum electrolytic comprising a bottomed cylindrical metal case for accommodating the capacitor element together with the driving electrolyte, and a sealing member provided with a through hole through which the lead-out lead wire passes to seal the opening of the metal case. Capacitors. 2. An aluminum wire of a lead wire and a tin-plated copper-coated steel wire are joined by inserting a tin-plated copper-coated steel wire into a recess provided at one end of the aluminum wire. 2. The aluminum electrolytic capacitor according to 1. 3. A diffusion alloy layer of copper, tin and aluminum is formed at a joint between an aluminum wire and a tin-plated copper-coated steel wire.
The aluminum electrolytic capacitor described in 1.