JPH069181B2 - Method for manufacturing lead terminal for electric double layer capacitor - Google Patents

Description

The present invention relates to a method for manufacturing a lead terminal for an electric double layer capacitor.

[Conventional technology]

An electric double layer capacitor has a case body with a shallow dish shape and a cap to be covered with a polarizable electrode. Each polarizable electrode is impregnated with a predetermined electrolytic solution, and a separator is placed between them. And a coin-shaped capacitor cell in which the case body and the cap are united together.

This capacitor cell is mainly used as a backup power source for a memory and the like, and a desired voltage can be obtained by stacking a plurality of such cells, but the capacitor cell itself does not have an external terminal. Therefore, when mounting on a circuit board or the like, a predetermined number of capacitor cells are laminated, and lead terminals are attached to the exposed anode and cathode surfaces by, for example, welding.

The case of the capacitor cell is usually made of stainless steel, and if the welding is not made of the same metal, the adhesion will be poor, so that the lead terminal is also made of stainless steel. However, since stainless steel has poor solderability, if the entire lead terminal is pre-soldered in consideration of the fact that it is mounted on a circuit board and then soldered, the solder with a low melting point will be obstructed during welding. And welding becomes difficult.

Therefore, conventionally, the solder plating is thinned so that it has almost no effect on welding, or the tip of the lead terminal (mounting leg portion to the circuit board) is partially plated.

[Problems to be Solved by the Invention]

However, if the solder plating is thin as in the former case, the solderability after mounting on the board will deteriorate. On the other hand, in the latter case of partial plating, since this type of solder plating is usually performed by dipping, it is necessary to isolate the welded part of the lead terminal from the plating solution by taping or the like to prevent plating. However, the number of man-hours is extra and the cost is increased.

[Means for Solving the Problems]

In order to solve the above problems, in the present invention, a stainless steel lead terminal, which is attached by welding to an electrode surface of a stainless steel case of an electric double layer capacitor, is immersed in a plating bath to form solder plating on the entire surface. After that, at least the solder plating of the welded portion of the case with respect to the electrode surface is removed. In this case, the solder plating is removed by heating, laser irradiation or mechanical polishing.

[Work]

As mentioned above, since the solder plating is removed from the welded part of the lead terminal, it is possible to firmly attach this lead terminal by welding, but at the time of manufacturing it, dip the whole in a plating bath and solder After applying
Since the solder plating on the welded portion is removed, it does not require as much labor as partial plating, and the plating thickness can be increased.

〔Example〕

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

1 and 2 show, for example, an electric double layer capacitor 1 in which two coin-shaped capacitor cells 2 and 3 are laminated. That is, according to this embodiment, a dish-shaped holder 4 made of a metal such as stainless steel is fixed to, for example, the anode surface 2a side of one of the capacitor cells 2 by welding, and the cathode of the other capacitor cell 3 is attached to the holder 4. The surface 3b side is fitted, in which case the cathode surface 3b and the holder 4 are welded at several points. Then, an electrically insulating sleeve made of a heat-shrinkable resin is covered around this capacitor cell laminated body, and the cathode surface 2b of one capacitor cell 2 and the anode surface of the other capacitor cell 3 exposed to the outside thereof. Lead terminals 6 and 7 are attached to 3a by welding or the like.

Referring also to FIG. 3, in this embodiment, the lead terminals 6 and 7 are each formed of a round bar made of stainless steel having a predetermined diameter and having one end side crushed into a flat plate shape by a press or the like. The welded portions 6a and 7a with respect to the electrode surfaces 2b and 3a, and the remaining round bar portion serve as mounting legs 6b and 7b with respect to a circuit board (not shown). In this case, the lead terminals 6 and 7 have welded portions 6a and 7a, respectively.
The portions other than the welding surfaces 6a 'and 7a' for the electrode surfaces 2b and 3a are solder-plated as shown by the dotted lines. Therefore, according to this, the stainless steels are abutted against each other, so that the welding can be performed well.

In order to obtain such lead terminals 6 and 7, in the present invention, first, a stainless steel round bar is pressed to form welded portions 6a and 7a at one end thereof, and the welded portion is immersed in a solder bath (not shown) (dipping). ) And solder plating is applied over the entire surface thereof, that is, the welded portions 6a, 7a and the mounting legs 6b, 7b. After that, the welding surface 6 of the welding portions 6a, 7a to the electrode surface of the coin cell
The solder plating formed on the portions a'and 7a 'is removed. Examples of the method include heating with a gas burner, heating with laser irradiation, and mechanical polishing. In this example, the welded parts 6a, 7
welding surface 6a ', 7a' to the electrode surface of the coin cell of FIG.
Although only the solder plating is removed, the mounting direction is limited at the time of welding, so that the solder plating of the mounting legs 6b, 7b is left and the front and back surfaces of the welded portions 6a, 7a are not removed. The solder plating may be removed. Further, as shown in FIG. 4, the lead terminals 6 and 7 may be stamped from a stainless steel plate. Further, the present invention can be applied to a lead terminal used for a horizontal mounting type electric double layer capacitor mounted such that an electrode surface is parallel to a mounting surface of a circuit board.

〔The invention's effect〕

As described above, according to the present invention, in order to obtain the same stainless steel lead terminal that is attached to the electrode surface of the stainless steel case by welding, the lead terminal is dipped in the plating bath and soldered on the entire surface. After plating, the solder plating on the welded part is removed so that it does not take time like partial plating that requires taping etc., and the plating can be thickly attached to the mounting legs for the circuit board. Effects such as, are produced.

[Brief description of drawings]

Each of the drawings relates to an embodiment of the present invention. FIG. 1 is a perspective view showing the capacitor cell laminate and each lead terminal separately, FIG. 2 is a side sectional view of the embodiment, and FIG. Is a perspective view showing a lead terminal according to the same embodiment, and FIG. 4 is a perspective view showing a lead terminal according to another embodiment. In the figure, 1 is an electric double layer capacitor, 2 and 3 are capacitor cells, 4 is a holder, 5 is a sleeve, 6 and 7 are lead terminals, 6a and 7a are welded portions, 6a 'and 7a' are welded surfaces,
6b and 7b are mounting legs.

Claims (4)

[Claims] 1. A method for manufacturing a stainless steel lead terminal, which is attached by welding to each electrode surface of a capacitor cell in which a capacitor element is housed in a coin-shaped (or button-shaped) stainless case, wherein the lead terminal is After forming the solder plating on the entire surface of
A method of manufacturing a lead terminal for an electric double layer capacitor, characterized in that at least a welded portion of a welded portion to the electrode surface of the capacitor cell is removed. 2. The method for manufacturing a lead terminal for an electric double layer capacitor according to claim 1, wherein the removal of the solder plating is performed by a heating means. 3. The method for manufacturing a lead terminal for an electric double layer capacitor according to claim 1, wherein the removal of the solder plating is performed by laser irradiation. 4. The method for producing a lead terminal for an electric double layer capacitor according to claim 1, wherein the removal of the solder plating is performed by mechanical polishing means.