JPS6017900Y2 - Electrolytic capacitor - Google Patents

Description

[Detailed Description of the Invention] This invention relates to improvement of electrolytic capacitors, mainly solid electrolytic capacitors.

In general, this type of solid electrolytic capacitor is made of a capacitor element A made by press-molding metal powder having a valve action such as tantalum, niobium, aluminum, etc. into a cylindrical shape and sintering it, as shown in Fig. 1. A metal wire having a valve action is planted as an anode lead B, and a first external lead member C is welded to the protruding portion of this anode lead B.
The second external lead member is soldered to the electrode lead layer E formed on the circumferential surface of the capacitor element A through an oxide layer and a semiconductor layer, and then the main part including the capacitor element A is soldered to the resin material F. It is covered with

By the way, when assembling the capacitor element A in this capacitor, for example, as shown in FIG. 2, the capacitor element A is suspended from a band-shaped metal plate G by welding the tip of the anode lead B led out from the capacitor element A. However, the length of the anode lead B is set to be sufficiently long, as shown by the dotted line in the figure, in order to improve workability when welding the first external lead member C to the anode lead B.

However, after the first external lead member C is welded to the anode lead B, it is cut and separated from the X-X section, and most of it is disposed of as waste material. If an expensive metal wire is used in the capacitor, the cost of the capacitor increases.

In view of these points, the present invention provides an electrolytic capacitor that has a simple configuration and can effectively reduce the cost of the capacitor.Examples will be described below.

In FIG. 3, reference numeral 1 designates a capacitor element constructed by press-molding metal powder having a valve action into a desired shape, for example, a cylindrical shape, and sintering it.

Reference numeral 2 denotes an electrode lead layer formed on the circumferential surface of the capacitor element 1 through an oxide layer and a semiconductor layer, and is composed of, for example, a paste layer polymerized on a graphite layer. It can also be configured.

3 is an anode lead led out from the capacitor element 1, and a first metal wire 4 having a valve action has a valve action whose melting point is lower than that of the first metal wire 4 and higher than the sintering temperature of the capacitor element 1. It is constructed by coaxially welding 6 a second metal wire 5.

The first metal wire 4 in the anode lead 3 is connected to the capacitor element 1.

In the illustrated example, these connections are made by planting the first metal wire 4 in the center of the metal powder prior to pressure molding, but for example, if one end of the first metal wire 4 is can also be connected to the circumferential surface of the capacitor element 1 by welding.

Reference numeral 7 denotes a first external lead member having an L-shape, for example, and a bent portion 7a thereof is welded to cross the second metal wire 5 of the anode lead 3.

Reference numeral 8 denotes a second external lead member having a straight shape, for example, and one end of which is soldered to the electrode lead layer 2 of the capacitor element 1.

Reference numeral 9 denotes a resin material applied so as to cover the main portion including the capacitor element 1.

Next, a specific method of assembling the capacitor will be explained with reference to FIGS. 4 to 6.

First, as shown in FIG. 4, the metal powder (tantalum powder with a melting point of 2997°C) filled in the die is punched into the first metal wire (tantalum wire) 4 of the anode lead 3 using upper and lower punches. The capacitor element 1 is formed by pressing and molding the powder into a cylindrical shape with the powder planted in the center and sintering it in a vacuum or inert atmosphere at a sintering temperature of 1,600 to 2,000°C.

Then, this capacitor element 1 is attached to a metal plate 10,
The second metal wire in the anode lead 3 (melting point is 2497°C
The upper end of the niobium wire) 5 is welded to the metal plate 10 to suspend it.

Further, an oxide layer, a semiconductor layer, and an electrode lead layer 2 are sequentially formed on the circumferential surface of the capacitor element 1 by a conventional method.

Next, as shown in FIG. 5, the L-shaped bent portion 7a of the first external lead member 7 extending from the first strip plate 11 is overlapped with the second metal wire 5 adjacent to the welding portion 6 and welded. do.

Then, the second metal wire 5 is cut from a portion X-x that is slightly away from the welded portion with the first external lead member 7 toward the band plate.

Next, as shown in FIG. 6, with the lower end of the straight second external lead member 8 extending from the second strip plate 12 in contact with the electrode lead layer 2 of the capacitor element 1, the molten solder bath is opened. Solder the two by dipping it in water and pulling it up.

Thereafter, the main portion including the capacitor element 1 is covered with a resin material 9, and the first and second external lead members 7 and 8 are cut from the Y-Y portion to form the solid electrolytic capacitor shown in FIG. get.

In this way, the anode lead 3 includes a first metal wire 4 having a valve action and a second metal wire 5 having a valve action whose melting point is lower than that of the first metal wire 4 and higher than the sintering temperature of the capacitor element 1. Since the first external lead member 7 is welded coaxially, the waste material of the anode lead 3 after welding the first external lead member 7 is almost limited to the second metal wire 5.

Therefore, even if expensive tantalum wire is used as the first metal wire 4, by using niobium, titanium, etc., which are cheaper than tantalum wire, as the second metal wire 5, the anode lead 3
Since the amount of tantalum wire used can be greatly reduced, the cost of the capacitor can be effectively reduced.

In particular, the smaller the capacitor element 1 is, the more remarkable the cost reduction effect becomes.

Further, since the anode lead 3 led out from the capacitor element 1 is constructed by coaxially welding the first metal wire 4 and the second metal wire 5, the first and second metal wires are connected at the welded portion. The die scratches formed on the surfaces of the metal wires 4 and 5 disappear.

For this reason, when the capacitor element 1 is immersed in a semiconductor mother liquor such as a manganese nitrate solution, the semiconductor mother liquor is
Although it creeps up through the die scratches on the surface of the metal wire 4 due to capillary action, further creeping up is prevented at the welded portion with the second metal wire 5.

Therefore, since there is no creeping up and adhesion to the second metal wire 5, even if the first external lead member 7 is welded to the second metal wire 5, there will be no short circuit between the anode and the cathode, and the electrolytic capacitor The reliability of the system can be improved.

However, such an effect cannot be expected when the welds are crossed and welded as disclosed in Japanese Unexamined Utility Model Publication No. 1774/1983.

Further, since the first external lead member 7 is usually made of a metal material such as iron, nickel, copper, etc., which has a relatively low melting point and can be soldered, the first external lead member 7 has a melting point lower than that of the first metal wire 4. If welded to the second metal wire 5 with a lower In this case, the difference in melting point between the two is compressed, and welding can be performed more reliably.

Generally, it is known that if the capacitor element 1 and the anode lead 3 are made of niobium, the leakage current characteristics will be impaired, but as shown in Figure 3, niobium is used only in a small part of the anode lead 3. Because of this, almost no characteristic deterioration occurs.

Furthermore, since the anode lead 3 is sintered in a state led out from the capacitor element 1, even if a niobium wire is used as the second metal wire 5, impurities contained in it can be removed as much as possible, and the third The first as shown in the figure
Even if the external lead member 7 of the capacitor is connected to the second metal wire 5, there will be almost no deterioration of the characteristics of the capacitor due to the fact that the amount of the second metal wire 5 used is small as described above. .

Note that the present invention is not limited to the above embodiments in any way,
For example, metals other than tantalum and niobium can be used in an appropriate combination as the first and second metal wires in the anode lead, as long as the above-mentioned conditions are satisfied between them.

Furthermore, although all of the embodiments described above relate to solid electrolytic capacitors, they can also be applied to wet electrolytic capacitors.

As described above, according to the present invention, since the parts other than the main part of the anode lead are replaced with metal wires having a lower melting point than the main part, it is possible to not only effectively reduce the cost of the capacitor, but also It can also improve weldability with external lead members,
Furthermore, by coaxially welding the first and second metal wires, die scratches on the surface are interrupted, and it is possible to prevent the semiconductor mother liquid from creeping up to the second metal wires.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a conventional example, Fig. 2 is a side sectional view for explaining the assembly method, Fig. 3 is a side sectional view showing an embodiment of the present invention, and Figs. 4 to 7 are A side sectional view for explaining an assembly method. In the figure, 1 is a capacitor element, 3 is an anode lead, 4
5 is a first metal wire, 5 is a second metal wire, and 6 is a welded portion.

Claims (1)

[Scope of utility model registration request] It comprises a capacitor element 1 formed by pressure-molding metal powder having a valve action into a desired shape, and an anode lead 3 derived from the capacitor element 1, and the anode lead 3 is made of a first metal having a valve action. A second metal wire 5 having a valve action whose melting point is lower than that of the first metal wire 4 and higher than the sintering temperature is coaxially welded to the wire 4, and the first metal wire 4 is connected to a capacitor. An electrolytic capacitor whose W indicates that it is connected to Niremen 1.