JPH0113417Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a solid electrolytic capacitor with a safety function.

Conventionally, the structure of this type of capacitor is as shown in FIG. 1, in which an anode wire 1 having a valve action is planted and a capacitor element 2 is formed by molding and sintering metal powder having a valve action. Connect the lead wire 3, and then connect the fuse 5, which was previously connected to the cathode lead wire 4, to the capacitor element 2 with solder 6.
After that, an exterior (not shown) is applied.

However, with the solid electrolytic capacitor configured as described above, the heating when the fuse 5 is soldered 6 to the capacitor element 2 has a worse effect on the element than when the cathode lead wire is directly soldered, and the leakage current characteristics are deteriorated. It is extremely difficult to reliably connect the fuse 5 to the capacitor element 2 at the same time that the fuse 5 is deteriorated, and has the disadvantage that it is not practical.

The present invention was developed in view of the above points, and by arranging a conductive molded body with a fuse function between the anode wire and the anode lead wire, the characteristics are improved and safety is ensured when a short circuit current occurs. The purpose is to provide a solid electrolytic capacitor that performs its functions.

An embodiment of the present invention will be described below with reference to the drawings. That is, as shown in FIG. 2, an anode wire 11 having a valve action is planted, and a metal powder having a valve action, such as tantalum, niobium, or aluminum, is molded and sintered to form an anode body. A cathode lead wire 13 is connected to a capacitor element 12 in which an oxide film layer, a semiconductor oxide layer such as manganese dioxide, a graphite layer such as carbon, and a metal conductive layer are successively laminated on the surface thereof. Next, an insulating plate 14 made of, for example, Teflon, synthetic resin, or rubber is placed around the anode wire 11, passing through the anode wire 11, and placed on the insulating plate 14 as shown in FIGS. 3A and 3B. Anode wire fitting hole 15 approximately in the center
A conductive molded body 16 having a formed thereon is disposed. The conductive molded body 16 is made of, for example, Bi, Pb, Sn, Cd, In,
In addition to so-called fusible alloys with low melting points that have eutectic or near-eutectic combinations of multi-element alloys of two or more elements such as Zn and Sb, for example, phenols, epoxies, polyesters, etc., which have higher melting points than the fusible alloys. Thermosetting resins or them, such as talc,
Added fillers such as silica and alumina, or thermoplastic resins such as polyethylene, polyamide, polyimide, fluorine, silicon, polyphenylene sulfide, and ethylene fluoride, such as talc, silica, alumina, etc. It is made of a plastic material containing fillers such as, for example, or kneaded with a plastic material made of synthetic rubber such as fluorine, silicone, or butadiene.
Then, the protrusion of the anode wire 11 from the upper surface of the insulating plate 14 is fitted into the anode wire fitting hole 15, and the conductive molded body 16 is heated, causing the resin constituting the conductive molded body 16 to undergo thermal contraction. After the anode wire 11 and the conductive molded body 16 are integrally fixed using a method, an anode lead wire 17 is connected to the surface of the conductive molded body 16, and then an exterior resin 18 is applied.

When a short-circuit current flows through the solid electrolytic capacitor configured as above while using the solid electrolytic capacitor, capacitor element 1
2 generates heat, thereby melting the fusible metal that constitutes the conductive molded body 16 interposed between the anode wire 11 and the anode lead wire 17, and as a result, the molten metal present in at least the outer layer of the conductive molded body 16 melts. The molten metal is extruded, and although the conductive molded body 16 retains its original shape, it loses its conductivity and becomes a mere insulator, and the anode wire 11 and the anode lead wire 17 are electrically cut off. It is released from the circuit. Further, since the fuse is not soldered directly to the capacitor element as in the conventional method, there is no need to heat the capacitor element 12 more than necessary, and there is an advantage that leakage current characteristics due to heat are not deteriorated.

Next, a comparison of leakage current characteristics between the present invention a shown in FIG. 2 and the conventional example b shown in FIG. 1 will be explained with reference to FIG. In other words, Figure 4 shows the rating of 20V.DC-
This figure shows the leakage current characteristics of 50 samples each of a and b of the present invention a and conventional example b using 4.7μF tantalum solid electrolytic capacitors. Furthermore, this invention a
The conductive molded body used was a mixture of silicone rubber and a fusible alloy containing 67.75% Sn and 32.25% Cd. As can be seen from FIG. 3, the present invention a has a small average value and variation, whereas the conventional example b has a large average value and variation, indicating that the present invention a greatly contributes to the improvement of leakage current characteristics. In the above embodiment, the explanation was limited to a case where the lead wires run in the same direction and a resin sheath as the exterior, but it goes without saying that the present invention is equally effective when applied to a case exterior structure, and can also be applied to a case where the lead wires run in opposite directions.

As described above, according to the present invention, a conductive molded body in which a fusible alloy having a fuse function and a plastic material having a higher melting point than the fusible alloy is disposed between the anode wire and the anode lead wire. By doing so, it is possible to obtain a solid electrolytic capacitor that has good leakage current characteristics and can reliably perform the safety function when a short circuit current occurs.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a solid electrolytic capacitor according to a conventional example, FIG. 2 is a sectional view showing a solid electrolytic capacitor according to an embodiment of the present invention, and FIGS. A is a perspective view, B is a sectional view taken along the line A, and FIG. 4 is a comparison diagram of the leakage current characteristics of the present invention and a conventional example of the conductive molded body constituting the capacitor. 11... Anode wire, 12... Capacitor element, 1
3... Cathode lead wire, 14... Insulating plate, 16...
Conductive molded body, 17... Anode lead wire.

Claims (1)

[Scope of utility model registration request] a capacitor element in which an anode wire is planted and molded and sintered; an insulating plate disposed around the anode wire through the anode wire; and an insulating plate disposed integrally with the anode wire protrusion on the insulating plate. A conductive molded body formed by kneading a fusible metal and a plastic material having a higher melting point than the fusible metal, an anode lead wire connected to the conductive molded body, and a cathode lead wire connected to the capacitor element. A solid electrolytic capacitor equipped with