JP2000150207A - Voltage nonlinear resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a varistor at a low cost with high reliability without the necessities of a complex manufacturing process and any members of an insulator, etc., by forming weak portions having fuse functions in at least one of its lead wires, and by coating the weak portions with an encapsulating resin for armoring a sintered body. SOLUTION: On both surfaces of a sintered body 1 having its diameter of about 10 mm and made of zinc oxide of its main component including magnesium oxide, bismuth oxide, and cobalt oxide, etc., as additives, silver electrodes 2 having their diameters of about 8 mm leaving as a margin are printed to burn the intermediate at about 1200 deg.C. Further, lead wires 3 having their diameters of about 0.8 mm one of which has as a weak portion a notch portion 5 having its diameter of about 0.3 mm and its length of about 0.5 mm are soldered to the electrodes 2, and the lead wires 3 are so coated with an encapsulating resin 4 as to pack the notch portion 5. Thereby, a varistor having its safety function of 220 V as a varistor voltage is created. Still, the shape of the weak portion is not limited to the foregoing as far as it suffices for a fuse function, and its forming method is not limited only to notching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a voltage non-linear resistor having a security function.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional voltage non-linear resistor (hereinafter referred to as a varistor) has electrodes 2 formed on both sides of a sintered body 1 and a lead wire 3 is soldered to the electrodes 2. And a resin exterior 4. When an overvoltage or an excessive surge is applied to such a varistor, the varistor is destroyed and short-circuited. If the current from the power supply circuit continues to flow, the varistor generates heat and may be ignited in some cases. For this reason, a fuse is provided on the circuit in order to prevent such a problem.

[0003] A varistor is combined with an appropriate fuse,
In order to prevent the risk of fire when the varistor is destroyed, various proposals have been made in the past in which the varistor and the fuse are integrated and the varistor itself has a security function. For example, in JP-A-2-47842,
Japanese Patent Application Laid-Open No. 9-129403 discloses a technique in which a two-part planar electrode is connected to a crossover electrode made of a narrow and easily soluble metal provided on a heat-resistant insulating layer to provide a security function. A technique has been proposed in which a lead wire formed and provided thereon and an electrode of a varistor element are connected by a fuse acting body.

[0004]

However, such a conventional technique has a problem that the manufacturing process is complicated in order to provide a varistor with a security function, and that members such as insulators are required, which increases costs. was there.

[0005]

In order to solve the above-mentioned problems, in the varistor according to the first aspect, electrodes are provided on both surfaces of the sintered body, and lead wires are drawn out from the electrodes on both surfaces of the varistor. In a varistor in which the body is covered with a resin, a weak point having a fuse function is formed on at least one of the lead wires, and the weak point is covered with a resin covering the sintered body. It is.

According to the varistor according to the present invention, electrodes are provided on both surfaces of the sintered body, lead wires are drawn out from the electrodes on both surfaces, and at least one of the lead wires in the varistor in which the sintered body is covered with a resin. The lead wire is blown before the varistor generates heat or fire due to a simple structure in which a weak portion having a fuse function is formed and the weak portion is covered with an exterior resin that covers the sintered body. Since such a security function is provided, a complicated manufacturing process and members such as an insulator are not required, and a low-cost and highly reliable varistor can be provided. In addition, since the weak portion of the lead wire is covered with the exterior resin and reinforced, there is no problem in the strength of the lead wire.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A varistor according to the present invention is manufactured as follows as an example. Silver electrodes are printed on both sides of a sintered body containing zinc oxide as a main component with a margin, and formed by firing. Furthermore, a lead wire is soldered to the electrode, a weak point is provided on one of the lead wires, and the exterior is coated with an epoxy resin, thereby producing a varistor with a security function.

According to the varistor with a security function manufactured as described above, when a large current flows, the weak portion acts as a fuse and the lead wire is blown. As a result, a highly reliable varistor can be provided. Further, since the weak portion of the lead wire is covered with the exterior resin and reinforced, there is no problem in the strength of the lead wire.

Further, the weak point portion only needs to be such that the weak point portion and subsequent portions do not come into contact with the electrode within the range covered by the exterior resin.
In FIGS. 1 and 2, a weak point is formed in the sagging part of the resin, but when attaching the lead wire to the electrode, bend the lead wire away from the electrode, or attach an insulator between the lead wire and the electrode. The weak point can also be formed on the sintered body by interposing.

A specific embodiment will be described below with reference to the drawings. Here, FIG. 1 is a structural view of the present invention, and FIG. 2 is an enlarged view seeing through a hanging portion A of the resin.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2, a silver electrode of φ8 with a margin is provided on both sides of a φ10 sintered body 1 containing zinc oxide as a main component and magnesium oxide, bismuth oxide, cobalt oxide and the like. 2 was printed and fired at 1200 ° C. Further, a φ0.8 lead wire 3 having a notch 5 having a thickness of 0.3 mm and a length of 0.5 mm as a weak point on one of the lead wires is soldered to the electrode 2, and an outer package is formed so as to wrap the notch 5. A varistor with a security function having a varistor voltage of 220 V was produced by coating with a resin 4.

[0012] Twenty varistors each having a security function were manufactured by the method of the embodiment, and when 220 V AC was applied, the security was examined. As a result, all the varistors were open and the effectiveness of the security function was confirmed.

The weak point is not limited to the shape of the above embodiment, but may be any as long as it has a fuse function. The forming method is not limited to the notch alone. Further, a sintered body, an electrode, and an exterior resin having a varistor function can be appropriately selected, and it goes without saying that the present invention has the same effect in any case.

[0014]

As described above, according to the present invention, a highly reliable varistor with a security function can be provided without requiring complicated manufacturing steps and members such as insulators.

[Brief description of the drawings]

FIG. 1 is a structural view of the present invention.

FIG. 2 is an enlarged view showing a drooping portion A of resin.

FIG. 3 is a structural view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sintered body 2 Electrode 3 Lead wire 4 Exterior resin 5 Notch

Claims (1)

[Claims] An electrode is provided on both surfaces of a sintered body, and lead wires are drawn out of the electrodes on both surfaces of the sintered body. Forming a weak point having a fuse function,
A voltage non-linear resistor, wherein the weak point portion is covered with an exterior resin for exteriorly covering the sintered body.