JPH01125902A - Varistor - Google Patents

Abstract

PURPOSE:To compensate a zinc oxide varistor and a strontium titanate varistor for their drawbacks and to obtain a varistor having a large electrostatic capacity by joining the two varistors to form one element, installing lead wires to it integrally and then subjecting it to resin molding. CONSTITUTION:A zinc oxide varistor 11 and a strontium titanate varistor 12 are put left and right and are bonded. An electrode 13 is provided on both the front and rear surfaces, and two lead wires 14 are soldered to each electrode. And then, a resin molding 15 is performed on the surface to form a product. A zinc oxide varistor has high surge resistance and high nonlinear coefficient, but its electrostatic capacity and nonlinear coefficient are small. A strontium titanate varistor absorbs sharp pulses in rise time, but its surge resistance and nonlinear coefficient are small. Therefore, the drawbacks of both varistors can be compensated.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention can be incorporated into various electronic circuits to absorb surge voltages and noise generated from switches, motors, etc., or instantaneous high voltages caused by lightning. The present invention relates to a varistor whose purpose is to protect various semiconductor devices and the like.

<Prior Art> Zinc oxide (2■O) varistors are commonly used as conventional varistors to absorb surge voltages.

This varistor has features such as high surge resistance, high nonlinear coefficient, and low limiting voltage.

<Problems to be solved by the invention> Since the capacitance of zinc oxide-based varistors as described above is small, the wave front is not suppressed for rapidly rising pulse voltages, resulting in overshoot and damage to electronic equipment. adversely affect.

For this purpose, as shown in the circuit diagram of FIG. 6, a capacitor 2 is connected in parallel to a zinc oxide varistor 1 to
13 is left unused.

However, the above-mentioned circuit requires soldering work to construct it, and there are problems such as the area occupied on the printed circuit board for attaching the parts increases.

This invention was made in order to solve the problems of the conventional zinc oxide-based varistors as described above. This study focused on the fact that the varistor has a large capacitance and can absorb fast-rising pulses, but has a small surge withstand capacity and a small nonlinearity coefficient, so the limiting voltage is large.

That is, this invention utilizes a zinc oxide varistor and a titanate varistor.
This device is made by joining the varistor with a varistor to form a single element, attaching lead wires to the element, making it an integral part, and then resin molding is performed.

<Embodiments> Examples of the present invention will be described below with reference to FIGS. 1 to 5 of the accompanying drawings.
This will be explained based on the diagram.

FIG. 1 shows a first example of the present invention, in which 11 is a zinc oxide-based varistor, 12 is a strontium titanate-based varistor, and these varistors 11 and 12 are arranged side by side and bonded. Electrodes 13 are provided on both sides, and two leads 11114 are soldered to each electrode.

Then, a resin mold 15 is applied to the surface to make a product.

In the second example shown in FIG. 2, the structure is the same as the first example except that the varistors 11 and 12 are square in nine points.

In the third example shown in FIGS. 3 and 4, a disc-shaped varistor 12 is fitted inside a ring-shaped varistor 11, but conversely, a disc-shaped varistor 11 is fitted inside a ring-shaped varistor 12. may be inserted.

In the fourth example shown in FIG. 5, varistors 11 and 12 are stacked and bonded one after the other, and in this case, the leads l! to the front and rear electrodes 13 are connected. 14 is soldered, and a lead $916 is led out from between the electrodes 13 and 13 on the joint surface. Here, two lead wires 14 are connected and connected to one line,
Connect lead wire 16 to the other line.

Figure 7 compares the characteristics of various varistors when a rectangular wave (a) is applied. (D) is a case in which the zinc oxide-based varistor of the present invention and the strontium titanate-based varistor are bonded.

Effect> As mentioned above, the varistor of this invention is made by joining a zinc oxide-based varistor and a strontium titanate-based varistor to form one element, attaching a lead wire to this element, and performing resin molding. The disadvantages of the zinc oxide-based varistor and the strontium titanate-based varistor can be mutually compensated for, and a varistor having the characteristics of both can be obtained.

Therefore, there is no need to solder the zinc oxide varistor and the capacitor as in the past, and there is no need to take up a large area for mounting the parts.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing a first example of the varistor of the present invention, FIG. 2 is a partially cutaway front view showing the second example, and FIG. 3 is a partially cutaway front view showing the third example. Part cutaway front view, No. 4
The figure is a longitudinal sectional view of the same as above, Figure 5 is a partially cutaway side view showing the fourth example, Figure 6 is a protection circuit diagram of electronic equipment when using a conventional varistor, and Figure 7 is a diagram of various conventional varistors. FIG. 3 is a waveform diagram comparing the characteristics when a rectangular wave is applied to a varistor and a varistor of the present invention. 11... Zinc oxide-based varistor 12... Strontium titanate-based varistor 13...
・Electrode 14...Lead wire 15...Resin mold Fig. 1 Fig. 2 Fig. 3 Fig. 244 Fig. WJ5 Fig. b Fig. 7

Claims (1)

[Claims] A varistor characterized in that a zinc oxide-based varistor and a strontium titanate-based varistor are bonded together to form a single element, a lead wire is attached to this element to integrate it, and then a resin mold is applied.