JPH03238802A - Voltage-dependent nonlinear ceramic resistor - Google Patents

Abstract

PURPOSE:To provide a varistor having stable electrical characteristics, constant varistor voltage, unpolarized varistor voltage, and constant insulating resistance by forming an annular electrode integrally with the electrode on the inner wall of a hollow cylinder and the opposite electrode on the outer cylinder surface on the other end of the cylinder. CONSTITUTION:An element 8 in the shape of a hollow cylinder has an electrode on the wall of its through hole, and it has one end provided with an annular electrode 6, which is smaller in outer diameter than the cylinder and equal in inner diameter to the cylinder. The electrode 6 is formed integrally with the electrode on the inner wall of the cylinder. The opposite electrode 7 is provided on the outer cylinder surface on the other end of the cylinder. Since the one end and inner wall of the cylinder form an integral electrode, the distance between the two electrodes remains unchanged even if solder 5 flows into the gap between the varistor element and a pin 4. Therefore, electrical characteristics are stabilized, the varistor voltage is constant and unpolarized, and the insulating resistance remains unchanged.

Description

Detailed Description of the Invention: Industrial Application Field The present invention has capacitor characteristics and varistor characteristics for protecting semiconductors and circuits of equipment from abnormal high voltage, noise, static electricity, etc. generated in electrical equipment and electronic equipment. This invention relates to a voltage-dependent nonlinear resistance ceramic element.

Conventional technology Conventionally, various electrical and electronic devices have been used to control abnormally high voltages, eliminate noise, eliminate sparks, and take measures against static electricity.
SiC varistors with voltage-dependent nonlinear resistance characteristics,
ZnO type nolisters and the like are used. The voltage-current characteristics of such a varistor can be approximately expressed as in the following equation.

α 1 = (V/C) Here, ■ is a current, ■ is a voltage, C is a constant specific to the varistor, and α is a voltage-current nonlinear index.

The α of SiC varistors is about 2 to 7, and the α of some ZnO-based varistors is as high as 50. Such varistors have excellent performance in absorbing relatively high voltages, but due to their low dielectric constant and small inherent capacitance, they have little ability to absorb relatively low voltages below the varistor voltage. It has no effect, and the dielectric loss tan δ is as large as 5 to 10%.

On the other hand, semiconductor capacitors with an apparent dielectric constant of about 5×10' and a tan δ of about 1% are used to remove these low voltage noises. However, when a voltage or current exceeding a certain limit is applied to such a semiconductor capacitor due to a surge or the like, the capacitance decreases or the semiconductor capacitor is destroyed, and the capacitor no longer functions as a capacitor.

Therefore, recently, a product that has SrTiO3 as its main component and has both varistor and capacitor properties has been developed, and it
It is used to protect semiconductor elements and circuits such as SI, and to remove noise that enters from cables and connectors that interconnect electronic devices.

Problems to be Solved by the Invention When an element having the functions of both a varistor and a capacitor, which mainly consists of 5rTi03, is used to remove noise entering from a connector etc., the structure of the element is generally as shown in Fig. 3. It looks like this. In FIG. 3, 11 and 12 are electrodes, and 13 is an element.

When such an element is incorporated into a connector, it generally becomes as shown in FIG. However, if you configure it as shown in Figure 4,
A portion of the solder 15 flows into the gap between the pin 14 and the element 18, which apparently reduces the distance between the upper electrodes, lowers the varistor voltage, and causes the varistor voltage to become polarized, resulting in lower insulation resistance. had. In Figure 4,
16 and 17 are electrodes, 19 is solder, and 20 is a common terminal.

Therefore, an object of the present invention is to provide an element having a configuration in which the varistor voltage does not change even if a part of the solder flows into the gap between the pin and the element, the varistor voltage does not have polarity, and the insulation resistance does not change. It is something.

Means for Solving the Problems In order to solve the above problems, in the present invention, 5rTiO
A semiconductor ceramic having voltage-dependent non-linear resistance characteristics mainly composed of s is formed to have a cylindrical through hole in the center of the cylinder, and one end surface of the cylinder has an outer periphery smaller than the outer diameter of the cylinder. A small donut-shaped electrode having an inner circumference the same diameter as the through-hole is provided, an electrode is provided on the inner circumferential surface of the through-hole, and the donut-shaped electrode and the electrode on the inner circumferential surface of the through-hole are integrated. The present invention attempts to solve the problem by obtaining a voltage-dependent nonlinear resistor ceramic element characterized in that opposing electrodes are provided on the outer peripheral surface of the cylinder on the other end surface side of the cylinder. be.

According to the present invention, a donut-shaped electrode having an outer circumference smaller than the outer diameter of the cylinder and an inner circumference having the same diameter as the through hole is provided on one end surface of the cylinder, and the inner circumferential surface of the through hole By providing an electrode on the inner peripheral surface of the cylinder, integrating the donut-shaped electrode and the electrode on the inner peripheral surface of the through hole, and providing an opposing electrode on the outer peripheral surface of the cylinder on the other end surface side of the cylinder. Since one end surface of the cylinder and the inner circumferential surface of the through hole are integrated as one electrode, even if some solder flows into the gap between the pin and the element, it will be on the integrated electrode, so the apparent The distance between the electrodes does not change. Therefore, the electrical characteristics are stable, the varistor voltage does not change, the varistor voltage has no polarity, and the insulation resistance does not change.

Example The present invention will be specifically described below with reference to Examples.

First, 5rCOi+ CaCO5, BaCO3, Mgc
o, Ti0z is weighed at various composition ratios as shown in Table 1 below, and mixed for 24 hours using a ball mill or the like. Next, after drying it, it was incinerated at 1050°C for 4 hours, crushed again for 24 hours using a ball, etc., and then dried to form the first precept.

Next, the 1st precept, 2nd component, and 3rd component were weighed so that the precipitate ratio was as shown in Table 1 below, mixed for 24 hours using a ball mill, etc., dried, and mixed with an organic compound such as polyvinyl alcohol. After adding 10-4% binder and granulating it, the outer diameter is 4φ and the inner diameter is 1.4 with a press pressure of 1 (t/cd).
It was formed into a cylindrical shape with a diameter of φ and a height of 2.5' (am), and was burned in air at 1100°C for 12 hours to remove the binder.

Then, it is burned out at 1450° C. for 3 hours in a reducing atmosphere, for example, a gas of Nz:1lz=9:1. Furthermore, after that, in an oxidizing atmosphere, e.g. air, at 1020°C for 6 hours.
Fire.

On one end surface of the sintered body thus obtained, a donut-shaped electrode with an outer circumference smaller than the outer diameter of the cylinder and an inner circumference the same diameter as the through hole is printed, for example, by screen printing using a conductive paste such as Ag. At the same time, an electrode is provided on the inner circumferential surface of the through hole by a method such as roller transfer, so that the donut-shaped electrode and the electrode on the inner circumferential surface of the through hole are integrated. Further, opposing electrodes are provided on the outer circumferential surface of the cylinder on the other end surface side of the cylinder by a method such as roller transfer, and burned at 630°C and 3 m1 to form the electrode 1 as shown in FIG. .2 is formed. Further, in FIG. 1, 3 is an element.

Next, as shown in Figure 2, the pin 4 and the common terminal 10 are attached using solder 5, solder 9, etc., and the area around the element 8 on which the electrodes 6 and 7 are provided with resin such as butadiene rubber (not shown), etc. mold. The characteristics of the element thus obtained are shown in Table 2 below for the element alone and after assembly of the connector.

In Table 2, VIIIA is the voltage applied to both ends of the element when a current of ImA flows, and the polarity of V ImA is the value obtained by dividing the difference between VIIIA in the positive direction and Vl+aAO in the negative direction by Vl, ^ in the positive direction. , and the insulation resistance is the applied voltage of 12V.
This is the insulation resistance value between pin 4 and common terminal 10 at DC.

(Left below) Also, some of the Sr for the first TIfc was converted into Ca, Ba,
Although only a portion of the ratio of substitution with Mg was shown in the embodiment, it may be any value as long as the element has both hinostar characteristics and capacitor characteristics. In addition, although the second component and the third t2 are shown for only some combinations in the example, any component may be used as long as it has both varistor and capacitor characteristics as the element characteristics. .

Effects of the Invention As described above, according to the present invention, a donut-shaped electrode is provided on one end surface of the cylinder, and the outer circumference is smaller than the outer diameter of the cylinder and the inner circumference has the same diameter as the through hole. , an electrode is provided on the inner circumferential surface of the through hole, the donut-shaped electrode and the electrode on the inner circumferential surface of the through hole are integrated, and the electrode is opposed on the outer circumferential surface of the cylinder on the other end surface side of the cylinder. By adopting a configuration in which one end surface of the cylinder and the inner circumferential surface of the through hole are integrated as one electrode,
Even if a part of the solder 5 flows into the gap between the bottle 4 and the element 8, the apparent distance between the electrodes does not change because it is on the integrated electrode. Therefore, the electrical characteristics are stable, the varistor voltage does not change, the varistor voltage has no polarity, the insulation resistance does not change, and even when the element is assembled into a connector, the change in characteristics before and after assembly is extremely small and stable. This effect can be obtained. In addition, by making the element cylindrical, the length of the element becomes longer, but the element can be made smaller in the radial direction, making it possible to reduce the interval between the bins of the connector, making the connector more compact. It is effective for

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an element according to the present invention, FIG. 2 is a cross-sectional view when assembled into an element connector according to the present invention, FIG. 3 is a cross-sectional view showing an element according to a conventional example, and FIG. 4 is a cross-sectional view showing an element according to a conventional example. FIG. 3 is a cross-sectional view of the element assembled into a connector. 1.2.6.7... Electrode, 3.8...
Elements according to the invention, 4... Bins, 5, 9...
...Solder, 10...Common terminal. Figure 1 Figure

Claims (2)

[Claims] (1) A semiconductor ceramic mainly composed of SrTiO_3 and having voltage-dependent non-linear resistance characteristics is formed to have a cylindrical through hole in the center of the cylinder, and the outer periphery of the cylinder is formed on one end surface of the cylinder. A donut-shaped electrode smaller than the outer diameter and having an inner circumference the same diameter as the through-hole is provided, and an electrode is provided on the inner circumferential surface of the through-hole, and the donut-shaped electrode and the electrode on the inner circumferential surface of the through-hole are provided. 1. A voltage-dependent nonlinear resistor ceramic element, characterized in that a voltage-dependent nonlinear resistor ceramic element is formed by integrating a plurality of electrodes, and further comprising opposing electrodes provided on the outer circumferential surface of the cylinder on the other end surface side of the cylinder. (2) The voltage-dependent nonlinear resistance ceramic element according to claim 1, wherein a part of the main component Sr is replaced with at least one element among Ca, Ba, and Mg.