JPH0442506A - Voltage depending nonlinear resistance porcelain element - Google Patents

Abstract

PURPOSE:To strengthen an adhesive force between a common terminal and an element and to contrive the improvement in reliability by uniting a doughnut- form electrode of a semiconductor ceramic cylinder with an electrode of an inner circumferential plane and arranging a counter electrode on an outer circumferential plane on another end plane side at a distance from the end plane. CONSTITUTION:On one end plane of a sintered body, a doughnut-form electrode is arranged by using a conductive paste, and also an electrode is arranged on an inner circumferential plane and these electrodes are united into one body. Also, on another end plane side, a counter electrode is arranged on an outer circumferential plane at a distance from the end plane, followed by sintering to form electrodes 1 and 2. Next, a pin 4 and a common terminal 10 are attached and a periphery around an element 8 where electrodes 6 and 7 are arranged is molded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a voltage having capacitor characteristics and varistor characteristics to protect semiconductors and circuits of equipment from abnormal high voltage, noise, static electricity, etc. generated in electrical equipment and electronic equipment. The present invention relates to dependent nonlinear resistance ceramic elements.

Conventional technology Conventionally, SiC varistors and Z
nO type varistors are used. The voltage-current characteristics of such a varistor can be approximately expressed as in the following equation.

1 = (V/C)'' Here, ■ is current, ■ is 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, have a low dielectric constant, and have a small inherent capacitance, so they are hardly able 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 breaks down, 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.
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 the above-mentioned element mainly composed of 5rTiOJ/< which has the functions of both a risk and a capacitor is used to remove noise that enters from a connector etc., the configuration of the element is generally as follows. It looks like Figure 3. In Figure 3, 11
12 is an electrode, and 13 is an element.

In general, such an element is assembled into a connector as shown in FIG. However, when the configuration shown in FIG. 4 is used, a part of the solder 15 flows into the gap between the bottle 14 and the element 18, and the distance between the upper electrodes appears to become smaller, lowering the varistor voltage and causing polarity in the varistor voltage. This has the disadvantage that the insulation resistance becomes low. In FIG. 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 structure in which the varistor voltage does not change even if a part of the solder flows into the gap between the bottle and the element, the varistor voltage does not have polarity, and the insulation resistance does not change. It is something to do.

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 having a as a main component 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 donut-shaped electrode is provided that is small and has an inner circumference the same diameter as the through hole, 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 integrated. , the problem is solved by obtaining a voltage-dependent nonlinear resistance ceramic element characterized in that electrodes are provided on the outer peripheral surface of the cylinder on the other end surface side of the cylinder, facing each other at a distance from the end surface. This is what I am trying to do.

According to the configuration of 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 circumference of the through hole is An electrode is provided on the surface, the donut-shaped electrode and the electrode on the inner circumferential surface of the through hole are integrated, and on the other end surface side of the cylinder, an electrode is provided on the outer circumferential surface of the cylinder and faces at a distance from the end surface. With this configuration, one end surface of the cylinder and the inner peripheral surface of the through hole are integrated as one electrode, so when it is assembled into a connector etc., a drop of solder is placed in the gap between the bottle and the element. Even if the part flows in, the distance between the upper electrodes does not appear to change because it is above the integrated electrode. 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. In addition, by providing opposing electrodes on the outer peripheral surface of the cylinder on the other end surface side of the cylinder at a distance from the end surface, the surface insulation distance between the electrodes can be widened, so that the energized life characteristics can be improved. can be improved and reliability can be improved. Furthermore, when the common terminal is connected to the opposing electrode formed on the outer circumferential surface of the cylinder with a distance from the end surface using solder or the like, soldering can be performed from both sides of the common terminal, so that the common terminal and the element can be connected by soldering. This makes it possible to strengthen the adhesive force and improve reliability.

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

First, SrCO3, CaCO3, BaCO2゜Mg C
O3 and TiO2 were weighed at various composition ratios as shown in Table 1 below, and mixed in a ball mill for 24 hours. Next, after drying, it is calcined at 1050° C. for 4 hours, pulverized again in a ball mill for 24 hours, and then dried to obtain the first component.

Next, the first component, second component, and third component were weighed to have the composition ratio shown in Table 1 below, mixed for 24 hours using a ball mill, etc., dried, and mixed with 10 wt of an organic binder such as polyvinyl alcohol. After adding % and granulating,
With a press pressure of 1 (t/cd), the outer diameter is 4φ and the inner diameter is 1.
It is formed into a cylindrical shape with a diameter of 4 and a height of 2.5 tons, and is fired in air at 1100° C. for 12 hours to remove the binder. next,
Calcination is performed at 1450° C. for 3 hours in a reducing atmosphere, for example, a gas of N2:H2=9:1. After that, it is fired at 1020° C. for 6 hours in an oxidizing atmosphere, such as air.

On one end surface of the sintered body obtained in this way, 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 formed using a conductive paste such as Ag, for example by screen printing. At the same time, an electrode is provided on the inner peripheral surface of the through hole by a method such as roller transfer, so that the donut-shaped electrode and the electrode on the inner peripheral surface of the through hole are integrated. Further, on the other end surface side of the cylinder, electrodes facing each other at a distance from the end surface are provided on the outer peripheral surface of the cylinder by a method such as roller transfer, and the temperature is 630°C.

The electrode 1.2 is fired as shown in FIG. Moreover, in FIG. 1, 3 is an element.

Next, as shown in FIG. 2, solder 5. The pin 4 and the common terminal 10 are attached with solder 9 or the like, and the periphery of the element 8 provided with the electrodes 6.degree. 7 is molded with a resin (not shown) such as butadiene rubber. The characteristics of the element thus obtained are shown in Table 2 below for the element alone and after assembly of the connector.

In addition, in Table 2, V. , is the voltage applied across the element when a current of 1 mA flows, and V l +11,
The polarity is the difference between V1mA in the positive direction and V14 in the negative direction divided by VlmA in the positive direction, and the insulation resistance is between the bin 4 and the common terminal 10 when the applied voltage is 12 V, D, C. is the insulation resistance value of

(Margin below) Here, although only a portion of the proportion of Sr in the first component is replaced with CaBaMg is shown in the example, it is within the range of having both varistor and capacitor characteristics as the device characteristics. It doesn't matter if it's something like. Also, the second component.

Although only some combinations of the third component are shown in the embodiment, it may be any other component as long as it has both varistor and capacitor characteristics as the device characteristics. Furthermore, the noise removal effect can be improved by connecting an inductance made of, for example, a ferrite, a coil, or a toroidal coil to the voltage-dependent nonlinear resistance ceramic element.

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 an electrode is provided on the outer circumferential surface of the cylinder on the other end surface side of the cylinder at a distance from the end surface. By creating a structure in which electrodes are opened and facing each other, one end surface of the cylinder and the inner peripheral surface of the through hole are on the electrode integrated as one electrode, so the appearance is that between the upper electrodes. The distance does not change. 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. Effects can be obtained. In addition, by providing opposing electrodes on the outer peripheral surface of the cylinder on the other end surface side of the cylinder at a distance from the end surface, the surface insulation distance between the electrodes can be increased, so that the energized life characteristics etc. reliability can be improved. Furthermore, by making the element cylindrical, the length of the element becomes longer, but the dimensions of the element can be reduced in the radial direction, making it possible to reduce the pin spacing of the connector, making the connector more compact. It is effective for Furthermore, when the element is assembled into a connector or the like, since the common terminal can be soldered from both sides, the adhesive force between the common terminal and the element can be strengthened, and reliability can be improved. Furthermore, by connecting the common terminal to the opposing electrode portions, the height protruding from the common terminal can be reduced.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an element according to the present invention, Fig. 2 is a sectional view when the element according to the invention is assembled into a connector, and Fig. 3 is a sectional view showing an element according to the present invention.
The figure is a sectional view showing a conventional element, and FIG. 4 is a sectional view of the conventional 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.

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 resistance ceramic element, characterized in that an electrode is provided on the outer peripheral surface of the cylinder on the other end surface side of the cylinder, facing the electrode at a distance from the end surface. (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 selected from Ca, Ba, and Mg.