JPH01289221A - Manufacture of voltage-dependent nonlinear resistance element - Google Patents

Abstract

PURPOSE:To obtain a voltage-dependent nonlinear resistance element having an excellent characteristic by a method wherein a paste composed mainly of Cu is dried in the air and an ohmic electrode is formed on a sintered substance composed mainly of SrTiO3. CONSTITUTION:A paste whose main component is Cu and which contains a borosilicate lead-based glass frit and a resin is applied, by using a screen printing method, to a region used to form electrodes of a sintered substance 1 composed mainly of SrTiO3. Then, this paste is dried in the air, a resistance element having ohmic electrodes 2a-2c composed mainly of Cu is obtained on the sintered substance 1. By this setup, the electrodes come into ohmic contact with the sintered substance, and an interface between the sintered substance and the electrodes has not rectification action; accordingly, voltage nonlinearity of the sintered substance itself can be displayed sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses a 5R
The present invention relates to a method of manufacturing a voltage-dependent nonlinear resistor element using a sintered body containing TiO as a main component.

Conventional technology Voltage-dependent nonlinear resistor elements have a resistance value that changes nonlinearly depending on the voltage applied between electrodes provided on the surface of a sintered body, and when the applied voltage exceeds a certain level, the resistance changes. It has the property that the value decreases rapidly. Taking advantage of this property,
It is widely used to eliminate sparks and remove noise from DC motors in electronic devices, to eliminate and protect relay contacts, to protect and prevent malfunctions of ICs and LSIs, and to absorb discharge from cathode ray tube circuits in television receivers.

As conventional voltage-dependent nonlinear resistor elements, those based on ZnO, SnO□, Fe2O, SiC, Tie2, etc. are known. Among these, 5n02 series and Fe2
In the O3 system, the sintered body itself is a linear resistor, and by adding a special electrode to it, an energy barrier is formed between the sintered body and the electrode, and varistor characteristics are obtained. Further, since the ZnO system and the 'rio2 system obtain varistor properties at the grain boundaries, and the SiC system obtains varistor properties at the contact surfaces between particles, special Ktli is not selected. On the other hand, in terms of characteristics, Z
The nO type and SiC type have large nonlinearity and show excellent effects on absorbing relatively high voltages, but have small dielectric constants and have little effect on absorbing relatively low voltages.
system.

The Fe2O3 system and the τi02 system have small nonlinearity and insufficient energy absorption. Therefore, recently, 5rT, which has a large dielectric constant and is effective in absorbing relatively low voltage, has been developed.
The i05 series is being developed.

Problems to be Solved by the Invention However, the conventional voltage-dependent nonlinear resistor elements described above have a small dielectric constant and a high varistor voltage, so they are not effective in absorbing relatively low voltage surges and noise. There are problems with the sintered body itself, and because the contact between the sintered body and the electrode is non-ohmic, a type of rectification effect occurs at the interface between the sintered body and the electrode. There is a problem with the combination of the sintered body and the electrode, such as not being able to effectively utilize the excellent nonlinearity.

The present invention solves these problems and is a voltage-dependent electrode structure that fully utilizes the excellent properties of the sintered body, has strong adhesion of the electrode to the sintered body, and has a low material cost. The object of the present invention is to provide a nonlinear resistor element.

Means for Solving the Problems In order to solve the above problems, in the present invention, 5rTi0
．． A paste containing Cu as a main component is dried in air on a sintered body containing Cu as a main component to provide an ohmic electrode. In addition, some of the Sr in 5rTiO5 is replaced with C
The main component of the sintered body is one in which one or more of a, Ba, and Mg are substituted.

Function When a normal electrode is applied to a sintered body mainly composed of 5rTi03, the electrode comes into non-ohmic contact with the sintered body, a rectifying effect occurs at the interface between the sintered body and the electrode, and the sintered body The excellent ballista properties one possesses are dulled, making it impossible to fully demonstrate their original properties. Therefore, the electrode must be in ohmic contact with 5rTi03. An electrode made of an In-GIL alloy may be used as the electrode for ohmic contact. However, In-Ga alloy is expensive and not suitable for mass production, and the only way to attach In-Ga alloy to a sintered body is by rubbing or ultrasonic brazing. The force is weak and electrode peeling defects are likely to occur. Furthermore, the In-Ga alloy has a low melting point, making it difficult to solder lead wires.

Therefore, in the present invention, as a result of considering a simple electrode formation method and a relatively low cost electrode material, drying in air was adopted as the electrode formation method, and carbon dioxide was used as the electrode material.
U was adopted. Conventionally, Cu easily oxidizes when fired in air, making it difficult to use for electrodes.
An ohmic electrode containing Cu as a main component can be easily formed by appropriately selecting and using a paste containing Cu as a main component such as the particle size of u. In addition, Ou is significantly cheaper than Zn-Ga alloy, is easy to mass-produce, has a very strong adhesion between the sintered body and the electrode, is less likely to cause electrode peeling defects, and has little change over time, making it highly reliable. This means that it is possible to provide a 5rTiO5-based voltage-dependent nonlinear resistor element that has high resistance and is inexpensive.

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

First, 5r (50s, TiO2 is weighed to have a ratio of 5rTi03, mixed for 15 hours using a ball mill, etc., dehydrated and dried, calcined at 1100°C for 4 hours, and then mixed again for 20 hours using a ball mill etc. Grind, dehydrate and dry, 5
Synthesize rTi03. 5rTiO310 thus obtained
Weigh out 0.2 mol part of Nb2O5, 0.1 mol part of CuO, and 0.15 mol part of MnO2 to 0%# part, mix for 20 hours using a ball mill, etc., and dehydrate and dry. Next, 10 wt % of an organic binder such as PVM (polyvinyl alcohol) is added and granulated, and formed into a donut shape with a hole in the center. This molded body is placed in the air for 1
After firing at 100°C for 2 hours, firing at 1400°C for 8 hours in a reducing atmosphere of N2:H2=s:1, and then firing at 1060°C for 12 hours in air, as shown in Figures 1 and 2. A sintered body 1 as shown is created. Next, a paste containing Cu as a main component, lead borosilicate glass frit, resin, etc. is applied to the regions of the sintered body 1 where the electrodes are to be formed (three locations in this example) by screen printing or the like. After that, by drying in air at 120°C for 5 minutes, the sintered body 1 is coated with an ohmic electrode 2fL mainly composed of Cu.
, 2b.

A voltage-dependent nonlinear resistor element having 2C is obtained.

Here, the average particle size of Cu used was 3 μm.

In this example, only a donut-shaped element is shown, but other shapes (for example, a disk-shaped element) are shown.

It may be cylindrical, square plate, etc.). In addition, a part of Sr, which is the main component of the sintered body, is replaced by Ca and Ba.

One or more elements of Mg may be substituted, and the additive may have any components.

Effects of the Invention As described above, according to the present invention, the obtained electrode makes ohmic contact with the sintered body, and there is no rectifying effect at the interface between the sintered body and the electrode, so that the sintered body It is possible to fully utilize its own voltage nonlinearity. Furthermore, since the adhesive force between the sintered body and the electrode is very strong, defects such as electrode peeling are unlikely to occur, and reliability is extremely high. Also, In-
Compared to the case where a Ga alloy is used, the cost of electrode materials is much lower, making it suitable for mass production.

[Brief explanation of the drawing]

FIG. 1 is a top view showing one embodiment of a device obtained by the manufacturing method of the present invention, and FIG. 2 is a sectional view thereof. 1...Sintered body, 2m, 2b, 2c...
...Ohmic electrode. Name of agent: Patent attorney Toshio Nakao and one other name
1 Figure and / Figure 2 2t / Keomitsu 7 piezoelectric food / Keo body /

Claims (2)

[Claims] (1) A method for manufacturing a voltage-dependent nonlinear resistor element, characterized in that an ohmic electrode made by drying a paste mainly composed of Cu in air is provided on a sintered body mainly composed of SrTiO_3. . (2) Part of Sr in SrTiO_3 is Ca, Ba, Mg
2. The method for manufacturing a voltage-dependent nonlinear resistor element according to claim 1, wherein the main component of the sintered body is one or more of the above elements.