JPS607701A - Voltage depending nonlinear resistor porcelain composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention produces a voltage-dependent nonlinear resistor (hereinafter referred to as a varistor) that is used for abnormal voltage absorption and noise removal in various electrical and electronic devices. The present invention relates to a voltage-dependent nonlinear resistor ceramic composition suitable for.

Conventional structure and its problems Traditionally, it has been used to absorb abnormally high voltages (hereinafter referred to as surges) and remove noise in various electrical and electronic devices.

SiC varistors, ZnO-based varistors, and the like having voltage-dependent nonlinear resistance characteristics have been used to eliminate sparks and the like. The voltage-current characteristics of such a varistor can be approximately expressed as follows.

I=(V/C) "Here, E is the current, V is the voltage, C is a constant specific to the varistor, and α is the voltage nonlinear index.

The α of 81C varistors is about 2 to 7, and the α of some ZnO-based varistors is as high as 60. Although such varistors have excellent performance in absorbing relatively high voltages such as surges, their low dielectric constant and small specific capacitance prevent them from absorbing low voltages below the varistor voltage (e.g. noise, etc.). ), and the dielectric loss angle (tan δ) is as large as 5 to 10 inches.

On the other hand, in order to remove these noises, the apparent dielectric constant can be reduced to 5X by appropriately selecting the composition and firing conditions.
Semiconductor ceramic capacitors with a size of about 10' to 6×10 4 and a tan δ of around 1 inch are used.

However, this semiconductor porcelain capacitor may be destroyed if a current exceeding a certain limit is applied to the element due to a surge, etc.
It may no longer function as a capacitor.

For the reasons mentioned above, in electrical and electronic equipment, varistors are usually used in combination with capacitors and other parts (e.g. coils) for purposes such as surge absorption and noise removal.For example, noise filters are The configuration is like this.

Figure 1 shows a general conventional noise filter circuit, and Figure 2 shows a conventional noise filter circuit configured by combining a varistor, a capacitor, and a coil.
Koinope 2 is a capacitor and 3 is a varistor.

However, the configuration shown in FIG. 2 has the disadvantage that the number of parts inside the device increases and it is contrary to the trend toward miniaturization of devices.

Purpose of the Invention The present invention eliminates the drawbacks of conventional surge absorption and noise removal as described above, and provides a composite function that has the functions of both a varistor and a capacitor and can perform surge absorption and noise removal with a single element. The object of the present invention is to provide a porcelain composition suitable for making a varistor having a porcelain composition.

Structure of the Invention In order to achieve the above-mentioned objects, the present invention is directed to the use of 5rTi.
03, Nb2O5 and Ta205 as metal oxides for promoting semiconductor formation, and MnO2 and Ga as additives.
Pt, TI, Si, Ti, Li, La,
The present invention proposes a voltage-dependent nonlinear resistor ceramic composition containing a predetermined amount of at least one element selected from the group consisting of Cu.

Description of examples The present invention will be specifically described below with reference to Examples.

5rTi03 and Nb205, Ta205 and MnO2
, ThO are weighed so as to have the composition ratio shown in the table below, mixed wet for 6 hours using a ball mill or the like, dried and then calcined in air at 100°C to 126°C for 11 to 6 hours. After that, it was wet-pulverized for 4 hours using a ball mill or the like, dried, and then 8 wt % of a binder (for example, polyvinyl alcohol, etc.) was added and granulated.
0πmφ×1. Apply pressure 1 to the shape of Qfflfft. o
Pressure molding was performed at t/2. This molded body is heated to 130 m in a reducing atmosphere (for example, N2:H2=10:1).
It was fired at 0-1450'C for 1-6 hours. The thus obtained fired body had a specific resistance of 0.1 to 8Ω·m, and an average particle size of 20 to 60 μm. Next, this fired body is fired in air at 1000 to 1300'C for 0.5 to 6 hours,
A sintered body 4 as shown in FIG. 3 was obtained. Furthermore, the side planes of the sintered body 4 were polished with an abrasive such as SiC, and electrodes 6 were formed using a conductive metal such as Ag.

The diameter of the electrode 6.6 was set to ei, o mmφ.

The characteristics of the device thus obtained are also shown in the table below.

Here, the characteristics of the device as a varistor are evaluated using α and C in the voltage-current characteristic formula % formula % (where, engineering is current, ■ is voltage, Cid is a constant specific to the varistor, and α is a nonlinear index). Is possible. - However, since it is difficult to accurately measure C, in the present invention, the varistor voltage per unit thickness when a varistor current of 177 LA flows (hereinafter v1mA
/π7j) and tx = 1/iog (Vx
omA/V1mA) (However, if vlOmA, IQmA
varistor voltage when a varistor current of 177LA is flowing, VlmA is the varistor voltage when a varistor current of 177LA is flowing)
Characteristics as a varistor are evaluated based on the value of . In addition, the characteristic evaluation as a capacitor is performed at a measurement frequency of 1KHz.
dielectric constant ε at .

The dielectric loss angle tan δ is used. The above data is based on a firing temperature of 1 hour at 1400°C in a reducing atmosphere for 92 hours, and a firing temperature of 1 hour at 1200'C in air.

This was done in 3 hours.

As mentioned above, Nb205 and Ta205 form a solid solution in the crystal mainly composed of K5rTi03 during reduction firing, and the specific resistance of the sintered body can be lowered to around 1.0Ω・α by controlling the valence. By re-firing in the sintered body, a high-resistance layer is formed at the grain boundaries of the sintered body, exhibiting crystallization characteristics.

In addition, Nb2O5 is mixedly contained in TlO2 in the raw material, and normally industrially refined raw materials contain 0.
．． 001 to 0.200 molar content.

When 5rTi03 is made into a semiconductor using only Nb2O5, the specific resistance tends to be somewhat high, and although it exhibits varistor characteristics, the characteristics are unstable. However, when Ta205 is added to Nb2O5, the resistivity can be lowered and stable characteristics can be obtained. If the amount of Ta2O is too large, solid solution of other additives will be inhibited, so the appropriate amount is 0.001 to 5.000 mol.

When MnO2 is added, the material exhibits varistor characteristics, but the dielectric constant becomes small and tan δ becomes large.

However, when Te20 is added at the same time, both α and the dielectric constant increase. Since tan δ becomes smaller, the characteristics are significantly improved.

As the amount of MnO2 added increases, tanδ increases,
Since the properties deteriorate, 0.001 to 2.000 mol% is appropriate.

Since the dielectric constant of Te20 decreases as the amount added increases, an appropriate amount is 0.001 to 2.000 mol%.

Therefore, the sintered body obtained within the composition range shown in 2 can function as both a varistor and a capacitor.

In addition, although the case where only T620 was used alone was explained in the example, Ga was used in place of this.

It has been confirmed that similar effects can be obtained by using oxides of Pt 2 , Si 2 , Ti 2 , Li 2 , La 2 , and Cu individually within the above-mentioned predetermined amounts. In addition, these Ga,
Pt.

It has been confirmed that similar effects can be obtained by using two or more oxides of T7I, Si 2 , Ti 2 , Li 2 , La 2 , and Cu in such a way that the total amount added to 1 falls within the above specified amount range. .

A circuit like the one shown in Figure 4 was created using the elements described in ``2'', and the output situation was investigated for a noise input person as shown in Figure 6. As a result, the output situation curve B in Figure 6 shows the result. I was able to suppress the noise.

In FIG. 6, 7 is an element of the present invention, and 8 is a coil.

Note that the output condition of the conventional filter circuit shown in FIG. 1 is as shown by the output condition curve C in FIG. 6, and noise is not removed sufficiently. A conventional filter circuit including the shredded varistor shown in FIG. 2 can achieve an effect similar to the circuit shown in FIG. Become.

Effects of the Invention As mentioned in Section 2, the device using the ceramic composition of the present invention has an unprecedented complex function, and can play the roles of a varistor and a capacitor at the same time. It simplifies circuits and contributes to miniaturization, high performance, and cost reduction, and is useful for absorbing surges in various electrical and electronic devices.

This can be extended to noise removal, and its practical value is extremely large.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams showing conventional noise filter circuits, Figure 3 is a cross-sectional view of an element using the ceramic composition of the present invention, and Figure 4 is a noise filter using the element shown in Figure 3. FIG. 6 is a circuit diagram showing the filter circuit, and is a characteristic diagram showing the input noise and output noise situations of the present invention and the conventional noise filter circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure I Figure 3, 6 Figure 4 Figure 5 Number of liquid per candle (IMHz) 5

Claims (1)

[Claims] 99.996 to 90.800 mol of 5rTi03 and 0.001 mol of Nb2O5 as a metal oxide for promoting semiconductor formation.
~0.200 Mo#%, Ta205 ○, oo1~5.
Oo○ Contains molti, Mn is in the form of MnO2, ○, ○0
1-2, OOO%, Ga, Pt, TI
, Si, Ti, Li. At least one element selected from the group consisting of La, Cu and Ga2O3. p to,'r 7!
20, 5i02. 0 in the form of TiO2, Li2O, La2O3, CuO
．． A voltage-dependent nonlinear resistor ceramic composition characterized by containing oo1 to 2,000 molti.