JPS59147409A - Voltage dependence 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 expressed approximately as follows: 0r = (v7cf) where I is the current, ■ is the voltage, C is a constant specific to the varistor, and α is the voltage difference. OS i C h IJ which is a linear index
The α of the varistor is about 2 to 7, and the a of the ZnO varistor is 60.
There are many things. 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). ), it has little effect on the dielectric loss angle (tan
δ) is also large at 6-10%.

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' and a tan δ of about 1% 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, varistors, capacitors, and other parts (e.g., coils) are usually used in combination with electrical and electronic equipment 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.
is a coil, 2 is a capacitor, and 3D varistor.

However, the configuration shown in FIG. 2 has the drawbacks of increasing the number of parts inside the device and contradicting 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 objects, the present invention
T 103 and Dy as a metal oxide for promoting semiconductor formation.
2O3, Na, Ca, Cd, In, Ea, Pb.

The present invention proposes a Guhi voltage-dependent nonlinear resistor ceramic composition containing a predetermined amount of at least one element selected from the group consisting of Ag and Ce.

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

<Example 1> SrTiO3, Dy2O3, and BaO were weighed to have the composition ratio shown in Table 1 below, mixed wet for 6 hours using a ball mill, etc., dried, and heated in air for 10 hours.
Calcinate at 00 to 1250°C for 1 to 6 hours.

Thereafter, the powder was wet-pulverized for 4 hours using a ball mill, etc., dried, and granulated with 8 wt % of an organic binder (e.g. polyvinyl alcohol).
mm ) φx 1. Press pressure 1.0 into o (gasp) t shape
Pressure molding was performed at t/art. This molded body is placed in a reducing atmosphere (
For example, 1300 to 1460 at N2:N2-10:1)
C. for 1 to 6 hours. The specific resistance of the fired body thus obtained is 0.1 to 0.80 cm, and the average particle size is 20 to 6 cm.
It was 0 μm. Next, this fired body was heated in air for 1000
It was fired at ~1300°C for 0.6 to 6 hours to obtain the sintered body 4 shown in FIG. Further, both 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 Aq. The diameter of the electrodes 6, 6 is 6.0 (m
m) φ.

The characteristics of the device thus obtained are shown in Table 1.

Margin belowHere, the characteristic evaluation of the element as a varistor is the voltage-current characteristic formula % formula described above. This can be done by α and C in . However, since it is difficult to accurately measure C, in the present invention, a varistor current of 1 mA is applied to
(risk voltage (hereinafter v1mA/
mm) and α=1/lOq(v1omA/■
1 mA) [However, ■ 1゜mA is determined by the value of 7 (risk voltage, VlrnA is 1 mA) (varistor voltage when a varistor current flows) when a varistor current of 1 omA flows. Characteristics are being evaluated.In addition, the characteristics of the capacitor 7 are evaluated at measurement frequency 1 with 1'(z
The above data is based on the dielectric constant ε and dielectric loss angle tan δ, respectively.
The test was carried out at 00°C for 3 hours.

As shown in Table 1, the amount of Dy2O3 added is 0, . 00
When the temperature exceeds 6'B, SrTiO3 becomes a solid solution in the crystal lattice mainly composed of SrTiO3 during sintering, and the specific resistance of the sintered body is reduced to 1. Since it can be lowered after OQ-cln@, it can be used as a varistor by re-firing in air. However, Dy2O3 is 10.000
If it exceeds the molten limit, it will no longer form a solid solution, and the resistivity of the sintered body will become low, making it unsuitable for use as a varistor.

During firing, BaO dissolves into crystals mainly composed of 5rT103 or segregates at grain boundaries of the crystals, increasing the resistivity of the grain boundary layer and increasing the nonlinearity of the sintered body. This effect appears when the amount of BaO added is 0.00.
This is when it reaches 6 moles or more. Furthermore, when the amount of BaO added exceeds 10,000 molar ratio, the dielectric loss angle tan δ increases, the dielectric constant ε gradually decreases, and the nonlinear index α also decreases.

In addition, the varistor voltage per unit thickness (1 mA/mm
) becomes a large value when Dy2O3 is less than 0.006 molar ratio because the specific resistance of the sintered body is large. Furthermore, BaO
Since S r T x O3 is solidly dissolved in the crystal, the variable voltage (1 mp, /ran) generally decreases when BaO is added.

Therefore, the range that satisfies both the functions of a varistor and a capacitor at the same time is Dy2030. Oo6-10, OOO mol%, Bao, oo6-10.000 mol%.

<Example 2> S r TiO3, Dy2O3, and CeO2 were made into the composition ratios shown in Table 2 below, mixed, molded, and fired in the same manner as in Example 1 above, and measured under the same conditions. The results are shown in Table 2.

As shown in Table 2 in the margin below, the addition amount of Dy2Q3 is 0.005
It contributes to lowering the resistivity of the sintered body in the range of ~10,000 molty, and can be used as a varistor by re-firing in air.

During firing, CeO segregates at the grain boundaries of crystals mainly composed of Sr 'f' 10 s, increases the resistivity of the grain boundary layer, and contributes to increasing the nonlinearity of the sintered body. This effect appears when the amount of CeO2 added is 0.005 mol or more, as is clear from the sudden increase in the nonlinear index a. Furthermore, the amount of CeO2 added was 10.
When the molar coefficient OOo is exceeded, the dielectric loss angle tan δ increases,
The dielectric constant ε gradually decreases, and the nonlinear index a also decreases.

Further, the varistor voltage per unit thickness (1 mA/cm) becomes a large value when Dy2O3 is less than 0.006 mol% because the specific resistance of the sintered body is large. Furthermore, CeO2
is partially dissolved in the SrTiO3 crystal,
/wn generally decreases when CeO2 is added.

Therefore, the range that satisfies both the functions of a varistor and a capacitor at the same time is Dy203o, Qo5~10.00o.
Mol%, CeO20, oo6-10. Ooo is in charge of mole.

In addition, in Examples 1 and 2, the case where only B a O and Ce O2 were used alone was explained,
Instead of these, Na, Ca, Cd, In, and Pb.

It has been confirmed that similar effects can be obtained even when each of the oxides of Aq is used alone within the above-mentioned predetermined amount range.

In addition, to these Ba, Ce, Na, Ca, Cd, In
, Pb.

It has been confirmed that similar effects can be obtained even when two or more Aq oxides are used, with the total addition amount falling within the above-mentioned predetermined amount range.

Create a circuit as shown in Figure 4 using the above elements,
As a result of examining the output situation with respect to the noise input A shown in FIG. 6, it was possible to suppress the noise as shown in the output situation curve B in FIG.

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

Note that the output situation of the conventional filter circuit shown in FIG. 1 is the same as the output situation curve C in FIG. 6, and noise is not removed sufficiently. Further, the conventional filter circuit including the varistor shown in FIG. 2 can obtain an effect similar to the circuit shown in FIG. .

Effects of the Invention As described above, the element using the ceramic composition according to the present invention has an unprecedented composite function and can play the roles of a varistor and a capacitor at the same time. It simplifies, contributes to miniaturization, high performance, and low cost, and absorbs surges in various electrical and electronic devices.

The application can be expanded 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
5 Figure 2 Figure 3 Figure 84 Figure 5 = Peripheral liquid number (bar H

Claims (1)

[Claims] 80.000 to 99.990 mol% of S r T 103, Dy2O3 as a metal oxide for promoting semiconductor formation
0.005 to 10.000 mo/I/%, Na, Ca, Cd, In, Ea. At least one element selected from the group consisting of Pb, Ag, and Ce in the form of an oxide of 0.006 to 10
．． 1. A voltage-dependent nonlinear resistor ceramic composition characterized in that it contains 0.000 molar fraction.