JPS59147406A - 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. This relates to a voltage-dependent nonlinear resistor ceramic composition suitable for Removal.

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: 0 I-(V/C)(L where ■ is the current, ■ is the voltage, and C is a constant specific to the varistor. 03iC varistors have α of 2 to 7, and some ZnO-based varistors have α as high as 60.Such varistors are difficult to absorb relatively high voltages such as surges. Although it has excellent performance, it has a low dielectric constant and a small specific capacitance, so it has little effect on absorbing low voltages below the varistor voltage (for example, noise), and it also has low dielectric loss (t , anδ) is also 6
It is as large as ~10%.

On the other hand, to remove these noises, the apparent dielectric constant can be reduced to 5X10 by appropriately selecting the composition and firing conditions.
Semiconductor ceramic capacitors with a tan δ of about 1 inch are used. However, if a current exceeding a certain limit is applied to the element due to a surge or the like, this semiconductor ceramic capacitor will be destroyed or will no longer function as a capacitor.

For the reasons mentioned above, in electrical and electronic equipment, varistors, capacitors, and other parts (e.g. coils) are usually used in combination 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 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 objectives, the present invention has the following five points:
rT103 and Dy2 as a metal oxide for promoting semiconductor formation.
O3, Mg, Zr, Sn, Sb, W, Bi, Ni.

DESCRIPTION OF EMBODIMENTS The present invention will be described in detail below by way of example. Please explain in detail.

<Example 1> 5rTiO, Dy2O3, and ZrO2 were weighed out so as to have the composition ratio shown in Table 1 below, and then mixed wet for 6 hours using a ball mill or the like, dried, and then mixed in air. Calcinate at 1000-1250°C for 21-5 hours.

After that, it 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).
φx1. Pressing pressure 1.0 into the shape of O' (mm) t
//Pressure molded with c11+. This molded body is heated to 1300-145 in a reducing atmosphere (for example, N2:N2-10:1).
It was fired for 1-6 hours. The specific resistance of the fired body thus obtained is 0.1-0.8Ω, Cm, and the average grain size is 20~
It was 60 IIη. Next, this fired body was placed in the air for 1
The sintered body 4 shown in Fig. 3 was obtained by firing at oOO~1300''C for 0.6~5 hours.
After polishing with an abrasive such as iC, electrodes 5 and 6 were formed using a conductive metal such as Aq. The diameter of the electrode 5°6 is 5.
It was set to 0 (mm)φ.

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

Margin below Here, the characteristic evaluation of the element as a varistor is α in the electric IF-current characteristic formula % formula % (where ■ is the current, ■ is the voltage, C is a constant unique to the varistor, and α is a nonlinear index). This can be done by and C. However, since accurate measurement of C is difficult, in the present invention, the varistor voltage per unit thickness (hereinafter referred to as v1rr1A
/mm) and the value of a-1/b sail■1or11A/
The characteristics of the varistor are evaluated based on the value of 1mA) (where 1omA is the varistor voltage when the full varistor current of 1omA flows, and vlmA is the varistor voltage when the varistor current of 1mA is passed). In addition, the characteristics of the capacitor are evaluated using a measurement frequency of 1 kt (L), a dielectric constant ε, and a dielectric loss angle δ.
, 2 hours, firing temperature in air 9 hours at 1200℃
, which took 3 hours.

As shown in Table 1, the addition amount of Dy2o3 is 0.005
If the temperature exceeds molten metal, SrTiO3 will form a solid solution in the lattice of the living crystal during firing, and the resistivity of the sintered body can be lowered to around 1.0Ω, cm by controlling the valence, so re-firing in air is necessary. This makes it possible to use it as a varistor. But 1. When Dy2O3 exceeds a molar ratio of 10,000, it no longer forms a solid solution, and the specific resistance of the sintered body increases, making it unsuitable for use as a varistor.

During firing, Z r O2 segregates at the grain boundaries of crystals made of S r TiO3 as a living body, increases the specific resistance of the grain boundary layer, and contributes to increasing the nonlinearity of the sintered body.

This effect is enhanced when the amount of Z r O2 added is 0. ○This is when it reaches 5 moles or more. Still, Z
When the amount of r O2 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.

Also, the varistor voltage per unit thickness (■1mA/fnm
) becomes a large value when Dy2O3 is less than 0.005 molar ratio because the resistivity of the sintered body is large. Furthermore, D.Y.
As the amount of O and Z r O2 added increases, the specific resistance of the sintered body increases, so 1rnA/mm generally becomes a large value.

Therefore, the range that satisfies both the functions of a varistor and a capacitor at the same time is Dy2030.0O5 to 10.000%.
ZrO20,005-10,000 mol%.

<Example 2> S r T 103, Dy2O3 and NiO were combined into the following second
Table 2 shows the results of mixing, molding and firing in the same manner as in Example 1, using the composition ratios shown in the table, and measuring under the same conditions.

As shown in Table 2, the amount of Dy2O3 added is o, oos.
It contributes to lowering the specific resistance of the sintered body in the range of ~10.000 mol %, and can be used as a varistor by re-firing in air.

During sintering, N i O dissolves in the crystal containing S r T 103 as a living body or segregates at the grain boundaries, increasing the resistivity of the grain boundary layer and increasing the nonlinearity of the sintered body. Contribute to This effect appears when the amount of NiO added is 0.
．． This is clear from the fact that the nonlinear index α suddenly increases when the amount exceeds 0.005 mol %.

Indeed, when the amount of N i O added exceeds 10.000 mol %, the dielectric loss angle tan δ increases, the dielectric constant ε gradually decreases, the nonlinear index α also decreases, and the characteristics deteriorate.

Also, the varistor voltage per unit thickness (■1mA//mm
) becomes a large value when Dy2o3 is less than 0.005 mol% because the specific resistance of the sintered body is large. Furthermore, NiO
When the amount of addition is small, some solid solution is observed in the crystals,
The varistor voltage (v1mA/iT1m) decreases.

Therefore, the range that satisfies both the functions of a varistor and a capacitor at the same time is Dy2030.005 to 10.000%.
Ni is 00.005 to 10.000 mol%.

In addition, in Examples 1 and 2, the case where ZrO2 and NlO were used alone was explained, but instead of these, oxides of Mg, Sn, Sb, W, Bi, and Fe were used in n alone. It was confirmed that similar effects can be obtained even when used within the above-mentioned predetermined amount range. In addition, these Zr, Ni,
It has been confirmed that similar effects can be obtained even when two or more types of oxides of Mg, Sn, Sb, W, Bi, and Fe are used in such a manner that the total amount added falls within the above-mentioned predetermined amount range.

Create a circuit as shown in Figure 4 using the above elements,
The output situation was examined for the noise input A shown in FIG. 5, and the noise could be suppressed as shown in the output situation curve B in FIG.

In FIG. 5, 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 in the output state of mixed oil @C in FIG. 5, and noise is not sufficiently removed. 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 and contributes to miniaturization, high performance, and low cost, and it 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 circuit diagram showing the element shown in Figure 3. FIG. 6 is a circuit diagram showing a noise filter circuit according to the present invention and a characteristic diagram showing the state of human noise and output noise in the noise filter circuit of the present invention and the conventional noise filter circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 A 14 Figure 5 I 7ifJ number (r'1F11) 34-

Claims (1)

[Claims] 80.000-99,990 mol% of 5iTiO and 0.00% of Dy2O3 as a metal oxide for promoting semiconductor formation.
5-10.000 Mo/I/%, Mg, Zr, Sn,
Sb, W, Ei. At least one element selected from the group consisting of Ni and Fe in the form of an oxide of 0.006 to 10.00
A voltage-dependent nonlinear resistor ceramic composition characterized by containing 0 molti.