JPS59208807A - Voltage dependency 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 Conventionally, SiC Balinulis has voltage-dependent nonlinear resistance characteristics for absorbing abnormally high voltages (hereinafter referred to as surges) in various electrical and electronic devices, removing noise, extinguishing sparks, etc. ZnO-based Balinuku etc. were used. The voltage-current characteristics of such a varistor can be approximately expressed as follows.

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

SICIC varistors are about 2N7, and ZnO-based varistors can be up to 5o. 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 almost no effect on the absorption of the dielectric loss angle (t
anδ) is also large, at a factor of 5 to 10.

On the other hand, in order to remove these noises, the apparent dielectric constant can be reduced to 5×10 by appropriately selecting the composition and firing conditions.
Semiconductor ceramic capacitors with a size of about 4 to 6×10 4 and a tan δ of about 1% are used. However, this semiconductor ceramic capacitor broke down when a current exceeding a certain limit was applied to the element due to a surge, etc., and it no longer functioned as a capacitor.

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

Fig. 1 shows a general conventional noise filter circuit, and Fig. 2 shows a conventional noise filter circuit configured by combining a varistor, a capacitor, and a coil.
Koinobe 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.Secondly, 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.

Arrangement of the Invention To achieve this object, the present invention provides Sr Ti 03
and a trace amount of Nb2O5 that is present in the raw material from the beginning,
Ta205, Mg,
The present invention aims to obtain a voltage-dependent nonlinear resistor ceramic composition containing a predetermined amount of at least one element selected from the group consisting of Zr, Sn, Sb, W, and Bi.

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

<Example> 5rTiOs and a trace amount of N present in the raw material from the beginning
b2O5 (Nb2O5 content in the raw material used in this example is 0.050 (:/l/%), Ta205 as a metal oxide for promoting semiconductor formation, and ZrO2 as an element for improving nonlinearity as shown below) After weighing so as to have the composition ratio shown in Table 1, it was mixed and ground in a ball mill for 6 hours, dried, and then heated for 1000' in air.
C. Calcinate for 14 hours. After that, it was wet-pulverized for 4 hours using ball milli/l/, etc., dried, and an organic binder (for example, polyvinyl alcohol) was added in Swt% and granulated.8. ○φ(υ・5)×10t(yra)
It was molded into a disk shape at a molding pressure of about 1.0 y2 and a force of 1 pressure m. This molded body is placed in a reducing atmosphere (for example, N2H2:
1; 1, flow rate ""An) at 1350℃ at 4 hours f7
J1 fired. The fired body thus obtained had an average specific resistance of 0.3Ω, and an average particle size of 30 μm.

Next, the above-mentioned sintered body was fired in air at 1300° C. for 2 hours to obtain the sintered body 4 shown in FIG. 3. Furthermore, both planes of the sintered body 4 are polished using an abrasive such as SiC, and A
Using conductive metal such as q,
6. The shape of the electrodes 5 and 6 was a circle of 5·Qφ(N4).

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

Note that the 4-1 property evaluation of the element as a varistor is performed using the above-mentioned voltage-current characteristic formula % formula (%) (where ■ is current, ■ is voltage, C is a constant unique to Varistor, and α is a nonlinear index. ) can be done by α and C in ).

However, C. Since the Δ11j constant which is exactly (tt') is a river cicada, in Mokubudame, the varistor voltage per unit thickness when a current of 1 mA flows (hereinafter referred to as ""/yttyn.
) and α−1/β. g (v10mA/v1mA) (However, V+
omA is the varistor voltage when passing a current of 10 mA, V
+ mA is the varistor voltage when a current of 1 mA flows. ) The characteristics as a varistor are evaluated based on the value. In addition, the characteristic evaluation as a capacitor is performed at the measurement frequency I
This is performed using a dielectric constant ε and a dielectric loss angle −δ in KIIZ.

As shown in Table 1, the addition amount of Ta205 is 0.00.
If it exceeds 5 mol%, it will form a solid solution in the lattice of the crystal mainly composed of SrTi03 during firing, and the specific resistance of the sintered body can be lowered to around 1.0 Ω■ by controlling the valence.
By re-firing in air, a high resistance is formed at the grain boundaries of the sintered body, making it possible to use it as a varistor. However, if T2L205 exceeds 10,000 mo/V%, it will no longer form a solid solution, and the resistivity of the sintered body will increase, making it unsuitable for use as a varistor.

In addition, Nb2O5 is mixed and contained in TiO2 in the raw material, and although it was not intentionally added as an additive, the presence of Nb2O5 does not inhibit υ semiconductor formation. Therefore, TlO2 as a raw material may be used in a crumbled state containing Nb2O5 without being purified to high purity. Note that the content of Nb2O5 is TiO
Although it differs depending on the purification purity of
is contained, so the Nb2O5 content is o, ○o1~
012oo-1:) v%.

ZrO2 segregates at grain boundaries of crystals mainly composed of SrTiO3 during firing, increases the resistivity at the grain boundaries, and contributes to thickening the nonlinear index α of the sintered body.

This effect appears when ZrO2 is added 11 (
is ○, ○05 mo/l/% or more. Also,
7 when the amount of ZrO2 added exceeds 10.000v%
L characteristics are deteriorating.

Therefore, the composition range that satisfies both the functions of a varistor and a capacitor is T2L205 of 0.005 to 10.
000 moles, ZrO2 is O2O35~10.00
It is 0 moles. In addition, test width 1~5゜10.11,
16, 1, 22, 23, and 28 to 34 are comparative examples.

In addition, in the example, the case where only ZrO2 is used in iJj Germany was explained, but instead of these, Mg,
It has been confirmed that similar effects can be obtained even when Sn, sb, w, and Bi minides are used individually within the above-mentioned prescribed amounts. Moreover, these Zr, Mq.

It has been confirmed that similar effects can be obtained even when two or more types of oxides of Sn, Sb, Vl, and Bi 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.
As a result of examining the output situation using noise as shown in FIG. 5, it was possible to suppress the noise as shown in 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 condition of the conventional fill circuit shown in FIG. 1 is as shown by the output condition curve C in FIG. 5, and noise is not removed sufficiently. Further, the conventional fill circuit including the varistor shown in FIG. 2 can obtain an effect similar to the circuit shown in FIG. Become.

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

It can be extended to noise removal, and its practical value is extremely high.

[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. 5 is a circuit diagram showing a fill circuit, and is a characteristic diagram showing the input noise and output noise states of the present invention and the conventional noise fill circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Figure 5 Kl '*l':, kuosttz)

Claims (1)

[Claims] Sr Ti Os 99-989 Hair 9.800-
E-/L/%. N1) 205 from 0.001 to 0.200 mo/lz
%, T112 03 0.00 5~1 0.0
00Mo/L'%, Mg, Zr. At least one element selected from Sn, Sb, W, and Bi in the form of an oxide.・00
A voltage-dependent nonlinear resistor ceramic composition characterized in that it contains 5 to 10,000 moles.