JPS6179202A - Manufacture of voltage dependent non-linear resistor ceramiccomposition - 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 Field of Industrial Application The present invention is applicable to voltage-dependent nonlinear resistors (hereinafter referred to as varistors) used for abnormal voltage absorption and noise removal in various electrical and electronic devices. The present invention relates to a method for producing 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 and ZnO-based varistors, which have voltage-dependent nonlinear resistance characteristics 2.\, have been used to eliminate sparks. The voltage-current characteristics of such a varistor can be approximately expressed as follows.

I-(V/C)c' Here, E is the current, ■ is the voltage, C is a constant specific to the varistor, and α is the voltage nonlinear index.

The α of SiC varistors is around 2 to 7, while the α of ZnO-based varistors (some risky ones have α as high as 60).Such varistors have excellent performance in absorbing relatively high voltages such as surges. However, due to its low dielectric constant and small specific capacitance, it has little effect on absorption of low voltages below the varistor voltage (e.g. noise), and the dielectric loss angle (tan δ) is still only 5 to 10 inches. big.

On the other hand, in order to remove these noises, the apparent dielectric constant can be reduced to 5X 1 by appropriately selecting the composition and firing conditions.
Semiconductor ceramic capacitors of about 04 to 6×10 4 and mn δ of about 1% are used. However, if a current exceeding a certain level 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 components (e.g., coils) are usually used in combination for the purpose of absorbing surges and eliminating noise, and for example, noise filters. is structured 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.
2 is a capacitor and 3 is a varistor.

However, such a noise filter circuit has the disadvantage that it increases the number of parts inside the device and is contrary to the trend toward miniaturization of devices.

Therefore, in recent years, a voltage-dependent nonlinear resistor porcelain set with a high dielectric constant has been developed. This is 5rTi○3
It contains Nb2O5 etc. as a metal oxide for promoting -'1!1 formation, and contains several types of metal oxides as nonlinearity promoters, and has both functions as a capacitor harristor. It has the same properties as a noise filter circuit. However, the manufacturing method used was to mix the additives with the main raw materials in advance and then perform reduction firing, followed by oxidation firing in the air, but this method requires a relatively high varistor voltage and a nonlinear index. The drawback was that it was rather small.

Purpose of the Invention In view of the above drawbacks, the present invention provides a method for producing a voltage-dependent nonlinear resistor ceramic composition that has both the functions of a varistor and a capacitor, has a low varistor voltage, and has a large nonlinear index. This is the Li-type.

Structure of the Invention In order to achieve the above-mentioned characteristics of the wooden BIJ, in the present invention, N is added to the sintered body mainly composed of 5rT103.
a.

A voltage-dependent nonlinear resistor coated with at least one monovalent element of K, Li, and Ag, heat treated in air at 900 to 1300°C, and diffused into the above-mentioned sintered body. A method for manufacturing a porcelain composition is provided.

Description of examples The present invention will be specifically explained below by giving examples.

5rTi○399.7 mol% and Nb2O50,3
mol was mixed wet for 20 hours using a ball mill etc., dried, 10 wt% of an organic binder (e.g. polyvinyl alcohol) was added and granulated.
−)φ×1. ○(-)1 shape with breath pressure 1, ○t/
Pressure molded with crl. This molded body was placed in the air at 1200°C.
After calcination at ℃ for 2 hours, a reducing atmosphere such as N2:N2
-10=1) at 1300 to 1450°C for 1 to 6 hours. The specific resistance of the sintered body thus obtained is 0.1 to 0.
．． The average particle diameter was 20 to 50 μm at 8Ω·α. Next, a paste containing a monovalent element was applied to both sides of this sintered body by screen printing or the like and dried. Paste is 1
For valence element oxide 0.1-2.09, ethyl cellulose 0.5-2.0g, carpitol acetate-1-6-4
It was made by mixing at a ratio of 0ml. Next, it was fired in air at 900 to 1300°C for 2 hours to obtain the sintered body 4 shown in FIG. Further, electrodes 5 and 6 were formed using a conductive material such as Aq. The diameter of the above electrodes 6, 6 is 6.0 (na)
It was set as φ.

The characteristics of the device thus obtained are also shown in the table below. Sample/J29 is 5rTi○399.7m01% and Nb
2O, 0.3 mol %, sample A 30 is 5rTi○
399.4 mol% to Nb2050.3 mo
%, Co2030, 3 mol fy was reduced and calcined in the same manner as above, and then heated to 1100°C in air.
The electrode (6,
0(-)φ).

Go to blank 7 below - Go to 9 - 7 Here, the characteristic evaluation of the element as a varistor is performed using the voltage-current characteristic formula % formula described above. α is a non-linear index) and C can be used. However, since accurate measurement of C is difficult, in the present invention, the varistor voltage per unit thickness when a varistor current of 1 mA flows (hereinafter v1 mA//+l
+I+) and α-17log (■1゜mA/
(1r11A) (where vlomA is the varistor voltage when a varistor current of 10 mA is applied) to evaluate the characteristics as a varistor.

In addition, the characteristic evaluation as a capacitor is performed at a measurement frequency of 1kHz2.
The dielectric constant is ε, and the dielectric loss angle tanδ is used.

According to the table, if the heat treatment temperature is lower than 9o○℃, α
is small and -δ becomes large, and if it is higher than 1300℃,
Since ε becomes smaller and VlmA/mm becomes larger, the temperature of the heat treatment is preferably 900 to 1300°C.

Also, if no diffusing agent is applied, V1mA/mm
becomes large and α becomes small.

As described above, according to this embodiment, the monovalent elements Na, Li, and Sr are added to the sintered body mainly composed of SrTiO2.

Apply at least one type of Aq and apply 900~
By heat-treating in air at 1300° C., it is possible to obtain a voltage-dependent nonlinear resistor ceramic composition that functions as both a varistor and a capacitor, has a low varistor voltage, and has a high nonlinear index.

As shown in FIG. 5, in the conventional filter circuit, the output situation curve C is obtained for the noise input A, and the noise is not removed sufficiently. Although the filter circuit including the conventional varistor shown in FIG. 2 can provide effects similar to those obtained using the element according to the present invention, it requires a separate varistor and requires a large number of components.

Therefore, when a noise filter circuit as shown in FIG. 4 was made using the element 7 according to the present invention and the coil 8,
The output situation curve B for the noise input A was obtained, and the noise could be sufficiently suppressed.

11 A-> Note that in the above examples, Na is used as the monovalent element.

Although only oxides of K, Li, and Ag were shown, it was confirmed that any other forms such as carbonates and fluorides have similar effects.

Further, in the above example, only one type of monovalent element was used, but it was confirmed that the same effect can be obtained even if multiple types are used.

Effects of the Invention As described above, the present invention includes monovalent elements Na, K, Li,
By coating at least one type of Ag and heat-treating it in air at 900 to 1300°C, it has both varistor and capacitor functions, and has a low varistor voltage and a high non-linearity index. A nonlinear resistive ceramic composition can be obtained, which has great practical effects.

[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 filter circuit, and is a characteristic diagram showing input noise and output noise situations by the noise filter circuit of the present invention and the conventional noise filter circuit. 4... Sintered body, 6, 6... Electrode, 7.
...Element, 8...Coil. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3, Figure 5 → Peripheral frequency (MHz)

Claims (1)

[Claims] Na, K, and L are added to the sintered body whose main component is SrTiO_3.
i. A voltage-dependent nonlinear resistor ceramic composition characterized in that at least one monovalent element of Ag is coated, heat treated in air at 900 to 1300°C, and diffused into the sintered body. Production method.