JPH10312909A - Method of manufacturing voltage non-linear resistor for low voltage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a voltage non-linear resistor for a low voltage having a varistor voltage of 20 V or less and an excellent voltage non-linear coefficient with a voltage non-linear resistor mainly composed of zinc oxide. The aim is to provide a method. SOLUTION: A composition obtained by further adding tellurium to a composition containing at least bismuth, cobalt, manganese, antimony and titanium as accessory components to zinc oxide as a main component,
During firing, the rate of temperature rise in a temperature range higher than 700 ° C. is controlled, and the sintering temperature is also set to 1200 ° C. or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a low-voltage non-linear resistor mainly composed of zinc oxide.

[0002]

2. Description of the Related Art A conventional method for manufacturing a voltage non-linear resistor is based on a method in which zinc oxide as a main component and Bi ₂ O ₃ ,
Various metal oxides such as o ₃ O ₄ , MnO ₂ , Sb ₂ O ₃ , and TiO ₂ are weighed in predetermined amounts, mixed and granulated to form a granulated powder into a predetermined shape. Generally, a method is used in which an electrode is formed after the temperature is raised at a rate of up to 300 ° C. and baked at a temperature of 100 to 1300 ° C. The varistor voltage of the voltage non-linear resistor obtained in this manner (V _{1 mA}
/ Mm) can be arbitrarily changed depending on the kind and the added amount of the subcomponent, but generally the minimum is about 20V. However, in recent years, the circuit voltage has been reduced due to the reduction in the voltage of semiconductors and the like, and accordingly, the reduction in the voltage of the voltage non-linear resistor has been required, and the varistor voltage (V _{1 mA} / mm) has been reduced to 2 V.
It is necessary to reduce the voltage to 0 V or less. To meet this demand, a method of adjusting the varistor voltage by reducing the thickness of the voltage non-linear resistor has been generally performed.

[0003]

However, in the above-mentioned conventional method, when the thickness of the voltage non-linear resistor is reduced, the mechanical strength is reduced, which may cause a trouble in an assembling process, or may reduce the reliability of the product. It had an effect on gender.

An object of the present invention is to solve the conventional problems and to provide a method for manufacturing a low-voltage voltage non-linear resistor having high reliability and preventing a process trouble. .

[0005]

According to the present invention, at least bismuth, cobalt, manganese, antimony, and titanium are added as auxiliary components to zinc oxide as a main component in a predetermined amount, and tellurium is further added. A molded article having a composition of 0.05 to 1.00 mol% in terms of TeO ₂ is added,
The temperature is raised at a rate of 50 to 150 ° C. per hour in a temperature range higher than 700 ° C. and firing is performed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is characterized in that at least bismuth, cobalt, manganese, antimony and titanium are added to zinc oxide as a main component and Bi ₂ O ₃ and Co ₃ O ₄ as subcomponents, respectively. , MnO ₂ , Sb ₂ O ₃ , TiO ₂
In terms of, Bi ₂ O _{3; 0.10~2.00} mol% Co ₃ O _4; 0.10~1.00 mol% MnO _2; 0.10 to 2.00 mol% Sb ₂ O _3; 0.01-0.20 mol% TiO _2; adding 0.10 to 2.00 mol%, 0.05 in terms further tellurium TeO ₂
A molded body having a composition of 1.00 mol% added is fired by increasing the temperature in a temperature range higher than 700 ° C. at a rate of 50 to 150 ° C./hour. This makes it possible to make the thickness of the voltage non-linear resistor 1 mm or more, prevent troubles in the assembling process, and improve the reliability of the product.

[0007] The invention according to claim 2 of the present invention is a production method in which the composition according to claim 1 is fired at a temperature of 1000 to 1200 ° C. Te added in this firing temperature range
O ₂ promotes the grain growth of the voltage non-linear resistor, and at the same time, lowers the firing temperature to suppress the evaporation of Bi ₂ O ₃ and prevent the performance of the voltage non-linear resistor from deteriorating. it can.

Hereinafter, an embodiment of the present invention will be described. (Embodiment 1) FIG. 1 is a firing shrinkage curve of a voltage nonlinear resistor having a composition of this embodiment.

First, bismuth oxide is added to the main component zinc oxide,
Cobalt oxide, manganese oxide, antimony oxide, titanium oxide, and tellurium oxide were each weighed to have the composition shown in (Table 1).

[0010]

[Table 1]

Pure water and a polyvinyl alcohol solution were added to the raw materials, mixed for 24 hours by a ball mill, and the slurry was dried and granulated by a spray drier. The obtained granulated powder is 800 kg / cm in a disc shape having a diameter of 13 mm and a thickness of 1.2 mm.
Molding was performed at a molding pressure of ² . This compact was placed in an alumina porcelain container and fired. Under these conditions, the temperature was raised at a rate of 100 ° C./hour from room temperature to 700 ° C., and in the temperature range over that, the temperature was raised at the rate shown in (Table 1). After the temperature was maintained for 2 hours, the temperature was lowered at a rate of 100 ° C./hour. A silver electrode paste was printed on both sides of the thus obtained sintered body, and baked at a temperature of 600 ° C. to form an electrode. After measuring the varistor voltage for each of the 30 samples prepared as described above, the voltage nonlinear coefficient (α) was calculated, and the average value of the characteristic measurement results is shown in Table 1. The varistor voltage indicates the voltage value when a current of 1 _mA flows, and the voltage nonlinear coefficient is

[0012]

[Outside 1]

Calculated from (Equation 1) from the voltage value at the time when each current was passed.

[0014]

(Equation 1)

As is clear from Table 1, Sample No. 1 containing less than 0.1 mol% of bismuth oxide, 2.0 mol%
More sample No. 5 composition, sample No. 6 with less than 0.1 mol% cobalt oxide, sample N with more than 1.0 mol%
o9, sample No. in which manganese oxide is less than 0.1 mol%
Sample No. 13 with more than 10, 2.0 mol%, Sample No. 14, 0.2 with less than 0.01 mol% of antimony oxide
Sample No. 17 containing more than 0 mol%, sample No. 18 containing less than 0.1 mol% of titanium oxide, sample No. 21 containing more than 2.0 mol%, and sample Nos. 22, 23 and 1.0 containing less than 0.05 mol% of tellurium oxide Sample No. more than mol%
In any case, the composition of No. 26 has a high varistor voltage of 20 V or more. On the other hand, Sample Nos. 2, 3, and 4 containing bismuth oxide of 0.1 to 2.0 mol% and cobalt oxide of 0.1 to 2.0 mol%
1.0 mol% of sample Nos. 7 and 8, manganese oxide was 0.1%
Sample Nos. 11 and 12 of 0.1 to 2.0%, Samples 15 and 16 of 0.01 to 0.2 mol% of antimony oxide, and Samples N.I. of 0.1 to 2.0 mol% of titanium oxide. 19, 20, sample No. 24 in which tellurium oxide is 0.05 to 1.00 mol%,
It can be seen that the varistor voltage was lower than 20 V in each of the 25 compositions. This means that the varistor voltage is reduced, that is, the composition of bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, and titanium oxide is added to the grain growth of the zinc oxide sintered particles, and further, tellurium oxide is added to 0.05 to 1%.
It suggests that the addition of mol% contributes greatly.

Regarding the firing conditions, when the heating rate is high, Sample Nos. 29 and 32 are sample No.
The varistor voltage exceeds 20 V despite being the same as 3, 27, 28, 31. On the other hand, the sample No.
Numeral 27 indicates a low varistor voltage of 11V. As shown in FIG. 1, shrinkage starts sharply at around 700 ° C. and ends at around 1200 ° C. During the shrinkage process, the movement and diffusion of the additive component proceed, and crystal grain growth occurs. In order to reduce the varistor voltage, it is necessary to increase the size of the zinc oxide sintered particles.If the rate of temperature increase during the shrinkage process is high, the zinc oxide sintered particles can be sufficiently controlled even when the additive composition is controlled. It is thought that the growth of GaN cannot be promoted, and as a result, the varistor voltage increases.

In the case of the highest temperature during firing, the sample N
When o3, 30, and 31 are compared, although the composition is the same, the varistor voltage of sample No. 30 exceeding 1200 ° C. is 20 V or less, but the voltage nonlinear coefficient α is extremely small. This is presumably because the low-melting-point oxide bismuth oxide added as a sub-component had an increased amount of evaporation when fired at 1300 ° C. at a high temperature.

From these results, in order to obtain a voltage nonlinear resistor having a varistor voltage of 20 V or less and an excellent voltage nonlinear coefficient α, bismuth oxide, cobalt oxide, manganese oxide, antimony oxide And 0.05 to 1 mol% of tellurium oxide is further added to titanium oxide, and the temperature is raised in a temperature range higher than 700 ° C. at a rate of 50 to 150 ° C./hour, and the maximum temperature is also in the range of 1000 to 1200 ° C. It turns out that it is necessary to fire at the temperature. This allows the varistor voltage to be 20 V even if the voltage non-linear resistor is 1 mm or more.
It becomes the following and process troubles can be eliminated.

An additive for further improving the varistor characteristics;
For example, it has been confirmed that the same effect as described above can be obtained also with a composition in which chromium oxide, nickel oxide, silicon oxide, boron oxide, aluminum, glass powder, and the like are added in appropriate amounts. Further, the temperature was raised in a temperature range higher than 700 ° C. at a rate of 50 to 150 ° C. per hour. However, it is possible to lower the temperature rising rate below 50 ° C. The heating rate was outside the scope of the claims.

[0020]

As described above, according to the present invention, at least bismuth, cobalt, manganese, antimony and titanium are added to zinc oxide as a main component and Bi ₂ O ₃ and
₃ O ₄ , MnO ₂ , Sb ₂ O ₃ and TiO ₂ , respectively, Bi ₂ O ₃ ; 0.10 to 2.00 mol% Co ₃ O ₄ ; 0.10 to 1.00 mol% MnO ₂ ; 0.10 to 2.00 mol% Sb ₂ O _3; 0.01 to 0.20 mol% TiO _2; to 0.10 to 2.00 mol% the added composition, further in terms of tellurium to TeO ₂ 0.
A molded article having a composition of 0.05 to 1.00 mol%
The temperature range higher than 50 ° C./hour is raised at a rate of 50 to 150 ° C./hour, and the firing is performed at a temperature in the range of 1000 to 1200 ° C., so that the varistor voltage is 20 V or less and the voltage nonlinearity is excellent. It becomes possible to manufacture a linear resistor.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a firing temperature and a contraction rate of a voltage nonlinear resistor.

Claims (2)

[Claims] At least bismuth, cobalt, manganese, antimony, and titanium are added to zinc oxide as a main component as an auxiliary component, respectively, as Bi ₂ O ₃ , Co ₃ O ₄ , MnO ₂ , and Sb ₂ O.
₃ , in terms of TiO ₂ , Bi ₂ O ₃ ; 0.10 to 2.00 mol% Co ₃ O ₄ ; 0.10 to 1.00 mol% MnO ₂ ; 0.10 to 2.00 mol% Sb ₂ O ₃ ; 0.01 to 0.20 mol% TiO ₂ ; 0.10 to 2.00 mol%, and further, tellurium is converted to TeO ₂ and 0.05 to 0.20 mol%.
A method for producing a voltage non-linear resistor for a low voltage, comprising firing a molded body having a composition containing 1.00 mol% at a temperature higher than 700 ° C. at a rate of 50 to 150 ° C./hour. Method. 2. The maximum temperature during firing is from 1000 to 1200.
2. The method according to claim 1, wherein the temperature is set to ° C.