JP2000226267A - Production of resistor with nonlinear voltage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject resistor through suppressing the rise of its production cost without deteriorating its characteristics by burning a specific molded form on a bottom board consisting mainly of MgAl2O4 spinel. SOLUTION: This resistor is obtained by the following process: ZnO as the main component is mixed with each 0.5-1.0 mol% of Bi2O3, Co3O4, MnO2, and Sb2O3 followed further mixing together with pure water in a ball mill; polyvinyl alcohol is then added to the resulting mixture followed by drying and granulation; the resultant granular powder is put to pressure molding to form a disk- shaped molded form 2. Subsequently, the molded form 2 is put on a bottom board 3 consisting mainly of MgAl2O4 spinel and placed in an Al2O3-based sagger 1 and then burned at about 1,150 deg.C in situ. Both sides of the resultant sintered compact are printed with silver electrode pastes, which are then baked at about 600 deg.C. The production method described above gives resistors with electrical properties kept intact even if the bottom board 3 is repeatedly used, wherein the impurity SiO2 content of the bottom board 3 is controlled pref. to <=0.5 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a voltage non-linear resistor mainly composed of ZnO.

[0002]

2. Description of the Related Art A conventional method for manufacturing a voltage non-linear resistor is based on the premise that ZnO is a main component and Bi ₂ O ₃ , Co is a sub-component.
A material powder to which various metal oxides such as ₃ O ₄ , MnO ₂ , Sb ₂ O _3, etc. are added is formed into a predetermined shape, and this is shaped into a material having a size of 1000 to 13.
After firing at 00 ° C., electrodes are formed on the surface of the sintered body to produce a voltage non-linear resistor. During this firing, as shown in FIG. 4, the sintering is carried out by putting it in a sheath 1 made of an inorganic refractory material, for example, Al ₂ O ₃ porcelain. Electrical characteristics deteriorate. In order to prevent this, a method in which the molded body 2 is placed on a floor plate 4 made of the same material as the molded body 2 and housed in the sheath 1 and fired is generally used.

[0003]

However, in the above-mentioned conventional method, when the base plate 4 of the same material as the molded body 2 is repeatedly used, the composition of the base plate 4 changes, and the voltage non-linear characteristic and the surge current of the sintered body are changed. The withstand capacity deteriorates. In order to prevent this, it is necessary to frequently replace the floor plate 4, which has a problem that the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention solves the conventional problems, and can suppress an increase in manufacturing cost without causing deterioration in characteristics of a voltage non-linear resistor even when a floor plate is repeatedly used during firing. It is an object of the present invention to provide a method for manufacturing a voltage non-linear resistor.

[0005]

In order to achieve the above object, the present invention provides a voltage non-linear resistor element containing ZnO as a main component and various metal oxides as subcomponents.
Because it is then burned by placing the ₂ O ₄ spinel in the floor plate mainly, according to this method, the reaction between the formed body and the floor plate is almost no change in composition of the sole plate does not occur even in repeated use, resulting It is possible to prevent the electrical characteristics of the sintered body from being deteriorated.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention relates to a voltage nonlinear resistor element containing ZnO as a main component and various metal oxides as subcomponents, and a MgAl ₂ O ₄ spinel. A method for producing a voltage non-linear resistor, characterized in that it is mounted on a sole plate as a main component and fired,
_{Since 2} O ₄ spinel hardly reacts with the voltage non-linear resistor element and is chemically stable, no composition change occurs even when repeatedly used for firing. For this reason, the obtained sintered body has an effect of suppressing deterioration of electric characteristics and providing a voltage non-linear resistor having stable electric characteristics.

According to a second aspect of the present invention, there is provided a method of manufacturing a voltage non-linear resistor according to the first aspect, wherein the base plate has an apparent porosity of 10% to 30%. In addition, by controlling the porosity of the bottom plate, cracking and deformation of the bottom plate during firing can be prevented, and the bottom plate can be used repeatedly for a long period of time.

According to a third aspect of the present invention, there is provided a voltage non-linear resistance according to the first aspect, wherein the sole plate is controlled to 0.5% or less of SiO ₂ contained as an impurity. It is a method of manufacturing a device, and by using a bottom plate with a small amount of SiO ₂ which easily reacts with zinc oxide as a main component, a reaction with a voltage non-linear resistor element can be further suppressed and deterioration of electric characteristics is small. This has the function of providing an excellent voltage non-linear resistor.

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing an embodiment of the present invention. In FIG. 1, 1 is an inorganic sheath, 2 is a molded body, and 3 is a sole plate mainly composed of MgAl ₂ O ₄ spinel.

First, 0.5 m of Bi ₂ O ₃ is added to the main component of ZnO.
ol%, 0.5 mol% of Co ₃ O ₄ and 0.5 mol of MnO ₂ .
mol% and 1.0 mol% of Sb ₂ O ₃ were weighed, and pure water was added thereto, mixed with a ball mill for 24 hours, added with 0.5% by weight of polyvinyl alcohol, and dried and produced with a spray drier. Granulated.

The obtained granulated powder is formed into a disk having a diameter of 16 mm and a thickness of 2 mm at a pressure of 800 kg / cm ² to obtain a molded body 2. Then, as shown in FIG. Al ₂ O ₃ is placed on a floor plate 3 mainly composed of ₂ O ₄ spinel.
It was stored in a quality sheath 1 and fired at a temperature of 1150 ° C. At this time, SiO ₂ as an impurity contained in the floor plate 3 is used.
Was controlled in the range of 0.1 to 1.0%. In addition, for comparison, baking was performed using a floor plate 4 made of the same material as the conventional molded body 2.

With respect to each of the obtained sintered bodies, a silver electrode paste was printed on both surfaces thereof and baked at a temperature of 600 ° C. to form electrodes, thereby producing a voltage non-linear resistor.

Each of the prepared samples is 1 m
A, a varistor voltage was measured when a current of 100 μA was passed, and a voltage nonlinear coefficient (α) was calculated using (Equation 1), and the number of times of repeated use of the floor plates 3 and 4 and the voltage nonlinear coefficient (α) Is shown in FIG. 2 and the current waveform of each sample is 8/2.
A surge current withstand test in which a surge current of 0 μs and a current value of 5000 A was applied 10 times was performed, and the relationship between the number of times of repeated use of the floor plates 3 and 4 and the surge current withstand is shown in FIG.

[0015]

(Equation 1)

As is apparent from FIG. 2, the MgA of the present invention is
In the case of using the base plate 3 containing l ₂ O ₄ spinel as a main component, the voltage nonlinear coefficient of the obtained voltage nonlinear resistor is not adversely affected even if the number of times of firing is repeatedly used. In the case where the amount of impurity SiO ₂ in the floor plate 3 is controlled to 0.5% or less, the influence is further reduced. On the other hand, the conventional molded body 2
It can be seen that when the soleplate 4 of the same material is used, the voltage nonlinear coefficient of the voltage nonlinear resistor decreases as the number of times of repeated use increases.

Next, referring to FIG. 3, when the soleplate 3 mainly composed of MgAl ₂ O ₄ spinel is used, the surge current withstand capability of the obtained voltage non-linear resistor can be improved even if the number of times of repeated use is increased. It can be seen that those having an adverse effect and controlling the amount of SiO ₂ to 0.5% or less further reduce the effect.

This is because, in the case of the conventional example, when the floor plate 4 is repeatedly used by firing, a part of the composition components evaporate and scatter to cause a change in the composition, and the atmosphere in the sheath 1 changes with the number of uses. It is thought that. On the other hand, the sole plate 3 of the present invention has high chemical stability, MgAl
_{Since 2} O ₄ spinel is the main component, the composition does not change even when repeatedly used for firing. Therefore, it is considered that the firing atmosphere became constant regardless of the number of times of use, and the electrical characteristics of the obtained voltage non-linear resistor were stabilized.

From the above, when the soleplate 3 containing MgAl ₂ O ₄ spinel as a main component is used, repeated use of the soleplate 3 does not adversely affect the electrical characteristics of the obtained voltage non-linear resistor. I understand. Further, it became clear that it was necessary to control the amount of SiO ₂ as an impurity contained in the floor plate 3 to 0.5% or less.

(Embodiment 2) A molded body 2 produced in the same manner as in Embodiment 1 was prepared by using MgA having an apparent porosity of 7 to 35%.
It is placed on a floor plate 3 mainly composed of l ₂ O ₄ spinel, stored in a sheath 1, and stored at 1100 ° C., 1200 ° C., and 1300 ° C.
Was fired at each temperature. In the present embodiment, a durability life test was performed by repeatedly using the floor plate 3 until the floor plate 3 was cracked or significantly deformed, and the results are shown in Table 1.

[0021]

[Table 1]

As is clear from Table 1, those having an apparent porosity of 7% or 35% of the flooring plate 3 cannot be used after being repeatedly used up to 10 times at each firing temperature because of cracking or deformation. On the other hand, when the apparent porosity is 10 to 30%,
It can be seen that when the sintering temperature is 1200 ° C. or less, it can withstand repeated use of 40 times or more. In addition, it is considered that when the apparent porosity is 7%, cracks are generated due to thermal stress in repeated use, and when the apparent porosity is 35%, the mechanical strength is weak and deformation occurs. On the other hand, when the sintering temperature is 1300 ° C., the reaction between the MgAl ₂ O ₄ spinel, which is a component of the bottom plate, and the molded body 2 of the voltage non-linear resistor occurs, and the life of the bottom plate 3 is reduced. Undesirably, the additive sub-components of the molded article 2 of the non-linear resistor evaporate and evaporate intensely, and the characteristics are significantly reduced.

From the above, by controlling the apparent porosity of the floor plate 3 to 10 to 30% and setting the firing temperature to 1200 ° C. or lower, the service life of the floor plate 3 can be extended. In the present invention, the sole plate 3 mainly containing MgAl ₂ O ₄ spinel is housed in the sheath 1, but the sheath 1 itself is made of MgAl ₂ O _4.
By using a material whose main component is ₂ O ₄ spinel,
Can be omitted.

[0024]

As described above, according to the present invention, it is possible to withstand repeated use of firing as a sole plate in firing a voltage nonlinear resistor molded body containing ZnO as a main component and various metal oxides as subcomponents, and MgAl ₂ that does not affect electrical properties
By using a sole plate containing O ₄ spinel as a main component, it is possible to provide a low-cost method of producing a voltage non-linear resistor excellent in voltage non-linearity and surge current resistance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a sheath filling state using a sole plate according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a circuit using repeated firing using a soleplate of the present invention and a voltage nonlinear coefficient of a voltage nonlinear resistor.

FIG. 3 is a diagram showing the relationship between the circuit used repeatedly and the surge current resistance of the voltage non-linear resistor.

FIG. 4 is a cross-sectional view showing a state in which sheathing is performed using a conventional sole plate.

[Explanation of symbols]

1 sheath 2 formed body 3 of MgAl ₂ O ₄ spinel decking 4 molded body having the same composition as a main component a soleplate

Claims (3)

[Claims] A voltage non-linear resistor element containing ZnO as a main component and various metal oxides as a sub component is made of Mg
A method for manufacturing a voltage non-linear resistor, which comprises firing on a sole plate mainly composed of Al ₂ O ₄ spinel. 2. The method according to claim 1, wherein the base plate has an apparent porosity of 10% to 30%. 3. A method for manufacturing a voltage non-linear resistor according to claim 1, wherein the base plate is made of a material in which SiO ₂ contained as an impurity is controlled to 0.5% or less.