JPH07211518A - Production of voltage non-linear resistor - Google Patents

Abstract

PURPOSE:To obtain a voltage non-linear resistor which has an excellent voltage non-linearlity and suppressed variance by containing a zinc oxide as an essential composition and at least Bi, Co, Mn, and Ti as a subcomposition and adding a specific amount of Sn dissolving in a solution. CONSTITUTION:This method is used to produce a voltage non-linear resistor by using a zinc oxide as an essential composition, containing as a subcomposition at least Bi, Co, Mn, and Ti in terms of Bi2O3, Co2O3, MnO2, and TiO2 respectively, that is, 0.100-2.000mol% Bi2O3, 0.100-2.000mol% Co2O3, 0.100-2.000mol% MnO2, 0.000-2.000mol% TiO2, and adding 0.001-0.100mol% Sn dissolving in a solution. In this method, as a dissolved Sn in a solution, one or two kinds or more of tin chloride are dissolved in a pure water to make a solution. Thus, tin is uniformly dispersed, suppressing the variance of voltage non-linearlity.

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 voltage non-linear resistor containing zinc oxide as a main component.

[0002]

2. Description of the Related Art Voltage non-linear resistors having zinc oxide as a main component are widely used because they have excellent voltage non-linearity, large surge current withstand capability.

The manufacturing method is such that zinc oxide as a main component is mixed with bismuth, cobalt, manganese, titanium and the like as auxiliary components, and the mixture is granulated, molded and fired.

A varistor voltage can be arbitrarily obtained by the subcomponents, and in general, titanium is often used for a low voltage of 50 V or less. However, when titanium is used, there is a problem that the voltage non-linearity deteriorates. On the other hand, tin is known as an additive for improving the voltage nonlinearity.

[0005]

However, in the case where tin is contained in order to improve the voltage non-linearity, if the content of tin is large, it reacts with bismuth in the firing process to form tin and a bismuth compound, resulting in abnormal grains. Growth is likely to occur, which causes variations in varistor voltage.
In addition, when the content is small, there is a problem that the dispersion of varistor voltage becomes small, but the dispersion of tin becomes non-uniform, the dispersion of voltage nonlinearity becomes large, and the effect of improving voltage nonlinearity is small. Was.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a voltage non-linear resistor having excellent voltage non-linearity and small variations.

[0007]

In order to achieve this object, a method of manufacturing a voltage non-linear resistor according to the present invention comprises zinc oxide as a main component and at least bismuth, cobalt, manganese and titanium as auxiliary components. Then, 0.001 to 0.100 mol% of tin in solution is added.

[0008]

As a result, tin is uniformly dispersed because it is added in the form of a solution, the variation in voltage nonlinearity is reduced, and the addition amount can be reduced, so that the variation in varistor voltage is also reduced. is there.

[0009]

EXAMPLES Examples of the present invention will be described in detail below.

The main components of zinc oxide (ZnO), bismuth oxide (Bi ₂ O ₃ ), cobalt oxide (Co ₂ O ₃ ), manganese oxide (MnO ₂ ) and titanium oxide (TiO ₂ ) are shown in Table 1. The composition ratio was weighed. On the other hand, tin nitrate was dissolved in pure water to prepare a tin solution. A tin solution was added to the weighed raw materials in the composition ratio shown in (Table 1). In this raw material,
Pure water was added to a solid content ratio of 60% by weight, PVA (polyvinyl alcohol) as an organic binder was added in a solid content ratio of 0.5% by weight, and the whole amount was put in a ball mill together with zirconia boulders and mixed for 24 hours to form a slurry. Obtained.
This slurry was granulated with a spray dryer.

This granulated powder was pressure-molded into a disk having a diameter of 2 mm and a thickness of 2 mm to obtain a molded body. This molded body was put into an alumina porcelain pod and fired in the atmosphere at 1300 ° C. for 3 hours to obtain a sintered body. A silver paste was screen-printed on both end faces of this sintered body and baked at 600 ° C. to provide a silver electrode. After attaching a lead wire to this electrode portion by soldering, the exterior was coated with a thermosetting resin. In addition, as a conventional example, tin oxide (SnO ₂ ) was used in the same manner.

For each of the samples prepared by the above procedure, 20 varistor voltages (V1 mA / mm) each
And calculate the voltage non-linearity coefficient (α).

[0013]

[Outer 1]

Is shown. The varistor voltage indicates a voltage value per 1 mm of element thickness when a current of 1 mA is applied. The voltage non-linearity coefficient was calculated by the following formula from the voltage value when each current of 1 mA and 100 μA was passed.

Α = (logI ₁ −logI ₂ ) / (logV ₁ −logV ₂ ) However, I ₁ , I ₂ ; measured currents V ₁ , V ₂ ; voltage values at I ₁ , I ₂ Bismuth from sample number 1 When it is 0 mol%, the varistor voltage is very high and the voltage nonlinearity is lowered. Sample number 5
If it exceeds 2 mol%, the voltage non-linearity decreases. Cobalt and manganese are 0 from sample numbers 6, 9, 10, and 13
The voltage non-linearity deteriorates even when the content is mol% or conversely exceeds 2 mol%. When titanium exceeds 2 mol% as compared with Sample No. 17, the varistor voltage becomes high and the voltage nonlinearity also deteriorates. When the tin solution is less than 0.001 mol% than the sample Nos. 18 and 19, the voltage non-linearity is lowered, and when the tin solution exceeds 0.2 mol% from the sample No. 22, the varistor voltage varies greatly. On the other hand, in the case where tin is added as the conventional powder from sample numbers 23 to 26, the variation in the voltage nonlinear coefficient becomes large when the addition amount is small.

[0016]

[Table 1]

Further, as shown in FIGS. 1 and 2, when tin is added as a solution, the voltage nonlinearity is improved even with a small amount, and the variation (σ) of the voltage nonlinear coefficient is small.

Although tin nitrate was dissolved in pure water to prepare a tin solution in this embodiment, the same effect can be obtained by using various tin compounds such as tin chloride and tin sulfate.

The effect of the present invention remains unchanged even if additives such as Cr, Ni, Sb, Al and B are added to further improve various characteristics.

[0020]

As described above, according to the present invention, the main component is zinc oxide, and at least bismuth, cobalt, manganese, and titanium are contained as secondary components, and 0.001 to 0.100 of tin is dissolved. By adding mol%, tin is uniformly dispersed, and it is possible to easily provide a voltage nonlinear resistor having excellent voltage nonlinearity and small variations.

[Brief description of drawings]

FIG. 1 is a diagram showing a voltage non-linearity coefficient (α) of the present invention and a conventional example.

FIG. 2 is a diagram showing variations in the voltage nonlinear coefficient (α).

Claims (2)

[Claims] 1. Zinc oxide as a main component, and at least bismuth, cobalt, manganese, and titanium as auxiliary components are converted into Bi ₂ O ₃ , Co ₂ O ₃ , MnO ₂ , and TiO ₂ , respectively, to obtain Bi ₂ O ₃ : 0.100 to 2.000 mol% Co ₂ O _3: 0.100 to 2.000 mol% MnO _2: 0.100 to 2.000 mol% TiO _2: .000-2.000 is contained mol% , 0.001 to 0.1 of solution tin
A method for manufacturing a voltage non-linear resistor added with 00 mol%. 2. The production of the voltage non-linear resistor according to claim 1, wherein one or more of tin nitrate, tin sulfate and tin chloride is dissolved in pure water to form a solution as tin in solution. Method.