JPH03214705A - Manufacturing method of voltage nonlinear resistor element - Google Patents

Abstract

PURPOSE:To prepare a lightening arrester element having a high discharge withstand current rating by forming an SiO2 thin film or an Si3N4 thin film, which are high resistance films, on the side of a zinc oxide varistor base body by a chemical or physical filming method. CONSTITUTION:0.3mol% to 1.5mol% respectively to the total amount of the oxides of bismouth, cobalt, manganese, antimony and chrome are added to zinc oxide powder for being fully crushed and mixed followed by granulation to manufacture raw material powder. This raw material powder is compression formed to the size having a diameter 40mm and the thickness 30mm, a binder is fully decomposed in the atmosphere at a temperature of 700 to 900 deg.C for being sintered in the atmosphere at 1200 deg.C to obtain a zinc oxide varistor base body 1. A high resistance film 2 of SiO2 is formed on its side by using a plasma CVD method. Thereby, an element excellent in a dischargeproof amount characteristic can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a voltage non-linear resistor which has zinc oxide as a main component and has a high resistance layer formed on the side surface of a sintered body which itself exhibits voltage non-linearity. The present invention relates to a method for manufacturing an element.

Conventional technology Conventionally, resistors with high voltage non-linearity have been made by using zinc oxide as a main component, adding oxides such as bismuth and manganese as additives, molding and firing.
Zinc oxide called Halista? Widely used as pressure stabilizing elements, surge absorbing elements, lightning arresters, etc.

When this zinc oxide varistor is used as a power surge arrester, one of the required characteristics is discharge withstand capability. As specified in JRC-187-1973, a 4/10 μs impact current is applied twice at 5 minute intervals.
This is the maximum value of peak current that the element can withstand.

Traditionally, as a manufacturing method for power surge arresters, SiOz was added to the side of the lightning arrester element in order to increase the discharge capacity.
A mixture such as Znt sb2 012.8I2 03 is applied and sintered to form a high-resistance layer (Japanese Patent Laid-Open No. 1986-
69804), sb. ():+
A mixture consisting of BizC) + SiQ■ etc. is placed,
A method has been known in which a high resistance layer is formed on the side surface of a lightning arrester element by a gas-solid phase reaction (Japanese Patent Publication No. 15128/1983).

Problems to be Solved by the Invention However, in the above method, in the former case, does the size of the particles in the high-resistance film after sintering become non-uniform? In some cases, the formed film may be a bolus, and the adhesion between the lightning arrester element and the high-resistance film may not necessarily be sufficient. Furthermore, in the latter case, the uniformity of the produced film thickness may not be good. If the adhesion between the high-resistance layer and the lightning arrester is not sufficient, surge current will leak between the lightning arrester and the high-resistance layer, and the characteristics of the high-resistance layer that should have been achieved will not be fully met, resulting in discharge. The limit value of tolerance may decrease.

Furthermore, if the thickness of the high-resistance film is not uniform, a surge current will flow selectively through the thinner parts of the film, causing a reduction in the limit value of the discharge withstand capacity.

The present invention is intended to solve these problems, and aims to manufacture a lightning arrester with high discharge resistance by uniformly forming a high-resistance film with high adhesion to a lightning arrester element.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for manufacturing a voltage non-linear resistor element of the present invention provides a method of manufacturing a voltage non-linear resistor element by applying a high-resistance film such as an SiO2 thin film or Si3NaF
This paper proposes a method of forming an il film using a chemical or physical film forming method.

Function Generally, when a thin film is formed using a chemical or physical film forming method, it is possible to form a dense and highly adhesive thin film. In addition, s10zFiN film or S! The 3N4 thin film has excellent thermal shock resistance and insulation properties, and is a material that can sufficiently withstand element heat generation due to surge currents and strong electric fields when surge currents are applied. From this, the method described above makes it possible to create a lightning arrester element with higher discharge resistance.

EXAMPLES Hereinafter, the manufacturing method of the present invention will be explained in detail based on examples.

First, oxides such as bismuth, cohardt, manganese, antimony, and chromium are added to zinc oxide powder in an amount of 0.3 mo1% to 1.5 mo1% based on the total amount, and the mixture is sufficiently crushed and mixed, and then granulated. , raw material powder was prepared. This raw material powder is compressed into a size of 40 mm in diameter and 30 mm thick, and after sufficiently decomposing the binder in the air at a temperature of 700°C to 900°C, it is placed in the air. It was sintered at 200°C to obtain a zinc oxide varistor element.

A high-resistance film of SiO2 was formed on the side surface of the varistor body thus obtained using plasma CVD. A specific manufacturing method is shown below.

That is, as shown in FIG. 2, the upper and lower parts of the varistor element 4 are sandwiched between rotatable jigs 5, and after the varistor element 4 is heated in advance to a temperature of 300°C using infrared rays, the varistor element 4 is slowly rotated. The mixture was allowed to pass through the reaction chamber 6 at the same time. Here, the film thickness was controlled by the time for passing through the reaction chamber 6. The internal capacity of the reaction chamber 6 is approximately 65 liters, and the reaction gas is SIH4
Gas is 30 (ml/min), N20 gas is 800 (ml/min)
A gas introduction valve 8 into the reaction chamber 6 at a flow rate of ml/min)
is introduced in a controlled manner, and the gas pressure in the reaction chamber 6 during film formation is I
Torr, was controlled by a main valve 9 to a vacuum pump (not shown). Further, the discharge electrode 7 for generating plasma was a 40 cm square plane, and a 13.56 MHz high frequency power source was used to supply a power of 500 (W). The film forming speed on the varistor body 4 under the above conditions is approximately 150
(ml/min). By changing the film thickness under these conditions,
Four types of samples? accomplished. Both end faces of the sample thus prepared were polished to form aluminum capacitive electrodes.
A harista element was fabricated. A schematic diagram of the varistor element produced in this manner is shown in FIG. Table 1 below shows the thickness of the sample SiO₂VR film prepared.

In addition, in FIG. 1, 1 is a zinc oxide varistor element body, 2
is a SiO2 thin film, and 3 is an electrode.

<Table 1> For comparison, SO is used as a conventional element. Instead of a thin film, S ioz , Z
n7 Sbg 012. A sample (Sample 5) was prepared by coating a thin layer of an insulating material containing B iz 03 in an appropriate proportion, heat-treating the sample, and forming an electrode in the same manner as described above.

An impact current of 4/10 μs was applied twice at an interval of 5 minutes to the thus obtained harista elements (samples 1 to 5), and the limit value of the peak current that the element could withstand was measured.

The results are shown in Table 2 below. In Table 2, × The mark is the current value at which the element was destroyed.

Table 2〉? From Table 2, it can be seen that the discharge withstand capacity of the device in which the s+ozfl film is coated on the side surface of the varistor body is significantly superior to that of the device without any coating or the device coated with an insulating material through heat treatment. In addition, in this experiment, the discharge withstand capacity increased as the thickness of the SiO thin film became thicker;
Even in μm devices, is it recognized that the characteristics are sufficiently improved compared to conventional examples? It will be done.

In this experiment, the SiO2 thin film was SiH. Although the plasma CVD method using N20 gas and N20 gas is used, this method is not limited to the plasma CVD method. It is also possible to produce a SiO2 thin film by the vapor deposition method, and it is possible to apply this method to the device of the present invention.

Here, the above SiOzFi! Even when a high resistance film was formed using a S13N4 thin film instead of the film, the same effect as in the above example could be obtained. Table 3 below shows the thickness of the Sf3N4 thin film of the prepared sample. Here, the sample preparation conditions are such that the reaction gas is S i H 4 gas: 30 (ml
/min), Nz gas: 800 (ml/min), and film forming rate on the varistor body: approximately 50 (nm/min).
The conditions were all the same as in the above example, except that the conditions were set to (min).

Below is Table 3 with blank spaces> Here, sample 6 is the same as sample 1 of the above example. For these samples, the same impact current as in the above example was applied, and the limit value of the peak current that the device could withstand was measured. The results are shown in Table 4 below. Also, in Table 4, the measurement results of the above-mentioned comparative sample 5 are listed for reference.

Table 4〉? As shown in Table 4 below, excellent discharge withstand characteristics can be obtained even when a SisN4 thin film is used. In particular, in the case of Si3N4ffi film, the film thickness is 2.0μ
Even in the element of m, the characteristics are sufficiently improved compared to the conventional example. Moreover, this St3Na thin film is
SiH3 gas and NH. It can also be produced by a plasma CVD method using a gas, and in addition, as in the above embodiment, other chemical vapor deposition methods such as a low pressure CVD method or an atmospheric pressure CVD method, or a physical vapor deposition method such as sputtering can be used. Of course, it can also be produced by

Effects of the Invention As described above, according to the present invention, S is grown on the side surface of a zinc oxide halistan element body using a chemical or physical thin film growth method.
By forming the iO2 thin film or the S i 3Na 71 film, a voltage nonlinear element with excellent discharge withstand characteristics can be manufactured.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a voltage nonlinear resistor element manufactured by the manufacturing method of the present invention, and FIG. 2 is a diagram showing an example of a thin film forming method in the manufacturing method of the present invention. l... Zinc oxide varistor element, 2 Old... Si
n2 thin film, 3... Electrode, 4... Zinc oxide varistor element, 5... Rotatable jig, 6...
Old...Reaction chamber, 7...Discharge electrode, 8...
・Gas introduction valve, 9...Main valve to the vacuum pump.

Claims (1)

[Claims] Voltage non-linearity characterized by forming a SiO_2 thin film or Si_3N_4 thin film on the side surface of a zinc oxide varistor element body which contains zinc oxide as a main component and exhibits voltage non-linearity using a chemical or physical thin film growth method. A method for manufacturing a resistor element.