JPS5994403A - Method of producing voltage nonlinear resistor - 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 directed to the manufacture of a voltage non-linear resistor in which electrodes are attached to both sides of a sintered body made by adding Gans frit to a zinc oxide varistor composition and firing it at a high temperature. It is about the method.

Conventional structure and its problems Traditionally, voltage nonlinear resistors were mainly made of silicon carbide.
So-called SiC varistors, which are hardened with a porcelain binder, have been widely used.
A so-called zinc oxide varistor, which uses a sintered body to which metal oxides such as , Bi2O3, and CO2o3 are added, mixed, molded, and fired, has been produced and put into practical use.

The voltage-current characteristics of this type of voltage nonlinear resistor (hereinafter referred to as a varistor) are generally expressed by the following equation.

I = (v/C)" However, engineering is the current, ■ is the voltage, and C and a are constants.The characteristics of a varistor can be expressed by two constants, C and a.C is the current of 1 ampere. Generally, it corresponds to the resistance value of a fixed resistor, and for a varistor, it is desirable that the voltage non-linearity index α is as large as possible.

The inventors replaced C with a current of 1 opA, 1oo μA
, 1mA, -.

Voltage at 100A■1oμA・100μA”1mA
+..."vlooA is used.

The a of zinc oxide varistor is extremely large, ranging from 40 to 100.
It has remarkable effects on voltage stabilization and stage voltage suppression, and is widely used to protect electronic equipment. Recently, there has been an active movement to use zinc oxide varistors in high voltage, high energy fields such as lightning arresters.

However, the zinc oxide varistor used in lightning arresters and the like is constantly applied with high voltage and must absorb high energy such as lightning surges, so the shape of the zinc oxide varistor element becomes large. Zinc oxide varistor elements used to protect electronic devices usually have a diameter of 3 to 14 mm and a thickness of 0.5 to 2 m, whereas zinc oxide varistor elements used in lightning arresters etc. have a diameter of 30 mm. Shuto~80mm
, and the thickness is 3 to 60 ran.

Since the zinc oxide varistors used in lightning arresters and the like are large in size, the required performance cannot be met using normal manufacturing methods for small devices.

Among the required performances, the charging life characteristics, pulse life characteristics, and discharge withstand characteristics are particularly important. As a measure to improve the energized life characteristics of conventional small zinc oxide varistor elements, (1) After applying glass to a sintered body, heat treatment is performed at 500°C to 850°C to diffuse the glass. (2) Anhydrous borosilicate Acid (B203)
A vitreous additive such as barium oxide (EaO) is added to the mixture and fired. (3) Bismuth borosilicate glass or lead borosilicate glass is added and fired. (4) A method has been adopted in which a glass made of bismuth oxide, boric anhydride, cobalt oxide, or silver oxide is added and fired. However, when the above method is applied to a large-sized element, the glass cannot be completely diffused into the element because the element is thick in method (1), and stable performance cannot be obtained. In method (2), gelation of the slurry of the raw material mixture occurs, so a calcination step is required as a countermeasure against this, and furthermore, the moldability is poor and cranks occur inside the element.

Furthermore, the discharge withstand capacity and pulse life deteriorate. Method (3) has no problems with the manufacturing process, but the lifespan of charging is a little poor.
The discharge capacity and pulse life are also disappointing. Method (4) also has no problems in the manufacturing process, but it has problems such as insufficient energization life and weak discharge withstand and pulse life.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention seeks to provide a method for manufacturing a voltage nonlinear resistor that has excellent charge life characteristics, pulse life characteristics, and discharge withstand capacity even with large zinc oxide varistor elements. .

Structure of the Invention In order to achieve this object, as a method for manufacturing the voltage nonlinear resistor of the present invention, the constituent materials and amount of glass frit to be added to the zinc oxide varistor composition were studied, and especially high voltage,
Charge life characteristics and pulse life characteristics of zinc oxide varistor elements in the high energy field.

It has improved discharge resistance. Specifically, bismuth oxide (B12O3) 40 to 9wt%, silica (S
102) 5-2 s iv t%, boric anhydride (B
203) 10-30 wt %, e silveride (A
q2'O) 5-30 wt, magnesium oxide (
A glass composition consisting of 2 to 20 wt% of MgO)
0.01 to 6 parts by weight of glass frit, which has been melted and cooled at 0°C to 1250°C to 111°C, is added to ioo parts by weight of the zinc oxide varistor composition, mixed and molded, and the molded product is heated to 860'°C. The present invention provides a method for manufacturing a patented nonlinear resistor, which is characterized in that it is calcined at ~950°C and an electrode is provided on a sintered body that is oxidized on the side surface of the calcined body.

Description of examples Hereinafter, the present invention will be explained according to Examples.

First, bismuth oxide (B1203) 40-9wt%,
Silica (S 102) 5-25 wt%, boric anhydride (B
203) 10-30 wt%, silver oxide (A g 20
) 5-3 Q w t%, magnesium oxide (Mq
O) 2 to 20 wt% are mixed together, the mixture is placed in a platinum crucible, and after melting at 1000°C to 1250°C, it is poured into water, rapidly cooled, and pulverized in a bot mill to make a glass frit.

On the other hand, zinc oxide (Zn0) s 5-9 s, 5moz
%.

Oxidized beef soup (B i 203) 0.01-5
mot%, cobalt acid (CO2O3) αO? −
5mot%, manganese oxide (MnO2) o, o1
~5 rnot %, antimony oxide (b b 20
21) O-02~10 rrroi! , %pChromium oxide (Cr2o3) 0.01-5m0L%, Silica (bi,02) 0.02-10molf-%,
Nickel oxide (N i O) 0.02-10m0t%
, aluminum oxide (At203)'0.001~0.
0.05 moA% (hereinafter referred to as lista composition) is prepared, 0.01 to 6 parts by weight of the glass frit is added to 100 parts by weight of this varistor composition, mixed and molded, The molded body is calcined at 850°C to 950°C, and bismuth oxide (Bi203) is added to the side surface of the calcined body.
, silica (Sin2) antimony dodecide (Sb203)
Apply a side high resistance agent consisting of
Electrodes are attached to both sides of the cylindrical sintered body obtained by firing at ℃ by metal spraying.

A comparison of the characteristics of the inventive example and the conventional example made in this way is made using a sintered body with a diameter of 33mm and a thickness of 30mm, as shown in Figures 1 and 2.
As shown in Fig. 3. FIG. 1 shows the charging life characteristics, FIG. 2 shows the pulse life characteristics, and FIG. 3 shows the discharge endurance characteristics. In the energization life test, a sample is placed in a thermostatic oven at 130'C, and an AC voltage having a peak voltage corresponding to the voltage of 95 parts of vlmA of the sample is applied between the electrodes of the sample, and the increase in leakage current is determined. I looked into it.

Pulse life characteristics are determined by repeatedly applying pulses with a current waveform of 8 x 20 μs and a current peak value of 5000 A to the sample.
The rate of change in mA was investigated〇 On the other hand, the discharge withstand characteristics of the sample when a pulse current with a current waveform of 4 x 10 μs was applied twice
In Figure 0, which examines the rate of change at 1 mA, A is the characteristic of the product of the present invention, and Figure 2 is the characteristic of the conventional product.

The above results show that the product of the present invention is bismuth oxide (131203).
50 wt%, silica (Sin2) 10 wt%
, boric anhydride (B203) 20 wt%, silver oxide C
Aq20) 20wt, magnesium oxide (1v1
Go) 10 wt% was melted at 1200°C, then rapidly cooled, and the finely ground glass frit was made into a varistor composition (Z
n O95,495mo -1% + old 00.5mot
%, C02o30.5m0L%.

3 Mn O20,6rno A%, 5b2031. omo
l-% zCr2030.6mo1%, 5in20.6
m0L%, Ni01, Omo1%, At2030. O0
0.1 part by weight is added to 100 parts by weight (5mo1%), mixed and molded, the molded body is calcined at 900°C, and the side surface of the calcined body is made of bismuth oxide, silica, and antimony oxide. It was coated with a high resistance agent and fired at 1000°C. In addition, the conventional product is b 1203b a, 4
wt%.

S 10 12.5 vv t%, B2O312
,5vvt%,Co08.3wt%pAg
The glass composition was 2OB, 3Wt, and other conditions were the same as those of the present invention.

If the amount of glass frit added is less than 0.01 part by weight, the effect of improving the charging life characteristics is lost, while if it exceeds 5 parts by weight, the discharge withstand capacity deteriorates. Further, if B120s in the glass frit is less than 40 wt%, vitrification becomes difficult, and if it exceeds 90 wt%, the voltage nonlinearity index a of the device becomes poor. Next, if the content of 5102 is less than 5 wt %, the life of the element when charged with electricity will be poor, and if it exceeds 25 wt %, the discharge withstand capacity will be poor. Further, when B2O3 is less than 10 wt%, the voltage nonlinearity index α becomes poor, and when it exceeds 30 wt%, the discharge withstand capacity becomes poor. And Ag2O is 5wt
If it is less than 3% by weight, the charging life characteristics will be poor, and if it exceeds 3°wt%, the discharge withstand capacity will be poor. Also, MqO is 2w
If it is less than t %, the pulse life characteristics will deteriorate, and if it is less than 20 w
When the amount exceeds t%, it is believed that vitrification is difficult.

Effects of the Invention As described above, the present invention can greatly improve the charge life characteristics, pulse life characteristics, and discharge withstand characteristics of a large-sized zinc oxide varistor element, and has great practical effects.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a comparison between the present invention product and a conventional product in terms of energization life characteristics, Figure 2 is a diagram showing a comparison between the present invention product and a conventional product in terms of pulse-on life characteristics, and Figure 3 is a diagram showing the discharge withstand capacity. FIG. 2 is a diagram showing a comparison between a conventional product and a conventional product with undeveloped characteristics. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure Ichimochiran (hr&) Figure 2 - 69110 times (@) Figure 3

Claims (2)

[Claims] (1) Bismuth oxide (Bi203) 40-90wtL%
. Silica (S i 02 ) 6-26 w't%, boric anhydride (B203) 10-30 wt%, silver oxide (
A920) 5-30 wt%, magnesium oxide (d
qo) 100% of the glass composition consisting of 2 to 20 wt%
After melting at 0°C to 1260°C, cooling and finely pulverizing Gansu frit is added in an amount of 0.01 to 5 parts by weight based on the weight part of the zinc oxide varistor composition i'oo, mixed and molded. Calcining at a temperature of 100°C to 950°C, applying a paste of a mixture of bismuth oxide, silica, and antimony oxide to the side surface of the calcined body, and providing an electrode on the sintered body obtained by firing at a temperature of 1000°C to 1400°C. A method for manufacturing a voltage nonlinear resistor characterized by: (2) Change the blending composition of the zinc oxide varistor composition to zinc oxide (
ZnQ) 85-98.5 mot%, bismuth oxide (B
i 2'0. , ) 0.01-5 moA%, cobalt oxide (Co203) o, o1-5rnot%, manganese oxide (MnO2) 0.01-5 mot%, antimony oxide (Sb203) 0.02-10 mot%,
Chromium oxide (Cr203) o, o1~5rnot%,
Silica (S z 02 0.02~.10 mot%
, nickel oxide (j?1o) 0.02~10m0t%
, aluminum oxide (At2o3) 0.001-0.0
A method for manufacturing a voltage nonlinear resistor according to claim 1, in which the voltage is reduced by 5 moj%.