JPS59169103A - Method of producing metal oxide 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 [Technical Field of the Invention] The present invention relates to a method for manufacturing a metal oxide nonlinear resistor, particularly a metal oxide nonlinear resistor used in an overvoltage protection device in an electrical system.

[Technical background of the invention and its problems]

Overvoltage protection devices are used in electrical systems to protect the electrical system by removing overvoltages superimposed on normal voltages.

This overvoltage protection device uses a non-linear resistor that exhibits substantially insulating properties at normal voltage and exhibits a relatively low resistance value K1-1 when overvoltage is applied.

The non-linear resistor is made of silicon carbide (SiC) or zinc oxide (
It is made by mixing metal oxides with ZnO) and firing the molded material.

For example, Zn08Q molar ratio, magnesium oxide (Mg(,
')) 14 mol%, bismuth oxide (Bi□Os>, rg
Antimony oxide (Sb20.), cobalt oxide (CoO)
, manganese oxide (MnO), chromium oxide ("r203
) r Weigh and mix 0.05 to 3.5 mol of ferrolyzed iron (Fe203) for a total of 6 mol of each.

Press the mixture to form a 1200" to 130"
A disc-shaped non-linear resistor material with a diameter of 6 (1+V and a thickness of 20 mt) was made by firing at a temperature of 0°C for 6 hours, and electrodes were formed by metal spraying to form a non-linear resistor.

In the nonlinear resistor manufactured in this way, the rate of change in resistance of the nonlinear resistor is large when a large current pulse is applied, and therefore it is not suitable for overvoltage protection devices that receive normal pulses or voltage surge pulses for a long period of time. However, there was a need for a metal oxide nonlinear resistor with stable electrical properties over a long period of time.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned needs, and it is an object of the present invention to provide a method for manufacturing a metal oxide nonlinear resistor whose electrical characteristics are less likely to deteriorate even when overcurrent pulses are repeatedly applied over a long period of time.

[Summary of the invention]

In order to achieve this object, the present invention involves molding zinc oxide or a mixture of zinc oxide and magnesium oxide as products, firing the molded body, and coating the side surface of the fired body with polyphenylene sulfide resin. Its characteristics.

[Embodiments of the invention]

Next, embodiments of the present invention will be described with reference to the drawings.

For example, 80 mol of ZnO and 14 mol of Mg, for example.

Bi, C), 2 mol H, Sb, 0,1.5
Molch, Co01.1 mole.

Cr, 030.5 mol%, Mo0o, s mol%,
Weigh Fe2O,0,4(-) at a ratio of %.Next, weigh; put the prepared oxide in, for example, a hall mill Q, and make a hall mill for 24 hours with Yue ion water and a The mixed oxide and binder are substantially homogeneously mixed.

The oxide is then placed in a granulation device, such as a spool dryer, to form spherical agglomerates having a particle size of, for example, 100 to 300 microns.

This powdery mixture is pressed, for example j white diameter 75
mrt+, formed into a disc with a thickness of 25 mm and fired in an electric furnace. The firing temperature is, for example, 1250°C, and the IC is suitably between 6 and 11.

After firing, the disc-shaped fired product shrinks more than before firing, but has a substantially homogeneous composition and density.

Next, both sides of the disc-shaped fired product are lightly polished to expose the fired part. This exposed surface K is thermally sprayed with, for example, aluminum to form an electrode and a non-linear resistor.

Further, a polyphenylene monocarphaide resin is applied to the side surface of this fired body, and after drying, this mixture is baked at, for example, 370° C. to coat the side surface. Note that the order of the polyphenylene sulfide resin coating step and the electrode forming step may be reversed.

The electrical characteristics of the metal oxide nonlinear resistor thus obtained are shown in FIGS. 1 and 2.

Figure 1 shows the rate of change in the value of V+m* (ΔVtm* = (V+mA') when a current of 10KA is applied up to 100 times.
-V1m* x 100). In the figure, curve B indicates the value of a nonlinear resistor manufactured using the conventional manufacturing method.
represents the value of the nonlinear resistor of the present invention. As is clear from the figure, the electrical characteristics of the metal oxide nonlinear resistor produced by the manufacturing method of the present invention were significantly improved.

Figure 2 shows the passing rate when the applied shock wave current value was changed to 100K. Curve N is the pass rate of the metal oxide nonlinear resistor manufactured by the conventional manufacturing method, and curve B is the pass rate of the metal oxide nonlinear resistor manufactured by the manufacturing method of the present invention.

As is clear from the figure, when the applied current is small, the difference between both lines A and H is small, but when a large current pulse is applied, the acceptance rate of the conventional nonlinear resistor drops significantly.

In the above examples, the zinc oxide content, the metal oxide composition, and the pass rate are not limited to the above examples. In addition, the baking tolerance range of polyphenylene sulfide resin coating is 330°C to 450°
A range of C is appropriate. Outside this temperature range, the strength of the coating film is not equal to that of light, and the pass rate for the shock wave current value decreases.

It goes without saying that the process conditions are not limited to those of the above embodiments.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to provide a metal oxide nonlinear resistor whose electrical characteristics are less likely to deteriorate even when overcurrent pulses are repeatedly applied over a long period of time.

[Brief explanation of the drawing]

FIGS. 1 and 2 are curve diagrams illustrating the electrical characteristics of a metal oxide nonlinear resistor manufactured using the manufacturing process of the present invention.

Claims (1)

[Claims] 1. The method is characterized by molding zinc oxide or a mixture containing zinc oxide and magnesium oxide as main components, firing the molded product, and coating the side surface of the fired product with polyphenylene sulfide resin by baking. A method for manufacturing a metal oxide nonlinear resistor. 2. The method for manufacturing a metal oxide nonlinear resistor according to claim 1, wherein the baking coating is performed at a temperature in the range of 330° to 450°C.