JPH0315321B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a glass-filled nonlinear resistor.

The small glass-encapsulated component has a structure as shown in FIG. 1, which is represented by a diode. That is, the element 1 is held between a pair of slug leads 2 whose heads are made of a dimet wire in a glass tube 3, and the glass tube 3 is melted by heating, and the glass and the dimet portion are fused. Fixed and sealed. Parts with such a configuration have been put into practical use in other parts such as thermistors because of their easy-to-use shape and high reliability as their characteristics are not easily affected by environmental conditions.

By the way, this component is usually made by placing a glass tube, an element, and a slag lead in a jig made of graphite, and then raising the temperature in a vacuum or nitrogen atmosphere. The temperature is raised by passing an electric current through a tunnel type furnace or a graphite jig, and utilizing the Joule heat generated by the resistance. The reason why the treatment is performed in a vacuum or nitrogen atmosphere is to prevent wear and tear of graphite due to oxidation, maintain cuprous oxide on the surface of the dimet portion, and prevent oxidation of the slag lead. Furthermore, graphite is used because it is stable even at high temperatures, does not fuse with molten glass, and has excellent workability.

If a nonlinear resistor containing zinc oxide as a main component is manufactured under the manufacturing conditions of these parts, its nonlinearity will be significantly degraded during the sealing process, and the original function will not be obtained. Although the reason for this is not clear, it is thought that the characteristics change due to the release of oxygen adsorbed in the element.

As a result of experiments, the present invention has led to the creation of a ZnO-based nonlinear resistor that has excellent characteristics under oxygen partial pressures within a suitable range, and which is comparable to other glass-encapsulated components. This is a practical non-linear resistor using almost the same manufacturing method.

Hereinafter, the manufacturing method of the present invention will be explained based on Examples.

Zinc oxide (ZnO) is mixed with several additives such as bismuth oxide and cobalt oxide, and the resulting powder is formed into a size of 40mmφ x 20mmt.
It was fired at 1250℃. After slicing the thus produced block into 0.3 mm thick pieces, silver electrodes were coated and baked on both main surfaces. The thin plate element thus obtained was cut into 1.0 mm x 1.0 mm pieces using a dicing machine. The thus obtained element was held in a lead glass tube by a pair of slug leads whose heads were made of dimeth wire, and set in a graphite jig.
This was placed in a tank and the pressure was reduced to adjust it to each oxygen partial pressure, then electricity was applied to a graphite jig to heat it at 660° C. for 1 minute, and then it was allowed to cool. As a result, the glass tube is melted, and the glass and the dimet portion are fused and sealed. Here, the results for each oxygen partial pressure are as shown in Figure 2, and the oxygen partial pressure is 0.5 Torr.
If it is less than 10, the nonlinear index α of the element is less than 10, and the original characteristics of a zinc oxide-based varistor cannot be obtained. Since the amount of oxygen in this region is small, the effect cannot be obtained. Then, when the oxygen partial pressure is increased beyond 0.5 Torr, the nonlinear index α improves,
Characteristics before device encapsulation were obtained. However, when the oxygen partial pressure exceeded 30 Torr, the slag lead was severely oxidized, and the surface of the dimet portion became dominated by copper oxide, resulting in defects in the sealing quality. Furthermore, it was observed that the wear and tear of graphite progressed rapidly.

From the above, the atmosphere during temperature rise and sealing is oxygen partial pressure.
Normal characteristics can be obtained at 0.5 to 30 Torr, and this is a range that can be used as a commercial product. This makes it possible to put a glass-sealed zinc oxide nonlinear resistor into practical use, and the industrial efficiency of the present invention is great.

[Brief explanation of drawings]

FIG. 1 is a front view showing a cross section of a part of a general glass-sealed component, and FIG. 2 is a diagram showing the relationship between oxygen partial pressure and nonlinear index α for explaining the present invention. . 1...Element, 2...Slag lead, 3...Glass tube.

Claims (1)

[Claims] 1 A sintered nonlinear resistance element whose main component is ZnO is held between a pair of slug leads whose heads are made of dimeth wire in a glass tube, and the oxygen partial pressure is 0.5 to 30 Torr.
The glass tube is melted by increasing the temperature in an atmosphere of
A method for manufacturing a glass-filled nonlinear resistor, which is characterized by fusing and sealing glass and dimet wire.