JPH0869902A - Manufacture of thermistor ceramic - Google Patents

Abstract

PURPOSE: To provide thermistor ceramic which is composed of a manganese- nickel-copper oxide and shows a small rate of resistance change under a high- temperature, high-humidity condition and the element assembly of which has a high mechanical strength. CONSTITUTION: The thermistor ceramic is manufactured in such a way that at least aluminum oxide or zirconium oxide is added to a manganese-nickel- copper oxide at a rate of 0.1-20.0wt.% at the time of grinding the oxide after calcination and the mixed powder is molded and burnt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a temperature sensor, a power thermistor, or a thermistor porcelain used for temperature compensation of a circuit.

[0002]

2. Description of the Related Art Conventionally, a thermistor porcelain has been formed by adding aluminum or the like to a manganese-nickel-copper oxide.

[0003]

The thermistor porcelain having the above-described structure has an effect that the resistance change rate is small when used under high temperature and high humidity. However, it cannot be said that the element body has high mechanical strength.

Therefore, an object of the present invention is to provide a thermistor porcelain having a small resistance change rate and a high mechanical strength of an element body when used under high temperature and high humidity.

[0005]

In order to achieve this object, the present invention provides a method of calcining a manganese-nickel-copper oxide and then crushing it so that at least one of aluminum oxide and zirconium oxide is 0.1% or less. ˜20.0% by weight is added and molded, and then fired.

[0006]

According to this method, aluminum oxide or zirconium oxide does not form a solid solution with the manganese-nickel-copper oxide, but exists in a dispersed state at the grain boundary. As a result, perhaps by increasing the bonding strength of the manganese-nickel-copper oxide particles, the mechanical strength of the element body is increased, the influence of the outside air is prevented at high temperatures, and the moisture penetrates into the particles at high humidity. Can be prevented and the rate of resistance change can be reduced.

[0007]

EXAMPLE An example of the present invention will be described below.

[0008] Manganese, nickel and copper metal oxides were mixed in a predetermined amount so that the composition ratio other than oxygen was the composition shown in (Table 1), wet-mixed for 16 hours in a ball mill, dried and then 800 It was calcined at ℃ for 2 hours.

[0009]

[Table 1]

Next, the metal oxides (Al ₂
O _3, ZrO ₂₎ was added, subjected to 18 hours milling in a ball mill, dried, added 10% by weight relative to pulverized powder with an aqueous solution of 10 wt% of PVA (polyvinyl alcohol), subjected to granulation It was

After that, pressure molding was performed into a disk shape having a diameter of 10 mm and a thickness of 1 mm, followed by firing at 1100 ° C. for 2 hours to obtain a sintered body. The electrode paste was applied to both surfaces of the sintered body and baked to obtain a disk type sample. Created.

The high temperature of each completed sample (Table 1) (150
The results of the resistance change rate and the bending strength test of the element after being left for 1000 hours in (° C.) and in humidity (40 ° C. 90% Rh) are shown.

For comparison, the results of the samples containing no aluminum oxide or zirconium oxide are also marked with *.

As shown in (Table 1), the resistance change rate of all the samples to which no metal oxide was added after being left in high temperature and humidity for 1000 hours was 5% or more, whereas the metal oxide was added. The samples that have been processed are improved to 5% or less. Further, the mechanical strength of the element body is 2 kgf or less for all the samples to which the metal oxide is not added, whereas the mechanical strength of the sample to which the metal oxide is added is improved to 2 kgf or more.

As described above, after calcination of the manganese-nickel-copper oxide, at the time of pulverization, at least one of aluminum oxide and zirconium oxide is added to 0.1-20.
By adding 0% by weight, it is possible to provide a thermistor porcelain having a small resistance change rate under high temperature and high humidity use and a high element mechanical strength.

Although this is not clear at this point,
Aluminum oxide or zirconium oxide does not form a solid solution with the manganese-nickel-copper oxide and exists at the grain boundary, and enhances the binding force of the manganese-nickel-copper system particles having a weak binding force and surrounds the periphery of the particles. This is to prevent the influence of outside air and the infiltration of water.

Next, the reason for limiting the numerical values will be described.
If the added metal oxide is less than 0.1% by weight, the resistance change rate under high temperature and high humidity use is small, and there is no effect of obtaining a thermistor porcelain having high mechanical strength of the element body, while it exceeds 20.0% by weight. Since the resistance of the oxide, which is the main component, suddenly increases, and the variation in the electrical characteristics also rapidly increases, it is not practical and was outside the range of the present invention.

In the above examples, the case where one kind of each of aluminum oxide and zirconium oxide was used as the metal oxide was explained, but two kinds of aluminum oxide and zirconium oxide were added to the main component. In this case, the same effect can be obtained. As for the shape, the case of using the disk type has been described this time, but the same effect can be obtained regardless of the shape.

[0019]

Industrial Applicability As described above, according to the present invention, at least one of aluminum oxide and zirconium oxide is 0.1% or more at the time of pulverization after calcination of the manganese-nickel-copper oxide.
By adding ~ 20.0% by weight, after sintering, aluminum oxide and zirconium oxide are dispersed and present in the element body, so that the resistance change rate under high temperature and high humidity use is small and the element body mechanical strength is low. It is possible to realize high thermistor porcelain and has great industrial value.

Claims (1)

[Claims] 1. A manganese-nickel-copper oxide is calcined, and when pulverized, at least one of aluminum oxide and zirconium oxide is added in an amount of 0.1 to 20.0% by weight, and then molded and fired. Manufacturing method of thermistor porcelain.