JPH0582313A - Composition for thermistor - Google Patents

Abstract

PURPOSE:To provide a composition for a thermistor which has a small resistance change rate by the use at a high temperature, high humidity and high reliability and is made of manganese-nickel-copper series oxide. CONSTITUTION:0.01-10wt.% of zirconium oxide is added to oxide in which 15-55 mole % of manganese, 15-85 mole % of nickel and 0.01-30 mole % of copper by ratio of only metal elements in such a manner that the total sum becomes 100 mole %, thereby constituting a composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a thermistor, and its resistance value changes from that before being placed in a high temperature and high humidity atmosphere even after passing through a high temperature and high humidity atmosphere (hereinafter This relates to a composition for a thermistor having a small resistance change rate under high temperature and high humidity use.

[0002]

2. Description of the Related Art Conventionally, as a thermistor composition comprising an oxide semiconductor containing manganese oxide as a main component, one containing manganese, nickel and copper is known.

It has also been proposed to improve the high temperature DC voltage load characteristics by adding a small amount of zirconium oxide to the oxide containing manganese, nickel and copper (see, for example, Japanese Patent Laid-Open No. 58-6102). ).

[0004]

However, manganese-
In the thermistor composition comprising an oxide of three metal elements of nickel-copper, or a known thermistor composition obtained by adding a certain amount of zirconium oxide thereto, the rate of change in resistance under use at high temperature and high humidity is There is a big problem. Therefore, an object of the present invention is to provide a composition for a thermistor composed of manganese, nickel, and a copper-based oxide having a small rate of change in resistance under use at high temperature and high humidity.

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have made earnest studies, and as a result, the ratio of only metal elements is 15 to 55 mol% of manganese, 15 to 85 mol% of nickel, and 0. Zirconium oxide is added in an amount of 0.01 to 30 mol% and a total of 100 mol% to 0.01 to 10 mol%.
It has been found that the above-mentioned problems can be solved by adding wt%.

[0006]

By using the composition for a thermistor having the composition of the present invention, the rate of change in resistance under the use of high temperature and high humidity can be remarkably reduced as compared with the conventional one.

[0007]

EXAMPLES Examples of the present invention will be described. Commercially available manganese tetraoxide, nickel oxide, copper oxide, and zirconium oxide are weighed and mixed so that the composition after sintering will be the composition ratios shown in Tables 1 and 2 below, and wet-mixed in a ball mill for 16 hours. In addition, these commercially available raw materials are Fe, Si, Na, K, and C.
It contains a trace amount of a metal compound such as a.

After that, it is dehydrated and dried, and powdered using a mortar and pestle. Next, put this powder in an alumina bowl and
Preliminary calcination at 1200 ° C. for 2 hours. The calcined product is finely pulverized with a ball mill, dehydrated and dried, polyvinyl alcohol (PVA) is added as a binder, and granulated into granules with a mortar and pestle, and then pressed into a disc shape with a diameter of 16 mm and a thickness of 2.5 mm. Mold.

Next, heating at 600 ° C. for 2 hours in the atmosphere,
After removing the binder, 1000 ° C to 14 ° C in the atmosphere
A sample is obtained by performing a main firing at 00 ° C. for 2 hours. A silver paste is screen-printed on both sides of the obtained sample and baked at 800 ° C. to form an electrode.

Each completed sample was subjected to the DC 4-terminal method,
Resistance value of 25 ℃ (R25), resistance value of 85 ℃ (R85)
Was measured and the specific resistance (ρ
25) and the B constant (B25
/ 85) was calculated and the results shown in Tables 1 and 2 below were obtained.

Further, each sample was put in boiling pure water at 1000 ° C., and after boiling for 50 hours, the resistance value was measured, and the following mathematical formula 3 was used.
, The resistance change rate (ΔR
25) was calculated and the results shown in Tables 1 and 2 below were obtained.

[0012]

[Equation 1] However, ρ25: specific resistance at 25 ° C (Ω · cm) S: electrode area (cm ² ) t: thickness of sample (cm) R25: resistance value at 25 ° C (Ω)

[0013]

[Equation 2] However, B25 / 85: B constant (K) R25: Resistance value at 25 ° C (Ω) R85: Resistance value at 85 ° C (Ω)

[0014]

[Equation 3] Where ΔR25: resistance change rate (%) after boiling test R25 ′: resistance value after boiling test (Ω) R25: resistance value before boiling test (Ω)

[0015]

[Table 1]

[0016]

[Table 2]

In Tables 1 and 2, Sample Nos. 1, 2, 3, 4, 5, 13, 14, 17, 17 marked with X are shown.
8, 19, 22, 23, 24, 27, 28, 29, 3
3, 34 and 39 are composition ratios outside the range of the present invention, and all of them have ΔR25 of more than 5.0%, and are shown for comparison with the composition of the present invention.

As is clear from Tables 1 and 2, the composition of the present invention has ρ25 of 0.57 to 1.62 × 10 ⁵ Ω · cm and B2.
All of 5/85 of 641 to 9993K are in a practically sufficient range, and ΔR25 is very small and stable at 0.9% to 4.9%.

Next, the reason for limiting the numerical values will be described. When the ratio of manganese is less than 15 mol%, ΔR25 is 5
%, Which makes it unsuitable for use under high temperature and high humidity (see, for example, Sample Nos. 4 and 5 in Table 1).

On the other hand, when the ratio of manganese exceeds 55 mol%, ΔR25 also exceeds 5% (see Table 1 for example).
No. 1, No. 2). Next, when the proportion of nickel is less than 15 mol%, ΔR25 exceeds 5% (for example, see Sample No. 2 in Table 1).

When the proportion of nickel exceeds 85 mol%,
It became difficult to sinter, and it was difficult to obtain a stable thermistor fired body. When the proportion of copper is less than 0.01 mol%, ΔR25 exceeds 5.0% (Sample No.
(See comparisons 30, 40). When the proportion of copper exceeds 30 mol%, ΔR25 exceeds 5% (for example, see Sample Nos. 3 and 4 in Table 1).

When the ratio of zirconium oxide as an additive is less than 0.01% by weight based on the main component, ΔR25 is 5%.
(For example, samples Nos. 13, 14, 18, in Table 1
19, 23, 24, sample Nos. 28, 29, 34 in Table 2).

Further, when the ratio of zirconium oxide exceeds 10% by weight with respect to the main component, ΔR25 also exceeds 5% (for example, Sample No. 17, 22, 2 in Table 1).
7, see Sample No. 33, 39 in Table 2).

[0024]

According to the present invention, a composition containing manganese, nickel and copper oxides having a certain composition ratio as a main component,
By adding an appropriate amount of zirconium oxide, it is possible to obtain a highly reliable thermistor composition having a very small rate of change in resistance even when used under conditions of high temperature and high humidity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazushi Saito 1-13-1, Nihonbashi, Chuo-ku, Tokyo Inside T-DK Co., Ltd. (72) Keiichi Kato 1-1-13-1, Nihonbashi, Chuo-ku, Tokyo No. T-Day-K Co., Ltd.

Claims (1)

[Claims] 1. The ratio of only metal elements is 15 to 20% manganese.
55 mol%, nickel 15-85 mol%, copper 0.01-3
A composition for a thermistor, characterized in that 0.01 to 10% by weight of zirconium oxide is added to an oxide consisting of 0% by mole and the total amount thereof is 100% by mole.