JP2652785B2 - Thermistor element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermistor element having excellent stability.

[Conventional technology]

Conventionally, a thermistor element using a sintered body of a transition metal oxide such as manganese, cobalt, and iron has been known.

The value of the B constant of a thermistor using a transition metal oxide such as iron, manganese, cobalt, or nickel is about 2,000 to 5,000. Therefore, near room temperature, if the temperature changes once, the resistance value changes by 2 to 5%. That is, it is possible to measure a temperature of about 1/100 ° C. by measuring a change in the resistivity of the thermistor.

For this reason, transition metal oxides such as iron, manganese, nickel, and cobalt are said to be suitable for thermistor materials used in temperature sensors at room temperature such as air conditioners, dryers, and electronic devices.

[Problems to be solved by the invention]

By the way, iron oxides, so-called ferrites, are particularly effective materials for thermistors, but as is well known, ferrite compounds have a variety of crystal structures, and depending on the type of crystal structure, the electrical reproducibility of the thermistor material may decrease. This causes a variation in electrical performance, and in practice, the amount of iron oxide added was limited to as little as possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermistor element which has no variation due to selection of a starting material and specification of a component mixing ratio and which has excellent reproducibility of electrical characteristics.

[Means for solving the problem]

In order to achieve the above object, a thermistor element according to the present invention is a thermistor element comprising a sintered body of manganese, cobalt and iron oxide, wherein the sintered body of manganese, cobalt and iron oxide is manganese carbonate, The oxide powder is sintered using cobalt carbonate and ferrous oxalate as constituent materials. The content of manganese, cobalt and iron metal elements contained in the sintered body is 11.0 to 40 mol% of manganese, cobalt 50 ~
It is combined with a total of 100 mol% within the range of 65 mol% and iron of 5 to 40 mol%.

〔Example〕

 Hereinafter, embodiments of the present invention will be described.

Manganese carbonate (MnCO _3), cobalt carbonate (2CoCO ₃ · 3Co
Each powder of (CH) ₂ ) and ferrous oxalate (FeC ₂ O ₄ .2H ₂ O) was weighed, and each amount was put into a ball mill and mixed for about 16 hours. This was dried, calcined at about 800 ° C. for 16 hours, and the powder was further mixed and pulverized with a ball mill and then dried to obtain an oxide powder. A butyl carbitol acetate solution containing ethyl cellulose was added to this oxide powder, processed into a paste, and this paste was stretched in parallel by a known method.
It was applied between the platinum wires to form a bead. After drying,
This bead was heated to about 1250 ° C. in air and baked for 30 minutes, and a platinum wire was cut between the beads to obtain a bead-type thermistor.

Manganese (Mn), cobalt (C
o), electrical characteristics of each of Examples 1 to 5 and Reference Example 1 were measured when iron (Fe) was set to the ratio (molar ratio) shown in Table 1. Table 1 also shows the resistance (KΩ) and the B constant (, K) at 25 ° C. for the thermistors of Examples 1 to 5 and Reference Example 1.

FIG. 1 shows a thermistor of each embodiment coated with glass,
It shows the measurement results of the rate of change in resistance when a standing test was performed at 250 ° C.

As is clear from FIG. 1, it can be seen that the rate of change in resistance is small and extremely stable in any of the examples.

In the present invention, a stable thermistor having a low resistance change rate in the range of 9.4 to 250 KΩ and a B constant of 3490 to 3920 ° K at 25 ° C. was obtained, as is apparent from each of the examples. , The resistance change rate ΔR25 was extremely stable at 0.05% or less. It was found that the same level of stability as in Example 3 could be obtained by properly setting the mixing ratio of cobalt and iron without necessarily adding manganese, but the resistance at 25 ° C. was significantly increased. Increased, and the B constant exceeded 5000 ° K. However, it can be seen that this blending example is effective in a two-component system.

As described above, manganese, cobalt,
In a ternary thermistor of iron, Mn is substantially 11 molar.
It is preferable to set the compounding ratio so that the total sum is 100 mol% in the range of 4040%, Co in the range of 50 to 65% and Fe in the range of 5 to 40%. The operation and temperature characteristics are stabilized by mixing each component within the above range, and a thermistor having an appropriate resistance value can be obtained. In addition, ferrous oxalate was selected as the iron component, and a fine particle distribution in which fine oxide powder was well dispersed could be realized, and thermistor characteristics could be stabilized and the change with time could be minimized.

〔The invention's effect〕

As described above, according to the present invention, it is possible to stabilize the electric characteristics by selecting the combination of the starting materials and specifying the ratio of the raw materials to be added, and thus to obtain a thermistor element excellent in reproducibility without fluctuations in the characteristics. This has the effect of providing an extremely stable element even at high temperatures.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change characteristic of a resistance change rate in an embodiment of the present invention.

Claims (1)

(57) [Claims] 1. A thermistor element comprising a sintered body of manganese, cobalt and iron oxide, wherein the sintered body of manganese, cobalt and iron oxide comprises manganese carbonate, cobalt carbonate and ferrous oxalate. The manganese, cobalt and iron metal elements contained in the sintered body are 11.0 to 40 mol% manganese and 50 to 65 cobalt.
A thermistor element characterized by being combined with a total of 100 mol% within a range of 5 mol% and 5 to 40 mol% of iron.