JP2913518B2 - Metal oxide thermistor material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a MnCO-NiO-Z
The present invention relates to a metal oxide-based thermistor material having a basic composition of nO-FeO-TiO.

[0002]

2. Description of the Related Art In general, a thermistor is a kind of semiconductor device whose resistance changes very largely and non-linearly with a change in temperature. The production method is mainly iron (F
e), oxides such as nickel (Ni), manganese (Mn), molybdenum (Mo) and cobalt (Co) are mixed and sintered.

[0003] In particular, a metal oxide thermistor manufactured by combining a transition metal oxide is a semiconductor device (NTC) whose electric resistance decreases exponentially with increasing temperature. Since the crystal structure and the sinterability greatly change depending on the sintering temperature, a large difference occurs in the room temperature resistance and the resistance change with temperature. Utilizing these characteristics, it is widely used as a core element of various precision measuring instruments and analytical instruments such as a temperature sensing element, a temperature compensation and adjustment element, and a voltage adjustment element.

[0004] Conventional metal oxide thermistor materials include:
A spinel-based manganese-nickel-cobalt-copper system and a hematite-based iron-titanium system are used. In the case of the former spinel thermistor, a wide resistance range is obtained depending on the composition, and a large B constant is obtained. Are known to be widely applicable [Ref: 1. Thermistors (ed. By E.E.
D. Macclen), Electrochemical
l Pub. , Ayr, Scotland (197
9). 2. Semiconducting tempe
ratture sensors and their
applications (ed. by HB Sa
chse), John and Wiley, New
York (1975). 3. Ceramic Mate
reals for electronic (ed.b
yR. C. Buchanan), Marcel De
kker, New York (1986)].

[0005]

However, such a spinel-based manganese-nickel-cobalt-copper thermistor is disadvantageous in terms of manufacturing cost because the price of cobalt oxide is very high. was there. In addition, when copper oxide is absorbed by the human body, it acts as a harmful substance that is harmful to human health, so that there is a problem that pollution occurs during the production of the thermistor [see: Ha].
wley's reinforced chemical
dictionary, 11th edition
(Ed.by NL Sax and RJ Le
wis, Sr. ) Van Nostrand Rein
hold Co. , New York (1987)].

An object of the present invention is to provide a metal oxide-based thermistor material having good properties safely and inexpensively.

[0007]

In order to achieve the above object, the present invention has the following arrangement. The metal oxide thermistor is aMnCO ₃ + bNiO + dZnO + fFe ₂
The basic composition is O ₃ + gTiO ₂ , and the composition ratio is a weight ratio. So that

That is, the present invention uses inexpensive iron oxide and titanium oxide instead of expensive cobalt oxide as the metal oxide-based thermistor material, thereby lowering the manufacturing cost of the thermistor material and causing harm to the human body. The use of harmless zinc oxide instead of pure copper oxide avoids the pollution problems associated with the production of thermistor materials and furthermore, the liquid phase sintering due to the eutectic reaction occurring in the multi-component oxide system. , And by lowering the sintering temperature, a thermistor having good characteristics can be manufactured safely at low manufacturing cost.

[0010]

The composition of the metal oxide thermistor material of the present invention is as follows: aMnCO ₃ (manganese carbonate) + bNi
O (nickel oxide) + dZnO (zinc oxide) + fFe ₂
The basic composition is O ₃ (iron oxide) + gTiO ₂ (titanium oxide), and the composition ratio is as follows by weight ratio.

[0011] Also, when this is represented by a three-component system, as shown in FIG. 1, the point a1
It becomes the range surrounded by ~ a6. However, points a5 and a6
Does not include 0.

Using such a material, an NTC thermistor is manufactured by an oxide mixing method generally used widely. Hereinafter, a manufacturing process of the thermistor concrete to. First, the materials are shown in FIG.
In _{Suyo, aMnCO 3 + bNiO + dZnO +} fFe
₂ O ₃ + gTiO ₂ is used as a basic composition, and the composition ratio is a weight ratio, For reference, Co ₃ O ₄ is contained in the above composition range.
2 and 3 as Reference Examples 1-21.
did.

Similarly, for reference, in order to clarify the characteristics of the thermistor material of the present invention when the value of the composition ratio d of ZnO is near 0 in the above composition range, the case where ZnO is not included (d = 0) as Reference Examples A to C
As shown in FIG . FIG. 4 shows Reference Example 2 containing copper oxide.
2 to 37 are shown.

Then, these manganese carbonate, nickel oxide, copper oxide, zinc oxide, cobalt oxide, iron oxide and titanium oxide are accurately weighed with an accuracy of 10 ⁻⁴ g and sufficiently mixed with distilled water in a zirconia ball mill. Mix and grind. The raw material used at this time may include a compound that can be easily converted to an oxide in the next calcination step, such as a hydroxide or a carbonate.

Next, the mixed and crushed sample is 75%.
After calcination at 0 ° C. to 850 ° C., a small amount of a general binder such as an aqueous solution of polyvinyl alcohol (PVA) is added, and the mixture is pressure-formed at a pressure of 1 ton / cm ² , and then placed on an alumina plate. Place and 1000-1200 ° C in electric furnace
Sintering at a temperature of 2 hours. During sintering, organic substances such as a binder are volatilized. Therefore, the temperature is maintained at 600 ° C. for 1 hour, and the rate of temperature rise and cooling is 300 ° C./hr.

Thereafter, silver paste is screen-printed on both sides of the sintered body to form electrodes, heat-treated at 550 ° C. for 10 minutes, left for 24 hours, and then measured for electrical characteristics. Measurement of the electrical properties of the specimen is performed at various temperatures (for example,
25 ° C and 85 ° C) in a silicone oil bath set at 2
This is performed by the terminal method, and the B constant (constant representing the magnitude of the resistance change with respect to the temperature between any two temperatures in the resistance-temperature characteristics) is calculated by the following equation. Here, R25 ° C and R85 ° C indicate resistance values at 25 ° C and 85 ° C.

B = {1n (R85 ° C./R25° C.)} /
(1 / 358.155 / 298.155) FIGS. 2 to 4 show the specific resistance, the B constant, and the sintering temperature of each of the examples and the reference examples . 2 to 4, the composition c is
The composition e indicates copper oxide (CuO), and the composition e is cobalt oxide (Co
₃ O ₄ ). The metal oxide-based thermistor of the present invention obtained through such a manufacturing process has a spinel-based structure .
As shown in FIG. 2, even if a considerable amount of iron oxide and titanium oxide are added, the solid solution is sufficiently formed, and an excellent thermistor having a wide resistance range can be manufactured.

[0018] Thus, the metal oxide-based thermistor material of the present invention, can save the manufacturing cost of the thermistor by replacing expensive oxide cobalt at a low iron oxide and titanium oxide, further, the manufacture of the thermistor By eliminating the use of copper oxide, which sometimes acts as a harmful substance, the stability of the manufacturing operation can be ensured. In addition, as shown in FIG. 4 , when copper oxide is added , the addition amounts of iron oxide and titanium oxide can be greatly changed.
The resistance range can be adjusted over a wide range, and the B constant can be increased.

On the other hand, in the metal oxide-based thermistor material of the present invention, a eutectic reaction occurs mutually in a multi-component composition, whereby sintering is carried out at 1000 to 1200 ° C. The sintering temperature can be reduced by about 100 ° C. to 250 ° C. as compared with the sintering temperature of the cobalt-copper thermistor. In this respect, the manufacturing cost of the thermistor can be reduced.

[0020]

As described above, according to the present invention,
Expensive cobalt oxide can save the manufacturing cost of the thermistor by alternative low-Ren iron oxide and titanium oxide, also it is sufficiently dissolved even when the iron oxide and titanium oxide are added considerable amounts An excellent thermistor with a wide resistance range can be manufactured.

Further, Ru can ensure the stability of the manufacturing operations by eliminating the use of copper oxide which acts as a harmful substance in the production of a thermistor.

Furthermore, the sintering temperature of the conventional manganese-nickel-cobalt-copper thermistor is 100 ° C. to 250 ° C.
The sintering temperature can be lowered by about ℃, and also in this regard, the manufacturing cost of the thermistor can be reduced.

[Brief description of the drawings]

3 Figure component system showing the composition ratio of Rukin genus oxide thermistor material written to the present invention; FIG

FIG. 2 is a view showing a material composition and electrical characteristics of Examples 1 to 3 and Reference Examples 1 to 9 ;

FIG. 3 is a view showing the material composition and electrical characteristics of Reference Examples 10 to 21 and AC .

FIG. 4 is a view showing a material composition and electrical characteristics of Reference Examples 22 to 37 .

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hong Ki-ryong 40, Osuku-ku-tei-dong, Gangnam-gu, Seoul, Republic of Korea References JP-A-56-160007 (JP, A) JP-A-56-33801 (JP, A) JP-A-64-12501 (JP, A) JP-B-25-2242 (JP, B1) JP-B Sho-A 27-4778 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01C 7/04 C01G 53/00 A C04B 35/00 J

Claims (1)

(57) [Claims] 1. aMnCO ₃ + bNiO + dZnO + fF
e ₂ O ₃ + gTiO ₂ system as a basic composition, and the composition ratio is a weight ratio, A metal oxide thermistor material characterized by the following.