JPH0541304A - Metallic oxide group thermistor material - Google Patents

Abstract

PURPOSE: To inexpensively and safely obtain a metal oxide thermistor material having satisfactory characteristics by using iron oxide and titanium oxide in place of cobalt oxide and using zinc oxide in plane of copper oxide. CONSTITUTION: This metal oxide thermistor material is made to have a basic composition of aMnCO3 +bNiO+dZnO+eCo3 O4 +fFe2 O3 +gTiO2 and a composition ratio of 27.86<=a<=41.85, 6.17<=b<=10.97, 0<=d<=47.02, 0<=e<=8.97, 4.13<=f<=51.14 and 0.23<=g<=3.09 in weight ratio (provided a+b+d+e+f+g=100). In an oxide mixing method generally used widely by using such a material, an NTC thermistor is produced. Thus, expensive cobalt oxide is replaced with inexpensive iron oxide or titanium oxide, so production costs can be economized and further, since the use of copper oxide as harmful materials is excluded, stability in production work can be secured.

Description

Detailed Description of the Invention

[0001]

This invention relates to MnCO ₃ --NiO--
_{ZnO-Co 3 O 4 -Fe 2} O 3 -TiO 2 system or M
_{nCO 3 -NiO-CuO-ZnO-} Co 3 O 4 -Fe
_{The present invention} relates to a metal oxide based thermistor material having a basic composition of ₂ O ₃ —TiO ₂ system.

[0002]

2. Description of the Related Art In general, a thermistor is a kind of semiconductor element whose resistance changes extremely greatly and non-linearly with a change in temperature. In addition, the manufacturing method is mainly iron (F
It is obtained by mixing oxides such as e), nickel (Ni), manganese (Mn), molybdenum (Mo) and cobalt (Co) and sintering.

In particular, a metal oxide thermistor manufactured by combining transition metal oxides is a semiconductor element (NTC) whose electric resistance exponentially decreases with an increase in temperature. Since the crystal structure and the sinterability largely change depending on the sintering temperature, a large difference occurs between 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 temperature sensitive elements, temperature compensation and adjustment elements, and voltage adjustment elements.

Conventional metal oxide-based thermistor materials include
A spinel-based manganese-nickel-cobalt-copper system and a hematite-based iron-titanium system are used. In the former spinel-based thermistor, a wide resistance range can be obtained depending on the composition, and a large B constant. It is known to have a wide range of applications [reference: 1. Thermistors (ed. By E.
D. Macklen), Electrochemica
l Pub. , Ayr, Scottland (197
9). 2. Semiducting tempe
rature sensors and their
applications (ed.by HB Sa
chse), John and Wiley, New
York (1975). 3. Ceramic Mate
rias for electronic (ed.b
yR. C. Buchanan), Marcel De
Kker, New York (1986)].

[0005]

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

It is an object of the present invention to provide a metal oxide type thermistor material which has good characteristics safely and at low cost.

[0007]

[Means for Solving the Problems]
Therefore, the present invention has the following configurations. (1) The metal oxide-based thermistor material is aMnCO₃+ BNiO + dZnO + eCo₃O_Four+ F
Fe₂O₃+ GTiO ₂The system is the basic composition, and the composition ratio is
The quantitative ratio is 27.86 ≤ a ≤ 41.85 6.17 ≤ b ≤ 10.97 0 ≤ d ≤ 47.02 0 ≤ e ≤ 8.97 4.13 ≤ f ≤ 51.14 0.23 ≤ g ≤ 3.09 (however, a + b + d + e + f + g = 100).

(2) The metal oxide type thermistor material is aMnCO ₃ + bNiO + cCuO + dZnO + eCo
₃ O ₄ + fFe ₂ O ₃ + gTiO ₂ system is the basic composition,
The composition ratio by weight is 21.90 ≤ a ≤ 53.68 7.15 ≤ b ≤ 13.56 0 ≤ c ≤ 50.76 0 ≤ d ≤ 35.05 0 ≤ e ≤ 30.61 0 ≤ f ≤ 38.26 0 ≤ g ≤ 4.17 (however, a + b + c + d + e + f + g = 100). To be there.

That is, the present invention uses inexpensive iron oxide and titanium oxide in place of expensive cobalt oxide as the metal oxide thermistor material, thereby lowering the manufacturing cost of the thermistor material and harming the human body. By using harmless zinc oxide instead of pure copper oxide, avoid the pollution problem at the time of manufacturing thermistor material, and further, by eutectic reaction that occurs in multi-component oxide system, liquid phase sintering And the sintering temperature is lowered to safely produce a thermistor having good characteristics at a low production cost.

[0010]

EXAMPLE The composition of such a metal oxide thermistor material of the present invention is aMnCO ₃ (manganese carbonate) + bNi
O (nickel oxide) + cCuO (copper oxide) + dZnO
(Zinc oxide) + eCo ₃ O ₄ (Cobalt oxide) + fFe
_The basic composition is ₂ O ₃ (iron oxide) + gTiO ₂ (titanium oxide), and the compositional ratio by weight is as follows.

29 ≦ a + b ≦ 66 0 ≦ c + d ≦ 48 0 ≦ e + f + g ≦ 54 (where a + b + c + d + e + f + g = 100) Further, this can be represented by a three-component system as shown in FIG.

Using such materials, an NTC thermistor is manufactured by a generally widely used oxide mixing method. The manufacturing process of the thermistor will be specifically described below based on 60 embodiments. First, the material is
For, as shown in FIGS. 2 and 3, aMnCO <sub>3
+ BNiO + dZnO + eCo 3 O</sub> 4 + fFe 2 O 3 +
The basic composition is gTiO ₂ and the composition ratio is 27.86 ≤ a ≤ 41.85 6.17 ≤ b ≤ 10.97 0 ≤ d ≤ 47.02 0 ≤ e ≤ 8.97 4.13 ≤ f ≤ 51.14 0.23 ≤ g ≤ 3.09 (however, a + b + d + e + f + g = 100). ) Is a metal oxide.

Further, in Examples 31 to 60, as shown in FIGS. 4 and 5, aMnCO ₃ + bNiO + cCuO.
_{+ DZnO + eCo 3 O 4 +} fFe 2 O 3 + gTiO 2
21.90 ≤ a ≤ 53.68 7.15 ≤ b ≤ 13.56 0 ≤ c ≤ 50.76 0 ≤ d ≤ 35.05 0 ≤ e ≤ 30.61 0 ≤ f ≤ 38.26 0 ≤ g ≤ 4.17 (however, a + b + c + d + e + f + g = 100).

Then, these manganese carbonate, nickel oxide, copper oxide, zinc oxide, cobalt oxide, iron oxide and titanium oxide were accurately weighed with an accuracy of 10 ^-4 g, and sufficiently weighed with distilled water in a zirconia ball mill. Mix and grind. As the raw material used at this time, the following calcination (c
In the calcination step, a compound that can be easily converted into an oxide, such as a hydroxide or a carbonate, may be contained.

Next, the sample that had been mixed and ground was 750.
After calcination at ℃ ~ 850 ℃, add a small amount of general binder such as polyvinyl alcohol (PVA) aqueous solution, press-mold at 1 ton / cm ² pressure, and place on an alumina plate. Then, it is sintered in an electric furnace at a temperature of 1000 to 1200 ° C. for 2 hours. During sintering, organic substances such as a binder volatilize, so the temperature is maintained at 600 ° C. for 1 hour, and the heating and cooling rates are set to 300 ° C./hr.

Then, silver paste is screen-printed on both sides of the sintered body to form electrodes, heat-treated at 550 ° C. for 10 minutes, and allowed to stand for 24 hours, after which electrical characteristics are measured. Measuring the electrical properties of a specimen is done at various temperatures (eg 25 ° C and 85 ° C
(2) in the silicon oil thermostat set to (° C) by the two-terminal method, and the B constant (a constant representing the magnitude of resistance change with respect to temperature between two arbitrary temperatures in the resistance-temperature characteristic) is calculated by the following formula. .. Here, R25 ℃ and R85 ℃ are 25 ℃
And the resistance value at 85 ° C is shown.

B = {ln (R85 ° C./R25° C.)} / (1 / 358.155 −1 / 298.155) FIGS. 2 to 5 show the specific resistance, B constant and sintering temperature for each example. In addition, in FIG. 6, Examples 2, 3, 21, 28, 36, 3
The relationship between temperature and specific resistance is shown for 8, 42, 46, 50, 51, and 59. The metal oxide-based thermistor of the present invention obtained through such a manufacturing process has a spinel-based structure.
Also, as shown in FIG. 3, even if a considerable amount of iron oxide and titanium oxide are added, they are sufficiently dissolved to form a solid solution, and an excellent thermistor having a wide resistance range can be manufactured.

Therefore, the metal oxide-based thermistor material of the present invention can reduce the manufacturing cost of the thermistor by replacing the expensive cobalt oxide in whole or in large part with inexpensive iron oxide and titanium oxide. By eliminating the use of copper oxide, which acts as a harmful substance during the manufacture of the thermistor, the stability of the manufacturing operation can be ensured. Then, as shown in FIGS. 4 and 5, when copper oxide is added, the addition amounts of cobalt oxide, iron oxide and titanium oxide can be greatly changed, so that the resistance range should be adjusted in a wide range. And the B constant can be increased.

On the other hand, in the metal oxide type thermistor material of the present invention, a eutectic reaction occurs with each other in a multi-component composition, which causes sintering at 1000 to 1200 ° C. The sintering temperature can be lowered by about 100 ° C. to 250 ° C. as compared with the sintering temperature of the cobalt-copper based thermistor, and the manufacturing cost of the thermistor can be reduced also in this respect.

[0020]

As described above, according to the present invention,
By replacing all or most of expensive cobalt oxide with inexpensive iron oxide and titanium oxide, the production cost of the thermistor can be reduced, and even if iron oxide and titanium oxide are added in a considerable amount, it is sufficient. As a solid solution, it is possible to manufacture an excellent thermistor with a wide resistance range.

Further, by eliminating the use of copper oxide which acts as a harmful substance during the production of the thermistor, the stability of the production work can be ensured. Further, when copper oxide is added, the addition amounts of cobalt oxide, iron oxide and titanium oxide can be greatly changed, so that the resistance range can be adjusted in a wide range and the B constant can be increased. You can

Further, the sintering temperature can be lowered by about 100 ° C. to 250 ° C. as compared with the sintering temperature of the conventional manganese-nickel-cobalt-copper thermistor, and also in this point, the manufacturing cost of the thermistor can be reduced. be able to.

[Brief description of drawings]

FIG. 1 is a diagram of a three-component system showing a composition ratio of a metal oxide-based thermistor material used in an example according to the present invention.

FIG. 2 is a diagram showing the material composition and electrical characteristics of Examples 1 to 15.

FIG. 3 is a diagram showing the material composition and electrical characteristics of Examples 16 to 30.

FIG. 4 is a diagram showing the material composition and electrical characteristics of Examples 31 to 46.

FIG. 5 is a diagram showing the material composition and electrical characteristics of Examples 47 to 60.

FIG. 6 is a diagram showing the relationship between the temperature and the specific resistance of the thermistor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Lee, Korea 199-1 Sangmun-dong, Dobong-gu, Dobong-gu, Seoul, Republic of Korea

Claims (2)

[Claims] 1. AMnCO₃+ BNiO + dZnO + eC
o₃O_Four+ FFe₂O₃+ GTiO ₂The system has a basic composition
However, the composition ratio is 27.86 ≤ a ≤ 41.85 6.17 ≤ b ≤ 10.97 0 ≤ d ≤ 47.02 0 ≤ e ≤ 8.97 4.13 ≤ f ≤ 51.14 0.23 ≤ g ≤ 3.09 (however, a + b + d + e + f + g = 100). Characteristic metal oxide thermistor material. 2. AMnCO ₃ + bNiO + cCuO + dZ
The basic composition is nO + eCo ₃ O ₄ + fFe ₂ O ₃ + gTiO ₂ system, and the composition ratio by weight ratio is 21.90 ≤ a ≤ 53.68 7.15 ≤ b ≤ 13.56 0 ≤ c ≤ 50.76 0 ≤ d ≤ 35.05 0 ≤ e ≤ 30.61 0 ≤ f ≦ 38.26 0 ≦ g ≦ 4.17 (however, a + b + c + d + e + f + g = 100) A metal oxide thermistor material.