JPS60182701A - Thermistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a thermistor. More specifically, the present invention relates to a thermistor having excellent resistance-temperature characteristics and good response.

(b) Prior Art Conventionally, thermistors have been known as thermoelectric elements that utilize the fact that electrical resistance changes with temperature. This thermistor is known. This thermistor has a semiconductive metal oxide layer such as manganese, cobalt, nickel, copper, etc. formed between a pair of electrodes, and these are carbonates, nitrates, chlorides, oxides, etc. of the corresponding metals. It is formed by mixing them appropriately so as to obtain a predetermined resistivity and heating and sintering them at a high temperature. As specific shapes of the metal oxide layer, bead shapes, disk shapes, rod shapes, etc. are known.

However, since the thermistors obtained by these sintering methods are in the above-mentioned bulk form, they have a large heat capacity and therefore have a slow response, making it difficult to obtain one with excellent resistance-temperature characteristics.

In this regard, some proposals have been made to fabricate a thermistor with a small heat capacity by forming a thin metal oxide layer on an insulating substrate using sputtering, but it is difficult to control the composition in the case of a multi-component system using sputtering. There are also disadvantages in that it is difficult to control the resistance value within a desired range, and only a flat plate-like insulating substrate can be used.

09 Purpose This invention was made under the above circumstances, and it is an object of the present invention to provide a thermistor that has a small heat capacity, excellent resistance-temperature characteristics, and can be easily manufactured into a desired shape. be.

B) Structure According to the present invention, in a thermistor comprising a semiconductive metal oxide layer between a pair of electrodes, the metal oxide layer has a corresponding metal alkoxide and/or oxygen as a ligand. A thermistor is provided which is formed into a thin film by coating and forming a gel film produced by hydrolysis of an organometallic chelate compound on an insulating base material and then heat-treating the film.

The most distinctive feature of this invention is that a semiconductive metal oxide layer is first formed on an insulating substrate using a metal hydroxide gel film produced by hydrolysis and drying of a specific organometallic compound as an intermediate. The point is that it is formed by subjecting it to heat treatment.

Such a metal hydroxide-based gel film can be formed by coating an aqueous solution of the organometallic compound on an insulating substrate, so that the resulting metal oxide layer is significantly stronger than that obtained by conventional sintering methods. It is made into a thin film.

In this invention, an organometallic chelate compound having a corresponding metal alkoxide and/or oxygen as a ligand is a compound consisting of metal elements and their composition ratios corresponding to the metal composition of the intended semiconductive metal acid or compound. - or a plurality of the above compounds. The metal oxide layer is usually suitably composed of oxides of one or more metals selected from magnesium, vanadium, manganese, iron, cobalt, nickel, and copper; As for the organometallic chelate compound used as a ligand, one containing the above-mentioned metal is correspondingly used.

As a specific example of the above-mentioned metal alkoxide, it is suitable to use lower alkoxide metals, such as CO(OC2
H6)2, N1(OC2H5)2, Fe(OC2H5)
3 etc. are preferred. On the other hand, as specific examples of organometallic chelate compounds having oxygen as a ligand, metal chelate compounds of alkanedions or derivatives thereof are suitable, such as 2,4-pentanedione (acetylacetone), 3-phenyl-2 , 4-pentanedione (3-phenylacetylacetone), 2,4-hexanedione, 2,4 (or 3,5)-hebutanedione, 2,2,6,6-titramethyl-3,5-hebutanedione (dipy baloylmethane)
Preferred are manganese chelate compounds, cobalt chelate compounds, nickel chelate compounds, etc. of lower alkanedions such as. Of course, these may be mixed and used, and the combination will usually have a resistance value of 10° to
(on the order of 108Ω).

To obtain the thermistor of the present invention, first, a metal hydroxide-based gel film produced by hydrolysis of the organometallic compound is formed on an insulating substrate.

This formation is carried out by applying a water-containing solution of an organometallic compound onto an insulating substrate by a dipping method, a spinner method, a brush coating method, or the like, and then gradually drying it by air drying or the like. As the water-containing solution in this case, it is appropriate to use a water-containing easily volatile organic solvent solution such as water-containing methanol or water-containing ethanol, and the water content is preferably a small amount (usually 0.5 VoL% or less). Furthermore, it is preferable to add an acid to this solution from the viewpoints that a uniform true solution can be obtained, hydrolysis can be smoothly performed, and a film of uniform thickness can be formed.

Note that the thickness of the gel film and thus the thickness of the metal oxide layer can be controlled by appropriately adjusting the viscosity of the aqueous solution, but usually the concentration of the above compound in the aqueous solution is 0.05~
The content is preferably 0.1% by weight.

The metal alkoxide and/or organometallic chelate compound in the aqueous solution is hydrolyzed by water to form a sol mainly composed of metal hydroxide, and by drying this, a gel film is formed. Drying can be done by air drying, but the drying time is 50-1.
It is preferable to maintain the temperature at about 00° C. to sufficiently remove by-product lower alcohols and solvents. However, since drying is also carried out during the heat treatment described later, it is not necessary to carry out the drying completely.

By heat-treating such a gel film, the metal hydroxide and its low condensate constituting the gel are dehydrated, highly condensed, and converted into oxides, thereby forming the metal oxide layer of the present invention. The conditions for heat treatment are usually 500 to 1500°C and 0.
By selecting raw materials that are sufficient for about 1 to 5 hours, b.
Processing is possible at a relatively low temperature of 100°C or lower, particularly at a low temperature of about 500°C.

The thickness of the metal oxide layer of the thermistor of the present invention thus obtained is typically 0.01 to 10 μm, which is significantly thinner than that of the conventional one. The disadvantages due to the heat capacity of the oxide layer are therefore improved.

Note that it is practically preferable to form an insulating surface protection film on the surface of the formed metal oxide layer, and this is particularly desirable when a liquid or gas containing moisture is to be measured. This surface protective film may be any film that does not impede the thermistor characteristics and can prevent direct contact between the measurement target and the semiconductive oxide layer.
It is suitable to cover the surface with an insulating oxide film having a thickness of about 1/2 to 1/2.

This formation is preferably done by applying a solution of lower alkoxysilane and gelling it in the same manner as the semiconductive oxide layer.
This is done by heat treatment. Therefore, the present invention also provides the thermistor characteristics of such a three-layer structure.

Note that the electrode may be formed in advance on the insulating base material on which the gel film is coated, or may be formed after the metal oxide layer is formed.

This invention will be explained below with reference to examples, but the invention is not limited thereby.

(E) Example [Example 1] Jetoxy cobalt, jetoxy nickel and manganese acetylacetonate were each 1.5 molar
The mixture was mixed in a ratio of 6:40.5:57.9 so that the total amount was 0.02 mol, and the mixture was added to 100 mZ of methanol and refluxed at 80° C. for 2 hours to obtain a homogeneous solution. After adding IN hydrochloric acid 2- to this solution, it was coated on one side of a 10x20x1.5 quartz glass plate by a dip method, and then at room temperature.
By leaving it for about 10 minutes and air-drying it, a gel film with a thickness of about 0.1 μm mainly composed of cobalt, nickel, and manganese hydroxides was formed on one side of the quartz glass plate. The glass plate was placed in an electric furnace and heated at a high temperature of about 800°C for 1 hour to obtain an element in which the gel film was converted to an oxide film. By applying silver paint to form a pair of electrodes, a flat thermistor (1) as shown in Figures 1 and 2 is produced.
I got it. In the figure, (2) and f2+ are electrodes, (3) is a semiconductive metal oxide layer, (4) is an insulating base material, and (5) is a lead wire, respectively.

The temperature-resistance characteristics of the thermistor obtained in this way are the fourth
As shown in the figure, it was in good condition.

[Example 2] A glass tube (inner diameter 311 II 111
A semi-tetraelectric metal oxide layer was formed on a part of the inner surface in the same manner as in Example 1, and then an alcoholic solution of tetraethoxysilane was poured onto it to cause hydrolysis. An insulating glass protective film was formed by firing at about 500°C.

Next, silver paste is poured into holes with a diameter of 0.5 that are opened at both ends of the glass tube to form electrodes, thereby producing a tubular thermistor (1') of the present invention as shown in FIG.
I got it. In the figure, (3D indicates a protective film. This thermistor (1') is suitable for measuring the temperature of a fluid flowing inside a pipe.

The characteristics of the thermistor (1') described above were similar to those in Example 1.

(F) Effects As described above, the thermistor of the present invention is made of a thin metal oxide layer, and therefore has a small heat capacity and excellent resistance-temperature characteristics. Furthermore, the metal oxide layer is advantageous because it is easy to form and can be formed not only on a flat insulating substrate but also on any shape, such as a tubular shape, a curved surface, a protrusion, an uneven shape, etc. , it is possible to expand the degree of freedom in the structure of the thermistor itself. For example, it can be easily formed on the inner surface of a tubular insulating base material to form a flow type thermistor. Furthermore, since the thermistor of this invention is made from an organometallic compound, it is possible to reduce the heat treatment temperature, and since it can be handled as a solution during manufacturing, there is no need to make it into a paste, allowing for desired composition control and resistance value control. It has the advantage that it can be performed more easily.

[Brief explanation of the drawing]

FIG. 1 is a plan view illustrating the thermistor of the present invention, FIG. 2 is a sectional view of FIG. 1, FIG. 3 is a partial sectional view illustrating another specific example of the thermistor of the present invention, and FIG. FIG. 3 is a graph diagram illustrating the temperature-resistance characteristics of the thermistor of the present invention. 1) , (1')・・・・・・・・・Thermistor,
(2)・・・・・・・Electrode, (3)・・・・・・・
...Semiconductive metal oxide layer, (4)...
・Insulating base, (5)...Lead wire, 6
XJ・・・・・・Protective film. Figure 1 Figure 3 1'' Figure 4 1og ('c)

Claims (4)

[Claims] (1) In a thermistor comprising a semiconductive metal oxide layer between a pair of electrodes, the metal oxide layer is capable of hydrolyzing a corresponding metal alkoxide and/or an organometallic chelate compound having oxygen as a ligand. A thermistor formed into a thin film by applying and forming a gel film produced by the method on an insulating base material and then heat-treating the film. (2) The thermistor according to claim 1, wherein the metal oxide layer has a thickness of about 0.01 to 10 μm. (3) The thermistor according to claim 1, wherein the metal oxide layer comprises an oxide or oxide of one or more metals selected from magnesium, vanadium, manganese, iron, cobalt, nickel, and copper. (4) The thermistor according to claim 1, wherein the organometallic chelate compound having oxygen as a ligand is a metal complex of alkanedions.