JPH0661016A - Thick film thermistor composition and manufacture thereof as well as thick film thermistor using same and manufacture thereof - Google Patents

Abstract

PURPOSE:To suppress the fluctuation in thermal resistance of added Cu for reducing the resistance value while sustaining the B constant by a method wherein a compound composed of at least two kinds of either one combination of oxide, hydroxide and carbonate of Cu, and Ru, Ru as the second, conductive material is added to the thick film thermistor material. CONSTITUTION:A thick film thermistor body 3 in sandwich type is printed and baked between electrodes 2, 2 vertically opposed on a substrate 1 so as to manufacture the thick film thermistor. At this time, a compound composed of at least two kinds of either one combination out of oxide, hydroxide and carbonate of Cu and Ru or Cu and Ru as the second conductive material mixed to be heated and baked is added to RuO2 as the first conductive material. Through these procedures, the thick film thermistor composition and thick film thermistor, low in the rate of change in thermal resistance value and high/B constant at low resistance, without losing the thermal resistance stability can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick film thermistor composition for a thick film thermistor formed by sandwich printing between electrodes on an insulating substrate, a method for producing the same, and a thick film thermistor using the composition. And a manufacturing method thereof.

[0002]

As a conventional thick film thermistor composition,
It is known that a metal oxide such as Mn, Co, Fe, and Ni having thermistor characteristics, RuO ₂ as a conductive material, and glass powder are further mixed. Then, there is a sandwich-type thick film thermistor in which this composition is superposed on a part of a first electrode formed on an insulating substrate and printed, and a second electrode is superposed on the composition.

This sandwich type thick film thermistor can have a lower resistance value than a sheet-like thick film thermistor in which the thermistor composition is printed between electrodes on the same plane. However, even in this sandwich type thick film thermistor, the resistance value is limited to about 8 kΩ, and in order to obtain a resistance value less than that, RuO ₂ as the first conductive substance is further added, or Mn, Co, Further, Cu or Cu is directly added to a metal oxide having thermistor characteristics such as Fe and Ni.
An oxide (hereinafter abbreviated as Cu) was added.

In the conventional method of adding Cu to a metal oxide having thermistor characteristics to form an oxide, Mn, Co,
1000 ℃ so that Fe and Ni form a spinel structure
It is necessary to react at the above temperature. When Cu is added, Cu is incorporated into the spinel structure and Cu
Some produce compounds of either O or Cu ₂ O. Of these, Cu ₂ O is CuO if left for a long time.
Therefore, it is considered that the resistance value changes due to the respective changes of the crystal structure and the conductivity, or the strain. This means that the resistance change rate of the thermistor composition to which Cu is not added is about + 1% at 125 ° C. for 1000 hours, whereas that of Cu is 1
It is also known that a change of + 10% to + 15% occurs at 25 ° C for 100 hours.

Therefore, in order to solve this problem, it is conceivable to suppress the temperature to 1000 ° C. or lower when Cu is added. However, in the discrete type in which a conventional thermistor composition is press-molded and then fired and sintered, a spinel structure is not formed because a chemical reaction does not occur, and as a result, thermistor characteristics are not obtained, and further, it is not sintered. , Was mechanically fragile.

[0006]

When the added amount of RuO ₂ exceeds 7 wt% of the whole, the resistance value and the B constant (a constant for knowing the rate of change of the resistance value, generally B = 2000K to 5000).
K. ) And abruptly drop, making it unusable as a thermistor. Further, the method of directly adding Cu to the metal oxide having the thermistor property is a good method for lowering the resistance value, but the composition to which Cu is added lacks thermal stability and is +10 at 100 ° C. for 125 hours at 125 ° C. %
There is a problem that the resistance value changes by up to + 15%.

In view of the above problems, the present invention is a thick film thermistor composition capable of suppressing the heat resistance change of added Cu and having a high B constant, while lowering the resistance value, a method for producing the same, and this composition. A thick film thermistor using a material and a method for manufacturing the same are provided.

[0008]

Since the present invention has been made for the purpose of solving the above-mentioned problems, the following structure is provided as one means for solving the above-mentioned problems. That is, M
a mixture of at least two metal oxides having thermistor characteristics selected from the oxides of n, Co, Fe, and Ni, which are heated and baked; and RuO ₂ as a first conductive material, Cu and R as second conductive materials
u, or a compound obtained by mixing and heating at least two kinds of any combination of oxides, hydroxides, and carbonates of Cu and Ru, and glass.

Then, this is applied to a thick film thermistor.

[0010]

In the above structure, a thick film thermistor material made of RuO ₂ and glass as a first conductive material, which is obtained by mixing and heating at least two kinds of metal oxides having thermistor characteristics, and a second Cu as a conductive material
And Ru, or a combination of at least two of Cu and Ru oxides, hydroxides, and carbonates, which are mixed and heated and calcined, so that B with low resistance can be obtained.
A thick film thermistor composition having a high constant and heat resistance stability, and a thick film thermistor can be provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail below with reference to the drawings.

[0012]

First Example Mn ₃ O ₄ , Co ₃ O ₄ , and Fe ₃ O ₄ were mixed at a molar ratio of 1: 1: 0.2, molded, and heated and baked to obtain a solid-phase reaction. Metal oxide powder 31
wt% and RuO ₂ powder 4w as the first conductive substance
t% and CuO and RuO ₂ as the second conductive material are mixed in advance in a molar ratio of 1: 1 to obtain CuO and RuO _2.
The mixed powder of and was placed in a magnetic crucible and heated and baked at 900 ° C. for 1 hour to cause a solid phase reaction. When this powder was analyzed by X-ray diffraction, it was identified as a compound called CuRuO ₃ .
Then, 10 wt% of this powder and 55 wt% of lead borosilicate glass powder are weighed and mixed by an automatic mixer or a ball mill to form a mixture.

Here, butyl carbitol containing 7% by weight of ethyl cellulose as an organic vehicle was added so as to be 26% by weight of the mixture, and sufficiently mixed with a three-roll or the like to prepare a thick film thermistor paste. Using the obtained thick film thermistor paste, as shown in FIG. 1 and FIG. 2, heating and baking is performed between electrodes 2 and 2 which are vertically opposed to each other so as to have an opposed area of 0.25 mm ^2. The thick film thermistor body 3 was printed in a sandwich form so that the subsequent thick film had a thickness of 40 μm, and was baked at 850 ° C. for 10 minutes to obtain a thick film thermistor.

The resistance value of the obtained thick film thermistor is 109.
The resistance value change rate after heating at 125 ° C. for 1000 hours was + 2.08%, which was stable characteristics.

Table 1 shows the thick film thermistor sample 1 of the present invention.
The resistance values of B to B, the B constant, the rate of change in the resistance value at 125 ° C. for 1000 hours are shown. (However, sample 1 is 125 ° C; 100
This is the rate of change in resistance over time. )

In Table 1, the resistance value of each sample is a film thickness of 40 μm at 25 ° C. and a facing area of 0.25 mm ² , and the B constant is the natural value of the resistance value at 25 ° C. divided by the resistance value at 100 ° C. It is the logarithm of the reciprocal of the temperature difference.

In the above embodiments, CuO and RuO serving as the Cu source and Ru source serving as the second conductive material, respectively.
₂ was used, but a combination of other Cu compound and Ru compound may be used as long as it finally becomes an oxide of Cu and Ru. From Table 1, the thick film thermistor formed by using the composition of the present invention is Cu and Ru, or Cu and Ru oxide,
A compound obtained by mixing and heating at least two kinds of combinations of hydroxides and carbonates and heating the mixture without directly reacting with a metal oxide having a thermistor property is added to the compound, whereby low resistance and high B can be obtained. Has a constant, and 125
It is stable with little change in resistance value against heat of ℃. Therefore, by using the above-mentioned thick film thermistor composition, by printing and firing a thick film thermistor body in a sandwich form between electrodes that are vertically opposed to each other as a thick film thermistor, a low resistance is obtained. It is possible to obtain a thick film thermistor having a high B constant and excellent heat resistance stability.

[0018]

As described above, according to the present invention,
It is possible to obtain a thick film thermistor composition and a thick film thermistor which do not lack heat resistance stability, have a low resistance, a high B constant, and a small rate of change in resistance value with respect to heat. Further, since the metal oxide and the first and second conductive materials are mixed with the glass amount kept constant, a wide range of combinations of the resistance value and the B constant can be obtained by changing the addition amount of each. .

[Brief description of drawings]

FIG. 1 is a plan view of a thick film thermistor formed using the thick film thermistor composition of the present invention.

FIG. 2 is a vertical sectional view taken along line AA of the above.

FIG. 3 is a characteristic diagram of CuRuO ₃ addition amount and resistance value of the thick film thermistor of the present invention.

FIG. 4 is a characteristic diagram of CuRuO ₃ addition amount and B constant in the above.

[Explanation of symbols]

 1. Substrate 2. Electrode 3. Thick film thermistor body

[Table 1]

Claims (4)

[Claims] 1. A mixture of at least two metal oxides having thermistor characteristics selected from the oxides of Mn, Co, Fe, and Ni, which are mixed and heated, and as a first conductive material. RuO ₂ and a compound obtained by mixing and heating at least two of Cu and Ru as the second conductive substance or any combination of oxides, hydroxides and carbonates of Cu and Ru, and And a thick film thermistor composition. 2. A step of measuring and mixing at least two metal oxides having thermistor characteristics selected from the oxides of Mn, Co, Fe and Ni, mixing, heating and firing, and further crushing and weighing. , Ru as the first conductive material
Step B for weighing O ₂ and C as the second conductive material
a step C in which at least two kinds of oxides, hydroxides, and carbonates of u and Ru, or Cu and Ru are mixed and heated and calcined, and further ground and weighed;
Step D for weighing glass and the four steps A, B, C for weighing
And a thick film thermistor composition comprising an E step of manufacturing the thick film paste by mixing the powders obtained in D and a F step of heating and firing the thick film paste obtained in the E step. Method of manufacturing things. 3. The thick film thermistor composition according to claim 1 or 2 is formed by printing and firing so as to form a sandwich shape between electrodes formed on a substrate so as to face each other vertically. Thick film thermistor characterized by 4. A method for producing a thick film thermistor composition according to claim 2, a G step of printing first electrodes vertically opposed to each other on a substrate, and at least on the first electrodes. A step H of laminating and printing the thermistor composition so as to electrically connect to a part, and a second step to electrically connect to at least a part of the thermistor composition.
2. The method for producing a thick film thermistor, which comprises the step I of printing the electrode of step 1 and the step J of heating and firing the first electrode, the thermistor composition, and the second electrode together with the substrate.