JPH07122404A - Thick film thermistor composition, manufacture thereof, and thick film thermistor using the composition and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture the title thick film thermistor composition and thick film thermistor in low resistance and high B constant by a method wherein at least one kind out of Cu, Cu oxide, Cu hydroxide and Cu carbonate to be sintered later is to be added to a mixture of at least two kinds of metallic oxides to be sintered later having thermistor characteristics and a thick film thermistor material comprising RuO2 and glass. CONSTITUTION:The title thick film thermistor composition is composed of a mixture to be sintered later comprising at least two kinds of metallic oxides having the thermistor characteristics selected out of respective oxides of Mn, Co, Fe, Ni, an oxide to be sintered later comprising at least one kind of RuO2 as the first conductive material, Cu, Cu oxide, Cu hydroxide and Cu carbonate as the second conductive material and a thick film thermistor composition comprising glass. Through these procedures, the thick film thermistor composition and thick film thermistor in low resistance and high B constant as well as in less heat resistance value rate of change 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, or 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 a part of the composition is printed on a first electrode formed on an insulating substrate by superimposing and a second electrode is further formed thereon.

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 lower than that, RuO ₂ as the first conductive material is further added, or Mn, Co, Further, Cu or C can be directly added to a metal oxide having thermistor characteristics such as Fe and Ni.
u 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 Cu if left for a long time.
Since it oxidizes to O, it is considered to cause a change in resistance value due to changes in crystal structure and conductivity, strain, or the like. 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 thermistor characteristics is a good method for lowering the resistance value, but the composition to which Cu is added lacks thermal stability and is +10 at 125 ° C. for 100 hours.
There is a problem in that the resistance value changes from% 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, it has the following constitution 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 and mixed and sintered; and RuO ₂ as the first conductive material, The second conductive material is composed of an oxide obtained by firing at least one of Cu, Cu oxide, Cu hydroxide, and Cu carbonate, and glass.

Then, this is applied to a thick film thermistor.

[0010]

In the above structure, a thick film thermistor material composed of a mixture of at least two metal oxides having thermistor characteristics and sintering, a first conductive material of RuO ₂ and glass, and a second As a conductive material, Cu,
Thick film thermistor composition having low resistance, high B constant and heat stability, and thick film by adding at least one of Cu oxide, Cu hydroxide and Cu carbonate A 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]

Example 1 Metal obtained by solid phase reaction by mixing Mn ₃ O ₄ , Co ₃ O ₄ and Fe ₃ O ₄ in a molar ratio of 1: 1: 0.2, molding and firing. Oxide powder 31 wt%
And 4% by weight of RuO ₂ powder as the first conductive material
And 10% by weight of CuO as the second conductive material,
55 wt% lead borosilicate glass powder is weighed and mixed by an automatic mixer or a ball mill to form a mixture.

Here, as an organic vehicle, butyl carbitol containing 7 wt% of ethyl cellulose was added so as to be 26 wt% 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, after firing between the electrodes 2 and 2 which are vertically opposed to each other to have an opposed area of 0.25 mm ² as shown in FIGS. 1 and 2. The thick film thermistor body 3 was printed in a sandwich form so that the thick film of 40 μm was formed and baked at 850 ° C. for 10 minutes to obtain a thick film thermistor.

Resistance value 871 of the obtained thick film thermistor
Ω, B constant 2936K, 125 ° C, resistance value change rate after heating for 1000 hours was + 1.9%, which was stable characteristics.

Table 1 shows resistance values, B constant, 125 ° C., 1 of the thick film thermistor samples 2, 3, 4, 5 and 6 of the present invention.
The rate of change in resistance value at 00 hours or 1000 hours is shown.

In Table 1, Example 1 is heating for 100 hours, and Examples 2-6 is heating for 1000 hours. 12 for each
Heat resistance change at 5 ℃, resistance value at 25 ℃, film thickness 40μm
The facing area is a value of 0.25 mm ² , and the B constant is the natural logarithm of the resistance value at 25 ° C. divided by the resistance value at 100 ° C., and the difference of the reciprocal of those temperatures.

Although CuO is used as the second conductive material Cu source in the above embodiments, other Cu compounds may be used. As shown in Table 1, the thick film thermistor formed by using the composition of the present invention has a lower resistance than the conventional thick film thermistor by adding Cu separately without reacting with the metal oxide having thermistor characteristics. Has a high B constant, and is 1
It is stable with a small rate of change in resistance value with respect to heat of 25 ° C. Therefore, by using the above-mentioned thick film thermistor composition, a thick film thermistor body is printed and fired in a sandwich form between electrodes which are vertically formed on a substrate as a thick film thermistor, so that B It is possible to obtain a thick film thermistor having a high constant and excellent heat resistance stability.

[0018]

As described above, according to the present invention,
There is no decrease in B constant as in the case of mixing and molding with a metal oxide and preliminarily solid phase reaction (that is, sample No. 1 in Table 1), and there is no lack of heat stability. It is possible to obtain a thick film thermistor composition and a thick film thermistor which are high and have a low resistance change rate with respect to heat. In addition, the glass amount is kept constant and the metal oxide and the first,
Since the second conductive material is blended, a wide range of resistance values and B constants can be combined by changing the amount of each additive.

[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 CuO addition amount and resistance value of the thick film thermistor of the present invention.

FIG. 4 is a characteristic diagram of CuO addition amount and B constant as 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, mixed and sintered, and a first conductive material. RuO ₂ , a second conductive substance, an oxide obtained by firing at least one of Cu, Cu oxide, Cu hydroxide and Cu carbonate, and glass. Membrane thermistor composition. 2. At least two metal oxides having thermistor characteristics selected from the respective oxides of Mn, Co, Fe and Ni are weighed, mixed, fired, further crushed and weighed. At least one of Cu, Cu oxide, Cu hydroxide, and Cu carbonate as the second conductive material, and the A step, the B step of weighing RuO ₂ as the first conductive material, Finally, the Cu oxide is mixed, and the C step of weighing the Cu oxide, the D step of weighing the glass, and the powders obtained in the weighing 4 steps A, B, C and D are mixed to form a thick film. E step of manufacturing a film paste, and the E step
A method for producing a thick film thermistor composition, which comprises the step F of firing and sintering the thick film paste obtained in the step. 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 firing the first electrode, the thermistor composition, and the second electrode together with the substrate.