JPS58103102A - Thin film 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 The present invention provides a thermistor that detects temperature by mechanically contacting an object to detect 11 degrees. This relates to a thermistor for detection.

2. - Conventionally, this type of temperature detection has been carried out by mechanically bringing a thermocouple 2 into contact with the pot bottom 1 and detecting the thermoelectromotive force of the thermocouple 2, as shown in FIG. At this time, the thermocouple 2 was fixed to the support container 3 in order to bring the thermocouple 2 into strong mechanical contact with the pot bottom 1. However, the thermoelectromotive force usually has the disadvantage that only a small value can be obtained. For example, an alumel-chromel thermocouple has a heat resistance (600 to 100 in air).
0°C) and is inexpensive, but only generates an electromotive force of ~4oμv/°C. Copper-constantan thermocouple, platinum-
The thermoelectromotive force of a platinum Φ rhodium thermocouple is (30~eo)
Not only is it not possible to obtain μV/℃L, but the heat resistance is low (
copper-constantan thermocouple).

It had drawbacks such as being expensive (platinum-platinum-rhodium thermocouple). Various other thermocouples exist, but all of them have the drawbacks mentioned above. When controlling the amount of heat generated by a heat source by electrically detecting a small thermoelectromotive force as described above, a large electrical amplification is required, which increases the price. There were also disadvantages such as the need for complex electrical circuits.

Page 3 On the other hand, when temperature is detected using a thermistor instead of the above thermocouple, the rate of change in resistance value with respect to temperature is (1 to 7%/
℃) can be obtained. Therefore, it does not require a complicated electric circuit and has the advantage of being low cost. In this case, the thermistor element is selected to be as small as possible and to have a low heat capacity. This is because miniaturization allows for faster thermal response. Such small-sized thermistor elements include bead-type thermistor elements using composite oxide sintered bodies such as Fe, Ni, Co, and Mn as temperature-sensitive resistors, or composite oxides such as those mentioned above, Go,! There is a thin film thermistor element using a thin film of 3i, SiC, etc. as a temperature sensitive resistor. However, since the beat-type thermistor element usually has a shape similar to a sphere or a spheroid, there is a drawback that even if the thermistor element is fixed to the support container 3, the thermal resistance becomes large.

In other words, even if the thermistor element itself has a small heat capacity,
Due to its complicated shape, it is difficult to reduce the thermal resistance at the connection with the support container 3.

As a result, there was a drawback that the thermal response became slow.

On the other hand, since the thin film thermistor step can be connected to the support container 3 by brazing as shown in FIG. 2, it has the advantage of providing high-speed response. A thin film thermistor chip is usually constructed by forming an electrode film 5 and a temperature sensitive resistor film 6 on one surface of a flat ceramic insulating substrate 4 made of alumina or the like, and further, a lead wire 7 is connected to the electrode film 6. The brazed connection between the thin film thermistor tip and the support container 3 is made of getanium Ti.
This is done by using a brazing material layer 9 via a foil or zirconium Zr foil 8. However, in this case, since the electrode film 6 and the temperature-sensitive resistor film 6 are exposed to the external atmosphere, there is a drawback that characteristics change due to conductive dirt such as water droplets.

The present invention aims to protect the entire surface of the insulating substrate including the electrode film 6 and the temperature sensitive resistor film 6.

The gist of the present invention is to connect a thin film thermistor step, which is formed by forming an electrode film and a temperature-sensitive resistance film on one surface of a flat ceramic insulating substrate, to a support container by brazing via a titanium Ti foil or a zirconium Zr foil. , the entire surface of the flat ceramic insulating substrate on which the electrode film of the thin film thermistor chip and the temperature sensitive resistor film are formed has a coefficient of thermal expansion of (40 to 60) x 10.
0 As described above, in the fast-response thin-film thermistor of the present invention, the entire surface of the flat ceramic insulating substrate on which the electrode film and the temperature-sensitive resistor film are formed is electrically coated with glass of ""/C. Since it is coated with insulating glass, the thin film thermistor tip can be protected from conductive dirt such as water droplets.

At this time, the thermal expansion coefficient of glass is (40~e o ) x
It is desirable that the temperature is in the range of 1 o-'/°C. This is because by selecting a thermal expansion coefficient within this range, the glass coating film can form a dense film without cracks or pinholes.
This is because cracks and pinholes are likely to occur outside this range.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 3, the same numbers as mentioned above indicate the same members.

7 Lumina substrate 4 (1.8mWX 6.'6m L
A thick film electrode 6 (10 to 16 μm) and a SiG temperature sensitive resistor film 6 (
A thin film thermistor chip was constructed by forming 6 heges of 2 to 3 #mt). This thermistor tip and support container 3 (material S U 8-430°0.
4 wm t) were connected by brazing with a brazing material layer 9 (A g 7 Cu eutectic alloy) via a Ti foil (60 μm t) 8.

Next, connect the AU-Pt electrode film 6 with a lead wire? (Pt line.

0.1φ) were welded and connected. Furthermore, ZnO-B2O3-
Glass powder mainly composed of 81o2 (particle size 360 mesh or less), ethyl cellulose, diethylene glycol,
A mixed fluid with mono-fisted normal butyl ether acetate was separately prepared, and this fluid was applied over the entire surface of the thermistor tip. After this, the heating rate is about 1
The glass powder was fired at a temperature of 6°C/min, a maximum firing temperature of 660°C, a holding time of about 6 minutes at the maximum firing temperature, and a cooling rate of about 6°C/min. The glass coating film 1o formed in this way has a thickness of 0.2 to 0.6 m, and includes an electrode film 6 and a temperature-sensitive resistor film 6.
Cracks,
No pinholes were produced.

The resistance value of this thermistor changed after 1000 hours at 360°C in air, after 3000 heat cycles of 1.16 minutes at room temperature and 157 pesos at 350°C in air, and after being left in boiling water for 8 hours. The ratio was ±3% or less, and no cracks occurred even after these tests. Also,
The resistance value did not change even under conditions where condensation is likely to occur, such as in a high humidity atmosphere.

In addition, in this example, Zn0-B O81 was used as the glass material.
3 This is because when the temperature sensitive resistor film 6 is a SiC film, the short-term heat resistance of the SiC film in air is 600 to 750°C; This is because the firing temperature of the B 0-8in2 glass material is 650 to 740°C, which is excellent in that both have the same thermal properties.

Therefore, depending on the heat resistance of the temperature-sensitive resistor film 6, other glass materials such as Pbo-g2o3-sto2 may be used.

It is obvious that the At203-8iO2 type may also be used.

As is clear from the above description, the thin film thermistor of the present invention provides the following effects.

1. Since a glass coating film is formed over the entire surface of the flat ceramic insulating substrate on which the electrode film and temperature-sensitive resistor film are formed, the thin film thermistor tip can be protected from conductive dirt such as water droplets. 02. As mentioned above, coating is done using a mixed fluid of glass material and organic binder, but at this time, the amount of coating can be maintained at a constant level by controlling the viscosity of the mixed fluid. , the glass coating film is formed almost uniformly. As a result, the heat capacity of this thin film thermistor becomes almost uniform, so the thermal response can be made uniform. It is possible to improve the target strength.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a temperature detection configuration using a thermocouple, FIG. 2 is a cross-sectional view showing the configuration of a conventional fast-response thin-film thermistor, and FIG. 3 is a cross-sectional view of the fast-response thin-film thermistor of the present invention. FIG. 3 is a sectional view showing the configuration. 3... Support container, 4... Flat ceramic insulating substrate, 6-... Electrode film, 6... Temperature sensitive resistor film, 7... ...Lead wire, 8...
Ti foil or Zr foil, 9... Brazing material layer, 10
...Glass coating O Agent's name: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] 1. A thin film thermistor step formed by forming an electrode film and a temperature sensitive resistor film on one surface of a flat ceramic insulating substrate and a support container are connected by brazing via titanium foil or zirconium foil. The entire surface of the flat ceramic insulating substrate on which the electrode film and temperature-sensitive resistor film of the thin film thermistor step are formed has a coefficient of thermal expansion of (40 to 60)
10-', thin film thermistor coated with glass. 2. The thin film thermistor according to claim 1, wherein the glass coating is made of anine oxide, boron oxide, or silicon oxide.