JPS62145803A - Manufacture of 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 Field of Industrial Application The present invention relates to a thermistor that detects temperature by mechanically contacting an object whose temperature is to be detected. The present invention relates to a method of manufacturing a thermistor that detects temperature.

2. Description of the Related Art This type of thermistor includes a fast-response thin film thermistor. This was reported in Nagai et al. [4th Sensor Symbodies Proceedings JP 245-249 (1984) sponsored by the Electronic Tepais Committee of the Institute of Electrical Engineers of Japan. This fast-response thin-film thermistor is constructed by brazing a thin-film thermistor element to a heat-sensitive metal container made entirely of stainless steel, and this brazing is accomplished as follows.

After placing a titanium foil sandwiched with eutectic silver solder foil between the thin film thermistor element and the heat-sensitive metal container, the thin film thermistor element is heated to approximately 820°C in vacuum. and heat-sensitive metal containers are brazed.

Problems to be Solved by the Invention In the above-mentioned brazing, the titanium foil sandwiched with the eutectic silver brazing foil is made by welding, but with this method, the time required to make the sandwiched foil is completely reduced. There was a problem in that the cost was high.

This is due to the fact that organic adhesives, which generate a large amount of vapor when heated in a vacuum, cannot be used to bond eutectic silver solder foil and titanium foil, and the clad material itself, which is made by cold or hot welding the two together. The reason is that it is not widely used industrially.

Furthermore, the aforementioned sandwich foil formed by welding has a problem in that the eutectic silver solder foil and the titanium foil constituting the sandwich foil tend to be misaligned, resulting in poor soldering conditions and impaired adhesion.

The present invention provides a method for manufacturing a thin film thermistor that eliminates all of the above-mentioned problems by using a printed film containing eutectic silver solder powder, titanium powder, and a binder as a brazing material.

Means for Solving the Problems The technical means of the present invention for solving the problems described above is that on one surface of the flat insulating substrate of the thin film thermistor element,
A printed film made of eutectic silver solder powder, titanium powder, and a binder is formed, and a heat-sensitive metal container is placed on top of the printed film, followed by heating in a vacuum.

Function As described above, the present invention has a configuration in which a printed film made of eutectic silver solder powder, titanium powder, and binder is formed on one surface of the flat insulating substrate of the thin film thermistor element, so that it is not necessary to use the conventional method. Moreover, there is no need to weld the eutectic silver solder foil and the titanium foil. Further, by using the printing method, the eutectic silver solder and titanium in the printed film are integrated, so there is no misalignment between the two, unlike in conventional welding of eutectic silver solder foil and titanium foil.

EXAMPLE Hereinafter, an example of the present invention will be described based on the attached drawings.
Let me explain.

FIG. 1 is a schematic cross-sectional view of the thin film thermistor of the present invention, showing the state before brazing by vacuum heating.

1 is a flat insulating substrate made of alumina or the like, and by forming a temperature sensitive resistor film 2 made of metal oxide, silicon carbide, etc. and a pair of electrode films 3 made of gold-platinum etc. on one surface of the substrate, a thin film thermistor is formed. The element is configured. On the other hand, on the other surface of the flat insulating substrate 1, a printed film 4 made of a mixture of eutectic silver solder powder 4a, titanium powder 4b, and a binder is formed. This printed film 4 includes, for example, 30 parts by weight of eutectic silver solder powder with a particle size of about 10 μm and 1 part of titanium powder with a particle size of about 70 μm.
A paste +- obtained by mixing and dispersing 15 parts by weight of a binder consisting of ethyl cellulose and calpitol.
It is obtained by screen printing, drying and firing.

Furthermore, after arranging the thin film thermistor element on top of the electric shock metal container 5 so that the printed film 4 is in contact with it, 104To
By heating to about 800 to 850°C in a vacuum below rr, the printed film 4 is melted and the heat-sensitive metal container 5 and the thin film thermistor element are bonded (
brazing).

The thin film thermistor manufactured in this way has the same high-speed response as the conventional example, and has excellent thermal shock resistance with no loss of adhesion even after 1000 cycles of (400°C) - water cooling tests. is obtained, and the performance is suitable for practical use.

The material for the heat-sensitive metal container 5 is as follows. Preferably, the material is selected from copal alloy, titanium, Kunkle, molybdenum, tungsten, stainless steel, iron-nickel alloy, and the like. This is because the coefficient of thermal expansion is similar to the coefficient of thermal expansion of ceramics such as alumina, steatite, and mullite used as the flat insulating substrate 1, so that the strain that occurs after brazing is reduced.

In addition, the particle size of the eutectic silver solder powder and titanium powder is 70 μm.
The following is desirable. When screen printing, a screen with a mesh size of 200 or more is preferable.
This is because the size of the openings in this mesh is approximately 74 μm.

Go to 7- Next, another embodiment of the present invention will be described using FIG. 2.

The difference in FIG. 2 from the previous embodiment lies in the structure of the printed film 4. In FIG. That is, on the other surface of the flat insulating substrate 1, a layer consisting of eutectic silver solder powder 4a and a binder, a layer consisting of titanium powder 4b and a binder, and a further layer consisting of eutectic silver solder powder 4a and a binder are screen printed. The printed film 4 is formed by four-dimensionally stacking Mi.

The thin film thermistor obtained by heating the thin film boomister element and the heat-sensitive metal container 5 in the same way as in the above example by brazing the entire thin film boomister element in a vacuum also had the same performance as that of the above example.

The reason why the flat insulating substrate and the heat-sensitive metal container that make up the thin film thermistor element are firmly brazed is that during the vacuum heat treatment process, titanium atoms move toward the surface of the flat insulating substrate made of titanium powder, alumina, etc. This is due to rapid diffusion and adsorption to the surface of the flat insulating substrate.

In fact, when brazing was attempted using only eutectic silver solder powder, it was confirmed that the flat insulating substrate and the heat-sensitive metal container were easily separated and could not be brazed.

In the present invention, the printed film is formed on the surface of the flat insulating substrate, but is not limited to this.
It may be formed on the surface of a heat-sensitive metal container.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) The eutectic silver solder powder and titanium powder, which are the brazing materials, are directly formed as a printed film on the surface of the flat insulating substrate by screen printing, so the eutectic silver solder foil and titanium foil can be welded as in the conventional method. There's no need.

(2) Since the printed film is formed by screen printing, the conventional problem of misalignment between the eutectic silver solder foil and the titanium foil is eliminated, and defects in soldering caused by this can be completely prevented.

(3) Has high-speed response and thermal shock resistance equivalent to conventional thin-film boomisters, making it highly practical.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a thin film boom 9 to 7 showing one embodiment of the present invention, and FIG. 2 is a sectional view of another embodiment of the same. 1... Flat insulating substrate, 4... Printed film, 4a... Eutectic silver solder powder, 4b...
Titanium powder, 5... Heat-sensitive metal container. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (3)

[Claims] (1) A thin film thermistor element consisting of a temperature-sensitive resistor film and a pair of electrode films formed on one surface of a flat insulating substrate is coated with metal powder and a binder on the other surface of the flat insulating substrate. A heat-sensitive metal container for fixing the thin-film thermistor element is placed on top of the printed film, and then heated to 800 to 850°C in a vacuum to remove the thin-film thermistor element and the heat-sensitive metal container. A method for manufacturing a thin film thermistor with brazed. (2) The method for manufacturing a thin film thermistor according to claim 1, wherein the printed film is a layer of a mixture of eutectic silver solder powder, titanium powder, and binder. (3) The thin film thermistor according to claim 1, wherein the printed film is a layer made of a eutectic silver solder powder and a binder, a layer made of a titanium powder and a binder, and a layer made of a eutectic silver solder powder and a binder. manufacturing method.