JPH0749271A - Contact type temperature sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a contact type temperature sensor of such constitution as to have large insulating distance and rapid heat responsiveness, and the manufacturing method thereof. CONSTITUTION:A temperature sensing unit 21 is formed of a thermistor 17 disposed in contact with one surface of a plate like supporting body 19, a lead wire 18 connected to the thermistor 17, and burned glass 20 covering the thermistor completely. The other surface of the plate like supporting body 19 of this temperature sensing unit 21 and the bottom face inner wall 5 of a bottomed metal container 4 are soldered with titanium foil 23 held between silver solder 22, 22' with a fusing point lower than the burning temperature of the burned glass 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type temperature sensor for mechanically contacting a surface of an object to detect its surface temperature and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, this type of contact type temperature sensor has a thin film thermistor 1 and silver brazing foils 2 and 2 '.
After being brazed directly to the bottom inner wall 5 of the bottomed metal container 4 by the sandwiched titanium foil 3, the lead wires 6 and 6'are connected, and further the thin film thermistor 1 is protected from the external environment by baking glass. 7 is formed. The thin film thermistor 1 is formed by forming electrode films 9 and 9'on one surface of an insulating substrate 8 and then forming a temperature sensitive resistor film 10.
The bottom surface outer wall 11 of the bottomed metal container 4 is mechanically brought into contact with the surface of an object to detect the surface temperature (for example, Japanese Patent Laid-Open No. 57-169202).

[0003]

The conventional contact-type temperature sensor has a high-speed thermal response due to the above structure. However, in the above-described configuration, the electrical insulation distance between the lead wires 6 and 6'and the bottom inner wall 5 of the bottomed metal container 4 depends on the thickness of the insulating substrate 8 (usually about 0.5 mm). Since it is determined, there is a problem that the insulation distance is short, that is, the electrical insulation is small. In particular, in a high humidity environment such as rainy season, dew condensation water easily adheres to the side surface of the insulating substrate 8 and insulation deterioration becomes a problem. SUMMARY OF THE INVENTION The first object of the present invention is to solve the above-mentioned conventional problems while maintaining high-speed thermal response, and to provide a structure having a better insulation performance than the conventional one. When the insulating substrate 8 having a large surface area is formed and the electrode films 9 and 9'and the temperature sensitive resistor film 10 are formed on the small surface area of the central portion of the surface,
The insulation distance can be increased. However, when the temperature-sensitive resistor film 10 is formed by the sputtering method or the vapor deposition method, the area that can be formed is limited. Therefore, such a configuration has a drawback that the number of the thin film thermistors 1 that can be formed is reduced and is practically used. The current situation is that there are none.

In the conventional contact type temperature sensor, the thin film thermistor 1 is brazed to the inner wall 5 of the bottom surface of the bottomed metal container 4 and then the lead wires 6 and 6'are connected or the baking glass 7 is used. Had formed. However, since the thin film thermistor 1 is located closer to the bottom inner wall 5 side than the apex portion 13 of the side wall 12 of the bottomed metal container 4, these connecting and forming operations are hindered by the side wall 12 of the bottomed metal container 4. It
As a result, these operations require skill and it is difficult to automate the operations. A second object of the present invention is to provide a structure that facilitates these operations and a structure that can be automated.

[0005]

As a first technical means for achieving the above-mentioned first object, a thermistor fixed in contact with one surface of an insulative flat plate-like support, and connected to the thermistor Forming a temperature sensitive unit with the lead wire and the calcined glass that entirely covers the thermistor, and has a melting point lower than the calcining temperature of the calcined glass between the other surface of the flat support and the inner wall of the bottom surface. The brazing is done with a titanium foil sandwiched between waxes.

As a second technical means, a thermistor fixed in contact with one surface of the flat support, a lead wire connected to the thermistor, and a baking glass covering the entire surface of the thermistor. Forming a temperature sensitive unit,
The metal container is made of titanium and is brazed between the other surface of the plate-shaped support and the inner wall of the bottom surface with silver brazing material having a melting point lower than the baking temperature of the baking glass.

A third aspect for achieving the above second object
As a technical means of arranging a thermistor to which a lead wire is connected on one surface of the flat plate-shaped support, and drying the baked glass paste in a state where it is entirely covered with the other surface of the flat plate-shaped support. Between the inner walls of the bottom surface, a silver brazing foil having a melting point lower than the firing temperature of the glass paste, a titanium foil, and a silver brazing foil are laminated, and the thermistor is fixed to a metal container in a heating step of firing the glass paste in an inert gas atmosphere. It is configured.

As a fourth technical means, a thermistor to which a lead wire is connected is arranged on one surface of the flat plate-like support, and a temperature-sensing unit is obtained through drying and baking with the baking glass paste entirely covered. After forming, between the other surface of the flat plate-shaped support and the bottom inner wall,
The thermistor is fixed to a metal container in a heating process in which a silver brazing foil having a melting point lower than the firing temperature, a titanium foil, and a silver brazing foil are laminated and heated to a temperature lower than the firing temperature in an inert gas atmosphere.

[0009]

The present invention provides a contact-type temperature sensor having excellent insulation performance because the insulation distance becomes extremely large by the above-mentioned first and second technical means and the thermal response is not different from the conventional one.

The first and third technical means can be used.
Also, the second technical means can be easily realized, and the work of making the temperature-sensitive unit does not need to be performed in the bottomed metal container.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first and second technical means of one embodiment of the present invention will be described below with reference to FIGS. The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. A thin film thermistor 17 including a pair of electrode films 15 and 15 'and a temperature sensitive resistor film 16 was prepared on one surface of the flat alumina substrate 14. The flat alumina substrate 14 has a width of 2 mm, a length of 4 mm, and a thickness of 0.5 mm.
Is. The pair of electrode films 15 of the thin film thermistor 17
After connecting a pair of lead wires 18 and 18 'to 15' respectively, a thin film thermistor 17 is attached to the flat plate alumina support 19.
Then, the thin film thermistor 17 was entirely covered to form the baking glass 20 to form the temperature sensitive unit 21. The work of forming the temperature-sensitive unit is performed on the surface of the flat plate-shaped alumina support 19, so that the work is easy and can be automated.

The electrode films 15 and 15 'are made of a thick film conductive paste, for example, Ag paste, Ag-Pd paste, A.
It is formed by printing u-Pt paste or the like and then firing it at a high temperature of 800 ° C. or higher. As the temperature-sensitive resistor film 16, various materials such as a composite metal oxide, a vapor deposition film of Ge, Si and SiC, a sputtered film, a baked thick film, etc. are used.
The C sputter temperature-sensitive resistor film is excellent in that it has a heat resistance of 500 ° C. and a resistance temperature characteristic suitable for detecting a wide temperature range of 0 to 500 ° C. The baking glass 20 is formed by covering the entire periphery of the thin film thermistor 17 with a thick film glass paste and baking at a high temperature of 700 ° C. or higher. The thickness of the baking glass 20 is 1 to 3 mm. The shape of the flat plate-shaped alumina support 19 is selected to be larger than that of the flat plate-shaped alumina substrate 14, and here, the diameter is 10 mm,
The thickness was 0.5 mm.

After forming the temperature-sensitive unit 21, the other surface of the flat plate-shaped alumina support 19 and the inner bottom surface 5 of the bottomed metal container 4 made of stainless steel are attached to the baking glass 20.
The brazing was performed with a titanium foil 23 sandwiched between silver solders 22 and 22 'having a melting point lower than the firing temperature of. A silver brazing material having a melting point of 700 ° C. or lower, for example, silver brazing JIS standard number BAg1 (liquidus temperature about 620 ° C.), BAg-2 (liquidus temperature about 700 ° C.), BAg-3 (liquid phase) Line temperature about 69
0 ° C) is suitable.

With this configuration, the present invention allows the shape of the flat plate-shaped insulating support 19 to be selected larger than that of the thin film thermistor 17. A thin film thermistor 17 is provided substantially in the center of a flat alumina support 19 having a diameter of 10 mm and a thickness of 0.5 mm.
, The electrical insulation distance between the lead wires 18 and 18 'and the bottom inner wall 5 of the bottomed metal container 4 was 3 to 4 mm. In this way, the insulation distance is
The size can be easily increased 5 times or more (2.5 mm or more) compared to about 0.5 mm). As a result, high insulation can be easily obtained.

The thermal response of the contact type thermistor of the present invention was measured as follows. First, the outer bottom surface 11 of the bottomed metal container 4 of the contact type temperature sensor kept at room temperature (T ₀ ° C)
Is the time when the temperature of the thermistor 17 reaches T ₀ +0.9 (T−T ₀ ), starting from the point of contact with the bottom of an aluminum pan filled with hot water (T ° C., about 95 ° C.). The thermal response was evaluated by (90% response time). The 90% thermal response time of the conventional contact type temperature sensor is 4 to 5 seconds,
That of the present invention was 5-6 seconds. The thermal resistance of the element portion from the thin film thermistor 17 of the contact-type temperature sensor of the present invention to the outer bottom surface 11 of the bottomed metal container 4 is mainly due to the thickness of the flat insulating support 19 as compared with the conventional one. Since only the thermal resistance increases, the thermal response becomes slow. But,
The above-mentioned practical 90% thermal response time is strongly influenced by the contact thermal resistance between the pan and the outer bottom surface 11 of the bottomed metal container 4, and the thermal response time due to the thermal resistance of the element is small. As a result, the thermal response time of the contact type thermistor of the present invention is considered to show only a delay of about 1 second as compared with the conventional one. This delay is not a problem in practice.

The above description is about the case where the bottomed metal container 4 made of stainless steel is used, but the case where the bottomed metal container 24 made of titanium is used is shown in FIG. As described above, there is an advantage that a simple brazing structure is sufficient. That is, the bottom inner wall 5 of the bottomed metal container 24 made of the flat insulating support 19 and titanium can be brazed only with the brazing material 22. However, titanium is inferior in mechanical strength to stainless steel, so
Practical applications are limited to some extent.

Further, the above description is based on the thin film thermistor 1.
7 is used, but it is clear that the same thing can be done by using a metal oxide thermistor, for example. However, since the metal oxide thermistor usually has a cylindrical shape or a shape similar thereto, when the metal oxide thermistor is arranged on the surface of the flat plate-shaped insulating support 19, the two make line contact with each other. On the other hand,
Since the thin film thermistor 17 has a plate-like shape, the two are in surface contact with each other. For this reason, heat conduction is achieved by the thin film thermistor
Are superior to metal oxide thermistors.

Next, the third and fourth technical means will be described. The baking glass 20 is usually manufactured through a glass baking step in which a thick film glass paste is applied to a predetermined place and then heat-treated at a high temperature. The firing temperature of this glass firing process is 7
It is preferably about 00 ° C. If the firing temperature is higher than this, the characteristic change of the thermistor 17 before and after the firing becomes significantly large, and if the firing temperature is lower than this, the heat resistance of the firing glass 20 is required for the contact temperature sensor of the present invention.
This is because the heat resistance at 0 ° C. cannot be satisfied and cracks easily occur. On the other hand, brazing is also performed through a brazing firing process in which heat treatment is performed at a high temperature in an inert gas atmosphere. Therefore, in the manufacture of the contact type temperature sensor of the present invention, the thermistor 17 and the lead wires 18 and 18 'connected to the thermistor 17 are arranged on one surface of the flat plate-shaped insulating support 19, and then the thermistor 17 is arranged. Is entirely covered with a glass paste for thick film and dried in air at about 100 ° C., then, between the other surface of the flat insulating support 19 and the bottom inner wall 5 of the bottomed metal container 4, After laminating the silver brazing foil 22, the titanium foil 23, and the silver brazing foil 22 ′ having a melting point of 700 ° C. or less, the laminated body is heated to about 700 ° C. in an inert gas atmosphere, and thus the glass firing of the firing glass paste is performed. It is preferable that the step and the temperature-sensing unit and the brazing and firing step of the bottom inner wall 5 of the bottomed metal container 4 are simultaneously processed in one heating step. Thereby, the manufacturing process can be simplified. However, this manufacturing process is not general because it requires a thick film glass paste that can be fired in an inert gas atmosphere.
That is, a general thick film glass paste is usually fired in air. For firing in an inert gas atmosphere, it is necessary to change the resin component contained in the paste to an appropriate resin component. Such special pastes are limited in types and are not common.

In such a case, in the manufacture of the contact type temperature sensor of the present invention, the thermistor 17 and the lead wires 18 and 18 'connected to the thermistor 17 are arranged on one surface of the flat insulating support 19. Next, the thermistor 17 is entirely covered with a thick film glass paste, dried in air at about 100 ° C., and then fired in air at about 700 ° C. to form a temperature-sensitive unit, and then the flat plate-shaped insulation is used. A melting point of 700 ° C. is formed between the other surface of the flexible support 19 and the bottom inner wall 5 of the bottomed metal container 4.
After laminating the following silver brazing foil 22, titanium foil 23 and silver brazing foil 22 ', the laminated body is placed in an inert gas atmosphere at 700
It is preferable that the temperature sensitive unit and the bottom inner wall 5 of the bottomed metal container 4 are brazed by heating at a temperature of not higher than ° C.
This manufacturing process does not require any special paste. In addition, the manufacturing process of the conventional contact type temperature sensor, that is, after brazing the thin film thermistor 1 to the bottom inner wall 5 of the bottomed metal container 4, the lead wires 6 and 6 ′ are connected, and then the baking glass 7 is used.
The manufacturing process of the present invention is easier to perform than the manufacturing process of forming the structure, and the process can be automated. In the conventional manufacturing process, since the thin film thermistor 1 is located closer to the bottom inner wall 5 side than the apex portion 13 of the side wall 12 of the bottomed metal container 4, these connecting and forming operations are performed on the side wall of the bottomed metal container 4. Blocked by 12. As a result, these operations require skill and it is difficult to automate the operations. In the manufacturing process of the present invention, brazing can be performed after the temperature-sensitive unit is prepared in advance. Since the work of forming the temperature-sensitive unit is performed on the surface of the flat plate-shaped insulating support 19, there is no obstacle to the work, the work of connecting the lead wires and the work of forming the baking glass are facilitated, and the work is automated. It will be possible.

[0020]

As described above, the following effects can be obtained by the first technical means of the present invention.

(1) Since the shape of the flat insulating support can be selected larger than that of the thermistor element, the insulation distance is 5 times or more (2.5 mm or more) as compared with the conventional one (usually about 0.5 mm). Can be easily enlarged. As a result, high insulation can be easily obtained.

When insulation deterioration occurs in the contact type temperature sensor,
For example, if the temperature of the pan bottom is detected on a gas table and the heating power is adjusted, there is a drawback that premature cutting may occur and cooking may not be possible. To do.

(2) Since the thermistor element and the inner bottom surface of the bottomed metal container are brazed to each other via the flat insulating support, the thermal resistance between them can be kept small. As a result, high-speed thermal response can be secured.

Next, according to the second technical means, the bottomed metal container is changed from stainless steel to titanium, the material cost is a little high, and the mechanical accuracy is a little inferior, so the application is limited to some extent. Since the titanium foil 23 is unnecessary, it is extremely easy to fix the temperature-sensitive unit and the bottomed metal container.

Next, by the third and fourth technical means, the first
And the second technical means can be easily realized. That is, since the melting point of silver solder is selected to be lower than the baking temperature of the baking glass, the brazing can be performed after the temperature-sensitive unit is prepared in advance by performing the brazing temperature at a temperature lower than the baking temperature of the baking glass. The work of creating the temperature sensitive unit is
Since the work is performed on the surface of the flat insulating support, there is no obstacle to the work, the work of connecting the lead wire and the work of forming the baking glass are facilitated, and the work can be automated.

Although the glass paste is special in the third technical means, it is extremely economical because it can be produced by one firing step, and is extremely advantageous when the number is large. Further, the fourth technical means requires two firing steps, but is advantageous when the quantity is small because no special paste is required.

[Brief description of drawings]

FIG. 1 is a sectional view of a contact-type temperature sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a contact type temperature sensor according to another embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional contact-type temperature sensor.

[Explanation of symbols]

 4 Bottomed Metal Container 5 Bottom Inner Wall 11 Bottom Outer Wall 17 Thermistor (Thin Film Thermistor) 18 Lead Wire 19 Flat Plate Support 20 Firing Glass 21 Temperature Sensing Unit 22, 22 'Silver Wax 23 Titanium Foil

Front page continued (72) Inventor Shuji Ito 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A bottomed metal container having a thermistor fixed to the inner wall of the bottom surface and a contact surface contacting the object to be measured on the outer wall of the bottom surface, and a flat plate-shaped support for insulating the metal container and the thermistor. A temperature sensitive unit is formed by a thermistor fixed in contact with one surface of a flat plate-shaped support, a lead wire connected to the thermistor, and a baking glass that entirely covers the thermistor. A contact-type temperature sensor configured to be brazed between the other surface of the body and the inner wall of the bottom surface with a titanium foil sandwiched between silver brazing fillers having a melting point lower than the firing temperature of the firing glass. 2. A bottomed metal container having a thermistor fixed to an inner wall of the bottom surface and a contact surface contacting an object to be measured on an outer wall of the bottom surface, and a flat plate-like support for insulating the metal container from the thermistor, A thermistor fixed in contact with one surface of the flat plate-shaped support, a lead wire connected to the thermistor, and a baking glass that entirely covers the thermistor form a temperature sensitive unit, and the metal container is A contact-type temperature sensor formed of titanium and brazed between the other surface of the plate-shaped support and the inner wall of the bottom surface with silver brazing having a melting point lower than the firing temperature of the firing glass. 3. The contact type temperature sensor according to claim 1, wherein the thermistor is a thin film thermistor. 4. A bottomed metal container having a thermistor mounted on the inner wall of the bottom surface and having a contact surface for contacting the object to be measured on the outer wall of the bottom surface, and a flat plate-shaped support for insulating the metal container and the thermistor, After placing a thermistor to which a lead wire is connected on one surface of the flat plate-shaped support and drying it in a state where the baking glass paste is entirely covered, between the other surface of the flat plate-shaped support and the inner wall of the bottom surface. , A silver brazing foil having a melting point lower than the firing temperature of the glass paste, a titanium foil, and a silver brazing foil are laminated, and the thermistor is fixed to the metal container in the heating process of firing the glass paste in an inert gas atmosphere. Manufacturing method. 5. A bottomed metal container having a thermistor mounted on the inner wall of the bottom surface and having a contact surface for contacting an object to be measured on the outer wall of the bottom surface, and a flat plate-shaped support for insulating the metal container and the thermistor. After a thermistor having lead wires connected to one surface of the flat plate-shaped support is arranged and a temperature sensitive unit is formed through drying and baking in a state where the baking glass paste is entirely covered, the flat plate-shaped support is Between the other surface and the inner wall of the bottom surface, a silver brazing foil having a melting point lower than the firing temperature, a titanium foil, and a silver brazing foil are laminated, and a thermistor is used in a heating step of heating to a temperature lower than the firing temperature in an inert gas atmosphere. Method for manufacturing a contact-type temperature sensor in which a metal is fixed to a metal container.