JP2734840B2 - Contact type thin film thermistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface temperature sensor capable of detecting the surface temperature of an object by mechanically contacting the surface of the object, and more particularly to a contact type thin film usable up to a high temperature of 400 to 500.degree. It relates to a thermistor.

[0002]

2. Description of the Related Art Conventionally, a surface temperature sensor of this type is shown in FIG.
As shown in FIG. 1, lead wires 2 and 2 ′ are connected to a temperature detecting element composed of a glass-sealed thermistor 1, and the glass-sealed thermistor 1 is bonded to a metal plate 3 with a resin 4. The metal plate 3 is brought into mechanical contact with the surface of the object by screwing or the like, and the surface temperature is detected (for example, Japanese Patent Publication No. 60-125535).

[0003]

However, in the above configuration, the glass-sealed thermistor element 1 is bonded to the metal plate 3 with the resin 4, and the heat-resistant temperature of the resin 4 is usually about 200 ° C. or less. Therefore, the maximum operating temperature is about 20
There is a problem that the temperature is limited to 0 ° C. or lower.

Further, since the glass-sealed thermistor element 1 has a cylindrical shape, heat transfer between the metal plate 3 and the glass-sealed thermistor element 1 is poor, so that the thermal response is slow (90%). (The thermal response time is 20 sec or more).

The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to provide higher heat resistance and better high-speed response than before.

[0006]

In order to solve the above-mentioned problems, a contact type thin film thermistor according to the present invention comprises a thin film thermistor element, a pair of plate-like metal leads and an insulating support. Is a flat alumina substrate, a pair of through holes provided in the flat alumina substrate, electrically conductive from one surface to the other surface of the flat alumina substrate, penetrating through the through hole A pair of conductive members disposed, a pair of electrode films disposed including the through hole on the one surface of the flat alumina substrate, and a temperature-sensitive layer disposed on the pair of electrode films. A pair of plate-like metal lead wires are disposed so as to face the pair of through-holes on the other surface of the flat alumina substrate of the thin-film thermistor element. The conductive member and the pair of plate-shaped metal lead wires are respectively connected by an adhesive conductive sintered body, and the flat insulating support body has a glass film formed on one surface thereof, and the pair of plate-shaped metal lead wires is provided. The connected thin film thermistor element was disposed on one surface of the insulating support, and the thin film thermistor element including the pair of plate-shaped metal leads was covered with a sintered glass body around the thin film thermistor element. Things.

[0007]

According to the present invention, the above-mentioned structure does not use any organic material such as resin, so that the maximum use temperature is increased. That is, a flat alumina substrate, a glass sintered body,
Since the electrode film, the adhesive conductive sintered body, and the like are formed through a high-temperature firing step, higher heat resistance than before can be easily obtained. The same heat resistance can be easily obtained by using an alumina plate for the insulating support and a conductive sintered body for the conductive member. Therefore, the heat resistance of the thin film thermistor of the present invention ultimately depends on the heat resistance of the temperature-sensitive resistor film. The heat resistance is determined by the material and the forming conditions of the temperature-sensitive resistor film. For example, by using a SiC sputtered temperature-sensitive resistor film, a maximum operating temperature of 500 ° C. can be obtained.

Further, since the thin-film thermistor element has a flat plate shape, the heat transfer between the insulating support and the thin-film thermistor element is smaller than that between the conventional cylindrical glass-sealed thermistor element and the metal plate. Excellent, so that the thermal response is also fast.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of the contact type thin film thermistor of the present invention. A pair of through-holes 6a and 6b are provided at positions facing the flat alumina substrate 5. The shape of the flat alumina substrate 5 is 2 mm wide, 6 mm long,
The thickness was 0.5 mm, and the diameter of the pair of through-holes 6a and 6b was 0.5 mm. After printing a conductive paste for electrodes including a pair of through-holes 6a and 6b on one surface of the plate-like alumina substrate 5, drying and firing are performed to form a pair of Au-Pt thick film electrode films 7a and 7b. Thereafter, the conductive paste for through-holes is printed on the inner surfaces of the through-holes 6a and 6b or on the space, and then dried and fired to form the conductive members 8a and 8b. The pair of thick electrode films 7a and 7b and the pair of conductive members 8a and 8b are connected to each other by a pair of conductive members 8a so as to electrically conduct from one surface of the plate-like alumina substrate 5 to the other surface. , 8b are electrically connected. Examples of the conductive paste for the electrode and the conductive paste for the through-hole include Ag paste, Ag-Pd paste, and A
A u-Pt paste or the like is used. Thereafter, a silicon carbide (SiC) temperature-sensitive resistor film 9 is formed on one surface of the flat alumina substrate 5 by a sputtering method to form a thin-film thermistor element.

After the thin film thermistor element is formed in this manner, the other surface of the flat alumina substrate 5 contacts the conductive members 8a, 8b formed in the pair of through holes 6a, 6b to form a pair of connection members. A conductive paste is applied, and thereafter, a pair of plate-shaped metal lead wires 10a and 10b are adhered to the conductive paste for connection, and then dried and fired to form adhesive conductive sintered bodies 11a and 11b. At this point, an intermediate assembly is formed in which the pair of plate-like metal leads 10a and 10b are mechanically weakly coupled to the thin-film thermistor element. In addition,
As this conductive paste for connection, the same kind of paste as the conductive paste for electrode thin films is used.

On the other hand, an alumina insulating support 12 is prepared, and a fired glass film 13 is formed on one surface thereof. Thereafter, the above-mentioned intermediate assembly is laminated on the calcined glass film 13 formed on the plate-like alumina insulating support 12, and the periphery of the thin-film thermistor element including the pair of plate-like metal leads 10a and 10b is covered with glass. After coating with the paste, the glass sintered body 14 is formed by drying and firing. The thickness of the glass sintered body 14 is 1
２2 mm.

This thickness is about 100 times the thickness of a normal fired thick film formed through a printing process and a firing process. When the glass sintered body 14 having such a thickness is formed on the surface of the alumina insulating support 12 by a sintering step, the molten glass is hard to wet on the surface of the alumina insulating support 12 and thus easily becomes spherical. . This tendency is particularly remarkable when a metal that easily wets the glass is arranged in the molten glass. As a result, the bonding area between the alumina insulating support 12 and the glass sintered body 14 tends to decrease. In consideration of this point, in the contact type thin film thermistor of the present invention, the fired glass film 13 is formed on the surface of the alumina insulating support 12 in advance. Since the molten glass is easily wet on the fired glass film 13, a predetermined bonding area can be obtained. Fired glass film 13 and glass sintered body 14
Are the same in terms of wettability. Further, it is preferable that the fired glass film 13 is formed except for the peripheral end portion 15 of the alumina insulating support 12. When the fired glass film 13 is formed over one entire surface of the alumina insulating support 12, the sintered glass 14
When the amount is large, the glass sintered body 14 easily overflows from the alumina insulating support 12. However, when the fired glass film 13 is formed except for the peripheral end portion 15 of the alumina insulating support 12, as described above, the molten glass becomes the fired glass film 1.
This is because the glass sintered body 14 does not overflow from the alumina insulating support 12 because it wets well on the support 3 but does not easily wet on the alumina insulating support 12.

A pair of plate-like metal lead wires 10a, 1
0b, Fe-C having a width of about 1.2 mm and a thickness of about 0.3 mm
An r-based alloy plate is used. This alloy is excellent not only in heat resistance, but also in that it does not crack when coated with a glass sintered body 14 having the same thermal expansion coefficient as the alumina substrate 5.

In the contact-type thin film thermistor of the present invention thus constructed, since the organic matter such as resin is not used at all as compared with the conventional example, the maximum use temperature is set to 20.
0 ° C or higher. That is, the flat alumina substrate 5,
Since the electrode films 7a and 7b, the conductive members 8a and 8b, the adhesive conductive sintered bodies 11a and 11b, the glass sintered body 14, and the like are all inorganic substances and are formed through a firing step at 700 ° C. or more, , 500 ° C. or higher heat resistance can be easily obtained. Also, since an alumina plate is used for the insulating support 12, there is no problem with this heat resistance. Therefore, the heat resistance of the thin film thermistor of the present invention depends on the heat resistance of the temperature-sensitive resistor film 9 after all. This heat resistance is determined by the material of the temperature-sensitive resistor film 9 and the forming conditions. There are various types of temperature-sensitive resistor films 9 such as composite metal oxides, vapor-deposited films of Ge, Si, SiC, etc., sputtered films, and printed and fired thick films. It has excellent resistance-temperature characteristics that are suitable for detecting a wide temperature range of 0 to 500 ° C. Further, the contact type thin film thermistor of the present invention is brought into close contact with the surface of the object, and 90%
As a result of measuring the thermal response time, a high-speed thermal response of 7-8 sec was obtained.

[0015]

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

(1) Since it does not contain any resin used in the conventional surface temperature sensor and is entirely made of an inorganic material such as ceramic or sintered body, it is excellent in high heat resistance.

(2) Since the fired glass film is formed on the surface of the alumina insulating support, the adhesion between the glass sintered body and the alumina insulating sintered body can be stabilized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a contact type thin film thermistor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional surface temperature sensor.

[Explanation of symbols]

 6a, 6b Through-hole 7a, 7b Thick film electrode film 8a, 8b Conductive member 10a, 10b A pair of plate-like metal lead wires 11a, 11b Adhesive conductive sintered body 12 Insulating support 13 Fired glass film 14 Glass firing Union

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kenzo Koji 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-41002 (JP, A) JP-A-59 JP-A-195803 (JP, A) JP-A-2-180001 (JP, A) JP-A-5-234714 (JP, A) JP-A-4-293202 (JP, A) JP-A-4-293203 (JP, A) JP-A-4-293204 (JP, A)

Claims (3)

(57) [Claims] 1. A thin-film thermistor element, a pair of plate-like metal lead wires and a flat insulating support, wherein the thin-film thermistor element has a flat alumina substrate and a pair of through holes provided on the flat alumina substrate. Port, electrically conductive from one surface of the plate-like alumina substrate to the other surface, a pair of conductive members disposed through the through-hole, and the one of the plate-like amilna substrate A pair of electrode films disposed on the surface including the through-hole, and a temperature-sensitive resistor film laminated on the pair of electrode films; and the pair of plate-shaped metal lead wires is formed of the thin film. The other surface of the flat alumina substrate of the thermistor element is disposed so as to face the pair of through-holes, and the pair of conductive members and the pair of plate-shaped metal lead wires are respectively formed of an adhesive conductive sintered body. Contact with the body A glass film is formed on one surface of the flat insulating support, and the thin film thermistor element connected to the pair of flat metal leads is disposed on the one surface of the insulating support. A contact-type thin-film thermistor including the pair of plate-like metal leads and surrounding the thin-film thermistor element with a glass sintered body. 2. The contact type thin film thermistor according to claim 1, wherein the outer peripheral portion of one surface of the flat insulating support is a non-glass film. 3. The contact type thin film thermistor according to claim 1, wherein the glass film and the glass sintered body formed on one surface of the flat insulating support are made of the same material.