JPH065404A - Thin film thermistor - Google Patents

Abstract

PURPOSE:To compose a thin film thermistor whose easy to handle sheetlike alumina substrate surface is perfectly covered with a baked glass cover layer by a method wherein the thin film thermistor element is contained in a recess formed in an insulating supporter. CONSTITUTION:A stainless sheet 15 and an insulating supporter 11 are brazed through the intermediary of an intermediate metallic sheet 13 having the intermediate thermal expansion coefficient between those of these elements 15 and 11. Next, a recession 12 having aperture parts on both ends thereof is formed on the surface of opposite brazed surface side of the supporter 11. Next, a thin film thermistor 10 is contained in this recession 12 so as to be covered with a baked glass covering layer 16 formed therein. Through these procedures, the title thin film thermistor whose easy to handle substrate surface is perfectly covered with the covering layer 16 while having a supporter causing no cracking at all can be composed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film thermistor, and more particularly to a thin film thermistor which can be easily mounted.

[0002]

2. Description of the Related Art Conventionally, a thin film thermistor of this type is shown in FIG.
As shown in FIG. 2, a pair of electrode films 2a, 2b of a thin film thermistor element, which is composed of a pair of electrode films 2a, 2b and a temperature sensitive resistor film 3 such as silicon carbide (SiC), on one surface of a flat alumina substrate 1. Is connected to a pair of lead wires 4a and 4b such as Pt thin wires (diameter of about 0.1 mm), and a baking glass coating layer 5 is further formed. [For example, Bai Nagai, et al. National Technical Report
eport) Vol. 29, (1983)]

[0003]

As shown in the above-mentioned conventional example, a pair of lead wires 4a, 4b such as Pt wires are connected to the pair of electrode films 2a, 2b. Since the SiC thin film thermistor has excellent heat resistance and has a resistance temperature characteristic suitable for detecting a wide temperature range, it has been put to practical use in an oven or the like as a temperature sensor used in a temperature range of 0 to 500 ° C. Therefore, a Pt wire and a Ni wire having excellent heat resistance are used as the pair of lead wires 4a and 4b, and the pair of lead wires 4a and 4b are usually welded to the pair of electrode films 2a and 2b, respectively. Connected. This is because the welded connection has excellent heat resistance. However, this welding strength is as weak as 10g or less, and the element is small (1.8mmx
Since it is about 6.5 mm x 0.5 mm), careful attention is required for welding work and subsequent handling. Therefore, there is a problem that a lot of working time is required and the price becomes high.

The baking glass coating layer 5 is a pair of electrode films 2.
It protects the a and 2b and the temperature sensitive resistor film 3, and also protects the welded portions of the pair of lead wires 4a and 4b. However, the baked glass coating layer 5 may not completely cover the end of the flat alumina substrate 1. In this case, for example, if dew condensation water adheres to the surface of the element or the surrounding components, the insulation between the pair of electrode films 2a and 2b and the ground is deteriorated, and there is a problem that malfunctions are likely to occur.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a thermistor structure which is easy to handle and in which the calcined glass coating layer completely covers the surface of the flat alumina substrate.

[0006]

In order to solve the above problems, the thin film thermistor of the present invention is insulated from a stainless steel plate through an intermediate metal plate having a thermal expansion coefficient intermediate between that of the stainless steel plate and the insulating support. And a thin film thermistor element is housed in the recess, and the thin film thermistor element is covered to form the insulating support. The baking glass coating layer is formed on the top.

[0007]

According to the present invention, since the thin film thermistor element is housed in the concave portion of the insulating support brazed to the stainless steel plate, the thermistor is connected after connecting the pair of lead wires to the pair of electrode films. An insulating support or a stainless steel plate having a larger area than the element can be handled, and the work becomes easy. Further, since the baking glass coating layer covers the thermistor element and further extends to the surface of the insulating support, the baking glass coating layer can completely cover the thermistor element.

[0008]

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 thin film thermistor of the present invention. The thermistor element 10 is housed in the recess 12 of the insulating support 11. At this time, the recess 12 extends to the end of the insulating support 11, and both ends thereof are open. After housing the thermistor element 10 in the recess 12, a pair of lead wires are connected to the thermistor element 10. Although the flat alumina substrate, the pair of electrode films, the temperature sensitive resistor film, and the pair of lead wires are omitted in FIG. 1, it goes without saying that these are configured in the same manner as the configuration shown in FIG. Is.

The insulating support 11 is made of ceramic such as alumina and has a diameter of 8 to 10 mm.
It may be disk-shaped or rectangular. The depth of the recess 12 is preferably about 2 to 3 times the thickness of the thermistor element 10. The insulating support 11 is brazed to the stainless steel plate 15 by the brazing material layer 14 via the intermediate metal plate 13. At this time, the coefficient of thermal expansion of the intermediate metal plate 13 is selected to be a value between the stainless plate 15 and the insulating support 11 such as alumina.
In this way, no cracks occur in the brazed insulating support 11, but the intermediate metal plate 13 is omitted,
When the insulative support 11 is directly brazed to the stainless steel plate 15, cracks are easily generated in the insulative support 11. Insulating support 11 made of ceramics such as alumina
Has a coefficient of thermal expansion of (40 to 100) × 10 ⁻⁷ , while the stainless steel plate 10 has a coefficient of thermal expansion of (100 to 80).
Since it is x10 ⁻⁷ , titanium metal or Kovar alloy is preferable as the intermediate metal plate 13.

When configured in this manner, the insulating support 1
Since No. 1 has an area that is 4 to 6 times as large as the area of the thermistor element 10, it is clear that handling after connecting the lead wires is easy. Further, at the time of this handling, the thermistor element 10 is not directly handled. For example, since the work of grasping the thermistor element 10 with tweezers is eliminated, the thermistor element 1 is
It is also possible to prevent the surface of 0 from being damaged. In addition, as shown in FIG. 1, the baking glass coating layer 16 is used for the thermistor element 10.
It will be apparent that the thermistor element 10 is completely covered with the calcined glass coating layer 16 since it covers the surface of the insulative support 11.

The intermediate metal plate 13 and the insulating support 11
It is preferable to provide a recess 17 in the stainless plate 15 at the portion to be brazed. This is because the recess 17 acts as a positioning for the intermediate metal plate 13 and the insulating support 11.

[0012]

As described above, according to the present invention, the following effects can be obtained. (1) Since the thermistor element is housed in the recess of the insulating support, the subsequent handling becomes easy. (2) Since the firing glass coating layer covers the thermistor element and extends to the surface of the insulating support, the thermistor element is completely covered with the firing glass coating layer. (3) Since the insulating support and the stainless steel plate are brazed to each other via the intermediate metal plate, no crack is generated in the insulating support.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a conventional thin film thermistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Thin film thermistor element 11 Insulating support 12 Recess 13 Intermediate metal plate 14 Brazing material layer 15 Stainless steel plate 16 Firing glass coating layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Ito 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A stainless steel plate and an insulating support body are brazed to each other through an intermediate metal plate having a thermal expansion coefficient intermediate between those of the stainless steel plate and the insulating support body, and the anti-brazing surface of the insulating support body. A thin film thermistor in which a concave portion is formed on the side surface, a thin film thermistor element is housed in the concave portion, the thin film thermistor element is covered, and a baking glass coating layer is formed on the insulating support. 2. The thin film thermistor according to claim 1, wherein the insulating support is alumina, and the intermediate metal plate is Kovar alloy or titanium metal. 3. The thin film thermistor according to claim 1, wherein a recess is provided in the stainless steel plate at the portion where the intermediate metal plate is brazed.