JPH01235302A - Glass-sealed thermistor - Google Patents

Abstract

PURPOSE:To enhance the reliability and heat restatance by a method wherein a base of a metal lead wire which can be sealed airtightly together with glass is connected to an electrode face of a thermistor bare body and the thermistor bare body is sealed airtightly by using the glass in such a way that the glass does not touch the thermistor bare body so that the thermistor bare body cannot be exposed directly to a high temperature during a glass sealing operation. CONSTITUTION:Lead wires 13a, 13b composed of Kovar (with a coefficient of thermal expansion of 50X10<-7> deg.C<-1>) are connected to a thermistor bare body 17 (with a coefficient of thermal expansion of about 85X10<-7> deg.C<-1>), composed of a transition metal oxide, where electrodes 12a, 12b have been formed on opposite faces; a glass tube 14 whose one end has been sealed in advance and which is composed of borosilicate lead glass (with a softening point of 785 deg.C and a coefficient of thermal expansion of 52,0X10<-7> deg.C<-1>) is covered. During this process, in order to prevent the glass tube 14 from touching the thermistor bare body 11, an opening part of the glass tube 14 is heated to 800 deg.C or higher and melted, and the thermistor bare body 11 is sealed airtightly into the glass tube 14. By this setup, the thermistor bare body can be sealed airtightly into the glass tube with a heat resistance of 500 deg.C or higher. During a glass sealing operation, a temperature of the thermistor bare body is increased to 500 deg.C or higher; the thermistor bare body is not deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a glass-encapsulated thermistor that is used as a temperature sensor for home appliances, housing equipment, automobile equipment, etc., and is particularly useful in fields where high heat resistance is required. It is something.

BACKGROUND OF THE INVENTION Conventionally, this type of glass-encapsulated thermistor has had a structure as shown in FIG. In FIG. 2, 1 is a thermistor element having electrodes 2a and 2b formed on opposing surfaces, and lead wires 3a and 3b are connected to the double-sided electrodes 2a and 2b, and the lead wire 31L.

The entire structure except for a part of 3b was hermetically buried in glass 4.

Problems to be Solved by the Invention This conventional configuration has the following problems.

(1) Since the glass is in contact with both the thermistor element and the lead wire, the thermal expansion coefficients of the thermistor element, lead wire, and glass must be matched, which poses a major constraint on component selection. In particular, high melting point glass has a small coefficient of thermal expansion and is not compatible with the thermistor element, and even if the glass is embedded, cracks may occur in the glass.

(2) When embedding glass, the molten glass comes into direct contact with the thermistor element, so the temperature of the thermistor element becomes higher than the glass melting point, and some thermistor elements suffer from thermal deterioration.

The present invention solves these problems by making it possible to select a glass and lead wire that have a different coefficient of thermal expansion than the thermistor body, and to use glass and lead wires that are compatible with the operating temperature and glass-enclosed atmosphere. Another object of the present invention is to provide a glass-encapsulated thermistor that has high reliability and heat resistance, since the thermistor element is not directly exposed to high temperatures during glass encapsulation.

Means for Solving the Problems In order to solve this problem, the glass-encapsulated thermistor of the present invention has an electrode surface of the thermistor body.

The base of a metal lead wire that can be hermetically sealed with glass is connected, and the thermistor element is hermetically sealed with glass so that the glass does not come into contact with the thermistor element.

Function: This configuration allows the selection of glass and lead wires with different thermal expansion coefficients for the thermistor element, and the operating temperature.
Glass suitable for glass-filled atmospheres.

Lead wires can be used, and the thermistor element is not directly exposed to high temperatures and deteriorated during glass encapsulation. Therefore, it is possible to provide a glass-encapsulated thermistor with high reliability and heat resistance.

Example An embodiment of the present invention will be described below.

FIG. 1 is a sectional view of a glass-encapsulated thermistor according to an embodiment of the present invention. In FIG. 1, a thermistor body 11 (thermal expansion coefficient Target 85 x 10 ℃
) is connected with a lead a13L113b made of Kovar (coefficient of thermal expansion 5ox1o'C), and made of lead borosilicate glass (softening point 786°C, coefficient of thermal expansion 52.0x10°C), which has been completely closed at one end in advance. glass tube 14
, and the glass tube 14 covers the thermistor body 11.
The opening of the glass tube 14 is set at 80° so as not to come into contact with the
The structure was such that the RiJ thermistor element body 11 was hermetically sealed inside the glass tube 14 by heating and melting it to 0° C. or higher. In this way, a glass-encapsulated thermistor shown in FIG. 1 was produced.

As described above, according to this embodiment, despite the combination of the thermistor element, lead wire, and glass tube that have significantly different coefficients of thermal expansion, the thermistor element is replaced with glass having a heat resistance of SOO°C or higher. Can be hermetically sealed within the
Moreover, even when the thermistor element is sealed in glass, the temperature of the thermistor element does not rise to 600° C. or higher, and the thermistor element does not deteriorate.

Therefore, it has a heat resistance of 500″C or more, high reliability,
This has the effect of providing a glass-encapsulated thermistor with high productivity.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained, and the practical value thereof is great.

(1) It is possible to select glass and lead wires that differ from the thermal expansion coefficient of the thermistor body, and the operating temperature can be improved.

Glass and lead wires suitable for the glass-enclosed atmosphere can be used, and as a result, the glass-encapsulated thermistor can be made highly heat resistant. Since it is not exposed to exposure and does not deteriorate, it is possible to improve the reliability of glass-encapsulated thermistors.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a glass-filled thermistor according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional glass-filled thermistor. 11...Thermistor element, 12a, 12b...
... Electrode, 13a, 13b ... Lead wire, 14
...Glass (glass tube). Name of agent: Patent attorney Toshio Nakao and 1 other person
(1, l2b-i 1.M l3b-1 Fig. 1 1.i-. Fig. 2 1-Minuta body scolding beast) - Do) Temple

Claims (1)

[Claims] The base of a metal lead wire that can be hermetically sealed with glass is connected to the electrode surface of a thermistor element having electrodes formed on opposing surfaces, and the glass A glass-encapsulated thermistor in which the thermistor body is hermetically sealed.