JPH0210801A - Manufacturing method of glass-encapsulated thermistor - Google Patents

Abstract

PURPOSE:To ensure heat resistance at a fixed temperature or higher continuously while easily welding-connecting a lead to an element assembly by connecting the tip sections of the leads plated with nickel and composed of an iron, nickel and cobalt alloy to both electrode surfaces of the thermistor element assembly through welding and heating glass and welding glass to a front end section including the element assembly and welding sections. CONSTITUTION:The tip sections of leads 5a, 5b plated with nickel 6a, 6b and made up of an iron, nickel and cobalt alloy are connected to each of both electrode 2a, 2b surfaces of a thermistor element assembly 1 through parallel welding. Glass 4 is heated and welded at a front end section containing the thermistor element assembly 1 and the welding sections of the leads 5a, 5b. Accordingly, heat resistance at 400 deg.C or higher can be acquired continuously, and connection by the stable welding of the electrodes formed to the thermistor element assembly and the leads can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention 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 about law.

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 body with electrodes 21L and 2b formed on opposing surfaces, a dumet wire 31L, and sb as the double-sided electrode 21L,
After connecting to 2b from the same direction.

The dumet lead wire 31L was obtained by a manufacturing method in which the entire portion except for a part of the wire ab was hermetically sealed by melting the glass 4.

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

(1) Because the lead wire uses a dumet wire with a copper layer, if it is left at a high temperature exceeding 250"C for a long time, the copper layer of the dumet wire will oxidize and the lead will be sealed in glass. The problem progressed to the inside of the wire, eventually leading to glass cracks and device deterioration and damage.

(2) Since there is an insulating layer of cuprous oxide on the surface of the dumet wire, the method of connecting and reading the thermistor body and the dumet wire is to weld after removing the cuprous oxide layer of the dumet wire. Alternatively, methods using conductive paints have been used, but these methods require complicated manufacturing processes and cannot be manufactured at low cost.

The present invention solves this problem.

The object of the present invention is to provide a glass-encapsulated thermistor that has a continuous residual heat of 400'C or more and allows easy welding of lead wires to the thermistor body.

Means for Solving the Problem In order to solve this problem, the method for manufacturing a glass-encapsulated thermistor of the present invention is to apply nickel plating to each of the two pole faces of the thermistor body, which has electrodes formed on both opposing faces. After connecting the tips of lead wires made of iron, nickel, and cobalt alloys by welding, glass is heated and welded to the thermistor body and the tips of the lead wires, including the welded portions, thereby forming the thermistor body. It is designed to be hermetically sealed.

action According to this configuration, the lead wires contain iron without copper.

By using a nickel-cobalt alloy, continuous heat resistance of over 400°C can be achieved, and by nickel plating the lead wire.

This eliminates the formation of iron oxide film on the lead wire when welding the electrode formed on the thermistor body and the lead wire.
A stable welded connection can be obtained.

Therefore, the present invention can provide a glass-encapsulated thermistor that has continuous heat resistance of 40° C. or more, and that allows easy welding and connection of the lead wire to the thermistor body. .

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

FIG. 1 is a sectional view showing an embodiment of a glass-encapsulated thermistor obtained by the manufacturing method of the present invention, and the same parts as in the conventional example are given the same numbers. In FIG. 1, lead wires made of iron and nickel-cobalt alloy with nickel plating 6a and eb applied to both sides of the thermistor body 1, which has electrodes 1i2a and 2b formed on opposing surfaces, respectively. , sb were connected by parallel welding, and then glass 4 was heat-welded to the tips of the thermistor body 1 and the lead wires sa and sb made of iron, nickel, and cobalt alloy, including the welded portions.

In this way, the glass-encapsulated thermistor shown in FIG. 1 was manufactured.

As described above, according to this embodiment, by using an iron, nickel-cobalt alloy that does not contain copper for the lead wire, it is possible to obtain a continuous heat resistance of 400'C or more. By applying nickel plating, it is possible to obtain a stable welded connection between the electrode formed on the thermistor body and the lead wire.

Note that the temperature of the glass-encapsulated thermistor according to this example is 400°C.
In the high-temperature storage test, no deterioration of the lead wire or a change in resistance value of more than 2.5% was observed even after 1000 hours. Furthermore, the change in resistance value of the thermistor chip due to parallel welding was less than 20%.

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

(1) By using an iron, nickel, and cobalt alloy that does not contain copper for the lead wire, a continuous heat resistance of 400'C or more can be obtained.

t2) By applying nickel plating to the lead wire, an iron oxide film will not be formed on the lead wire when welding the electrode formed on the thermistor body to the lead wire, making it possible to obtain a stable welded connection. can.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a glass-encapsulated thermistor obtained by the manufacturing method of the present invention, and FIG. 2 is a cross-sectional view showing a conventional glass-encapsulated thermistor. 1...Thermistor element, 21L, 2b...
ti, 4...Glass 5a, 5b...Iron
Nickel-cobalt alloy wire, ea, eb...nickel plated.

Claims (1)

[Claims] After connecting the tips of lead wires made of nickel-plated iron, nickel, and cobalt alloy to both electrode surfaces of the thermistor body, which has electrodes formed on opposing surfaces, by welding, the thermistor body and the A method for manufacturing a glass-encapsulated thermistor, in which the thermistor body is hermetically sealed by heat-welding glass to the tip of the lead wire, including the welded part.