JPS6146002A - Glass sealed thermistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

Structure of conventional examples and their problems Among conventional glass-encapsulated thermistors, those that require particularly high heat resistance use borosilicate glass as the glass material, IJ-1''
MK Kovar wire (an alloy of iron, nickel, and cobalt) is used, and its heat resistance limit is about 500°C. However, with this configuration, during glass encapsulation and high temperature storage tests,
There was a problem that the thermistor element, which is the encapsulated object, deteriorated, that is, the resistance value increased rapidly (usually 10 to 100 times), and stable production and stable performance could not be maintained.

Purpose of the Invention The present invention has been made in view of the above points, and aims to prevent deterioration of the thermistor element, which is an encapsulated object, during glass encapsulation and high temperature storage tests, and to maintain stable production and stable performance. Structure of the Invention The glass-encapsulated thermistor of the present invention is designed to provide a glass-encapsulated thermistor in which the electrode surfaces on both sides of the thermistor element are held from both sides by lead wires that do not contain bolts, and the entire structure is assembled as described above. It is hermetically sealed with a glass material that has a coefficient of thermal expansion similar to that of the lead wire.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIGS. 1 and 2 are a cross-sectional view and a side view of a glass-encapsulated thermistor according to the present invention, in which a thermistor element 1 having a flat or disc shape with platinum electrodes formed on both sides is connected to a cobalt-free lead wire 3 ( For example, the lead wire 3 is held from both sides with 42 Ni--Fe), and the entire lead wire 3 except for a part is hermetically sealed with a high heat-resistant glass tube 2 (for example, borosilicate glass). At this time, the difference in thermal expansion coefficient between the lead wire 3 and the glass tube 2 should be within ±10%.

Next, the change in resistance value during glass encapsulation will be explained with reference to Table 1 below showing the resistance change rate before and after encapsulation. The lead wire 3 and the thermistor element 1 are connected in the glass tube 2.
When sealing and sealing, a high temperature of approximately SOO°C is required.

Therefore, in the case of the conventional example, 2 s Nt-1e-Co-
Cobalt in the Fe lead wire is thermistor element 1
As a result, the resistance value of the thermistor element 1 increases rapidly (by 63 times in the example). On the other hand, in the case of the present invention, the above problem does not occur because the lead wire 3 is made of, for example, 42Ni-Fe and does not contain cobalt.

Table 1 Next, regarding the change in resistance value during the high temperature storage test, 500
This will be explained with reference to Table 2 below, which shows the resistance change rate before and after a high temperature storage test at 1000 hours at 100°C. As in the case of the change in resistance value before and after the encapsulation, conventionally t7) 29 N i
In the case of a lead wire made of -16Co-Fe, the resistance value of the thermistor element 1 increases 21 times before and after the high-temperature storage test, whereas in the case of the present invention, for example, a lead wire that does not contain cobalt and is made of 42Ni-Fe. 3, the resistance value of the thermistor element 1 before and after the high temperature storage test is extremely small, 1.04 times.

Table 2 Note that the lead wire 3 of the present invention is of course not limited to a cobalt-free lead wire made of 42Ni-Fe.

Effects of the Invention (1) Since the glass-encapsulated thermistor of the present invention uses lead wires that do not contain cobalt, there is no sudden increase in resistance value during glass encapsulation and high-temperature storage tests, resulting in stable production and stable performance. It is possible to maintain

(11) Since it does not contain cobalt, which is expensive as a material, it can be provided at an extremely low cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a glass-encapsulated thermistor according to the present invention, and FIG. 2 is a side view of the same. 1...Thermistor element, 2...-Glass material (glass tube), 3... Lead wire. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure f Figure 2

Claims (1)

[Claims] A glass-encapsulated thermistor having a structure in which the electrode surfaces on both sides of the thermistor element are held from both sides by lead wires that do not contain cobalt, and the whole is hermetically sealed with a glass material having a coefficient of thermal expansion similar to that of the lead wires.