JP2001230103A - Glass-sealed thermistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a glass-sealed thermistor which is used as a temperature sensor and enhanced in stability of characteristics and quality by a method wherein the thermistor is restrained from varying in electrical properties due to the influence of an ambient atmosphere when it is sealed in glass. SOLUTION: A laminated chip thermistor element 10 equipped with one or more pairs of inner electrodes 12a and 12b and terminal electrodes 13a and 13b connected to the inner electrodes 12a and 12b is used as a thermistor element, the thermistor element 10 is inserted into a glass tube 14, and then the glass tube 14 is sealed, by which the influence of the ambient atmosphere on the thermistor element 10 can be lessened when it is sealed in glass, so that a glass-sealed thermistor stable in electric properties and quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass-filled thermistor mainly used in a temperature range of 150.degree. C. to 300.degree. C. as a temperature sensor suitable for controlling the temperature of cooking equipment and automobile equipment.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a conventional glass-filled thermistor.

As shown in FIG. 3, a conventional glass-filled thermistor has a thermistor element 2 inserted into a glass tube 1 and a sealed electrode 3 having lead wires 4a and 4b.
a, 3b were inserted into both ends of the glass tube 1 and heated in a neutral gas such as nitrogen or argon to seal the glass tube 1 and the sealing electrodes 3a, 3b.

The thermistor element 2 has terminal electrodes 6a, 6b on both surfaces of a thermistor element 5 which is a thin plate-shaped ceramic mainly composed of an oxide of a transition metal such as Mn, Co, Ni or the like.
Is formed. The terminal electrodes 6a and 6b are generally formed by baking a paste containing Ag as a main component.

Generally, a dumet wire is used as the sealing electrodes 3a and 3b. The dumet wire is formed by coating a surface of a wire made of an Fe—Ni alloy with a Cu intermediate layer and further adding Cu _2.
Borax (Na ₂ B ₄ O ₇ ) is baked on the O layer or Cu ₂ O layer. Terminal electrodes 6a, 6b and sealing electrode 3
a and 3b are electrically connected by contact. The lead wires 4a and 4b are formed by coating a Cu intermediate layer on the surface of a wire made of an Fe—Ni alloy. If the upper limit of the operating temperature of the thermistor is 125 ° C. or less, solder plating is applied.
If the temperature exceeds 5 ° C., nickel plating is applied.

[0006]

However, in the conventional glass encapsulated thermistor, in the glass encapsulating process for manufacturing the same, nitrogen or argon or the like is used in order to prevent oxidation of the dumet wire used as the encapsulated electrodes 3a and 3b. This is performed in a neutral gas atmosphere. However, the encapsulated thermistor body 5 is a ceramic containing a transition metal oxide as a main component, is reduced under the influence of the atmosphere at the time of encapsulation, and changes in electrical characteristics such as a resistance value and a B constant.
There has been a problem that it is difficult to obtain desired characteristics.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a glass-enclosed thermistor having stable characteristics and quality by suppressing changes and variations in electrical characteristics due to the influence of the atmosphere when glass is enclosed. It is assumed that.

[0008]

In order to achieve the above object, the present invention uses a chip-type laminated thermistor element having at least one pair of internal electrodes and a terminal electrode connected to the internal electrode as a thermistor element. And the above glass tube is sealed.

As a result, the influence of the atmosphere at the time of sealing can be reduced, and a glass-filled thermistor having stable characteristics and quality can be obtained.

[0010]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, a chip type thermistor element having at least one pair of internal electrodes and terminal electrodes connected to the internal electrodes is inserted into a glass tube, and a lead wire is inserted. The glass tube is sealed by mounting at both ends of the glass tube so as to electrically connect the encapsulating electrode having a terminal electrode of the chip-type laminated thermistor element to the glass tube. By using a chip-type multilayer thermistor element with terminal electrodes connected to the internal electrodes, the resistance of the thermistor element is not the surface but the resistance generated between the internal electrodes, so it depends on the influence of the atmosphere when glass is sealed. It has an effect that a change in electrical characteristics can be suppressed.

According to a second aspect of the present invention, there is provided a chip-type multilayer thermistor element having at least one pair of internal electrodes and a terminal electrode connected to the internal electrode, wherein the terminal electrode has an encapsulated electrode having a lead wire. 2. The glass cap is sealed by electrically connecting a pair of wires so as to be substantially parallel, and inserting the chip-type laminated thermistor element and the encapsulating electrode into a glass cap. 3. In addition to the effect of suppressing the change in electrical characteristics due to the influence of the atmosphere when glass is sealed, the lead wire mounting structure is made radial, and detected as a temperature sensor as a finished product. The tip of the portion can be reduced in size, and thus has an effect of providing a shape according to the application such as a method of mounting on an electric circuit and a mounting structure.

Further, the invention described in claim 3 is the first invention.
Alternatively, the terminal electrodes of the chip-type multilayer thermistor element of No. 2 are formed by a baked electrode containing copper as a main component, and the terminal electrodes are formed in the same nitrogen atmosphere as when glass is sealed. Changes in electrical characteristics before and after encapsulation can be further suppressed, and since the terminal electrode and the encapsulation electrode are made of the same metal, the contact resistance between the terminal electrode and the encapsulation electrode is small, and changes in electrical characteristics due to the effects of glass encapsulation are extremely small It has the effect that it can be made smaller.

According to a fourth aspect of the present invention, the glass of the first or second aspect is made of a glass containing lead, which can lower the softening point of the glass. This has the effect of lowering the temperature and therefore suppressing changes in electrical properties due to the effects of glass encapsulation.

According to a fifth aspect of the present invention, the sealing electrode according to the first or second aspect is a dumet, whereby the sealing electrode becomes more compatible with glass, so that the airtightness in the glass is improved. It has the effect of suppressing changes in electrical characteristics as a finished product after encapsulation and maintaining quality.

(Embodiment 1) Hereinafter, a glass-filled thermistor according to Embodiment 1 of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a glass-enclosed thermistor according to Embodiment 1 of the present invention.

In the figure, reference numeral 10 denotes a chip-type laminated thermistor element having internal electrodes 12a and 12b inside a ceramic thermistor element 11,
a and 12b connected to terminal electrodes 13a and 13b.

The chip-type laminated thermistor element 10 is inserted into a glass tube 14, and sealed electrodes 15 a, 15 b having lead wires 16 a, 16 b from both ends of the glass tube 14.
Is inserted, and the glass tube 14 is sealed with the terminal electrodes 13a, 13b of the chip-type laminated thermistor element 10 and the sealing electrodes 15a, 15b in contact with each other,
The chip type thermistor element 10 is placed in the glass tube 14.
Is enclosed.

As the sealing electrodes 15a and 15b having the lead wires 16a and 16b, Dumet wires were used. Dumet has Cu on the surface of a wire rod made of an Fe-Ni alloy.
The intermediate layer is coated, and borax (Na ₂ B ₄ O ₇ ) is baked on the Cu ₂ O layer or the Cu ₂ O layer.

The lead wires 16a and 16b are made of Fe--Ni.
The surface of a wire made of an alloy was coated with a Cu intermediate layer. When the upper limit of the operating temperature of the thermistor was 125 ° C. or less, solder plating was applied, and when it exceeded 125 ° C., nickel plating was applied.

The resistance R of the chip type thermistor element 10
Is represented by the following equation.

1 / R = 1 / R1 + 1 / R2 R1 is a resistance generated between the internal electrodes 12a and 12b, and R2 is a resistor between the internal electrodes 12a and 12b and the terminal electrodes 13a and 13b (internal). It is a combined parallel resistance of the resistance generated between the electrode 12a and the terminal electrode 13b, the resistance generated between the internal electrode 12b and the terminal electrode 13a), and the resistance generated between the terminal electrodes 13a and 13b.

However, the chip type thermistor element 10
In, since R2 is extremely large compared to R1,
The resistance R is substantially equal to the resistance R1 between the internal electrodes 12a and 12b.

On the other hand, in the chip-type laminated thermistor element 10, the surface of the thermistor body 11 is liable to change its resistance value under the influence of the atmosphere when the glass is sealed. Hard to receive,
The change in the resistance R1 between the internal electrodes 12a and 12b is extremely small. Therefore, a glass-filled thermistor having a stable characteristic and quality can be obtained as a finished product with almost no influence when glass is filled.

A method of manufacturing the glass-filled thermistor configured as described above will be described.

First, Mn ₃ O ₄ , Co ₃ O ₄ ,
Fe ₂ O ₃ , NiO, Al ₂ O ₃ were prepared by changing the ratio of each metal element to Mn:
Co: Fe: Ni: Al = 36: 30: 20: 10: 4
(At%), mixed for 16 hours in a ball mill using zirconia balls of 10 mmφ as a medium, and dried. This mixed and dried powder is placed in an alumina crucible and calcined at 800 ° C. 10mm calcined powder
18 in a ball mill using zirconia balls of φ
Crush and dry for hours.

Add butyl acetate, dibutyl phthalate and polyvinyl butyral to the pulverized and dried powder, and add
In a ball mill using zirconia balls as a medium for 48 hours. A green sheet having a thickness of 30 μm was prepared from the mixed slurry by a doctor blade method.

Next, after laminating and pressing the green sheets, internal electrodes are formed by screen printing using an electrode paste containing Pd as a main component. Laminate green sheets,
The operation of printing the internal electrodes by crimping is repeated to form one or more corresponding internal electrodes. A green sheet was laminated thereon and pressed to form a laminate block.

After that, the prepared laminated body block was
It is cut to a size of × 0.6 mm to obtain a green chip of a laminate.

Next, after firing the obtained green chip at 1200 ° C. in the air to produce a sintered body, the sintered body is chamfered, and the internal electrodes are completely exposed on both end surfaces of the sintered body. Let it.

Subsequently, Cu was applied to both end faces and side faces of the sintered body.
Was applied in a nitrogen atmosphere at 800 ° C. to form terminal electrodes, thereby producing a chip-type laminated thermistor element.

Finally, the chip-type laminated thermistor element prepared above is inserted into a lead-containing glass tube, and sealed electrodes made of dumet wires having lead wires are inserted into both ends of the glass tube. At 650 ° C
Then, the glass tube and the sealed electrode were sealed to complete a glass-sealed thermistor as shown in FIG.

The characteristics of the glass-enclosed thermistor according to the first embodiment of the present invention obtained above are the same as those of a conventional glass-enclosed thermistor as shown in FIG. 3 manufactured using the same ceramic material as above. The results are shown in Table 1 in comparison.

[0034]

[Table 1]

The results shown in Table 1 are obtained by measuring the resistance values of the thermistor element before glass sealing and the glass-filled thermistor after glass sealing by immersing them in oil baths at 25 ° C. and 85 ° C., respectively. The characteristics before and after and the rate of change in characteristics are obtained.

In the table, R25 is the resistance at 25 ° C., and B25 / 85 is the resistance R25 at 25 ° C.
And a value calculated from the resistance value R85 at 85 ° C.
5/85 = 1n (R25 / R85) / (1 / 298.1)
5-1 / 358.15).

As shown in Table 1, the conventional glass-filled thermistor of the comparative example was affected by the atmosphere at the time of glass-filling, and the rate of change in characteristics before and after the sealing was large, resulting in large variations in characteristics. . On the other hand, in the glass-filled thermistor according to the first embodiment of the present invention, since the influence of the atmosphere at the time of glass filling is suppressed, the rate of change in characteristics before and after filling is small, and the variation in characteristics is small.

(Embodiment 2) Hereinafter, a glass-filled thermistor according to Embodiment 2 of the present invention will be described with reference to the drawings.

FIG. 2 is a sectional view of a glass-enclosed thermistor according to Embodiment 2 of the present invention. The same components as those described in the second embodiment and the first embodiment with reference to FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

FIG. 2 differs from FIG. 1 of the first embodiment in the mounting structure of the lead wire and the shape of the sealing glass.
a, 13b and the encapsulating electrodes 15a, 15b having the leads 16a, 16b are electrically connected so that the leads 16a, 16b are substantially parallel to each other, and the chip type thermistor element 10 and the encapsulating electrodes 15a, 15b are connected. Are inserted into the glass cap 20 to seal the glass cap 20, and the chip-type laminated thermistor element 10 is sealed in the glass cap 20.

The terminal electrodes 13a and 13b and the sealing electrode 15
The electrical connection with a and 15b was made by a resistance welding method or a method of baking and bonding with a conductive paste.

With the structure as in the second embodiment, it is possible to suppress a change in electrical characteristics due to the influence of the atmosphere at the time of enclosing the glass, and a radial lead type glass different from FIG. 1 of the first embodiment. An encapsulated thermistor can be obtained, and the tip of the detection portion can be miniaturized as a temperature sensor as a finished product. Therefore, it is possible to provide a shape according to the application such as a method of mounting on an electric circuit and a mounting structure.

[0043]

As described above, the present invention uses a chip-type laminated thermistor element having one or more pairs of internal electrodes and terminal electrodes connected to the internal electrodes as a thermistor element, and inserts the same into a glass tube. , It is possible to suppress the characteristic fluctuation of the thermistor due to the influence of the atmosphere at the time of enclosing the glass, and therefore, it is possible to produce a high-precision glass-enclosed thermistor at a high yield. is there.

[Brief description of the drawings]

FIG. 1 is a sectional view of a glass-enclosed thermistor according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view of a glass-enclosed thermistor according to Embodiment 2 of the present invention.

FIG. 3 is a cross-sectional view of a conventional glass-filled thermistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Chip-type laminated thermistor element 11 Thermistor body 12a, 12b Internal electrode 13a, 13b Terminal electrode 14 Glass tube 15a, 15b Enclosing electrode 16a, 16b Lead wire 20 Glass cap

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kotaro Suzuki 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. DC10

Claims (5)

[Claims] 1. A chip-type multilayer thermistor element having at least one pair of internal electrodes and a terminal electrode connected to the internal electrode is inserted into a glass tube, and an encapsulated electrode having a lead wire is connected to a terminal electrode of the chip-type multilayer thermistor element. A glass-enclosed thermistor mounted on both ends of the glass tube so as to be electrically connected to the glass tube and sealing the glass tube. 2. A chip-type laminated thermistor element having at least one pair of internal electrodes and a terminal electrode connected to the internal electrodes, wherein the pair of lead wires is substantially parallel to an encapsulated electrode having a lead wire at the terminal electrode. A glass-encapsulated thermistor in which the chip-type laminated thermistor element and the encapsulation electrode are inserted into a glass cap and the glass cap is sealed. 3. The glass-enclosed thermistor according to claim 1, wherein the terminal electrodes of the chip-type laminated thermistor element are formed by baked electrodes containing copper as a main component. 4. The glass-filled thermistor according to claim 1, wherein the glass tube or the glass cap is made of glass containing lead. 5. The glass encapsulated thermistor according to claim 1, wherein the encapsulated electrode is Dumet.