JPH01136304A - Thermistor element - Google Patents

Abstract

PURPOSE:To make ordinary use under high temperature possible and eliminate the deterioration with time, by making a thermistor chip contain carbide, nitride etc., and forming electrode layers with a single metal selected from among tungsten, molybdenum etc., or with an alloy containing one or more of these metals. CONSTITUTION:A thermistor element 1 has a pair of electrode layers 33, 35 on a thermistor chip 2, lead bodies 43, 45 connected to these electrode layers and are sealed with glass 5. The thermistor chip 2 contains one or more of carbide, nitride, boride, and silicide, and when it contains silicon carbide, its content should be equal to or less than 50wt.%. In addition, the electrode layers 33, 35 are formed with a single metal selected from among tungsten, molybdenum and titanium etc., or with an alloy which contains one or more out of these metals. Besides, the second electrode layers are formed on these electrode layers.

Description

[Detailed description of the invention] ■ Background of the invention Technical field The present invention relates to a thermistor element for high temperatures.

Prior art and its problems A thermistor element is a temperature sensor that utilizes the temperature dependence of the electrical resistance of a temperature-sensitive resistor, and is widely used for temperature measurement and temperature control. Particularly for high temperature applications, it is used, for example, in automobile exhaust gas temperature detection sensors, oil and gas combustion control sensors, etc.

Such thermistor elements include glass-sealed thermistor elements, thin film thermistor elements, and the like. Among these, the structure of the glass-sealed thermistor element is such that a pair of electrodes is formed on the thermistor chip, a lead wire is connected to the electrode, and this is sealed in glass.

As a thermistor chip of such a glass-sealed thermistor element, an oxide having a firing temperature of around 1300° C., such as a Mn-Ni-C0 composite oxide, is conventionally used.
Therefore, when glass sealing is performed in the manufacture of a thermistor element, if the glass sealing temperature exceeds 800° C., the electrical resistance value of the thermistor material will fluctuate greatly, causing variations and making control difficult.

Furthermore, in an atmosphere with little oxygen such as an inert atmosphere, the upper limit of the glass sealing temperature is further limited.

For this reason, the upper limit of the working temperature for glass sealing is limited, and accordingly the upper limit of the glass transition temperature of the glass used is also limited, and only sealing glasses with a glass transition temperature of 450°C or lower can be used. Conventional glass-sealed thermistor elements are limited to a normal operating temperature of 450° C. or lower.

Furthermore, in order to prevent the lead wires and electrodes from being oxidized during sealing, noble metals such as gold, platinum, and palladium must be used for the lead wires and electrodes, resulting in extremely high raw material costs. Put it away.

In addition, Dumet wires are used to make lead wires cheaper, but when sealing the glass, they are exposed to temperatures of about 800°C in the atmosphere for several minutes and oxidize, so pickling, Ni
A treatment process such as plating is required.

To address these problems, Japanese Patent Publication No. 42-19061 discloses a thermistor made of silicon carbide single crystal;
In Japanese Patent No. 107498, many thermistors containing silicon carbide as a main component, such as thermistors made of polycrystalline silicon carbide, are proposed.

However, in this case, the carbon-silicon sintered body foams when sealed with glass, the thermistor chip has poor adhesion to the electrode material and the sealing glass, and high-temperature stability is insufficient.

Furthermore, when a thermistor chip electrode is formed by the thick film method, firing is performed at approximately 800 to 900°C during metallization, which may damage the thermistor chip element and cause characteristic deterioration.

In addition, sputtering and vapor deposition methods have low productivity because the film is formed in a vacuum system, and it is difficult to obtain a sufficient film thickness of 5 μm or more, especially about 20 μm. lead to deterioration.

Furthermore, in the thick film method and the vapor phase method, the adhesion to the lead body etc. is insufficient.

In addition, in the thick film method, when glass frit is added to the thick film electrode paste, silicon carbide foams during metallization, resulting in poor appearance and deterioration of properties.

II. OBJECTS OF THE INVENTION The object of the present invention is to provide a thermistor element that can be used regularly at high temperatures, especially at 450° C. or higher, has good characteristics, does not deteriorate over time, has good productivity, and is low cost. It is in.

III Disclosure of the invention Such objects are achieved by the invention described below.

That is, the present invention provides a thermistor element having a pair of electrode layers on a thermistor chip, a lead body connected to the electrode layers, and sealed in glass, in which the thermistor chip is made of carbide, nitride, boride, or If it contains one or more of silicides, and silicon carbide, the content is 50 wt% or less, and the electrode layer contains tungsten, molybdenum, titanium, nickel, tantalum, niobium, iron. , gold, silver, platinum, and palladium, or an alloy containing one or more of these.

Further, a second invention is a thermistor element having a pair of electrode layers on a thermistor chip, a lead body connected to the electrode layers, and sealed in glass, in which the thermistor chip is made of carbide or nitride. When the electrode layer contains one or more of oxides and silicides and also contains silicon carbide, the content thereof is 50 wt% or less, and the electrode layer
It is formed from an elemental metal selected from tungsten, molybdenum, titanium, nickel, tantalum, niobium, iron, gold, silver, platinum, and palladium, or an alloy containing one or more of these, and an electrode layer is further formed on this electrode layer. This thermistor element is characterized in that a second layer is formed.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

FIG. 1 shows an embodiment of the invention.

The thermistor element 1 shown in FIG. 1 has a pair of electrode layers 33 and 35 on the thermistor chip 2.
3.35 are connected to lead bodies 43.45, which are further sealed with glass 5.

The thermistor element 1 of the present invention includes, as the thermistor chip 2, one or more of carbides, nitrides, borides, and silicides, and if silicon carbide is included, the content thereof is 50 wt% or less. Further, the electrode layers 33 and 35 are formed from a single metal selected from tungsten, molybdenum, titanium, nickel, tantalum, niobium, iron, gold, silver, platinum, and palladium, or an alloy containing one or more of these. be done. Further, in the second invention, a second electrode layer (
(not shown) is formed.

Thermistor chip 2 used in thermistor element 1 of the present invention
The thermistor material is not particularly limited, but preferably has a coefficient of thermal expansion of 30 x 10-7 to 90 x 10-? d e
g-1, more preferably 50 x 10-7 to 70 x
10-'de g-'.

Thermal expansion coefficient is 30X10-? deg-' or less than 90
X 10-? When exceeding d e g-1, the electrode layer 33.3
This is because problems such as poor adhesion with 5 occur.

Further, the thermistor element of the present invention preferably contains one or more of carbides, nitrides, borides, and silicides.

Preferred carbides include SiC, B, and C.

Tic, ZrC, Mo, C% NbC1Cr3C2
etc., and BN as a nitrogen compound.

T iN % N b N , Cr 2 N, etc., and
Borides and soybeans include CrB, ZrB, MoB, WB, etc.
Furthermore, as silicides, MoSi, CrSi
, 2, Ti Si2, WS i2, etc.

In such a case, if silicon carbide is included, its content is 50 wt% or less.

This is because if the silicon carbide content exceeds 50 wt%, silicon carbide foams during glass ridge formation, resulting in poor adhesion and connectivity.

By containing one or more of these carbides, nitrogen substances, borides, and silicides, more favorable results can be obtained in terms of stabilization of the B constant in a high temperature range. It is also advantageous in terms of high-temperature sealing in an inert gas.

Such materials include A1□ 03-5iC series, A
l2O3BJC system, A I , O, -3i C-B4C system, AlzO5B
Examples include those containing AI and O, such as JCBN type, Al2O3 (TiN%NbN) type, AI, 03-CrB type, and A1203-TiSi2 type. When A 1203 is included, its content is preferably 50 to 95 wt%.

Note that when SIC is included, the content is preferably 50 wt% or less. This is because as the amount of SiC increases, more foaming occurs during glass sealing.

Among these, the following are particularly preferred in terms of firing temperature, coefficient of thermal expansion, B constant, controllability of electrical resistance, etc.

That is, the thermistor material is composed of a sintered body containing aluminum oxide, silicon carbide, and/or boron carbide, and further, the contents of aluminum oxide, silicon carbide, and boron carbide are respectively xwt% in order at x+y+z=100wt%. %, 7wt%, and zwt%, the compositions Cx5y, z) of aluminum oxide, silicon carbide, and boron carbide are A (100,0,O), B in the ternary composition diagram, as shown in Figure 2. (0,0,100
), C(50,50,O), and is in a composition range that does not include points A and B.

In this case, preferably D (95,0,5), E (5,0,95), C(5
0,50,O), the composition range surrounded by F (95,5,O)1. More preferably D (95,0,5)
,a (50,0,50),C(50,50,O),F
(95,5,O), particularly preferably D (95,0,5), H(80,0,20)
, 1 (65,35,O)1. Favorable results are obtained with the composition range bounded by F (95,5,0).

This composition range is defined as A (
100, O, O) point, i.e. aluminum oxide 100
wt%, the resistance becomes high even at high temperatures, and B (0,0,
100) point, that is, 100t% of boron carbide, it becomes difficult to form a sintered body, and below the BC line, the B constant when used as a thermistor element increases, making it difficult to form a sintered body. This is because it would be difficult to do so. Furthermore, foaming occurs frequently during glass sealing.

When it becomes below the DF line, B4C and/or Si
As a result of adding C, a desired resistance value can be obtained, and when the resistance value is equal to or higher than the EC line, sinterability improves, and a good thermistor chip can be obtained.

Then, it became above the GC line and Aj! z Os amount is 50
When the content is greater than wt%, the sinterability becomes even better.

In such a case, one of the effects of adding 84C and/or SiC is to lower the resistance of Al1zOs.

The effect of this resistance reduction is expressed within the region surrounded by DGCF, and within this region B4C and/or Si
As the amount of C increases, the resistance value gradually decreases. However, G
When the line C is exceeded, the resistance change is saturated and the resistance value hardly decreases.

Therefore, in the region surrounded by the GEC, it can normally be used as a thermistor, but depending on the raw material used, the resistance value may be too low to be used as a thermistor. Therefore, it is particularly preferable that the resistance value be equal to or higher than the GC line because it is not restricted by the raw materials and the resistance value can be controlled to a desired value by adjusting the amount added.

To be more specific, the raw material SiC contains free C and St, as well as 0, Af and 1% Fe.

Although Ti and the like are contained, the SiC content is about 99 tons or more, and it can be used within the area surrounded by GCE. However, if the purity is less than the above range, the resistance value becomes small below the GC line. In addition, the raw material B4C contains O, N, Fe, etc. as impurities, but the purity is 99%.
If it is about wt% or more, it has a saturation resistance value of 10'Ωam or more and can be used within the area surrounded by GEC, but if it is less than the above purity, the resistance value becomes small below the GC line. .

Note that the area surrounded by this DHIF is more preferably J (90, 0.10), K (85, 0, 15), L
(80,20,O), M (70,30,O)
In the region surrounded by , even more preferable resistance values can be obtained.

Aluminum oxide in the sintered body has the chemical formula Aft20
3, and its average grain size is usually in the range of 0.1 to 10μ. Aluminum oxide may deviate from the stoichiometric composition to some extent.

Silicon carbide in the sintered body has the chemical formula SiC, and its average grain size is usually 0.1 to 1.
It is within a range of 1577m.

Silicon carbide may deviate somewhat from its stoichiometric composition.

Boron carbide in the sintered body is represented by the chemical formula 84C, and its average particle size is usually 0.1 to 15J.
It is in the range of ffl.

Boron carbide may deviate somewhat from its stoichiometric composition.

In the sintered body of the present invention, a part of silicon carbide or boron carbide is converted into oxides (silicon oxide, boron oxide) during firing.
It may change to

Such a sintered body can be obtained as follows.

A predetermined amount of aluminum oxide powder and silicon carbide powder and/or boron carbide powder are wet-mixed using a ball mill or the like with the addition of a solvent such as ethanol or acetone.

The aluminum oxide (Aft*Os) powder generally has an average particle size of 0.1 to 5 μm and a purity of 99.5 wt% or more.

Silicon carbide (SiC) powder generally has an average particle size of 0.
5 to 5μ and usually has a purity of 98 wt% or more.

Boron carbide (Ba C) powder generally has an average particle size of 0.
．． A material with a purity of 97 wt% or more is used.

The amount of solvent is approximately 100 to 120 wt% of the powder.

Further, a dispersant or the like may be further added as necessary.

Thereafter, the above mixture is pressure-molded at room temperature, and then sintered under pressure or hot press in an oxygen atmosphere or a non-oxidizing atmosphere.
The compact is obtained by sintering the compact by a HP) sintering method, a hot isostatic pressing (HIP) method, or the like, and then allowing it to cool.

The pressure during pressure molding is 500-2000Kg/cnf
That's about it.

The non-oxidizing atmosphere during sintering may be an inert gas such as N, Ar, He, etc., H%CO, various hydrocarbons, a mixed atmosphere thereof, or a vacuum.

In the case of pressureless sintering, atmospheric pressure is sufficient, and the temperature during sintering is 16
Effective at a temperature of 00 to 1900°C, preferably 1750 to 1800°C.

If the temperature is lower than 1600°C, it will not be sufficiently densified even if sintered for a long time, and if the temperature is higher than 1900°C, the Aut
This is because the interaction between os and SiC and/or B4C becomes intense.

Sintering time is usually 0.5 to 2 hours, especially 175
Preferably, the heating time is about 1 hour at 0°C.

In the case of HP sintering method, the press pressure is 150-250Kg/
For example, the temperature is 150.0~1800℃, especially 1650~1
750°C is preferred.

If the temperature is lower than 1500°C, a dense sintered body cannot be obtained, and if the temperature is higher than 1800°C, Aj! 2
This is because the interaction between os and SiC and/or B4C becomes intense.

Sintering time is generally 1 to 3 hours.

In the case of the HIP sintering method, a compact of raw material powder is pre-sintered in an oxygen atmosphere or a non-oxidizing atmosphere (for example, in a vacuum up to 1200°C, and then preferably in an Ar atmosphere), and then in a HIP furnace. This preliminary sintered body is sintered.

The temperature of pre-sintering is 1400-1650℃, the time is 1
It is best to set it to 3 hours.

In addition, the temperature in the HIP method is 1300 to 1500°C,
Sintering time is 1-5 hours, pressure is 1000-1500
Kg/cnf, and may be carried out in an oxygen atmosphere or an inert atmosphere such as Ar.

In this case, at room temperature, oxygen gas, Ar gas, etc.
Pressure is applied to 0 kg/ba, and then pressure is applied by heating as described above.

The thermistor material produced in this way has a coefficient of thermal expansion of 5.
The resistance value is about 0x10-'~80x10-A/℃, and the resistance value is about 102~107Ωcm at SOO℃, and the resistance value is about 400~107Ωcm at SOO℃.
Even when used or stored in a temperature range of 800°C, there was almost no change in resistance value.

Moreover, the value of B was also 1000 to 5000 at 50 to 480°C.

The Al1203-S i C-B4C type thermistor material like Kono is described in detail in Japanese Patent Application No. 62-61996.

The thermistor material produced as described above is applied as the thermistor chip 2 to the thermistor element 1 of the present invention.

The dimensions of such a thermistor chip 2 are usually 0 vertically.
．． 5-i, omm, width 0.5-1.0mm, thickness 0.
It is about 5 to 1.0 mm.

The electrode layers 33 and 35 of the thermistor element 1 of the present invention are made of a single metal selected from tungsten, molybdenum, titanium, nickel, tantalum, niobium, iron, gold, silver, platinum, and palladium, or one or more of these. It is an alloy containing When using single metals, especially titanium, nickel, tungsten, molybdenum, tantalum, niobium,
It is preferable to use iron, and in this case, it is better in terms of adhesion to the thermistor chip.

get better results.

Further, in the present invention, an alloy containing one or more of these types is also suitably used. The alloys used in this case are Fe-Ni, Fe
It is preferable to use a material containing 50% or more of the above-mentioned metals such as -Ni-Co based metals.

Moreover, the effects of the present invention are exhibited only when the electrode layer is formed with such a composition.

In the present invention, the electrode layer having such a composition is preferably formed by a vapor phase or liquid phase growth method, which has the effect of minimizing changes in the electrical resistance of the thermistor material. is demonstrated.

Methods for forming the electrode layer using such a vapor phase or liquid phase growth film include electrolytic plating, electroless plating, vapor deposition,
Although any conventionally known methods such as sputtering and ion blasting are possible, it is preferable to form by vapor deposition for reasons such as productivity and homogenization of the thin film.

In the present invention, when forming the electrode layer by vapor deposition, the vapor deposition method may be a conventionally known method. In addition, when forming the second electrode layer, if the surface of the electrode layer is degreased and cleaned with a weak acid etc. after forming the electrode layer, when forming the second layer,
More favorable results can be obtained in terms of adhesiveness, ohmic properties, etc.

The thickness of such an electrode layer is usually 0.05 to 5 μm, more preferably 0.3 to 2.0 μm.

If it is less than 0.05 μm, the present invention has no effect, and if it is less than 5 μm
This is because if it exceeds m, problems will arise in terms of productivity and price.

In the second aspect of the present invention, such an electrode layer 31.35
A second electrode layer is formed thereon.

At this time, more favorable results are obtained in terms of wettability with the sealing glass and the lead body.

As the second electrode layer of the present invention, any electrode layer used in ordinary thermistor elements can be used, but in terms of thermal expansion coefficient, reliability at high temperatures, adhesiveness with the electrode layer, etc. It is preferable to use the following.

<1> Vapor-phase growth film of simple metal or alloy.

Although there are no particular restrictions on the membrane material, gold, platinum, palladium alone or alloys containing one or more of these are particularly preferred.

When these materials are used, more favorable results can be obtained in terms of reliability, productivity, etc., especially at high temperatures.

In addition, when using alloys of gold, silver, platinum, and palladium,
Gold, silver, platinum, and palladium are preferably contained in an amount of 50% or more of the entire alloy.

The second electrode layer having such a composition is preferably formed by a vapor phase growth film, and particularly preferably formed by vapor deposition.

The method for forming the second electrode layer having such a composition by vapor deposition may be any conventionally known method. For example, the operating pressure may be approximately txto-3 to lXl0-'Pa.

Moreover, the thickness of the second electrode layer 332.352 in such a case is usually 0.05 to 5 μm, preferably 0.3 to 2.0 μm.

If it is less than 0.05 μm, the present invention has no effect, and if it is less than 5 μm
This is because if it exceeds m, problems will arise in terms of productivity and price.

<2> Plating film The plating film material preferably contains one or more of gold, platinum, palladium, or nickel, particularly gold, platinum, or palladium.

When these materials are used, more favorable results can be obtained in terms of reliability, cost, etc., especially at high temperatures.

The plating methods include electrolytic plating, electroless plating, etc.
Although any conventionally known method can be used, it is preferable to use electrolytic plating in terms of purity and adhesion.

When electrolytic plating is used, various known electrolytic bath compositions, electrodes, electrolytic vessels, working temperatures, etc. may be used. In addition, the current density is 0, 5~2, OA/
It may be approximately dm''.

Each of the above metals is usually contained alone, but in some cases, the tm or two or more thereof may be contained in a total amount of 50 wt% or more.

Further, the thickness of the second electrode layer in such a case is usually 0.
The thickness is 5 to 5 μm, preferably 2 to 3 μm.

The present invention has no effect with a 0.5 μm end groove;
This is because problems will arise in terms of productivity and price if the amount is exceeded.

3> Metal foil The metal foil material is preferably nickel, iron, tungsten, titanium, molybdenum, or gold alone, or an alloy containing 1 fj or more of these.

When these materials are used, more favorable results can be obtained in terms of reliability, especially at high temperatures.

In this case, the metal foil is preferably one containing nickel and iron, and the alloy containing nickel and iron is Ni2O~80wt%, Fe40~
80 wt% is preferred. These have 20w
Cobalt, manganese, etc. may be contained within a range of t% or less.

Among these, in terms of thermal expansion coefficient, 29wt%N
It is preferable to use a Kovar alloy having a composition of i-17wt% Co-remaining Fe and a 42 alloy having a composition of 41 to 43wt% Ni-remaining Fe.

Further, as the metal foil, tungsten, molybdenum, titanium, or gold is also preferable, but these may be a single metal or an alloy containing 50 wt % or more of one or more of these.

As a method for forming the second electrode layer using such metal foil, any conventionally known method can be used, such as brazing using gold, platinum, palladium, copper, etc. All you have to do is In this case, the method of brazing,
The conditions may be a conventionally known method such as pressure bonding in a vacuum at a brazing temperature of 1000 to 1200°C.

In addition, the thickness of the second electrode layer in such a case is usually 5 to 5.
200 μm, preferably 20 to 50 μm.

This is because if the thickness is less than 5 μm, productivity is poor, and if it exceeds 50 μm, problems arise in terms of cost and shape.

<4> Thermal Sprayed Film The thermal sprayed film material is preferably an alloy containing nickel and iron, or molybdenum, tungsten, or an alloy thereof.

When these materials are used, more favorable results can be obtained in terms of reliability, productivity, etc., especially at high temperatures.

As alloys containing nickel and iron, the above-mentioned 3>
It is preferable to use those detailed in .

In this case, molybdenum, tungsten, or an alloy containing molybdenum and/or tungsten is also preferably used. In the case of an alloy, it is preferable that molybdenum and/or tungsten be contained in an amount of 50 wt% or more.

With compositions other than these, the above-mentioned effects will not be achieved.

For thermal spraying, various methods using gas flame, electric arc, plasma, etc. as a heat source are possible, but among these, plasma spraying is particularly preferred from the viewpoint of adhesion and control of film thickness.

Plasma spraying is a surface processing technology that utilizes the high thermal energy of thermal plasma to melt a powder material and spray it onto the surface of a base material to form a coating. It is possible to obtain a film with good adhesion on a material (300°C) at a high processing speed, and it is also easy to produce a composite film.

A typical plasma spraying method involves sustaining an arc between a water-cooled anode and a cathode using a high-frequency starter and a DC power supply, and heating the plasma gas supplied thereto to an ultra-high temperature to generate a plasma jet. As the plasma jet generation gas, gases such as Ar, He, H, N2, and mixed gases are used.

When a powder spray material is supplied into this plasma jet, the spray material is heated and melted, accelerated, collides with the surface of the base material, absorbs heat while getting wet with the material, and solidifies to form a film.

In this case, the plasma gas flow rate is usually 1 to 100 JI/m.
The substrate temperature is about 100 to 300°C, the plasma jet temperature is about too much to 30,000°C, and the raw material particle diameter is about 10 to 60 μm.

The thickness of the electrode layer 33.35 formed in this way is
The thickness is usually 5 to 100 μm, more preferably 20 to 50 μm. , less than 5 μm is disadvantageous in terms of productivity;
If it is 0 μm or more, it is meaningless.

As the lead wires 43 and 45 as lead bodies used in the thermistor element 1 of the present invention, any conventionally known lead wires can be used, but from the viewpoint of thermal expansion coefficient, cost, etc., the above-mentioned Kovar alloy or 4270I alloy can be used. It is preferable to use

Such a lead wire has a film thickness on its surface.

If it is coated with a heat-resistant film such as Ni plating with a thickness of about 0.1 to 2.0 μm, even more favorable results can be obtained in terms of oxidation prevention and heat resistance during glass sealing.

Such lead wires usually have a diameter of 0.2 to 0.5 mm,
The length is approximately 20 to 100 mm.

As a method for connecting such lead wires to the electrode layer,
Various methods are possible, such as a method of electrically contacting and connecting using a heat-resistant conductive material paste such as gold paste, a method using spot welding, and a method using an ultrasonic bonder.

When using a heat-resistant conductive paste, it is preferable to use a glass fritless paste that contains conductive particles, a solvent, and, if necessary, a binder, and does not contain glass. This is because if a glass frit-containing product is used, foaming may occur during connection, resulting in poor connectivity.
This is because the adhesion deteriorates.

FIG. 1 shows an example using conductive paste 53,55. In addition, spot welding methods include passing a current to the fusion temperature for a sufficient period of time to weld the lead wires, or placing the entire thermistor element in a furnace to bring it to the fusion temperature. Any known method may be used.

The method of spot welding is described in detail in Japanese Patent Publication No. 19061/1983. Further, as the ultrasonic bonder, a conventionally known method may be used.

Since the thermistor element of the present invention can be used at high temperatures, the glass 5 used has a glass transition temperature of 550 to 800°C, more preferably 600 to 750°C.
, is good.

The composition of the glass 5 used is not particularly limited as long as the glass transition temperature is within the above range, but it is preferable to use borosilicate glass or aluminoborosilicate glass.

When using borosilicate glass, its composition is 5i0
2 content is 40 to 96 wt%, B20. The content of
~20 wt% is preferred.

Further, when using aluminoborosilicate glass, it is preferable that the above composition contains 30 wt% or less of Al 203.

Both of these cause a decrease in insulation resistance at high temperatures, so N
It is preferable that the alkali components such as a and ni are 1 wt% or less.

Such sealing glass 5 is a glass tube with a diameter of about 1.5 to 2.5 mm and a length of about 5 mm. The thermistor chip with electrode layers on both sides and lead wires connected to it is inserted into this glass tube, and heated to about 850 to 1000°C in an inert atmosphere such as argon gas as shown in Figure 1. Seal it like this.

An example of a method for manufacturing such a thermistor element will be briefly described below.

For example, it contains carbide or nitride and has a coefficient of thermal expansion of 30.
X 10-7~90 X 1 o-? A square with a diameter of about 3 inches and a thickness of about 0.5 mm is prepared. On both sides of this electrode layer, a single metal selected from tungsten, molybdenum, titanium, nickel, tantalum, niobium, iron, gold, silver, platinum, and palladium, or an alloy containing one or more of these, is applied in a vacuum, for example. Formed by vapor deposition.

Preferably, the second electrode layer is formed on such an electrode layer using the various compositions and methods described above.

The thus formed squares are cut into squares of about 0.75 mm on each side using a dicing saw or the like to form chips.

The chips thus obtained had diameters of 0, 2 to 0.
, 5 mm, length 2. A lead wire of about 0 to 100 mm, preferably a lead wire made of Kovar alloy or 42 alloy alloy, is connected using the method described above.

Insert such a chip into a glass tube with a diameter of about 1.5 to 2.5 mm and a length of about 5 mm, preferably made of borosilicate glass or aluminoborosilicate glass.
It may be sealed in an inert atmosphere such as an Ar gas atmosphere at a temperature of about 50 to 1000°C.

Thereafter, if necessary, 21-ging is performed at 500 to 750°C for about 10 to 100 hours.

■Specific effects of the invention The thermistor element of the present invention contains one or more of carbides, nitrides, borides, and silicides as the thermistor chip 2, and when silicon carbide is included, the content is equal to the content. is 50 wt% or less, and furthermore, the electrode layer 33.35 is made of an elemental metal selected from tungsten, molybdenum, titanium, nickel, tantalum, niobium, iron, gold, silver, platinum, and palladium, or one of these. Formed from an alloy containing one or more types. Moreover, in the second invention, a second electrode layer is further formed on such an electrode layer.

Therefore, in the present invention, it is possible to bake the thermistor chip at a high temperature when forming it, and therefore, a glass with a high glass transition temperature can be used as the sealing glass, and constant use at high temperatures is possible.

In addition, since the glass sealing process can be performed in an inert atmosphere such as an Ar gas atmosphere, there is no oxidation of electrode layers or lead wires during manufacturing, and there is no need for post-processing, which significantly reduces manufacturing costs. can be reduced.

In addition, the electrode layer is made of tungsten, tributene, titanium,
Since it is made from a single metal selected from nickel, tantalum, niobium, iron, gold, silver, platinum, and palladium, or an alloy containing one or more of these, the raw material cost is significantly lower than that of conventional products. Diagnosis can be reduced.

In addition, in the second invention, the electrode layer has a multilayer structure and has a predetermined composition, so it has good adhesion with the thermistor material, has excellent high temperature stability, and furthermore, it is easy to select the electrode material. It is.

Furthermore, since the thermal expansion coefficients of the thermistor chip, electrode layer, and sealing glass are approximately equal, there is no fear that the sealing glass will crack even when used at high temperatures, and stable performance is exhibited.

(2) Specific Examples of the Invention Hereinafter, the present invention will be explained in more detail by giving specific examples of the invention.

<Example> A diameter of 3 inches and a thickness of 0.5 mm having the composition shown in Table 1.
A composite sintered body of mm was produced by hot press sintering under the conditions shown in Table 1.

The coefficient of thermal expansion of this material is shown in Table 1.

Electrode layers were formed on both sides of the composite sintered body thus obtained by vapor deposition. The composition and thickness of the electrode layer are shown in Table 1.

The operating pressure for vapor deposition was 3 x 10-'Pa.

In addition, some of the ones shown in Table 1 have a second electrode layer.
formed a layer. The film thickness, composition, and formation method are shown in Table 1.

In this case, when thermal spraying is used, the plasma gas Ar and the gas flow rate are 5 to 20 j! /min, substrate temperature 20
The conditions were 0 to 300°C and a sprayed particle size of 5 to 20 μm.

The R, , x of each sprayed film was approximately 30 μm. Moreover, the metal foil was palladium-brazed at 1100°C.
Furthermore, the plating current density was set to IA/dm'.

The wafer thus obtained was sliced into 0.75 mm on each side using a diamond blade using a peripheral slicing machine.
The thermistor chip was obtained by cutting it into a square shape.

Such a thermistor chip has a diameter of 0.3 mm and a length of 6
5 mm leads and wires were connected using glass fritless gold paste. Lead wire material purchases are shown in Table 1.

The thus obtained product was inserted into borosilicate glass having a diameter of 2.5 mm and a length of 4 mm, and the glass was sealed at 850° C. in an Ar gas atmosphere. After this is subjected to aging treatment, a thermistor element 1 as shown in FIG.
Various types were prepared.

The following characteristics were investigated for these products.

(1) Changes in resistance value were measured at the initial stage of resistance change and after storage at 500° C. for 5000 hours.

For evaluation, the change in resistance value is ΔR1, and the initial resistance value is Ro: (ΔR/Ro) X 1 0 0
(%).

(2) Ohmic property Deterioration of ohmic property was investigated by measuring current and voltage values at the initial stage and after storage at 500° C. for 5,000 hours. The evaluation criteria are as follows.

0 ------- No deterioration.

×・・・・・・Deteriorated.

The results are shown in Table 1.

Further, for samples No. 28 and No. 28, FIG. 3 shows changes in ohmic properties after storage at SOO° C. for 5000 hours.

In addition, in sample No. 25, foaming occurred during glass sealing, and the resistance value decreased by 15% or more.

From these results, the effects of the present invention are clear.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention. FIG. 2 is a ternary diagram showing a preferred composition of the thermistor material used in the present invention. FIG. 3 is a graph for explaining the present invention in detail. Explanation of symbols 1...Thermistor element 2...Thermistor chip 33.35...Electrode layer 43.45...Lead body 5...Glass. fGl FIG, 2 SiC(Y) FIG, 3 1 (10-7R) Procedure Neho Sekisho (spontaneous) February 16, 1989 1, Indication of the case 1989 Patent Application No. 294798 2, Title of the invention Thermistor element 3, relationship to the case of the person making the amendment Patent applicant name TDT-K Co., Ltd. 4, agent address 2!839, 3rd floor, Tenjin Yasaka Kosan Building, 3-23-1 Yushima, Bunkyo-ku, Tokyo 113 Japan 0367 Fax, 839-0327 Name (8286) Patent attorney Akira Ishii ・
) Each section of the "Detailed Description of the Invention" and Drawing 6, contents of the amendment ■) The claims of the specification are amended as shown in the attached sheet. 2) Delete the statement "Moreover..." in lines 10 to 14 of page 4 of the specification. 3) From page 5, line 6 to line 11 of page 6, “
However, it is to provide ~. However, in this case, the silicon carbide sintered body foams when sealed with glass, resulting in poor adhesion of the thermistor chip to the electrode material and sealing glass, and poor high-temperature stability. In addition, in the thick film method, when glass frit is added to the thick film electrode paste, silicon carbide foams during metallization, resulting in poor appearance and deterioration of properties. have developed A as a thermistor material which does not have the above-mentioned drawbacks and has less foaming due to the presence of glass.
A material based on li Os -B4 C-3tC has been proposed (Japanese Patent Application No. 62-61996). However, in the case of a thermistor chip containing such carbides, if the thermistor chip electrode is formed using the thick film method, the thermistor chip element will be damaged due to firing at a temperature of about 800 to 900°C during metallization.
Characteristics may deteriorate. ■ Purpose of the Invention The purpose of the present invention is to provide a material that can be used regularly at high temperatures of 450°C or higher, that does not cause foaming due to glass content, and that has good properties.
The purpose is to provide a thermistor element that does not deteriorate over time and has high productivity (and low cost). 4) Replace "boride" in line 13 of page 7 with "boride." Correct to "monster". 5) On the 9th page, in the 4th line, after "It will be done."
contains one or more of carbides, nitrides, borides, and silicides. ” is inserted. 6) "The present invention" in the 5th line of the 9th page is amended to "also the present invention". 7) In the 6th line of the 9th page, "for thermistor material" is corrected to "if the thermistor material is the one mentioned above." 8) This is the r item on the 9th page, 9th line. " is corrected to "It is preferable that it is a thing." 9) On page 9, lines 14 to 16, “Also...
··preferable. ” to be deleted. 10) Correct "ridge" on the 7th line of page 10 to "seal". 11) Delete "It is preferable" in the 4th line of page 11. 12) Correct rNJ on the 9th line of the 17th page to "N2". 13) Correct rHJ on the 10th line of the 17th page to "H2". 14) rdeg- “7℃” on the 8th line of page 19
Correct to "hot". 15) Correct rBJ on the 13th line of the 1st 9th page to "B constant". 16) “332°352” on page 24, line 10
Delete. 17) In the 16th line of page 24, "The material is gold, platinum, or the like" is amended to "There is no particular restriction on the material, but in particular, gold or platinum." 18) In the first line of page 26, "tojiwa" is amended to "there are no particular restrictions on closing, but in particular." 19) Correct "etc." in the 10th line of page 27 to "etc.". 20) In the 18th line of page 27, amend "as" to "there is no particular restriction on as, but especially." 21) "Contains" in the 11th line of page 28 is corrected to "contains". 22) Delete "I will not do these..." in the 13th to 14th lines of the 28th page. 23) Correct "Material" in the 4th line and 16th line of the same page 29 to "Base material" respectively. 24) “Substrate” on page 29, line 19 of the same page is “base material”
Correct to. 25) Correct "raw material" in the first line of page 30 to "thermal spray material". 26) Correct "conductive material" in the first line of page 31 to "conductive". 27) Correct "method by" in the third line of page 31 to "method by". 28) Add a line break to "Also" on page 31, line 13 of the specification. 29) Correct "between time" to "time" in the 14th to 15th lines of the 31st page. 30) In the 19th line of page 31, add a line break to "Also." 31) Correct "etc." in the fourth line of page 33 to "r etc.". 32) In the 9th line of page 33, "carbide or nitride" is amended to "one or more of carbides, nitrides, borides, and silicides." 33) Correct rrVJ on the 17th line of the 34th page to rVJ. 34) Correct "silicide" in the first line of page 35 to "of silicide." 35) Delete "What is the content?" in the second line of page 35. 36) Delete "Furthermore, ... is possible." from the 20th line of the 35th page to the 6th line of the 36th page. 37) rV as described in rVJ on page 36, line 16
Correct to IJ. 38) Between the 13th line and the 14th line of page 38, there is a statement that states, ``Additionally, various elements shown in Table 1 were fabricated as comparative examples. Insert the following statement. 39) Table 1 (Part 1), Table 1 (Part 2), and Table 1 (Part 1) on pages 40, 41, and 42 of the same
Replace 3) with separate sheets. 40) Replace Figure 3 of the drawing with a separate sheet. 2. Claims (1) A thermistor element having a pair of electrode layers on a thermistor chip, a lead body connected to the electrode layers, and sealed in glass, wherein the thermistor chip is made of carbide, nitride, Contains one or more of borides and silicides, and if silicon carbide is included, the content is 50%
wt% or less, and the electrode layer contains tungsten, molybdenum, titanium, nickel, tantalum, niobium,
A thermistor element characterized in that it is formed from a single metal selected from iron, gold, silver, platinum, and palladium, or an alloy containing one or more of these. (2) In a thermistor element having a pair of electrode layers on a thermistor chip, a lead body connected to the electrode layer, and sealed in glass, the thermistor chip is made of one of carbides, nitrides, diborides, and silicides. If it contains one or more of the following, and also contains silicon carbide, the content is 50w
t% or less, and the electrode layer is made of tungsten,
A second electrode layer is formed on this electrode layer from an elemental metal selected from molybdenum, titanium, nickel, tantalum, niobium, iron, gold, silver, platinum, and palladium, or an alloy containing one or more of these. A thermistor element characterized in that a layer is formed.

Claims (2)

[Claims] (1) A thermistor element having a pair of electrode layers on a thermistor chip, a lead body connected to the electrode layer, and sealed in glass, in which the thermistor chip is made of carbide, nitride, boride, or silicide. If it contains one or more of these, and also contains silicon carbide, the content must be 50
wt% or less, and the electrode layer contains tungsten, molybdenum, titanium, nickel, tantalum, niobium,
A thermistor element characterized in that it is formed from a single metal selected from iron, gold, silver, platinum, and palladium, or an alloy containing one or more of these. (2) In a thermistor element which has a pair of electrode layers on a thermistor chip, a lead body is connected to this electrode layer, and is sealed in glass, the thermistor chip is made of carbide, nitride, boride and silicide. If it contains one or more of these and also contains silicon carbide, the content must be 50w.
t% or less, and the electrode layer is made of tungsten,
A second electrode layer is formed on this electrode layer from an elemental metal selected from molybdenum, titanium, nickel, tantalum, niobium, iron, gold, silver, platinum, and palladium, or an alloy containing one or more of these. A thermistor element characterized in that a layer is formed.