JP2001118706A - Paste, film, and parts of negative temperature coefficient thermistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide negative temperature coefficient thermistor paste which can be sintered at a relatively low temperature of 1,000 deg.C and can form a negative temperature coefficient thermistor film having a small specific resistance when the paste is sintered. SOLUTION: Negative temperature coefficient thermistor paste contains negative temperature coefficient thermistor crystal power composed of an La-Co oxide having a perovskite crystal structure, the powder of lead or lead-bismuth borosilicate glass, an organic vehicle, and an organometallic compound which is soluble in the organic vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative characteristic thermistor paste, a negative characteristic thermistor film and a negative characteristic thermistor component having a negative resistance-temperature characteristic, that is, a negative characteristic. It is possible to apply a thick film forming technique such as a screen printing method, sinter at a relatively low temperature of 1000 ° C. or less, and form a negative characteristic thermistor film having a good thermistor characteristic at a low specific resistance value. And a negative-characteristic thermistor film and a negative-characteristic thermistor component formed using such a negative-characteristic thermistor paste.

[0002]

2. Description of the Related Art The negative resistance-temperature characteristic of a negative characteristic thermistor material is widely applied in fields such as temperature measurement and temperature compensation. Examples of such a negative-characteristic thermistor material include a La-Co-based oxide having a perovskite-type crystal structure and Mn-Co-Ni- having a spinel-type crystal structure.
Cu-based oxides are known.

[0003] When a negative characteristic thermistor component such as a temperature measuring element or a temperature compensating element is to be constituted by using these negative characteristic thermistor materials, one method is La-Co.
Negative characteristic thermistor crystal powder composed of a base oxide or a Mn—Co—Ni—Cu base oxide is formed into an arbitrary shape, and then, at a high temperature of 1300 ° C. or more so as to cause solid diffusion in the formed body. There is a method of obtaining a bulk sintered body by firing.

[0004] As another method, there is a method in which a paste containing a negative characteristic thermistor material is prepared, and this paste is applied on an appropriate substrate and baked to obtain a negative characteristic thermistor film. In this case, the paste contains, in addition to the negative-characteristic thermistor material, an organic vehicle and a low-softening-point lead borosilicate glass or an alkali-added glass that serves as a sintering aid, and is prepared by dispersing these. Is common.

As described above, the technique of forming a negative characteristic thermistor film or a negative characteristic thermistor component using a paste is a technique that is particularly interesting for the present invention.

[0006]

SUMMARY OF THE INVENTION Mn-Co-Ni-C in which the sintering temperature of the negative characteristic thermistor crystal particles is relatively low.
When a u-based oxide is used, it is possible to obtain a negative-characteristic thermistor film having a specific resistance lowered to some extent by using a negative-characteristic thermistor paste to which lead borosilicate glass is added.

However, when a La—Co-based oxide is used as the thermistor material, the sintering temperature between the negative characteristic thermistor crystal grains is relatively high, and the low softening point glass component serving as an insulating layer is not only used. Due to the viscous flow, electrical contact between the conductive particles is lost, and only a negative-characteristic thermistor film having a high specific resistance is obtained, which has a problem that the original negative thermistor characteristic is greatly impaired.

To solve this problem, there is a method in which metal particles are added to the paste to reduce the resistance value. In this case, however, the dispersion of the dispersibility of the metal particles directly results in the dispersion of the thermistor characteristics. Encounter the problem.

Accordingly, an object of the present invention is to provide a negative characteristic thermistor paste using a La—Co-based oxide so that a low specific resistance and good thermistor characteristics can be obtained. It is an object of the present invention to provide a negative temperature coefficient thermistor film and a negative temperature coefficient thermistor component formed using a characteristic thermistor paste.

Another object of the present invention is to provide Mn-Co-Ni.
A negative characteristic thermistor paste using a Cu-based oxide is intended to further reduce the specific resistance, and a negative characteristic thermistor film and a negative characteristic thermistor component configured using such a negative characteristic thermistor paste are provided. Is to try.

[0011]

A negative characteristic thermistor paste according to a first aspect of the present invention comprises a negative characteristic thermistor crystal powder comprising a La-Co-based oxide having a perovskite type crystal structure, a lead borosilicate glass or Including lead borosilicate bismuth glass powder and an organic vehicle,
In order to solve the above-mentioned technical problem, the present invention is further characterized in that an organic metal compound soluble in an organic vehicle is included.

When the above-mentioned negative characteristic thermistor paste contains lead borosilicate glass, the lead borosilicate glass has a composition of xSiO ₂ -yB ₂ O ₃ -zPbO, and x is 10 to 55 mol%. , Y is preferably in the range of 10 to 20 mol%, and z is preferably in the range of 35 to 70 mol%.

When the above-mentioned negative characteristic thermistor paste contains lead bismuth borosilicate glass, this lead bismuth borosilicate glass is made of iSiO ₂ —
jB ₂ O ₃ -kPbO-mBi ₂ O ₃
Is 12.4 to 17.4 mol%, and j is 18.8 to 26.3.
Mol%, k is 18.8-26.3 mol%, m is 30.0
Preferably, it is in each range of ５50.0 mol%.

In the above-mentioned negative characteristic thermistor paste, the organometallic compound preferably contains Pt.

[0015] The negative characteristic thermistor paste according to the second aspect of the present invention is a Mn-C having a spinel type crystal structure.
It contains a negative characteristic thermistor crystal powder composed of an o-Ni-Cu-based oxide, a glass powder, and an organic vehicle. In order to solve the above-mentioned technical problem, a powder of lead bismuth borosilicate glass is used as the glass powder. It is characterized in that it is used.

In the negative characteristic thermistor paste according to the second aspect, the lead bismuth borosilicate glass is made of iS
iO ₂ -jB ₂ O ₃ has a composition of -kPbO-mBi ₂ O _3, i is from 12.4 to 17.4 mol%, j is 18.8～
It is preferable that 26.3 mol%, k is in the range of 18.8 to 26.3 mol%, and m is in the range of 30.0 to 50.0 mol%.

The present invention is also directed to a negative-characteristic thermistor film formed by applying the above-mentioned negative-characteristic thermistor paste on a substrate and baking the same.

Further, the present invention provides an insulating substrate, the above-described negative characteristic thermistor film formed on the insulating substrate, and an insulating substrate formed on the insulating substrate so as to be connected to one end of the negative characteristic thermistor film. The present invention is also directed to a negative-characteristic thermistor component including one electrode and another electrode formed on an insulating substrate so as to be connected to the other end of the negative-characteristic thermistor film.

[0019]

FIG. 1 is a plan view showing a negative characteristic thermistor component 1 according to an embodiment of the present invention.
FIG.

The negative characteristic thermistor component 1 includes an insulating substrate 2 made of, for example, alumina. On one main surface of the insulating substrate 2, first and second main surface electrodes 3 and 4 are spaced apart from each other. Is formed. These main surface electrodes 3 and 4 are formed by applying and baking a conductive paste containing Ag.

On the insulating substrate 2, the first and second
The negative characteristic thermistor film 5 is formed so as to electrically connect the main surface electrodes 3 and 4 to each other. The negative-characteristic thermistor film 5 is formed by applying the negative-characteristic thermistor paste according to the present invention on the insulating substrate 2 and baking the same.

FIG. 3 is a plan view showing a negative characteristic thermistor component 11 according to another embodiment of the present invention, and FIG.
FIG. 4 is a sectional view taken along line IV-IV in FIG. 3.

The negative characteristic thermistor component 11 shown in FIGS. 3 and 4 is the same as the negative characteristic thermistor component 1 shown in FIGS. 1 and 2, and has an insulating substrate 2, first and second main surface electrodes 3 and 4. And a negative thermistor film 5.

The negative temperature coefficient thermistor component 11 shown in FIGS. 3 and 4 further includes first and second end electrodes 12 and 13 formed on each end of the insulating substrate 2, respectively. First and second end electrodes 12 and 13
Are formed so as to cover each part of the first and second main surface electrodes 3 and 4, respectively, and are electrically connected to the first and second main surface electrodes 3 and 4, respectively. I have.
These end electrodes 12 and 13 are made of, for example, Ag-Pd
Is formed on each end of the insulating substrate 2 by applying a conductive paste containing

The negative characteristic thermistor component 11 further includes a protective film 14 formed so as to cover the negative characteristic thermistor film 5.
It has. The protective film 14 further extends so as to cover the main surface electrodes 3 and 4 and to cover a part of each of the end electrodes 12 and 13. The protective film 14 is made of, for example, glass.

The above-mentioned negative characteristic thermistor parts 1 and 1
The negative characteristic thermistor paste is used to form the negative characteristic thermistor film 5 provided in each of the elements 1 and 2. In the present invention, the negative characteristic thermistor paste containing a La—Co-based oxide as the thermistor material (hereinafter referred to as “first Mn-C
A negative characteristic thermistor paste containing an o-Ni-Cu-based oxide (hereinafter, “second negative characteristic thermistor paste”) may be used.

The first negative characteristic thermistor paste comprises a negative characteristic thermistor crystal powder composed of a La—Co-based oxide having a perovskite crystal structure, a powder of lead borosilicate glass or lead bismuth borosilicate glass, and an organic vehicle. And an organometallic compound soluble in an organic vehicle.

On the other hand, the second negative characteristic thermistor paste has a Mn--Co--Ni--C having a spinel type crystal structure.
It contains a negative characteristic thermistor crystal powder composed of a u-based oxide, a powder of lead bismuth borosilicate glass, and an organic vehicle.

The powder of lead borosilicate glass or lead bismuth borosilicate glass contained in the above-mentioned first negative characteristic thermistor paste, or the powder of lead bismuth borosilicate glass contained in the second negative characteristic thermistor paste, At a relatively low temperature of 1000 ° C. or less,
Enables sintering of negative thermistor paste.

The lead borosilicate glass contained in the first negative characteristic thermistor paste is xSiO ₂ -yB ₂ O ₃ -zPb
O composition, x is 10 to 55 mol%, y is 10 to 2
It is preferred that 0 mol% and z are in the respective ranges of 35 to 70 mol%.

The lead bismuth borosilicate glass contained in the first negative characteristic thermistor paste or the lead bismuth borosilicate glass contained in the second negative characteristic thermistor paste is iSiO ₂ -jB ₂ O ₃ -kPbO-mB.
has a composition of i ₂ O _3, i is from 12.4 to 17.4 mol%, j is from 18.8 to 26.3 mol%, k is from 18.8 to 2
Preferably, 6.3 mol% and m are in the respective ranges of 30.0 to 50.0 mol%.

A preferable range of each composition of the lead borosilicate glass and the lead bismuth borosilicate glass described above is that the specific resistance value of the negative characteristic thermistor film formed using the negative characteristic thermistor paste is 1000 Ω · cm.
It is possible to: If the value falls outside this preferred range, the specific resistance value may exceed 1000 Ω · cm.

The organic vehicle contained in each of the first and second negative characteristic thermistor pastes includes, for example,
What melt | dissolved the ethylcellulose type resin and the alkyd resin in the organic solvent can be used.

With respect to such an organic vehicle, in the first negative characteristic thermistor paste, a negative characteristic thermistor crystal powder composed of La—Co based oxide and lead borosilicate glass or lead bismuth borosilicate glass are used. Powder and
It can be obtained by adding an organic metal compound, mixing, and then performing a dispersion treatment. On the other hand, in the second negative characteristic thermistor paste, Mn-Co-Ni-C
It can be obtained by adding a negative characteristic thermistor crystal powder and a powder of lead bismuth borosilicate glass from a u-based oxide, mixing and then performing a dispersion treatment.

The organometallic compound contained in the first negative characteristic thermistor paste is provided, for example, by a resinate of a specific metal group, and is soluble in an lipophilic organic solvent such as an aromatic or α-terpineol. Therefore, the organometallic compound can be uniformly distributed in the negative characteristic thermistor paste. The organometallic compound precipitates metal particles by thermal decomposition, and such metal particles cause electrical contact between thermistor particles provided by a negative characteristic thermistor crystal powder made of La-Co-based oxide. As described above, since the thermistor particles are interposed in a uniform distribution state, the resistivity of the obtained negative characteristic thermistor film can be reduced, and
Good thermistor characteristics with little variation can be obtained.

As the above-mentioned organometallic compound, for example, a Pt group resinate can be advantageously used.
This Pt-based organometallic compound causes evaporation and thermal decomposition of the solvent in an air atmosphere at 300 to 500 ° C.,
Pt crystals are precipitated.

The amount of the organometallic compound added to the negative characteristic thermistor paste is preferably 3% by weight or less in terms of a metal component. This is because an excessive addition exceeding 3% by weight significantly lowers the thermistor constant exhibiting negative thermistor characteristics.

In the second negative characteristic thermistor paste, the resistance is reduced by controlling the viscosity of the glass. The viscosity of the lead-bismuth borosilicate glass used in the second negative characteristic thermistor paste decreases during temperature rise, and the wetting of the negative characteristic thermistor crystal powder composed of a Mn-Co-Ni-Cu-based oxide is promoted. . Therefore, the resistance can be reduced without impairing the electrical contact between the negative characteristic thermistor crystal powders.

Hereinafter, the present invention will be described with reference to more specific examples.

[0040]

EXAMPLE 1 A first negative characteristic thermistor paste containing negative characteristic thermistor crystal powder composed of La—Co-based oxide was prepared as follows.

The negative characteristic thermistor crystal powder composed of La—Co oxide (LaCoO ₃ ) was 70.6% by weight, the lead borosilicate glass powder was 7.8% by weight, and the organic Pt compound (Pt content: 12%) was used. 0.5% by weight) and 2.0% by weight,
These were mixed so that the organic vehicle contained 19.6% by weight, and dispersed by a roll mill to prepare a negative characteristic thermistor paste.

Here, the mixing ratio of the organic Pt compound is 3% by weight in the residual solid ratio (the ratio in the fired film composition composed of La—Co-based oxide, glass and Pt crystal).
It is made to become.

As the lead borosilicate glass added as described above, those having four types of glass compositions as shown in Samples 1 to 4 in Table 1 were used. Samples 1 to 4 were made of xSiO ₂ -yB ₂ O ₃ -zPbO
X is 10 to 55 mol% and y is 10 to 2
0 mol% and z are changed within the respective ranges of 35 to 70 mol%.

[0044]

[Table 1]

Next, a substrate made of alumina having a purity of 96% by weight was prepared, and the above-mentioned negative characteristic thermistor paste for each sample was screen-printed thereon, and was heated at 950 ° C. for 1 hour in air. By firing, a negative thermistor film was formed, and the thermistor characteristics of the negative thermistor film were evaluated.

Here, the plane dimension of the negative characteristic thermistor film is 1 mm × 1 mm as in the case of evaluation of a general resistor.
Using an Ag electrode, in a temperature range of 25 to 100 ° C. in air, measure the sheet resistance value of the negative characteristic thermistor film, multiply the sheet resistance value by the film thickness to obtain the film specific resistance value, The thermistor constant was determined. Table 1 shows these film resistivity values and thermistor constants.

As can be seen from Table 1, Samples 1 to 4 had a film specific resistance of 403 to 497 Ω · cm, and 2
A thermistor constant of 423 to 2613 K is obtained, and as described above, the film specific resistance can be reduced by adding an organic Pt compound.

In the first embodiment, the first negative characteristic thermistor paste containing a La—Co-based oxide was used.
Although lead borosilicate glass was used as a glass component, it has been confirmed that substantially the same results can be obtained by using lead borosilicate bismuth glass as a glass component.

[0049]

Example 2 A second negative characteristic thermistor paste containing a Mn-Co-Ni-Cu-based oxide was prepared as follows.

Mn-Co-Ni-Cu-based oxide (Mn
72. A negative characteristic thermistor crystal powder comprising _1.52 Ni _0.72 Co _0.93 O ₄ and 3.6 mol% of CuO added thereto.
7. 0% by weight of powder of lead borosilicate bismuth glass.
These were mixed so that 0% by weight and 20.0% by weight of the organic vehicle were contained, and subjected to a dispersion treatment using a roll mill, thereby producing a negative characteristic thermistor paste.

Here, as the lead bismuth borosilicate glass, one having several glass compositions as shown in Table 2 was used. In Table 2, Samples 5 to 7 are iSiO ₂
In the composition of _{-jB 2 O 3 -kPbO-mBi 2} O 3, i to 12.4 to 17.4 mol%, the j 18.8 to 2
6.3 mol%, k is 18.8 to 26.3 mol%, m is 3
It has been changed within the range of 0.0 to 50.0 mol%.

[0052]

[Table 2]

With respect to the negative characteristic thermistor paste of each sample described above, a negative characteristic thermistor film was formed in the same manner as in Example 1, and the thermistor characteristics of the negative characteristic thermistor film, that is, the film specific resistance and the thermistor constant were determined. evaluated. Table 2 shows the film specific resistance and the thermistor constant.

As can be seen from Table 2, according to Samples 5 to 7, the film specific resistance of 563 to 687 Ω · cm
A thermistor constant of 2-316 K is obtained. According to Example 2, a low film specific resistance value of 1000 Ω · cm or less can be realized without adding an organometallic compound.

[0055]

As described above, according to the negative characteristic thermistor paste according to the present invention, it is possible to form a film by a thick film forming technique, and by firing at a relatively low temperature of 1000 ° C. or less, the negative characteristic thermistor can be formed. A film can be formed, a low specific resistance value can be realized in the formed negative characteristic thermistor film, and a good thermistor characteristic can be obtained in a negative characteristic thermistor component constituted by the negative characteristic thermistor film. Can be given.

[Brief description of the drawings]

FIG. 1 is a plan view showing a negative temperature coefficient thermistor component 1 according to an embodiment of the present invention.

FIG. 2 is a front view of the negative characteristic thermistor component 1 shown in FIG.

FIG. 3 is a plan view showing a negative temperature coefficient thermistor component 11 according to another embodiment of the present invention.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

[Explanation of symbols]

 1,11 Negative characteristic thermistor parts 2 Insulating substrate 3,4 Main surface electrode 5 Negative characteristic thermistor film 12,13 End electrode

Continuation of the front page (72) Inventor Hiroshi Takagi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. (reference) 5E034 BA08 BA09 BB06 BC01 BC04 BC19 DA02 DB04 DC01 DE07

Claims (8)

[Claims] 1. La having a perovskite type crystal structure
A negative characteristic thermistor paste comprising-a negative characteristic thermistor crystal powder composed of a Co-based oxide, a powder of lead borosilicate glass or lead bismuth borosilicate glass, an organic vehicle, and an organic metal compound soluble in the organic vehicle. . 2. The lead borosilicate glass comprises xSiO ₂
-Yb ₂ O ₃ has a composition of -zPbO, x is 10 to 55
Mol%, y is 10 to 20 mol%, z is 35 to 70 mol%
The negative characteristic thermistor paste according to claim 1, wherein 3. The lead-bismuth borosilicate glass according to claim 1, wherein
SiO_Two−jB_TwoO _Three-KPbO-mBi_TwoO_ThreeComposition of
I is 12.4 to 17.4 mol%, and j is 18.8.
２６26.3 mol%, k is 18.8 to 26.3 mol%, m
Is in the range of 30.0 to 50.0 mol%.
2. The negative characteristic thermistor paste according to 1. 4. The negative characteristic thermistor paste according to claim 1, wherein the organometallic compound contains Pt. 5. Mn—Co having a spinel type crystal structure
-A negative-characteristic thermistor paste including a negative-characteristic thermistor crystal powder composed of a Ni-Cu-based oxide, a powder of lead-bismuth borosilicate glass, and an organic vehicle. 6. The lead bismuth borosilicate glass according to claim 1, wherein
SiO_Two−jB_TwoO _Three-KPbO-mBi_TwoO_ThreeComposition of
I is 12.4 to 17.4 mol%, and j is 18.8.
２６26.3 mol%, k is 18.8 to 26.3 mol%, m
Is in the range of 30.0 to 50.0 mol%.
6. The negative characteristic thermistor paste according to 5. 7. A negative-characteristic thermistor film formed by applying the negative-characteristic thermistor paste according to claim 1 on a substrate and firing the paste. 8. The insulating substrate, the negative characteristic thermistor film according to claim 7, formed on the insulating substrate, and formed on the insulating substrate so as to be connected to one end of the negative characteristic thermistor film. A negative electrode thermistor component, comprising: an electrode formed on the insulating substrate so as to be connected to the other end of the negative characteristic thermistor film.