JP4488325B2 - Composition for thermistor, method for producing the same, and thermistor using the composition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermistor, a composition for the thermistor, and a method for manufacturing the thermistor. For example, the present invention relates to a thermistor formed on an insulating substrate, a composition for thermistor, and a method for manufacturing the thermistor.
[0002]
[Prior art]
Examples of the composition of the thick film negative characteristic thermistor (hereinafter abbreviated as NTC thermistor) include metal oxides such as Mn (manganese), Co (cobalt), Fe (iron), and Ni (nickel) having thermistor characteristics. And RuO as a conductive material₂An NTC thermistor composition prepared by mixing (ruthenium oxide) and glass powder, followed by heating and firing is known.
[0003]
FIG. 9 shows an example of an NTC thermistor.
This NTC thermistor is manufactured as follows. First, the first electrode 102 is formed on the insulating substrate 101, and then the NTC thermistor film 103 is formed on the first electrode 102 by using the NTC thermistor composition.
[0004]
Further, a second electrode 104 is formed on the NTC thermistor film 103, and a glass film 105, an outer coating film 106, and the like are formed on the second electrode 104 to form a sandwich-shaped NTC thermistor 100.
[0005]
This sandwich-shaped NTC thermistor 100 can have a lower resistance than a sheet-shaped NTC thermistor in which an NTC thermistor composition is printed between electrodes on the same plane.
[0006]
An example of a method for producing the NTC thermistor composition paste is shown in FIG.
[0007]
First, thermistor characteristics, for example, manganese oxide (Mn_ThreeO_Four), Cobalt oxide (Co_ThreeO_Four), Iron oxide (Fe_ThreeO_Four) And the like are mixed so as to have a predetermined composition, and heated and fired under a predetermined condition to cause a solid-phase reaction to obtain a composite oxide (step S201).
[0008]
Subsequently, this composite oxide is coarsely pulverized using a ball mill (step S202), and then ruthenium oxide (RuO) as a conductive material is used.₂) And glass powder (step S203), and using a mortar, these materials are pulverized and mixed uniformly (step S204).
[0009]
Further, a thickener or a solvent is added to the pulverized and mixed material (step S205), and an NTC thermistor composition paste is obtained (step S206).
[0010]
[Problems to be solved by the invention]
However, the sandwich NTC thermistor has the following problems.
[0011]
That is, when producing a sandwich-shaped NTC thermistor, the Co₂Gas is generated. Further, a metal oxide such as Mn, Co, Fe, Ni having NTC thermistor characteristics causes an oxidation-reduction reaction with Ag or Ag · Pd alloy used as an electrode material, and O₂Gas may be generated.
[0012]
These generated gases remained in the NTC thermistor film 103 and caused defects such as pinholes and voids (voids) 108. When defects such as pinholes and voids (holes) 108 occur in the NTC thermistor film 103, the effective area of the NTC thermistor film 103 decreases, and the electrical characteristics thereof deteriorate.
[0013]
Further, the gas confined inside the NTC thermistor film 103 causes defects such as pinholes and voids (voids) in the thermistor layer during firing, and the first electrode and the second electrode constituting the NTC thermistor 100. The electrode may be short-circuited, and the function of the sandwich NTC thermistor may not be exhibited.
[0014]
FIG. 11 shows a cross section when the sandwich-shaped NTC thermistor 100 manufactured using the above-described manufacturing method is cut, and the interface between the NTC thermistor film 103 and the second electrode 104 is enlarged and observed with a scanning electron microscope. An example of a partial photograph is shown.
[0015]
From FIG. 11, it can be seen that a large number of defects such as pinholes and voids 108 having a diameter of 30 to 40 μm exist in the NTC thermistor film 103. As described above, defects such as pinholes and voids (voids) 108 are caused by gas trapped inside the NTC thermistor film 103 when the sandwich-shaped NTC thermistor 100 is manufactured, such as pinholes and voids (holes). A defect is generated.
[0016]
When such a fatal problem occurs, the manufactured NTC thermistor cannot be used, and thus the product yield at the time of manufacturing is greatly reduced.
[0017]
In addition, if there are defects such as pinholes or voids in the vicinity of the surface of the NTC thermistor, there will be problems such as moisture intruding into the defects such as pinholes and voids when using the NTC thermistor, and reducing the characteristics of the NTC thermistor. Arise.
[0018]
This is because the glass powder used as the raw material for the NTC thermistor composition used when producing the NTC thermistor has a too high softening point, so that defects such as the above-mentioned pinholes and voids (voids) are produced during the production of the NTC thermistor. There is a possibility that the removal of the gas that causes the generation of water is insufficient.
[0019]
The present invention has been made to solve the above-described problems, and its object is to provide a composition for a thermistor capable of suppressing the occurrence of defects inside the thermistor film during the production of the thermistor and a method for producing the same. And providing a thermistor using the composition.
[0020]
[Means for Solving the Problems]
  In order to achieve the above object, the composition for the thermistor of the present invention has the following constitution. That is, a first component obtained by mixing at least two kinds of metal oxides having thermistor characteristics and heating and firing, ruthenium oxide as a conductive substance, and a glass component as an insulator,Consist ofA composition for a thermistor comprising 20 to 50% by weight of the raw material powder of the first component, 1 to 20% by weight of the ruthenium oxide, and 40 to 60% by weight of the glass component. The component consists of a highly softened glass having a glass softening point higher than 700 ° C. and a low softened glass having a glass softening point of 700 ° C. or less. High softened glass: low softened glass = 25-50 wt%: 75-50 wt% It has been prepared to blend.
[0021]
  Also preferably, the aboveHigh softening glassThe raw material powder isThe average particle size is 2 μm, and the raw powder of the low softening glass has an average particle size of 0.5 μm.Has been prepared.
[0025]
Preferably, the first component includes at least two kinds of oxides of Mn, Co, Fe, and Ni.
[0028]
  In order to achieve the above object, a method for producing a thermistor composition of the present invention includes the following steps. That is, a first component obtained by mixing at least two kinds of metal oxides having thermistor characteristics and heating and firing, ruthenium oxide as a conductive substance, and a glass component as an insulator,Consist ofA method for producing a composition for a thermistor, comprising a preparation step for adjusting the glass component, a raw material powder of the first component that is 20 to 50% by weight of the composition, and 1 to 20% by weight of the composition. A mixing step of mixing 40% to 60% by weight of the composition with the ruthenium oxide being 40% to 60% by weight of the composition. In the glass component preparation step, the glass softening point is higher than 700 ° C. The softened glass is crushed into a raw material powder having an average particle diameter of 2 μm, the low softened glass having a glass softening point of 700 ° C. or less is crushed into a raw material powder having an average particle diameter of 0.5 μm, and then a high softened glass: low softening Glass = 25-50% by weight: Mix to 75-50% by weight.
[0029]
  In order to achieve the above object, the thermistor of the present invention has the following configuration. That is, a first electrode formed on one surface of an insulating substrate of a predetermined size, and claims 1 to3Using the composition for a thermistor described in any one of the above, a functional film formed so as to overlap the first electrode, and a second electrode formed so as to overlap the functional film And having.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Below, with reference to drawings, the manufacturing method of the NTC thermistor composition 33 used when manufacturing the NTC thermistor 30 and the NTC thermistor 30 which are suitable embodiment of this invention is demonstrated in detail.
[0031]
The composition ratio and mixing ratio of the composition described in the present embodiment are examples, and unless otherwise specified, the scope of the present invention is not limited to them. Rather, it is determined according to the characteristics and specifications of the NTC thermistor to be manufactured.
[0032]
The structure of the NTC thermistor 30 is the same as that of the NTC thermistor 100 shown in FIG. 9, and the only difference is that the NTC thermistor film 34 is different because the NTC thermistor composition 33 is different.
[0033]
Therefore, an explanatory diagram showing the structure of the NTC thermistor 30 having the NTC thermistor film 34 manufactured using the NTC thermistor composition 33 of the present invention and a description of common parts constituting the NTC thermistor film 34 are omitted here. Only the NTC thermistor composition 33 will be described.
[0034]
[Preparation of NTC thermistor composition paste]
A method for preparing a paste of the NTC thermistor composition 33 will be described below. The ratio of each component of the composition is described using a weight percentage [wt%] unless otherwise specified.
[0035]
An example of a method for producing a paste of the NTC thermistor composition 33 is shown in FIG.
[0036]
First, manganese oxide (Mn) having thermistor characteristics_ThreeO_Four), Cobalt oxide (Co_ThreeO_Four), Iron oxide (Fe_ThreeO_Four), A metal oxide such as nickel oxide (NiO), for example, Mn shown in the formulation 21 of FIG._ThreeO_Four: Co_ThreeO_Four: NiO: Fe_ThreeO_Four= 1: 1: 1: 0.2, or Mn shown in Formulation 11_ThreeO_Four: Co_ThreeO_Four: NiO: Fe_ThreeO_Four= 1: 1: 1: 0.
[0037]
Subsequently, the metal oxide prepared in a predetermined composition is pulverized and mixed, and then the metal oxide is heated and fired in a firing furnace at a predetermined condition, for example, about 1000 ° C. for about 2 hours. A solid oxide is reacted to obtain a composite oxide (step S10).
[0038]
In addition, the compounding ratio of each metal oxide powder should just mix oxides, such as Mn, Co, Fe, and Ni which have thermistor characteristics according to the target characteristic, and the compounding 11 of FIG. Needless to say, it is not limited to 21 and can be changed according to the target characteristics.
[0039]
Subsequently, the composite oxide obtained by the solid phase reaction is pulverized so as to have a particle size of about several to several tens of μm (step S11), and ruthenium oxide (RuO) as a conductive substance is contained in the composite oxide powder.₂) For example, the compounding ratio with the composite oxide shown in FIG. 4, ie, composite oxide: RuO.₂= 49: 1, 45: 5, 40:10, 30:20.
[0040]
Also added RuO₂The amount of NTC thermistor composition 33 (composite oxide + RuO₂+ Compound oxide in glass powder) and RuO₂Are weighed so as to be 60 to 40 wt% shown in FIG. 4 (step S12).
[0041]
Next, as an insulator, for example, two types of lead borosilicate glasses having different glass softening points (hereinafter abbreviated as a high softening point and a low softening point) are made to have a blending ratio shown in FIG. Each glass is weighed so that the total glass amount of the softening point and the low softening point is 40 to 60 wt% as the total glass weight% in the NTC thermistor composition 33, mixed and pulverized, and then the composite oxide and RuO₂(Step S13).
[0042]
Of the two types of lead borosilicate glass glasses, those having a high softening point (softening temperature of 700 ° C. or higher) are those pulverized to have an average particle size of about 2.0 μm, and have low softening. For those having a point (softening temperature of 700 ° C. or lower), those which are finely pulverized until the average particle size becomes smaller than the high softening point so that the average particle size is about 0.5 μm are used.
[0043]
Here, of the two types of lead borosilicate glass glasses, a glass having a low softening point has a smaller average particle size than a glass having a high softening point, and a finer one is used when an NTC thermistor is manufactured. This is because it is easy to permeate through the fine gaps of the powders constituting the NTC thermistor composition.
[0044]
The same effect can be obtained even if the glass powder is prepared so that the sintering rate at the time of heating and firing is different. The sintering rate can be controlled using various methods such as glass composition and particle size.
[0045]
Therefore, it is needless to say that any insulator may be used as long as the insulator is prepared so that the sintering speed is different at the time of heating and firing.
[0046]
In this embodiment, as the glass powder, finely pulverized lead borosilicate glass having a low softening point or two types of lead borosilicate glasses having different softening points and average particle diameters are used. Needless to say, it is not limited to lead borosilicate glass, and the type, average particle size and glass composition of the glass can be changed according to the intended properties.
[0047]
Subsequently, using a ball mill, the above-described composite oxide powder, RuO₂The mixed powder made of glass powder is wet pulverized and mixed to a predetermined particle size using a ball mill (step S14).
[0048]
Here, a zirconia ball having a diameter of about 1 to 10 mm is used as the grinding medium, and the grinding time is several to several tens of hours.
[0049]
Next, a thickener and a solvent are added to the pulverized mixed powder. That is, as an organic vehicle, for example, butyl carbitol containing about 5 to 15 wt% of ethyl cellulose and an organic solvent are added so as to be about 35 wt% of the mixture (step S15).
[0050]
Subsequently, by using three rolls or the like and kneading so that the mixed powder, the thickener, and the solvent are uniformly mixed (step S16), an NTC thermistor paste comprising the NTC thermistor composition 33 is obtained. (Step S17).
[0051]
[Production of NTC thermistor]
Next, a method for manufacturing the NTC thermistor 30 will be described with reference to FIG. The values such as area and thickness shown in the following description are examples, and the present invention is not limited to this, and is determined according to the characteristics and specifications of the thick film thermistor to be manufactured. .
[0052]
First, a conductive paste such as Ag or Ag · Pd alloy is printed on one surface of the insulating substrate 101 made of an alumina substrate or the like (step S90), and then the insulating substrate 101 is baked to a predetermined size. The first electrode 102 is formed (step S91).
[0053]
Subsequently, the above-described paste of the NTC thermistor composition 33 is printed so as to overlap with a part of the first electrode 102 (step S92).
[0054]
Next, the insulating substrate 101 is baked to form an NTC thermistor film 34 having a predetermined size (step S93). The firing is performed, for example, at about 850 ° C. for about 10 minutes, and the thickness of the NTC thermistor film 34 after the firing is, for example, about 40 μm.
[0055]
Subsequently, a conductive paste such as Ag or Ag / Pd alloy is printed so as to partially overlap the NTC thermistor film 34 (step S94), and then the insulating substrate 101 is baked to a predetermined size. The second electrode 104 is formed (step S95). Note that the facing area between the first electrode 102 and the second electrode 104 is, for example, 0.25 mm.²To a degree.
[0056]
Subsequently, the NTC thermistor 30 is obtained by printing the glass 105, baking it, and printing the outer coating film 106 (step S96).
[0057]
[Defects and electrical characteristics of NTC thermistors]
The results of examining the structure and electrical characteristics of the NTC thermistor sample manufactured according to the manufacturing method described above will be described below with reference to FIGS.
[0058]
First, the produced NTC thermistor sample and comparative sample will be described.
[0059]
Two kinds of lead borosilicate glass powders (high softening point 700 ° C. or higher and low softening point 700 ° C. or lower) having different glass softening points were prepared as insulators so that the blending ratio and total glass amount shown in FIG. Furthermore, the composite oxide and RuO prepared for each formulation of FIG.₂Glass powder was added to the mixture to prepare an NTC thermistor composition paste.
[0060]
Next, NTC thermistor samples (samples 401 to 603) shown in FIG. 6 were prepared using these pastes. Moreover, the comparison samples 4-6 were produced as a comparison.
[0061]
Each prepared sample was cut, its cross section was polished, and defects such as pinholes and voids existing in the cross section were observed using a scanning electron microscope, and the diameter and number thereof were measured. Moreover, the sheet resistance value and B constant which are the electrical characteristics of each sample were measured.
[0062]
As an example of the measurement result, the raw material compounding ratio of the composite oxide in the NTC thermistor composition is the compound 21 (Fe_ThreeO_FourFIG. 6 shows the measurement results when 0.2 is used, and FIG._ThreeO_FourFIG. 7 shows the measurement results when 0 is used.
[0063]
Note that the composite oxide and RuO in FIGS.₂4 is 45: 5 in FIG. 4 (compounds 6 to 8), and the composite oxide and RuO are mixed.₂Of the NTC thermistor is 60 to 40 wt%, and the total glass amount is the remaining 40 to 60 wt%.
[0064]
[Defect suppression by low softening point glass]
Next, the defect which generate | occur | produces in the produced NTC thermistor is demonstrated.
[0065]
Taking the samples 501 to 503 having the total glass amount of 50 wt% in FIG. 6 and the comparative sample 5 as an example, the comparative sample 5 produced using the high softening point lead borosilicate glass has a large diameter of about 30 to 40 μm. While many defects are seen (see FIG. 11), the sample 501 using a low softening point glass, or two types of high softening point (average particle size 2 μm) and low softening point (average particle size 0.5 μm) From the samples 501 and 502 using the lead borosilicate glass, large defects of about 30 to 40 μm are not generated at all, and very small defects of about 2 to 4 μm are observed.
[0066]
FIG. 8 shows a cut surface of the sample 502 as an example showing an example of defects generated in the samples 501 to 503, and a large defect of about 30 to 40 μm is completely generated as compared with FIG. Not.
[0067]
From these facts, when producing NTC thermistors, the use of low softening point lead borosilicate glass alone or mixed with high softening point lead borosilicate glass can suppress the occurrence of defects in NTC thermistors. Can do.
[0068]
This is because when a low softening point lead borosilicate glass is used, it becomes liquid from the time when the firing temperature is low at the time of NTC thermistor production, so compared to the high softening point lead borosilicate glass that becomes liquid after the firing temperature becomes high This is because the viscosity of the liquid is low and fluidized easily.
[0069]
Since this low-viscosity liquid easily penetrates into the fine gaps of the raw material powders of the NTC thermistor, defects that tend to occur in the fine gaps between the powders are reduced.
[0070]
In addition, in addition to the above-described effects, when the fine low softening point lead borosilicate glass (average particle size 0.5 μm) is mixed with the high softening point lead borosilicate glass (average particle size 2 μm), Since the effect is also added, the generated defects are further reduced.
[0071]
That is, when the high softening point lead borosilicate glass is softened and fluidized in the high temperature range of the firing temperature, the high softening point lead borosilicate glass starts to penetrate into the gaps between the raw material powders of the NTC thermistor. At this time, the low softening point lead borosilicate glass with low viscosity and high fluidity compared to the high softening point lead borosilicate glass, the high softening point lead borosilicate glass promotes the finer gap between the powders. To penetrate. As a result, defects that are likely to occur in the gap between the powders are reduced.
[0072]
In this embodiment, when the low softening point lead borosilicate glass is used in combination with the high softening point lead borosilicate glass, the average particle size of the low softening point lead borosilicate glass is set to the high softening point lead borosilicate glass. Although it was used after being refined from the average particle size of the glass, it can be liquefied at a lower temperature by refining the low softening point lead borosilicate glass, which increases its fluidity and helps reduce the above-mentioned defects. It is.
[0073]
  The effect described above is as shown in FIG.When using a high softening point glass mixed with a low softening point glass,Sample 50 with 50 wt% glass2Not only 503 but also a sample 40 with a glass amount of 40 wt%2˜403 or sample 60 having a glass amount of 60 wt%2˜603 also shows the same effect.Samples 401, 501, and 601 in FIG. 6 are reference examples.
[0074]
  From this,When using a high softening point glass mixed with a low softening point glass, as shown in FIG.Glass amount is 40 to 60%, high softening point glass in glass: compounding ratio of low softening point glass is25~ 50:75If it is -50, the effect similar to the above is exhibited.
[0075]
  In addition, the low softening point lead borosilicate described aboveTheThe effect when mixed with high softening point lead borosilicate glass is as shown in FIG._ThreeO_FourSample 10 produced using 0.22-103, Sample 202~ 203, sample302~3The same applies to 03.Samples 101, 201, and 301 in FIG. 7 are reference examples.
[0076]
Since these effects are the same as those described with reference to FIG. 6, the description thereof is omitted.
[0077]
[Electrical characteristics of NTC thermistor]
Next, electrical characteristics in the manufactured NTC thermistor will be described.
[0078]
The samples 501 to 503 and the comparative sample 5 having a total glass amount of 50 wt% in FIG. 6 and the samples 201 to 203 and the comparative sample 2 in FIG. 7 are taken as examples.
[0079]
[B constant]
First, the B constant will be described.
[0080]
From FIG. 6, Fe_ThreeO_FourIn the case of NTC thermistor to which 0.2 is added, samples 502 and 503 using a mixture of lead borosilicate glass having a high softening point and a low softening point show the same B constant and 3500 K as those of comparative sample 5. ing.
[0081]
Further, the B constant of the sample 501 using only the low softening point lead borosilicate glass is 3500K, which is the same value as that of the comparative sample 5.
[0082]
On the other hand, Fe shown in FIG._ThreeO_FourIn the case of an NTC thermistor to which is not added, the B constant of samples 201 to 203 using a low softening point lead borosilicate glass alone or mixed with a high softening point lead borosilicate glass is 3550K, The same value as the B constant of the comparative sample 201 using only the softening point lead borosilicate glass is shown.
[0083]
Therefore, in order to suppress defects in the NTC thermistor, a low softening temperature lead borosilicate glass can be used alone or mixed with a high softening temperature lead borosilicate glass as an insulator. The B constant of the NTC thermistor can be controlled to a substantially constant value.
[0084]
[Resistance value]
Next, the resistance value will be described.
[0085]
From FIG. 6, Fe_ThreeO_FourIn the case of NTC thermistor to which 0.2 is added, as shown in Samples 501 to 503, a low softening point lead borosilicate glass: a high softening point lead borosilicate glass is mixed at a high softening point. When the ratio of the lead borosilicate glass increases to 0 to 50 wt%, the resistance value increases to 1600 to 3200 Ω, and the resistance value of Comparative Sample 5 approaches 4800 Ω.
[0086]
From this, according to this embodiment, the same B constant is maintained by changing the blending ratio of low softening point lead borosilicate glass: high softening point lead borosilicate glass while keeping the total glass amount constant. However, NTC thermistors having different resistance values can be produced.
[0087]
On the other hand, Fe shown in FIG._ThreeO_FourThe same tendency can be seen in the case of an NTC thermistor to which no is added.
[0088]
That is, as seen in samples 201 to 203, the ratio of the low softening point lead borosilicate glass to the high softening point lead borosilicate glass is 0 to 50 wt%. It can be seen that the resistance value increases to 1100 to 1700Ω and increases to the resistance value of 3300Ω of the comparative sample 5 as it increases.
[0089]
From this, according to the present embodiment, the same B can be obtained by changing the compounding ratio of the composite oxide and changing the compounding ratio of the low softening point lead borosilicate glass: high softening point lead borosilicate glass. NTC thermistors having different resistance values can be produced while keeping constant.
[0090]
Therefore, the NTC thermistor composition 33 paste is produced by mixing the low softening point lead borosilicate glass alone or with the high softening point lead borosilicate glass, and the NTC thermistor 30 is produced using this paste, thereby producing the NTC thermistor. Since defects do not occur in the film 34, it is possible to prevent a decrease in product yield due to short-circuiting of the first electrode 102 and the second electrode 104 due to these, and life deterioration due to moisture intrusion into the void.
[0091]
Further, since the prepared sample has a B constant comparable to that of the comparative sample, the paste for the NTC thermistor composition 33 can be replaced with a conventional NTC thermistor paste without requiring design changes. .
[0092]
Further, the sheet resistance value obtained can be designed within a certain range by controlling the addition amount of the low softening point glass and the composition of the composite oxide.
[0093]
As described above, according to this embodiment, when producing a composition for a thick film negative characteristic thermistor, a low softening point glass having a predetermined particle size is used alone or a high softening point acid having a predetermined particle size is used. A composition for a thick film negative characteristic thermistor is prepared by using a powder mixed with lead glass so as to have a predetermined mixing ratio, and a thick film negative characteristic thermistor is produced using this composition. Occurrence can be suppressed.
[0094]
In addition, the electrical characteristics of the manufactured thick film negative characteristic thermistor show performance equal to or higher than that of the conventional one. The following effects can be obtained by the thick film negative characteristic thermistor manufactured using this thick film negative characteristic thermistor composition.
[0095]
(A) By reducing defects generated during firing of the thick film negative characteristic thermistor, short-circuiting between electrodes due to defects is prevented, and product yield is improved. In addition, it is possible to prevent life deterioration due to moisture intrusion into the defect.
[0096]
(B) Since a B constant equivalent to a conventional one and a wider range of sheet resistance values can be obtained, the conventional thick film negative characteristic thermistor paste can be replaced without requiring a large design change.
[0097]
【The invention's effect】
As described above, when a thermistor composition is produced according to the method for producing the thermistor composition of the present invention, and the thermistor is produced using this composition, the occurrence of defects inside the thermistor film can be suppressed. it can.
[Brief description of the drawings]
FIG. 1 is a diagram showing a method for producing a composition for a thermistor according to the present invention.
FIG. 2 is a diagram showing a method for manufacturing an NTC thermistor.
FIG. 3 is a view showing a blending ratio of each metal oxide.
FIG. 4 is a view showing a blending ratio of an NTC thermistor composition.
FIG. 5 is a diagram showing a mixing ratio of glass.
FIG. 6 is a diagram showing the relationship between glass composition and various characteristics of an NTC thermistor.
FIG. 7 is a diagram showing the relationship between glass composition and various characteristics of an NTC thermistor.
8 is a scanning electron micrograph of a cut surface of a sample 502. FIG.
FIG. 9 is a cut surface of an NTC thermistor.
FIG. 10 is a diagram showing a method for producing an NTC thermistor composition.
FIG. 11 is a scanning electron micrograph of a cut surface of an NTC thermistor (Comparative Sample 5).
[Explanation of symbols]
30 NTC thermistor
33 NTC thermistor composition
34 NTC thermistor membrane
101 Insulating substrate
102 first electrode
104 Second electrode
105 glass
106 Outer coating
108 void or pinhole

Claims (5)

A metal oxide having a thermistor characteristic and a first component obtained by at least two mixed firing, and ruthenium oxide as a conductive material, in the composition of the thermistor made of a glass component which is an insulating material And
20 to 50% by weight of the first component raw material powder, 1 to 20% by weight of the ruthenium oxide, and 40 to 60% by weight of the glass component,
The glass component is composed of a highly softened glass having a glass softening point higher than 700 ° C. and a low softened glass having a glass softening point of 700 ° C. or less. Highly softened glass: low softened glass = 25-50% by weight: 75-50 A composition characterized in that it is prepared in a weight percent formulation. 2. The composition according to claim 1 , wherein the raw material powder of the high softening glass is prepared to have an average particle size of 2 μm, and the raw material powder of the low softening glass is prepared to have an average particle size of 0.5 μm . The first component, Mn, Co, Fe, A composition according to claim 1 or claim 2, characterized in that it comprises at least two kinds of Ni respective oxides. Preparation of metal oxide and a first component obtained by at least two mixed firing, and ruthenium oxide as a conductive material, composition of thermistor made of a glass component which is an insulating material having a thermistor characteristic A method,
A preparation step of adjusting the glass component;
The raw material powder of the first component that is 20 to 50% by weight of the composition, the ruthenium oxide that is 1 to 20% by weight of the composition, and the glass component that is 40 to 60% by weight of the composition In the step of preparing the glass component, the highly softened glass having a glass softening point higher than 700 ° C. is crushed into a raw material powder having an average particle size of 2 μm, and the glass softening point is 700 ° C. or lower. The low softened glass is pulverized into a raw material powder having an average particle size of 0.5 μm, and then mixed into a blend of high softened glass: low softened glass = 25-50 wt%: 75-50 wt%. A method for producing a thermistor composition. A first electrode formed on one surface of a predetermined size insulating substrate;
Using the composition for the thermistor according to any one of claims 1 to 3 , a functional film formed to overlap the first electrode;
A second electrode formed to overlap the functional film;
A thermistor characterized by comprising:

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