JPS6072201A - Moisture sensitive resistor composition - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a highly sensitive moisture-sensitive resistor composition that does not change over time even in a corrosive gas atmosphere.

[Background of the invention]

Moisture sensing elements are used, for example, to detect humidity in air conditioning equipment.
The moisture sensitive part is placed directly exposed to the measurement atmosphere.

For example, the above measurement atmosphere may be H,
There are atmospheres where corrosive gases such as S are always present, and places where there is heavy traffic, where corrosive gases such as NO2 and 502 emitted from automobiles are always present.

Even when used as a moisture-sensitive element, it is exposed to an atmosphere of these corrosive gases for a long period of time.

It is necessary that no errors occur over time.

As a conventional metal oxide moisture sensitive resistor material, lNl
N11-xF+xoa ceramic, FgxOs-D
o ceramic and Mρ204-Ti (h ceramic, etc.) were used.

These ceramics all have IhS, S(h
.

There is a drawback that the ceramic surface is eroded by corrosive gases such as NO2, and the moisture sensitivity characteristics drift, resulting in a humidity detection error that increases over the course of one hour.

On the other hand, these ceramics cannot be sintered in a normal thick film process due to their high sintering temperatures.
As a binder, it is necessary to use glass or binder.

However, if a glass binder is used, the resistance value increases and the sensitivity of the moisture-sensitive element decreases, which is undesirable.In the end, if the above-mentioned ceramic is used as a moisture-sensitive resistance composition material, the resistance value becomes large and the sensitivity of the moisture-sensitive element decreases. For these reasons, currently, in the field of air conditioning equipment, which is used in harsh environments and requires relatively high precision, thick film technology is being used to improve mass productivity, reduce costs, and The reality is that it is not possible to improve element accuracy.

[Purpose of the invention]

The present invention solves the above-mentioned conventional drawbacks.

Lower firing temperatures make it possible to use thick film technology.

It is an object of the present invention to provide a moisture-sensitive resistor composition that eliminates drift in moisture-sensitive characteristics with respect to corrosive gases and is excellent in terms of mass productivity, low cost, and high precision.

[Summary of the Invention] That is, the present invention uses a moisture-sensitive resistor material that can be sintered at a low temperature of 1000 υ or less without using conventional ceramics as a moisture-sensitive resistor material and without using a glass binder. Furthermore, a corrosion-resistant material is added to this to make a thick-film moisture-sensitive element with excellent corrosion resistance, and the humidity-sensitive resistor composition is a hubnerite-type or celite-type metal oxide MFo4 ( M in the formula is Kn, Co, 'F
g, Ni.

My, Ca, Ba, Sr, Zn,
It is characterized in that 0.6 to 7.5 parts by weight of Nb2O5 or 03 to 5.2 parts by weight of GgO2 is added as a corrosion-resistant additive to 100 parts by weight of at least one metal among Pb.

[Embodiments of the invention]

First, using FIG. 1, the moisture-sensitive resistor material MnWO
The change in humidity detection error over time in a corrosive atmosphere when 20S or Gg 02 is added will be explained.

In the figure, the moisture-sensitive resistor is made by adding 6 parts by weight of N1rOs to 100 parts by weight of MnWO4 (straight line 2 in the figure), and the same (straight line 2 in the figure) is obtained by adding Ge (to 100 parts by weight of MnWOa).
6.5 parts by weight of H (straight line 5 in the figure), and M
Three moisture-sensitive resistors containing only 100 parts by weight of nWOa with no additives (straight line 1 in the figure) were prepared, and were mixed with IhS of 0.5 ppm, S (h of 1 ppn, )i02 of 1
ppm.

Temperature 30, humidity 75% I? The change in humidity detection error over time was measured at a temperature of 25° C. and a humidity of 50% ff when the device was left in a corrosive H gas atmosphere.

As a result, those without additives (straight line 1).

As time passes, the humidity detection error increases to 1100
After the lapse of time, a humidity detection error of 20% RH or more occurred.

On the other hand, when Nb2O5 is added (straight line 2), 1
Within 5% RH after 00 hours, with GgO2 added (straight line 5), the humidity detection error is within 6% RE after 100 hours, and the addition of Nb2O5 or GgO2 provides extremely corrosion resistance. It was found that it improved.

As described above, the reason why the durability against corrosive gases was improved by adding NA3 (Jl! or GgO2 to MWO4) is because of the un site on the surface of the moisture sensitive part.

This is thought to be due to substitution with HA or Gg, which does not easily react with corrosive gases.

Now, let's talk about one invention. The moisture-sensitive resistor is made of a hbnerite type or sealite type metal oxide hfWOa (M in the formula is Kn, Co, Fg, Ni,
up.

100 parts by weight of at least one metal of Ca, Ba, Sr, Zn, PB, Nh2Qs
06 to Z5 parts by weight or Gg (Jh O, 3 to 5.2 parts by weight).

This humidity-sensitive resistor composition hardly changes its humidity-sensitive characteristics even when exposed to an atmosphere containing a corrosive gas, and its resistance value changes greatly due to changes in humidity.

Changes linearly.

Also, do not use a glass binder for the humidity sensing part (10DO
It can be sintered at a low temperature of E or less, and can be made into a high-performance, mass-producible, and low-cost thick-film moisture-sensitive element.

The reason for limiting the contents of the additives Nh20s and GgO2 as described above is as follows.

Nb2O5 0.6 parts by weight or less or Q e 02 03
When the amount is less than 1 part by weight, the change in characteristics that occurs when the humidity sensitive part is exposed to corrosive gas becomes significant, resulting in a large humidity detection error.

Furthermore, when the amount of Nb2O5 added is 15 parts by weight or more or the amount of Gaps added is 5.2 parts by weight or more, the resistance value change with respect to humidity changes becomes small, and the humidity detection accuracy deteriorates.

An embodiment of the present invention will be described in detail below.

FIG. 2 shows the appearance of the thick film humidity sensor used in the experiment of this example. In the figure, 1' is an alumina insulating substrate, 2'
is the resistance heating element, and 5' is the lower electrode.

4' is a moisture sensitive layer, and 5' is an upper electrode.

First, the moisture sensitive layer 4' was made in a first-order manner. As raw materials, MnaOs, NiO, Fo2es, MgO
, CaOBaO, PhO, and ZnO, this was mixed with II'(h, weighed so that the fired product would have a predetermined composition, and wet mixed in an alumina bot mill.This mixture After drying, it was press-molded using PVA as a binder to form a disk with a diameter of 25 m and a thickness of 2 m.

This disk was fired at 800° C. for 2 hours to obtain a sintered body. This sintered body is crushed using a paddle machine and a ball mill.
A moisture-sensitive material powder with a particle size of 0.5 μm to 1 μm was prepared.

A predetermined amount of Nb20b or Gg (
The mixture was weighed and mixed for 6 hours in a rice cooker.

Next, 6 volumes of an organic vehicle consisting of α-terpineol and ethyl cellulose were added to 10 g of the above mixed powder, and the mixture was kneaded again for 2 hours using a milling machine.

The moisture-sensitive material paste thus obtained was printed on the lower electrode 5' using a screen printer to a thickness of 70 μm to form a moisture-sensitive layer 4.

After that, it was dried, and the upper electrode 5 was printed using Pt paste, and fired at 800 yen for 2 hours.

The thick film humidity sensor (sample) created in this way is
H2S is o, 5ppm, S(h is 'PPm*N
A sample was prepared by exposing it for 100 hours to a corrosive gas atmosphere with O2 + ppm rm degree 30V and humidity 75% RH.

Regarding this sample, the change in resistance value at a temperature of 25 C and humidity of 50% RH was measured, and the humidity detection error corresponding to this was calculated. The results are shown in Tables 1 and 2. Table 1 shows Nb20B as an additive.

Table 2 shows the measurement results when GgO2 was used as an additive.

In Table 1, the main component MnWOa (Example sample &1
．． 6 and Comparative Examples 1, 3. <5), we find the following.

First, in Examples 1 and 6, the higher the Nb2O5 content, the more
The humidity detection error is reduced to 5% RH compared to 9% RH.

On the other hand, the sensitivity ranges from 4200%RH to 3500%R
It worsens to H.

Therefore, the higher the content of Nh20G, the smaller the humidity detection error, while the sensitivity tends to be worse.

However, when we look at Comparisons 1 and 3, what we can see about &1 is that when l'1h2Qs is set to 0.5% by weight, even though the sensitivity is not different from that of Example 1, the humidity detection is The error becomes extremely large, and it is assumed that there is a lower limit value for Mhos.

Therefore, from Example &6 (Nb2O5 is 1% by weight) and Comparative Example A I (Nb2Qs is 0.5% by weight), Nb2
It can be seen that the lower limit of the content of O5 is between 0.5 and 1% by weight.

On the other hand, when looking at Comparative Example &5 (Nb2Qs 10% by weight), the sensitivity is extremely poor.

From this, it can be seen that there is an upper limit to the content of Nb2Qs.

That is, when looking at Example A 1 (Nb2Qs is 6% by weight) and Comparative Example 5 (Nb2Qs is 10% by weight), N752
It can be seen that the content of 05 is between 6 and 10% by weight.

In addition, in the main component compositions of Examples & 1 to 15 and Comparative Examples A1 to 9, the sensitivity is 500% RH or more and the humidity detection error is 1.
The range of NM O8 content below 0% RH is 06 to 1
It is 5% by weight.

Next, consider Table 2. In Table 2, Example A14i9 and Comparative Example 10 in which the main component is KnWOa
, 12.

First of all, in the comparison between the test case 14 (Gg (h is 6.5% by weight)) and the same test case 19 (GgO2 is 05% by weight), the humidity detection error is moderate at 6 to 10% RH.
Example A (Ga (h is 0.5% by weight) and comparative example/Ff
Comparing with li 10 (Gt (h is 0.1% by weight),
Ta.

In this case, the humidity detection error is extremely low at 10-16% RH, even though the difference in GeO2 content is small.

It's coming down.

This shows that Gg(h) is sensitive to humidity detection errors in a small range below a certain value.

Moreover, Example 14 (Gg02 is 3.5% by weight) and Comparative Example +
2 (GeO2 is 10% by weight).

Sensitivity becomes extremely poor from 5600 to 400%RH.

It can be seen that the upper limit of the GeO2 content has a sensitive effect on the sensitivity.

As a result of the experiment, the sensitivity was 500% RE or more, and the humidity inspection error was 1.
The GeO2 content below 0% RH is 0.5 to 52
He is in charge of weight.

〔Effect of the invention〕

As detailed above, the moisture sensitive resistor composition of the present invention has the following features:
Even when used in an environment containing corrosive gases, there is no drift in the humidity sensitivity characteristics, and humidity detection errors can be minimized.

Also, since it became possible to use thick film technology Z, mass productivity was improved and the cost was reduced, making it possible to greatly improve the product value.

Furthermore, due to the synergistic effects of the resistance value changing linearly with humidity, the resistance value changing largely with humidity change, and the high reproducibility and no change in resistance value over time, it is highly sensitive and extremely stable. It has excellent effects such as being able to be used as a temperature-sensitive sensor.

[Brief explanation of drawings]

Figure 1 is a diagram showing the humidity detection error when Nb2O2 and Ge(h) with and without additives are left in a corrosive mixed gas.
The figure is a perspective view of the humidity sensor element used in the experiment. 1'... Alumina substrate, 2'... Resistance heating element, 6'
...lower electrode, 4'...moisture sensitive layer, 5'...upper electrode. Fig. 7 粁臁 Poetry M (Ar) Procedural amendment (method) Name of the invention of Patent Application No. 178275 of 1982
Relationship to the case of a person making parabolic correction for moisture-sensitive resistor M Name of patent applicant Name <5101 Co., Ltd. 14 Hitachi Manufacturing Office Representative Subject of amendment Subject of correction 1811 Column for thin-boned spinach trout in Saiso. Contents of correction

Claims (1)

[Claims] Kn, CO, Fg, Ni, My, Ba
, Ca, Sr. Moisture-sensitive resistor composition 100 comprising at least one metal selected from Zn and PB and a metal oxide of WO5
1 part by weight. ．． Nh20. A moisture-sensitive resistor composition characterized in that 0.6 to 7.5 parts by weight of GgO2 or 0.6 to 5.2 parts by weight of GgO2 are added.