JPS5873101A - Humidity sensitive resistance 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 The present invention relates to a moisture-sensitive resistor composition comprising manganese oxide and tungsten oxide, and particularly to a moisture-sensitive resistor composition that shows little change over time.

By heating the conventionally known electrical resistance type humidity sensor element, it is possible to recover the change in characteristics due to the adhesion of organic contaminants to the smoke of agricultural machinery and oily cigarettes. It has advantages such as being able to recover changes in properties over time due to chemisorption. but,
Ceramic-based humidity sensors require an easy way to support the element.On the other hand, the fi1 degree sensor made on a ceramic substrate using the thick JiX manufacturing process has a high substrate strength, so the way to support the element is easy. It has excellent mass productivity because it can be connected to the device and electrode terminals using wire bonds like normal semiconductor devices.

Thick-film humidity-sensitive resistors are made of metal oxide-based humidity-sensitive resistor porcelain powder whose resistance value changes depending on humidity, glass frit, butyl cellulose or ethyl cellulose-based 1F binder, etc.
A moisture-sensitive resistor paste is prepared by mixing the two in appropriate proportions, and this is then deposited into a normal thick film. This thick film humidity-sensitive resistor made of porcelain powder and glass frit has a low sensitivity and a high resistance value because it contains binder glass. As a solution to this drawback, the sintering temperature is low and no glass binder is required.
Manganese tungstate MfO was discovered. Thick film humidity sensor using manganese tungstate is made of ceramics! ! #- This is an excellent senna that can remove contaminants such as mold by heating cleaning, recover from aging by chemically adsorbing moisture, and has the characteristics of thick film, such as high mass productivity and low cost.

However, like conventional ceramic humidity sensors, they have the disadvantage of requiring frequent heating and cleaning to restore their properties, since their characteristics change over time due to chemical adsorption of water. .

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art,
The whole moisture-sensitive resistor composition used in a thick film temperature sensor is reduced to #[' of cleaning link to recover the sound change over time of characteristics by slowing down the change in characteristics due to chemical rIIL adhesion of water. It is about providing.

The moisture-sensitive resistor composition of the present invention is characterized by manganese oxide (e.g., Mn, U, Mn, he, Mn, U
,,Mn (J, Hiro) and tungsten oxide (for example, p' et al.) and tubes, the value of W/Mn is 1,200 in terms of the total molar ratio of metallic tungsten to metallic manganese.
~1,005, or East 995 ~
It consists in including any of the books within the range of ζ800. By using the composition of the present invention, it is possible to obtain a moisture-sensitive resistor gold that shows little change over time.

The present inventors have prepared trimanganese tetroxide Mn, 0. A detailed analysis and study of the composition ratio and the formation rate of surface hydroxyl groups at a constant humidity of 50% H at 24°C and tungsten trioxide F (/, As a result, the present invention was completed.That is, tungsten-European manganese with various composition ratios were heated at soo'c for 10 minutes to remove surface hydroxyl groups that had occurred due to water chemisorption, and then 50% When left in a constant humidity of %H, the rate of formation of surface hydroxyl groups with the passage of time is 4 oscillations in the infrared absorption spectrum of a tube!Illumination and investigation of weight changes using an electronic ultra-microbalance according to this I@Chen. Ba,
As time passes, the infrared absorption intensity due to J vibration becomes stronger.
The weight also increased gradually in J14. This phenomenon shows that moisture in the air is chemically adsorbed onto the surface of manganese tungstate, and hydroxyl groups are gradually formed over time. It has been revealed that the rate of formation of surface hydroxyl groups depends on the composition ratio of manganese tungstate, and the higher the proportion of tungsten oxide or manganese oxide, the slower the rate of formation of surface hydroxyl groups. Therefore, based on these survey results, we measured the change in resistance value over time in the humidity of Nagi, and found that the composition ratio of manganese tungstate or the molar ratio of metal is 1/7M%.
, 200 to 1,005 books, or 995 to 800
It has become clear that the change in resistance value over time is small, and that the degree of heating required to recover the characteristics can be reduced compared to conventional methods. molar ratio of metal r
7m% is smaller than 1.005 and larger than ζ995 1
The resistance value changes significantly over time and must be heated and cleaned at least five times a day. Further, if the metal molar ratio W/Mts exceeds 1.200, not only the resistance value changes over time but also the resistance value of the element becomes large. When the molar ratio of metal is less than 800, not only does the change in resistance value over time become large.

Because the sintering temperature of manganese tungstate is high, it becomes impossible to form a thick film.

Hereinafter, the present invention will be explained in more detail with reference to test examples. The test examples are samples 1 to 9, among which 2 to 9.
7 is according to the present invention, 1, B%9 is not according to the present invention.

Test Example First, trimanganese tetroxide and tungsten trioxide powders with a purity of 99.9% or higher were prepared as starting materials.

These were collected so that the composition ratio corresponded to the composition of the nine poles of paper materials No. 1 to 9 in Table 1.

Each of the formulations was processed as follows.

The mixture was dry mixed in an agate mortar for 6 hours. After the mixing was completed, the mixture was taken out from the crusher and a disk was formed by applying a pressure of 150 Qfy/c-. This molded body was fired in air at a temperature of 1100'C for 2 hours.

The compact was roughly crushed in a tube agate mortar for 6 hours, and then finely crushed in a planetary ball mill for 8 hours. After the grinding session was completed, the ground material was taken out of the pot and dried.

Next, an α-terpineol solution containing 10 weight s of ethyl cellulose was used as an organic binder to give a pulverized product of 1°! Naotashi,
Scc and kneaded in an alumina mortar for 2 hours to obtain a moisture-sensitive resistor paste.

On the other hand, a platinum-based conductive paste was screen printed on the Aluna substrate and baked at 1100'C for 2 hours to obtain a heating cleaning heater. platinum base on the opposite side of the heater)? The lower electrode was printed and fired using this method. Next, after printing and drying the moisture-sensitive resistor paste on this lower electrode, an upper electrode was printed using platinum paste, dried, and baked at 1100°C for 2 hours to form a moisture-sensitive resistor layer on both the upper and lower sides. A thick-film moisture-sensitive resistor with a sandwich structure sandwiched between electrodes was formed.

For each of the nine types of humidity sensors shown in the table shown in the table below, each of which had a different composition ratio of manganese tungstate, the changes over time at a humidity of 50% H were investigated.

The result is shown in the graph of the chart. Each curve in the V diagram is 1. This figure shows the change over time in the resistance value of M)0, -FO, type thick film thermal sensors of each composition shown in the table. This is a book that corresponds to sample No. 11 of the W Ashi table with the numerical code attached to each square in Figure 1.

It is clear from the graph of the liability diagram that the value of 11'1M path is 1,00 when converted to the molar ratio of metal in sample 1.
For those with a composition ratio of 0, the resistance changes significantly over time, and therefore, in order to accurately detect humidity, the characteristics must be restored frequently by heating and cleaning.

As in Samples 2 to 7, which have an uninvented composition @, the value of W/)d is 1.200 to 1 in terms of metal molar ratio.
．． 005 or within the range of ζ995 to ζ800 is humidity detection based on resistance change over time - 5% M in 24 hours
Even if heating cleaning is not performed frequently, accurate measurements can still be made.

For example, for sample number 2, the detection difference ri when cleaning is performed with a 24-hour allocation is within 2.5%H. On the other hand, samples 1 in which Nos. 8 and 9 1, Shital 11 exceeded 1.2001, or those with a composition of Q less than 800 and not according to the present invention, showed a change in resistance value over time. The detection error due to this is 5% or more in 24 hours, making it impossible to measure humidity with high precision.

As described above, when converting the composition ratio of manganese oxide and tungsten oxide to the molar ratio of metal, which makes the composition of the moisture-sensitive resistor inventive, the value of TI'/M% is 1.200 to 1.
,005 or ζ995~Q, 80
If it is within the range of 0, it is possible to obtain a thick film & 1 degree sensor with little change in resistance value over time.

As described above, by using the humidity-sensitive resistor composition of the present invention, there is no change in resistance value over time, and highly accurate humidity measurements can be performed without frequent cleaning to recover the characteristics. It is possible.

[Brief explanation of the drawing]

'IN, The figure is a graph showing the change in resistance value over time of each thick-film humidity sensor using the humidity-sensitive resistor composition of the present invention and that using a composition outside the scope of the present invention. .

Claims (1)

[Claims] II'
1. A moisture-sensitive resistor composition, characterized in that the composition contains a composition having a value of 7 Mm in the range of 1,200 to 1.005 F) or in the range of ζ995 to ζ800.