JPS5872047A - Humidity sensitive element - Google Patents

Abstract

PURPOSE:To decrease the variations of resistance value and humidity sensitive function, by using a calcined material of an organic silicone compound polymer as humidity sensitive base material and covering its surface by a hardened film of the organic silicone compound polymer having specific thickness. CONSTITUTION:A comb-shaped electrode 2 is subjected to screen printing on an alumina insulation substrate 1 and is baked after attaching a Pt lead wire 4. A filmy humidity sensitive base material 3a is formed thereon as the base material of a humidity sensitive part 3 by calcining the constituent consisting of a prepolymer of methylsilicone as an organic silicone compound polymer, talc alumina as an inorganic powdered particle, a thinner as an additive and an organic titanium compound. After immersing the part 3 in silicone varnish dissolved the prepolymer of methylphenylsilicone in xylene, it is calcined at 200 deg.C to form a hardened silcone resin film 36.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a humidity sensing element that utilizes changes in electrical resistance of a humidity sensing portion due to humidity.

Conventionally, as a moisture sensing part of a humidity sensing element having such a distance, electrolytes such as lithicium chloride and lithium chloride, semiconductor vapor deposited films such as selenium germanicum, and aluminum oxide and titanium oxide have been used.

Iron oxide oxidized ceramics have also been used. In modern times, gold maple compound ceramics are often used because they are mechanically and chemically stable and have high element strength. It is in. Under these circumstances, it has been pointed out at recent academic conferences that no matter how stable the moisture-sensing element is, it has only a limited track record of use and has problems in terms of reliability and longevity. .

Namely.

One is pollution such as cigarette smoke or oil mist.If several layers of #negative are applied to the surface, the resistance value will change greatly and the relative humidity reading will change significantly, making it humid.Moreover, the humidity sensor l]C is low. One thing to do, one more thing to do.

Even if the atmosphere is free from surface contamination such as oil mist, water (moisture) can be absorbed by using it in full atmosphere or by releasing it! When the layer is turned over, the 011 group is eroded (because of the solid layer (several chemical layers) formed on the surface, the resistance value of the element itself changes greatly, and even in this case, humidity can be detected (humidity sensitive).
One thing is that the traffic has decreased. In both cases, if they are not heated to a temperature of 500 to 600° C. (normally 500 to 600° C. or higher), they will not recover to their initial properties. Therefore, in order to solve this problem, some ceramic humidity sensing elements are equipped with a heater for heating the sensor to a temperature of 813,500 DEG C. to 600 DEG C. (2) and its control circuit. But these things? When equipped.

The element itself is also expensive, and it takes a lot of electricity to heat 7AI with one piece of aluminum. The advantage of spending a lot of money was that it also had its drawbacks, and one thing was inevitable.

Invention 8, in order to improve the above points, was investigated using various types of shrines, and it was found that the right wall silicon compound proboscis subassembly was fired at a temperature of 300°C or higher.Moisture sensitivity iA: Shrine.

The surface is coated with a hardened film of organosilicon compound matrix,
Moreover, it has been found that when this film thickness is less than 1000 yen, the above-mentioned drawbacks can be overcome and a humidity sensor suitable for practical use and reliability can be achieved.

The present invention is proposed. In other words, the moisture-sensitive element of the present invention is chemically stable, has high water strength, and has good moisture-sensing characteristics. Even if the change in moisture function is small, and even if both change, heating at a much lower temperature than conventional methods will result in good initial performance
This eliminates the advantage of returning to the original state using the c-casing (3).

Hereinafter, one embodiment of the present invention will be described in detail based on examples.

[Example 1] A comb-shaped electrode was screen-printed using a Pt-PD alloy paste on an aluminum insulating substrate, and a PT lead wire was attached and all post-baking was performed on this.

As a base material for the humidity sensitive part, the following composition was baked at 650° C. for 40 minutes to form a film-like base material for the temperature sensitive part at t+b.

(Composition Example 1) Organosilicon Compound?! 1 Polymer: Methylene Licone First 14
AX Compound 55 Kochubu Muisoga Powder Particles: Talc 51 Alumina
151 Additives: Nonner, organic titanium compound 60 1 The additives are used to improve the mixability and coating properties of the above composition and to promote the hardening of the film.

Tsuki vcl Early type of methylphenylcone (4
Commercially available silicone resin (silicone) varnish made by soaking 91J in xylene and further spreading it with xylene to lower the viscosity, and soaking the upper part of the grip in this varnish with 80% ℃ for 20 minutes, and then baked at 200℃ for 20 minutes to harden the BQ grapes.This work VC
Therefore, it was possible to manufacture a moisture-sensitive element that is based on the first factor. In Fig. 1 (a) VC, the peak is the wire-broken substrate, (2) is the electrode, 131 is the 2 ν capital, (41 is the y-d line, Fig. 1 (
In b (38) + 1'; I, upper d pi composition t%l
The moisture sensitive base (3bJ) is a cured film of silicone resin.The film thickness of the moisture sensitive base H is approximately 6
The thickness of the silicone resin film on the surface was 3μ〃6.

In this way, the moisture-sensitive element of this example was manufactured.

The structure is the same as that of this example above, but there is a
The humidity-sensing characteristics and their changes over time Th dllI were added to the conventional type ceramic moisture-sensing element bonded with i02-Az2C1a yarn ceramic. AC (5011z) 1. To compare the humidity-sensitive characteristic sounds of 9 pixel elements. O
Let V be the electric power n, and calculate the change in FA due to relative humidity change (
5) When we measured the change over time, we obtained the results shown in Figure 2. The concave line (AJ, (AJ) indicates the initial stage of the conventional type and the humidity sensitivity after being left indoors for 80 days, and the Mori (BJ,
Moisture sensitivity characteristics after being left indoors for several days. As is clear from FIG. 2, the resistance value of the conventional type moisture sensing element was as high as 3 digits when the VC was opened for 80 days, and the humidity sensing function was considerably reduced. Immediately after the /% humidity element was left open for 80 days, the resistance value only increased slightly, and no deterioration of the humidity sensing function by 1° was observed. By the way, the characteristics of Curves (A) and (B) are shown in Figure 1. After being left for 80 days, the pixel element was placed in an electric furnace, and the temperature was raised from 150°C in 50°C increments, and heated at each m degree for 10 minutes. Moisture sensitivity characteristic is initial value (N work (B) at 1 IP! Temporary temperature # all investigated. This result.

While the conventional one did not return to its initial characteristics unless heated to 600°C or higher, the nine embodiments had 2.
The initial characteristics were completely restored by heating to 00°C. Therefore, from the above results, it is clear that the device of the present example does not absorb water vapor (moisture J) even if the adsorption/desorption layer (6) is repeated, and even when the OH groups are strongly absorbed, as in the conventional device. It has been found that re-sharpening is possible by heating at a much lower temperature than conventional ones.

[Example 2. ] The same materials as in Example 1 were used for the substrate, electrodes, and lead wires, and the following mparabolic 2. A composition (z40 (calcined at 1° C. for 1 hour) was used.

tmi synthetic parabolite J Organosilicon compound compound: 7 methylphenyl ÷ rice copolymer 65 pairs Distillation-resistant inorganic powder particles Titanium dioxide 251 Magnum oxide 5 # Calorie additive: Nanna, 1 Aluminum compound 7 ul On this surface, apply Keijuki + mk: base resin.

This was diluted with a commercially available modified silicone resin paint thinner modified with the initial saccharide of grape jelly resin, and then applied by applying paint. After drying at 77°C for 20 minutes, it was cured by baking at 150°C for 30 minutes. As a result, a moisture-sensitive element as shown in Fig. 3 was obtained. Fig. 3 In.

The mountain is the insulating substrate, (21 is the electrode, (3) is the moisture sensing part, (4)
(6) is the lead wire, +51 [heater, (6) is the lead wire for the heater. The thickness i of the silicone resin film in Table 1 was 6 μm.

With the element of this example and the same configuration as above,
Regarding the conventional type of moisture sensitive part made by sintering Ti02-MpO thread ceramic, we investigated the reliability of the moisture sensitive property in the presence of surface contaminants. As a deterioration acceleration test, first, commercially available salad oil was placed in the bottom of the desiccator, the above-mentioned pixel was suspended in the atmosphere above the desiccator, the electricity was heated to 60°C, and cigarette smoke was constantly placed inside the desiccator. was left in circulation. After 20 days, the entire pixel element was moved out, AC 1.0 V was applied, and the moisture sensitivity characteristics were added to the gold side.
It was soft compared to the initial characteristics.

These seven results are shown in Figure 4. In Fig. 4.

Song #11 (C), (C)ri 9 curve (cut, (IJj is).

are the characteristics of the two inventive products after initial and accelerated deterioration tests. From the fourth problem, in the case of the conventional type, the resistance 111t of the VC was greater than 3ffr after the accelerated deterioration test, and one humidity sensor was completely lost, whereas the one of the nine embodiments It can be seen that even after the accelerated deterioration test, the resistance value increased somewhat, but there was almost no decrease in the humidity sensor Be. Therefore, in the above test used to accelerate deterioration over time due to surface contamination (QA), even though the test method is harsh, it completely eliminates the humidity detection sensitivity of the conventional type element. %, it can be concluded that the element of this example has very good resistance to deterioration during soaping against contaminants such as oil mist and cigarette smoke.

Next, after the accelerated deterioration test, the heater for the pixel (which shows the characteristics of 9 songs) and (4th section)
The temperature was increased from 0°C to 50°C and heated for 15 minutes at each temperature. As in the case of ., the conventional one has a temperature of 600℃
Although the initial characteristics were not restored unless heated to above, in the case of Example 9, O1 was completely returned to the initial characteristics by heating at a much lower temperature of 250°C.

Example 1. Work 2. The moisture-sensitive element of the present invention, which was found to have good resistance to basic layer properties and 4-to-1 rice grain resistance against pollutants, was found to have a good resistance to dirt [responsive silicone resin, i.e.,
This is thought to be due to the water and oil repellency resulting from the low surface energy of the organic pore compound 'ftJ polymer. However, according to the inventor's experiments, the humidity sensor e is affected by the J# thickness of these side fat films, and as the film thickness increases, the resistance value increases and the humidity sensing function is completely lost. I found out that this is true. In other words, the relative humidity ranges from 10% to 9%.
Figure 5 shows how much the resistance value of the element changes when changed by 5% i. Similar characteristics were observed. Similar characteristics were obtained even when the IOJ of the above-mentioned polymer was varied. Therefore, from Figure 5,
If the film thickness exceeds 10 µ''l'fr:, sharp ridges will appear and the resistance will be lowered, making it difficult to put it into practical use.

91 As a result, the surface rC is assumed to be present in the present invention. 1) Organosilicon compound such as silicon + m4 fat 1 Of course ML
It is necessary that the film thickness of the eight bodies be 10 μL or less.

By the way, in the present invention, the organic silicon compound polymer used as the base material and its surface coated material may include the silicone resin and its varnish used in the Examples. With a scale that can be used / 2 (denatured type of fibrous fat or oil.

All rubber-like so-called/recones can be used. In addition, the above organic
As the inorganic powder particles to be kneaded with VC in the silicon compound polymer, it was confirmed by using dust and dirt that any oxide or gold powder with a low grade can be used.

In the present invention, we conducted similar experiments using other polymers instead of the organosilicon compound polymer that is treated on the surface of the moisture-sensitive part. It was not possible to obtain a good quality vessel, and there was no way to fix it in practical use.As mentioned in the first example, when the element after deterioration is heated completely, other elements are generally added to the upper 5α subcombination. It has a higher heat resistance than polymers (over 200℃)
Therefore, it is advantageous.

As explained above, is the fired product of a mixture of 1M silicon compound polymer and S astringent powder wood particles? If the humidity-sensitive element of the present invention is a moisture-sensitive base material, and the surface thereof is covered with a single-hair coating mainly composed of an organosilicon compound polymer with a film thickness of 10/J/74 F or more, It goes without saying that it has good moisture-sensing characteristics, but even when used in a contaminated atmosphere for many years, there is almost no deterioration of the moisture-sensitive grain or fluctuation of resistance, and even if these two characteristics change, it will be much better than the conventional one. There is PJ7, which returns to its initial performance in 1 by heating at a much lower temperature than the original. Therefore, it can be widely used in various applications as a humidity sensing element such as a humidity sensor or a soot cup.

[Brief explanation of drawings]

FIGS. 1 and 3 show (12) configuration examples of the moisture-sensitive element of the present invention, and FIGS. This is a graph that reveals gender. In addition, in the figure, the same reference numerals indicate the parts corresponding to the same 1 friend, and (1
) is the board, 121 is the electric body, 131 μl wire is used, (41 is the lead wire, +51ri heater, 16) is the heater plate. agent kidnapping ji); 匍 - (133 @2 figure relative; ヱ cliff (γ・9 4th da 5θ / ρρ relative: I, I!j (ヅ□ri 5th
Film thickness and written amendment (method) % formula % 1. Indication of the case Japanese Patent Application No. 56-171835 2. Name of the invention Moisture sensitive element 3. Relationship with the case of the person making the amendment Patent applicant address Tokyo 2-3 Otsu-chome, Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Hitoshi Katayama 4, Agent Name (6699) Patent attorney Shin Kuzuno
- (Contact information: 03 (213) 3421 Patent Department) 5. Date of amendment order: February 23, 1982 6. Drawing subject to amendment 7. Contents of amendment No change (~) Procedural amendment (voluntary) 791 Showa I1゛, Month 11, Name of the invention/!'+m Element 3, Person making the amendment Relationship with the case 'M-Applicant address 111 Chiyo, Tokyo Ward Marunouchi, 12F
fi 3 >-, 'Name (601) Mitsubishi Electric Co., Ltd. Representative Kata 111 Jin Hachibu 4, Agent address 1 Ku no Uchizume, Chiyo 111-ku, Tokyo, r
, + 2-7% No. 3.5 Claims and Detailed Description of the Invention column of the specification subject to amendment. 6. Contents of amendment (1) Nine amendments are made to the scope of claims in the specification as shown in the attached sheet. (2) On page 2, line 20 of the specification, [Moisture sensing section 50 (1-60
0℃" and Arono [humidity sensitive part 500. -600℃]. (3) Same as above, page 3, lines 16 to 17, “Of course,
'' is corrected to ``Of course.'' Claims above: A baked product of a mixture of an organosilicon compound polymer and inorganic powder particles is used as a moisture-sensitive base material, and the surface of this moisture-sensitive base material has a film thickness of 1
An Ie, i element characterized in that it is coated with a cured film mainly composed of an organosilicon compound polymer having a diameter of 0 μm or less.

Claims (1)

[Claims] Organic silicon compound +) lJ rin aggregate mixed with inorganic substance @ Fuyuko as a moisture-sensitive base material, and the surface of this moisture-sensitive base material is an organosilicon compound polymer with a film thickness of 10 μm or less. A moisture-sensitive element characterized by being ruptured with a cured Ft film containing as a main component.