JP2870862B2 - Quartz crystal humidity sensor and its improvement method - Google Patents
Quartz crystal humidity sensor and its improvement methodInfo
- Publication number
- JP2870862B2 JP2870862B2 JP25485889A JP25485889A JP2870862B2 JP 2870862 B2 JP2870862 B2 JP 2870862B2 JP 25485889 A JP25485889 A JP 25485889A JP 25485889 A JP25485889 A JP 25485889A JP 2870862 B2 JP2870862 B2 JP 2870862B2
- Authority
- JP
- Japan
- Prior art keywords
- humidity
- plasma
- humidity sensor
- polymerized film
- film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000010453 quartz Substances 0.000 title claims description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims description 15
- 238000000034 method Methods 0.000 title claims description 6
- 239000013078 crystal Substances 0.000 title description 11
- 150000003961 organosilicon compounds Chemical class 0.000 claims description 7
- 125000003545 alkoxy group Chemical group 0.000 claims description 4
- 230000035945 sensitivity Effects 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000006116 polymerization reaction Methods 0.000 description 4
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000005494 condensation Effects 0.000 description 3
- 238000009833 condensation Methods 0.000 description 3
- 229920006254 polymer film Polymers 0.000 description 3
- 229910052709 silver Inorganic materials 0.000 description 3
- 239000004332 silver Substances 0.000 description 3
- 238000007791 dehumidification Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229920005597 polymer membrane Polymers 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 229920002818 (Hydroxyethyl)methacrylate Polymers 0.000 description 1
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- WOBHKFSMXKNTIM-UHFFFAOYSA-N Hydroxyethyl methacrylate Chemical compound CC(=C)C(=O)OCCO WOBHKFSMXKNTIM-UHFFFAOYSA-N 0.000 description 1
- 229910003849 O-Si Inorganic materials 0.000 description 1
- 229910003872 O—Si Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- NKSJNEHGWDZZQF-UHFFFAOYSA-N ethenyl(trimethoxy)silane Chemical compound CO[Si](OC)(OC)C=C NKSJNEHGWDZZQF-UHFFFAOYSA-N 0.000 description 1
- MBGQQKKTDDNCSG-UHFFFAOYSA-N ethenyl-diethoxy-methylsilane Chemical compound CCO[Si](C)(C=C)OCC MBGQQKKTDDNCSG-UHFFFAOYSA-N 0.000 description 1
- BFXIKLCIZHOAAZ-UHFFFAOYSA-N methyltrimethoxysilane Chemical compound CO[Si](C)(OC)OC BFXIKLCIZHOAAZ-UHFFFAOYSA-N 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000009738 saturating Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- CPUDPFPXCZDNGI-UHFFFAOYSA-N triethoxy(methyl)silane Chemical compound CCO[Si](C)(OCC)OCC CPUDPFPXCZDNGI-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、水晶振動子湿度センサおよびその改善方法
に関する。更に詳しくは、水晶振動子の表面にプラズマ
重合膜を形成せしめた水晶振動子湿度センサおよびその
改善方法に関する。The present invention relates to a quartz oscillator humidity sensor and a method for improving the same. More specifically, the present invention relates to a quartz oscillator humidity sensor having a plasma polymerized film formed on the surface of a quartz oscillator and a method for improving the same.
〔従来の技術〕および〔発明が解決しようとする課題〕 水晶振動子の表面にプラズマ重合膜、具体的には２−
ヒドロキシエチルメタクリレートのプラズマ重合膜ある
いはアクリロニトリルプラズマ重合膜の環元処理膜など
を形成させた水晶振動子湿度センサが、先に本出願人に
よって提案されている（特開昭62−118,237号公報およ
び同64−57,143号公報）。これらの水晶振動子湿度セン
サは、主に相対湿度30〜90％の領域内での湿度の測定に
向けられている。[Prior Art] and [Problems to be Solved by the Invention] A plasma polymerized film, specifically 2-
A quartz oscillator humidity sensor in which a plasma-polymerized film of hydroxyethyl methacrylate or an acrylonitrile plasma-polymerized film is formed has been previously proposed by the present applicant (JP-A-62-118237 and JP-A-62-118237). No. 64-57,143). These quartz oscillator humidity sensors are mainly intended for measuring humidity within the range of 30 to 90% relative humidity.
本発明の目的は、相対湿度が０〜100％の領域内、特
に30％以下の低湿度領域で良好な感度を示す水晶振動子
湿度センサを提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a quartz resonator humidity sensor that exhibits good sensitivity in a region where the relative humidity is in a range of 0 to 100%, particularly in a low humidity region of 30% or less.
かかる本発明の目的は、水晶振動子の表面にアルコキ
シ基含有有機けい素化合物のプラズマ重合膜を形成せし
めた水晶振動子湿度センサによって達成される。The object of the present invention is achieved by a quartz oscillator humidity sensor having a plasma-polymerized film of an organosilicon compound containing an alkoxy group formed on the surface of the quartz oscillator.
水晶振動子としては、ATカット、振動周波数5MHz以上
のものが好んで用いられ、それの使用態様の一例が第１
図に平面図として示されており、例えば表面積が約0.64
cm2の水晶面１の中央両面に銀電極2,2′が取付けられ、
それぞれの銀電極からリード線3,3′が引き出されてい
る。As the crystal unit, those having an AT cut and a vibration frequency of 5 MHz or more are preferably used.
It is shown as a plan view in the figure, for example, with a surface area of about 0.64
Silver electrodes 2, 2 'are attached to both sides of the center of the crystal face 1 of cm 2 ,
Lead wires 3, 3 'are drawn out of the respective silver electrodes.
水晶振動子の表面、一般には両表面へのプラズマ重合
膜の形成は、ビニルトリメトキシシラン、ビニルメチル
ジエトキシシラン、メチルトリエトキシシランなどのア
ルコキシ基含有有機けい素化合物を通常のプラズマ重合
法によってプラズマ重合させることによって行われる。The formation of a plasma polymerized film on the surface of the crystal unit, generally on both surfaces, is carried out by the usual plasma polymerization method using an alkoxy group-containing organosilicon compound such as vinyltrimethoxysilane, vinylmethyldiethoxysilane, or methyltriethoxysilane. This is performed by plasma polymerization.
即ち、水晶振動子をプラズマ反応容器内に設置し、10
-4Torrのオーダー迄反応容器内を排気した後、有機けい
素化合物モノマーを約0.04〜0.2Torrの圧力になる迄導
入し、高周波電源RFにより数10W程度の電力を供給して
数10分間プラズマ重合反応を行い、厚さ約2000〜10000
Åのプラズマ重合膜を形成させる。That is, the quartz oscillator is installed in the plasma reaction vessel, and 10
After evacuation of the reaction vessel to the order of -4 Torr, an organosilicon compound monomer was introduced until the pressure reached about 0.04 to 0.2 Torr, and a power of about tens of watts was supplied by a high-frequency power source RF to perform plasma for several tens of minutes. Perform polymerization reaction, thickness about 2000-10,000
The plasma polymerized film of Å is formed.
形成された有機けい素化合物のプラズマ重合膜は、導
電性基板面との接着性にすぐれ、特にアルコキシ基を含
有する有機けい素化合物は、重合膜の堆積速度が大き
く、また膜中にSi−Ｏ−Si結合を形成させるために強固
な膜を形成させる。The plasma polymerized film of the formed organosilicon compound has excellent adhesiveness to the conductive substrate surface, and in particular, the organosilicon compound containing an alkoxy group has a high deposition rate of the polymerized film, and the film contains Si- A strong film is formed to form an O-Si bond.
このようにして形成されたプラズマ重合膜を用いた感
湿素子は、下記記載の如く特に低湿度領域において良好
な感度を示すものの、初期特性においては増湿時と減湿
時とで若干のヒステリシスを有している。Although the humidity sensitive device using the plasma polymerized film formed in this manner exhibits good sensitivity particularly in a low humidity region as described below, the initial characteristics show a slight hysteresis between when the humidity increases and when the humidity decreases. have.
ヒステリシスの原因は、主として高湿時に吸湿した水
分が感湿膜中へ溶解してしまい、これが減湿時に脱離し
難くなるためと考えられ、そのための対策としては、従
来より感湿素子を定期的に加熱するなどの手段が用いら
れている。しかしながら、こうした手段は、加熱クリー
ニングに余分な電力を必要とし、熱に対して弱い高分子
膜には不向きといった問題点を残している。The cause of hysteresis is considered to be that moisture absorbed at high humidity is mainly dissolved in the moisture-sensitive film, and it is difficult to desorb at the time of dehumidification. For example, means such as heating is used. However, such a method requires extra power for heating and cleaning, and has a problem that it is not suitable for a polymer film which is weak against heat.
本発明においては、形成されたプラズマ重合膜を温度
約50℃以上、相対湿度約80％以上の高温高湿雰囲気中に
少なくとも５時間以上放置することにより、初期特性と
して有しているヒステリシスを軽減すると共に、相対湿
度に対する感度の向上をも図っている。In the present invention, the formed plasma polymerized film is left in a high-temperature and high-humidity atmosphere having a temperature of about 50 ° C. or more and a relative humidity of about 80% or more for at least 5 hours to reduce the hysteresis which is an initial characteristic. In addition, the sensitivity to relative humidity is improved.
上述の如く、一般に増湿時と減湿時におけるヒステリ
シスの存在は、感湿膜中における吸着水分子の毛管凝縮
に起因する。有機けい素化合物のプラズマ重合膜におい
ても、中湿度（約40〜70％RH）以上の雰囲気中において
は、水分子は高分子膜表面に多分子層的に吸着し、特に
高湿度域（約70％RH以上）では、吸着水分子が高分子膜
表面より内部に溶解し、毛管凝縮を生ぜしめている。As described above, generally, the existence of hysteresis at the time of increasing and decreasing the humidity is caused by the capillary condensation of the adsorbed water molecules in the moisture-sensitive film. Even in a plasma polymerized film of an organosilicon compound, water molecules are adsorbed on the surface of the polymer film in a multi-layered manner in an atmosphere having a medium humidity (about 40 to 70% RH) or higher, and particularly in a high humidity region (about Above 70% RH), the adsorbed water molecules dissolve inside the polymer membrane surface, causing capillary condensation.
そこで、予め感湿膜を約50℃以上、約80％RH以上の高
温高湿中に長時間放置し、多分子層吸着域における高分
子膜中への水分子の溶解を積極的に生じさせ、ヒステリ
シスの原因となる毛管凝縮を飽和状態とさせることによ
り、ヒステリシスを軽減することができる。Therefore, the moisture-sensitive film is left in a high-temperature and high-humidity environment of about 50 ° C or more and about 80% RH or more for a long time to actively dissolve water molecules into the polymer film in the multi-layer adsorption zone. Hysteresis can be reduced by saturating capillary condensation which causes hysteresis.
同時に、感湿膜を高温高湿中に放置することにより、
水分子が大量に吸着されて高分子膜が膨潤すると共に、
高分子内における極性基同志の結合が切断され、水分子
の吸着に寄与する極性基数が増加するようになるので、
水分子の吸着量が増加し、感湿膜としての感度も向上す
る結果となる。At the same time, by leaving the moisture sensitive film in high temperature and high humidity,
A large amount of water molecules are adsorbed and the polymer membrane swells,
Since the bond between polar groups in the polymer is broken, the number of polar groups contributing to the adsorption of water molecules increases,
As a result, the amount of water molecules adsorbed is increased, and the sensitivity as a moisture-sensitive film is also improved.
本発明に係る水晶振動子湿度センサは、相対湿度０〜
100％の領域内で良好な感度を示し、10％RH当りの周波
数変化量は、０〜30％RHの領域内で約−244Hz、または3
0〜80％RHの領域内で約−114Hzと、特に低湿度領域内で
良好な感度を示すという特徴がみられる。The quartz oscillator humidity sensor according to the present invention has a relative humidity of 0 to 0.
It shows good sensitivity in the region of 100%, and the frequency change per 10% RH is about -244 Hz or 3 in the region of 0 to 30% RH.
There is a characteristic that the sensitivity is about -114 Hz in the range of 0 to 80% RH, and particularly, it shows good sensitivity in the low humidity range.
また、形成されたプラズマ重合膜を予め高温高湿雰囲
気中で処理することにより、初期特性における増湿・減
湿時のヒステリシスの軽減および感度の向上というなお
一層の素子性能の改善を図ることができる。Further, by treating the formed plasma polymerized film in a high-temperature and high-humidity atmosphere in advance, it is possible to further reduce the hysteresis at the time of humidification and dehumidification in the initial characteristics and improve the device performance such as improving the sensitivity. it can.
次に、実施例について本発明を説明する。 Next, the present invention will be described with reference to examples.
実施例１ 第１図に示される形状の水晶振動子（ORION製、ATカ
ット、10.170MHz）をプラズマ反応容器内に設置し、10
-4Torrのオーダー迄反応容器内を排気した後、メチルト
リメトキシシランを0.08Torrの圧力になる迄導入し、高
周波電源RFにより60Wの電力を供給して30分間、周波数1
3.56MHzの高周波を照射してプラズマ重合反応を行い、
厚さ約8000Åのプラズマ重合膜を形成させた。Example 1 A crystal oscillator (AT cut, 10.170 MHz, manufactured by ORION) having the shape shown in FIG.
After evacuating the reaction vessel to the order of -4 Torr, methyltrimethoxysilane was introduced until the pressure reached 0.08 Torr, and a power of 60 W was supplied by a high frequency power supply RF for 30 minutes at a frequency of 1
Irradiate 3.56MHz high frequency to perform plasma polymerization reaction,
A plasma polymerized film having a thickness of about 8000 mm was formed.
このようにして表面にプラズマ重合膜を形成させた１
個の水晶振動子４を用いた周波数測定回路の一例が第２
図に示されており、測定された周波数は周波数カウンタ
ー５によって計測されるようにした周波数測定装置を30
℃の恒温恒湿槽中に設置し、相対湿度に対する周波数変
化量を測定した。第３図のグラフにその測定結果が示さ
れるように、相対湿度10％当り約−244Hz（０〜30％R
H）または約−114Hz（30〜80％RH）の周波数変化量が示
され、相対湿度と周波数変化量との間に良好な相関関係
が認められた。また、この水晶振動子湿度センサを、相
対湿度90％の雰囲気中に48時間放置したが、感湿膜の剥
離現象はみられなかった。A plasma polymerized film was formed on the surface in this way.
An example of a frequency measurement circuit using two crystal units 4 is a second example.
As shown in the figure, the measured frequency is measured by a frequency counter 5 using a frequency measuring device 30.
The sample was placed in a constant temperature and humidity chamber at a temperature of ℃, and the amount of frequency change with respect to the relative humidity was measured. As shown in the graph of FIG. 3, the measured result is about -244 Hz (0 to 30% R / 10% relative humidity).
H) or about -114 Hz (30 to 80% RH) frequency change, indicating a good correlation between relative humidity and frequency change. In addition, when this quartz oscillator humidity sensor was left in an atmosphere at a relative humidity of 90% for 48 hours, no peeling phenomenon of the moisture-sensitive film was observed.
実施例２ 実施例１において、プラズマ重合膜を表面に形成させ
た水晶振動子を、65℃、95％RHの雰囲気中に27時間放置
した後、相対湿度に対する周波数変化量を測定した。Example 2 In Example 1, the crystal oscillator having the plasma polymerized film formed on the surface was allowed to stand in an atmosphere of 65 ° C. and 95% RH for 27 hours, and the amount of frequency change with respect to relative humidity was measured.
測定結果は、第４図のグラフに○で示され、その結果
から初期の感湿特性（●で示される）に比べて、高温高
湿雰囲気中に放置した素子は、増湿・減湿時におけるヒ
ステリシスが殆んどみられなくなったばかりではなく、
相対湿度に対する感度も向上していることが分かる。The measurement results are indicated by a circle in the graph of FIG. 4, and the results indicate that the element left in a high-temperature and high-humidity atmosphere is less humidified and dehumidified than the initial moisture-sensitive characteristics (indicated by a circle). Not only has hysteresis almost disappeared in
It can be seen that the sensitivity to relative humidity is also improved.
第１図は、本発明で用いられる水晶振動子の一態様の平
面図である。第２図は、本発明に係るプラズマ重合膜形
成水晶振動子の周波数測定回路の一例である。また、第
３〜４図は、それぞれ実施例１〜２における相対湿度と
周波数変化量との関係を示すグラフである。 （符号の説明） イ……水晶面 ２……銀電極 ４……プラズマ重合膜形成水晶振動子 ５……周波数カウンターFIG. 1 is a plan view of one embodiment of a crystal resonator used in the present invention. FIG. 2 is an example of a frequency measuring circuit of the crystal unit formed with a plasma polymerized film according to the present invention. FIGS. 3 and 4 are graphs showing the relationship between the relative humidity and the amount of frequency change in Examples 1 and 2, respectively. (Explanation of symbols) A: Crystal surface 2: Silver electrode 4: Plasma-polymerized film-formed crystal oscillator 5: Frequency counter
Claims (2)
機けい素化合物のプラズマ重合膜を形成せしめてなる水
晶振動子湿度センサ。1. A quartz oscillator humidity sensor having a plasma-polymerized film of an organosilicon compound containing an alkoxy group formed on the surface of the quartz oscillator.
温度約50℃以上、相対湿度約80％以上の高温高湿雰囲気
中に放置することを特徴とする水晶振動子湿度センサの
改善方法。2. The plasma polymerized film formed in claim 1,
A method of improving a quartz oscillator humidity sensor, characterized by leaving the device in a high-temperature, high-humidity atmosphere with a temperature of about 50 ° C or more and a relative humidity of about 80% or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25485889A JP2870862B2 (en) | 1989-09-08 | 1989-09-29 | Quartz crystal humidity sensor and its improvement method |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1-233159 | 1989-09-08 | ||
| JP23315989 | 1989-09-08 | ||
| JP25485889A JP2870862B2 (en) | 1989-09-08 | 1989-09-29 | Quartz crystal humidity sensor and its improvement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03175395A JPH03175395A (en) | 1991-07-30 |
| JP2870862B2 true JP2870862B2 (en) | 1999-03-17 |
Family
ID=26530882
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25485889A Expired - Fee Related JP2870862B2 (en) | 1989-09-08 | 1989-09-29 | Quartz crystal humidity sensor and its improvement method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2870862B2 (en) |
-
1989
- 1989-09-29 JP JP25485889A patent/JP2870862B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03175395A (en) | 1991-07-30 |
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