JPH0743331A - Thick film gas sensor - Google Patents
Thick film gas sensorInfo
- Publication number
- JPH0743331A JPH0743331A JP20350793A JP20350793A JPH0743331A JP H0743331 A JPH0743331 A JP H0743331A JP 20350793 A JP20350793 A JP 20350793A JP 20350793 A JP20350793 A JP 20350793A JP H0743331 A JPH0743331 A JP H0743331A
- Authority
- JP
- Japan
- Prior art keywords
- metal oxide
- gas sensor
- thick film
- layer
- gas
- 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.)
- Pending
Links
Landscapes
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明はＬＰガス，都市ガス，
水素ガス等を検出するガス漏れ警報器用の厚膜ガスセン
サに係り、特に感ガス層の構成に関する。BACKGROUND OF THE INVENTION This invention relates to LP gas, city gas,
The present invention relates to a thick film gas sensor for a gas leak alarm that detects hydrogen gas and the like, and more particularly to the structure of a gas sensitive layer.
【０００２】[0002]
【従来の技術】ガスセンサの一つとして酸化スズや酸化
亜鉛等の金属酸化物半導体を用いるものが知られてい
る。これら金属酸化物半導体は大気中において３００な
いし５００℃程度に加熱されると粒子表面に大気中の酸
素が活性化吸着し、高抵抗化するが還元性ガスである被
検ガス中では還元性ガスが吸着酸素に替えて金属酸化物
半導体に吸着され電気抵抗値が減少する。このような性
質を利用して金属酸化物半導体を利用するガスセンサが
ＬＰガスや都市ガス等のガス漏れ警報器用に利用されて
いる。2. Description of the Related Art As one of gas sensors, one using a metal oxide semiconductor such as tin oxide or zinc oxide is known. When these metal oxide semiconductors are heated to about 300 to 500 ° C. in the atmosphere, oxygen in the atmosphere is activated and adsorbed on the particle surface to increase the resistance, but the reducing gas is a reducing gas in the test gas which is a reducing gas. Is adsorbed on the metal oxide semiconductor instead of adsorbed oxygen, and the electric resistance value is reduced. A gas sensor using a metal oxide semiconductor by utilizing such a property is used for a gas leak alarm device for LP gas, city gas, or the like.
【０００３】図１３は従来の厚膜ガスセンサを示す平面
図である。図１４は従来の厚膜ガスセンサを示す図１３
のＣ−Ｃ矢視断面図である。従来の厚膜ガスセンサはア
ルミナ等の絶縁性基板１の一主面上に感ガス層４と酸化
燃焼層３を積層して形成される。基板１の他の主面には
ヒータ８が形成され厚膜ガスセンサを所定の温度に加熱
する。感ガス層４は例えば酸化スズからなる層である。
酸化燃焼層３は酸化スズに白金のような貴金属触媒を担
持して形成される。この酸化燃焼層３は感ガス層４の可
燃性ガス中における抵抗値の経時的な安定性を高めると
ともに、可燃性ガスに対する選択性を高めてアルコール
等に対する感度を低減させる。感ガス層４またはヒータ
８には電極２，２Ａを介して商用電源が直接的に印加さ
れる。FIG. 13 is a plan view showing a conventional thick film gas sensor. FIG. 14 shows a conventional thick film gas sensor.
FIG. 9 is a cross-sectional view taken along line C-C of FIG. A conventional thick film gas sensor is formed by laminating a gas sensitive layer 4 and an oxidative combustion layer 3 on one main surface of an insulating substrate 1 made of alumina or the like. A heater 8 is formed on the other main surface of the substrate 1 to heat the thick film gas sensor to a predetermined temperature. The gas sensitive layer 4 is a layer made of tin oxide, for example.
The oxidation combustion layer 3 is formed by supporting a noble metal catalyst such as platinum on tin oxide. The oxidizing combustion layer 3 enhances the stability of the resistance value of the gas sensitive layer 4 in the combustible gas over time, and enhances the selectivity for the combustible gas to reduce the sensitivity to alcohol and the like. A commercial power source is directly applied to the gas sensitive layer 4 or the heater 8 via the electrodes 2 and 2A.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら上述のよ
うな従来の二層型厚膜ガスセンサにおいては検知ガス中
におけるセンサ抵抗値の経時的安定性は良好であるが、
初期鳴動時間が長いという問題があった。従来の初期鳴
動時間は約２分であった。図１２は従来の厚膜ガスセン
サの初期鳴動特性を示す線図である。However, in the conventional double-layer thick film gas sensor as described above, the stability of the sensor resistance value in the detection gas over time is good, but
There was a problem that the initial ringing time was long. The conventional initial ringing time was about 2 minutes. FIG. 12 is a diagram showing an initial ringing characteristic of a conventional thick film gas sensor.
【０００５】この初期鳴動はガスセンサに電源を投入し
てガスセンサの使用を開始したときにセンサの抵抗が一
旦減少してから上昇するために抵抗の減少している間は
警報を発することとなり初期鳴動時間はその警報を発し
ている時間を指す。従ってこの鳴動時間中はガスセンサ
が警報を発しないように制御するがこの初期鳴動時間が
長くなるとガスセンサの使用開始に手間取り好ましくな
いのである。二層型の厚膜ガスセンサにおいて初期鳴動
時間が長くなる原因は電源投入後に感ガス層の金属酸化
物半導体が酸素を吸着して電気抵抗値を増大するがこの
酸素吸着に時間がかかるためである。従って酸素吸着速
度を増大させる貴金属のような触媒を感ガス層の金属酸
化物半導体に直接担持すればよいが貴金属触媒を酸化ス
ズのような金属酸化物半導体に直接的に担持すると貴金
属触媒が熱的に粒成長を起こし、そのために貴金属触媒
の活性度が低下して金属酸化物半導体の酸素吸着量が減
少し経時的に厚膜ガスセンサの電気抵抗値が低下する。This initial ringing causes an alarm to be issued while the resistance is decreasing because the resistance of the gas sensor once decreases and then rises when the gas sensor is powered on and the gas sensor is started to be used. Time refers to the time when the alarm is issued. Therefore, during this ringing time, the gas sensor is controlled so as not to give an alarm, but if this initial ringing time becomes long, it is not preferable to start using the gas sensor. In the double-layer thick-film gas sensor, the reason why the initial ringing time is long is that the metal oxide semiconductor in the gas-sensitive layer adsorbs oxygen to increase the electric resistance value after the power is turned on, but this oxygen adsorption takes time. . Therefore, a catalyst such as a noble metal that increases the oxygen adsorption rate may be directly supported on the metal oxide semiconductor of the gas-sensitive layer, but if the noble metal catalyst is directly supported on the metal oxide semiconductor such as tin oxide, the noble metal catalyst is heated. Grain growth occurs, which reduces the activity of the noble metal catalyst, reduces the amount of oxygen adsorbed by the metal oxide semiconductor, and decreases the electrical resistance value of the thick film gas sensor over time.
【０００６】この発明は上述の点に鑑みてなされ、その
目的は金属酸化物半導体の抵抗値は変動させないが酸素
吸着速度は増大させるようにして抵抗値の経時的安定性
と初期鳴動特性に優れる厚膜ガスセンサを提供すること
にある。The present invention has been made in view of the above points, and an object thereof is not to change the resistance value of a metal oxide semiconductor, but to increase the oxygen adsorption rate so that the stability of the resistance value with time and the initial ringing characteristic are excellent. It is to provide a thick film gas sensor.
【０００７】[0007]
【課題を解決するための手段】上述の目的は第一の発明
によれば金属酸化物半導体の抵抗値の変化を利用してガ
スの有無を検出する厚膜ガスセンサであって、基板と、
一対の電極と、第一の酸化燃焼層と、感ガス層とを包含
し、基板はガスセンサの支持体であり、一対の電極は基
板上に離間して直接的に被着され、感ガス層は基板と一
対の電極上に選択的に積層され、第一の酸化燃焼層は感
ガス層の全部を被覆して積層され、感ガス層は第一の貴
金属触媒を担持した比表面積の大きな第一の金属酸化物
を金属酸化物半導体に含有してなり、第一の酸化燃焼層
は第二の貴金属触媒を第二の金属酸化物に担持してなる
とすることにより達成される。According to the first aspect of the present invention, there is provided a thick film gas sensor for detecting the presence or absence of gas by utilizing a change in resistance value of a metal oxide semiconductor.
A pair of electrodes, a first oxidative combustion layer, and a gas sensitive layer are included, the substrate is a support of the gas sensor, and the pair of electrodes are directly and separately spaced on the substrate to form a gas sensitive layer. Is selectively laminated on the substrate and a pair of electrodes, the first oxidative combustion layer is laminated so as to cover the entire gas-sensitive layer, and the gas-sensitive layer is the first noble metal catalyst supporting a large specific surface area. This is achieved by containing one metal oxide in a metal oxide semiconductor, and forming the first oxidation combustion layer by supporting the second noble metal catalyst on the second metal oxide.
【０００８】また第二の発明によれば金属酸化物半導体
の抵抗値の変化を利用してガスの有無を検出する厚膜ガ
スセンサであって、基板と、一対の電極と、第二の酸化
燃焼層と、感ガス層と、第三の酸化燃焼層とを包含し、
基板はガスセンサの支持体であり、一対の電極は基板上
に離間して直接的に被着され、第二の酸化燃焼層は基板
と一対の電極上に選択的に積層され、感ガス層は第二の
酸化燃焼層と一対の電極上に選択的に積層され、第三の
酸化燃焼層は感ガス層の全部を被覆して積層され、感ガ
ス層は第一の貴金属触媒を担持した比表面積の大きな第
一の金属酸化物を金属酸化物半導体に含有してなり、第
二の酸化燃焼層は第二の貴金属触媒を第二の金属酸化物
に担持してなり、第三の酸化燃焼層は第二の貴金属触媒
を第二の金属酸化物に担持してなるとすることにより達
成される。According to a second aspect of the present invention, there is provided a thick film gas sensor for detecting the presence / absence of gas by utilizing a change in resistance value of a metal oxide semiconductor, the substrate, a pair of electrodes, and a second oxidative combustion. Including a layer, a gas-sensitive layer, and a third oxidative combustion layer,
The substrate is a support for the gas sensor, the pair of electrodes is directly spaced apart on the substrate, the second oxidation combustion layer is selectively laminated on the substrate and the pair of electrodes, and the gas-sensitive layer is The second oxidative combustion layer is selectively laminated on the pair of electrodes, the third oxidative combustion layer is laminated so as to cover the entire gas-sensitive layer, and the gas-sensitive layer is a ratio supporting the first noble metal catalyst. The first metal oxide having a large surface area is contained in the metal oxide semiconductor, the second oxidation combustion layer is formed by supporting the second noble metal catalyst on the second metal oxide, and the third oxidation combustion layer is formed. The layer is achieved by providing a second noble metal catalyst on a second metal oxide.
【０００９】さらに第三の発明によれば金属酸化物半導
体の抵抗値の変化を利用してガスの有無を検出する厚膜
ガスセンサであって、（１）基板と、（２）一対の電極
と、（３）第二の酸化燃焼層と、（４）感ガス層と、
（３）第三の酸化燃焼層とを包含し、基板はガスセンサ
の支持体であり、一対の電極は基板上に離間して直接的
に被着され、第二の酸化燃焼層は基板と一対の電極上に
選択的に積層され、感ガス層は第二の酸化燃焼層と一対
の電極上に選択的に積層され、第三の酸化燃焼層は感ガ
ス層の全部を被覆して積層され、感ガス層は金属酸化物
半導体からなり、第二の酸化燃焼層は貴金属触媒を第三
の金属酸化物に担持してなり、第三の酸化燃焼層は貴金
属触媒を第三の金属酸化物に担持してなるとすることに
より達成される。According to a third aspect of the present invention, there is provided a thick film gas sensor for detecting the presence or absence of gas by utilizing the change in the resistance value of a metal oxide semiconductor, which comprises (1) a substrate and (2) a pair of electrodes. , (3) second oxidative combustion layer, (4) gas sensitive layer,
(3) Including a third oxidative combustion layer, the substrate is a support of the gas sensor, the pair of electrodes are directly spaced apart and directly applied on the substrate, and the second oxidative combustion layer is paired with the substrate. , The gas-sensitive layer is selectively laminated on the second oxidation combustion layer and the pair of electrodes, and the third oxidation-combustion layer is laminated to cover the entire gas-sensing layer. , The gas-sensitive layer is made of a metal oxide semiconductor, the second oxidation combustion layer has a noble metal catalyst supported on a third metal oxide, and the third oxidation combustion layer has a noble metal catalyst made of a third metal oxide. It is achieved by carrying the above.
【００１０】活性アルミナ，活性シリカ，活性シリカア
ルミナは比表面積が大きくそれぞれ例えば１００ないし
２００m2/g、３００ないし６００m2/g、３００ないし６
００m2/g程度のものを指す。Activated alumina, activated silica, and activated silica-alumina have large specific surface areas, for example, 100 to 200 m 2 / g, 300 to 600 m 2 / g, 300 to 6 respectively.
It is about 00 m 2 / g.
【００１１】[0011]
【作用】比表面積の大きな第一の金属酸化物は貴金属触
媒を担持したときに貴金属触媒が粒成長をおこすことが
なく触媒活性が長期に維持される。酸素が感ガス層に化
学吸着する速度は酸素の拡散速度に支配されるが、感光
層の厚さｄを拡散距離と考えると、拡散距離ｄは拡散定
数をＤ、拡散時間をｔとして次式で与えられる。[Function] The first metal oxide having a large specific surface area does not cause particle growth of the noble metal catalyst when the noble metal catalyst is supported, and the catalytic activity is maintained for a long time. The rate at which oxygen is chemically adsorbed in the gas sensitive layer is governed by the oxygen diffusion rate. Considering the thickness d of the photosensitive layer as the diffusion distance, the diffusion distance d is expressed by Given in.
【００１２】[0012]
【数１】 ｄ＝２×（Ｄｔ）1/2 （１） 初期鳴動時間は（１）式の拡散時間ｔに比例するから
（２）式が与えられる。## EQU1 ## d = 2 × (Dt) 1/2 (1) Since the initial ringing time is proportional to the diffusion time t of the equation (1), the equation (2) is given.
【００１３】[0013]
【数２】 初期鳴動時間∝ｔ＝ｄ2 ／４Ｄ （２） 感ガス層を第二と第三の酸化燃焼層で挟むときは酸素は
第二と第三の酸化燃焼層から供給され感ガス層の厚さは
実質的に１／２となるから（２）式により初期鳴動時間
は１／４となる。[Equation 2] Initial ringing time ∝t = d 2 / 4D (2) When the gas-sensitive layer is sandwiched between the second and third oxidation combustion layers, oxygen is supplied from the second and third oxidation combustion layers. Since the layer thickness is substantially 1/2, the initial ringing time is 1/4 according to the equation (2).
【００１４】[0014]
【実施例】次にこの発明の実施例を図面に基づいて説明
する。 実施例１ 図１は第一の発明の実施例に係る厚膜ガスセンサを示す
平面図である。図２は第一の発明の実施例に係る厚膜ガ
スセンサを示す図１のＡ−Ａ矢視断面図である。Embodiments of the present invention will now be described with reference to the drawings. Embodiment 1 FIG. 1 is a plan view showing a thick film gas sensor according to an embodiment of the first invention. 2 is a sectional view taken along the line AA of FIG. 1 showing a thick film gas sensor according to an embodiment of the first invention.
【００１５】この発明の実施例に係る厚膜ガスセンサの
構造は次の通りである。基板１の一主面上に離間して二
つの電極２が設けられる。基板１と電極２の上に感ガス
層４が選択的に形成される。感ガス層４を完全に被覆し
て第一の酸化燃焼層３Ａが設けられる。電極２にリード
線７が接続される。基板１の他の主面には電極２Ａが形
成され、電極２Ａと基板１の上に選択的にヒータ８が形
成され、電極２Ａにはリード線９が接続される。The structure of the thick film gas sensor according to the embodiment of the present invention is as follows. Two electrodes 2 are provided on one main surface of the substrate 1 at a distance from each other. The gas sensitive layer 4 is selectively formed on the substrate 1 and the electrode 2. A first oxidation combustion layer 3A is provided by completely covering the gas sensitive layer 4. The lead wire 7 is connected to the electrode 2. An electrode 2A is formed on the other main surface of the substrate 1, a heater 8 is selectively formed on the electrode 2A and the substrate 1, and a lead wire 9 is connected to the electrode 2A.
【００１６】基板１は厚さ０．５ｍｍで縦３ｍｍ、横３
ｍｍの研磨されたアルミナ基板である。ヒータは酸化ル
テニウム抵抗体からなる。このような厚膜ガスセンサは
次のようにして調製される。基板１の二つの主面に白金
電極ペーストを所定のパターンでスクリーン印刷し、乾
燥後約１１００℃の温度で焼成した。酸化ルテニウムか
らなるヒータ用ペーストを所定のパターンでスクリーン
印刷し所定の温度で焼成した。The substrate 1 has a thickness of 0.5 mm and a length of 3 mm and a width of 3 mm.
mm polished alumina substrate. The heater comprises a ruthenium oxide resistor. Such a thick film gas sensor is prepared as follows. A platinum electrode paste was screen-printed on the two main surfaces of the substrate 1 in a predetermined pattern, dried, and then baked at a temperature of about 1100 ° C. A heater paste made of ruthenium oxide was screen-printed in a predetermined pattern and fired at a predetermined temperature.
【００１７】中心粒径４μｍ，比表面積が１２０m2/gの
γ−アルミナ粉体に塩化パラジウム水溶液を含浸し、乾
燥後６００℃の温度で３ｈ熱処理してγ−アルミナ粉体
にパラジウPdを５重量％の割合で担持した。中心粒径が
２μｍの酸化スズ粉体を乾燥空気中で温度７３０℃で２
ｈ処理し、得られた酸化スズ粉体に前記パラジウPd付き
γ−アルミナ粉体を酸化スズ粉体に対しアルミナとして
４重量％の割合で添加した。エタノールを分散媒として
湿式混合し、３００℃の温度で３ｈ乾燥してエタノール
を完全に除去した。A γ-alumina powder having a central particle size of 4 μm and a specific surface area of 120 m 2 / g was impregnated with an aqueous palladium chloride solution, dried and then heat-treated at a temperature of 600 ° C. for 3 hours to give γ-alumina powder containing 5 parts of palladium Pd. The loading was carried out at a weight percentage. 2 tin oxide powder with a median particle size of 2 μm in dry air at a temperature of 730 ° C
The γ-alumina powder with palladium (Pd) was added to the tin oxide powder obtained by the h treatment at a ratio of 4% by weight as alumina to the tin oxide powder. Wet mixing was performed using ethanol as a dispersion medium, and the mixture was dried at a temperature of 300 ° C. for 3 hours to completely remove ethanol.
【００１８】得られた混合粉体にエチルシリケート、エ
チルセルロース、カルビトール等を適量加え混練して粘
度が３００ないし４００ポイズの感ガス層用ペーストを
得た。得られたペーストを所定のパターンによりスクリ
ーン印刷し、１２０℃で２ｈ乾燥した。中心粒径４μ
ｍ，比表面積が１２０m2/gのγ−アルミナ粉体に塩化白
金酸H2PtCl6 水溶液を加え、乾燥後６００℃の温度で３
ｈ熱処理してγ−アルミナ粉体に３重量％の割合で白金
を担持した。白金の担持されたγ−アルミナ粉体をボー
ルミルで粉砕したのち、エチルシリケート，エチルセル
ロース，カルビトール等を適量加え、混練して粘度が３
００ないし４００ポイズの第一の酸化燃焼層用のペース
トを得た。得られた酸化燃焼層用のペーストを所定のパ
ターンによりスクリーン印刷し、１２０℃で２ｈ乾燥し
た。An appropriate amount of ethyl silicate, ethyl cellulose, carbitol and the like was added to the obtained mixed powder and kneaded to obtain a gas sensitive layer paste having a viscosity of 300 to 400 poise. The obtained paste was screen-printed with a predetermined pattern and dried at 120 ° C. for 2 hours. Central particle size 4μ
m, a specific surface area of 120 m 2 / g to γ-alumina powder, chloroplatinic acid H 2 PtCl 6 aqueous solution was added, and dried at 600 ° C. for 3
h Heat treatment was carried out to support 3% by weight of platinum on the γ-alumina powder. Platinum-supported γ-alumina powder was crushed with a ball mill, and then an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a viscosity of 3
A paste for the first oxidative combustion layer of 00 to 400 poise was obtained. The obtained paste for oxidative combustion layer was screen-printed with a predetermined pattern and dried at 120 ° C. for 2 hours.
【００１９】感ガス層と第一の酸化燃焼層を印刷し乾燥
した後にこれらを６３０℃の温度で３ｈ同時に焼成して
感ガス層４、第一の酸化燃焼層３Ａを形成した。焼成後
の感ガス層と第一の酸化燃焼層の厚さはそれぞれ２０μ
ｍと５０μｍであった。第一の酸化燃焼層はプロパン，
メタン等の厚膜ガスセンサの検知対象ガスに対する干渉
ガスであるアルコールガス等による誤報を防止する。ア
ルコールガス等は貴金属触媒により容易に酸化されやす
く第一の酸化燃焼層３Ａにより選択的に燃焼させること
ができる。After the gas-sensitive layer and the first oxidative combustion layer were printed and dried, they were simultaneously fired at a temperature of 630 ° C. for 3 hours to form a gas-sensitive layer 4 and a first oxidative combustion layer 3A. The thickness of the gas sensitive layer and the first oxidative combustion layer after firing are each 20μ.
m and 50 μm. The first oxidation combustion layer is propane,
Prevents false alarms due to alcohol gas, which is an interference gas with respect to the gas to be detected by a thick film gas sensor such as methane. Alcohol gas or the like is easily oxidized by the noble metal catalyst and can be selectively burned by the first oxidation combustion layer 3A.
【００２０】続いて電極２，２Ａにそれぞれ白金リード
線７，９を接続して厚膜ガスセンサを得た。それぞれの
リード線を警報器の回路に接続した。 比較例１ 実施例と同一の構造の厚膜ガスセンサを用いた。このよ
うな厚膜ガスセンサは次のようにして調製される。基板
１の二つの主面に白金電極ペーストを所定のパターンで
スクリーン印刷し、乾燥後約１１００℃の温度で焼成し
た。酸化ルテニウムからなるヒータ用ペーストを所定の
パターンでスクリーン印刷し所定の温度で焼成した。Subsequently, platinum lead wires 7 and 9 were respectively connected to the electrodes 2 and 2A to obtain a thick film gas sensor. Each lead wire was connected to the alarm circuit. Comparative Example 1 A thick film gas sensor having the same structure as that of the example was used. Such a thick film gas sensor is prepared as follows. A platinum electrode paste was screen-printed on the two main surfaces of the substrate 1 in a predetermined pattern, dried, and then baked at a temperature of about 1100 ° C. A heater paste made of ruthenium oxide was screen-printed in a predetermined pattern and fired at a predetermined temperature.
【００２１】酸化スズ粉体を乾燥空気中で温度７３０℃
で２ｈ処理し、得られた酸化スズ粉体に塩化パラジウム
水溶液を含浸し混練したのち乾燥した。この粉体を温度
６００℃で３ｈ熱処理し、塩化パラジウムを分解して酸
化スズ粉体上にパラジウムPdを２重量％の割合で担持し
た。得られた粉体をボールミルで粉砕したのち、エチル
シリケート、エチルセルロース、カルビトール等を適量
加え、混練して感ガス層用のペーストを得た。得られた
感ガス層用のペーストを所定のパターンによりスクリー
ン印刷し、１２０℃で２ｈ乾燥した。The tin oxide powder is dried in air at a temperature of 730 ° C.
The obtained tin oxide powder was impregnated with an aqueous solution of palladium chloride, kneaded, and then dried. This powder was heat-treated at a temperature of 600 ° C. for 3 hours to decompose the palladium chloride and carry 2% by weight of palladium Pd on the tin oxide powder. The obtained powder was pulverized with a ball mill, and then an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a gas-sensitive layer paste. The obtained gas-sensitive layer paste was screen-printed in a predetermined pattern and dried at 120 ° C. for 2 hours.
【００２２】中心粒径４μｍ，比表面積が１２０m2/gの
γ−アルミナ粉体に塩化白金酸H2PtCl6 水溶液を加え、
乾燥後６００℃の温度で３ｈ熱処理してγ−アルミナ粉
体に３重量％の割合で白金を担持した。白金の担持され
たγ−アルミナ粉体をボールミルで粉砕したのち、エチ
ルシリケート，エチルセルロース，カルビトール等を適
量加え、混練して粘度が３００ないし４００ポイズの第
一の酸化燃焼層用のペーストを得た。得られた第一の酸
化燃焼層用のペーストを所定のパターンによりスクリー
ン印刷し、１２０℃で２ｈ乾燥した。A chloroplatinic acid H 2 PtCl 6 aqueous solution was added to γ-alumina powder having a central particle size of 4 μm and a specific surface area of 120 m 2 / g,
After drying, the γ-alumina powder was heat-treated at 600 ° C. for 3 hours to support platinum at a ratio of 3% by weight. Platinum-supported γ-alumina powder was crushed with a ball mill, and then an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a paste for the first oxidative combustion layer having a viscosity of 300 to 400 poise. It was The obtained paste for the first oxidation combustion layer was screen-printed in a predetermined pattern and dried at 120 ° C. for 2 hours.
【００２３】感ガス層と第一の酸化燃焼層を印刷し乾燥
した後にこれらを６３０℃の温度で３ｈ同時に焼成して
感ガス層４、第一の酸化燃焼層３Ａを形成した。焼成後
の感ガス層と酸化燃焼層の厚さはそれぞれ２０μｍと５
０μｍであった。図７は実施例１の厚膜ガスセンサの抵
抗値につきその経時特性（イ）を比較例１に係る厚膜ガ
スセンサの特性（ロ）と対比して示す線図である。比較
例１に係る厚膜ガスセンサは触媒が粒成長して抵抗値が
経時的に変化するが実施例１に係る厚膜ガスセンサの抵
抗値は経時的に安定であるこがわかる。After the gas-sensitive layer and the first oxidative combustion layer were printed and dried, they were simultaneously fired at a temperature of 630 ° C. for 3 hours to form a gas-sensitive layer 4 and a first oxidative combustion layer 3A. The thickness of the gas sensitive layer and the oxidative combustion layer after firing are 20 μm and 5 respectively.
It was 0 μm. FIG. 7 is a diagram showing the time-dependent characteristic (a) of the resistance value of the thick film gas sensor of Example 1 in comparison with the characteristic (b) of the thick film gas sensor according to Comparative Example 1. It can be seen that in the thick film gas sensor according to Comparative Example 1, the catalyst particles grow and the resistance value changes with time, but the resistance value of the thick film gas sensor according to Example 1 is stable with time.
【００２４】また実施例１に係る厚膜ガスセンサの初期
鳴動時間は約１分であり、従来の１／２になっている。
上述の例では金属酸化物半導体に酸化スズを用いている
が酸化スズに替えて酸化亜鉛を用いることもできる。ま
た上述の例では第一の金属酸化物に活性アルミナを用い
ているが活性アルミナに替えて活性シリカや活性シリカ
アルミナを用いることもできる。The initial ringing time of the thick film gas sensor according to the first embodiment is about 1 minute, which is half that of the conventional one.
Although tin oxide is used for the metal oxide semiconductor in the above example, zinc oxide may be used instead of tin oxide. In the above example, activated alumina is used as the first metal oxide, but activated silica or activated silica alumina can be used instead of activated alumina.
【００２５】さらに上述の例では第一の貴金属触媒にパ
ラジウムを用いているがパラジウムに替えて白金または
パラジウムと白金の混合物を用いることもできる。さら
に上述の例では第二の貴金属触媒に白金を用いているが
白金に替えてパラジウムまたはパラジウムと白金の混合
物を用いることもできる。第一の金属酸化物に対する第
一の貴金属触媒の担持量は第一の貴金属触媒が粒成長を
起こさない範囲に選んだ。例えばγ−アルミナにパラジ
ウムを担持する場合はパラジウムが３ないし１５重量％
の範囲内で粒成長が回避された。他の第一の金属酸化物
と第一の貴金属触媒の組み合わせに関しても同様であっ
た。Further, although palladium is used as the first noble metal catalyst in the above example, platinum or a mixture of palladium and platinum may be used instead of palladium. Furthermore, although platinum is used as the second noble metal catalyst in the above example, palladium or a mixture of palladium and platinum can be used instead of platinum. The amount of the first noble metal catalyst supported on the first metal oxide was selected within a range in which the first noble metal catalyst did not cause grain growth. For example, when palladium is supported on γ-alumina, the palladium content is 3 to 15% by weight.
Grain growth was avoided within the range of. The same was true for other combinations of the first metal oxide and the first noble metal catalyst.
【００２６】第一の貴金属触媒を担持した第一の金属酸
化物の金属酸化物半導体に対する添加量は抵抗値の経時
変化が起こらずまた抵抗値の絶対値が適当な値になる範
囲に選んだ。例えば５重量％のパラジウムを担持したγ
−アルミナを酸化スズに添加した場合の０．２％イソブ
タンガス中の抵抗値の経時変化が表１に示される。The addition amount of the first metal oxide carrying the first noble metal catalyst to the metal oxide semiconductor is selected in such a range that the resistance value does not change with time and the absolute value of the resistance value becomes an appropriate value. . For example, γ supporting 5% by weight of palladium
Table 1 shows the change with time of the resistance value in 0.2% isobutane gas when alumina is added to tin oxide.
【００２７】[0027]
【表１】 添加量が３％より少ないと、抵抗値の経時的変化が起こ
る。また１０％を越えると、抵抗値の絶対値が大き過ぎ
る。 実施例２ 図３は第二の発明の実施例に係る厚膜ガスセンサを示す
平面図である。[Table 1] If the added amount is less than 3%, the resistance value changes with time. If it exceeds 10%, the absolute value of the resistance is too large. Embodiment 2 FIG. 3 is a plan view showing a thick film gas sensor according to an embodiment of the second invention.
【００２８】図４は第二の発明の実施例に係る厚膜ガス
センサを示す図３のＤ−Ｄ矢視断面図である。第二の発
明の実施例に係る厚膜ガスセンサの構造は次の通りであ
る。基板１の一主面上に離間して二つの電極２が設けら
れる。基板１と電極２の上に第二の酸化燃焼層３Ｂが選
択的に形成される。感ガス層４が第二の酸化燃焼層３Ｂ
と一対の電極の上に選択的に設けられる。第三の酸化燃
焼層３Ｃが感ガス層４を完全に被覆して積層される。電
極２にリード線７が接続される。基板１の他の主面には
電極２Ａが形成され、電極２Ａと基板１の上に選択的に
ヒータ８が形成され、電極２Ａにはリード線９が接続さ
れる。FIG. 4 is a sectional view taken along the line DD of FIG. 3 showing a thick film gas sensor according to an embodiment of the second invention. The structure of the thick film gas sensor according to the embodiment of the second invention is as follows. Two electrodes 2 are provided on one main surface of the substrate 1 at a distance from each other. The second oxidative combustion layer 3B is selectively formed on the substrate 1 and the electrode 2. The gas sensitive layer 4 is the second oxidation combustion layer 3B.
And selectively provided on the pair of electrodes. The third oxidative combustion layer 3C is laminated so as to completely cover the gas sensitive layer 4. The lead wire 7 is connected to the electrode 2. An electrode 2A is formed on the other main surface of the substrate 1, a heater 8 is selectively formed on the electrode 2A and the substrate 1, and a lead wire 9 is connected to the electrode 2A.
【００２９】基板１は厚さ０．５ｍｍで縦３ｍｍ、横３
ｍｍの研磨されたアルミナ基板である。ヒータは酸化ル
テニウム抵抗体からなる。このような厚膜ガスセンサは
次のようにして調製される。基板１の二つの主面に白金
電極ペーストを所定のパターンでスクリーン印刷し、乾
燥後約１１００℃の温度で焼成した。酸化ルテニウムか
らなるヒータ用ペーストを所定のパターンでスクリーン
印刷し所定の温度で焼成した。The substrate 1 has a thickness of 0.5 mm and a length of 3 mm and a width of 3
mm polished alumina substrate. The heater comprises a ruthenium oxide resistor. Such a thick film gas sensor is prepared as follows. A platinum electrode paste was screen-printed on the two main surfaces of the substrate 1 in a predetermined pattern, dried, and then baked at a temperature of about 1100 ° C. A heater paste made of ruthenium oxide was screen-printed in a predetermined pattern and fired at a predetermined temperature.
【００３０】中心粒径４μｍ，比表面積が１２０m2/gの
γ−アルミナ粉体に塩化白金酸H2PtCl6 水溶液を加え、
乾燥後６００℃の温度で３ｈ熱処理してγ−アルミナ粉
体に３重量％の割合で白金を担持した。白金の担持され
たγ−アルミナ粉体をボールミルで粉砕したのち、エチ
ルシリケート，エチルセルロース，カルビトール等を適
量加え、混練して粘度が３００ないし４００ポイズの第
二の酸化燃焼層用のペーストを得た。得られた第二の酸
化燃焼層用のペーストを所定のパターンによりスクリー
ン印刷し、１２０℃で２ｈ乾燥した。A chloroplatinic acid H 2 PtCl 6 aqueous solution was added to γ-alumina powder having a central particle size of 4 μm and a specific surface area of 120 m 2 / g.
After drying, the γ-alumina powder was heat-treated at 600 ° C. for 3 hours to support platinum at a ratio of 3% by weight. Platinum-supported γ-alumina powder was crushed with a ball mill, and then an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a paste for the second oxidative combustion layer having a viscosity of 300 to 400 poise. It was The obtained paste for the second oxidation combustion layer was screen-printed in a predetermined pattern and dried at 120 ° C. for 2 hours.
【００３１】中心粒径４μｍ，比表面積が１２０m2/gの
γ−アルミナ粉体に塩化パラジウム水溶液を含浸し、乾
燥後６００℃の温度で３ｈ熱処理してγ−アルミナ粉体
にパラジウPdを５重量％の割合で担持した。中心粒径が
２μｍの酸化スズ粉体を乾燥空気中で温度７３０℃で２
ｈ処理し、得られた酸化スズ粉体に前記パラジウPd付き
γ−アルミナ粉体を酸化スズ粉体に対しアルミナとして
４重量％の割合で添加した。エタノールを分散媒として
湿式混合し、３００℃の温度で３ｈ乾燥してエタノール
を完全に除去した。A γ-alumina powder having a central particle diameter of 4 μm and a specific surface area of 120 m 2 / g was impregnated with an aqueous palladium chloride solution, dried, and then heat-treated at a temperature of 600 ° C. for 3 hours to add 5 parts of palladium Pd to the γ-alumina powder. The loading was carried out at a weight percentage. 2 tin oxide powder with a median particle size of 2 μm in dry air at a temperature of 730 ° C
The γ-alumina powder with palladium (Pd) was added to the tin oxide powder obtained by the h treatment at a ratio of 4% by weight as alumina to the tin oxide powder. Wet mixing was performed using ethanol as a dispersion medium, and the mixture was dried at a temperature of 300 ° C. for 3 hours to completely remove ethanol.
【００３２】得られた混合粉体にエチルシリケート、エ
チルセルロース、カルビトール等を適量加え混練して粘
度が３００ないし４００ポイズの感ガス層用ペーストを
得た。得られたペーストを所定のパターンによりスクリ
ーン印刷し、１２０℃で２ｈ乾燥した。中心粒径４μ
ｍ，比表面積が１２０m2/gのγ−アルミナ粉体に塩化白
金酸H2PtCl6 水溶液を加え、乾燥後６００℃の温度で３
ｈ熱処理してγ−アルミナ粉体に３重量％の割合で白金
を担持した。白金の担持されたγ−アルミナ粉体をボー
ルミルで粉砕したのち、エチルシリケート，エチルセル
ロース，カルビトール等を適量加え、混練して粘度が３
００ないし４００ポイズの第三の酸化燃焼層用のペース
トを得た。得られた第三の酸化燃焼層用のペーストを所
定のパターンによりスクリーン印刷し、１２０℃で２ｈ
乾燥した。An appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added to the obtained mixed powder and kneaded to obtain a gas-sensitive layer paste having a viscosity of 300 to 400 poise. The obtained paste was screen-printed with a predetermined pattern and dried at 120 ° C. for 2 hours. Central particle size 4μ
m, a specific surface area of 120 m 2 / g to γ-alumina powder, chloroplatinic acid H 2 PtCl 6 aqueous solution was added, and after drying at a temperature of 600 ° C. 3
h Heat treatment was carried out to support 3% by weight of platinum on the γ-alumina powder. Platinum-supported γ-alumina powder was crushed with a ball mill, and then an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a viscosity of 3
A paste for the third oxidative combustion layer of 00 to 400 poise was obtained. The obtained paste for the third oxidation combustion layer is screen-printed in a predetermined pattern, and it is heated at 120 ° C. for 2 hours.
Dried.
【００３３】感ガス層と第二の酸化燃焼層と第三の酸化
燃焼層を印刷し乾燥した後にこれらを６３０℃の温度で
３ｈ同時に焼成して感ガス層４、第二の酸化燃焼層３
Ｂ、第三の酸化燃焼層３Ｃを形成した。焼成後の感ガス
層４と第二の酸化燃焼層３Ｂと第三の酸化燃焼層３Ｃの
厚さはそれぞれ２０μｍ、５０μｍ、５０μｍであっ
た。The gas-sensitive layer, the second oxidation-combustion layer and the third oxidation-combustion layer are printed and dried, and then these are simultaneously fired at a temperature of 630 ° C. for 3 hours to form the gas-sensing layer 4 and the second oxidation-combustion layer 3.
B, the third oxidation combustion layer 3C was formed. The thicknesses of the gas sensitive layer 4, the second oxidative combustion layer 3B and the third oxidative combustion layer 3C after firing were 20 μm, 50 μm and 50 μm, respectively.
【００３４】第二の酸化燃焼層、第三の酸化燃焼層はプ
ロパン，メタン等の厚膜ガスセンサの検知対象ガスに対
する干渉ガスであるアルコールガス等による誤報を防止
する。アルコールガス等は貴金属触媒により容易に酸化
されやすく第二の酸化燃焼層と第三の酸化燃焼層により
選択的に燃焼させることができる。さらに第二の酸化燃
焼層と第三の酸化燃焼層は共同して酸素の供給速度を高
めて、初期鳴動時間を短くすることができる。The second oxidative combustion layer and the third oxidative combustion layer prevent false alarms due to alcohol gas or the like which is an interference gas with respect to the gas to be detected by the thick film gas sensor such as propane and methane. Alcohol gas is easily oxidized by the noble metal catalyst and can be selectively burned by the second oxidation combustion layer and the third oxidation combustion layer. Furthermore, the second oxidizing combustion layer and the third oxidizing combustion layer can cooperate to increase the oxygen supply rate and shorten the initial ringing time.
【００３５】続いて電極２，２Ａにそれぞれ白金リード
線７，９を接続して厚膜ガスセンサを得た。それぞれの
リード線を警報器の回路に接続した。 比較例２ 実施例２と同一の構造の厚膜ガスセンサを用いた。この
ような厚膜ガスセンサは次のようにして調製される。Subsequently, platinum lead wires 7 and 9 were respectively connected to the electrodes 2 and 2A to obtain a thick film gas sensor. Each lead wire was connected to the alarm circuit. Comparative Example 2 A thick film gas sensor having the same structure as in Example 2 was used. Such a thick film gas sensor is prepared as follows.
【００３６】基板１の二つの主面に白金電極ペーストを
所定のパターンでスクリーン印刷し、乾燥後約１１００
℃の温度で焼成した。酸化ルテニウムからなるヒータ用
ペーストを所定のパターンでスクリーン印刷し所定の温
度で焼成した。中心粒径４μｍ，比表面積が１２０m2/g
のγ−アルミナ粉体に塩化白金酸H2PtCl6 水溶液を加
え、乾燥後６００℃の温度で３ｈ熱処理してγ−アルミ
ナ粉体に３重量％の割合で白金を担持した。白金の担持
されたγ−アルミナ粉体をボールミルで粉砕したのち、
エチルシリケート，エチルセルロース，カルビトール等
を適量加え、混練して粘度が３００ないし４００ポイズ
の第二の酸化燃焼層用のペーストを得た。得られた第二
の酸化燃焼層用のペーストを所定のパターンによりスク
リーン印刷し、１２０℃で２ｈ乾燥した。Platinum electrode paste was screen-printed on the two main surfaces of the substrate 1 in a predetermined pattern and dried to about 1100.
It was fired at a temperature of ° C. A heater paste made of ruthenium oxide was screen-printed in a predetermined pattern and fired at a predetermined temperature. Central particle size 4μm, specific surface area 120m 2 / g
A chloroplatinic acid H 2 PtCl 6 aqueous solution was added to the γ-alumina powder of Example 1 and dried, and then heat-treated at a temperature of 600 ° C. for 3 hours to support 3% by weight of platinum on the γ-alumina powder. After pulverizing the platinum-supported γ-alumina powder with a ball mill,
Ethyl silicate, ethyl cellulose, carbitol, etc. were added in appropriate amounts and kneaded to obtain a paste for the second oxidative combustion layer having a viscosity of 300 to 400 poise. The obtained paste for the second oxidation combustion layer was screen-printed in a predetermined pattern and dried at 120 ° C. for 2 hours.
【００３７】酸化スズ粉体を乾燥空気中で温度７３０℃
で２ｈ処理し、得られた酸化スズ粉体に塩化パラジウム
水溶液を含浸し混練したのち乾燥した。この粉体を温度
６００℃で３ｈ熱処理し、塩化パラジウムを分解して酸
化スズ粉体上にパラジウムPdを２重量％の割合で担持し
た。得られた粉体をボールミルで粉砕したのち、エチル
シリケート、エチルセルロース、カルビトール等を適量
加え、混練して感ガス層用のペーストを得た。得られた
感ガス層用のペーストを所定のパターンによりスクリー
ン印刷し、１２０℃で２ｈ乾燥した。The tin oxide powder is dried in air at a temperature of 730 ° C.
The obtained tin oxide powder was impregnated with an aqueous solution of palladium chloride, kneaded, and then dried. This powder was heat-treated at a temperature of 600 ° C. for 3 hours to decompose the palladium chloride and carry 2% by weight of palladium Pd on the tin oxide powder. The obtained powder was pulverized with a ball mill, and then an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a gas-sensitive layer paste. The obtained gas-sensitive layer paste was screen-printed in a predetermined pattern and dried at 120 ° C. for 2 hours.
【００３８】中心粒径４μｍ，比表面積が１２０m2/gの
γ−アルミナ粉体に塩化白金酸H2PtCl6 水溶液を加え、
乾燥後６００℃の温度で３ｈ熱処理してγ−アルミナ粉
体に３重量％の割合で白金を担持した。白金の担持され
たγ−アルミナ粉体をボールミルで粉砕したのち、エチ
ルシリケート，エチルセルロース，カルビトール等を適
量加え、混練して粘度が３００ないし４００ポイズの第
三の酸化燃焼層用のペーストを得た。得られた第三の酸
化燃焼層用のペーストを所定のパターンによりスクリー
ン印刷し、１２０℃で２ｈ乾燥した。A chloroplatinic acid H 2 PtCl 6 aqueous solution was added to γ-alumina powder having a central particle size of 4 μm and a specific surface area of 120 m 2 / g,
After drying, the γ-alumina powder was heat-treated at 600 ° C. for 3 hours to support platinum at a ratio of 3% by weight. Platinum-supported γ-alumina powder was crushed with a ball mill, and then an appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added and kneaded to obtain a paste for the third oxidative combustion layer having a viscosity of 300 to 400 poise. It was The obtained paste for the third oxidative combustion layer was screen-printed with a predetermined pattern and dried at 120 ° C. for 2 hours.
【００３９】感ガス層と第二の酸化燃焼層と第三の酸化
燃焼層を印刷し乾燥した後にこれらを６３０℃の温度で
３ｈ同時に焼成して感ガス層４、第二の酸化燃焼層３
Ｂ、第三の酸化燃焼層３Ｃを形成した。焼成後の感ガス
層４と第二の酸化燃焼層３Ｂと第三の酸化燃焼層３Ｃの
厚さはそれぞれ２０μｍ、５０μｍ、５０μｍであっ
た。The gas-sensitive layer, the second oxidation-combustion layer and the third oxidation-combustion layer are printed and dried, and then these are simultaneously fired at a temperature of 630 ° C. for 3 hours so that the gas-sensing layer 4, the second oxidation-combustion layer 3
B, the third oxidation combustion layer 3C was formed. The thicknesses of the gas sensitive layer 4, the second oxidative combustion layer 3B and the third oxidative combustion layer 3C after firing were 20 μm, 50 μm and 50 μm, respectively.
【００４０】第二の酸化燃焼層、第三の酸化燃焼層はプ
ロパン，メタン等の厚膜ガスセンサの検知対象ガスに対
する干渉ガスであるアルコールガス等による誤報を防止
する。アルコールガス等は貴金属触媒により容易に酸化
されやすく第二の酸化燃焼層と第三の酸化燃焼層により
選択的に燃焼させることができる。さらに第二の酸化燃
焼層と第三の酸化燃焼層は共同して酸素の供給速度を高
めて、初期鳴動時間を短くすることができる。The second oxidative combustion layer and the third oxidative combustion layer prevent false alarms due to alcohol gas or the like which is an interference gas with respect to the gas to be detected by the thick film gas sensor such as propane and methane. Alcohol gas is easily oxidized by the noble metal catalyst and can be selectively burned by the second oxidation combustion layer and the third oxidation combustion layer. Furthermore, the second oxidizing combustion layer and the third oxidizing combustion layer can cooperate to increase the oxygen supply rate and shorten the initial ringing time.
【００４１】続いて電極２，２Ａにそれぞれ白金リード
線７，９を接続して厚膜ガスセンサを得た。それぞれの
リード線を警報器の回路に接続した。実施例２と比較例
２に示す厚膜ガスセンサの抵抗値につきその経時的安定
性を検討した。実施例１と比較例１に示す特性とほぼ同
一の特性が得られた。初期鳴動時間は第二の酸化燃焼層
と第三の酸化燃焼層を有するため従来の１／４であり、
３０ｓであった。 応用例 図５はこの発明の応用例に係る厚膜ガスセンサを示す平
面図である。Subsequently, platinum lead wires 7 and 9 were respectively connected to the electrodes 2 and 2A to obtain a thick film gas sensor. Each lead wire was connected to the alarm circuit. The stability over time of the resistance values of the thick film gas sensors shown in Example 2 and Comparative Example 2 was examined. The characteristics substantially the same as those shown in Example 1 and Comparative Example 1 were obtained. The initial ringing time is 1/4 of the conventional one because it has the second oxidation combustion layer and the third oxidation combustion layer,
It was 30 seconds. Application Example FIG. 5 is a plan view showing a thick film gas sensor according to an application example of the present invention.
【００４２】図６はこの発明の応用例に係る厚膜ガスセ
ンサを示す図５のＢ−Ｂ断面図である。この発明の応用
例に係る厚膜ガスセンサの構造は次の通りである。基板
１の一主面上に離間して二つの電極２が設けられる。基
板１と一対の電極２の上に感ガス層４が選択的に形成さ
れる。電極２にリード線７が接続される。基板１の他の
主面には電極２Ａが形成され、電極２Ａと基板１の上に
選択的にヒータ８が形成され、電極２Ａにはリード線９
が接続される。FIG. 6 is a sectional view taken along line BB of FIG. 5 showing a thick film gas sensor according to an application example of the present invention. The structure of the thick film gas sensor according to the application example of the present invention is as follows. Two electrodes 2 are provided on one main surface of the substrate 1 at a distance from each other. The gas sensitive layer 4 is selectively formed on the substrate 1 and the pair of electrodes 2. The lead wire 7 is connected to the electrode 2. An electrode 2A is formed on the other main surface of the substrate 1, a heater 8 is selectively formed on the electrode 2A and the substrate 1, and a lead wire 9 is formed on the electrode 2A.
Are connected.
【００４３】基板１は厚さ０．５ｍｍで縦３ｍｍ、横３
ｍｍの研磨されたアルミナ基板である。ヒータは酸化ル
テニウム抵抗体からなる。このような厚膜ガスセンサは
次のようにして調製される。基板１の二つの主面に白金
電極ペーストを所定のパターンでスクリーン印刷し、乾
燥後約１１００℃の温度で焼成した。酸化ルテニウムか
らなるヒータ用ペーストを所定のパターンでスクリーン
印刷し所定の温度で焼成した。The substrate 1 has a thickness of 0.5 mm and a length of 3 mm and a width of 3 mm.
mm polished alumina substrate. The heater comprises a ruthenium oxide resistor. Such a thick film gas sensor is prepared as follows. A platinum electrode paste was screen-printed on the two main surfaces of the substrate 1 in a predetermined pattern, dried, and then baked at a temperature of about 1100 ° C. A heater paste made of ruthenium oxide was screen-printed in a predetermined pattern and fired at a predetermined temperature.
【００４４】中心粒径４μｍ，比表面積が１２０m2/gの
γ−アルミナ粉体に塩化パラジウム水溶液を含浸し、乾
燥後６００℃の温度で３ｈ熱処理してγ−アルミナ粉体
にパラジウPdを５重量％の割合で担持した。中心粒径が
２μｍの酸化スズ粉体を乾燥空気中で温度７３０℃で２
ｈ処理し、得られた酸化スズ粉体に前記パラジウPd付き
γ−アルミナ粉体を酸化スズ粉体に対しアルミナとして
４重量％の割合で添加した。エタノールを分散媒として
湿式混合し、３００℃の温度で３ｈ乾燥してエタノール
を完全に除去した。A γ-alumina powder having a central particle size of 4 μm and a specific surface area of 120 m 2 / g was impregnated with an aqueous palladium chloride solution, dried, and then heat-treated at a temperature of 600 ° C. for 3 hours to add 5 parts of palladium Pd to the γ-alumina powder. The loading was carried out at a weight percentage. 2 tin oxide powder with a median particle size of 2 μm in dry air at a temperature of 730 ° C
The γ-alumina powder with palladium (Pd) was added to the tin oxide powder obtained by the h treatment at a ratio of 4% by weight as alumina to the tin oxide powder. Wet mixing was performed using ethanol as a dispersion medium, and the mixture was dried at a temperature of 300 ° C. for 3 hours to completely remove ethanol.
【００４５】得られた混合粉体にエチルシリケート，エ
チルセルロース，カルビトール等を適量加え混練して粘
度が３００ないし４００ポイズの感ガス層用ペーストを
得た。得られたペーストを所定のパターンにより所定の
厚さにスクリーン印刷し、１２０℃で２ｈ乾燥した。感
ガス層を印刷し乾燥した後に６３０℃の温度で３ｈ焼成
して感ガス層４を形成した。焼成後の感ガス層の厚さは
２０μｍであった。An appropriate amount of ethyl silicate, ethyl cellulose, carbitol, etc. was added to the obtained mixed powder and kneaded to obtain a gas-sensitive layer paste having a viscosity of 300 to 400 poise. The obtained paste was screen-printed with a predetermined pattern to a predetermined thickness and dried at 120 ° C. for 2 hours. The gas-sensitive layer was printed, dried and then baked at a temperature of 630 ° C. for 3 hours to form a gas-sensitive layer 4. The thickness of the gas sensitive layer after firing was 20 μm.
【００４６】続いて電極２，２Ａにそれぞれ白金リード
線７，９を接続して厚膜ガスセンサを得た。それぞれの
リード線を警報器の回路に接続した。応用例に係る厚膜
ガスセンサは酸化燃焼層を有しないが干渉ガスを前処理
して除去する場合や干渉ガスが初めから存在しない場合
等に有効に応用することができる。Subsequently, platinum lead wires 7 and 9 were respectively connected to the electrodes 2 and 2A to obtain a thick film gas sensor. Each lead wire was connected to the alarm circuit. The thick film gas sensor according to the application example does not have an oxidative combustion layer, but can be effectively applied to a case where interfering gas is pretreated and removed, or when the interfering gas does not exist from the beginning.
【００４７】図８は応用例に係る厚膜ガスセンサにつき
抵抗値の経時特性（ハ）を示す線図である。 実施例３ 図９は第三の発明の実施例に係る厚膜ガスセンサを示す
平面図である。図１０は第三の発明の実施例に係る厚膜
ガスセンサを示す断面図である。FIG. 8 is a diagram showing a time-dependent characteristic (c) of the resistance value of the thick film gas sensor according to the application example. Embodiment 3 FIG. 9 is a plan view showing a thick film gas sensor according to an embodiment of the third invention. FIG. 10 is a sectional view showing a thick film gas sensor according to an embodiment of the third invention.
【００４８】このガスセンサは白金を担持されない感ガ
ス層４Ａが第二と第三の酸化燃焼層３Ｂ、３Ｃにより挟
まれる。このようなガスセンサは以下のようにして調製
される。平均粒径２μｍの酸化スズ粉体に塩化白金酸を
白金として２ないし１０重量％となるように含浸し、６
００℃で３ｈ加熱して金属白金に分解した。この白金の
担持された酸化スズ粉体に水とシリカゾルを加え、酸化
燃焼層用のペーストを調製した。得られた酸化燃焼層用
のペーストを電極２の形成されたアルミナ製基板１の上
に２０μｍの厚さに塗布し６５０℃で３ｈ焼成して第二
の酸化燃焼層３Ｂを積層した。続いて平均粒径２μｍの
酸化スズ粉体に水とシリカゾルを加え、感ガス層用のペ
ーストを調製した。得られた感ガス層用のペーストを前
記第二の酸化燃焼層３Ｂと電極２の上に４０μｍの厚さ
に塗布し６５０℃で３ｈ焼成して感ガス層４Ａを形成し
た。次いで前記酸化燃焼層用のペーストを電極２と感ガ
ス層４Ａの上に４０μｍの厚さに塗布し６５０℃で３ｈ
焼成して第三の酸化燃焼層３Ｃを積層した。なお触媒と
して白金に替えてパラジウムを用いることもできる。ま
た感ガス層は酸化スズに替えて酸化亜鉛を用いることも
できる。 比較例３ 第二の酸化燃焼層を形成しない他は実施例３と同様にし
て厚膜ガスセンサを形成した。In this gas sensor, a gas sensitive layer 4A which does not carry platinum is sandwiched by second and third oxidative combustion layers 3B and 3C. Such a gas sensor is prepared as follows. A tin oxide powder having an average particle diameter of 2 μm was impregnated with chloroplatinic acid as platinum to a concentration of 2 to 10% by weight.
It was decomposed into metallic platinum by heating at 00 ° C. for 3 hours. Water and silica sol were added to the platinum-supported tin oxide powder to prepare a paste for the oxidation combustion layer. The obtained paste for oxidative combustion layer was applied on the alumina substrate 1 on which the electrode 2 was formed to a thickness of 20 μm and baked at 650 ° C. for 3 hours to laminate the second oxidative combustion layer 3B. Subsequently, water and silica sol were added to tin oxide powder having an average particle size of 2 μm to prepare a paste for a gas sensitive layer. The obtained gas-sensitive layer paste was applied on the second oxidative combustion layer 3B and the electrode 2 to a thickness of 40 μm and baked at 650 ° C. for 3 hours to form a gas-sensitive layer 4A. Then, the paste for the oxidizing combustion layer is applied on the electrode 2 and the gas-sensitive layer 4A to a thickness of 40 μm, and the paste is applied at 650 ° C. for 3 hours.
The third oxidative combustion layer 3C was laminated by firing. Palladium may be used as the catalyst instead of platinum. Further, zinc oxide can be used instead of tin oxide for the gas sensitive layer. Comparative Example 3 A thick film gas sensor was formed in the same manner as in Example 3 except that the second oxidizing combustion layer was not formed.
【００４９】図１１は第三の発明の実施例に係る厚膜ガ
スセンサにつき初期応答時間の放置時間依存性（ホ）を
比較例３に係る厚膜ガスセンサの特性（ニ）と対比して
示す線図である。放置時間により初期応答時間は飽和す
るが、第三の発明の実施例に係る厚膜ガスセンサの初期
応答特性は比較例に係る厚膜ガスセンサの特性と比較し
て１／４の初期応答時間になっていることがわかる。酸
化亜鉛を用いた厚膜ガスセンサにおいても同様な特性が
得られる。FIG. 11 is a line showing the dependence of the initial response time on the leaving time (e) for the thick film gas sensor according to the third embodiment of the invention in comparison with the characteristic (d) of the thick film gas sensor according to Comparative Example 3. It is a figure. Although the initial response time is saturated depending on the standing time, the initial response characteristic of the thick film gas sensor according to the example of the third invention is 1/4 of the initial response time as compared with the characteristic of the thick film gas sensor according to the comparative example. You can see that Similar characteristics can be obtained in a thick film gas sensor using zinc oxide.
【００５０】[0050]
【発明の効果】第一の発明によれば金属酸化物半導体の
抵抗値の変化を利用してガスの有無を検出する厚膜ガス
センサであって、基板と、一対の電極と、第一の酸化燃
焼層と、感ガス層とを包含し、基板はガスセンサの支持
体であり、一対の電極は基板上に離間して直接的に被着
され、感ガス層は基板と一対の電極上に選択的に積層さ
れ、第一の酸化燃焼層は感ガス層の全部を被覆して積層
され、感ガス層は第一の貴金属触媒を担持した比表面積
の大きな第一の金属酸化物を金属酸化物半導体に含有し
てなり、第一の酸化燃焼層は第二の貴金属触媒を第二の
金属酸化物に担持してなるとし、また第二の発明によれ
ば金属酸化物半導体の抵抗値の変化を利用してガスの有
無を検出する厚膜ガスセンサであって、基板と、一対の
電極と、第二の酸化燃焼層と、感ガス層と、第三の酸化
燃焼層とを包含し、基板はガスセンサの支持体であり、
一対の電極は基板上に離間して直接的に被着され、第二
の酸化燃焼層は基板と一対の電極上に選択的に積層さ
れ、感ガス層は第二の酸化燃焼層と一対の電極上に選択
的に積層され、第三の酸化燃焼層は感ガス層の全部を被
覆して積層され、感ガス層は第一の貴金属触媒を担持し
た比表面積の大きな第一の金属酸化物を金属酸化物半導
体に含有してなり、第二の酸化燃焼層は第二の貴金属触
媒を第二の金属酸化物に担持してなり、第三の酸化燃焼
層は第二の貴金属触媒を第二の金属酸化物に担持してな
るとするので、比表面積の大きな第一の金属酸化物は貴
金属触媒を担持したときに貴金属触媒が粒成長をおこす
ことがなく触媒活性が長期に維持され、その結果センサ
抵抗値が経時的に安定であるとともに初期鳴動特性にも
優れる厚膜ガスセンサが得られる。According to the first aspect of the present invention, there is provided a thick film gas sensor for detecting the presence / absence of gas by utilizing the change in the resistance value of a metal oxide semiconductor, which comprises a substrate, a pair of electrodes, and a first oxide. Including a combustion layer and a gas sensitive layer, the substrate is a support for the gas sensor, the pair of electrodes is directly and separately deposited on the substrate, and the gas sensitive layer is selected on the substrate and the pair of electrodes. The first oxidation combustion layer is laminated so as to cover the entire gas-sensitive layer, and the gas-sensitive layer is a metal oxide containing a first metal oxide carrying a first noble metal catalyst and having a large specific surface area. It is contained in a semiconductor, and the first oxidation combustion layer has a second noble metal catalyst supported on a second metal oxide, and according to the second invention, a change in the resistance value of the metal oxide semiconductor. A thick film gas sensor for detecting the presence or absence of gas by utilizing a substrate, a pair of electrodes, and a second acid. A combustion layer, includes a gas sensing layer, and a third oxide combustion layer, the substrate is a substrate of the gas sensor,
The pair of electrodes are directly deposited on the substrate while being separated from each other, the second oxidative combustion layer is selectively laminated on the substrate and the pair of electrodes, and the gas-sensitive layer is a pair of the second oxidative combustion layer and the pair of electrodes. Selectively laminated on the electrode, the third oxidative combustion layer covers the entire gas-sensitive layer, and the gas-sensitive layer is the first metal oxide having a large specific surface area and carrying the first noble metal catalyst. In a metal oxide semiconductor, the second oxidation combustion layer has a second noble metal catalyst supported on the second metal oxide, and the third oxidation combustion layer has a second noble metal catalyst. Since the first metal oxide having a large specific surface area is supported on the second metal oxide, the noble metal catalyst does not cause grain growth when the noble metal catalyst is supported, and the catalytic activity is maintained for a long time. Result Thick film gas sensor with stable sensor resistance over time and excellent initial ringing characteristics It is obtained.
【００５１】また第三の発明によれば金属酸化物半導体
の抵抗値の変化を利用してガスの有無を検出する厚膜ガ
スセンサであって、（１）基板と、（２）一対の電極
と、（３）第二の酸化燃焼層と、（４）感ガス層と、
（３）第三の酸化燃焼層とを包含し、基板はガスセンサ
の支持体であり、一対の電極は基板上に離間して直接的
に被着され、第二の酸化燃焼層は基板と一対の電極上に
選択的に積層され、感ガス層は第二の酸化燃焼層と一対
の電極上に選択的に積層され、第三の酸化燃焼層は感ガ
ス層の全部を被覆して積層され、感ガス層は金属酸化物
半導体からなり、第二の酸化燃焼層は貴金属触媒を第三
の金属酸化物に担持してなり、第三の酸化燃焼層は貴金
属触媒を第三の金属酸化物に担持してなるとするので、
第二と第三の酸化燃焼層により感ガス層に酸素が供給さ
れることとなり初期鳴動時間が短縮されるとともに感ガ
ス層は触媒を担持しないために感ガス層の抵抗値の安定
性した厚膜ガスセンサが得られる。According to a third aspect of the present invention, there is provided a thick film gas sensor for detecting the presence or absence of gas by utilizing the change in the resistance value of a metal oxide semiconductor, comprising (1) a substrate and (2) a pair of electrodes. , (3) second oxidative combustion layer, (4) gas sensitive layer,
(3) Including a third oxidative combustion layer, the substrate is a support of the gas sensor, the pair of electrodes are directly spaced apart and directly applied on the substrate, and the second oxidative combustion layer is paired with the substrate. , The gas-sensitive layer is selectively laminated on the second oxidation combustion layer and the pair of electrodes, and the third oxidation-combustion layer is laminated to cover the entire gas-sensing layer. , The gas-sensitive layer is made of a metal oxide semiconductor, the second oxidation combustion layer has a noble metal catalyst supported on a third metal oxide, and the third oxidation combustion layer has a noble metal catalyst made of a third metal oxide. Since it will be carried on
Oxygen is supplied to the gas-sensitive layer by the second and third oxidative combustion layers, and the initial ringing time is shortened, and since the gas-sensitive layer does not carry a catalyst, the gas-sensitive layer has a stable resistance value. A membrane gas sensor is obtained.
【図１】第一の発明の実施例に係る厚膜ガスセンサを示
す平面図FIG. 1 is a plan view showing a thick film gas sensor according to an embodiment of the first invention.
【図２】第一の発明の実施例に係る厚膜ガスセンサを示
す図１のＡ−Ａ矢視断面図FIG. 2 is a sectional view taken along the line AA of FIG. 1 showing a thick film gas sensor according to an embodiment of the first invention.
【図３】第二の発明の実施例に係る厚膜ガスセンサを示
す平面図FIG. 3 is a plan view showing a thick film gas sensor according to an embodiment of the second invention.
【図４】第二の発明の実施例に係る厚膜ガスセンサを示
す図３のＤ−Ｄ矢視断面図FIG. 4 is a sectional view taken along the line DD of FIG. 3, showing a thick film gas sensor according to an embodiment of the second invention.
【図５】この発明の応用例に係る厚膜ガスセンサを示す
平面図FIG. 5 is a plan view showing a thick film gas sensor according to an application example of the invention.
【図６】この発明の応用例に係る厚膜ガスセンサを示す
図５のＢ−Ｂ矢視断面図6 is a sectional view taken along the line BB in FIG. 5 showing a thick film gas sensor according to an application example of the invention.
【図７】第一の発明の実施例に係る厚膜ガスセンサの抵
抗値につきその経時特性（イ）を比較例に係る厚膜ガス
センサの特性（ロ）と対比して示す線図FIG. 7 is a diagram showing the resistance characteristics of the thick film gas sensor according to the embodiment of the first invention (a) as a function of time and the characteristics (b) of the thick film gas sensor according to the comparative example.
【図８】この発明の応用例に係る厚膜ガスセンサにつき
抵抗値の経時特性（ハ）を示す線図FIG. 8 is a diagram showing a time-dependent characteristic (C) of a resistance value of a thick film gas sensor according to an application example of the invention.
【図９】第三の発明の実施例に係る厚膜ガスセンサを示
す平面図FIG. 9 is a plan view showing a thick film gas sensor according to an embodiment of the third invention.
【図１０】第三の発明の実施例に係る厚膜ガスセンサを
示す断面図FIG. 10 is a sectional view showing a thick film gas sensor according to an embodiment of the third invention.
【図１１】第三の発明の実施例に係る厚膜ガスセンサに
つき初期応答時間の放置時間依存性（ホ）を比較例３に
係る厚膜ガスセンサの特性（ニ）と対比して示す線図FIG. 11 is a diagram showing the dependence of the initial response time on standing time (e) for the thick film gas sensor according to the example of the third invention in comparison with the characteristic (d) of the thick film gas sensor according to comparative example 3.
【図１２】従来の厚膜ガスセンサの初期鳴動特性を示す
線図FIG. 12 is a diagram showing an initial ringing characteristic of a conventional thick film gas sensor.
【図１３】従来の厚膜ガスセンサを示す平面図FIG. 13 is a plan view showing a conventional thick film gas sensor.
【図１４】従来の厚膜ガスセンサを示す図１３のＣ−Ｃ
矢視断面図FIG. 14 is a CC of FIG. 13 showing a conventional thick film gas sensor.
Sectional view
１ 基板 ２ 電極 ２Ａ 電極 ３ 酸化燃焼層 ３Ａ 酸化燃焼層 ３Ｂ 酸化燃焼層 ３Ｃ 酸化燃焼層 ４ 感ガス層 ４Ａ 感ガス層 ７ リード線 ８ ヒータ ９ リード線 １０ 第一の金属酸化物 １１ 金属酸化物半導体 1 Substrate 2 Electrode 2A Electrode 3 Oxidation Combustion Layer 3A Oxidation Combustion Layer 3B Oxidation Combustion Layer 3C Oxidation Combustion Layer 4 Gas Sensitive Layer 4A Gas Sensitive Layer 7 Lead Wire 8 Heater 9 Lead Wire 10 First Metal Oxide 11 Metal Oxide Semiconductor
Claims (15)
てガスの有無を検出する厚膜ガスセンサであって、 （１）基板と、 （２）一対の電極と、 （３）第一の酸化燃焼層と、 （４）感ガス層とを包含し、 基板はガスセンサの支持体であり、 一対の電極は基板上に離間して直接的に被着され、 感ガス層は基板と一対の電極上に選択的に積層され、 第一の酸化燃焼層は感ガス層の全部を被覆して積層さ
れ、 感ガス層は第一の貴金属触媒を担持した比表面積の大き
な第一の金属酸化物を金属酸化物半導体に含有してな
り、 第一の酸化燃焼層は第二の貴金属触媒を第二の金属酸化
物に担持してなることを特徴とする厚膜ガスセンサ。1. A thick film gas sensor for detecting the presence or absence of gas by utilizing a change in resistance of a metal oxide semiconductor, comprising: (1) a substrate, (2) a pair of electrodes, and (3) a first electrode. And the (4) gas sensitive layer, the substrate is a support of the gas sensor, the pair of electrodes are directly and separately deposited on the substrate, and the gas sensitive layer is paired with the substrate. Is selectively laminated on the electrode, the first oxidation combustion layer covers the entire gas-sensitive layer, and the gas-sensitive layer is the first metal oxide having a large specific surface area and carrying the first noble metal catalyst. A thick film gas sensor comprising a metal oxide semiconductor containing a substance, and the first oxidation combustion layer having a second noble metal catalyst supported on a second metal oxide.
てガスの有無を検出する厚膜ガスセンサであって、 （１）基板と、 （２）一対の電極と、 （３）第二の酸化燃焼層と、 （４）感ガス層と、 （３）第三の酸化燃焼層とを包含し、 基板はガスセンサの支持体であり、 一対の電極は基板上に離間して直接的に被着され、 第二の酸化燃焼層は基板と一対の電極上に選択的に積層
され、 感ガス層は第二の酸化燃焼層と一対の電極上に選択的に
積層され、 第三の酸化燃焼層は感ガス層の全部を被覆して積層さ
れ、 感ガス層は第一の貴金属触媒を担持した比表面積の大き
な第一の金属酸化物を金属酸化物半導体に含有してな
り、 第二の酸化燃焼層は第二の貴金属触媒を第二の金属酸化
物に担持してなり、 第三の酸化燃焼層は第二の貴金属触媒を第二の金属酸化
物に担持してなることを特徴とする厚膜ガスセンサ。2. A thick film gas sensor for detecting the presence or absence of gas by utilizing a change in the resistance value of a metal oxide semiconductor, comprising: (1) a substrate, (2) a pair of electrodes, and (3) a second electrode. Including the oxidation combustion layer of (4), the gas-sensitive layer (3), and the third oxidation combustion layer (3), the substrate is a support of the gas sensor, and the pair of electrodes are directly separated from each other on the substrate. The second oxidation combustion layer is selectively laminated on the substrate and the pair of electrodes, and the gas-sensitive layer is selectively laminated on the second oxidation combustion layer and the pair of electrodes. The combustion layer is laminated so as to cover the entire gas-sensitive layer, and the gas-sensitive layer contains the first metal oxide having a large specific surface area and carrying the first noble metal catalyst in the metal oxide semiconductor. The oxidative combustion layer of is a second noble metal catalyst supported on a second metal oxide, and the third oxidative combustion layer is a second noble metal catalyst. A thick film gas sensor comprising: a metal oxide supported on a second metal oxide.
において、金属酸化物半導体はｎ型金属酸化物半導体で
あることを特徴とする厚膜ガスセンサ。3. The thick film gas sensor according to claim 1 or 2, wherein the metal oxide semiconductor is an n-type metal oxide semiconductor.
て、ｎ型金属酸化物半導体は酸化スズであることを特徴
とする厚膜ガスセンサ。4. The thick film gas sensor according to claim 3, wherein the n-type metal oxide semiconductor is tin oxide.
て、ｎ型金属酸化物半導体は酸化亜鉛であることを特徴
とする厚膜ガスセンサ。5. The thick film gas sensor according to claim 3, wherein the n-type metal oxide semiconductor is zinc oxide.
において、比表面積の大きな第一の金属酸化物は活性ア
ルミナ，活性シリカ，活性シリカアルミナの群から選ば
れた少なくとも一つからなることを特徴とする厚膜ガス
センサ。6. The thick film gas sensor according to claim 1 or 2, wherein the first metal oxide having a large specific surface area is at least one selected from the group consisting of activated alumina, activated silica and activated silica alumina. A thick film gas sensor.
において、第一の貴金属触媒は白金またはパラジウムの
群から選ばれた少なくとも一つであることを特徴とする
厚膜ガスセンサ。7. The thick film gas sensor according to claim 1 or 2, wherein the first noble metal catalyst is at least one selected from the group consisting of platinum and palladium.
において、第一の貴金属触媒は第一の金属酸化物に３な
いし１５重量％の割合で担持されることを特徴とする厚
膜ガスセンサ。8. The thick film gas sensor according to claim 1 or 2, wherein the first noble metal catalyst is supported on the first metal oxide in a proportion of 3 to 15% by weight. .
において、第一の貴金属触媒を担持した第一の金属酸化
物は金属酸化物半導体に３ないし１０重量％の割合で含
有されることを特徴とする厚膜ガスセンサ。9. The thick film gas sensor according to claim 1 or 2, wherein the first metal oxide carrying the first noble metal catalyst is contained in the metal oxide semiconductor in a ratio of 3 to 10% by weight. A thick film gas sensor.
サにおいて、第二の貴金属触媒は白金またはパラジウム
の群から選ばれた少なくとも一つであることを特徴とす
る厚膜ガスセンサ。10. The thick film gas sensor according to claim 1 or 2, wherein the second noble metal catalyst is at least one selected from the group consisting of platinum and palladium.
サにおいて、第二の金属酸化物はγ−アルミナであるこ
とを特徴とする厚膜ガスセンサ。11. The thick film gas sensor according to claim 1 or 2, wherein the second metal oxide is γ-alumina.
してガスの有無を検出する厚膜ガスセンサであって、 （１）基板と、 （２）一対の電極と、 （３）第二の酸化燃焼層と、 （４）感ガス層と、 （３）第三の酸化燃焼層とを包含し、 基板はガスセンサの支持体であり、 一対の電極は基板上に離間して直接的に被着され、 第二の酸化燃焼層は基板と一対の電極上に選択的に積層
され、 感ガス層は第二の酸化燃焼層と一対の電極上に選択的に
積層され、 第三の酸化燃焼層は感ガス層の全部を被覆して積層さ
れ、 感ガス層は金属酸化物半導体からなり、 第二の酸化燃焼層は貴金属触媒を第三の金属酸化物に担
持してなり、 第三の酸化燃焼層は貴金属触媒を第三の金属酸化物に担
持してなることを特徴とする厚膜ガスセンサ。12. A thick film gas sensor for detecting the presence or absence of gas by utilizing a change in resistance value of a metal oxide semiconductor, comprising: (1) a substrate, (2) a pair of electrodes, and (3) a second electrode. Including the oxidation combustion layer of (4), the gas-sensitive layer (3), and the third oxidation combustion layer (3), the substrate is a support of the gas sensor, and the pair of electrodes are directly separated from each other on the substrate. The second oxidation combustion layer is selectively laminated on the substrate and the pair of electrodes, and the gas-sensitive layer is selectively laminated on the second oxidation combustion layer and the pair of electrodes. The combustion layer is laminated so as to cover the entire gas-sensitive layer, the gas-sensitive layer is made of a metal oxide semiconductor, and the second oxidation combustion layer is made by supporting a noble metal catalyst on a third metal oxide. The thick film gas sensor is characterized in that the oxidative combustion layer of No. 1 comprises a noble metal catalyst supported on a third metal oxide.
いて、貴金属触媒は白金またはパラジウムの群から選ば
れた少なくとも一つであることを特徴とする厚膜ガスセ
ンサ。13. The thick film gas sensor according to claim 12, wherein the noble metal catalyst is at least one selected from the group consisting of platinum and palladium.
いて、第三の金属酸化物は金属酸化物半導体であること
を特徴とする厚膜ガスセンサ。14. The thick film gas sensor according to claim 12, wherein the third metal oxide is a metal oxide semiconductor.
いて、貴金属触媒は第三の金属酸化物に２ないし１０重
量％の割合で担持されることを特徴とする厚膜ガスセン
サ。15. The thick film gas sensor according to claim 12, wherein the noble metal catalyst is supported on the third metal oxide at a ratio of 2 to 10% by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20350793A JPH0743331A (en) | 1993-05-28 | 1993-08-18 | Thick film gas sensor |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12639993 | 1993-05-28 | ||
| JP5-126399 | 1993-05-28 | ||
| JP20350793A JPH0743331A (en) | 1993-05-28 | 1993-08-18 | Thick film gas sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0743331A true JPH0743331A (en) | 1995-02-14 |
Family
ID=26462593
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20350793A Pending JPH0743331A (en) | 1993-05-28 | 1993-08-18 | Thick film gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0743331A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006258423A (en) * | 2005-03-15 | 2006-09-28 | Fuji Electric Fa Components & Systems Co Ltd | Printing paste for gas selective combustion layer |
| KR20210099403A (en) * | 2020-02-04 | 2021-08-12 | (주)한국아이티에스 | Apparatus of transfering semiconductor single crystal ingot |
-
1993
- 1993-08-18 JP JP20350793A patent/JPH0743331A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006258423A (en) * | 2005-03-15 | 2006-09-28 | Fuji Electric Fa Components & Systems Co Ltd | Printing paste for gas selective combustion layer |
| KR20210099403A (en) * | 2020-02-04 | 2021-08-12 | (주)한국아이티에스 | Apparatus of transfering semiconductor single crystal ingot |
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