| 摘要 |
PURPOSE:To prevent corrosion and erosion of an electrode and its junction and to reduce probability of disconnection of lead wires, by forming a sensitive film of metal oxide, lead wires, and electrodes connected with said film on one side of an insulating base, and covering the electrodes and the wires and their junctions perfectly with said films. CONSTITUTION:A gas sensitive film 6 is formed on one side of an insulating base 10 with a metal oxide, such as SnO2, to cover all of the electrodes 7 and their junctions 8a with the wires 8. A sheet heater 9 consisting mainly of RuO2 is fixed to the other side of the base 10. Since the electrodes 7 and the wires 8 are not exposed to the gas to be examined, corrosion and erosion are prevented and their lives are extended, so, the electrodes are formed by baking a conductive paste of nickel powder or the like without using a noble metal, such as Pt. Besides, lead wires 11 are passed through holes 12 penetrated in the thickness direction of the base 10, and only the films 6 of a sensor 14 are exposed to the gas flowing through a pipe 15 without exposing the wires 11, thus obtaining a long-lived sensor. |
