PURPOSE: To achieve a broader humidity detection range and a greater mechanical strength with a high sensitivity by a method wherein a kneaded matter of an initial polymer varnish of an organic silicon compound and an inorganic material is applied on an insulation substrate, hardened by heating under a crosslinking at a specified temperature following the volatization of a solvent and then, sintered below a specified temperature.
CONSTITUTION: A kneaded matter of a varnish having an initial polymer of a silicon resin such as methyl phenyl silicon dissolved in a solvent such as xylene and a metal oxide such as TiO2, SiO2 and MgO or metal such as Ge, V, Zr and Mo or a compound, such as carbonate, alkoxide thereof, which forms a metal oxide by heat is applied on an insulation substrate 1 made of Al2O3 or the like and the solvent is volatilized in a drying furnace after it is left alone in the air. Then, the product is hardened under a crosslinking at 160W250°C with an electric furnace and then, sintered below 1,000°C (preferably, 600W800°C). Thus, a porous humidity sensitive section 3 is obtained which has a broad effective humidity sensitive surface area and a large range of humidity detection with a high sensitivity free from cracking or the like during the sintering. An electrode 2 is formed with a Pt-Pd alloy paste and a lead 4 with a Pt wire on the humidity sensitive section 3 to obtain an excellent humidity sensor and a dew condensation sensor.
HORII HIROKO
MIYAO KUNIHIKO
