To prevent the oxidation of vanadium oxide ceramic so that the current limiter element may not malfunction by coating the surface of the nonelectrode part of the reistor consisting of vanadium oxide ceramic with an insulating oxidation preventive film.
As PTC ceramic resistor, V2O5 and CR2O3 are mixed, and pure water is added as a solvent, and they are crushed and mixed to get ceramic material, and its material is baked in hydrogen air current after drying so as to reduce V2O5 into V2O3. Furthermore, Fe2O3 and a binder are added to its V2O3, and again pure water is added as a solvent and then, they are smashed and mixed, and after drying, they are baked in hydrogen air current to get a columnar body 1 made of sintered vanadium oxide ceramics. On both sides of this columnar body 1, Ag-Cu eutectic solder foils are put, and they are caught with Mo electrodes 3, thus the electrodes are attached. Then, a zinc glass film 4 being an insulating oxidation preventive film is made around the columnar body 1. Accordingly, malfunction can be prevented by preventing the oxidation of the vanadium ceramics.
SUZUKI TAKUYA
KUNIHARA KENJI
SAKAI TAKAO
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