Ceramic heater

Abstract

Aluminum nitride, silicon nitride or silicon carbide is employed as the main component forming a substrate for increasing mechanical strength and improving thermal shock resistance, a proper additive is blended for controlling thermal conductivity and a temperature gradient from a heating element to an electrode is loosened for providing a dimensional ratio of the substrate effective for preventing oxidation of a contact between an electrode of the heating element and a connector of a feeding part. In a ceramic heater having an electrode and a heating element formed on the surface of a ceramic substrate, A/B≧20 is satisfied assuming that A represents the distance from a contact between a circuit of the heating element and the electrode to an end of the ceramic substrate closer to the electrode and B represents the thickness of the ceramic substrate, and the thermal conductivity of the ceramic substrate is adjusted to 30 to 80 W/m·K.

Dependencies are inferred from the claim text.