FLAT PTC HEATER AND RESISTANCE VALUE REGULATING METHOD FOR THE SAME

摘要

A flat PTC heater according to the present invention is formed by bonding one or a plurality of thin plate type PTC ceramic members (1) on a surface of each of which a pair of electrodes are provided to an insulator (3). When more than one thin plate type PTC ceramic members (1) are provided, electrodes (2) of the same polarity are electrically parallel-connected by lead wires (6). The occurrence of warpage, leakage and short-circuiting is prevented by forming a layer (4) of an elastic insulating material on an electrode-carrying surface. The occurence of warpage after printing and firing operations is prevented by setting the thickness of the thin plate type PTC ceramic member to not less than 0.5 mm. In the resistance value regulating method according to the present invention, in which the resistance between the electrodes (2) on each PTC ceramic member (1) on the flat PTC heater is regulated, a conductive passage on an electrode pattern is cut off at an intermediate portion thereof, or predetermined portions (8) at which a conductive passage has been cut off in advance are connected by soldering, whereby the resistance between the PTC ceramic members is regulated. In a thin PTC plate unit according to the present invention, a PTC thermistor element having a pair of electrodes on one surface thereof is fixed directly and closely on an insulating board, and an insulating board is pasted on the other surface of the thermistor element.