Abstract: The invention provides a method of soldering a conductor on to a ceramic resistor body having a positive temperature coefficient, said method employing a soldering flux which is free of organic compounds having a high molecular weight. Preferably, the soldering flux comprises an aqueous solution of zinc chloride and hydrazine hydrochloride. The inventive method reduces the risk of explosion of soldered PTCs.

Abstract: A component consisting of two coupled PTC thermistors with the first thermistor having a lower cold resistance than the second thermistor and the first thermistor having a higher resistance at the operating temperature than the second thermistor. According to the invention, the electric connection to the second thermistor is made directly by solely mechanical contacts to the surface of the ceramic thermistor body. This means a considerable simplification during manufacture, as the second thermistor need not be provided with electrode layers.

Abstract: Self-regulating heating element comprising one or more PTC-resistor bodies enclosed in a synthetic resin filler material mixture. The potting compound is provided with channels. This prevents explosion.

Abstract: A controllable electric heating device uses a PTC resistance body having first areal electrode on one surface and two spaced apart areal electrodes of different areal size on the opposite surface in overlapping relation with a part of the first electrode to provide at least two current paths through the resistance body between the opposite surfaces. The first electrode is connected to one terminal of a voltage source. A switching device selectively connects one or more of the two spaced apart electrodes to the other terminal of the voltage source so that the effective electrode areas are altered thereby adjusting the current flow in the PTC body to produce different temperature levels of the heating device.