Abstract: A novel compound having exponential temperature dependent electrical resistivity comprises an electrically insulating bulk material (11), electrically conductive particles (12) of a first kind, and electrically conductive particles (13) of a second kind covered by a lubricant. The bulk material holds the particles of the first and second kinds in place therein; the particles of the second kind are smaller than the particles of the first kind; the particles of the second kind are more in number than the particles of the first kind; and the particles of the second kind have higher surface roughness than the particles of the first kind, wherein the particles of the second kind comprise tips (13a) and the particles of the first kind comprise even surface portions (12a).

Abstract: A method of manufacturing semi-manufactured PTC heating elements (10) comprises the steps of providing an electrically insulating support foil (11), providing an electrically conductive foil (12) from which at least two electrically conductive patterns separated from one another are to be formed, and laminating a PTC compound (13) between the electrically insulating support foil and the electrically conductive foil, wherein the PTC compound has adhesive properties for bonding the laminate together. Preferably, the electrically insulating support foil, the electrically conductive foil, and the semi-manufactured PTC heating elements are provided on rolls. PTC heating elements are manufactured by means of cutting the semi-manufactured PTC heating elements into suitable pieces, patterning and etching the electrically conductive patterns, and attaching electrically conductive terminals to the electrically conductive patterns.

Abstract: A positive temperature coefficient (PTC) superimposed impedance polymeric (SIP) compound including an electrically insulating matrix essentially consisting of a siloxane polymer in addition to first and second electrically conductive particles having different properties with respect to surface energies and electrical conductivities. A multi-layered, ZPZ, foil including a PTC SIP compound of the invention present between two metal foils, thereby forming a conductive composite body. A multi-layered device, including an essentially flat composite body made up from a PTC SIP compound according to the invention, two electrode layers adhering to the surfaces of the composite body, the electrode layers being metal foils prepared to connect to electrodes.

Abstract: A PTC SIP compound comprising an electrically insulating matrix essentially consisting of a siloxane polymer in addition to first and second electrically conductive particles having different properties with respect to surface energies and electrical conductivities. A multi-layered, ZPZ, foil comprising a PTC SIP compound of the invention present between two metal foils, thereby forming a conductive composite body. A multi-layered device, comprising an essentially flat composite body made up from a PTC SIP compound according to the invention, two electrode layers adhering to the surfaces of the composite body, the electrode layers being metal foils prepared to connect to electrodes.