Conflux Ab

Gunnar Nyberg

Tom Francke

Joachim Sjöstrand

Per-Göran Mikael Mortenson

Lars-Ove Nilsson

Fredrik Von Wachenfeldt

Sjoestrand Joachim

Per-Goran Mikael Mortenson

A novel compound having exponential temperature dependent electrical resistivity comprises an electrically insulating bulk material (), electrically conductive particles () of a first kind, and electrically conductive particles () 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 () and the particles of the first kind comprise even surface portions (). The particles of the first and second kinds are arranged to form a plurality of current paths () through the compound, wherein each of the current paths comprises galvanically connected particles of the first and second kinds and a gap () between a tip () of one of the particles of the second kind and an even surface portion () of one of the particles of the first kind, which gap is narrow enough to allow electrons to tunnel through the gap via the quantum tunneling effect. The bulk material has a thermal expansion capability such that it expands with temperature, thereby increasing the gap widths (w) of the current paths, which in turn increases the electrical resistivity of the compound exponentially.

Compound having exponential temperature dependent electrical resistivity, use of such compound in a self-regulating heating element, self-regulating heating element comprising such compound, and method of forming such compound

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.

Heating element

Growing community of inventors

Täby, Sweden

Gunnar Nyberg