Abstract: An electronic device includes a first conductive polymer layer sandwiched between a first external metal foil electrode and a first internal metal foil electrode, a second conductive polymer layer sandwiched between a second internal metal foil electrode and a second external metal foil electrode, a layer of fiber-reinforced epoxy resin bonding the first and second internal electrodes together, a first terminal providing electrical contact between the first internal electrode and the second external electrode, and a second terminal providing electrical contact between the second internal electrode and the first external electrode. In a preferred embodiment, the polymer layers exhibit PTC behavior, and the terminals are formed by a solder layer applied over a plated layer of conductive metal. Insulative layers are preferably provided on the external electrodes, and located so as to insulate the first and second terminals from each other.

Abstract: A switching element, specifically an encoder element, is fabricated by forming a conductive track on an insulative substrate, and then screen printing an insulative layer on the track in a predetermined pattern that forms a contact array that comprises a plurality of conductive contacts separated by nonconductive areas. The substrate may be a polymeric resin, and the track comprises (a) a copper base layer formed on a surface of the substrate in the configuration of the track, (b) a first metal-plated layer, preferably of nickel, on the base layer, and (c) a second metal-plated layer, preferably of gold, on the first metal-plated layer. The insulative layer is formed of a thick film dielectric material comprising a difunctional monomer (e.g., diallyl isophthalate), a glycol ether ester (e.g., ethylene glycol monobutyl ether acetate), an inorganic filler (e.g., BaSO4), and an acetate surface modifier (e.g., an ethyl acrylate/ethylhexylacrylate copolymer).