Surface-mountable conductive polymer devices include a conductive polymer layer between first and second electrodes, on which are disposed first and second insulation layers, respectively. First and second planar conductive terminals are on the second insulation layer. A first cross-conductor connects the second electrode to the first terminal, and is separated from the first electrode by a portion of the first insulation layer. A second cross-conductor connects the first electrode to the second terminal, and is separated from the second electrode by a portion of the second insulation layer. In some embodiments, at least one cross-conductor includes a beveled portion through the first insulation layer to provide enhanced adhesion between the cross-conductor and the first insulation layer, while allowing greater thermal expansion without undue stress. In other embodiments, these advantages are achieved by having at least one cross-conductor in physical contact with a metallized anchor pad on the first insulation layer.

A double-switching heater includes a double-switching PTC ink deposited on a substrate to form one or more resistors. The double-switching PTC ink has a first resin that provides a first PTC effect at a first temperature range and a second resin that provides a second PTC effect at a second temperature range, where the second temperature range is higher than the first temperature range. The substrate may be a flexible substrate or a rigid substrate, and may bedeformable to generate a three-dimensional structure. The substrate may be: polyester, polyimide, polyamide, polypropylene, thermoplastic polyurethane, fiberglass, cement board, carbon composite materials, polyethylene terephthalate, polyethylene, aluminum, steel, glass composite, molded plastic, high-density polyethylene or styrene ethylene butylene styrene.

A PTC composition comprises crystalline polymer and conductive filler. The conductive filler comprises tungsten carbide powder dispersed in the crystalline polymer, and the tungsten carbide powder comprises impurity of less than 7% by weight. The impurity comprises the materials other than tungsten monocarbide.

An electrical device having first and second electrodes and a layer of a conductive composite electrically in contact with the first and second electrodes. The conductive composite is a mixture of a semi-crystalline polymer and a conductive filler, the conductive filler including a plurality of particles containing an inner material including a first metal; and an outer material surrounding the inner material, the outer material including a second metal; and an intermetallic compound formed between the inner material and the outer material. The intermetallic compound has features from the inner material and the outer material. The device can be a circuit protection device. Also provided is a method of making a conductive composite by dry mixing the components.

Surface-mountable conductive polymer devices include a conductive polymer layer between first and second electrodes, on which are disposed first and second insulation layers, respectively. First and second planar conductive terminals are on the second insulation layer. A first cross-conductor connects the second electrode to the first terminal, and is separated from the first electrode by a portion of the first insulation layer. A second cross-conductor connects the first electrode to the second terminal, and is separated from the second electrode by a portion of the second insulation layer. In some embodiments, at least one cross-conductor includes a beveled portion through the first insulation layer to provide enhanced adhesion between the cross-conductor and the first insulation layer, while allowing greater thermal expansion without undue stress. In other embodiments, these advantages are achieved by having at least one cross-conductor in physical contact with a metallized anchor pad on the first insulation layer.

An over-current protection device includes an electrode layer and a heat-sensitive layer. The heat-sensitive layer exhibits a positive temperature coefficient (PTC) characteristic, and is laminated between a top metal layer and a bottom metal layer of the electrode layer. The heat-sensitive layer includes a polymer matrix and a conductive filler. The polymer matrix includes a fluoropolymer. The fluoropolymer has a plurality of spherulites, and the fractal dimension of each spherulite is lower than 12.

Surface-mountable devices include a conductive polymer layer between first and second electrodes, on which are disposed first and second insulation layers, respectively, with first and second planar terminals on the second insulation layer. A first cross-conductor connects the second electrode to the first terminal, and is separated from the first electrode by a portion of the first insulation layer. A second cross-conductor connects the first electrode to the second terminal, and is separated from the second electrode by a portion of the second insulation layer. At least one cross-conductor may include a beveled portion through the first insulation layer. Alternatively, at least one cross-conductor may contact an anchor pad on the first insulation layer, the anchor pad having a small area relative to the areas of the terminals. Enhanced adhesion between the cross-conductor(s) and the first insulation layer is provided, while allowing thermal expansion without excessive stress.

A macromolecule-based conductive composite material and a PTC element. The macromolecule-based conductive composite material comprises: a macromolecule base material, having a volume fraction of the macromolecule base material of 20%-75%; a conductive filler with a core-shell granule structure and dispersed in the macromolecule base material, having a volume fraction of 25%-80%; and a coupling agent, being a titanate coupling agent and accounting for 0%-5% of the volume of the conductive filler. The PTC element prepared by using the macromolecule-based conductive composite material comprises at least two metal electrode plates (12, 12), a macromolecule-based conductive composite material (11) being closely combined with the metal electrode plates (12, 12). The PTC element prepared from the macromolecule-based conductive composite material has the advantages of low room-temperature resistivity, outstanding weather durability, good voltage resistance and good resistor repeatability.

Approaches provided herein include a protection device assembly including multilayer electrodes. In some embodiments, a protection device assembly may include a protection component, a first electrode layer extending along a first main side of the protection component, and a second electrode layer extending along a second main side of the protection component. The protection device assembly may further include a first substrate layer disposed over at least one of: the first electrode layer, and the second electrode layer, a foil layer disposed over the first substrate layer, wherein the foil layer is partially separated from the first electrode layer by the first substrate layer, and a solder pad extending around an end of the protection component and the first substrate layer, wherein the solder pad is in contact with the foil layer.

A positive temperature coefficient (PTC) circuit protection device including a dielectric substrate layer, first and second high resistance layers disposed on a top surface of the substrate layer in a spaced apart relationship to define a gap therebetween, a PTC layer disposed on the top surface of the substrate layer in the gap and in contact with the first and second high resistance layers, a mask layer covering a top surface of the PTC layer and portions of top surfaces of the first and second high resistance layers, an electrically conductive first terminal covering a first longitudinal end of the substrate layer and an outermost end of the first high resistance layer distal from the PTC layer, and an electrically conductive second terminal covering a second longitudinal end of the substrate layer and an outermost end of the second high resistance layer distal from the PTC layer.