An over-current protection device includes a first metal layer, a second metal layer and a heat-sensitive layer laminated therebetween. The heat-sensitive layer exhibits a positive temperature coefficient (PTC) characteristic and includes a first polymer and a conductive filler. The first polymer consists of polyvinylidene difluoride (PVDF), and PVDF exists in different phases such as -PVDF, -PVDF and -PVDF. The total amount of -PVDF, -PVDF and -PVDF is calculated as 100%, and the amount of -PVDF accounts for 33% to 42%.

A composite circuit protection device includes a transistor, a positive temperature coefficient (PTC) component, a first lead pin, a second lead pin and a third lead pin. The transistor includes a drain electrode, a gate electrode and a source electrode. The PTC component includes a first electrode, a second electrode, and a PTC matrix disposed between the first electrode and the second electrode. The second electrode is in contact with the gate electrode of the transistor. The first lead pin is bonded to the drain electrode of the transistor. The second lead pin is bonded to one of the first electrode and the second electrode of the PTC component. The third lead pin is bonded to the source electrode of the transistor.

An over-current protection device includes a first metal layer, a second metal layer and a heat-sensitive layer laminated therebetween. The heat-sensitive layer exhibits a positive temperature coefficient (PTC) characteristic and includes a first polymer and a conductive filler. The first polymer consists of polyvinylidene difluoride (PVDF), and PVDF exists in different phases such as -PVDF, -PVDF and -PVDF. The total amount of -PVDF, -PVDF and -PVDF is calculated as 100%, and the amount of -PVDF accounts for 48% to 55%. The conductive filler has a metal-ceramic compound.

An over-current protection device includes a first metal layer, a second metal layer and a heat-sensitive layer laminated therebetween. The heat-sensitive layer exhibits a positive temperature coefficient (PTC) characteristic and includes a polymer matrix and a first conductive filler. The polymer matrix includes a polyolefin-based polymer and a fluoropolymer. The fluoropolymer has a melt flow index higher than 1.9 g/10 min, and the polyolefin-based polymer and the fluoropolymer together form an interpenetrating polymer network (IPN). The first conductive filler has a metal-ceramic compound dispersed in the polymer matrix.

The present invention relates to a positive temperature coefficient composition comprising a semi-crystalline material, at least one binder, from 0.5 to 9.5% by weight of an electronically conductive material and a solvent. Furthermore, the present invention relates to use of a positive temperature coefficient composition according to the present invention in heating elements and sensors. A positive temperature coefficient composition according to the present invention provides low and stable resistance till self-regulating temperature, which allows fast heating of the heating element. Furthermore, the positive temperature coefficient composition according to the present invention has high PTC ration and therefore, has higher safety and more power can be applied to the heating element.

A novel polymer positive temperature coefficient (PPTC) material, device, and method of fabrication. The PPTC device may include a PPTC body; a first electrode disposed on a first surface of the PPTC body and a second electrode disposed on a second surface of the PPTC body, opposite the first electrode. The PPTC body may include a polymer matrix; and a conductive filler, disposed in the polymer matrix. The conductive filler may include a tungsten carbide component comprising at least 30 volume percent of the PPTC body; and a carbon component, wherein a total volume fraction of the conductive filler comprises between forty volume percent and sixty five volume percent of the PPTC body.

An over-current protection device includes first and second electrode layers and a PTC material layer laminated therebetween. The PTC material layer includes a polymer matrix, and a conductive filler. The polymer matrix has a fluoropolymer. The total volume of the PTC material layer is calculated as 100%, and the fluoropolymer accounts for 47-62% by volume of the PTC material layer. The fluoropolymer has a melt viscosity higher than 3000 Pa.Math.s.

A composite circuit protection device includes a transistor, a positive temperature coefficient (PTC) component, a first lead pin, a second lead pin and a third lead pin. The transistor includes a drain electrode, a gate electrode and a source electrode. The PTC component includes a first electrode, a second electrode, and a PTC matrix disposed between the first electrode and the second electrode. The second electrode is in contact with the gate electrode of the transistor. The first lead pin is bonded to the drain electrode of the transistor. The second lead pin is bonded to one of the first electrode and the second electrode of the PTC component. The third lead pin is bonded to the source electrode of the transistor.

A circuit protection device includes a positive temperature coefficient (PTC) component, an insulating unit, and a device electrode unit. The PTC component includes a PTC layer, a first PTC electrode, and a second PTC electrode. The PTC layer has two side walls that are opposite to each other. The insulating unit is disposed on the PTC component. The device electrode unit is formed on the insulating unit and includes a first device electrode and a second device electrode. The first device electrode is electrically connected to the first PTC electrode and is spaced apart from one of the side walls of the PTC layer. The second device electrode is electrically connected to the second PTC electrode.

A surface-mounted polymer PTC overcurrent protection element having a small package size, comprising a PTC chip, an insulating layer (30), end electrodes (41, 42), and at least one conductive member (60). A dividing gap is designed on a first conductive electrode (21) to form first and second conductive areas (211, 212); the conductive member (60) is arranged at the edge or at least a corner of the first conductive area (211) side of the PTC chip, is used for conducting the first conductive area (211) and a second conductive electrode (22) on the PTC chip, and is not in contact with the end electrodes (41, 42); the main portion comprised in the dividing gap (70) of the first conductive electrode (21) is parallel to the longitudinal direction of the first end electrode (41) and the second end electrode (42).