OVER-CURRENT PROTECTION DEVICE

摘要

An over-current protection device includes two metal foils and a PTC material layer laminated therebetween. The PTC material layer has a volumetric resistivity between about 0.07 Ω-cm and 0.45 Ω-cm. The PTC material layer comprises a crystalline polymer and first and second conductive fillers dispersed therein. The first conductive filler is carbon black powder. The second conductive filler is selected from the group consisting of metal powder and conductive ceramic powder and has a volumetric resistivity less than 0.1 Ω-cm. The weight ratio of the second conductive filler to the first conductive filler is less than 4. The resistance jump R300/Ri of the over-current protection device is in the range from 1.5 to 5, where Ri is an initial resistance and R300 is a resistance after tripping 300 times.

主权项

1. An over-current protection device, comprising:
two metal foils; and a PTC material layer laminated between the two metal foils and having a volumetric resistivity ranging from 0.07 to 0.45 Ω-cm, the PTC material layer comprising:
at least one crystalline polymer;a first conductive filler being a carbon black powder;a second conductive filler comprising at least one of metal powder, conductive ceramic powder or mixture thereof, the second conductive filler having a particle size ranging from 0.1 to 50 μm, and a volumetric resistivity less than 0.1 Ω-cm; wherein the first and second conductive fillers are dispersed in the crystalline polymer, and a weight ratio of the second conductive filler divided by the first conductive filler is less than 4; wherein resistance jump R300/Ri of the over-current protection device is in the range of 1.5 to 5; Ri is an initial resistance and R300 is a resistance of the over-current protection device after tripping 300 times.