Abstract: An over-current protection device comprises two metal foils and a positive temperature coefficient (PTC) material layer. The PTC material layer is sandwiched between the two metal foils and comprises plural crystalline polymers with at least one polymer melting point below 115° C., and a non-oxide electrically conductive ceramic powder. The non-oxide electrically conductive ceramic powder exhibits a certain particle size distribution. The PTC material layer has a resistivity below 0.1 ?-cm. The initial resistance of the device is below 20 m?, and the area of the PTC material layer is below 30 mm2. The over-current protection device exhibits a surface temperature below 100° C. under the trip state of over-current protection.

Abstract: The present invention discloses an over-current protection device comprising two metal foils and a positive temperature coefficient (PTC) material layer. The PTC material layer is sandwiched between the two metal foils and contains at least one crystalline polymer, a non-oxide electrically conductive ceramic powder and a non-conductive filler. The non-oxide electrically conductive ceramic powder exhibits a certain particle size distribution. The PTC material layer presents resistivity below 0.1 ?-cm.