Surface mountable over-current protection device

摘要

A surface mountable over-current protection device having upper and lower surfaces comprises a PTC device, first and second electrodes, and first and second circuits. The PTC device comprises a PTC material layer and first and second conductive layers. The PTC material layer is disposed between the conductive layers and comprises crystalline polymer and conductive filler dispersed therein. The first electrode comprises a pair of first metal foils, whereas the second electrode comprises a pair of second metal foils. The first circuit connects the first electrode and conductive layer, and has a first planar line extending horizontally. The second circuit connects the second electrode and conductive layer, and has a second planar line extending horizontally. At least one of the planar lines has a thermal resistance sufficient to mitigate heat dissipation by which the over-current protection device undergoes a test at 25° C. and 8 amperes can trip within 60 seconds.

主权项

1. A surface-mountable over-current protection device being a substantially rectangular cuboid having upper and lower surfaces, a first lateral surface, a second lateral surface, a first end surface and a second end surface, the first and second lateral surfaces and the first and second end surfaces interconnecting the upper and lower surfaces; the over-current protection device comprising:
a PTC device comprising a PTC material layer, a first conductive layer and a second conductive layer, the PTC material layer being disposed between the first and second conductive layers, and comprising crystalline polymer and conductive filler dispersed therein; a first electrode comprising a pair of first metal foils formed at the upper and lower surfaces; a second electrode comprising a pair of second metal foils formed at the upper and lower surfaces; a first circuit electrically connecting the first electrode and the first conductive layer and comprising a first planar line extending horizontally and a first conductive connecting member extending vertically; and a second circuit electrically connecting the second electrode and the second conductive layer and comprising a second planar line extending horizontally and a second conductive connecting member extending vertically; wherein at least one of the first planar line and the second planar line has a thermal resistance sufficient to mitigate heat dissipation, thereby the over-current protection device undergoes a test at 25° C. and 8 amperes can trip within 60 seconds.