A surface-mountable multi-layer electrical circuit protection device with an active element between PPTC layers

摘要

A surface-mountable electrical circuit protection device (10) includes layers defining a first polymer positive temperature coefficient (PPTC) resistive element (16), a second PPTC resistive element (18), and at least one heat-generating electrical component (20) such as a planar zener diode chip positioned between, and in thermal contact with, the first and second PPTC elements, such that an electrical current above a threshold level passing through the component causes the component to heat, the heat being transferred to the PPTC resistive elements and tripping at least one, and preferably both of the first or second PPTC elements to a high resistance state. A series of edge-formed terminal electrodes (22, 24, 26) enable surface-mount connection of the first and second PPTC elements and the electrical component to an electrical circuit substrate, such as a printed circuit board. A method for making the device is also disclosed.