Patent ID: 8322882

Claim:
A precursor substrate comprising: a flexible printed circuit board having a bottom heat-conducting layer, an insulating layer, and a circuit layer, said insulating layer and said circuit layer comprising a plurality of openings that expose a top surface of said heat-conducting layer, and said circuit layer comprising a plurality of electrical conductors; a plurality of dies bonded to said heat-conducting layer in a corresponding plurality of said openings, each die comprising an LED that is electrically connected to one of said electrical conductors; and a separation ridge extending above said circuit layer and said dies, wherein said separation ridge is configured such that said precursor substrate can be rolled up in a predetermined direction to form a plurality of coils such that said separation ridge prevents said LEDs and any structures constructed above said LEDs, except said separation ridge, from contacting said bottom heat-conducting layer of said flexible printed circuit board on an adjacent layer in said coil.