A light source having a flexible substrate and a plurality of dies having LEDs is disclosed. The light source can be conveniently utilized to provide an extended light source by bonding the light source to a suitable light pipe. The substrate is divided into first and second regions. The dies are bonded to the substrate in a first region. A portion of the surface of the substrate in the second region is reflective. The substrate is bent such that the second region forms a reflector that reflects light that would otherwise be emitted in a non-useful direction to a more useful direction. The substrate can be constructed from a three layer flexible circuit carrier in which the dies are mounted on a bottom metal layer to provide an improved thermal path for heat generated in the dies.