A method of making a light active sheet. A bottom substrate having an
electrically conductive surface is provided. A hotmelt adhesive sheet is
provided. Light active semiconductor elements, such as LED die, are
embedded in the hotmelt adhesive sheet. The LED die each have a top
electrode and a bottom electrode. A top substrate is provided having a
conductive layer. The hotmelt adhesive sheet with the embedded LED die is
inserted between the electrically conductive surface and the conductive
layer to form a lamination. The lamination is run through a heated
pressure roller system to melt the hotmelt adhesive sheet and
electrically insulate and bind the top substrate to the bottom substrate.
As the hotmelt sheet is softened, the LED die breakthrough so that the
top electrode comes into electrical contact with the conductive layer of
the top substrate and the bottom electrode comes into electrical contact
with the electrically conductive surface of the bottom substrate. Thus,
the p and n sides of each LED die are automatically connected to the top
conductive layer and the bottom conductive surface. Each LED die is
encapsulated and secured between the substrates in the flexible, hotmelt
adhesive sheet layer. The bottom substrate, the hotmelt adhesive (with
the embedded LED die) and the top substrate can be provided as rolls of
material. The rolls are brought together in a continuous roll fabrication
process, resulting in a flexible sheet of lighting material.