Abstract: A backlight unit may be used to produce backlight illumination for a display. The backlight unit may have a row of light-emitting diodes that are mounted on a flexible printed circuit and that emit light into a light guide layer. The backlight unit may include a chassis that extends around the periphery of the light guide layer. The chassis may have a first portion that is mounted on the flexible printed circuit adjacent to the light-emitting diodes and a second portion that extends over the light-emitting diodes. A heat spreading layer may be attached to a reflector layer and the flexible printed circuit. The heat spreading layer may have a width that is less than the width of the reflector layer. Adhesive patches may attach the light guide layer to the flexible printed circuit. A patterned adhesive layer may be formed over the light-emitting diodes and the light guide layer.