Various embodiments of a lighting module are described. In one aspect, a lighting module comprises a metal support, a circuit board, and a plurality of light emitting diodes. The metal support has a recess, sidewalls, and a plurality of holes on the sidewalls. The circuit board is fastened on a bottom portion of the recess of the metal support and has two long sides, two short sides, and a respective plurality of flanges on each of the two long sides. The flanges are inserted into the holes of the metal support to compact the circuit board and the metal support. The light emitting diodes are disposed on the circuit board.