An illumination assembly includes a substrate, a wiring structure, a reflecting layer and a plurality of light-emitting diodes. The wiring structure is formed on a part of the substrate, and includes a catalyst layer covering the part of the substrate, and a conducting layer formed on the catalyst layer. The reflecting layer is formed on another part of the substrate that is exposed from the wiring structure. The light-emitting diodes are disposed on the wiring structure and are electrically connected to the wiring structure.