A substrate of the present invention is provided with a plurality of parallel-arranged functional sections. First and second connecting sections are provided on both ends of the functional sections. Every two adjacent functional sections are separable from one another and are respectively connected with different connecting sections so that the substrate can be separated into two daughter substrates having identical areas. The two daughter substrates of the substrate can be processed simultaneously before separated from each other, thus saving the processing time. When used by a user, one daughter substrate can be used independently as a light source or the two daughter substrates can be used opposite to each other so that the functional sections of the two daughter substrates are staggered.