A substrate has a substrate member, which is made of Polymethyl methacrylate (PMMA) or Polycarbonate (PC), having a first side and a second side. On the fist side and the second side of the substrate member provided with an insulating layers respectively, wherein the insulating layers are made of Cyclic Olefins Polymer (COP). The water absorption of COP is less than the water absorption of PMMA and PC to prevent the substrate member from warping while the substrate is heated at a single side.