2. The base material is an insulating board composed of polymer synthetic resin and reinforcing material; The surface of the substrate is covered with a layer of pure copper foil with high conductivity and good weldability, usually with a thickness of 35 ~ 50/Ma; A copper clad laminate with copper foil covering one side of the substrate is called a single-sided copper clad laminate, and a copper clad laminate with copper foil covering both sides of the substrate is called a double-sided copper clad laminate. Whether the copper foil can be firmly coated on the substrate is completed by adhesive. The commonly used copper clad laminates are 1.0mm, 1.5mm and 2.0mm. ..