Copper clad boards
Copper laminates are sheets of insulating material, covered with a very thin layer of copper, used to manufacture circuit boards. The copper layer is etched, leaving traces and pads to conduct electricity and hold components.
The laminate usually consists of phenolic paper (pertinax/FR2) or fibreglass (FR4) and is approx. 1.5mm thick. The copper layer is often around 35um (35/1000mm), but can also be thicker or thinner. The thicker ones are meant for high-current uses.