Copper clad boards photo

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.
The copper layer is coated with a photo resist (light sensitive layer), so that the PCB design can be transferred photographically. A positive image of the design is placed on the board, after which  it is subjected to UV light for a few minutes.The image is then deveoloped in a basic solution. After this, the design remains on the board, which is ready for etching.