Electronics are an integral part of our daily lives. Everything from our smartphones to our cars contains electronic components. These electronic devices include printed circuit boards, also known as PCBs. Most people recognize printed circuit boards when they see them, so let's define them simply: they are small green chips and copper pieces covered with lines that we find in electronic devices, allowing current to pass between small components. To complicate circuits, thin the paths, and take precautions against oxidation, copper paths are covered with a special paint called solder mask. This insulating material consists of a glass-epoxy mixture, known these days as fiberglass.