Printed circuit board

A printed circuit board, or PCB, is the flat board that electronic parts are mounted on. Instead of loose wires, it has flat copper paths, called traces, bonded to its surface and often to layers inside. The traces connect the parts' pins exactly as the circuit design requires.

The base is FR-4 laminate, a stiff sheet of glass cloth and epoxy, supplied with thin copper foil bonded to both sides. A light-sensitive film is laid over the copper and exposed to the circuit pattern with ultraviolet light. After developing, the film protects the copper where traces should be, and chemicals etch away the rest. For multilayer boards, etched layers are stacked with sheets of resin-soaked glass cloth and pressed together under heat. Holes are drilled and their walls plated with copper to link the layers. Then solder mask is coated over everything except the pads where parts will be soldered, and labels are printed on top.

PCBs are the base of the main board, timing controller board, power supply board, LED strip, remote control and Wi-Fi and Bluetooth module. Their designs differ a lot with the job: some LED strips use aluminum-backed boards to shed heat, and simple power boards may use cheaper paper-based laminates.