Printed circuit board (PCB). Computer artwork of the PCB from a motherboard (main circuit board) of a personal computer (PC). PCBs are non-conductive sheets laminated with copper pathways, or traces, that are used to mechanically support and electrically connect electronic components. Motherboard components include transistors, diodes, resistors, capacitors and inductors. Motherboards contain the main processing parts of a computer system, including the microprocessor, memory and connecting wires to other parts of the computer.