A printed circuit board (PCB) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non-conductive substrate. PCB's can be single sided (one copper layer), double sided (two copper layers) or multi-layer. Conductor on different layers are connected with plated-through holes called vias. Adva
nced PCB's may contain components - capacitors, resistors or active devices - embedded in the substrate. Printed circuit boards are used in all but the simplest electronic products. Alternatives to PCBs include wire wrap and point-to-point construction. PCBs are more costly to design but allow automated manufacturing and assembly. Products are then faster and cheaper to manufacture, and potentially more reliable. Much of the electronics industry's PCB design, assembly, and quality control follows standards published by the IPC organization. When the board has only copper connections and no embedded components it is more correctly called a printed wiring board (PWB) or etched wiring board. Although more accurate, the term printed wiring board has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly (PCA), printed circuit board assembly or PCB assembly (PCBA). The IPC preferred term for assembled boards is circuit card assembly (CCA), [1] for assembled backplanes it is backplane assemblies. The term PCB is used informally both for bare and assembled boards.
