printed circuit board (PCB) A substrate of dielectric material on which a printed circuit, silicon chips, and other components are mounted, and to which connectors are affixed so that the board can plug into a system chassis.A PCB serves a defined purpose. In telecommunications systems, for example, a PCB may provide the physical and logical interface to one or more digital or analog lines or trunks, may provide voice mail service, or may provide call processing logic. See also printed circuit. |