Automated assembly equipment typically requires that the board being assembled move along a track. The actual board sits on two chains on either side of the track. As the chain moves along the assembly line the board is moved along with it from station to station. If components are close to the board edge they may interfere with how the board sits on the chain. Hence the need for rails.
Rails are extensions of the pcb that are attached and later removed after the board is assembled. Rails are added for handling purposes and to provide clearance for components that may be close to the board edge. It is common practice for anyone that assembles printed circuit boards with components to (more…)