Printed circuits are a method of interconnecting electronics components without discrete wires. Printed circuits were first used commercially in the 1950s. Printed circuit technology uses photolithography or mechanical deposition to attach conductive layers to an insulating substrate. A printed circuit is also called a printed circuit board. Printed circuits can be multi-layer, meaning that multiple coplanar layers of interconnecting wires are laminated together. Layers may be connected together through electroplated or mechanically inserted interconnects called "vias". Single-layer boards are least expensive and are commonly employed in low-cost consumer products. Multi-layer boards are needed for complex digital circuits such as computers. Ground and power planes are rectangular sheets of conductor that occupy entire layers to provide better power distribution in multilayer circuit boards as well as thermal distribution of heat generated by the components on the board. Components leads are inserted in "holes" or mounted on the surface "pads" and electrically and mechanically fixed to the board with a metal solder. A solder mask keeps islands of solder from running together and protects conductor layers from abrasion. A silkscreen legend on the top or bottom surface of the board provides readable information about component part numbers and placement that aids in manufacturing and repair.
Printed Circuit Manufacturing Guides