A printed circuit board or PCB is an electronic board manufactured by printing layers of copper onto a substrate of fiberglass or epoxy-coated paper.
A printed circuit board can be made to be the base of an electronic device, or it can be mounted in a chassis (a plastic or metal case) and soldered to other components using tinning, through-hole plating, surface mount technology (SMT), or leaded connection techniques. A printed circuit board can also function as a part of a larger system that includes mechanical parts such as switches, plugs, and sockets. The term “printed circuit” can be applied to an entire printed circuit board or just the surface layer containing components and traces.
The primary benefit provided by a printed circuit board is that it connects electrical components electrically via conductive tracks, known as traces and pads on one side of the board, to form an electrical circuit. Traces are usually etched onto copper sheets called laminate, and then covered with a protective coating; however, they may also be formed using thin wires bonded to the laminate through holes in the laminate and/or via other processes such as photolithography. In addition to conductive traces, non-conductive features may also be present on the substrate such as insulating barriers.
Different types of PCBs
Printed circuit boards (PCBs) are the foundation of modern electronics. They are what allow us to shrink down complex electronics into small devices like phones, computers and even vehicles.
There are a variety of different types of printed circuit boards, from simple single-sided boards to complicated multi-layer boards with tiny components that can be hard to spot with the naked eye.
The most common type is the double-sided board, which has copper traces on both sides. This allows for easier routing and more flexible layout options. Double-sided PCBs also have plated through holes so that through-hole components can be soldered onto both sides of the board.
Other common types include single-sided PCBs (sometimes called ‘single layer’) and multilayer PCBs. Multilayer PCBs have multiple layers of copper traces sandwiched between layers of fiberglass laminate material that’s been etched to leave copper only where it’s needed for electrical connections between traces on different layers of the board.
History of printed circuit board or PCB
The history of the printed circuit board is intertwined with the history of electronics and computers. The first PCBs were developed in the late 19th century to replace mechanical components with electrical components. PCBs were used in telegraph equipment and telephone switches to replace relays, which had proved unreliable under certain conditions.
The invention of the transistor in 1947 allowed for much smaller electronic devices. Transistors could be added to existing circuit boards, but they lacked the flexibility of a printed circuit board. As integrated circuits became more powerful and complex, they required an entirely new type of printed circuit board design. Integrated circuits require many more connections than relays or transistors alone can provide.
Electrical engineer Paul Eisler invented the first PCB in 1962 while working at IBM’s research center in East Fishkill, New York. His design included copper lines on a sheet of plastic material that could be etched using acid or other chemicals to create pathways between components. A layer of lacquer was applied over this copper so that solder could be used to connect components, creating circuits similar to those found on today’s printed circuit boards.
The first commercial use of this method was during World War II when it was used to make radar units for aircraft carriers and submarines. After World War II, Eisler began working on multi-layer versions of PCBs that allowed more complex circuits to be built into one device.
Later, PCBs were in telephones and other communication equipment used by AT&T. By 1959, printed circuit boards were being produced on a mass scale by companies like Motorola and Bell Labs.