Human technology continues to grow at an exponential rate. Every few years, major innovations in technology occur. Nevertheless, there are some innovations which continue to be relevant throughout all these years, and the invention of the printed circuit board is sure to be among them.
Basically, printed circuit boards connect the electrical components of most devices together, forming circuits. Due to this, they are similar in function to wires, which are also used in making electric circuits. Their main difference lies in the way they do their jobs. Wires take up too much space, use lots of resources, and become prone to short circuits as they age and their insulation degrades. Printed circuit boards, on the other hand, take up less space and are well protected against short circuits. They can cram many circuits into a tiny space. Since the amount of circuits in a device determines the capability of such a device to handle complex tasks, printed circuit boards are inherently superior when it comes to computing power.
A printed circuit board consists of one or more layers of conductive material supported by an underlying substrate. Copper is abundant, electrically conductive, and corrosion resistant, which is why manufacturers frequently use it in creating printed circuit boards. The circuits are located on the conductive layer. To create the circuits, enough copper is stripped away during production, leaving narrow lines of copper on the surface of the bare substrate. These enable electrical signals to travel to the various components attached on the board.
Another layer, called the soldermask, is present on many circuit boards. This gives the circuit boards their distinctively green color. This layer also protects the copper circuits from pieces of metal or other conductors which might otherwise form short circuits. An additional layer forms symbols or text on the surface of the circuit board, informing manufacturers about the different connections present on the board. This layer, termed the silkscreen layer, typically has a white color.
The substrate, which forms the bulk of the printed circuit board, uses non-conducting materials, usually fiberglass or plastics, to form a physical barrier between adjacent copper circuits. Without them, short circuits would occur and damage the device. The substrate also mechanically supports the other parts of the circuit board. Furthermore, the substrate layer protects more delicate components from any shocks.
The arrangement of the conductive and insulating layers on the circuit board, as well as the number of conducting layers present, determines its type. Roughly three types are available in the market. Circuit boards belonging to the first type are called single-layered boards and contain only one conductive layer. Since they are easier and cheaper to produce but contain fewer circuits, their usage is limited to simple, low-end electronics. Boards in the second type are dubbed double-layered boards and have two conductive layers. Although they are harder to produce, they can carry more circuits and handle more electrical components. They are the most common type of printed circuit board. All other circuit boards are aptly named multi-layered boards. Containing more than two conductive layers, these circuit boards are difficult to manufacture but have the greatest computing power.
For double-layered and multi-layered boards, holes plated with a ring of conductive material are used to connect circuits which belong on different conductive layers. This allows the creation of more complex circuits.
Other components are attached on the printed circuit board. These components, which may include resistors, capacitors, and integrated circuits, employ the network of copper lines on the circuit boards to supply themselves with electricity, modify the electric current, or send signals to other components.