What is a printed circuit board, aka PCB? It’s an electronic…board made of copper conductors and non-conductive materials used to mount electronic components and create electrical connections between them. It can have from one to twelve layers, depending on the complexity of the electronic device that it’s installed in. Do you want to learn more about PCBs, their types, and examples of usage? Then keep reading this article!

What Is a PCB? Definition

A printed circuit board is the base for surface-mounted and socketed components in electronics – it both supports them physically and enables wiring them together. It is mostly made of non-conductive material, often fiberglass or composite epoxy combined with copper conductors. Despite being mostly associated with computers, PCBs can be found in numerous other electronics, including embedded systems.

PCB owes its name to the way in which it is produced. The process starts by printing the PCB design with a plotter printer to make a film of the desired printed circuit board, which in fact, is simply a negative photo of the design. This is color-coded with two types of ink: black and clear. The black ink represents the conductor sections of the board on the inside layers, while the non-conductive areas on the outside layers; the clear ink does the same thing but the other way around – represents non-conductive parts on the inside and conductive on the outside layers.

When the PCB design is printed to the laminate material, a copper foil is added. The panels are then covered in resist – photo-sensitive film – which enables engineers to match the photos of the blueprint. Then, the whole board is exposed to UV light, which hardens the resist in areas where copper is meant to be preserved. In other places, the black ink prevents that from happening and stops the UV rays. The board is then washed with an alkaline solution to remove any resits apart from the hardened one. Finally, the board is etched – the necessary copper conductors are covered, and the rest of the material is exposed to a chemical that removes it from the PCB. Bear in mind that it’s the process for single-layered printed circuit boards – it gets more complicated in complex designs.

What Are the Types of PCBs?

Apart from the distinction based purely on the number of layers, it is possible to categorize printed circuit boards based on the way in which they are constructed or the materials used. The most common classification includes:

  • Single-sided PCBs – These printed circuit boards have components mounted only on one side. The other is usually fully made of copper and serves as the ground. They are inexpensive, though often a bit larger than the other types. Nevertheless, due to the ease of production and low costs, they are among the most widely used PCBs – you’ll find them in vending machines, camera systems, calculators, printers, LED lighting, and many more devices.
  • Double-sided PCBs – Since there are single-sided PCBs, it’s only natural that there are double-sided ones as well. What characterizes them is that they are somehow synonymous with double-layered boards – each side is classified as a different layer. However, they are a bit more expensive in production, so they are not used as often as single-sided ones. But you will still find them in devices such as cell phones or amplifiers.
  • Multilayer PCBs – We need to mention them here, as they are a category of their own due to their complexity. However, multilayer printed circuit boards also fall into other groups: for instance, they can be either single- or double-sided. It’s also worth mentioning that they usually take less space than single-layer boards and are most commonly used in PCs, tablets, or medical equipment.
  • Rigid PCBs – Printed circuit boards may also be divided based on their flexibility, with rigid PCBs being the least flexible. These boards are lightweight and quite cost-effective. Typically, you will find them in X-ray machines or GPS equipment.
  • Flex PCBs – On the other side of the scale are flexible or flex PCBs. These can be twisted or folded without any damage and are most commonly made of conductive polyester film. Where are they used? In embedded systems in automobiles, medical devices, and cameras.
  • Rigid-flex PCBs – In between flex and rigid PCBs there are the rigid-flex ones. They are designed and built in 3D and are modified to fit the particular device they will be installed in. They don’t require connectors, so they are lightweight. You will find them mostly in medical or aerospace devices.
  • Ceramic PCBs – We also need to mention ceramic PCBs, a fairly rare but crucial type of board. They are used in devices that require high thermal conductivity, as these boards often offer even 20x higher thermal conductivity than other PCBs. However, they are expensive and delicate; therefore, they are now only applied to devices in which thermal insulation and conductivity are a must.

The Takeaway

Let’s summarize. What is a printed circuit board (PCB)? It’s the board in electronic devices which holds the components together and connects the wiring. It’s made from a printed blueprint, hence its name. PCBs come in many shapes and sizes: they can be single- or multi-layered, single- or double-sided, flexible or rigid. Which ones are the best? It all depends on the device that you wish to install them in.

Do you need a printed circuit board for your project? Then check our custom PCB design service and see how we can help you!