Printed Circuit Boards

PCBs

PCBs, or printed circuit boards, are a key staple of modern electrical engineering. They can be found in almost every type of electronic device we use today. In fact they’re now so ubiquitous, it’d be much more difficult to list modern tech gadgets that don’t feature some form of PCB than those that do.

This quick introductory page covers the very basics of what printed circuit boards are, and how they’re put together. We’ll also outline the various services available through our state-of-the-art PCB design and manufacturing setup here at ABL Circuits.

What is a PCB?

In very simple terms, a printed circuit board is essentially a neater, more compact and more reliable alternative to the older standard of multi-wire circuits. Before PCBs were as widely used as they are now, components in any electronic device relied on full point-to-point wiring for their interconnections.

Not only is this a labour-intensive and time consuming approach to circuit building, it’s also much more prone to various instabilities and points of failure. Shorts and faulty connections are risks very much inherent to those older circuit design standards, and the likelihood of encountering such issues only increases with device usage and age.

Advantages of a PCB

Printed circuit boards eliminate the need for this external point-to-point wiring, instead using etched conductive traces on a solid substrate to form the necessary connections. (For that reason, you might also see PCBs referred to as ‘printed wiring cards’, ‘wiring boards’, or similar.) The components are solder-mounted to this substrate, which has all the required connections for a given circuit already mapped out and etched in place.

PCBs offer a durable, efficient and highly customisable way to create reliable connections between multiple fixed components. Their widespread adoption has had a huge impact in the modern tech world, enabling drastic reductions in both the size and assembly costs of countless electronic products on today’s market.

For more background on the history and function of printed circuit boards, see our dedicated articles What is a PCB? and How do Printed Circuit Boards Work?

How are PCBs made and assembled?

PCB boards are usually assembled from multi-layered sheets of varying materials, some conductive and others insulating. You can think of their basic structure as being a little like a lasagne, layer cake or sandwich.

Fibreglass is typically used for the non-conductive or dielectric layers, giving the board its rigidness and durability. (Other types of PCBs, including more flexible constructions, are also an option for certain applications). These layers form the ‘core’ of the board, and their role is both structural and insulating.

Conductive and masking layers

Between and around these non-conductive materials are placed one or more conductive layers, usually made from thin sheets of copper foil. They’re normally affixed to one or both sides of a fibreglass substrate, using adhesive and heat. These copper layers are what enable the etched traces – the connective paths – on a finished PCB to carry current and voltage around the board, linking components in a completed circuit.

The outer faces of the board will usually feature a layer known as the solder mask. This is commonly placed over any exposed copper sheeting to prevent unwanted contact with nearby items or PCB components, which would cause a short. The solder mask can also have circuit details and other graphics printed onto it, often providing users with information about the layout of attached components. It can also be useful for aesthetic design and branding purposes. For more detailed information, see our pages on PCB Layers Explained, PCB Assembly, and the PCB Manufacturing Process.