How do Circuit Boards Work

How do Circuit Boards Work?

Whatever electronic equipment or device you are using, there is likely to be a circuit board inside. Most of us use our equipment or device without any thoughts or considerations about what lies under the hood, or how the computer circuit board works. In this blog, Rush PCB UK explains the basics of the circuit board or printed circuit board (PCB), the components on it and their functioning, to give you a better idea of the PCB electronics you are using regularly.

You can consider the electronic circuit board as the heart of an equipment. Basically, the simple circuit board is made of glass fibers with copper tracks and pads on one or both sides. The copper tracks act as conductors of electricity between tiny PCB components mounted and anchored on pads on the board. If you look closely, a grey-colored material known as solder anchors the components in place.

circuit board

PCB Construction

A glass fiber board with copper tracks on one side forms the PCB construction. A slightly more complex type of PCB electronics can have copper tracks on both sides, while still more complex boards can consist of multiple layers, with copper tracks on each layer.

A designer uses a computer and a special program like a PCB CAD for designing the PCB electronics. Depending on the complexity, the PC-Board may be single-, double-, or multi-layered. Once complete, the designer outputs the entire design in the form of a standard file format, commonly, the Gerber format. The designer sends the Gerber file to the PCB manufacturer.

The manufacturer fabricates the printed circuit board design following the Gerber files. They build the PCB in layers with copper traces on each layer. Vias make the interconnections between the layers. A green mask covers the two outermost layers, thereby insulating and protecting the copper from tarnishing. The pads remain exposed as they are necessary for mounting the components. However, a layer of surface finish protects them from tarnishing, until soldering. To help and guide operators mounting components, a silkscreen printing displays the part number of each component in white.

Electronic Components

A multitude of circuit board components are available for use on PCBs, depending on their individual functions. Some of the most circuit board parts are:

Switch: Allows two circuits to interconnect electrically or remain isolated. Once interconnected, a switch allows current to flow.

Battery: Supplies the circuit with electrical energy at a defined voltage level.

Resistor: Controls the amount of current flow in a circuit by offering electrical resistance.

Capacitor: These components store and release charge as necessary

Inductor: These also store and release charge, but in an opposite manner to that by capacitors.

Diodes: These components allow current to flow only in one direction, blocking it in the other.

LEDs: These are diodes that can emit light in many colors.

Transistors: Active components with ability to amplify charge

ICs: Integrated Circuits are active components with multiple functionalities.

PCB Assembly

A PCB assembly consists of mounting and anchoring circuit parts on the PCB, with machines doing most of the work. A solder paste dispensing machine places small amounts of solder paste on the pads of the PCB. Next, a pick-and-place machine takes the surface mount components from reels and places them at specific places on the PCB. This combination of components and PCB then passes through a reflow oven where heat melts the solder paste and anchors the components on the PCB. After testing for shorts and opens, the PCB assembly is ready for use in a device.


We, at Rush PCB UK, have presented only a very brief overview of PCB circuits and how do circuit boards work with components. Although the basic principles remain the same, the complexity increases with the size and number of layers of a PCB, and the type of components it uses.

Call Rush PCB today or visit our website for all your PCB requirements.