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How do Printed Circuit Boards Work?

The technological revolution in modern times has shaped every aspect of how we live – and nothing more so than the tiny, yet vital printed circuit board. It is at the heart of every electronic device and plays a crucial role in just about every industry.

A printed circuit board has electrically conductive pathways, known as “traces”, that link electronic components together. It is one of the most important inventions ever made, with the underlying concept remaining the same, even though the complexity of the boards has evolved over time.

Circuit boards simplify the electrical wiring process by replacing multiple components that were once wired via cable or solder with simpler printed circuit boards.

Printed circuit board

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Where are circuit boards used?

Widely used in the health service in medical imaging systems, monitors, computer systems and many other applications; circuit boards are the basis of all electronics.

They ensure LED lighting operates efficiently and are widespread in consumer electronics. Smartphones, tablets, computers, radios, smartwatches and other devices need PCBs to function. Many home appliances now have circuit boards including microwave ovens, coffee machines and refrigerators.

Industrial equipment in the 21st century requires technology that uses printed circuit boards, while automotive manufacturers increasingly use electronic components in their vehicles. The aerospace industry relies on PCBs for power supplies, communications equipment and monitoring equipment, such as accelerometers and pressure sensors.

All kinds of marine vessels use PCBs, including navigation systems and communication systems. The safety and security industry uses them for applications such as CCTV cameras and smoke detectors.

The telecommunications industry couldn’t operate without printed circuit boards, while a multitude of military and defence applications also rely on them.

It would be hard to identify a modern-day industry that doesn’t need PCBs to function.


What are the different types of PCBs?

Over time, circuit boards have become smaller, yet more sophisticated and complex, some having 30 or more layers. Some layers have specialised functions such as providing power or enhancing electronic signals.

These components can range from a simple transistor to a complex microprocessor – an integrated circuit with millions of transistors. The traces are kept short to prevent energy loss. Built on a copper-coated flat surface, the circuit boards provide the required conductive pathways.

There are two main types of PCB: single-sided and double-sided. Found in almost every type of electronic circuitry, single-sided PCBs are most commonly used. Double-sided have printed circuit boards on both sides and they can be used for more complex circuitry. Various other designs include multi-layer, rigid, high-frequency, aluminium-backed PCBs and more.

Flexi circuits are like circuit boards. Manufactured from a more flexible material, compared with other variants of printed circuit boards; they are used in small assemblies, often in interconnections with a simple electronic device. Extremely flexible, these PCBs can withstand high temperatures.

Printed Circuit Board

© Sellectronics

Along with flex rigid PCBs, the flexi circuits are the hardest to assemble and manufacture. A hybrid of rigid and flexible printed circuit boards; they provide the sturdiness and durability of a rigid PCB, combined with the adaptability of flexi circuits. With a rigid core, combined with a flexible polyimide film; they are used for certain technological applications that require both durability and flexibility.

Each with their own purpose; various different PCB designs include multi-layer, rigid, high-frequency, aluminium-backed and more. What they all have in common is the ability to provide a simple way to add and replace components without hassle in the event of a repair being needed.


How do PCBs work?

The principle of continuity is the first law of electricity. If there is one single wire, the electricity follows the path of least resistance, so it will move through the whole wire, leaving at the other end. This is known as a continuous or fixed circuit.

More complicated circuits have more than one path for the electricity to pass through. The laws of electricity make it possible to restrict the flow of electricity in any circuit to enable only a specific amount to be transferred.

The wire must carry the correct amount in order to create a continuous short circuit. The process is known as “voltage division”. Manufacturers can also place impurities within the metal as resistors. They permit the voltage to pass to a chosen point. Then, the impurities prevent the electricity from proceeding to the end of the wire. This is known as creating a “closed” circuit, when the current can change direction, but the voltage remains the same.

Circuits can carry very large amounts of power, as dividing the voltage makes it safe. Only a part of the power is going through the wire at any given time. Any breaks in the surface mean no power reaches the load. With all types of circuit, there’s a finite amount of current.

If the loop of wire is correctly formed, the current will flow continuously through the loop. The energy can be converted into heat and other utilities, so the wire can retain large amounts of energy.

Today, PCBs have become much smaller and lighter, with a higher layer count, creating multi-layered, flexible circuit designs that are extremely functional and efficient in electronic devices, with lower production costs.


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