What is a printed circuit board?

Before we get into the details of the different and most common components that circuit boards are made of, it is essential to first establish what a printed circuit board (PCB) is and explain its functionality. 

A PCB is a circuit board that connects the electrical components of a device. In order for an electronic device like your mobile phone, computer or even light switch, to function, there must be a level of interconnectivity between the electrical components, which is what the PCB provides with layers of copper circuitry.

So what components are printed circuit boards made of?

PCBs are made up of a variety of different electrical components, each vital to the functionality of the device to which it will belong. These PCB components include transistors, fuses, resistors and capacitors, which all play their part to ensure we have a smooth-running device – if one of these components fails, the entire PCB will fail to work and thus affect the functionality of the product itself.

But what are the most common components, and what do they do? In this article we will outline seven of the most important and common PCB assembly components and look at why they are so important. 

1. Resistors

Resistors are one of the most crucial and common components in a PCB. They transmit an electric current in order to produce a voltage and dissipate electric power as heat. They can come in a range of different materials and are colour coded in order to determine their resistance value.

2. Transistors

A transistor is simply an amplifier used to switch or control the electronic signals in a board. Transistors have several different variations but the most common is the bipolar transistor, which consists of three pins – the base, the collector and the emitter. 

3. Capacitors

Capacitors are the second most common component after resistors. Capacitors hold electrical charge within the board and release it whenever more power is needed elsewhere in the circuit, typically by collecting opposite charges on two conductive layers, separated by an insulating material.

4. Inductors

Inductors are similar in their nature to capacitors, in that they store energy in the form of a magnetic field when current flows through them. They are often used to block signals within the board, such as interference from another electronic device or piece of equipment.

5. Transformers

Transformers are commonly used in order to transfer the electrical energy from one circuit to another by an increase, or decrease, in voltage.

6. Diodes

A diode is a device in the circuit that allows the electrical current to flow in one direction, but not the other. This can be used in order to block current from flowing in the wrong direction, which could damage the board and the device. The most popular diode is the LED (Light Emitting Diode), which is of course used to emit light. 

7. Sensors

These are devices that detect changes in environmental conditions and generate an electrical signal that corresponds to the change it has detected, which is then sent on to the other components in the circuit board. Sensors convert a physical element such as light motion, air quality, or sound into electrical energy like a transducer.