How to Identify Common PCB Components

Overview: The bare PCB board does not function alone, it is more like a carrier. Engineers chemically etched out tracks on the bare board, which worked like wires. It will provide a bridge to the different PCB components on the board by means of electrical connections and make them functional. FS Tech will identify these common electronic components with you in this article.

Common components on PCBA boards

Without any respect of any type of PCB type, electronic components can only be placed on  either the top layer or the bottom layer of PCB. But first, we have to know about components.  Electronic Components are meant to be interlinked through tracks on PCBs’ conductive layer to develop electronic circuit which performs desired function for example oscillator, amplifier,  transmitter, receiver, and wireless.  

Following are the main electronic components used more frequently from the simplest single  layer PCB to complex multilayer PCB. 


One of the most common components, its main function is to control the amount of current in the circuit. For example: limiting the current before using the LED to protect the LED from high currents that could cause burnout. The picture below shows Resistor symbols:

Resistor symbols


When people talk about the function of capacitors, they immediately think of charging and discharging. This is only its most basic role, but based on this basic role, many circuit phenomena can be realized, such as: in a motor, it can produce violent vibration; in a camera, a capacitor can discharge instantaneously with high energy. Commonly used capacitors in our life include phase-shift capacitors, electric heating capacitors, coupling capacitors, etc. Different types of capacitors are used in different fields and have different functions. The following figure shows the capacitor symbol:

Capacitor symbols


Transistors are indispensable PCB components in the electronics manufacturing industry, and their numbers are very large. We can simply divide it into triode, diode, thyristor, etc. It has a variety of functions such as detection, rectification, amplification, switching, voltage regulation, signal modulation and so on. The figure below shows the transistor symbol:

Transistor symbol


  • Diodes are the most common type of transistors, is used to direct current in only direction, mostly used for reverse polarity protection  for reverse polarity circuits.
  • The triode increases the amplifier function on this basis.
  • The transistors can perform logic operations after splicing.

Classification of PCB components

Classified by component properties

In order to facilitate management, we generally further classify electronic components into two types based on various factors like power  gain, functions, nature of the source, and controlling the flow of current. 

Active Components

These components provide power to the circuit instead of utilizing it that’s why they are called  active components and the energy produced is in the form of voltage and current. Active  components are also called energy donors. They utilize energy from an external source to perform  their function, 

Examples of active components include transistors, Diodes, and Integrated circuits (IC). 

Passive Components

Passive electronic components utilize the energy that active components provide to the circuit.  These components just store energy and are unable to provide energy like active components.  Passive Components are also called Energy acceptors. 

Examples include resistors, Capacitor, and Inductor.

Categorize PCB Components by Package

If you carefully observe the PCBA board in your hand, you can find that the electronic components on the same circuit board use different packaging processes. In simple terms, one is directly inserted into the hole in the PCB board, and the other is soldered to the PCB board. Therefore, PCB components can be divided into two categories according to their packaging methods.

Through-Hole Component

Almost every component in electronics has a through-hole  package. These packages have long enough pins to get passed from the top layer to the  bottom and get soldered on the bottom layer with PCB. They are also called multilayer  packages. For such a package, routing can be done on either the top layer or bottom layer, or other multi-layers of PCB. 

Surface Mount Device (SMD)

As the name suggests these are components mounted on  only one side of the PCB, due to this reason their routing is also done on that same side or  can be shifted to another layer using vias in PCB. Almost every electronic component also  comes in this package. 

Electronic component either through-hole or SMD is used according to need. Their working  principle and function resemble but differ in size and soldering methodology.  

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