What is PCB? Full Form, Types, Design, Applications

The full form of PCB is Printed Circuit Board. In modern electronics industries, the applications and uses of PCB are very much. Every electronic device, in fact, some electrical devices also have printed circuit boards as their internal parts. PCB holds the electrical or electronic components, connects them together, and provides physical support. In this article, we are going to know about the PCB from basics to advanced. Also, we will know about the different types of PCBs, their applications and their advantages.

What is PCB?

PCB is a thin board made up of different types of non-conductive substrate or laminated materials, fibreglass, and composite epoxy. PCB gives physical support to the electronic components by holding their base or terminals and also makes electrical contact between them by laminated conductive copper tracks and pads. So, the main function of a PCB or Printed Circuit Board is to connect electronic components in a simple way, hold them, and reduce the complexity of a large electronic circuit.

Different Types of PCB

PCB or Printed Circuit Boards are classified into different types according to the substrate, number of layers, applications, tracks, frequency etc. So, the different types of PCB are,

Single-Sided or Single-layer PCB
Double-sided or Double Layer PCB
Multilayer PCB
Rigid PCB
Flexible PCB
Rigid-Flex PCB
High-Frequency PCB
Aluminium Backed PCB

Single Layer PCB

Single-layer PCB is the most usable and common type. It has a single conductive layer on the substrate. This type of PCB board holds the electronic components on one side only. As it has a single layer, it is best for small circuits. Of course, the design cost of the single-layer PCB is very low than other types.

Here, you can see the construction of a single-sided PCB below,

single sided or single layer pcb construction diagram

You can see here a single copper layer exists between the solder mask and the substrate.

Applications of Single-Layer PCB

Single-layer PCBs are mostly used for basic and low-density circuit designs.

Double Layer PCB

Double-layer PCB has two conductive copper layers. Here, the conductive layers exist on both sides of the board. Mainly two different technologies are used to place the electronic components in a double-layer PCB - 1. Surface Mount Technology(SMT) and 2. Pin Through Hole(PTH) technology.

SMT technology helps to hold and connect the SMD components on the surface of the board whereas PTH technology helps to hold the leaded components on the same side as the SMD components but connect to the opposite side conductive layer. I mean to say that, SMT and PTH, both components are placed on the same side of the board but they are connected on different sides.

Here, you can see the construction of a double-layer PCB.

double sided or double layer pcb construction diagram

Here, you can see two conductive layers exist on both sides of the substrate.

Double Layer PCB Advantage

The main advantage of the double-layer PCB is, large or complex circuits can be implemented with the double-layer PCBs.

Double Layer PCB Applications

Double-layer PCBs are used in mobile circuit boards, compact electronic power supply circuits, regulator circuits, etc.

Multilayer PCB

Multilayer PCB has more than two conductive layers. If the PCB has three conductive layers then also it will be called a multilayer PCB. All the conductive layers are laminated and insulated from each other. Generally, the multilayer PCBs are designed and manufactured in a Sandwich fashion.

Here, you can see the construction of a multilayer PCB.

You can see there are multiple conductive layers.

Application of Multilayer PCB

Multilayer PCBs are used for industrial electronic boards, medical boards, and other complex boards.

Rigid PCB Boards

According to the flexibility or folding feature, it is a type of PCB board. Rigid PCB boards cannot be twisted or folded. They are made up of hard substrate materials. Rigid PCB boards come in all types means - single-layer, double-layer or multilayer. Generally, there are four different layers that exist in a rigid PCB board such as - a substrate layer, a conductive copper layer, a solder mask layer, and a silkscreen layer.

Rigid PCB Applications

In most cases, rigid PCB boards are used such as computer boards, power supply boards, television boards, etc.

Flexible PCB Boards

Flexible PCB Boards are made up of flexible substrate materials such as polyamide, polyester film, etc. So, they can be twisted or folded without any damage to the circuit printed on the board. Flexible PCBs also come with a single layer, double layer or multilayer.

Flexible PCB Applications

Flexible Printed Circuit Boards are used in flexible solar panels, cameras, Organic Light Emitting Diode(OLED), robotics circuits, complex electronic circuits, etc.

Rigid-Flex PCB

Rigid-Flex PCB is the combination of Rigid PCB and Flexible PCB. It can be a part of a big circuit, where hardness and flexibility both are required. You may notice flexible printed circuit boards are mostly used to connect two or more rigid boards together. In these cases, flexible boards are carrying conductors only. On a mobile phone also, you can notice the camera is connected through a flexible board to the main rigid PCB board.

Rigid-Flex PCB Application

Rigid-Flex PCB boards are used in mobile phones, laptops, industrial boards, medical testing devices, etc.

High-Frequency PCB

High frequency in electrical and electronic circuits causes electromagnetic interference(EMI), unwanted signals, heat, etc. So, the PCB used for the high-frequency circuits are designed and manufactured in a different way. Generally, high-frequency PCBs are made up of FR4 grade glass materials, polyphenylene oxide(PPO) resin, etc. High-frequency PCBs are designed by considering important factors such as good mechanical strength, Dielectric Loss, Thermal Expansion, Water Absorption, etc.

Aluminium Backed PCB

In, normal PCBs fibreglass is generally used as a substrate material but in the aluminium-backed PCB, aluminium is used as a substrate. There are some important advantages for which, aluminium is used as a substrate such as aluminium has more durability than other materials, aluminium can dissipate heat very easily, it is recyclable. Aluminium Backed PCBs are used in some special applications and special electronic devices or circuits.

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