All You Need to Know About SMT PCB Assembly

Views: 345 Author: Site Editor Publish Time: Origin: Site

SMT or surface mount technology is also known as planar mounting. Due to the advancement in technology and electronic devices, the conventional assembly in which the components were inserted through holes was considered old and inefficient. In SMT assembly, the components are placed on the PCB with zero errors and are regarded as accurate and efficient.

Technology is getting more complex daily, and all the technology used in electronic devices nowadays relies on SMT assembly.

SMT assembly could be better itself. It also has flaws, but for the time it is the best for the technology used nowadays. SMT has both its pros and cons. In one place, it is cheap; on the contrary, it has compatibility issues, and you have to look for alternatives.

All the information you need to know about SMT PCB assembly

In the late 1970s, the conventional through-hole method was replaced with Surface mounting because the through-hole method was inefficient and inaccurate. Since the replacement surface mounting is still used. The technology used in smartphones and cars all uses surface mounting technology.

Nowadays, everything is run on computers and laptops, and the assembly of the motherboard of computers and laptops is completely based on SMT assembly.

Change in the conventional method

In the 1960s, when it was introduced, it did not bloom and was not used in devices until the 1980s when 10% of electronic devices started to use this technology, and since then, it has seen a rise and not a decline, and till this day surface mounting technology.

 Before this, the conventional through-hole method was used to place the components on the board, specifically through a hole cut in the PCB board. The placement of components on the board using the through-hole method was hard and required too much attention. With SMT assembly, you don't need any holes or leads to place the components on the board; you only need a solder.

Huge impact on the size

Due to the introduction of SMT, electronic devices became more portable and smaller. With the through-hole method, you needed a large size and then cut a hole in the board to place the components. Due to this, the size of the component used to be large as well. With SMT, there was a great reduction in size, making electronic devices faster and smaller.

Present mounting technology

Almost all of the electronic industry uses surface mounting technology for electronic assembly. All smartphones, PC components, and cars use this mounting technology to place the components on the PCB board.

The technology in electronic devices has changed a lot in a few years, but SMT PCB assembly is still used in all electronic devices. There have also been changes in the SMT so that it will co-exist with the latest technology.

Easy mounting technology

The through-hole method was complex and required great attention when mounting components to the PCB. Holes were required to be made on the board, and then placing the components on the board was also very difficult. Since the introduction of SMT PCB assembly, it has made the placement of the component to the PCB very easy.

 There is no rocket science in the mounting process in SMT; the component or surface mount devices are picked and then mounted directly on the board with the help of a machine. During this, thousands of components are connected to the contact pads with the help of solder.

Preparing the PCB and Initial Circuit Board Design


The rise in nanotechnology will be a challenge for SMT. The circuitry will require a change in the future. With nanotechnology, the devices will be much smaller and faster. Replace SMT with nanotechnology it will need many years, but eventually, SMT will be replaced with nanotech due to the advancement in technology every day.

Benefits to the PCB assembly

The main focus of SMT is to minimize as many problems as possible in the PCB assembly. SMT has achieved what the through-hole method couldn't.


SMT brings reliability to the PCB mounting due to the less likely to be affected by vibrations and shock. In the through-hole method, there was always a chance of component failure due to soldering, while in SMT, this problem is completely minimized.

Eases the process

SMT assembly on the PCB is much easier and simple than through-hole technology. In through-hole technology, the leads of the component had to be bent into a shape so that it goes through the holes in the PCB board.

Relaxation in components

In SMT, you can use much better components which is different from though-hole technology. In through-hole technology, you had to use special components which were the best for the hole in the PCB. SMT allows you to use excellent components, with the help of which you can reduce the size and better performance.

It can be used in many industries.

With the introduction of SMT, it had many applications, not only just in consumer electronic devices but in telecommunications, medical devices, and industrial control systems.

Procedure of SMT you need to know about

SMT assembly is impossible without a solder. The SMT assembly consists of 5 primary steps: -

Solder paste printing

This is the first step, and the solder paste is placed on the PCB pad through openings. This placement is done with the help of a solder paste printer.

Mounting of chip

With the help of a chip mounter, the components are mounted to the exact position on PCB. The components should be placed on the PCB designed for them, or else the component and device won't function.

Reflow soldering

In this step, the solder paste is melted, which makes the components stuck to the PCB. After some time, when the paste is cooled down, the reflow soldering is done with the help of a reflow soldering oven.

Clean up process

A clean-up process is done via a cleaning machine. Cleaning is important to remove all the hazardous residue left from reflow soldering. If the residue is not cleared on time, it can cause serious functioning problems later.


After cleaning, an assessment is carried out to check the compatibility of the assembly and whether the components are placed in their exact location. Different equipment is used to carry out the assessment or inspection.

Advantages and disadvantages of SMT PCB Assembly to know about

The SMT PCB assembly has advantages and disadvantages, but it has given off advantages more than disadvantages.


Best for small components

SMT PCB assembly is the best for smaller components. Due to SMT, electronic devices have become portable and faster.


SMT PCB assembly is cheaper and much more affordable than through-hole technology. You don't need to drill holes into the PCB. SMT can also produce high volumes.


  • Compared to the older technology, SMT is far ahead and faster. Due to smaller components, SMT has become faster and more efficient than through-hole technology.
  • Less likely to make an error

Due to its simple mounting process, the window of errors occurring is very narrow. In SMT, the components are picked and placed on the PCB with the help of a machine, and the error percentage is very less. Even if any small error occurs, it can be easily fixed with the help of a solder.


In SMT PCB assembly, the components can be placed on both sides of the board. This way, you can place many components in a small place.



SMT components are incompatible with the sockets on the board, making you turn to alternatives and older technology.

Requires too much attention

For the component to be attached to the PCB board requires great attention; any flaw in the placement can fail. The design and the placement should be perfected; even though it is automated by machine, it still needs attention.

Expensive repair

It won't be easy to repair if any repair is required, and even if you can repair it, it will require expensive tools and professional operators.

What is the role of Conditions For SMT PCB assembly?

Environmental, mechanical, and temperature stress can directly affect the SMT PCB assembly. This can be minimized by using both SMT and through-hole technology. The increase in the temperature can directly affect the SMT assembly as the paste will start to melt with the intense temperature.

Uses of SMT PCB Assembly to know about

The most important use of SMT is the creation of portable and faster electronic devices. If the SMT was not introduced, the devices we would have had would always be huge and slower.

Electronic devices

The main industry in which SMT is used is the electronic device industry.

Medical devices

SMT PCB assembly is highly used in medical devices and equipment.


SMT PCB assembly is also used in telecommunication devices.

Other use

Another use of SMT PCB assembly is in industrial control systems.


The SMT PCB has brought a huge revolution in the electronic device industry. Comparing SMT to through-hole technology, SMT is far better and more efficient than through-hole technology. The revolution caused by SMT has made electronic devices more portable and faster. With the technology changing, SMT will only survive for a short time. Nanotechnology will soon replace SMT, as nanotechnology is the future.


Contact Us



Company Name