How To Assemble A PCB Board? Step By Step Guide 2022

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Printed Circuit Board Assembly (PCBA) is a rapidly evolving industry in which the invention of the PCB and the commercialization of the PCB played a decisive role. Electronic assembly based on PCB called PCBA.

In order to give an overview of the development history of the electronic assembly industry in the world, thereby envisioning the path to form the name PCBA, we would like to introduce the development processes that the electronic assembly industry has undergone.

What is assembly of PCB Board?

The assembly of printed circuit boards is composed of tasks that involve multiple teams and even different companies, in the case of assembly outsourcing. For this reason, it is important that everything is done following well-defined processes, in a clear way and, preferably, with the support of all involved parties and a production schedule.

The biggest difficulty encountered is that the development of electronics projects starts with a determined team that, little by little, starts to incorporate new people and possible partners in the execution.

 In small companies, and even in large ones, not aligning communication between everyone involved results in communication difficulties and adjustments that could be avoided with prior planning.

Concept behind PCBA

Ideally, even before the first step, all those responsible for each of the steps are elected and participate by giving their opinion from the product's conception, including the assembly partner. Of course, it's impossible to predict certain changes along the way, but even they are easier to get past when the initial planning is clear to everyone.

The rework is one of the greatest enemies of the production of electronic boards. A good product is almost always developed by multiple teams. Each of them, in their expertise, knows what is best for the performance of the final result.

The product design team, for example, at first has nothing to do with executing board assembly. However, if both are together since the beginning of the project, they can think of better solutions to combine functionality and beauty without harming the equipment's operation.

Next, we separate, step by step, some details that must be observed when making the printed circuit boards viable.

PCB assembly is the process of installing various components onto a printed circuit board.


Assembly involves assembling the components. Installation, in turn, is of three types:

  • SMT (surface mount technology) - surface mount
  • THT (Through hole technology), output mounting
  • THT + SMT - lead + surface mount (mixed)

With surface mounting, electronic components are attached directly to the board on both one and two sides. Using soldering, the pins of the components are soldered to the board tracks, and they do not go through the board. As a result, it turns out to maximize the working area where the electronic components will be attached.

For lead-out mounting, the components are fixed in plated holes on the board. The contacts are soldered to these holes and securely fastened. The main feature is that THT components pass through the board. Solder bumps form on the back of the board.

THT mounting has certain disadvantages:

  • THT components are usually large and heavy
  • The board requires preliminary preparation (metallization of the holes for soldering)

Despite the disadvantages, THT components and, accordingly, THT mounting are often indispensable.

Storage and Handling of PCB Components

Components in good condition are an essential part of the assembly of printed circuit boards. Most components have special storage requirements regarding humidity and temperature that must be strictly adhered to.

 They are described on the packaging of each product, but they are not always taken into account when the company is not experienced in this type of assembly.

Solder paste

The application of solder paste is one of the most important stages of assembling electronic boards, and also one of the largest sources of error.

 In addition to having good equipment to carry out the task, it is essential that some care taken with the folder itself is taken into account, such as: stencil in good condition, equipment support, quality of the folder, cleaning, among others.

Insertion of components

It must be highly accurate, especially on boards with very small or critical components like BGAs where the distance between the balls requires perfect component centering. Today it is already possible to assemble smaller and smaller equipment with multiple functions. However, this reduced size requires even more added care and technology.


Each plate requires an ideal reflow temperature and this can only be measured at the sacrifice of a pilot plate. Only then is it possible to know the ideal temperature for perfect remelting, with quality soldering, but without damaging the plate. Both too much and too little heat often causes irreparable damage to the final result.

As the structure of components became more complex, their assembly technology also demanded changes that provided additional utilities and functionality. That's how PTH and SMD came about.

These are the most common ways to assemble electronic board components. And for you to understand how they work and when to choose one or the other, we have prepared an article explaining everything about these two types of encapsulation. Follow up!


As we have seen, the assembly of an electronic board is generally categorized into two types. The oldest is the PTH mount, or Pin Througt Hole, something like “terminal inserted into hole”. This assembly involves drilling very small holes in the board where the component terminals are inserted and then soldered.

Currently, PTH assembly is considered a bit old-fashioned, but it remains widely used, especially in applications where budget is a crucial factor.


The second category of mounting an electronic board is known as SMD, Surface Mounted Device. The SMD does not require drilling the electronics board, because in that case the components are assembled using more advanced tools and equipment.

In SMD, components are soldered to the board surface, without the need for holes. This is a more robust way of mounting an electronic board compared to PTH because there are no holes to form weak spots in the board.

Difference between SMD and PTH assembly in circuits

SMD technology is newer, but this can lead to the misinterpretation that it is preferable to Pin Through Hole technology. You need to look deeper into the issue before making a decision.

SMD mounting plates

The SMDs components emerged for an economic necessity. As they have terminals in their package, less time and material is used. In addition, this technology allows you to create smaller components, which ends up making the price more attractive.

SMD devices are mostly found on boards where device size is a major concern. They can also be used on boards or devices that contain both PTH and SMD components, as some types, such as transformers and heat sinks, are not suitable for surface mounting.

The choice between one and the other, therefore, will depend on the needs of the printed board. The PTH components are easier to weld, but when required a higher level of complexity, you need to opt for SMD.

Main differences

To better understand, there are some points that differentiate one technology from another, which are summarized below:

  • As SMDs components are smaller, they take up less space compared to PTH;
  • Components in SMD have the pads in their body, and can be mounted directly on the board surface;
  • The density of components per area in SMD technology is higher than in PTH;
  • In SMD, the components per area in SMD technology is greater than in PTH;
  • SMD technology is used when large production is required, which leads to low cost of unit sets;
  • Manual welding in SMD is very complicated, so it is necessary to invest in automatic welding machines;
  • The design, production, features and technologies are more advanced at SMD;
  • PTH technology is primarily used in prototyping.

Whichever function you outsource, one thing is a fact: you optimize your time, as you can invest in other areas of your business. With outsourcing the assembly of electronic boards it is the same thing!

Advantages of Hiring Professional PCB Assembly Company

There are many other advantages to hiring a company to assemble electronic boards. Check out some:

Very high quality

By relying on specialized professionals for the assembly of printed circuit boards boards, you guarantee that all processes will have quality assurance. High-tech equipment and qualified staff make the difference to offer your customer the best!

Easy access to components

Obtaining domestic or imported components can be a difficult task, but specialized companies have greater access. In addition to advantages in negotiations!

Cost reduction

In addition to the complexity, the assembly of PCB boards requires a high cost. It is an investment that might otherwise be applied to your business when you outsource a company for the job.

 Who should carry project of pcb assembly?

It must be carried out by a specialized team and take into account specific factors related to the assembly, such as the size of the margin or the proximity of the components, for example. At this point, it is clear why involve the automaker from the beginning.

A good project also takes into account external factors, such as:

  • Costs
  •  Market
  •  quality of the chosen pieces, among others

 At this stage, interdisciplinary work is also essential. A project team well aligned with the material purchasing team will certainly think of a cost-effective solution that is much more interesting for the company and competitive for the consumer.  


Always Purchase PCB Board Assembly Components from Reliable Company

Companies that choose to internalize material purchasing processes for the assembly of electronic boards may have problems. Due to the great specificity, if the team is not used or trained, it is common to export the wrong components (the names are similar and sometimes a letter changes everything).

Ideally, everything is checked and validated with the other teams. Aspects such as obsolescence must be checked and, in cases of choosing products very close to the final date of manufacture, they must be replaced by others. This replacement must be supported by the technical team, never directly by the purchasing team.

PCB Assembly follow-up

Monitoring the assembly is a fundamental step in making the printed circuit board. It is important to observe if the company has the adequate technical capacity and fulfills the prerequisites for obtaining the best possible result.

In this case, it is interesting to carry out technical visits and observe the reputation of the assembler; this will be a differential in the final result.

PCB Assembly Functional Tests

The manufacture of printed circuit boards ends with the testing phase. They must be made on a sample of products or, if it is a small batch, on all of them. If possible, the ideal is to test them on the product as soon as possible. That's because it can suffer interference that can only be perceived with all the parts fitted and the product assembled.


We carry out the entire process of purchasing materials, choosing according to urgency for purchases from reliable suppliers. Every purchase is made transparently with the customer, with only the process management being charged. We can do the import process or supplier specification.


KINGFORD has highly qualified personnel and automated equipment for assembling electronic components in the areas of SMT (surface mounting devices) and THT (through hole technology). Our machines are able to assemble and weld the most complex components, thus guaranteeing excellence and quality in the manufactured products.


With an experienced electronic engineering team we are able to develop test jigs for industrialized boards. Our personnel can make firmware recording or necessary adjustments for product testing. We assist the customer in the entire product certification process with the competent bodies, adapting the project if necessary.


It consists of the integration of electronic boards to their cabinets, through electronic component kits (SKD), software integration to the products, final finishing with labeling. We have our comprehensive assemblies area for the systemic manufacture of any type of equipment, from product assembly to packaging.


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