Technology, Process, Techniques, and Tips for PCB Assembly

Printed circuit board assembly is known as the process of assembly or soldering electronic components to a printed circuit board (PCB).

PCB assembly is known as a very challenging aspect when it comes to electronics manufacturing. You just have to do it properly whether in digital watches, industrial machines, etc. Glad you are here because this guide explains everything related to pcb assembly. Please keep reading

What is PCB Assembly?

Before assembling the electronic components of a circuit board, it is simply referred to as PCB Assembly, Printed circuit board assembly or printed circuit assembly. To ensure the success of this process, there are different automatic and manual tools for PCB assembly used.

Please note that assembling the printed circuit board is much different from the PCB manufacturing process. When we talk of PCB manufacturing, we deal with several processes, which include the creation of the PCB prototype and PCB designing.

As soon as the printed circuit board (PCB) is set, now comes the need to solder passive and active electronic components to it before it is useful in any electronic gadget or equipment. Assembling the PCB components has to do with the:

  • Circuit board purpose
  • Printed circuit board type
  • Electronic components types

Things Necessary for Printed Circuit Board Assembly

Below are the consumables, electronics parts, and tools necessary for PCB assembly:

  • Electronic components (the basic ones)
  • Printed circuit board
  • Soldering materials, which includes solder bar, solder paste, solder wire, BGA solder balls, solder preforms (this depends on the soldering type you wish to perform)
  • The soldering equipment, which includes wave soldering machine, soldering station, testing and inspection equipment, SMT equipment, and more
  • Soldering flux

Once you have all the equipment mentioned above, the raw materials and electronic parts are arranged, then you are set to begin the process of printed circuit board assembly.

PCB Assembly Techniques

At this stage, there are two main PCB assembly techniques that are available to be used by the PCB designer. These methods include

  • Manual PCB Assembly
  • Automatic PCB Assembly
  • Mixed Technology or Mixed Assembly

Note that the PCB assembly technique you should use depends on the different variables. Also, they can be changed easily, depending on the necessary steps for the assembly. Have you been wondering what technique is the best for you? Then you shouldn’t worry anymore.

This is a very big decision for you to make. This is why we have done some work and generated some questions to assist you.

  • What technology will you make use of?
  • Will you use the through hole (thru hole), surface mount technology, or mixed assembly?
  • Are there components requiring soldering at different points rather than the remaining elements?

To help you understand and choose the most appropriate technique, let’s go ahead and discuss them.

Manual PCB Assembly

This pcb assembling method is to be used with the through hole parts that need to be placed manually onto the board. However, with the thru hole parts, it is advisable to make use of wave soldering.

Take note that during the through hole assembly process, there is a need to place the electronics and components onto the PCB. Once done, you sill solder the leads making use of wave soldering. Typically, there has to be an individual to help in inserting a component in the marked PTH.

Immediately it is completed, go ahead and transfer your PCB into the next station whereby the next available person will be ready and given the assignment of fixing a second part.

The cycle of the task keeps going on until the final part is ready and the PCB assembly becomes set. This is a very suitable method of you aim to produce just a few printed circuit boards (PCBs). Besides it relies greatly on human input, most especially when placing the components.

This means that the designer can pick and also place the electronics using tweezers. Once again, it is a purely visual inspection procedure. Designer inspector inspects the board to help in identifying possible faults. This is after the reflow soldering.

Manual pcb assembly is very good when working with a specific budget due to the fact that it doesn’t require buying expensive machines.

However, there are downfalls for this method, which is mainly inaccurate. Due to the fact that humans are not perfect, few batches of printed circuit boards can be completed, as well as inconsistencies present in the output.

Automatic PCB Assembly

This technique generally utilizes the state-of-the-art machines that are totally automatic. For instance, surface mount components are usually worth positioning using the automatic pick and place machine. Once again the reflow soldering is usually used for the surface mount components. This is also performed in the reflow oven.

 Also, the automatic solder stencil is useful for the application of the solder paste into the printed circuit board (PCB). Lastly, inspection machines of high tech are useful in confirming and checking on the printed circuit board assembly’s quality. Some include: X-ray inspection machines, automatic optical inspection machine.

To crown it up, this is possible as a result of soldering control, absence of versatile machines and human input, and precise monitoring. With the automatic technique, you are sure of output consistencies, utmost efficiency, as well as limiting defects.

Printed Circuit Board Assembly Using the Through Hole Components

smt manufacturing

The electronic components having leads that come out and are also inserted via tiny holes present in the printed circuit board for soldering can be referred to as the thru hole electronic components.

Furthermore, the soldering or assembly proves for the components in clued hand soldering and wave soldering. Wave soldering is the PCB assembly process whereby solder having the solder bar form are placed in a high temperature bath. The solder stays in that bath in the molten form and then creates a wave at a very high temperature.

 This temperature range has to do with the solder type. Traditional tin or lead solder has a lower melting point compared to the lead free solder type. Also, the PCB and the entire thru hole electronic components present in the holes is then passed over the molted solder using the conveyor belt.

The entire wave soldering type of the PCB assembly process involves these steps

  • Insertion of the electronic components
  • Applications of flux
  • Preheating
  • Wave soldering
  • Cleaning
  • Testing (functional test)

On completion of wave soldering, the printed circuit board assembly is then cleaned and also tested (functional test). One a defect of the solder joint or fault is detected, then it will be sent to rework. This is usually done by hand.

Hand soldering or manual soldering is usually done in the manufacturing using with reduced work load as well as in repair/rework jobs. A very reliable soldering station or flux and solder wire and soldering wire are utilized in the whole manual soldering process.

Surface Mount Technology Process for PCB Assembly

SMT assembly, which in full is surface mount technology, is a process of PCB assembly, which is great for the SMD components. Furthermore, these SMD components do not have legs or leads. Also, they are mounted onto the surfaces of circuit boards.

The electronic components, equipment, as well as other soldering metal that is used during the smt assembly process isn’t the same as that is used in the through hole soldering process. Let us consider the steps involved using smt assembly.

Printing of the solder paste

Apply your solder paste in a uniform manner onto the printed circuit board through the print of the solder paste. If you wish to make sure that your solder printing is perfect and accurate on the circuit board where you will be mounting your components, you can make use of a template. This sheet is referred to as the solder screen or stencil.

Because many manufacturers usually work with high quality products, then they must inspect and check their products immediately after the printing of the solder paste.

Mounting of the components

Immediately you finish the solder paste printing, then the PCB is automatically sent to the pick and place machine. In this machine the components, as well as the integrated circuits are usually mounted on the pads with the solder paste effect.

Next, is the expert installation of the components onto the PCB board making use of the component reels present in the machine. The component reels also play a very significant role in the process. What they do is that they rotate in order to supply the different parts onto the machines that will attach pieces onto the circuit board.

Reflow Soldering

Once the parts are mounted onto the board, go ahead and ass the printed circuit board onto a furnace that is set to a temperature of about 223 degrees Centigrade. This high heat leads to the melting and liquefying of the solder paste.

After the application of severe heat, you then cool down the board. This makes the firm solidification of the solder binding all the SMD components onto the circuit board.

Hiring a Professing PCB Assembly Service

Now, you know everything regarding PCB assembly process and for sure, there are some questions on your mind. The most frequently asked question is how do I hire an expert PCB assembly company or where can I order pcb assembly service online? It is exciting that we have reliable information, which will assist you in that regard. So continue reading.

First, this issue is a sensitive one, which you must get right. Trust you wish to work with a company that will handle the assembly in line with your specifications. This should be the main objective of any company offering PCB assembly services.

The company must make you aware of all the details of your design type. For this reason, here are some steps. Check them out.

Work with a reasonable and feasible timeframe

Rushing to work with just any company could lead to losses more than you ever imagined. This leads to wastage of more time. This is why it is very important that you have a good understanding of PCB assembly services the company offers before you go ahead to sign a deal with them.

Also, make important and detailed inquiries with respect to the company. Once there is a delay in response, just move onto the next company.

Consider the Experience of the Company in the Field

Note that exposure is essential. It is necessary to collaborate with a company having the necessary experience to match your job requirements and needs. In order to get this information, check on the website of that company.

Know how long the company has been functioning, the batch sizes they prefer, types of after-sale services offered.

Access the Quality

Before choosing any company, it is advisable that you search for one that delivers high-quality job. This evaluation is necessary before you start the project. You can order something small from the company just to see it their quality matches and meets your expectations.

Make Inquiry regarding the Inspection and Testing Options

In order to access and check the achievement and quality of the objectives, the right testing options and inspection are very necessary. Also, if you fail to conduct inspections or comprehensive tests can lead to huge losses for clients. Some tests to be conducted include automatic optical inspection, verification of the internal circuit, checking the component level, etc.

Check out for the customer support services

Customer care is a small issue but an important one, which many usually forget. A support system’s seriousness level will let you know the type of company that you are forming a partnership with. Customer support is always present in outstanding companies. Also, this shows that they are set to solve the issues of customers

Draw comparison of costs

Note that finance is important. Sure you want to receive the best value for money and at a very affordable price, while delivering high-quality products to customers.

Warning signs

Check out the following warning signs. If you notice any of these, just find another company

  • When there is poor communication and unresponsiveness
  • The company is inflexible and rigid to seek solutions relating to your project
  • High pricing
  • Longer time to complete the project


This is everything you should know about PCB assembly. With this, you can handle PCB assembly all by yourself. Work with this guide all the time.

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