A Complete Guide to Understand Through-Hole PCB Assembly

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There are different strategies for mounting components on the PCB board. Once you mount the components, you will run tests to check whether everything about the PCB board is working perfectly. First, you need to learn about mounting components on the PCB board. You might have heard about the Through-hole PCB assembly process.

What is the Through-hole PCB assembly process?

To mount components on the PCB board, through the hole procedure, you will install components through leads. There will already be holes on the PCB, and you will use the lead to install those components through manual soldering or wave soldering. Through hole strategy is vastly used to manufacture single-layer PCB boards.

You will connect all the electronic components on the PCB board with the help of leads. After that, you make the connection stronger between them through soldering.

Types of Through-hole PCB assembly process

There are two types of Through-hole PCB types that you can consider according to the type of PCB board you are preparing:

Axial lead components

If you are going to use axial lead components to attach electronic components on the PCB, then this process consists of straight axial leads that would go through in a straight line with every end of the wire that would be attached to the components on the board.

Axial lead components examples

Following are a few examples of axial lead components:

  • Carbon film resistors
  • Resistors
  • Capacitors
  • Inductors
  • Diodes

Through-hole PCB assembly

Radial lead components

The second type of Through-hole PCB assembly is radial lead components. If you use this process, you will place radial leads parallel to the surface of the component. While placing radial leads along the components on the PCB, they will require less space because they get placed perpendicularly to the board.

Radial lead components examples

Following are a few examples of radial lead components

  • Photodiodes
  • RGB
  • LEDs
  • Ceramic capacitors
  • Photoresistors

Step-by-step guide of Through-hole PCB assembly process

Now we are going to discuss the Through-hole PCB assembly process in detail so you will be able to learn how this procedure works out:

Clean your PCB and components

Before starting your PCB, you first have to clean all the electronic components and the board with isopropyl alcohol. After cleaning now, dry the components and the board as well. Then you can start the process of installing components on the board.

Choose your method

You will require a plier to bend the leads so they will fit on the PCB, but you will bend the leads if you are using an axial component strategy. If you are going for a radial component, you can insert the lead through the holes directly of the PCB. You don’t need to bend them first.

Place the leads

The component should lie flat on the board, and once you bend the electric components on the board and insert them through the holes of the PCB, you need to cut the excess leads. It would help if you kept following the schematics and cutting off excessive leads.

Soldering process

Another important step of Through-hole PCB assembly is soldering. You can apply flux to both sides of the PCB, but you can only apply solder on one side. Applying flux to both sides of the PCB will help with heat conduction, and the soldering area will stay clean. You can apply solder to the underside of the board only.

Cleaning and inspection

Now it is time to clean the PCB and check every single electronic component to see whether everything is working perfectly or if there is any irregularity present in them. Every component has to be in its right place, and the soldering must shine.

Benefits of the Through-hole PCB assembly process

The following are the benefits of using the Through-hole PCB assembly process:

The reliability level is high

The reason for using Through-hole PCB assembly would be its high reliability and efficiency. Your PCB will have more resistance, which would be a more reliable option because the electronic components will stay in the right place.

The terminals will go through the holes on the board with soldering, strengthening the bond. The first benefit of using Through-hole PCB assembly is a high level of reliability.

Making adjustments is easy

If any component is not working properly, you will be able to adjust its position, or you can replace it without difficulty. While you are testing the PCB, sometimes, you find defective components, due to which your PCB needs to be fixed. You can change them right away. In the surface, mount PCB assembly process, changing components will be a tough task, but Through hole PCB assembly process, it will be easy.

Stronger bond between components

The bond between the electronic components on the PCB will be stronger if you use a Through-hole PCB assembly process. They will stay in their place easily. If you compare any other PCB assembly process with the Through-hole PCB assembly procedure, you will find that it is the best option if you want your component to share a strong bond.

More durability

Through-hole PCB assembly makes your PCB components more durable. They can resist shocks and won't move even an inch from their place. Any external factor won't easily affect the bond between the components. So, you can imagine your PCB's durability if you consider the Through-hole PCB assembly option.

Higher resistance

Most manufacturers use the Through-hole PCB assembly option when preparing the PCBs that would be required in harsh environments where there will be environmental hazards, shocks, and much more. The main benefit of using this strategy would be making your PCB more resistant to external factors. Any PCB manufactured through any other process won't last long in harsh and hazardous environments.

Robust solder joints

Sometimes the solder joints get rusty or loosen up, but if you are considering Through the hole PCB assembly procedure, the solder joints won't loosen up. They will stay the same for a long period. Your PCB will keep working, and the solder points won't cause any effect on its working.

Limitations of the Through-hole PCB assembly process

We have discussed the benefits of using the Through-hole PCB assembly process above. There are going to be a few drawbacks as well. So, you need to know them before making any decision. Following are the limitations you will face if you are considering the Through-hole PCB assembly option:

Not an ideal option for multi-layer PCB

You can opt for Through-hole PCB assembly if you manufacture a single-layer PCB. If you make a multi-layer PCB, then Through PCB assembly could be better. You will require more space to manufacture it, and the design will get quite complex.

Troubleshooting is also difficult because finding faulty components between the layers will take a lot of work. So, Through-hole PCB assembly is limited in that it works best for single-layer PCBs.

More surface space would be required as compared to SMT PCBs.

Doubtlessly you can use the Through-hole PCB assembly procedure to manufacture a top-class PCB because you have already read the benefits above. The bond between the electronic components will be stronger, and they won’t move from their place easily. The joints won’t loosen up, but you will require a lot of space to construct a PCB Through-hole PCB assembly process.

You will have to use a lead and get them through the holes to connect the electronic components from each other and to the board. To perform this process, you will require more space. A wide surface would be required for Through-hole PCB assembly compared to the SMT PCB process.

Uses of Through-hole PCBs

The following are the uses of Through-hole assembled PCBs:

Military and aerospace electronics

The military and aerospace environment will be harsh, but this doesn’t mean that they don’t require technology to survive there. All electronic devices consist of PCBs; without them, they won’t operate. An ordinary PCB won’t be able to survive in a harsh environment for a long time.

The electronic components might loosen up, or the environmental hazards might cause negative effects on the soldering. So, anything can happen if you don’t get a PCB manufactured through the Through-hole PCB assembly procedure.

Yes, Through-hole PCB assembly PCBs are mostly used in military and aerospace electronics because of the harsh and hazardous environment around them.

Is the Through-hole PCB assembly process an ideal option?

If you compare the benefits of Through-hole PCB assembly with the limitation, then through-hole PCB assembly is an ideal option if you manufacture a single-layer PCB. You can also use this procedure for multi-layer PCBs, but you should know that it would be a much more complex design.

You can consider Through-hole PCB assembly because you get more efficiency, and your PCB will have higher resistance and last long.

Final Words:

We have talked about Through hole PCB assemble quite in detail. Now you know the benefits and in why manufacturers use this way of installing components on the PCB. They are durable and they work best in harsh environment.


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