Last Updated on October 22, 2023 by Kevin Chen
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Other than functionality, the PCBA process should also focus on the protection of the printed circuit board. Components and the board itself should be protected from various forms of hazard. This is where conformal coating comes in. This is a special coating material that is applied on the printed circuit board with the core purpose of shielding the board and electronic components from various forms of hazards. In this article, we are going to discuss the main advantages of conformal coating for printed circuit board assembly.
Overview of conformal coating
As we have already defined, the primary role of conformal coating is to protect the printed circuit boards. These protective films are also used to act as an insulator on the printed circuit board. It insulates the board and its components not only from physical risks but also unseen hazards such as high temperatures and even unwanted electric currents or signals.
Conformal coatings usually exist in liquid form, however, there are some that re packaged and stored in aerosol forms. When applied on a printed circuit board, they form ultra-thin layers that will conform with the structural arrangement of the printed circuit board. This is where they derive the name conformal coating.
What are some of the materials that are used in conformal coatings? While there are many different types of conformal coatings, PCBA, and most electronic applications are quite sensitive when it comes to the selection of the materials to be used. The most ideal conformal coatings for PCBA include acrylic, epoxy, urethane, perylene, and silicone.
Each of the mentioned materials has unique physical and chemical properties. Some have higher temperature resistance than others. It is important to consider your application requirements before choosing the conformal coating type to use. For example, if the electronic device is likely exposed to chemicals and moisture, you will be safer with acrylic conformal coating. On the other hand, silicone-based conformal coatings are ideal for their high resistance to temperature.
Importance of conformal coating PCBA
Here are some of the top benefits of using conformal coating in PCBA:
Protection from electric interference
When it comes to PCBA, there are two main types of electric interference that manufacturers tend to focus on. These are electromagnetic interference (EMI) and radiofrequency interference (RFI). The use of conformal coating can help to provide adequate protection against these two types of interference.
These forms of electric interferences are generated as different electronic components on the printed circuit board operate. If unchecked, both EMI and RFI can affect the overall performance of the PCB module.
Electrostatic discharge (ESD) is another electric interference that needs to be avoided on the printed circuit board. It has the potential to cause serious damage to the electronic components on the PCB. A conductive coating is used to provide a shield against ESD.
The best conformal coating should be able to provide proper protection against these two forms of electric interference. Some PCB application areas such as aviation and telecommunication are sensitive and to EMI hence the need for proper protective mechanisms such as conformal coating.
Conformal coatings are also critical when it comes to the thermal management in the printed circuit board. The heat that is generated by different electronic components on the PCB is dissipated on the surface of the board. From there, it should be dissipated away. This is where the importance of conformal coating comes in. Heat-conductive coatings are good at dissipating this heat away from the board. Technically, conformal coating is considered part of heat management solutions in the PCBA process.
Protection from dust and water
The coating ensures that the tiniest components on the PCB are we-shielded from the effects of dust and dirt. In some applications, printed circuit boards are used in open spaces where they are exposed to environmental elements. Water is another element that has the potential to cause serious damage to the PCB. By using a conformal coating, you would have prevented such kinds of damage. It is easy for the PCB to perform to its optimum levels once you have eliminated all these environmental elements.
Save on the cost of PCBA maintenance
The use of conformal coating has a cost-saving implication. The protection that the coating provides means that you will not have to worry about the cost of repairing damaged PCB components.
How is the conformal coating applied during PCBA?
Now that you know the benefits of conformal coating for PCBA, we can assume that you are ready to apply the coating on the printed circuit board. There are four techniques for applying the coating on the printed circuit board. These are:
- This is the simplest method. It entails dipping a printed circuit board into a coating film. It is suitable for materials that take long to cure.
- Spraying: Here, an aerosol can or even a spray booth is used for applying the coating material on the surface of the printed circuit board. The spraying should be controlled.
- Brushing: Brushes are also used for coating the printed circuit boards. However, the technique requires high levels of skills and expertise.
- Selective robotic coating: Here, an automated selective spray is used for applying the coating on the printed circuit board during PCBA. This technique has a reputation for delivering high-quality jobs and also helps to eliminate possible errors that can arise during the coating process.
Now that you know the benefits of conformal coating, what next? It all depends on where you are on the spectrum of PCBA. If you are a PCBA manufacturer you will be in a perfect position to choose the best conformal coating that you should use on your printed circuit boards. On the other hand, if you intend to buy read-made PCBs, you should also inquire about the conformal coating that has been used.
As a buyer, it will be smart to use a PCB sourcing agent when it comes to confirming such technical parameters such as the coating that has been used. Using their knowledge and experience, they will be able to give you appropriate advice.
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