Conformal coating is a protective non-conductive chemical coating which can be applied to circuit boards. Its purpose is to protect the electronic circuits from damage due to contamination, salt spray, moisture, fungus, dust and corrosion caused by harsh or extreme environments.
By applying conformal coating, and electrically insulating your boards, it maintains long term surface insulation resistance (SIR) and ensures the integrity of your assemblies. Providing a barrier against contaminants and preventing corrosion. Coatings also help prevent damage from rough handling, installation, and reduction of mechanical and thermal stresses. It can also prolong the life of the product during its operation.
How does conformal coating work?
A protective barrier is applied to sensitive electronic components offering additional protection against the harsh environmental conditions that your product may face, such as moisture, chemicals, debris and vibration. They are not designed to be a total board sealant but offer a breathable protective layer.
Conformal coatings are typically used in defence, automotive and aerospace industries, where protection from moisture, aggressive chemicals and vapour, salt spray and mechanical vibration is critical. Conformal coating not only offers your product protection, but also enhances your products reliability, thus reducing potential future costs and failures.
Benefits of conformal coating:
Insulation, allowing reduction in conductor spacing
Reduce the need for complex, sophisticated enclosures
Minimal effect on component weight
Protection against chemical and corrosive attack
Improve performance and reliability of products subject to environmental conditions
Provide mechanical support and vibration resistance
Enhanced product reliability
Applying a conformal coating
Essentially there are 3 main ways to apply a conformal coating to protect your boards.
Usually the highest volume technique. Boards are dipped in the conformal coating and coating penetrates everywhere. Masking in this application must be perfect to prevent leaking. Due to design, many PCB boards are unsuitable for this method, but if designed with conformal coating in mind then the ‘dipping’ process can be used in high volume manufacturing.
Suitable for low volume manufacture, finishing and repairing units. Requires highly skilled operatives to get a suitable protection level.
Coatings are applied with a spray aerosol or dedicated spray booth using a spry gun and is the most suitable method for low to medium volume manufacture. Most coatings can be applied this way.
After boards are conformal coated they will then need curing either by air dry, oven dry or UV light cure. Once the process of coating has been completed the coating is clearly visible as a clear and shiny material, some are hard while others have a slightly rubbery texture.
The team at 4e have been applying conformal coatings for nearly 20 years in military, medical and aerospace products. Meanwhile, Stock Electronics, which has produced motor control products for outdoor and harsh environments for 30 years, continues to use a range of conformal coatings across its product portfolio.