Conformal Coating Guide
Here at the Newbury Electronics Group we offer fast-turnaround conformal coating solutions in the UK with the ability to order online via our sister company PCB Train.
What is Conformal Coating?
Conformal Coating is a thin protective film that is added to the surface of a PCB to shield the board and its components - thus acting as a barrier for the board.
Why is Conformal Coating Used?
Conformal coating can provide protection against:
- Environmental Conditions - dust, dirt and contaminants
- Heat - extreme temperatures
- Moisture - humidity and condensation
- Chemical Corrosion - solvents and acids
- Mechanical Stress - impacts and vibrations
Conformal coating is most commonly utilised within aerospace, automotive, healthcare and military applications.
As technology develops and hardware becomes even more robust the use of conformal coating in modern electronics is becoming more common with longer lifespans and better performance expected across industries.
Do I Need Conformal Coating?
Although all PCB designs are different, the simple answer to this question is “yes”. Opting for this feature can ensure that the solder joints, exposed traces and electronic components that make up your PCB remain protected from damage and corrosion when put to use in any environment. The addition of a protective coating can also increase the lifespan of your PCB, guaranteeing reliability and high performance at every turn.
What types of conformal coating are there?
Various types of conformal coating are available, each designed to provide a specific level of protection. The different types of Conformal Coating include:
- Acrylic Coating
One of the most popular conformal coating solutions is the acrylic coating. Acrylic conformal coating, is what our experts use here at Newbury Electronics, it is notable for its high dielectric strength. It offers excellent protection against humidity and salt mist, whilst possessing superior adhesive capabilities. A further advantage is that it can be easily removed, which makes rework and repair very simple. Widely regarded as one of the most cost-effective solutions utilised in consumer electronics and general PCB manufacturing.
- Silicone Coatings
Providing durability, flexibility and resistance to environmental damage, silicone conformal coating is often the choice for applications which may be exposed to harsh chemicals, solvents and acids. It is highly flexible and able to expand and contract without cracking, making it useful for surfaces that are subject to movement.
- Polyurethane Coatings
Providing extreme toughness and resistance to abrasion, Polyurethane conformal coating widely used in construction industries due to its durability, chemical and weather resistance, flexibility and other crucial properties.
How Is Conformal Coating Applied?
The different forms of conformal coating can be applied in several ways. This method of application is usually dependent on the requirements of the board and the client, as well as the equipment a PCB manufacturer has at their disposal.
For low-volume applications, many choose to brush the coating onto the PCB manually. Such a technique requires a practiced hand, and may be the way to go for rework or repair. Elsewhere, it’s not uncommon for PCB manufacturers to use handheld aerosol cans or spray guns to apply the conformal coating. Again, as this is a delicate process, it should only be attempted by someone with sufficient knowledge and experience of spraying techniques.
Larger companies, such as the Newbury Electronics/PCB Train, rely on specialist machinery to automate the conformal coating process. This involves programming a system to complete a set of spray application tasks by a 6 axis CNC controlled fine jet spray unit followed by conveyorised baking and curing.
Alternative methods include a dipping process in which the circuit board is immersed in the coating solution. The latter requires the PCB to undergo masking beforehand and is largely superseded by automated CNC conformal coat spray systems. All of these methods of application need to be carried out under the watchful eye of industry experts, who will be required to follow strict quality control processes.
Are There Any PCB Coating Standards?
There are a number of standards relating to conformal coating, but Newbury Electronics/PCB Train work with IPC-A-610 section 10.8.