What is Conformal Coating?
A conformal coating is a protective chemical coating that conforms to the circuit board. Its purpose is to protect electronic circuits from harsh environments that may contain moisture or chemical contaminants. By being electrically insulating, it maintains long-term surface insulation resistance level and thus ensures the operational integrity of the assembly. It also provides a barrier to air-borne contaminants from the operating environment, and avoids corrosion.
The advantages of conformal coatings are listed as follows:
Insulating properties allow a reduction in PCB conductor spacing of over 80%
Can help eliminate the need for complex, sophisticated enclosures
Completely protect the assembly against chemical and corrosive attack
Eliminate potential performance degradation due to environmental hazards
Minimize environmental stress on a PCB assembly
A separated operating room and air exhaust system are necessary for the conformal coating operation. For the better performance it better to clean the flux on the surface of PCBA. There are essentially four main ways of applying a conformal coating:
Brushing – It requires extremely proficient and skilled operators.
Dipping – limited to materials that do not cure quickly by moisture, oxidation or light. It is easy to apply the conformal coating since it needn’t any machine or tooling.
Selective robotic coating – All coating types can be used if the correct dispense head is selected. But this kind of selective robotic coating machine should be expensive so it may be suitable for mass production.
Spraying – All coatings can be applied in this way. It should be more wasteful than other options because the spraying coating cannot completely applied to the PCBA.