Why use a conformal coating?
Co-Authors and contributors
- Dr Lee Hitchens, Nexus
- Karl Hardcastle, SCH Technologies
There are several reasons for using a conformal coating or Parylene to protect a printed circuit board (PCB).
These reasons include:
High Insulation protection
Conformal coatings can provide a high degree of insulation protection for the circuit board during its lifetime when applied as a protective lacquer.
The circuit board normally starts with a high level of insulation when it is first manufacture as it is normally clean.
However, with time in the field and its natural environment the circuit can degrade in different ways.
The conformal coating can slow this degradation down.
High moisture and humidity protection
Circuit boards can be vulnerable to moisture and humidity whilst in the field of operation during its lifetime.
The conformal coatings are resistant to moisture and humidity and this can lead to a reduction in affects such as leakage currents, cross talk, electrochemical migration, dendrite growth and arcing across the circuit board.
Chemical and temperature resistance
The conformal coatings can be resistant to many types of solvents, chemical attack and be heat resistant.
Normally, a circuit board exposed to these types of environment would be degraded but the conformal coating can slow down the effects or even prevent them.
Ruggedisation
Conformal coating can prevent damage from rough handling, installation and reduction of mechanical and thermal stress.
Improve dielectric properties
Just as the conformal coating can protect the circuit from moisture it can also help to increase the dielectric strength between conductors .
This enables the design of the PCB to be more compact and small.
Barrier protection
A conformal coating can create a barrier against attack during the lifetime of the circuit board.
The coating material can prevent various types of particulate contamination reaching the surface of the circuit board, which can lead to problems such as corrosion.