Definition

Author

  • Dr Lee Hitchens, Nexus

Contamination is debris found under, trapped in or on top of the conformal coating on the circuit board.

This contamination may be detrimental to the long-term reliability of the circuit.

Download our PDF guide Solving conformal coating problems in the application process now.


Examples of conformal coating contamination

Examples are shown in the images below.


Causes of contamination

Contamination can come from a variety of areas.

This includes:

  • The pre-production stages of laminate and component manufacture
  • The process stages during application
  • The drying / curing stages

How to prevent contamination problems in conformal coating

  • Improve Cleanliness: Before production starts, all parts of the circuit should be fit for purpose in terms of cleanliness.
  • Clean the Process: Once ready for assembly, the board production process should not add unwanted contamination to a circuit board.
  • If a cleaning process is to be used before conformal coating then this will clean the circuit board to an acceptable level.
  • Clean the Coating Process: The conformal coating application process should not add contamination. This includes all the stages after cleaning including masking.

The areas should be contamination free to a level that does not produce significant defects.

Generally, conformal coatings are not produced under clean room conditions.

However, adopting many of the processes that the clean room does can aid this reduction.

Download our PDF guide Solving conformal coating problems in the application process now.


 Links

BlisteringBlushingBubbleContamination
Capillary FlowCorrosionCrackingDelamination
De-wettingDiscolourationFish EyesLayering
MealingOrange PeelShadowingUneven coating