There are four key reasons why Parylene masking and de-masking is more difficult compared to liquid conformal coatings.
Parylene is a vapour. When you are masking against a gas rather than a liquid then there is more of a challenge. So you need to provide a much better barrier with the masking process compared to the liquid coatings.
Parylene is immersion. Most liquid conformal coatings are sprayed and so the capillary is less compared to immersion in a limitless supply of material.
Stripping Parylene is hard. It is much harder to remove unwanted Parylene material on components that should not have been coated. Parylene is chemically inert (therefore harder to strip off or remove) and more difficult to see (no UV trace in most Parylene coatings). Mistakes can be more costly.
The Parylene can bond more to the masking materials. When the Parylene is deposited on the masking materials and circuit board it can bind the two together and it can take significant effort and care to remove the masking materials without damaging the board or the Parylene coating integrity.
The need to see the area being masked to ensure complete coverage and adhesion is paramount in ensuring that your conformal coating is masked correctly and does not creep under the masking tape. ET501G is not only the only commercially available ‘Silicone Free’ tape but is translucent allowing a clear view of what is masked and its full adhesion.
Elder supply ET501G as slit rolls or Dots and are able to convert to your required size’s in order to suit your every masking requirement.
TE Connectivity, a leading conformal coating masking boot manufacturer, can now boast that they provide the most complete range of standard and custom masking boots with the introduction of their new ESD range.
The ESD Safe Custom boots are constructed of static-safe masking materials and provide more options for engineers when selecting the right product for production.
This has given TE the ultimate range in masking boots and allows them to offer the best solutions to customers when considering conformal coating masking.
Nexus, the Conformal Coating Resource, have a section which has videos showing processes for conformal coating and also company video’s of which Nexus feels offer technical information to users of conformal coating.