Liquid Conformal Coatings vs Parylene

Parylene is described as a conformal coating. Indeed, it is recognised and classed in standards as such.

However, Parylene differs significantly with the many different types of liquid conformal coatings.

The liquid conformal coatings include the acrylic, polyurethane, silicone and epoxy materials that are applied through alternative methods to the Parylene process that is chemical vapour deposition (CVD). These application methods include spraying, dipping and brushing.

Since the application methods are different for these coatings, and their material properties are different to the Parylene coatings, then it is logical that there will be significant differences in the performance of the coatings too.

How different can be seen in the key differences and tables below.

Key Performance Differences – Liquid Conformal Coatings versus Parylene

There are many differences in the coatings. However, there are several key differences between all of the liquid conformal coatings and the Parylene materials.

These include:

  • Application – The application methods are completely different. Chemical vapour deposition (CVD) for Parylene versus spray, dip or brush for liquid conformal coatings.
  • Conformal nature – The Parylene process produces a truly conformal coating thickness and can be almost completely uniform. The liquid process produces uneven coating thickness due to surface tensions during drying.
  • Pinhole free – Parylene is almost completely pinhole free if applied correctly. It is almost impossible to achieve this with liquid conformal coatings.
  • Barrier to moisture – Parylene is generally much less permeable than the liquid conformal coatings. It can waterproof a product at the right thickness.
  • Dielectric properties – Parylene is generally superior to the liquid conformal coatings. It achieves much better values in almost all cases.

Below are some more complete tables showing the different liquid conformal coatings versus the Parylene coatings.