The majority of conformal coatings used in the world to protect electronic circuit boards are made from organic based resins.
These organic conformal coatings can be further subdivided into resin types such as
- Acrylic
- Polyurethane
- Epoxy
- Acrylic urethane blends
Although the majority of conformal coatings being used in this group are acrylic materials there is a considerable amount of coatings made from polyurethane.
Solvent based acrylic conformal coatings have been historically the number one choice for moisture protection of printed circuit boards and they provide excellent humidity resistance.
They also dry quicker than nearly all the other conformal coating types, they are easy to use in production and are easily repaired.
However, acrylic conformal coatings have very little chemical resistance. So, they are poor at protecting circuit boards in harsh chemical environments.
This is where polyurethane conformal coatings are considered.
Using polyurethane conformal coatings to protect against chemical attack
Polyurethane (UR) coatings also provide good humidity & moisture protection compared to acrylic materials.
But, what is key to their selection as a protective conformal coating is that they also offer excellent chemical resistance to the circuit board.
The reason for this is that UR coatings cure rather than dry. That is they cross-link once applied to the circuit board by one of the many methods including solvent evaporation (initial stages), heat, UV, moisture and catalysed cure.
This cross-linking of the polymer chain provides the chemical resistance for which the UR coatings are generally selected.
This makes them excellent conformal coatings where the chemical attack is a potential hazard for the electronic circuit boards. This includes sectors such as aerospace, military and industrial sectors plus other diverse areas such as medical and commercial electronics.
Need to find out more?
Find out more about using polyurethane conformal coatings to protect printed circuit boards in a chemical environment here or contact us directly and we can help you.
If you are new to Nexus and our work on conformal coatings then a good place to go is our Start Here page or our free conformal coating eBook.
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