Parylene is one of the most widely used and widely trusted conformal coatings in any industry. It is used in every application from space travel to microwaves, and it is strong, reliable, and long-lived--but before it can do any of that, parylene needs to have proper adhesion. Let our experts explain why a little cleaning goes a long way in this case.
Adhesion Mechanisms
The rule of thumb when it comes to parylene coating adhesion is that cleanliness is crucial. If the surface area is contaminated in any way, the adhesion may be interrupted, or the parylene may not be able to provide strong, long-lasting protection. This means that no matter the situation, properly cleaning the substrate material and using clean equipment is crucial. However, cleanliness is only the first step. There are a few additional mechanisms that are also important for strong coating adhesion (and they just so happen to rely on cleanliness).
Chemical bonds
Chemical bonding occurs at the place where conformal coating and the substrate surface meet. Strong bonding is necessary because it allows proper adhesion that will last for extended periods of time--but any contamination on the substrate surface can interrupt this bonding, so again, cleaning is a critical first step.
Adsorption
Adsorption takes place as the coating "spills" over the surface, which is what allows parylene to coat evenly the most unusual shapes and crevices. If contamination is present, the coating won't be able to flow freely and adsorption, as well as adhesion, will be interrupted.
Mechanical interlocking
When conformal coating dries and breaks through the substrate surface's top layer, mechanical interlocking is occurring. However, unclean surfaces are too smooth to allow mechanical interlocking, so a clean, rough surface is necessary.
Although all three of these mechanisms aren't required for adhesion, they help guarantee a reliable, long-lived bond between parylene and the substrate surface. This is why cleaning is a crucial part of the adhesion process.
Conformal Coating Cleaning Tips
What do you need to know about conformal coating cleaning? Let our experts provide some handy tips!
- The risks of skipping cleaning. Before you can decide how crucial cleaning is for your conformal coating job, you need to know the risks involved in not cleaning. Potential problems include adhesive failure which means you'll have to rework the entire project, which can be time-consuming, expensive, and frustrating.
- It's not always necessary. While cleaning is recommended, it's not always strictly necessary. It is possible to create an environment controlled enough to allow for successful adhesion without cleaning; it's crucial, however, that gloves be worn at all times, the surface never be touched, and that the surface itself is naturally clean and of good quality.
- Cleaning needs are unique. The thing about conformal coating is that it has applications just about everywhere, so there is no cut-and-dry handbook for every specific job. This means that cleaning needs are unique to the job, the goals, and more. It's best to contact conformal coating experts for help in deciding what's best for your job.
