Parylene conformal coating is a very robust coating, but sometimes it is not the right fit for a customer’s application for one reason or another. The entire conformal coating process is based on first identifying the standards to be used and customer’s protection desired. It would therefore only make sense that there are alternatives to parylene for different conformal coating demands.
Acrylic is a viable alternative for parylene in certain applications where moisture protection is the primary focus. Acrylics offer excellent moisture protection and have an advantage of being easier to work and re-work than parylene. It is also a conformal coating option to be considered if cost is a paramount concern, as it is often the lowest price option.
It would not be a good choice to switch from acrylic conformal coating to parylene if your product was going to be subjected to solvents of any kind, as acrylics typically do not have strong protection against solvents, especially when compared to parylene.
Silicones are on the opposite end of the spectrum regarding thickness than parylene. Silicone conformal coatings are applied anywhere from .002” to .008” while parylene is generally applied .0005” to .002”. This added thickness can help products sustain operation in environments with large, rapid shifts in operating temperature.
Urethanes can be used instead of parylene for applications that require a rigid coating to meet certain abrasive tests. Urethane is a much harder coating than parylene and has the highest amount of chemical resistance of any conformal coating other than parylene.
You should really consider sticking with parylene if your product is going to be submerged in harsh solvents. The uniformity of parylene far exceeds anything that can be offered with a liquid conformal coating.
All things considered, the choice for a conformal coating ultimately depends on your particular application. When considering a conformal coating service provider, ensure that they offer multiple coatings. This way you are more likely to get the right coating for your application and not the only product that particular company offers.