Acrylic conformal coatings are perhaps the most popular of all conformal coating materials as they are easy to apply and remove, with a wide process window for use. Acrylic coatings dry rapidly, are fungus resistant and provide long pot life. Additionally, acrylic materials produce little or no heat during the curing process, eliminating potential damage to heat sensitive components. The coatings possess low shrinkage, provide significant humidity resistance and exhibit low glass transition temperatures.
Acrylic resin is sprayed on a printed circuit board that conforms to the contours of PCB to protect its components from several types of contamination. An assembly cleaned PCB should go through the conformal coating process to increase its performance lifetime and durability. Note that the PCB should be cleaned after manufacturing and assembly and before applying any conformal coating as the containments will get locked on the surface of the board a may cause problems that could even lead to the device failure.
What is Acrylic Conformal coating?
It is a fast-drying acrylic component, that is strongly adhesive and is highly protective against moisture and environmental protection for assembled and installed circuit boards. This acrylic resin is free from xylene i.e. Any of a group of three isomeric aromatic hydrocarbons, di-methyl-benzene, found in coal and wood tar.
The one-layer acrylic conformal coating gives a high-quality finishing, is easy to use, and does not require any special equipment for application on the PCB. The acrylic material provides excellent strength, stiffness, and optical clarity. It can especially deal with a high moisture environment, dirt, dust. It can also protect the PCB from a wide range of irregular temperatures, and short circuits that could potentially corrode and destroy the PCB. Acrylic conformal coating maintains high flexibility and electric properties. This coating on the topology of the PCB is fluorescent under UV light for easy inspection in case of any fault and is easily repaired. It can be applied by simple spraying, brushing, or dipping methods.
Why Use Acrylic Conformal coating?
The specialty of acrylic conformal coating spray is that it solidifies very rapidly and provides total protection from any type of containment. Before application, the surface must be free of moisture, dirt, wax, glue, grease, flux, or any other kind of containment.Acrylic conformal coating sprays are generally more economically beneficial and it is easy to apply and remove it from the PCB. Although it doesn’t offer much protection from chemical exposure, it provides a high dielectric withstand voltage. Acrylic conformal coating easily dissolves in solvents so rework and repairing are easier. What generally distinguish acrylic conformal coating from other resin coating is its ease of removal.The acrylic coating is easy to remove by a variety of solvents, often without the need for agitation. But it does not provide resistance against chemical vapors.
The acrylic conformal coating is considered as the basic entry-level protection because they are economical and easy to remove. It also protects the PCB against a broad category of containments, and specialize only in dielectric strength. There is a massive selection of products that can meet the expectations of the customer’s mechanical and electrical environmental requirements. Its total moisture protection mechanism makes it ideal for industrial devices that operate in humid and moist environments.
Properties of Acrylic Conformal Coating
Acrylic conformal coating is known for its high dielectric strength and high moisture absorbing resistance. Its easy removal properties distinguish it from other resin coatings, acrylic coatings are easily and quickly removed using a variety of solvents, often without the need of agitation. This makes the rework and even field repair much easier and practical. During the curing process, this coating produces no heat and provides a safe environment to the heat-sensitive components.
The acrylic conformal coating dries up rapidly, it takes 5-10 seconds to dry to touch after application. This makes the PCB fungus resistant and provides long container life. In addition to its properties, the conformal coating possesses low shrinkage, once it’s dried it acts as a solid component applied on the PCB, and also, its state transition temperatures are significantly stable. There is a variety of types of conformal coating that are available in the market, the user should perform adequate testing to confirm compatibility between the conformal coating and their particular assembly materials (PCB mainly) process conditions, and cleanliness level.