Acrylic Coatings

Acrylic resin (AR) conformal coatings are one of the most common conformal coatings used today. The coatings are single-component materials; more specifically, they are pre-formed acrylic polymers that are dissolved in a solvent to be applied to surfaces. 

Acrylics provide an excellent barrier to both moisture and humidity and have good fungus resistance; these properties are why acrylic coatings are so frequently used on electronic circuitry. Acrylics conform to an electronic device’s shape, protecting the entire surface from moisture, electrical and physical issues, including gases, UV exposure, humidity, condensation and liquid. In addition, the coatings give off minimal to no heat during the curing process, which is beneficial for heat-sensitive electronics.

Acrylics are also nonconductive to withstand static discharge. These dielectric properties are advantageous for printed circuit board (PCB) applications since the coating can enhance the product’s capabilities by way of miniaturization; that is, board components and traces can be designed close together so that electrical components are as small as possible, allowing more components and capabilities per board assembly.

Acrylic Conformal Coating Process

Acrylic resins can be easily applied using one of three methods:

• Brush: Hand brushing is most appropriate for small scale batch productions, prototypes and anything that would otherwise require extensive masking in order to avoid coating. The operator brushes the acrylic coating onto the device with care to cover each side well.
• Spray: Spraying is the best technique for large quantities and provides the most accurate coating control. Small to mid-volume quantities can be coated using a spray gun, and robotic processes can automate coating for high-volume production needs.
• Dip: Dip coating is achieved by placing the assembly into a tank of coating. Manual or automated dip coating processes are available depending on the customer needs.

Post-coating, Acrylics dry to the touch within 10 minutes and typically cure completely within 24 hours at room temperature. Cure times can be decreased using thermal cure processes.  Unlike epoxies, acrylics do not shrink during the cure process, and they give off little to no heat.

Rework of Acrylics

Due to their low chemical resistance, acrylics are ideal when components need to be removed or reworked with high frequency.