Once you’ve selected the proper conformal coating for your purpose, is time to apply the conformal coating to the board. There are two main methods for applying conformal coating spraying and dip coating. Spraying can be further divided into aerosol application, spray gun application and automatic dispensing. We will demonstrate aerosol spray coating.
Before coating circuit board, make sure it's clean and free of anything that would affect the adhesion of the conformal coating such as oil or residual flux. Once you're satisfied the circuit board is completely clean is time to coat. Place the board in a well ventilated area apply top to bottom allowing the coating to flow evenly around the components. Rotate the circuit board 90 degrees and repeat the application rotate and apply the coating two additional times and allow the board to cure.
Now that our boards have been properly coated and allowed to cure, let's talk about the differences in coating characteristics.
The first conformal coatings will discuss are the KON FORM SR and the KON FORM SR high viscosity our silicone conformal coatings. These conformal coatings are moisture cured products that require at least 50 percent humidity and good airflow to cure properly at room temperature. The resulting film is wax like in appearance and texture it's a protective coating, but it's sensitive to abrasion. The coating can be scratched with a hard object and imprinted if enough pressure applied like this.
KON FORM AR and KON FORM ULTRA are acrylic conformal coatings. They’re cured through an evaporation drying process to form a rigid clear film. KON FORM AR takes approximately 30 minutes to dry tack free, while KON FORM ULTRA takes approximately 10 minutes to dry tack free.
These conformal coatings are more resistant to abrasion but are sensitive to solvents, they have easy removal properties however the dielectric properties of these materials are outstanding.
KON FORM FLEX COAT gives a clear coat upon appearance, is abrasive sensitive, but in a different way than KON FORM SR. KON FORM flex coat contains elastic characteristics similar to a latex temporary mask. The product can be peeled from the boards allowing easy removal on large components. KON FORM FLEX COAT dries tack free in 10 minutes.
KON FORM HR & KON FORM UR-A are both water based conformal coatings. They offer tough, urethane based protection making them superior for abrasion resistance and greatly reduced in VOC exposure. However these materials take several weeks to cure. KON FORM HR and KON FORM UR-A are only available in liquid form. In order for conformal coating to work effectively, the entire board must be coated. Each of our conformal coatings contain a UV indicator that allows us to inspect the board visually to determine if the board has been completely coated.
The inspection process is simple turn on the UV light to the fluorescent analysis chamber, place the circuit board inside the chamber, then inspect by looking through the view at the top of the chamber. You should see a continuous blue image across the circuit board, this process can also be used to inspect the board after the conformal coating removal to ensure all the coating has been removed. When in doubt consult our product selection guide to help choose which product will fit your production requirements and your final production performance needs. Conformal coatings provide excellent protection from environmental contamination, dielectric surges and other challenges that could damage circuit board components. By choosing the right conformal coating, you'll increase the life and performance of your circuit boards.