PCB Technical - Be aware of these conformal coatings to protect PCB and electronic components

Common types of conformal coatings

Conformal coating is a specialty polymerized film forming material used to protect printed circuit boards, components, and other electronic components from adverse environmental conditions caused by corrosive air, humidity, heat, fungi, and contaminants such as dust and dirt.

There are five common types of conformal coatings. How to choose the right paint for your application?

Acrylic adhesive

Acrylic adhesives are readily soluble in many organic solvents, thus facilitating the completion of circuit board repair work, and generally provide only selective resistance. Acrylic adhesive has the advantages of quick drying, good mildew resistance, no shrinkage during curing and good moisture resistance. But the disadvantage lies in low wear resistance, easy to be scratched, broken and peeling.

Epoxy resin, two components

Epoxies are usually two-component compounds that are mixed and begin to cure. Epoxy resin has good abrasion resistance and chemical resistance, as well as reasonable moisture resistance. But the paint is difficult to remove and rework. Since film shrinkage occurs during polymerization, the use of buffers around precision components is recommended. Curing at low temperature can reduce shrinkage to.

Polyurethane (pu)

Polyurethane has good moisture resistance and chemical resistance. Because of its good chemical resistance, the removal of paint requires the use of a stripping agent (which may leave an ionic residue). These residues may need to be thoroughly cleaned to prevent floor corrosion. Polyurethanes can be reworked by welding, but often produce brownish residues that affect the appearance of the product.

silicone

Silicone is usually a single compound that begins to cure when exposed to moisture in the air and at a certain temperature. Silicone has good wettability and adhesion after curing on all surfaces of electronic materials or modules. Can be widely used in high temperature (& GT; 120 degree Celsius), moisture sensitive, chemical resistance, corrosion resistance, anti-fungal environment.

Ethyl carbamate

Ethyl carbamate has strong protection, hardness and high solvent resistance, providing excellent wear resistance and low moisture permeability. In addition, it has good low temperature adaptability, but does not work well at high temperatures, and most cannot be repaired or reworked.