What is PCBA Conformal Coating?

1.What is PCBA Conformal Coating?

PCBA conformal coating is a specialized protective layer applied to printed circuit board assemblies (PCBAs). It shields electronic assemblies from harsh environmental exposure while maintaining thermal stability across extreme temperatures. The cured coating forms a transparent elastomeric film with insulation properties, moisture resistance, dust mitigation, and corrosion protection.

2.Features of Conformal Coating

Conformal coating is a single-component coating formulated with high-performance, aging resistance insulating polymers as the base material, along with flame retardants and other components. Its main features include: low viscosity, quick drying, water resistance, no corrosion, good adhesion, insulation, anti-aging, flame retardancy, and being harmless to the human body during use. After curing, it forms a transparent elastic film with a beautiful appearance, which can be repaired and does not interfere with the rework of the circuit board.

3.Types of Conformal Coating

3.1Acrylic Resin (AR)

Acrylic conformal coatings provide good elasticity and general protection. They are noted for their high dielectric strength, good moisture resistance, and wear resistance. Acrylic coating can be removed quickly and easily using common solvents, no need agitation.

3.2Epoxy Resin (ER)

Epoxy conformal coatings are characterized by high hardness,  strong adhesion and excellent chemical corrosion resistance. However, rework is difficult due to their high brittleness and poor impact resistance.

3.3 Polyurethane Resin (UR)

Polyurethane conformal coatings offer excellent moisture resistance, chemical resistance, and wear resistance. As solvent resistance, this coating is very difficult to remove. For complete removal, requires specialized solvents, prolonged soaking times, and agitation using brushed or ultrasonic baths.  

3.4 Silicone Resin (SR)

Silicone conformal coatings deliver excellent protection across a wide temperature range. SR coating has good chemical resistance, moisture resistance, and salt spray resistance, and is very flexible. Silicone conformal coatings are not wear-resistant, but enable them to resist vibration stress. Silicone coatings are typically used in high-humidity environments. For complete removal, requires specialized solvents, prolonged soaking times, and agitation using brushed or ultrasonic baths.  

3.5 Fluoropolymer (FP)

Fluoropolymer coatings offer outstanding resistance to chemical corrosion (resistant to strong acids, alkalis, and solvents), low surface tension (water-repellent and oil-repellent), but high cost and a complex coating process.

4.Conformal Coating Application Methods

Conformal coating can be applied via brushing, spraying, and dipping process. The main application requirements:

* Recommended thickness is between 0.1 and 0.2mm;

* Surfaces must be cleaned of moisture and contaminants before coating;

* The second coat can be applied after the first coat dry;

* Operations require adequate ventilation for solvent evaporation;

* Operators must wear protective masks.

5.How To Choose Conformal Coating for Your PCBA Projects?

Conformal coating selection should consider four key factors:

5.1Environmental operating conditions

5.2Manufacturing process compatibility

5.3Cost-effectiveness

5.4Reliability requirements.

For example, in situations where quick curing is required, a quick-drying type of anti-corrosion paint can be chosen. While in some fields with higher environmental protection requirements, an environmentally friendly coating with low VOC (volatile organic compounds) emissions should be selected.