Conformal Coating PCB Guide: Types, Standards & When to Use It

What Is Conformal Coating?

Conformal coating is a thin polymeric film applied to a finished PCB assembly to protect it from moisture, dust, chemicals, temperature extremes, and mechanical stress. The coating "conforms" to the contours of the board and its components, providing a protective barrier without significantly adding weight or bulk.

Conformal coating is governed by IPC-CC-830, "Qualification and Performance of Electrical Insulating Compound for Printed Wiring Assemblies," which defines qualification test requirements for coating materials.

Conformal Coating Material Types

Application Methods

The choice of application method affects coating thickness uniformity, coverage of complex geometries, and production throughput:

• Spray (manual or automated): The most common method. Automated selective spray systems can coat specific areas while avoiding connectors and test points. Typical thickness: 25–75 µm.
• Dip coating: The entire board is dipped into the coating material. Provides excellent coverage of complex geometries but requires masking of all areas that must remain uncoated.
• Selective coating (robotic): A programmable robotic system applies coating precisely to defined areas. Minimises masking labour and waste. Kingdta uses selective coating systems for production runs.
• Brush coating: Manual application for small areas or rework. Not suitable for production.
• Vapour deposition (Parylene): Parylene is deposited in a vacuum chamber, producing a perfectly uniform, pinhole-free coating. Requires specialised equipment and is more expensive than other methods.

Masking Requirements

Areas that must not be coated include:

• Edge connectors and card-edge fingers
• Test points and ICT pads
• Mounting holes and press-fit connector areas
• Heat sink mounting surfaces
• Any area requiring electrical contact after assembly

Provide a masking drawing (PDF or DXF) with your assembly order, clearly marking all areas to be masked. Kingdta's engineers will review the masking requirements and confirm before production.

When Does Your Design Need Conformal Coating?

Conformal coating is required or strongly recommended in the following scenarios:

• Outdoor or high-humidity environments — any product exposed to condensation, rain, or humidity above 85 % RH
• Automotive underhood — temperature cycling from −40 to +125 °C with potential exposure to oil, fuel, and cleaning agents
• Marine and industrial — salt spray, chemical exposure, or heavy particulate contamination
• Medical devices — protection against sterilisation chemicals and body fluids
• High-altitude aerospace — low-pressure environments where corona discharge is a risk on high-voltage boards

Ordering Conformal Coating from Kingdta

Kingdta offers acrylic (AR), silicone (SR), and polyurethane (UR) conformal coating via automated selective spray systems. Parylene coating is available through our qualified subcontractor network. To order, include the following in your purchase order:

• Coating material type (AR / SR / UR)
• Target thickness (µm) or reference to IPC-CC-830 qualification class
• Masking drawing (PDF) with all excluded areas clearly marked
• UV inspection requirement (all acrylic coatings are UV-fluorescent by default)

Contact info@kingdta.com for a conformal coating quote or to discuss your specific requirements.