How to choose the right conformal coating for PCBs
A conformal coating protects populated boards against moisture, dust and condensation. This guide compares the acrylic, urethane, silicone and parylene chemistries, explains the application methods and frames the requirements of IPC-CC-830.
View soldering guidesWhich coating chemistry suits which assembly?
The chemistry decides protection level, temperature range and reworkability. Acrylics (AR) are easy to apply and can be removed with solvents, whereas urethane (UR), silicone (SR) and parylene are far more rugged but much harder to rework.
Acrylic gives solid moisture protection and fluoresces for optical inspection under UV light. Urethane resists solvents and abrasion, silicone covers the widest range at -65 to 200 °C, and parylene is deposited as an ultra-thin, pinhole-free film in a vacuum.
Which application method is right?
The options range from a manual brush to robotic selective coating. Volume, the required edge coverage and which components must be masked all drive the choice.
- Brush and aerosol spray: ideal for prototypes, repair and small batches.
- Dip coating: uniform film for medium volumes, needs extensive masking.
- Selective coating: a robot applies only defined areas and saves masking.
- Parylene: chemical vapour deposition in a vacuum wets every edge without gaps.
- Target thickness is usually 25‑75 µm, thicker for silicone and much thinner for parylene.
What does IPC-CC-830 require?
IPC-CC-830 is the qualification and performance standard for conformal coatings on populated boards. It defines tests for insulation resistance, moisture and thermal cycling, dielectric withstand and fungus resistance.
Workmanship and the acceptable defect criteria (bubbles, fisheyes, edge pull-back) are covered by IPC-A-610. Film thickness for acrylic, urethane and silicone is usually specified at 25 to 75 µm.
Frequently asked questions
How thick should a conformal coating be?
For acrylic, urethane and silicone, IPC-CC-830 typically specifies 25 to 75 µm dry film thickness. Parylene is much thinner (a few µm) and silicone is often applied a bit thicker.
Which coating is easiest to repair?
Acrylics can be dissolved locally with suitable solvents and recoated. Urethane and especially parylene are hard or impossible to rework.
Must the assembly be cleaned before coating?
Yes. Flux and ionic residues under the coating cause delamination and electromigration. No-clean processes should be verified for coating compatibility.
What does IPC-CC-830 mean?
It is the standard defining requirements and test methods for conformal coatings on electronic assemblies, including insulation resistance, thermal cycling and dielectric withstand.
Looking for the right conformal coating?
We advise on acrylic, urethane, silicone and parylene plus the matching application method - aligned with IPC-CC-830.
To IPC-CC-830
We recommend qualified, tested coating systems.
Right chemistry
Acrylic, urethane, silicone or parylene per application.
Process reliable
Guidance on cleaning, masking and film thickness.
Expert advice
Our specialists support your selection.