Orange Peel in Conformal Coating

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Orange peel is a surface texture defect where the cured conformal coating develops a rough, dimpled finish (like orange skin). It is usually a flow/levelling issue linked to viscosity, film build, spray setup, flash-off and cure behaviour.

If you’re looking for the complete list of conformal coating defect types and failure mechanisms, use the hub overview: Conformal Coating Defects Hub.

For wider application stability and control windows (methods, repeatability and process discipline), see the Conformal Coating Processes Hub.

📄 Download: Orange Peel defect bulletin (PDF)

Article Quicklinks

Topic	More
Definitions: what orange peel is and why it matters	🔗
Root Causes of orange peel	🔗
Prevention: viscosity, passes, setup	🔗
Troubleshooting & Diagnosis	🔗

What is Orange Peel in Conformal Coating?

• Definition: An uneven, textured surface that appears dull and resembles orange skin.
• Why it matters: Orange peel is often a sign the film did not level correctly. In real products this can create local thin areas, inconsistent edge build, and a less robust moisture barrier in demanding environments.
• Common “look” on the line: a uniform pebbled texture, sometimes worse in high-airflow zones, around tall components, or where the spray pass is “dry”.

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Causes of Orange Peel in Conformal Coating

• • Spray distance / excessive flash in-flight — droplets partially dry before reaching the PCB, so the deposited film cannot merge and level.
  • Over-atomisation / too much air — excessively fine droplets and high air shear increase solvent loss and create a “dry spray” texture.
  • Viscosity too high / solids too high — the film resists flow-out; the surface “freezes” before levelling completes.
  • Film build too low — too little wet film to self-level (common with aerosols, fast passes, or overly conservative settings). A thin, partially dried film often locks in texture.
  • Flash-off / cure profile issues — insufficient flash-off before heat cure, or an oven profile that skins too quickly (rapid early ramp, high initial setpoint) prevents levelling and traps texture.
  • Airflow and booth conditions — high extraction/air velocity, low temperature, or low humidity can accelerate surface drying and promote orange peel (especially on edges/high points).
  • Surface tension gradients — mixed substrates (solder mask vs metals/plastics) or mild contamination can change wetting/flow locally and exaggerate texture at boundaries.
  • Sanity check (look-alikes): If you see craters/islands/bare patches, route to de-wetting. If you see voids/pits rather than texture, route to pinholes, bubbles & foam. If the surface is rough because the film has micro-cracked, route to cracking.

To verify finish, thickness and coverage acceptance criteria, use a defined inspection plan from the Inspection & Quality Hub.

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How to Prevent Orange Peel in Conformal Coating

• Adjust viscosity — reduce to a stable target window so the coating can level (stay within supplier limits and document the control range).
• Optimise spray setup — correct gun distance, head/nozzle selection, and balanced atomising/flow pressures (avoid “dry spray” conditions).
• Build film correctly — multiple controlled passes with defined flash-off rather than one dry, under-built pass.
• Control booth airflow and conditions — avoid excessive extraction directly over the wet film; keep temperature stable to avoid rapid surface skinning.
• Allow adequate flash-off — give solvent time to escape before heat cure (especially in thicker areas and around tall components).
• Re-profile cure — verify oven ramp/soak matches supplier guidance and allows levelling before the film “locks”.
• Lock a recipe — once stable, record parameters (distance, speed, overlap, pressures, viscosity, flash, cure) and control them with audits and pattern boards.

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Troubleshooting & Diagnosis

• Pattern boards / UV + white-light inspection — verify finish uniformity, edge definition, and whether texture tracks airflow zones or gun pass direction.
• Viscosity & solids checks — confirm the material is in the qualified window; monitor solvent loss and document adjustments.
• Spray setup validation — record head type, gun distance, fan width, and pressures (then lock as a recipe).
• Airflow check — assess extraction position/velocity and local drafts that can “dry” the film during deposition/flash.
• Pass strategy — shift toward multiple controlled passes with defined flash-off rather than fast, dry passes.
• Cure profile review — ensure progressive ramping so the film levels before skinning; verify with profiling tools, not just oven setpoint.

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📄 Download the PDF bulletin

Looking for Other Defect Types?

This page focuses specifically on orange peel. For the complete index of defect types and links to each technical article, use the hub overview:

Explore the Defects Hub ↗

Training on Conformal Coating Defects & More

SCH offers conformal coating training that goes beyond theory—recognising and preventing orange peel, pinholes, bubbles, foam, de-wetting, delamination, and cracking. We cover process analysis, troubleshooting, materials selection, NPI and application methods.

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Industry Standards We Work To

SCH Services follows international standards across all our coating services, training, equipment supply and materials. Our processes are aligned to the relevant IPC standards, including:

• IPC-A-610 – Acceptability of Electronic Assemblies
• IPC-CC-830 – Qualification & Performance of Conformal Coatings
• IPC-HDBK-830 – Conformal Coating Handbook (guidance and best practice)

For further details on IPC standards, visit:
electronics.org/ipc-standards ↗

Why Choose SCH Services?

Partnering with SCH Services means more than just outsourcing — you gain a complete, integrated platform for Conformal Coating, Parylene & ProShieldESD Solutions, alongside equipment, materials, and training, all backed by decades of hands-on expertise.

• ✈️ 25+ Years of Expertise – Specialists in coating technologies trusted worldwide.
• 🛠️ End-to-End Support – Guidance on coating selection, masking, inspection, and ProShieldESD integration.
• 📈 Scalable Solutions – From prototype to high-volume production.
• 🌍 Global Reach – Support across Europe, North America, and Asia.
• ✅ Proven Reliability – Built on quality, consistency, and customer satisfaction.

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Note: This article provides general technical guidance only. Final design, safety, and compliance decisions must be verified by the product manufacturer and validated against the applicable standards.