Orange Peel in Conformal Coating

← Back to Defects Hub
← Knowledge Hub

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

For the complete index of defect types and links to each article, use the Conformal Coating Defects Hub.

📄 Download:
Orange Peel defect bulletin (PDF)

Article Quicklinks

Topic	More
Definitions: what orange peel is and why it matters	🔗
How it forms: mechanisms & “tell-tale” signs	🔗
Root Causes: process, material, equipment, airflow	🔗
Prevention: control window & recipes	🔗
Troubleshooting & Diagnosis: isolate the mechanism	🔗
Repair: when to accept, touch-up vs strip & recoat	🔗

What is Orange Peel in Conformal Coating?

• Definition: a rough, dimpled, pebbled surface texture (often dull) caused by incomplete levelling of the wet film before it “locks”.
• Why it matters: orange peel is evidence the film didn’t flow out correctly. In real assemblies this can mean local thin areas, inconsistent edge build, and a less robust moisture barrier in demanding environments.
• Common on the line: a uniform pebbled texture, sometimes worse in high-airflow zones, around tall components, or where the spray pass is “dry”.

↑ Back to Quicklinks

How Orange Peel Forms (Mechanisms)

• Dry spray / pre-flash in-flight: droplets partially dry before reaching the PCB. The deposited film can’t merge into a continuous, smooth surface.
• Levelling stops too early: viscosity/solids too high or rapid surface drying means the film “freezes” before texture can relax.
• Low wet film build: there isn’t enough wet film thickness to self-level (common with aerosols, fast passes, or over-conservative settings).
• Airflow-driven skinning: extraction/drafts accelerate surface evaporation on edges/high points, locking in texture.
• Cure profile locks the surface: aggressive early heat or UV exposure can set the surface before flow-out completes.

Pattern clue: if the texture is worst where airflow is highest or in the direction of the spray pass, suspect dry spray / airflow / distance / atomisation. If you see craters/islands/bare patches, route to de-wetting.

↑ Back to Quicklinks

Root Causes of Orange Peel

Spray setup & technique

• Excessive spray distance → solvent flashes in-flight → “dry spray”.
• Over-atomisation / too much air → fine droplets + high shear → rapid solvent loss and texture.
• Imbalanced atomising vs fluid pressure → poor droplet coalescence and weak flow-out.
• Fast passes / low overlap → low wet film build → insufficient self-levelling.

Material condition

• Viscosity too high / solids too high → film resists flow and “freezes” early.
• Solvent imbalance (evaporation in pot/line) → increased texture risk and poor levelling.
• Surface tension gradients (mixed substrates or mild contamination) → uneven flow-out and exaggerated texture at boundaries.

Environment & cure behaviour

• High extraction / local drafts across the wet film → accelerated surface drying and skinning.
• Low temperature / unstable conditions → inconsistent evaporation and levelling.
• Flash-off / cure profile issues → inadequate flash before heat cure, or an oven ramp that skins too quickly.

Sanity check (look-alikes): 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.

↑ Back to Quicklinks

How to Prevent Orange Peel

Stabilise the control window

• Control viscosity: measure/record and keep within a validated range (manage solvent loss).
• Build wet film correctly: multiple controlled passes with defined flash-off rather than one dry, under-built pass.
• Control flash/cure behaviour: avoid rapid surface locking; use a profile that allows levelling before set.

Remove “dry spray” conditions

• Optimise gun distance: reduce excessive stand-off that causes in-flight flash.
• Balance pressures: avoid over-atomisation; match atomising and fluid settings to the head/nozzle.
• Lock a recipe: record distance, speed, overlap, head/nozzle, pressures, viscosity, flash and cure (then train/audit to it).

Manage booth airflow

• Avoid excessive extraction directly over wet film and reduce local drafts that “skin” the surface.
• Keep conditions stable so evaporation and levelling are repeatable across shifts.

↑ Back to Quicklinks

Troubleshooting & Diagnosis

1) Confirm the pattern (fastest win)

• White-light + UV inspection: confirm it is texture (not craters/voids) and map where it is worst.
• Correlation: does it track airflow zones, edges/high points, or gun pass direction?

2) Check the three big levers

• Viscosity/solids: verify the material is inside the validated window.
• Spray recipe: head/nozzle, distance, fan width, overlap, and pressures (compare to the known-good recipe).
• Airflow & flash/cure: look for skinning from drafts/extraction or early ramp/over-aggressive set.

3) Validate the fix with a controlled trial

• Adjust one variable at a time (distance, atomising pressure, viscosity, pass build, airflow).
• Pattern boards: keep a before/after reference set and record settings so the improvement is repeatable.

📄 If you want the condensed version for your team: download the PDF bulletin.

↑ Back to Quicklinks

Repair: When to Accept, Touch-Up vs Strip & Recoat

• Cosmetic-only texture: if thickness/coverage are compliant and acceptance criteria allow, orange peel may be acceptable.
• Risk indicators: if orange peel is accompanied by thin areas, poor edge definition, or marginal coverage in required zones, treat as a process defect.
• Robust correction: if the mechanism is “dry spray / locked film”, stripping and recoat is often the fastest route to a consistent finish (then fix the recipe so it doesn’t repeat).

For removal workflows and best-fit methods, see the Removal & Rework Hub.

↑ Back to Quicklinks

Looking for Other Defect Types?

This page covers orange peel. For the complete index of defect types and links to each technical article:

Explore the Defects Hub ↗

Training on Conformal Coating Defects

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.

Explore Conformal Coating Training ↗

Industry Standards We Work To

SCH Services aligns coating services, training, equipment supply and materials to 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:
electronics.org/ipc-standards ↗

Why Choose SCH Services?

You gain a complete, integrated platform for Conformal Coating, Parylene & ProShieldESD—plus equipment, materials and training—backed by decades of hands-on process support.

• 🛠️ End-to-End Support – Selection, masking, inspection and troubleshooting.
• ✅ Process Discipline – Recipes, control windows and repeatability.
• 🌍 Global Reach – Support across Europe, North America and Asia.

📞 Call: +44 (0)1226 249019   |   ✉ Email: sales@schservices.com |   💬 Contact Us ›

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.