Orange Peel in Conformal Coating

Orange peel in conformal coating is a surface defect where the cured coating develops a textured, uneven finish that looks like the skin of an orange. This defect can reduce coating thickness and compromise PCB protection.

Orange peel effect in conformal coating on PCB surface under UV inspection

What is Orange Peel in Conformal Coating?

  • Definition: An uneven, textured surface that appears dull and looks like the skin of an orange.
  • Main Issue: The conformal coating layer may be too thin in places to provide adequate protection.

Causes of Orange Peel in Conformal Coating

  • Improper spray application – coating applied too far from the PCB dries before it can level.
  • Incorrect thickness – insufficient coating deposited to self-level.
  • Viscosity too high – coating cannot flow out smoothly.
  • Poor cure profile – inadequate flash-off before heat cure or oven misprofiled.

How to Prevent Orange Peel in Conformal Coating

  • Adjust viscosity – reduce viscosity so the coating can level out.
  • Optimise spray setup – reduce air pressure and set correct spray distance per material guidelines.
  • Apply sufficient coating – especially when using aerosols, ensure enough passes for a level finish.
  • Allow flash-off – extend solvent evaporation time before heat cure.
  • Check cure profile – re-profile the oven using the supplier’s recommended settings.

Conformal Coating Defects and Their Importance

Conformal coating protects printed circuit boards (PCBs) against moisture, dust, corrosion and electrical leakage.
However, defects such as orange peel, pinholes, bubbles, foam, de-wetting, delamination, and cracking
can compromise that protection. Even small imperfections provide pathways for contaminants, lower insulation resistance, and increase the risk of premature failure.

These coating defects arise from issues such as incorrect viscosity or film thickness, trapped air or solvent,
poor surface preparation, unsuitable spray settings, or stress during cure. For example, orange peel is often caused by incorrect viscosity or spray setup, while pinholes and bubbles are linked to air entrapment or solvent skinning. De-wetting points to contamination or low surface energy, and delamination highlights adhesion or curing problems.

Understanding these failure mechanisms is essential for process control, quality assurance, and long-term reliability. By recognising how and why these defects form, manufacturers can optimise application methods, materials, and operator technique to eliminate rework, improve yield, and ensure consistent performance.

This section provides a practical overview of the most frequent conformal coating defects, linking symptoms to likely causes and offering guidance on how to diagnose, prevent, and correct them in production.

Training on Conformal Coating Defects & More

SCH offers conformal coating training that goes beyond theory. Our courses teach you how to recognise and prevent defects such as orange peel, pinholes, bubbles, foam, de-wetting, delamination, and cracking. We also cover process analysis, troubleshooting, materials, and application methods.

Explore Conformal Coating Training →

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 by aerospace, medical, defence, automotive, and electronics industries worldwide.
  • 🛠️ End-to-End Support – Guidance on coating selection, Parylene grades, masking strategies, application methods, inspection, and ProShieldESD integration.
  • 📈 Scalable Solutions – From small prototype batches to full-scale, high-volume production, SCH delivers flexible capacity that grows with your needs.
  • 🌍 Global Reach – Responsive technical support and supply coverage across Europe, North America, and Asia.
  • ✅ Proven Reliability – A strong reputation built on quality, consistency, and customer satisfaction across services, equipment, and materials.

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