Conformal Coating Spraying with a Spray Gun

Conformal coating spraying using a conventional or HVLP spray gun remains one of the most widely adopted processes. When applied correctly, spray coating delivers uniform films, strong edge coverage, and reliable PCB protection across complete-coverage applications.

What Is Conformal Coating Spraying?

In a complete-coverage spray process, conformal coating is atomised and deposited evenly across the whole PCB, excluding masked keep-outs. The atomised particles adhere to surfaces, forming a continuous protective film. When controlled correctly, this ensures good edge coverage and a professional finish.

When to Choose Conformal Coating Spraying

  • Compared to dip coating: Dip is efficient but often impractical where many keep-outs exist. Spraying reduces masking effort and total labour cost.
  • Compared to selective robots: Selective coating targets only required areas. Spraying is ideal for complete coverage, delivering a uniform protective layer. It’s also a lower cost solution for lower volumes.

Equipment & Setup for Spray Guns

  • Gun type: HVLP or compliant spray gun with a fine atomising cap for low-viscosity coatings.
  • Nozzle & pressure: Match nozzle size to coating viscosity. Use the lowest atomising pressure that gives a fine, even fan.
  • Material preparation: Mix according to datasheet, filter before use, and check viscosity and temperature for repeatability.
  • Booth controls: Maintain stable airflow and good extraction to avoid overspray contamination.

See our CB100 conformal coating spray booth for a cost -effective solution to application.

Spray Technique: Distance, Overlap & Pass Strategy

  • Gun distance & angle: Keep a consistent standoff and hold the spray perpendicular for even coverage.
  • Fan pattern & overlap: Use a stable fan and overlap strokes to avoid striping or uneven film build.
  • Passes & flash: Apply multiple light passes with flash-off time between coats to avoid runs.
  • Edge and feature coverage: Apply a light “pre-wet” pass to edges before building up the full coating thickness.

We offer comprehensive conformal coating training including spray application. Contact us now.

Masking in Spray Processes

Even with complete-coverage spraying, connectors, test points, and mechanical keep-outs usually require masking. Use masking boots, precision tapes, or custom fixtures to reduce de-masking time and improve repeatability.

Find out more about our unique conformal coating masking solutions that we use in our own subcontract coating services.

Quality Control & Acceptance

  • Thickness verification: Check film thickness using wet or dry methods appropriate to the coating and substrate.
  • Inspection: Verify uniformity, coverage of edges, and absence of holidays, runs, or orange peel under white light and UV.
  • Cure: Follow datasheet guidelines for flash-off and curing before handling or electrical testing.

For more detailed guidance on coating inspection and acceptance, see the IPC-A-610 Acceptability of Electronic Assemblies standard.

Cost & Scalability: Aerosols vs Spray Booth

Aerosol cans are useful for very low volumes or prototypes. For ongoing production, dedicated spray guns and booths are more economical, more consistent, and deliver a higher-quality finish. Once aerosol use exceeds around ten cans per month, a spray booth process is typically more cost-effective.

Common Defects & How to Fix Them

  • Runs or sags: Reduce wet coat thickness, increase flash time, and keep a steady gun distance and speed.
  • Orange peel: Adjust atomising pressure and viscosity; avoid spraying too far from the surface.
  • Poor edge coverage: Apply light pre-wet passes on edges before the main coating passes.

Need help with your conformal coating defects or process problems. We provide troubleshooting, optimisation and benchmarking consultancy to help you solve your issues.

Need Help With Conformal Coating Spraying?

We provide subcontract spraying, process setup, operator training, and equipment supply to ensure your conformal coating process meets thickness, reliability, and production requirements.

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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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