Cracking in Conformal Coating

Cracking in conformal coating occurs when the cured film fractures, creating fissures that expose the PCB surface. These cracks undermine protection, allowing moisture and contaminants to penetrate and reduce electrical insulation performance.

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Collage of conformal coating cracking defects on PCB surfaces under UV and visible light inspection

What is Cracking in Conformal Coating?

  • Definition: Surface fractures and fissures in the cured film that can expose the underlying board.
  • Main issue: Cracks create moisture/leakage pathways, compromise insulation resistance, and can propagate under thermal or mechanical stress.

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Causes of Cracking in Conformal Coating

  • Excess cure temperature or fast ramp — high thermal stress induces fracture.
  • Insufficient RT flash — trapped solvent leads to embrittlement after bake.
  • Excessive film build — internal stress and CTE mismatch at edges/components.
  • Inflexible chemistry — coating Tg/elongation not suited to service conditions.
  • Harsh environment — thermal cycling, vibration, or shock causing fatigue.

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How to Prevent Conformal Coating Cracking

  • Reduce cure stress — lower initial oven setpoints and use controlled ramps.
  • Allow RT drying — adequate flash-off to remove solvent before heat cure.
  • Optimise thickness — keep film within supplier windows; avoid puddling.
  • Match material to duty — select chemistries with suitable Tg and elongation.
  • Validate profiles — thermal shock/cycling trials to de-risk the recipe.

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Troubleshooting & Diagnosis

  • Microscopy & mapping — identify crack patterns (edge, across pads, component bodies).
  • Thickness verification — coupon and feature checks to find over-build zones.
  • Cure review — confirm flash-off duration and oven profile (ramp/soak/peak).
  • Material check — verify batch age, viscosity/solids; compare flexibility specs.
  • Environmental testing — expose samples to thermal cycling/vibration to replicate failure.

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Where Cracking Sits Among Other Defects

Cracking is primarily a stress/material issue linked to cure, thickness, and service loads. By contrast, delamination is an adhesion/cure problem, de-wetting is surface energy/contamination, and orange peel is flow/level. Addressing the correct mechanism prevents recurrence and protects long-term reliability.

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Training on Conformal Coating Defects & More

SCH offers conformal coating training that goes beyond theory—recognising and preventing cracking, delamination, de-wetting, orange peel, pinholes, bubbles, foam, and wicking. We cover process analysis, troubleshooting, materials, 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:
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Conformal Coating Processes Hub
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Equipment & Application Methods Hub
Configure application equipment—spray guns & booths, dip systems, and selective valves/robots. Standardise recipes and fixtures to stabilise throughput and yield.

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Inspection & Quality Hub
Build a robust inspection & quality plan: UV coverage checks, thickness verification (AQL, coupons, SPC), adhesion tests, and documentation aligned to IPC/UL.

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Removal & Rework Hub
Choose the right removal & rework method: wet stripping for liquid coatings, precision micro-abrasion for Parylene, and controlled repair workflows that protect pads & leads.

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Parylene Coating Hub
Dive into Parylene coating: dimer grades, deposition parameters, vapour-phase masking, and optical thickness control. See when Parylene outperforms liquid coatings.

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Defects & Failure Mechanisms Hub
Prevent common coating defects—pinholes, de-wetting, orange peel, cracking, delamination, corrosion/ionic contamination, and wicking—with root-cause fixes.

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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 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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