Frequently Asked Questions (FAQs)

Our FAQs hub brings together the most common questions on conformal coating, Parylene, cleaning, masking, equipment, materials, and services. Expand a category to explore concise answers, then follow the suggested link targets to dive deeper.

Illustration of a PCB with question and answer speech bubbles, symbolising FAQs on conformal coating, Parylene, and ProShieldESD

FAQ Categories

Fundamentals

What is conformal coating?
A thin polymer film (10–100 µm) applied to PCBs to protect against moisture, dust, and electrical leakage.
→ Conformal Coating Solutions
Why is conformal coating used on PCBs?
It improves reliability, prevents corrosion, and extends product life in harsh conditions.
→ Conformal Coating Solutions
What industries use conformal coating?
Conformal coatings are widely used across many industries, including aerospace, automotive, defence, energy, medical, and industrial electronics, where they play a vital role in ensuring long-term reliability.
→ Industries overview
What’s the difference between conformal coating and potting?
Coating is thin, lightweight and reworkable; potting is a thick resin mass for extreme protection.
→ Conformal Coating Solutions
What international standards apply to coatings?
Commonly IPC-A-610, IPC-CC-830, IEC 60664, MIL specs and customer-specific requirements.
→ Conformal Coating Training
What is pollution degree classification?
A rating (PD1–PD4) of environmental contamination that affects insulation design and coating needs.
→ Industrial Solutions
How thick should a conformal coating be?
Liquid conformal coatings are typically applied at 25–75 µm, while Parylene is 5–25 µm. IPC-CC-830 and IPC-A-610 specify acceptable thickness ranges and require measurement on coated test coupons for verification.
→ Film Thickness Measurement
Do coatings affect circuit performance?
They raise surface insulation resistance and reduce leakage; added capacitance is negligible at normal thicknesses.
→ Conformal Coating Solutions

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Cleaning & Reliability

Should I clean my PCB before conformal coating?
Yes. Flux and ionic residues can cause poor adhesion, dewetting, and long-term failures.
→ Cleaning Services
Can I coat a PCB that is “no-clean”?
Possibly, but many specs still mandate additional cleaning; “no-clean” residues may still impair adhesion.
→ Conformal Coating Solutions
What happens if I don’t clean before coating?
It is possible to apply conformal coating over no-clean assemblies, but the process demands much tighter controls. Flux residues must be minimal and consistent, and you’ll need strict validation of cleanliness, adhesion, and long-term reliability to avoid defects.
→ Defects Solutions
How clean should a PCB be before coating?
Align to IPC cleanliness expectations (e.g., ionic contamination limits) verified by ROSE or ion chromatography.
→ Training: Cleaning & Reliability
What cleaning methods are used pre-coating?
Aqueous spray-in-air, vapour degreasing, ultrasonic, plasma—selected by contaminant type and assembly design.
→ Training: Cleaning & Reliability
How do you test PCB cleanliness?
ROSE testing, ion chromatography and SIR testing confirm ionic and reliability performance.
→ Cleaning & Reliability
Can SCH provide cleaning as a standalone service?
Yes—pre-coating cleaning and ionic testing offered standalone or integrated with coating services.
→ Cleaning Services
Does cleaning add cost to the coating process?
It adds process time/cost but typically lowers rework and field failure risk—reducing total cost of ownership.
→ Cleaning Services

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Processes & Methods

What are the main application methods?
Spraying, dipping, brushing, robotic selective coating, and vapour deposition (Parylene).
→ Coating Equipment overview
How do spraying and dipping compare?
Spraying suits complex geometries; dipping gives fast, uniform coverage for high volume.
→ Dip Coating Systems
What is vapour deposition?
A vacuum CVD process for Parylene that coats all exposed surfaces with pinhole-free films.
→ Parylene Solutions
How do coatings cure?
By solvent evaporation, heat, UV, or moisture-activated cross-linking depending on chemistry.
→ Drying Cabinets (CB100)
Why is cleaning vital before coating?
Surface residues lower surface energy and trigger defects like dewetting or poor adhesion.
→ Cleaning Services
How do you measure coating viscosity?
Zahn/Ford cups or inline sensors to maintain consistent application parameters.
→ Training: Process Control
What inspection methods are used?
UV inspection & magnification for validation and root cause analysis.
→ Inspection Booths (IB100)
Can conformal coating be automated?
Yes—selective robots improve consistency, reduce labour and control deposits precisely.
→ Selective Coating Equipment
What are common process challenges?
Bubbles, bridging, shadowing and uneven thickness; solved by setup, viscosity and masking optimisation.
→ Training: Troubleshooting Defects

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Parylene Coating

What is Parylene?
A vacuum-deposited polymer offering uniform, pinhole-free 3D coverage with excellent barrier and dielectric properties.
→ Parylene Solutions
How is Parylene applied?
By chemical vapour deposition (CVD) under vacuum, polymerising directly on surfaces.
→ Parylene Equipment
What thicknesses are typical for Parylene?
Commonly 5–25 µm for electronics; medical/aerospace may require tighter windows.
→ Film Thickness Measurement
How does Parylene compare to liquid coatings?
Superior 3D coverage and barrier; higher cost and specialised equipment vs liquids.
→ Parylene Solutions
What grades of Parylene exist?
N, C, F (and HT variants) balancing dielectric properties, moisture barrier and temperature performance.
→ Parylene Materials
Can Parylene be repaired or reworked?
Yes—laser/plasma/micro-abrasion enable precise local removal for access or repair.
→ Parylene Removal Equipment , Parylene Removal Services
Is Parylene biocompatible?
Certain grades meet medical biocompatibility requirements and are widely used on devices/sensors.
→ Parylene Solutions – Medical
What are the limitations of Parylene?
Higher cost, longer cycle times and more complex masking compared with liquid coatings.
→ Parylene Solutions
What drives Parylene cost?
Dimer consumption, masking effort, load density and vacuum cycle time dominate cost.
→ Parylene Services

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Masking & De-Masking

Why is masking important?
It protects keep-out zones (connectors, test points) ensuring functional interfaces remain coating-free.
→ Masking Solutions
What masking materials are used?
Silicone boots, tapes, dots, gels, liquid masks and custom shapes depending on geometry and process.
→ Masking Consumables
Can masking boots be reused?
Often yes; inspect for wear, swelling or residue to maintain seal integrity and repeatability.
→ Masking Boots
Masking for Parylene vs liquid coatings?
Parylene needs airtight vapour seals; liquids rely on surface barriers and careful tape selection.
→ Masking Solutions
Common masking challenges?
Leakage under tape, adhesive residue, inconsistent coverage—solved via fixtures, boots and process control.
→ Training: Masking
How do you speed up de-masking?
Use pre-formed boots/shapes, optimise takt time, and train operators on efficient removal techniques.
→ Masking Consumables

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Defects & Quality

What are common conformal coating defects?
Bubbles, dewetting, orange peel, bridging, cracking and delamination are frequently encountered.
→ Defects Solutions
What causes dewetting?
Low surface energy or contamination; improve cleaning, surface prep and consider adhesion promoters.
→ Adhesion Promoters
What is orange peel?
A textured finish from viscosity/spray setup/dry-time imbalance; tune solvents, flow and atomisation.
→ Training: Spray Process
What causes bubbles?
Entrapped solvents/moisture or poor application technique; adjust flash times and application parameters.
→ Defects Solutions
What is delamination?
Loss of adhesion due to contamination or stress; address surface prep and primer compatibility.
→ Adhesion Promoters
How do you measure coating thickness?
Coupons/flat areas per IPC guidance, optical methods, or calibrated gauges depending on chemistry/spec.
→ Film Thickness Measurement
What adhesion tests are used?
Cross-hatch tape, pull-off and surface energy checks to validate bond strength and wetting.
→ Training: Adhesion Testing
How do you inspect coatings?
UV inspection with IB100 booths, magnification/AOI and occasional destructive cross-sections.
→ Inspection Booths

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Materials & Chemistry

What coating chemistries are available?
Acrylics, polyurethanes, silicones, epoxies, UV-curables and Parylenes—selected by environment and rework needs.
→ Materials Solutions
How do I choose the right chemistry?
Match hazards (temp, chemicals, condensate) and serviceability; test on coupons when in doubt.
→ Training: Coating Selection
What are adhesion promoters?
Primers (e.g., silanes) that raise surface energy and bonding—vital for Parylene and low-energy substrates.
→ Adhesion Promoters
What are nano coatings?
Ultra-thin hydrophobic/oleophobic layers for splash resistance/easy clean; not a full replacement for conformal protection.
→ Nano Coatings Solutions
Are coatings RoHS/REACH compliant?
Most modern chemistries are; always verify supplier declarations and MSDS for your region.
→ Materials Solutions
Do coatings outgas?
Some do—select low-outgassing materials for aerospace/space and verify with appropriate testing.
→ Aerospace Solutions

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Removal & Rework

Can conformal coating be removed?
Yes—chemical stripping, laser, plasma or micro-abrasion depending on chemistry and tolerance.
→ Coating Removal Services , Coating Removal Equipment
What removal methods exist?
Chemical strippers, abrasion/micro-blasting, plasma and laser ablation—each suits different coatings.
→ Coating Removal Equipment
Can you solder through conformal coating?
Not reliably—locally remove the coating before soldering to ensure a clean metallurgical bond. Use either a wet stripping process in WS100 wet stripping system or an ESD micro blast system like ProBlast 3.
→ Rework & Repair Equipment
How do you strip Parylene?
Plasma, laser, micro-abrasion or targeted chemistries, chosen by area size and precision needed.
→ Parylene Removal Equipment , Parylene Removal Services
When should you rework vs recoat?
Localised defects → rework; widespread issues → strip and recoat for consistent performance.
→ Rework & Repair Services
What equipment removes coatings?
WS100 stripping systems, micro-abrasion blasters and laser workstations are typical platforms.
→ Coating Repair Equipment
Does removal damage the board?
With correct methods and controls, no; incorrect removal risks pad lift or solder-mask damage.
→ Training: Rework

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Equipment & Support

What coating equipment is available?
Dip tanks, spray booths, selective robots, Parylene systems and drying/curing cabinets.
→ Coating Equipment Solutions
Do you provide turnkey solutions?
Yes—integrating equipment, process setup, masking, consumables and operator training.
→ Turnkey Solutions
Do you supply conformal coating consumables?
Yes — we supply masking boots/tapes/dots, adhesion promoters, Parylene dimers and more.
→ Consumables Solutions
Do you provide operator training?
Yes—from fundamentals to advanced troubleshooting, onsite or online.
→ Training Solutions
What support do you offer for equipment?
Installation, validation, spares and ongoing technical consultancy to maintain yield and quality.
→ Support & Service

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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, Parylene grades, masking, inspection, and ProShieldESD integration.
  • 📈 Scalable Solutions – From prototype batches to high-volume production, SCH grows with your needs.
  • 🌍 Global Reach – Responsive support across Europe, North America, and Asia.
  • ✅ Proven Reliability – Built on quality, consistency, and customer satisfaction.

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