Choosing the wrong conformal coating type leads to field failures, expensive rework, and voided warranties. The three most commonly debated types are acrylic, silicone, and urethane. This guide delivers a clear, honest comparison — and explains why acrylic coatings like Acrylcoat from CONINS Pune are the preferred choice for 90% of industrial and commercial PCB applications.
Full Comparison at a Glance
| Property | Acrylic (AR) | Silicone (SR) | Urethane (UR) | Epoxy (ER) |
|---|---|---|---|---|
| Rework Ease | ✔ Easy (solvent) | ✘ Very difficult | ⚠ Moderate | ✘ Near impossible |
| Moisture Protection | ✔ Good | ✔✔ Best | ✔ Good | ✔✔ Excellent |
| Chemical Resistance | ⚠ Moderate | ⚠ Moderate | ✔ High | ✔✔ Very High |
| Max Working Temp | 120°C | 200°C | 130°C | 150°C |
| Drying / Cure Speed | ✔ Fast (60 min @80°C) | ⚠ Slow | ⚠ Moderate | ✘ Slow |
| Cost per Litre | ✔ Lowest | ✘ High (2–3×) | ⚠ Medium | ⚠ Medium |
| UV Fluorescence (inspection) | ✔ Yes | ⚠ Some grades | ✔ Yes | ✘ No |
| Fungal Resistance | ✔ Good | ✔ Excellent | ✔ Good | ✔ Good |
| Market Share | ~70% | ~15% | ~10% | ~5% |
Acrylic Conformal Coating (AR Type) — The Industry Standard
Acrylic coatings — also called AR lacquer, acrylic PCB varnish, circuit board acrylic coat or simply PCB lacquer — dominate global conformal coating usage. All CONINS Acrylcoat products (AR-30, ALQ-30, ALQ-60, ALQ-100, SKR-70, LED-LGT-SPL-60) are acrylic-based.
- ⚡ Fast drying — oven cure at 80°C for 60 minutes; touch-dry within minutes at room temperature
- 🔧 Easy rework — dissolves cleanly with Elclean Thinner AR — no destructive processes
- 🔌 High dielectric strength — Acrylcoat SKR-70 achieves 25 kV/mm
- 🌿 Ozone-friendly — eco-safe RoHS-aligned formulations
- 💰 Best cost/protection ratio — lowest cost per litre for volume production
- 🔬 UV fluorescent — easy quality inspection under UV lamp
- 🏭 Wide substrate compatibility — FR4, ceramic, MCPCB, plastic, metal
✅
Recommended for: Consumer electronics, LED lighting, automotive electronics (SKR-70), industrial controls, telecom equipment, EV battery management systems, IoT devices, and virtually all commercial PCB production.
Silicone Conformal Coating (SR Type) — When Extreme Heat Applies
Silicone is the right choice only when continuous operating temperature exceeds 150°C — aerospace engine sensors, exhaust manifold electronics, or high-power LED junction areas.
- ✅ Operates from −65°C to +200°C continuously
- ✅ Best-in-class moisture and humidity resistance
- ❌ Extremely difficult to rework — bonds tenaciously to all surfaces
- ❌ Highest cost — 2–3× more expensive than acrylic
- ❌ Slow cure — often requires UV or specialised heat cure
- ❌ Poor adhesion promoter compatibility — requires specific primers
⚠️ Caution: Once silicone coating is applied, component replacement becomes very costly. Only select silicone if your application genuinely demands above-150°C continuous operation.
Urethane / Polyurethane Coating (UR Type) — Chemical Resistance Focus
Urethane coatings shine when PCBs face direct exposure to fuels, oils, hydraulic fluids or aggressive industrial solvents — marine engine electronics, agricultural machinery, industrial pump controls.
- ✅ Superior chemical and solvent resistance vs acrylic
- ✅ Good abrasion and mechanical strength
- ⚠️ Moderate rework — requires specialised solvents, more labour
- ⚠️ Medium cost — more than acrylic, less than silicone
CONINS Product Recommendation by Application
| Your Application | Best CONINS Product | Why |
|---|---|---|
| General PCB production | Acrylcoat AR-30 | All-round protection, easy rework |
| Dense SMT, fine-pitch components | Acrylcoat ALQ-30 | Lower viscosity, flows between components |
| LED lighting products | LED-LGT-SPL-60 | Designed for LED thermal & optical needs |
| Automotive ECUs, ABS, ADAS | Acrylcoat SKR-70 | 25 kV/mm, CTI 600, 120°C rated |
| Tropical climates (Vietnam, India) | G1/G2/G3 Compliance | Tested to 93% RH IEC 60068 |
| Maximum moisture — outdoor | Acrylcoat ALQ-100 | Highest viscosity = thickest protection |
| IP protection / anti-copy | Opaque Black Coating | Hides PCB design completely |
Frequently Asked Questions
What is the main difference between acrylic and silicone conformal coating? ▼
Acrylic coatings are easier to rework with solvents, dry faster and cost significantly less. Silicone coatings operate at extreme temperatures (up to 200°C) and offer superior moisture resistance, but are very difficult to rework and 2–3× more expensive. For most electronics applications, acrylic provides the best balance of protection and practicality.
Which conformal coating is easiest to rework? ▼
Acrylic conformal coatings (AR type) are the easiest to rework — they dissolve readily in solvents like Elclean Thinner AR from CONINS Pune. Component replacement and re-coating is straightforward, making them the preferred choice for any production environment where repairs may be needed.
Is acrylic conformal coating suitable for automotive electronics? ▼
Yes. CONINS Acrylcoat SKR-70 is specifically formulated for automotive PCBs, achieving 25 kV/mm dielectric strength and CTI 600, rated for 120°C continuous operation. It meets the performance demands of ECUs, ABS modules, and automotive LED drivers.
What conformal coating works best in Vietnam's tropical humidity? ▼
For Vietnam's 80–95% RH tropical climate, CONINS G1/G2/G3 Compliance Coating or Acrylcoat ALQ-100 are recommended. Both are tested to IEC 60068 damp heat and mold resistance standards, providing reliable protection in monsoon-season conditions.
Can I apply acrylic coating over silicone components? ▼
Acrylic coatings can have poor adhesion directly over silicone potting compounds or silicone gaskets. Where silicone components are present, masking those areas before coating is recommended. Contact CONINS technical team for specific application advice: response@pcbconformalcoating.net.