Choose the Right Coating for Your Application
Conformal coating selection depends on operating environment, temperature range, rework requirements, and cost. Kingdta's engineering team helps select the optimal coating material for your application.
| Coating Type | Temp. Range | Key Properties | Applications |
|---|---|---|---|
| Acrylic (AR) | -65°C to +125°C | Easy rework, good moisture resistance, low cost | Consumer, industrial, general purpose |
| Silicone (SR) | -65°C to +200°C | Excellent high-temp, flexible, vibration resistant | Automotive, aerospace, high-temp industrial |
| Polyurethane (UR) | -40°C to +125°C | Chemical resistance, abrasion resistance | Outdoor, chemical exposure environments |
| Epoxy (ER) | -65°C to +150°C | Excellent adhesion, hard coating, chemical resistant | Harsh chemical environments, potting |
Application Methods
Selective Spray Coating
Robotic selective spray applies coating precisely to defined areas, masking connectors, test points, and heat-dissipating components automatically.
Dip Coating
Full-board dip coating for maximum coverage. Connectors and test points are masked before dipping.
Brush Coating
Manual brush application for small areas, touch-up, and rework. Used for prototype and low-volume orders.
Quality Verification
- UV fluorescence inspection — coating coverage verified under UV light
- Coating thickness measurement per IPC-CC-830
- Adhesion testing per ASTM D3359
- Dielectric withstand testing after coating
- Visual inspection per IPC-A-610
Conformal Coating for a Marine VHF Radio Controller in Salt Spray Environment
A Danish marine electronics company manufacturing a VHF radio controller for commercial fishing vessels — requiring IEC 60945 salt spray and humidity resistance certification for the assembled PCB.
The Problem
The customer's previous conformal coating supplier was applying acrylic coating by dip, resulting in uneven coverage and coating contamination of connector contacts. During IEC 60945 salt spray testing, 3 of 10 boards failed due to corrosion at inadequately coated solder joints. The connector contamination also caused intermittent contact failures in the field.
Key Challenges
- IEC 60945 salt spray test: 48 hours at 5% NaCl, 35°C — zero corrosion on solder joints
- 12 connector positions and 24 test points must remain uncoated for electrical contact
- Dip coating process causing uneven coverage — thin spots at solder joint fillets
- Connector contact contamination causing intermittent field failures
- Polyurethane coating required for better chemical resistance in marine environment
Our Solution
We switched from dip coating to selective spray coating using a Nordson Select automated coating machine with a programmable X-Y-Z spray head. The coating program precisely masks all 12 connector positions and 24 test points using software-defined exclusion zones. We use Humiseal 1A33 polyurethane coating applied in two passes to achieve a consistent 50–75μm dry film thickness across all solder joints. Coating thickness is verified by cross-section measurement on a sample board from each production lot. All boards are inspected under UV light to verify complete coverage.
Results & Outcomes
"The selective spray coating process Kingdta implemented solved both our IEC 60945 compliance problem and our connector contamination issue in one step. The UV inspection images they provide with each lot give us confidence that coverage is complete. We've had zero coating-related failures in 2 years of field deployment."
Quality Engineer, Marine Electronics Company — Copenhagen, Denmark