Industrial automation computers are frequently installed in environments with aggressive atmospheric contaminants. Coastal ports, offshore drilling platforms, wastewater treatment plants, and paper mills subject electronics to humid air laden with salt chlorides, hydrogen sulfide ($H_2S$), and acidic condensates.
When airborne moisture lands on an uncoated circuit board, microscopic dendritic metal whiskers grow between closely spaced surface-mount component traces. These conductive dendrites create intermittent electrical shorts, drop communication lines, and cause permanent motherboard failure.
Protecting internal electronics against atmospheric corrosion requires applying Industrial Conformal Coating.
Conformal Coating Chemistry Comparison
| Coating Chemistry | Dielectric Strength | Moisture / Humidity Barrier | Chemical & Solvent Resistance | Operating Temp Range | Rework / Repair Feasibility |
| Acrylic Resin (AR) | High ($300\text{ V/mil}$) | Excellent | Moderate (dissolves in common solvents) | $-40^\circ\text{C}$ to $125^\circ\text{C}$ | Easy; stripped with mild solvent for soldering |
| Silicone Resin (SR) | Very High ($450\text{ V/mil}$) | Superior | High (resists industrial chemicals) | $-65^\circ\text{C}$ to $200^\circ\text{C}$ | Difficult; requires mechanical scraping/abrasion |
| Polyurethane (UR) | High ($350\text{ V/mil}$) | Superior | Extreme (resists acids, fuel, solvents) | $-40^\circ\text{C}$ to $130^\circ\text{C}$ | Very Difficult; requires thermal stripping |
| Parylene (XY) | Ultra-High ($5000\text{ V/mil}$) | Absolute | Impervious to nearly all chemical exposure | $-200^\circ\text{C}$ to $150^\circ\text{C}$ | Specialized cleanroom chamber process only |
The Micro-Mechanics of Airborne PCB Corrosion
In unconditioned industrial facilities:
- Relative humidity regularly exceeds 85%. Combined with ambient sulfur or chloride salts, moisture forms an electrolytic solution on the PCB surface.
- Under DC operating bias (such as 3.3V or 5V logic lines), copper and tin ions migrate across the board laminate, forming conductive bridges (dendrites) between adjacent pins of fine-pitch QFP or BGA chips.
- Applying an automated, uniform $25\,\mu\text{m}$ to $75\,\mu\text{m}$ layer of conformal coating creates a continuous protective barrier that seals copper traces, solder joints, and component leads from ambient moisture.
- Heavy-duty platforms like the 15.6″ Full IP65 Waterproof Android Industrial Panel PC combine sealed fanless enclosures with conformally coated internal motherboards to provide dual-layer environmental protection in damp processing halls.
Visual Inspection and Maintenance Procedures (IPC-A-610 Standards)
During scheduled equipment overhauls, maintenance technicians can inspect conformal coating integrity:
- Blacklight (UV) Inspection: Industrial conformal coatings incorporate a fluorescent UV tracer dye. Illuminating the circuit board with an ultraviolet blacklight ($365\text{ nm}$) causes the coating to fluoresce brightly under inspection.
- Identifying Defect Areas: Look for non-fluorescent dark voids (indicating dewetting or insufficient coating thickness), bubbles bridging fine-pitch IC pins, or cracking along component edges caused by thermal shock.
- Local Field Rework: When replacing a failed component on an acrylic-coated board:
- Dissolve the localized coating using a cotton swab moistened with a mild stripping solvent.
- Desolder and replace the surface-mount component.
- Clean the area with 99% isopropyl alcohol, dry thoroughly, and apply a fresh layer of acrylic conformal coating using a fine applicator brush, ensuring overlap with the original coating.
Enhancing Field Longevity in Coastal Facilities
For installations exposed to marine salt spray or industrial sulfur, specifying conformal coating protects internal electronics from airborne corrosion. Enclosing coated motherboards within die-cast aluminum housings—as implemented in the 12.1″ Die-Cast Aluminum Snap-in Clip Touch Panel PC —ensures multi-tiered resistance to moisture and vibration.
Summary
Specifying automated conformal coating on industrial computers extends hardware MTBF in humid, coastal, and chemical environments, preventing dendritic growth and short circuits across years of operation.
Sourcing coated computing platforms or requesting salt-spray test certifications (ASTM B117)? Contact INNODA’s manufacturing engineering department for technical datasheets and qualification reports.