When it comes to protecting sensitive electronics and critical components, the best solutions are often the ones you can’t see. Parylene coating is exactly that — an ultra-thin, transparent film that provides superior protection without adding weight, altering dimensions, or affecting performance.
In this article, we break down what Parylene is, how the process works, and why it delivers results you can trust but barely see.
What is Parylene?
Parylene is a family of polymer coatings applied using a unique vapour deposition process. Unlike liquid coatings, it doesn’t rely on solvents or curing. Instead, it forms a pinhole-free, conformal layer that follows every contour of the surface — even sharp edges, crevices, and internal cavities.
Key Characteristics:
- Completely transparent and ultra-thin (typically 5–50 µm)
- Solvent-free, vacuum-deposited protective film
- Uniform coating with no pooling or bridging
- Excellent barrier to moisture, chemicals, and gases
- High dielectric strength and electrical insulation
How is Parylene Applied? The Vapour Deposition Process
Parylene coating isn’t sprayed or dipped — it’s deposited molecule by molecule in a vacuum chamber. Here’s how:
- Vaporisation – Solid Parylene dimer is heated under vacuum, turning it into a vapour.
- Pyrolysis – The vapour is heated again to break the dimer into monomers.
- Deposition – These monomers enter a cool coating chamber where they polymerise and form a thin, uniform film over all exposed surfaces.
- No Cure Required – Unlike liquid coatings, Parylene is ready immediately — no oven curing, no drying time.
This unique process ensures 360° coverage, reaching areas where sprays, brushes, and dips simply can’t.
Why Use Parylene? Visible Results from an Invisible Layer
Although invisible to the eye, Parylene’s protective performance delivers very real benefits:
| Benefit | What It Means |
| Moisture & Chemical Barrier | Protects against corrosion, solvents, humidity, body fluids and harsh environments |
| Electrical Insulation | High dielectric strength and low leakage — ideal for PCBs, medical devices, sensors |
| Ultra-Thin & Lightweight | Adds protection without affecting size, weight or functionality |
| Biocompatible & ISO 10993 Certified | Safe for medical, implantable and life-science applications |
| Long-Term Reliability | No cracking, peeling, or yellowing — even under stress or thermal cycling |
Where Is Parylene Used?
Parylene’s versatility makes it suitable across industries where reliability is critical:
- Aerospace & Defence — avionics, satellites, fuel systems, sensors
- Medical Devices — catheters, implants, hearing aids, surgical tools
- Automotive & EV — PCBs, battery systems, ADAS components
- Consumer Electronics — wearables, sensors, microcircuits
- Industrial & Energy — sensors, control systems, harsh environment electronics
Parylene vs Traditional Liquid Conformal Coatings
| Feature | Parylene | Conformal Coatings (Acrylic, Silicone, Urethane) |
| Application | Vacuum deposition | Brush, spray, dip |
| Coverage | Complete 3D coverage, no shadows | Limited by line-of-sight application |
| Thickness | 5–50 µm highly uniform | Often uneven, 25–200 µm |
| Solvents | Solvent-free | May contain VOCs |
| Cure Time | No cure required | Minutes to hours |
| Adhesion | Requires pre-clean and adhesion promoter | Generally good without promoter |
| Cost | Higher per unit — but minimal rework and failures | Lower upfront cost but more defects/rework |
Is Parylene Right for Your Product?
Parylene is ideal when:
- You need high reliability in extreme environments
- Conventional coatings don’t reach complex geometries
- Devices are miniaturised or lightweight
- Biocompatibility and cleanliness are required
- Long-term product life and consistency are critical
Conclusion
Parylene may be invisible, but the results are not. With unmatched uniformity, protection and long-term performance, it delivers reliability where failure is simply not an option.
Whether you’re designing next-generation electronics, life-saving medical devices, or mission-critical aerospace systems — Parylene ensures invisible protection with visible results.
