Introduction
With the widespread use of touchscreens, there are higher demands for the surface performance of glass. Fingerprints and oil stains not only make screens look dirty but also affect visual clarity. How can we keep glass surfaces clean and free of fingerprints and oil? Today, we explore a surface treatment technology: AF coating
How AF Coating Works on glass
AF (Anti-Fingerprint) coating, also called APF coating, oleophobic coating or hydrophobic coating, works by creating an energy barrier. Fluorinated polymers are applied to the glass surface at a nanoscale precision, forming a dense film just 50-200 nanometers thick.
This reduces the surface energy of the glass from 72 mN/m (ordinary glass) to an ultra-low 15-20 mN/m. The energy barrier increases the liquid contact angle beyond critical thresholds of 110° (water-repellent) and 90° (oil-repellent), mimicking the “lotus effect” to repel water, oil, and fingerprints.
Key Properties of AF Coating Glass
Modern AF coatings offer multi-dimensional performance:
Water repellency | Contact angle of 110-120°, outperforming traditional materials |
Friction coefficient | 0.05-0.1 (comparable to PTFE) |
Light transmission | >92% (at 550nm wavelength) |
Wear resistance | Survives 10,000 steel wool abrasion tests (1Kgf load) |
Chemical stability | Resists solutions with pH 3-11 |
| Temperature tolerance | Stable performance from -40℃ to 200℃ |
These properties ensure reliability even in harsh conditions. For example, a smartwatch brand tested its AF-coated screen after 1,000 hours of seawater exposure—it retained 95% of its water-repellent function.
AF Coating Production Methods
1:Vacuum Deposition
Process In a vacuum chamber (10⁻³~10⁻⁵ Pa), fluorinated materials are vaporized and deposited onto glass:
- Physical Vapor Deposition (PVD): Magnetron sputtering targets (e.g., magnesium fluoride) release fluorine atoms under ion bombardment.
- Chemical Vapor Deposition (CVD/PECVD): Fluorinated gases (e.g., C₄F₈) decompose and deposit via plasma activation.
Features
Aspect | Details |
Coating quality | Nanoscale uniformity (±2nm), non-porous |
Adhesion | Molecular bonding, passes 5B cross-cut test |
Efficiency | Roll-to-roll speed: 3m/min; 30s per smartphone glass |
Cost | High equipment investment (~3M/line),but3M/line),but0.2 per unit |
Limitations | Uneven coverage on complex curves; requires custom fixtures |
Applications | Smartphone/tablet screens, camera lenses |
2:Spray Coating
Process
Fluorinated coatings (e.g., modified PTFE) are atomized via high-pressure nozzles:
- Supersonic spraying: Compressed air accelerates to 400m/s, coating particles <10μm.
- Electrostatic assist: Substrate charged to 5-10kV improves adhesion.
- Curing: Multi-stage drying (80-150℃) forms cross-linked networks.
Features
Aspect | Details |
Adaptability | Works on any shape (e.g., curved car dashboards) |
Thickness | 1-5μm controllable; roughness Ra<0.1μm |
Cost | Equipment: $500k; 60% less energy than vacuum methods |
Drawbacks | “Coffee ring” edges require trimming |
Sustainability | VOC emissions need treatment; water-based versions in development |
| Applications | Car touchscreens, appliance panels, architectural glass |
Applications of AF Glass
AF glass is widely used in:
- High-end devices: Camera lenses, medical displays
- Frequently touched devices: Smartphones, tablets, laptops
- Harsh environments: Industrial control panels, outdoor screens
As AF coating technology matures and costs drop, its applications continue to expand.
How AF Coating Enhances AR/AG Glass
Standard AR (Anti-Reflective) and AG (Anti-Glare) coatings lack fingerprint resistance. Over time, oils, dirt, and chemicals degrade these coatings, causing peeling. Adding an AF layer improves the durability and lifespan of AR/AG coatings.
Glass Type | Weakness | AF Coating Benefit | Result |
AR Glass | Reflective layers degrade | Protects against oil/abrasion | 3x longer lifespan |
| AG Glass | Matte surfaces trap oils | Reduces friction | 40% smoother touch |
FAQs
Q: Does AF coating completely prevent fingerprints and oil stains?
A: AF coating significantly reduces but doesn’t fully eliminate them.
Q: How long does AF coating last?
A: Depends on usage frequency and environment—harsh conditions may shorten its lifespan.
Q: Does AF coating affect screen clarity?
A: No. Its anti fingerprinting and self-cleaning properties actually help maintain glass transparency and clarity