In daily life, the freshly cleaned mobile phone screen is immediately covered with fingerprints, the newly purchased stainless steel faucet is prone to water stains and oil residues, and the lens of glasses is often blurred by grease - these problems all stem from the adsorption of objects' surfaces by fingerprints and oil stains. The emergence of the physical vacuum deposition coating (PVD) anti-fingerprint film technology has achieved "no trace on the fingertip" with an ultra-thin yet highly effective film. Moreover, it also boasts advantages such as wear resistance, corrosion resistance, and environmental friendliness, making it the core technology for surface protection of high-end products. Today, let's together uncover the mystery of PVD anti-fingerprint film and explore how it uses technology to reshape our life experiences.
PVD anti-fingerprint film is a functional film deposited on the substrate surface through physical vacuum coating technology. Its core components include fluorine-containing compounds, diamond-like carbon (DLC), and other low surface energy materials. The thickness is only 50 to 200 nanometers (equivalent to one thousandth of the diameter of a hair strand). Unlike traditional coating-type anti-fingerprint films, it does not simply "coat" the surface but achieves a strong bond between the film layer atoms and the substrate atoms through gas-phase deposition, possessing stronger adhesion and durability. It is a perfect integration of materials science and vacuum technology.
I. The Essence of Fingerprint Residues: Why Are Ordinary Surfaces Prone to Fingerprints?
The "fingerprints" left on our fingertips are a mixture of skin secretions such as oil, sweat, and a small amount of dust. Among them, the oil is the core of the stubborn residue. From a physical and chemical perspective, the key to fingerprint residue is the "difference in surface energy" - the surfaces of common objects (glass, metal, plastic) have higher surface energy, while the fingerprint oil is a low surface energy substance. According to the "like dissolves like" principle, the oil will easily spread and adhere on the high surface energy surface, forming an oil film that is difficult to wipe off.
Furthermore, even seemingly smooth surfaces exhibit nanoscale undulations under a microscope. These "grooves" serve as hiding places for oils, thereby increasing the difficulty of residue removal. The core of PVD anti-fingerprint coating lies in addressing this issue at its root by "reducing surface energy" and "optimizing microstructure".
II. The core principle of PVD anti-fingerprint coating: How to achieve "no trace on fingertips"?
The anti-fingerprint effect of PVD anti-fingerprint film is achieved through the synergy of its low surface energy design and microscopic hydrophobic and oleophobic structures, resulting in a surface characteristic similar to the "lotus leaf effect".
Low surface energy design: Making the grease "unwilling to adhere"
The surface energy of fingerprint oil is approximately 30 to 40 mN/m (millinewtons/meter). The core design of the PVD anti-fingerprint film is to reduce the surface energy of the object to below 25 mN/m. At this point, the low surface energy oil loses its spreading ability and cannot form a uniform oil film. It can only shrink into tiny droplets and can be easily removed by gentle wiping.
To achieve this characteristic, the coating layers mostly use fluorine-containing compounds or diamond-like carbon (DLC) materials. Fluorine is the most electronegative element in nature, and fluorine-containing compounds have stable molecular structures and extremely low surface activity. The DLC coating is composed of sp³ and sp² hybrid carbon atoms, and it inherently has low surface energy. Introducing a small amount of fluorine elements results in even more significant effects.
2. Microscopic hydrophobic and oleophobic structure: Preventing oil from finding a hiding place
The surface of the PVD anti-fingerprint coating is not completely smooth. By adjusting the deposition parameters, nano-scale concave and convex structures ranging from several tens to several hundred nanometers can be formed. These structures allow air to fill the gaps. When oil or water droplets come into contact, what is actually in contact is the "film layer + air" composite structure, which significantly reduces the contact area and enhances the oil and water repellency effect. At this time, the contact angle between water droplets and oil droplets on the surface is greater than 110°, making them less likely to adhere and easier to roll off. Truly achieving "easy cleaning and no residue".
III. Main production process of PVD anti-fingerprint film: "Atomic-level deposition" in a vacuum environment
The performance of PVD anti-fingerprint coating depends on the precision of the preparation process. The mainstream processes are magnetron sputtering and arc ion plating. High-end products may adopt multi-layer composite deposition to adapt to different substrates and scenarios.
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Magnetron sputtering process: The mainstream choice, balancing uniformity and adhesion
Magnetron sputtering is the most commonly used process. Its core is "in a vacuum environment, the magnetic field controls the electron bombardment of the target material to generate atomic-level particle deposition and form a film". It is carried out in four steps: First, vacuum preparation, placing the cleaned substrate into the chamber and evacuating to a high vacuum of 10⁻³ to 10⁻⁴ Pa to reduce air interference; second, introducing argon gas, which is ionized and used as "bombardment particles"; third, target sputtering, the power supply forms a strong electric field, and the magnetic field controls the electrons to bombard the fluorine-containing or metal target, generating a high-energy particle flow; fourth, film deposition, the particle flow is uniformly deposited under the electric field guidance, with the film thickness controlled at 50 to 200 nanometers.
This process has remarkable advantages: the film layer is of high uniformity, capable of covering large areas or curved substrates, with a thickness deviation of no more than ±5%; it has strong adhesion, and no peeling was observed after tests using grid and tape; it has strong compatibility, is suitable for various substrates, and is suitable for mass production.
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Arc Ion Plating Process: A top-notch option that combines fingerprint resistance and high hardness
For products such as the body of mobile phones and the case of watches that need to prevent fingerprints and have high wear resistance at the same time, arc ion plating is often used to prepare DLC anti-fingerprint films. The core principle is that "arc discharge generates high temperature, ionizes the target material into high-energy ions, and deposits into a dense film layer". The target material ionization rate reaches 60% to 80%, and the film layer has higher hardness (HV1500 to 3000). During the preparation process, graphite targets or hydrogen-containing carbon targets are used, and a small amount of fluorine gas can enhance the anti-fingerprint effect. However, the disadvantage is that the equipment cost is high, and subsequent polishing is required to improve the smoothness.
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Composite multi-layer deposition process: Multi-functional synergy
High-end products often adopt multi-layer composite structures, such as "anti-reflective film + wear-resistant ceramic film + fingerprint-resistant fluorocarbon film" for the screen of mobile phones, which combines high light transmittance, scratch resistance and anti-fingerprint properties; "chromium base film + fluorinated chromium functional film" for stainless steel hardware, which enhances adhesion and corrosion resistance. This process requires precise control of the thickness and composition of each layer, and the technical requirements are extremely high.
IV. Core Advantages of PVD Anti-Fingerprint Coating: Why Replace Traditional Technologies?
Traditional spraying and dipping anti-fingerprint coatings have drawbacks such as poor adhesion, easy detachment, and environmental pollution. However, PVD anti-fingerprint coatings have become the mainstream due to their five major advantages:
- Strong adhesion and long service life
- Wear-resistant and corrosion-resistant, providing comprehensive protection
- Environmentally friendly and pollution-free
- Wide applicability and strong compatibility
- High light transmittance without affecting functionality
V. Typical application scenarios of PVD anti-fingerprint film: Penetrating every aspect of life
With its comprehensive performance, the PVD anti-fingerprint coating is widely used in multiple high-end fields:
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Consumer Electronics Industry: Core Applications
This technology is applied to the frame, back cover, camera module, screen of mobile phones, the shell of laptops, smart watches, etc. For instance, high-end mobile phones use PVD anti-fingerprint films to keep the body clean, reduce scratches and enhance the texture.
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Eyewear Industry: Enhancing the Wearing Experience
The anti-fingerprint coating on the lenses reduces the adhesion of grease and enhances the clarity of vision; the anti-fingerprint coating on the metal frames prevents corrosion by sweat and maintains luster, meeting the lightweight demands of people with high myopia.
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Watch Industry: Preserving High-End Quality
The cases of high-end mechanical watches are first coated with decorative films, and then additional anti-fingerprint films are added to balance aesthetics and protection; after coating for diving watches, their resistance to seawater corrosion is enhanced.
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Kitchen and Bathroom Hardware Industry: Easy to Clean and Resistant to Moisture
After being coated, faucets, shower heads, door locks, etc. can automatically shed water stains and oil residues. They are resistant to the corrosion of cleaning agents and remain shiny and clean for a long time. They are the preferred choice for high-end brands such as Kohler and TOTO.
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Automobile and Medical Device Industries
After installing interior buttons of the car, the central control panel, and the window glass coating, the appearance is enhanced and the driving safety is improved; the surgical instruments coated with a film reduce blood adhesion, making disinfection easier; the artificial joints coated with a film enhance biocompatibility and wear resistance.
VI. Technological Trends and Usage Maintenance
The future PVD anti-fingerprint coating will develop in three main directions: Firstly, functional integration, achieving the integration of multiple functions such as "anti-fingerprint, antibacterial, and anti-fog"; Secondly, precise processing, improving the uniformity of the coating layer and reducing production costs; Thirdly, green materials, developing non-fluorine environmentally friendly materials to meet the requirements of sustainable development.
During daily use, it is necessary to avoid sharp objects from scratching, clean gently, stay away from high-temperature environments, and wipe regularly in order to extend the lifespan of the film layer.
Conclusion: The Technological Power in Microscopic Films
From the screen of a mobile phone to the hardware of the kitchen and bathroom, the PVD anti-fingerprint film, with its nanometer-level film, changes the living experience. Behind this is the integration and innovation of multiple disciplines. With technological iterations, it will achieve more functional integration and have a wider range of applications, making "no trace on fingertips and no worries about cleaning" a common occurrence, highlighting the core value of technology serving life - enhancing the happiness and convenience of life in the minutiae.
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