ALOx PET Film

AlOx (Aluminum Oxide) coating involves depositing a thin aluminum oxide layer onto a substrate, typically a polymer film such as PET (Polyethylene Terephthalate).

This coating enhances the film’s barrier properties, making it more resistant to gas, moisture, and light transmission, which is crucial for packaging applications.

The AlOx coating process is usually carried out using a technique called Physical Vapor Deposition (PVD), the most common of which is Reactive Sputtering.

Here’s an overview of the process:

1. Substrate Preparation: The PET film or other substrate is cleaned and prepared to ensure a smooth surface for coating. This may involve treating the film to improve adhesion.
2. Vacuum Chamber: The substrate is placed in a vacuum chamber, which is then evacuated to create a low-pressure environment. This is necessary to prevent contamination and ensure uniform deposition of the coating.
3. Sputtering Target: An aluminum target, typically a pure aluminum metal piece, is used to source the aluminum atoms that will form the coating.
4. Reactive Sputtering: A controlled flow of oxygen gas is introduced in the vacuum chamber. An electric field is applied to create a plasma around the aluminum target. The energetic ions in the plasma collide with the aluminum target, ejecting aluminum atoms.
5. Aluminum Oxide Formation: As the ejected aluminum atoms travel through the oxygen gas, they react with the oxygen to form aluminum oxide (Al2O3). These aluminum oxide molecules then deposit onto the surface of the substrate, forming a thin, transparent coating.
6. Coating Thickness: The thickness of the AlOx coating can be controlled by adjusting the sputtering parameters, such as the power, pressure, and deposition time. The thickness typically ranges from a few nanometers to tens of nanometers.
7. Post-Processing: After the coating process, the coated film may undergo additional treatments, such as curing or heat treatment, to enhance its properties and ensure the stability of the coating.

The AlOx-coated film provides excellent barrier properties against oxygen, water vapor, and other gases, making it suitable for sensitive applications such as food packaging, pharmaceuticals, and electronics. It is also transparent, allowing clear visibility of the contents, an advantage over other barrier films like metallized films.