Vacuum coating machines in the decorative field often employ vacuum evaporation coating. Vacuum evaporation is a process where the material to be coated is placed in a vacuum and evaporated or sublimated, depositing it onto the surface of a workpiece or substrate. It involves heating the raw material in an evaporation container within a vacuum chamber, causing its atoms or molecules to vaporize and escape from the surface, forming vapor that flows onto a solid surface (called a substrate) and condenses to form a solid film. The shape of the evaporation source can be customized based on the properties of the evaporation material and its wettability, using different forms and different evaporation source materials. Vacuum evaporation coating consists of three layers: a primer layer (6~12µm) + a coating layer (1~2µm) + a topcoat layer (10µm). Pre-assembly treatment involves wiping the substrate surface clean of impurities and dust to improve spray yield. The substrate is then mounted on a special fixture to secure it on the production line, achieving the desired appearance and function according to design requirements.
Another part uses vacuum sputtering, which usually refers to magnetron sputtering, a high-speed, low-temperature sputtering method. An inert gas (Ar) is filled into a vacuum, and a high-voltage direct current is applied between the cavity and the metal target (cathode). Electrons generated by glow discharge excite the inert gas to produce argon positive ions. These positive ions move at high speed towards the cathode target, ejecting target atoms and depositing them onto the plastic substrate to form a thin film.
Vacuum sputtering machines use high-energy particles (usually positive ions accelerated by an electric field) to bombard a solid surface. The phenomenon where atoms and molecules on the solid surface exchange kinetic energy with the incident high-energy particles and are then ejected from the solid surface is called sputtering. The sputtered atoms (or atomic groups) possess a certain amount of energy, and they can redeposit and condense on the solid substrate surface to form a thin film. Vacuum sputtering requires filling an inert gas in a vacuum state to achieve glow discharge. This process requires a vacuum level in a molecular flow state. Vacuum sputtering can also be performed directly without a primer, depending on the characteristics of the substrate and target material. The coating layer of vacuum sputtering can be built up by adjusting the current and time, but it cannot be too thick, generally ranging from 0.2 to 2 μm.
