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Coating method of UV vacuum plating

Release time:

2026-05-28 07:17

In the coating stage of UV vacuum plating, two primary methods are employed: thermal evaporation and magnetron sputtering. These techniques form a metallic thin film on the primer surface, serving as the core step for achieving a metallic luster. Following coating, a UV‑curable topcoat is applied to protect and decorate the metal layer. Each method differs in equipment design, operating principles, coating quality, and application areas, and all are closely linked to the subsequent UV curing process. Understanding the distinctions between these coating approaches enables the selection of an appropriate process route based on product requirements.

I. Thermal Evaporation Coating Method

Thermal evaporation coating is a deposition technique in which metal materials are heated to vaporize; the metal vapor then diffuses and deposits onto the substrate surface in a vacuum environment, forming a metallic thin film.

1. Basic Principle

Thermal evaporation coating is carried out in a vacuum deposition chamber. The substrate to be coated is placed on a holder inside the chamber, while the metallic coating material is positioned in a heating source. Once the required vacuum level is achieved, the heating system is activated, raising the temperature of the metal material to its evaporation point. As the metal vaporizes, its atoms or molecules travel in straight lines through the vacuum and condense onto the cooler substrate surface, forming a thin metallic film. After coating is complete, the substrate is removed for UV topcoat application and subsequent UV curing.

2. Heating Method

The heating methods used in thermal evaporation coating primarily include resistive heating and electron-beam heating. Resistive heating involves passing an electric current through a metal wire or a metal boat to heat the metal material placed inside, causing it to evaporate. This approach is simple and cost‑effective, making it suitable for low‑melting‑point metals such as aluminum. Electron-beam heating, on the other hand, uses a high‑energy electron beam to bombard the metal material, generating localized high temperatures that induce evaporation. This method is well suited for high‑melting‑point metals but entails higher equipment costs.

3. Impact on Subsequent UV Processes

The metal thin film formed by thermal evaporation coating exhibits a relatively smooth surface, which facilitates uniform application and leveling of the UV topcoat. Given the moderate adhesion of the coating layer, a UV primer is required to provide an effective substrate; the formulation design and curing quality of the primer significantly influence the overall adhesion.

II. Magnetron Sputtering Coating Method

Magnetron sputtering is a coating technique that uses ions generated by glow discharge to bombard a target material, causing atoms from the target to be sputtered off and deposited onto the workpiece, thereby forming a metallic thin film.

1. Basic Principle

Magnetron sputtering is performed in a vacuum deposition chamber. A high-voltage electric field is applied between the target (the coating material) and the workpiece, while a magnetic field is configured on the back side of the target. After introducing a small amount of an inert gas—typically argon—the gas molecules are ionized, forming a plasma. Under the influence of the electric field, positive ions in the plasma are accelerated to bombard the target surface, causing atoms from the target to be sputtered off and deposited onto the workpiece, thereby forming a thin film. Once the coating process is complete, the workpiece is removed for UV topcoat application and subsequent photopolymerization.

2. Impact on Subsequent UV Processes

The metal thin film formed by magnetron sputtering exhibits high surface energy, resulting in superior wettability and adhesion to UV topcoats. The coating is dense and uniform, providing an excellent adhesive substrate for the UV topcoat and enhancing the overall durability of the coating. For automotive components and other products requiring high adhesion, the combination of magnetron sputtering and a UV topcoat offers distinct advantages.

III. Comparison of Two Methods in UV Vacuum Plating

The differences between thermal evaporation coating and magnetron sputtering coating in UV vacuum plating processes are manifested in several aspects.

1. In terms of equipment costs, thermal evaporation coating systems are relatively inexpensive, making them well-suited for companies with limited budgets; in contrast, magnetron sputtering systems require a higher capital investment and are ideal for applications that demand superior coating quality.

2. In terms of coating quality, thermal evaporation coatings exhibit moderate adhesion and average compatibility with UV topcoats; by contrast, magnetron sputtering coatings offer strong adhesion and a more robust bond with UV topcoats.

3. In terms of compatibility with UV coating processes, thermal evaporation deposition yields a smoother surface finish and facilitates easy leveling of the UV topcoat; by contrast, magnetron sputtering deposition provides a higher surface energy, resulting in superior wetting of the UV topcoat and enhanced interlayer adhesion.

4. In terms of material compatibility, thermal evaporation is suitable for low-melting-point metals such as aluminum, but the coating still requires a UV‑curable topcoat for protection; magnetron sputtering is applicable to a wide range of metals and alloys, producing a denser coating that, when combined with a UV‑curable topcoat, delivers superior overall durability.

IV. Integrated Coordination Between Coating Methods and UV Curing Processes

Regardless of the coating method employed, UV curing is a critical step for subsequent protective and decorative finishing. After coating, the workpiece must be sprayed with a UV‑curable topcoat and subjected to UV irradiation to cure it. Under UV exposure, the topcoat undergoes crosslinking within seconds, forming a highly durable, abrasion‑resistant protective layer.

The two coating methods directly affect the adhesion of UV topcoats. Because magnetron sputtering produces a dense film with high surface energy, its UV topcoat adhesion is generally superior to that of thermal evaporation coatings. In applications requiring high durability, magnetron sputtering paired with a high-performance UV topcoat represents a more reliable combination.

V. Conclusion

UV vacuum plating primarily employs two coating methods: thermal evaporation and magnetron sputtering. Thermal evaporation is characterized by lower equipment costs and simple operation, making it well suited for depositing low-melting-point metals such as aluminum; when combined with a UV topcoat, it is widely used in cosmetic packaging, toy decoration, and other applications. Magnetron sputtering produces dense coatings with strong adhesion and excellent uniformity, ensuring a more robust bond with UV topcoats; however, it requires higher capital investment and is ideal for applications—such as automotive components and optical devices—that demand superior coating quality. Each method has distinct advantages in terms of equipment cost, coating quality, and compatibility with UV processes, so the choice should be based on a comprehensive assessment of product requirements, budget constraints, and subsequent UV coating needs.

Disclaimer: The above content has been compiled from publicly available sources and is provided for reference only. If any infringement occurs, please contact us, and we will address it promptly.

Bosheng Related Product Recommendations – Vacuum Plating
Primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, containing 20% TPGDA.
B-151	Modified epoxy acrylate	Low halogen, yellowing-resistant, excellent plating performance, and strong adhesion.
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-212A	Aromatic polyurethane acrylate	High cost-performance, excellent plating adhesion, good toughness, and resistant to boiling water.
B-221	Aliphatic polyurethane acrylate	Fast curing, resistant to boiling water
B-268M	Aliphatic polyurethane acrylate	Good flexibility, excellent adhesion, superior plating performance, and strong hiding power.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV.
B-619W	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, wear resistance, and chemical resistance.
Intermediate coat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-374	Aliphatic polyurethane acrylate	Good flexibility, excellent leveling, resistant to abrasion and chemicals, and resistant to yellowing.
B-601	Aromatic polyurethane acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost-effectiveness.
B-6020	Special functional group acrylate	Resistant to boiling water, excellent color development, and strong interlayer adhesion.
Topcoat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-221	Aliphatic polyurethane acrylate	Fast curing, resistant to boiling water
B-301	Aromatic polyurethane acrylate	Fast curing, excellent toughness, and good sandability.
B-302	Aromatic polyurethane acrylate	Fast curing, high strength, excellent toughness, and good grindability.
B-368	Aliphatic polyurethane acrylate	Good toughness, excellent leveling, excellent bend resistance, and excellent heat resistance.
B-374	Aliphatic polyurethane acrylate	Good flexibility, excellent leveling, resistant to abrasion and chemicals, and resistant to yellowing.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV.
B-601	Aromatic polyurethane acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost-effectiveness.
B-6016C	Special functional group acrylate	Easy to apply, resistant to yellowing and boiling water, and improves the appearance of the paint film.
B-6019	Special functional group acrylate	Good leveling, excellent wetting, resistant to boiling water, and excellent color dispersion.
B-609	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch resistance, and chemical resistance.
B-615A	Aliphatic polyurethane acrylate	Fast curing, excellent toughness, wear resistance, and chemical resistance.
B-619W	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, wear resistance, and chemical resistance.
B-6210	Aliphatic polyurethane acrylate	Low viscosity, chemical resistance, environmental resistance, and dual photothermal curing.
B-6211	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch-resistant, and free of organotin.
B-919B	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, and outstanding chemical and wear resistance.
Monomer Recommendation
Product Model/English Abbreviation	Product Name/Product Type	Product Features
BM2223 (TPGDA)	Dipropylene glycol diacrylate	Good flexibility and low volatility
BM3231 (TMPTA)	Trimethylolpropane triacrylate	High crosslink density, high hardness, high gloss, and excellent wear resistance.
BM3235 (PET3A)	Pentaerythritol triacrylate	Fast curing, high crosslink density, high hardness, and chemical resistance.
BM3380 (3EO-TMPTA)	Pentaerythritol triacrylate	More flexible and less irritating than TMPTA.
BM6261 (DPHA-80)	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.
BM6263 (DPHA-90)	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.

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