Vacuum Coating vs Water Coating: Different Between Vacuum Metalizing and Electroless Plating


Vacuum plating and water plating are two distinct surface treatment technologies used across various industries. They apply different principles and techniques to achieve metal deposition on substrates. This article goes over each method’s definitions, principles, processes, advantages, disadvantages, suitable materials, and applications. Finally, a comparative analysis is presented to highlight their differences, summarized in a table, followed by guidance on choosing the appropriate coating method based on specific needs.

What is Vacuum Plating (Vacuum Metalizing Coating)?

Vacuum coating, also known as vacuum metalizing, involves heating materials for film formation, such as metals or metal oxides, in a vacuum to melt, evaporate, or sublime them, and then depositing the evaporated or sublimated particles (atoms or molecules) onto the surface of a substrate or base material to form a thin film.

Materials for Vacuum Plating





In vacuum plating, it is necessary to evaporate the desired metal components. There are three main methods used to heat and vaporize the metal:

In all cases, the desired metal components are obtained by heating and evaporating the sample to produce metallic gas. The distinguishing feature is that each method uses different amounts of energy and mechanisms, making them suitable for different applications.


What is Water Plating (Electroless Coating)?

Water plating, commonly known as Electroless Plating or water coating. Electroless plating is a process that involves immersing a material in a plating solution without the use of electricity, allowing for a uniform metal coating on materials of any type or shape. Therefore, it is possible to plate non-conductive materials such as plastics and ceramics. Currently, electroless plating is used in a wide range of products, including automotive parts that require lightness and wear resistance, brake components that require precision, and the circuit formation of printed circuit boards and electronic components. It is an important technology that supports modern society.

Metals for Electroless Plating





If electroless plating is defined as a method of plating from an aqueous solution without the use of electricity, it can be divided into two types: displacement plating and chemical reduction plating. Within these, chemical reduction plating is further divided into non-catalytic (such as the silver mirror reaction) and autocatalytic types (such as electroless Ni-P plating):


Differences Between Vacuum Plating and Water Electroless Plating

Vacuum and Water Electroless coating methods differ significantly in their principles, material suitability, properties of the coatings, environmental impacts, applications, and costs. Here’s a detailed comparison:

Vacuum Plating: This method involves evaporating or sublimating a coating material in a vacuum chamber, where the vapor then condenses onto the substrate. Vacuum plating primarily relies on physical processes (physical vapor deposition – PVD) without the need for chemical reactions between the substrate and the deposition material.

Water Electroless Plating: Also known as chemical deposition, this process does not require electricity. Instead, it involves immersing the substrate in a solution containing metal ions, which are chemically reduced and deposited onto the substrate’s surface uniformly, thanks to the presence of a chemical reducing agent.

Vacuum Plating: Suitable for a wide range of materials including metals, glass, ceramics, and some plastics. Its versatility stems from its ability not to require electrical conductivity of the substrate.

Water Electroless Plating: It can be applied to both conductive and non-conductive surfaces, which makes it ideal for plating on a variety of substrates including plastics, glass, and metals. This gives it an advantage in treating objects with complex shapes and sizes.

Vacuum Plating: Produces very thin, uniform, dense, and highly adherent coatings. These coatings are generally more resistant to wear and corrosion because of their high density and purity.

Water Electroless Plating: The coatings are uniform and can cover complex geometries uniformly. However, they may not be as dense as vacuum-plated coatings. The properties of the coating (such as hardness and corrosion resistance) can vary significantly depending on the specific chemicals and process conditions used.

Vacuum Plating: Generally considered more environmentally friendly, as it does not typically involve hazardous chemicals and produces minimal waste. The process is contained, reducing the risk of environmental contamination.

Water Electroless Plating: Involves chemicals that can be hazardous if not managed properly, requiring careful handling and disposal. The process generates waste that must be treated, posing a potential environmental hazard.

Vacuum Plating: Often used in applications requiring high precision and quality of the coating, such as electronics (e.g., semiconductor devices, display panels), automotive parts, and decorative finishes.

Water Electroless Plating: Commonly used for engineering applications where uniform coating thickness and excellent adhesion are required. It is ideal for plating non-conductive materials used in electronics, such as circuit boards, or for applications like aerospace components and medical devices.

Vacuum Plating: Tends to be more expensive due to the high cost of the equipment and the energy required to maintain a vacuum. The initial setup and maintenance costs are significant, making it less cost-effective for small-scale applications.

Water Electroless Plating: Generally more cost-effective, especially for large batches and complex parts. The chemicals used can be expensive, but the overall process cost is usually lower than that of vacuum plating.

FeatureVacuum CoatingWater Electroless Coating
Basic PrincipleUses vacuum conditions to deposit thin films of material onto substrates.Relies on an autocatalytic chemical reaction in an aqueous solution to deposit a coating.
Process EnvironmentOperates in a vacuum chamber at low pressures.Operates at atmospheric pressure in a water-based solution.
Energy RequirementsHigh energy consumption due to the need for vacuum pumps and sometimes high temperatures.Relatively low energy consumption as it usually occurs at room or slightly elevated temperatures.
Material TypesMetals, alloys, ceramics, and some polymers can be deposited.Primarily metals and alloys; limited to materials that can catalyze the chemical reaction.
Thickness ControlHigh precision in thickness control.Less precise, thickness depends on duration of immersion and solution stability.
Application ExamplesMicroelectronics, optical coatings, barrier films, and reflective coatings.Corrosion resistance, electronics (PCB plating), automotive parts.
CostGenerally higher due to complex machinery and maintenance of vacuum systems.Generally lower, simpler setup and operation.
UniformityExcellent uniformity across complex shapes and sizes.Good uniformity, but can be challenging over complex geometries.
AdhesionGood adhesion, but surface preparation is crucial.Excellent adhesion due to chemical bonding at the surface.
Environmental ImpactPotentially high due to energy use and materials used in vacuum generation.Lower impact, uses water-based solutions but chemical disposal must be managed.
Vacuum Metalizing Plating vs Water Electroless Plating

Vacuum Coating vs Water Electroplating Coating, Which One Is Better To Choose?

Choosing between vacuum coating and water plating depends on several factors:

Choosing between vacuum plating and water electroless plating depends on the specific requirements of the application, including the type of substrate, desired properties of the coating, environmental considerations, and cost constraints. Vacuum plating offers superior quality and environmental benefits but at a higher cost, making it suitable for high-value, precision applications. Water electroless plating, on the other hand, provides excellent coverage and adhesion on a variety of materials, including non-conductives, making it ideal for complex industrial components and mass production.