Electroplating Guide: Process, Materials & When To Use

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Electroplating is a process that uses electrolysis to deposit metals or alloys onto the surface of a workpiece, creating a uniform, dense and well-bonded metal layer. It is mainly used to improve the hardness, wear resistance and corrosion resistance of workpieces, or to enhance their appearance.

In reality, however, it has been found that even when using the same electroplating process, the results can vary significantly depending on the material used. Some materials can exhibit issues such as peeling, blistering and poor adhesion after plating.

This article serves as a practical plating guide, explaining the principles of electroplating and identifying suitable materials and surface finishing methods to help you select the right materials for your needs.

What Is Electroplating?

The process of electrodeposition, also known as electroplating, is a type of electrochemical process in which a thin layer of a particular metal is applied to a suitable base through the passage of an electric current. In the process, the anode consists of a material that dissolves, releasing metal ions into the electrolyte and maintaining the bath’s chemical composition, while releasing electrons to the circuit. At the cathode(parts need electroplating), metal ions from the electrolyte are reduced and then deposited as a thin, uniform layer for the protection or enhancement of the object.

Step-by-Step Electroplating Process for Metals

Step 1. Surface Preparation

The surface must be thoroughly cleaned to remove grease, oxides, and other impurities, which could lead to poor adhesion or coating defects. The process begins with the use of either abrasive blasting or mechanical polishing, followed by chemical cleaning. Pickling in hydrochloric or sulfuric acid removes rust and improves performance. This is followed by rinsing in deionised water to remove residues.

Step 2. Pre-Treatment

After applying a masking agent to the areas on the surface that are not to be coated with the deposit, the metal is immersed in an acidulated solution to remove the oxide film that typically forms a thin layer on the metal’s surface.

Step 3. Electro Deposition

Metal atoms at the anode are oxidized to ions, which migrate through the electrolyte and are reduced to their elemental form at the cathode. Uniform ion concentration is maintained by either stirring or air sparging the solution. The thickness of the coating is determined by controlling the plating time according to Faraday’s laws.

Step 4. Rinsing

Following the electrodeposition process, the components must undergo a series of cleaning baths to eliminate the plating solution. Post-treatment may involve a passivation process for chrome electrodeposits or heat treatment to relieve hydrogen-induced embrittlement in certain high-strength steels.

Types of Electroplating

Electroplating processes can be categorised based on the composition of the coating. Examples include chromium, copper, cadmium, tin, zinc, nickel, gold and silver plating.

Gold Plating

A gold plating process is used to enhance the corrosion resistance, electrical conductivity, and tarnish resistance of materials. A gold-coated contact is protected from corrosion by the gold coating, which prevents the oxidation of the contact’s base metal in harsh environments. Metals such as stainless steel, nickel, brass, copper, bronze, and aluminum can be used as substrates. The substrate is typically submerged in a solution containing gold ions, often with additional layers added for this purpose.

Applications: Products include components for the preservation of a lasting shine in jewelry, for low-resistance electrical contacts, and for thermal control for aerospace equipment.

Copper Plating

Its electroplating use as an undercoat greatly increases the adhesion of any other metal coatings that are then applied. Copper also conducts electricity and heat, and provides a smooth surface to facilitate further plating. This component aids the solderability of the printed circuit board and serves as a barrier in complex multilayer constructions.

Materials that can be used as a substrate include printed circuit boards, plastics that have been pretreated to make them conductive, zinc die castings, and steel.

Applications: Used in circuitry, automotive components and serves as a base layer in decorative coatings.

Nickel Plating

The applications of nickel plating include enhancing wear resistance and corrosion protection, as well as providing an attractive appearance. It is also used as a base for further plating, which strengthens the material, thereby resisting the effects of natural elements that would normally cause deterioration. The process involves electroplating from nickel salt solutions using an electric current, and the technique is often used to create multiple layers for extra protection.

Steel, copper, zinc, brass, and aluminium are frequently used as base materials.

Applications: Automotive components, engineering parts and decorative items are commonly plated by nickel plating.

Silver and Chrome Plating

Among its numerous properties, silver-plated materials offer excellent electrical conductivity, along with low contact resistance and antimicrobial properties, making them ideally suited for high-performance electrical devices. The process uses the electrolytic method to deposit metal upon conductive substrates or other objects. A wide variety of undercoats can be used, such as nickel, copper, or brass. In telecommunications and electronics, the material is used for connectors and maintaining signal integrity. Additionally, tableware is manufactured from this material for hygiene reasons.

Factors Affecting Electroplating

Before exploring materials suitable for electroplating, it is important to understand the factors that affect the process.

Current Density: The rate of electroplating and the quality of the deposit are both affected by the current density. High current densities often result in burned or porous deposits on the plated surface. Conversely, low current densities may result in a very slow rate of plating and poor coverage.
Bath Composition: The bath composition is quite crucial as the concentrations of metal ions, the pH level, and additives present can all affect the adhesion and brightness of the deposits. This can result in either dull or rough deposits.
Temperature: Temperature affects the mobility of ions and the rates of chemical reactions; variations can cause either a reduction in efficiency or cracking of the deposit.
Surface Preparation: If the surface has not been thoroughly cleaned, the outcome is likely to be peeling or blistering due to inadequate adhesion of the coating.
Agitation: Ensures the Uniformity of ion distribution; otherwise, insufficient agitation can lead to the formation of concentration gradients, which in turn cause uneven film thickness.
Anode Quality: Impurities in anodes contaminate the electrolyte, thereby lowering the purity and properties of the deposits obtained.
Plating Time: The thickness of the layer is influenced by the duration of the plating process. Overplating may cause the metal to become brittle, and underplating may weaken the protection.

Electroplating on Metals: What Works Well

Metals are the most commonly used materials in electroplating applications. Metals commonly used for electroplating include carbon steel, copper, aluminium, stainless steel, and others.

Electroplating on Carbon Steel

Carbon steel is one of the easiest and most reliable materials to electroplate. The surface of steel is easy to clean and activate, enabling electroplated coatings to bond firmly and uniformly.

Common coatings for carbon steel include zinc, nickel and chrome. Galvanizing is widely used to improve corrosion resistance, particularly for fasteners and structural components. Nickel and chrome plating are commonly used to increase wear resistance or improve the appearance of items.

Electroplating on Aluminum

Although electroplating on aluminium is feasible, the natural oxide layer poses challenges for plating. This layer impedes bonding between the substrate and the plated metal, so it must be removed using specialised pretreatment processes such as zincate conversion or double zincate conversion.

Typically, a nickel or copper layer is applied as an intermediate layer before the final plating. Although electroplating aluminium offers certain functional advantages, it is not the most economical option.

Electroplating on Stainless Steel

If the pre-treatment process is not carried out correctly, the plating layer on stainless steel is prone to peeling or delamination. To prevent this, the stainless steel surface is usually pickled and activated before a base coat is applied, such as a Wood’s nickel base coat.

Electroplating on Plastics (ABS): Special Case

Plastics are non-conductive by nature and cannot be electroplated directly. However, ABS plastic is an exception and is widely used in electroplating due to its favourable surface chemistry.

The ABS electroplating process involves several steps. First, chemical etching creates a microscopically rough surface. Next, electroless copper or nickel plating is used to establish conductivity. Once conductivity has been established, conventional electroplating can be used to build up the thickness and achieve the desired surface finish.

Although plastic electroplating can produce aesthetically pleasing, metal-like surfaces, the process is more complex and costly than using metal substrates. Therefore, it is most commonly used for decorative components in automotive interiors, consumer electronics, and household products.

Electroplating Feasibility by Material

The following comparison table has been compiled based on the ease of plating, cost and common applications of different materials:

Material	Feasibility	Pre-treatment Level	Cost	Typical Plating	Typical Applications
Carbon Steel	★★★★★	★★	★★	Zinc, Nickel	Fasteners, brackets, enclosures, automotive parts
Copper / Brass	★★★★★	★	★★	Nickel, Chrome	Electrical components, decorative parts, connectors
Aluminum	★★★	★★★★	★★★★	Nickel, Copper	Housings, heat sinks, conductive components
Stainless Steel	★★★★	★★★	★★★	Nickel, Chrome	Medical devices, food equipment, industrial hardware
ABS Plastic	★★★	★★★★★	★★★★★	Copper, Nickel	Automotive trims, consumer electronics, decorative parts

Electroplating vs Other Surface Finishing Methods

Although electroplating is not always the optimal surface finishing solution, it is highly effective when specific functional requirements must be met. When should you choose electroplating compared to other surface treatment options?

Electroplating vs Anodizing vs Powder Coating

Surface Finishing Method	Main Purpose	Key Advantages	Limitations	Typical Applications
Electroplating	Functional metal coating	Precise thickness control, good adhesion, improves conductivity and corrosion resistance	Requires chemical pretreatment, higher process complexity for some materials	Fasteners, connectors, enclosures, precision metal parts
Anodizing	Oxide layer formation (aluminum)	Excellent corrosion resistance, strong surface hardness, environmentally friendly	Limited to aluminum and some alloys, non-conductive surface	Aluminum housings, panels, consumer electronics
Powder Coating	Protective and decorative coating	Thick, uniform coverage, cost-effective, good environmental profile	Limited thickness control, reduced conductivity	Metal enclosures, frames, outdoor equipment

When to Choose Electroplating

Choose electroplating if most of the following conditions are met:

A functional metallic surface is required: The part needs electrical conductivity, solderability, or a true metal layer rather than a purely decorative coating.
Precise and controllable coating thickness matters: Tight dimensional tolerances or consistent layer thickness are critical to part performance or assembly fit.
Durability under wear or corrosion exposure is critical: The component will face friction, moisture, or corrosive environments where paint or powder coating may fail.
The part has complex geometry or recessed features: Threads, internal surfaces, or intricate shapes require more uniform coverage than line-of-sight coating methods can provide.

Conclusion

The electroplating process enhances surfaces by precisely integrating engineering principles with electrochemical methods. It protects against corrosion, is conductive, and offers durability across various industries.

Looking for electroplating services?

FSFAB provides high-quality surface finishing service for CNC-machined parts and components. We are an ISO certified company with electroplating service for metals, including steels, copper, brass, zinc alloys, and non-metals.

FSFAB offers:

0.2–1 µm (Flash coatings)
2–5 µm (Light functional coatings)
5–15 µm (Standard industrial coatings)
15–25 µm (Heavy-duty coatings)
25–50+ µm (Engineering/build-up coatings)

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FAQs

Can all materials be electroplated?

No, not all materials can be electroplated directly because electroplating requires electrical conductivity. While metals such as carbon steel, copper and stainless steel are suitable, non-conductive materials such as plastics or ceramics require special pre-treatment.

Can plastic parts really be electroplated?

Plastic parts cannot be electroplated directly because they do not conduct electricity. However, certain types of plastic, most commonly ABS plastic, can be electroplated after undergoing chemical etching and electroless plating.

What causes electroplating to peel or blister?

Peeling or blistering is usually caused by improper surface preparation, contamination or incompatibility of the substrate. The most common causes of poor adhesion during electroplating are oxide layers, inadequate cleaning, and errors in pretreatment steps.

What are the most common applications of electroplating?

Electroplating processes are widely used for fasteners, electrical connectors, automotive components, metal enclosures and decorative hardware. Electroplating offers particular advantages in applications that demand high durability, corrosion resistance, electrical conductivity or dimensional accuracy.