PSA B15 4140 Electrolytic Chromium Plating on Plastic Parts

The “PSA B15 4140 Electrolytic chrome plating on plastic parts” standard, developed by the French car manufacturer PSA Group, now part of Stellantis, applies to electrolytic coatings on plastic parts.

These electroplatings, such as chrome-nickel or chrome-nickel-copper, can have a weakening effect on parts subjected to stress. Consequently, fastening systems (e.g., clips) should either be unplated or designed to withstand the limitations of assembly and disassembly after chrome plating. On the other hand, in snap fasteners, the snap tools must be free of metal sludge.

Two coating categories have been defined according to the position of the parts:

• Exterior parts of the vehicle
• Vehicle interior parts

When it comes to chrome-plated plastic parts that have a coating (e.g., varnish) applied, the technical specifications of this standard, as well as the technical specifications book for that coating, must be considered. For example, the PSA B72 0200 standard applies to exterior parts with varnished chrome plating, and the PSA B62 0400 standard applies to interior parts.

Requirements are defined according to the overall performance provided by the material in the following aspects:

• Regulations and consumer standards
• Appearance in its new state
• Aging characteristics before use
• Post-use aging characteristics
• Compliance with the core competencies of PSA standards.
• Technical specifications (mechanical, thermal)

Furthermore, the basic requirements are the subject of a classification that ensures their traceability according to the automotive engineering system.

In vehicle interiors, surface selection should be based on the temperature to which the part is exposed. This information is provided by PSA to the supplier based on the temperature maps (measurements or simulations) available in the project. By default, the supplier may use the general maps given in the PSA B62 0300 standard. Depending on the exposed temperature, the surface properties are as shown in the table given in the standard.

Each proposed finish must conform to the required standard. (The color is defined by 3 letters followed by 3 digits, which describe the surface treatment.) For example, HDX M0001 refers to a high-gloss exterior vehicle chrome finish, and HDX M018 refers to a matte interior vehicle chrome finish. Except for specific requirements indicated in the part layout, the finishes to be used are as listed in the table.

In the case of nickel duplex or bi-nickel plating, the total nickel thickness should preferably consist of a maximum of 2/3 semi-bright nickel and a minimum of 1/3 bright nickel. The supplier has the freedom to suggest an additional nickel layer, in which case a detailed measurement of the thickness + test result must be submitted to the PSA materials department for approval.

The PSA B15 4140 standard primarily outlines requirements for applying electrolytic chrome plating to plastic components for automotive use. This standard covers aspects such as plating thickness, adhesion, corrosion resistance, thermal cycling, and appearance, ensuring that plated plastic parts meet the demanding requirements of vehicle exteriors and interiors, such as grilles, trims, emblems, and bumpers.

This standard reflects the automotive industry's long-standing reliance on chrome-plated plastics to achieve a superior metallic shine while reducing weight compared to solid metal parts.

Since plastics are not conductive, direct electroplating is not possible. The process, often referred to as coating, involves several steps:

• Molding and preparation: Parts are typically produced by injection molding from coatable resins that provide excellent adhesion, such as acrylonitrile butadiene styrene (ABS) or PC/ABS blends.
• Etching: The plastic surface is chemically etched (usually with chromic acid) to create microscopic pits for mechanical anchoring.
• Neutralization and activation: Residues are removed, and a catalyst (usually palladium) is applied to initiate conductivity.
• Non-electrolytic plating: A thin layer of copper or nickel is chemically coated (without electricity) to make the surface fully conductive.
• Electrolytic plating: The part is immersed in electrolytic baths.
• Copper for leveling and thickening.
• Nickel for corrosion protection and shine (semi-gloss and high-gloss finishes).
• Finally, a thin layer of chromium (0,3–1 μm) for the characteristic bright and hard surface.

This multi-layered approach guarantees durability through testing under standards such as PSA B15 4140, including CASS (copper accelerated acetic acid salt spray) for corrosion and thermal shock resistance.

Chrome-plated plastic parts are widely used in the automotive industry due to their lightness, cost-effectiveness, and luxurious appearance.

Traditional hexavalent chromium treatments are highly effective but are toxic and carcinogenic. Regulations such as RoHS have led the industry to switch to trivalent chromium plating, which offers similar aesthetics and performance with a lower environmental impact.

Stellantis has started to use no chrome at all, aiming to eliminate traditional chrome plating entirely and opt for alternatives such as physical vapor deposition or painted surfaces in order to promote sustainability.

PSA B15 4140 is a significant historical milestone in providing high-quality electrolytic chromium on plastics, enabling the brilliant accents that have defined automotive design for years. While the technology evolves towards more environmentally friendly methods, the principles of adhesion, multilayer deposition, and performance testing remain fundamental.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its customers, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "PSA B15 4140 Electrolytic chrome plating on plastic parts" standard.