Why aluminum without a protective coating fails in cooling systems and power electronics

Aluminum poses specific challenges in power electronics that cannot be overcome without targeted surface treatment.

• Aluminum oxide (Al₂O₃) prevents reliable solder joints and permanently increases the electrical contact resistance.

• Galvanic corrosion occurs upon contact with copper, steel or brass.

• Under screw pressure, aluminum undergoes plastic deformation, leading to arcing at busbar contacts.

• Copper atoms diffuse into the aluminum and form brittle intermetallic phases.

Chemical nickel plating on aluminum solves all four challenges with a single coating system.

Benefits of a chemical nickel (ENiP) protective coating for aluminum components in cooling systems and power electronics

Chemical nickel-phosphorus serves multiple functions simultaneously. The coating system is specifically tailored to meet requirements for solderability, corrosion protection, or mechanical stability.

Solder joints and bondability

Chemical nickel plating provides a metallically pure surface for aluminum cooling systems, ensuring reliable solder joints. During soldering, an intermetallic phase (Ni₃Sn₄) forms, creating a strong, material-bonded joint. The hard nickel layer stabilizes the bond pad structure and can thus reduce the risk of cratering during wire bonding.

Corrosion protection and diffusion barrier

High-phosphorus variants containing more than 10% phosphorus form an amorphous layer without grain boundaries. This layer isolates the aluminum from coolants, casting compounds and adhesives, and prevents galvanic corrosion in mixed assemblies with copper, steel or brass.

Our options

We offer chemical nickel plating on aluminum with various additive systems, such as PVD top coats, to optimally combine corrosion protection and solderability.

Electrical contact stability

The nickel layer prevents the reformation of the high-resistance aluminum oxide layer. The electrical contact resistance remains consistently minimal. In busbar contacts, it prevents aluminum creep under screw pressure.

Uniform coating thickness and dimensional accuracy

The electroless process ensures a uniform coating thickness of 3.0–6.0 µm, even in blind holes, threads, and complex cooling structures. The process is suitable for components with tight tolerances, mating surfaces and sealing seats.

FAQ: Frequently Asked Questions about chemical nickel on aluminum