Surfaces for electric mobility (part 2): New plating concepts for battery casings, busbars, connectors, etc.

The first part of "Surfaces for electric mobility" has shown how technological demands on surface finishing are changing. The second part deals with plating solutions for specific components such as busbars, connectors and battery casings.

Electrical components – insulation versus conductivity

All-electric and plug-in hybrid vehicles are fitted with a lot more electrical and electronic components than combustion engine-driven vehicles. This fact is also driving a growing demand for components such as connectors, printed circuit boards and busbars. Depending on the component and its application, reliable conductivity or electrical insulation can be just as important as power transmission and firm contacting. Apart from long-lasting corrosion and wear protection, surface coatings also need to provide these additional properties, from conductivity to insulation. Platings such as gold, tin and silver or even combination layers are suitable for these types of specification profiles.

Coating systems for electric mobility components

One example is metal rails, such as busbars. They are mostly made of copper or aluminium as base materials and needed to conduct high-voltage currents for power transmission. To protect and improve the functional properties of the busbars, platings such as electroless nickel, tin, silver, galvanic nickel and combinations of these processes are used. Copper busbars can be tin-plated, for example, to ensure sustained low contact resistances at connections. The plating also protects against corrosion at the same time.
Electroless and galvanic nickel plating, tin plating, silver plating and layer combinations are not only suitable for busbars. These plating systems are also appropriate for other components used in electric mobility applications, such as screw connections and connectors. These special-purpose systems are designed in such a way that defined contact resistances can be produced for connecting elements.

Zinc-nickel for lightweight construction and electric mobility

In automotive manufacturing too, proven plating processes such as zinc-nickel are an essential technology in the field of electric mobility and above all lightweight construction. Zinc-nickel not only improves the corrosion protection and therefore the service life of plated parts, further advantages of the zinc-nickel process with nickel insertion rates of 10 to 15% are its compatibility with aluminium, as there is no contact corrosion. Moreover, zinc-nickel plated components can also be bonded. The process is also suitable for plating ultra-high-strength steels, where it can minimise liquid metal corrosion and hydrogen-induced brittle fracture. Used in composite design, Zn-Ni-plated components can reduce contact and crevice corrosion. Zinc-nickel surfaces also have other advantages for components used in the field of electric mobility: Depending on the specific application, zinc-nickel can be used for contacting in the high-voltage range and it also has a positive impact on breakdown wear.

Plating processes for battery casings

The battery is the key component in an electric car. It is the most sensitive and at the same time the most expensive part and accounts for 30 to 50 per cent of the total cost of the vehicle. It is therefore all the more important to protect the battery and make sure its service life is as long as possible. Protective casings are often made of aluminium or even innovative types of high-strength steels. Proven corrosion protection concepts using electroplating methods such as zinc-nickel systems, partly with sealing, can be considered for plating these protective covers or battery casings, including their lids and mountings. They not only protect from corrosion, they are also temperature-resistant. Steel sheets bonded with plastic are also sometimes used for the battery casings and their lids. Conventional electroplated coatings can also be used for such metal-plastic composites, which have proven their efficiency for decades in the automotive industry for other highly stressed components.

Laser-processed cathodic dip coating

Battery trays, underbody panels and similar components can also be protected from corrosion with cathodic dip coating. Downstream laser processing is particularly useful for creating paint-free areas on the black surfaces. These areas can be helpful to ensure electrical conductivity, to enable the flow of current and also to attach ground cables. Coating-free surfaces can also be an advantage for downstream processing stages such as welding.

Other components for electric vehicles that can benefit from conventional electroplated corrosion-resistant coatings include parts for start-stop devices, skid mounts, metal pipes and tubes, shells, fixing straps and many more.

Coating partners provide support right from the development stage

Specialists in surface finishing technology can offer their support in developing new, requirements-based surface finishing solutions for the electric mobility sector. These include, for example, jointly adapting designs to suit the electroplating process with the aim of minimising overall coating costs. Project management also plays a key role here. The right coating partner can assess projects in terms of their surface requirements, actively supervising the process from the sample to the prototype to series production and developing the components to series maturity.

Please also read the first part on the topic of Surfaces for electric mobility



busbars for e-mobility

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