Surface treatment and insulation

Surface treatment: Avoid oxidation of the surface

Like all other metals, copper will oxidize over time. When copper oxides form on the surface, electrons can no longer move freely, which lowers the conductivity.

Temporary or permanent surface treatments can protect the metal from oxidation and maintain the intended conductivity. For electrical applications, the typical choice is a permanent surface treatment. Oxidation occurs faster when the part is not conducting a current, so a permanent surface treatment is a good way to protect an electrical contact throughout the contact's lifetime.

A permanent surface treatment is typically a coating with another metal, e.g. silvering, gilding, tinning, nickel plating – or a combination.

Nickel is typically used as an undercoating between the copper item and the final coating, but there are also examples of nickel plating as the only surface treatment.

Tin plating and tin whiskers

Tin is a very soft metal, which maximizes the electrical contact between two tinned components. Tin also has the advantage of oxidizing very slowly. This makes tin an optimal surface treatment for contacts and components that are left without electrical contact for a long time and are therefore more prone to oxidation.

Tin plating can be either matte or glossy. It is recommended to choose the matte tin to reduce the risk of tin whiskers.

Tin whiskers are thin strands of tin that can appear on a tin surface. They protrude from the surface like hair when exposed to static electricity. The threads can become relatively long, and they increase the risk of unwanted electrical contact with other parts of the installation.

Adding a coat of nickel under the tin plating allows for a thinner tin coat, which will reduce the risk of tin whiskers. An undercoating with nickel is especially useful when the electrical components will be mounted close to each other with a greater risk of unwanted electrical contact through small whiskers.

Temporary surface treatments

The purpose of temporary surface treatments is mainly to protect the item from oxidation during transport or storage. Busbars will often be treated with a thin coat of oil (BTA) after production, after which they can be stored without significant oxidation.

It is also advisable to wrap items in plastic during transport and storage to reduce air circulation around the metal.

A third option is to lubricate the item with petroleum jelly, which forms a relatively airtight film around the metal.

Insulation of copper

Insulation on copper parts in electrical installations is an effective way to avoid electrical contact with other parts. Insulation can be permanent, such as powder coating or heat shrink, or it can be loosely mounted, such as mesh.

Insulation is available in all colours, sizes and thicknesses depending on your requirements and specifications. Different types of insulation have strengths and weaknesses depending on dimensions, space requirements, temperature, electrical specifications and the installation environment.

The following types of insulation all offer protection against unwanted electrical contact, moisture, chemicals and other environmental factors. This reduces the risk of corrosion and consequently reduced electrical conductivity.

Fiberglass

Fiberglass is at the coarser end of the insulation spectrum. In addition to protecting against electrical contact with other parts to avoid short circuits or electric shocks, fiberglass provides mechanical protection against shock and vibrations. This is especially useful with braided busbars, as the ultra-thin threads are easily damaged.

The surface is coated with silicone, which is self-extinguishing and flame-resistant.

Fiberglass insulation is shaped like a cylinder, which can be cut to the desired length and mounted on the busbar like a sock.

Heat shrink

Heat shrink tubing is a more compact and form-fitting insulation than fiberglass. This is especially useful with bus bar fixtures, where the parts are placed very precisely and sometimes close to each other. Like fiberglass insulation, heat shrink tubing also provides mechanical protection against impact and vibrations.

Heat shrink tubing is loosely mounted around the busbar and shrunk to approximately 50% of the original size using heat. To ensure a snug fit around the busbar, it is important to choose the right tube diameter and shrink ratio.

Powder coating

Powder coating is a very compact type of insulation, but it offers little in terms of mechanical protection.

The insulation layer consists of an epoxy coating, which is applied electrostatically and cured in an oven for about 30 minutes. The result is a very even and form-fitting insulation layer that is suitable for installations with limited space.

Powder coating has a significantly higher dielectric strength than fiberglass insulation and heat shrink tubing and is particularly suitable for high-voltage installations.