Initially components are fixed to a jig or satellite. They then undergo an anti static and plasma cleaning procedure in preparation for the next stage. It is important to note that the components should be free from contaminants such as oil, grease or silicon release agent as these are not easily removed and have an adverse effect on the end result.

The 3 main advantages of plasma cleaning are:

1. It is a simple cleaning process at a molecular level. It passes a high voltage between electrodes in the vacuum chamber creating a plasma atmosphere. This accelerates the degassing of absorbed moisture, solvents and plasticisers leaving a contaminant free surface.

2. It improves adhesion between the component substrate and film to be deposited. This is done by breaking the molecular bonds on the substrate surface making it easier for the molecules of aluminium to attach to the component substrate.

3. It aids the successful lacquering of the component substrate. Increasing the surface energy of the substrate improves the ability of the lacquer to wet the surface. This allows the correct amount of plasma to be applied to give optimum results.

It is usual to apply a base lacquer, either by spray painting or by flow coating before metallisation, as this helps to improve the gloss levels and surface finish of the component. This lacquer has to be cured before the components undergo the metalising process.

Vacuum Metalising or PVD (physical vapour deposition) then takes place. This involves evaporating a metal (usually aluminium) under vacuum inside a chamber onto the components. During this process the jigs are rotated to help ensure complete coverage of the aluminium.

After metallisation a clear or tinted top lacquer is applied as required. In addition to providing different coloured finishes, the main purpose of the top coat is to protect the metallised finish by giving durability and scratch resistance to the components. Alternatively, a protector or silicone “in chamber top coat” can be applied.

This is a special water-clear silicone based fluid which is evaporated in the chamber as a final operation after the metalising process.

Using plasma technology, the injected protector is broken down and transformed into a solid coating on the surface of the components. This has the advantage of producing waterproof coatings that are unaffected in the temperature range -40 C to 200 C.

Used extensively in the automotive industry for headlamp and rear lamp reflectors, the coating has successfully passed automotive tests for corrosion, adhesion, water immersion and humidity.