Vacuum metallization, sometimes also called ‘Physical Vapor Deposition’ (PVD),
is widely used to deposit a thin aluminum layer on plastic parts. Applications
include automotive interior parts, car lighting components, plumbing
accessories, jewellery components, packaging foils etc.
The metallic coating can be deposited on the outside of a part, or on the
inside of transparent Xantar PC parts. In the latter
case, the metallic coating is protected by a layer of plastic. The ultra thin
metallic coating on the outside of a vacuum metallized part must be over
coated with a transparent topcoat to improve its abrasion resistance and to
protect it against environmental influences, like humidity. Gold and other
colors can be obtained by dying the top coating.
High-heat thermoplastics used for car lighting can withstand the high
temperatures inside the lamp unit, but can outgas volatile materials that
condense on the cooler areas within the reflector, leading to a hazy
appearance that impairs optical performance. A high surface energy, haze
preventing topcoat may be deposited by thermal SiOx evaporation from a heated
boat or a crucible placed in the vacuum chamber.
Arnite XL is an exception to this and does not outgas and a topcoat is not
required.
In order to obtain a high-gloss and highly reflective aluminium layer on a
matt or glass- or mineral filled plastic part, the plastic surface must be
undercoated with a lacquer.
The special cases of vacuum metallization are :
Vacuum evaporation
Sputtering
