ABSTRACT
Today, car lighting reflectors and even bezels have reached highly complex shapes and sometimes extreme sizes also. The tendency to abandon lacquering has necessitated new challenges to metallize such demanding parts. Especially reduced adhesion of the coating and outgassing from the parts may affect aluminium quality or may cause hazy appearance of these parts during the lifetime of the car by droplet condensation.
These problems can be solved by a process sequence including plasma pre-treatment, metal sputtering, and plasma polymerization in one load locked machine. An efficient vacuum system and the plasma pre-treatment ensure clean vacuum conditions for metallizing the parts. Further outgassing from the parts can be blocked by a plasma polymerized base coat. The following sputtering process yields very good quality and coverage of the metal layer (usually aluminium but other metals as well) on the less exposed areas, even behind recesses. Subsequently, first a corrosion protective layer and a high surface energy top coat (that suppresses hazing effects by spreading out any condensing vapours to some optically neutral layer) are deposited by plasma polymerization. As a result, the overall reflectance, corrosion and hazing resistance of aluminium mirrors sputtered within such a process sequence over complex reflector parts was found to be superior to conventionally evaporated ones.
