Vacuum evaporation plating is a method of heating metal under high vacuum conditions to make it melt, evaporate, and then form a metal thin film on the surface of the plastic after cooling. Commonly used metals are low melting point metals such as aluminum.
Methods of heating metal: there are the use of resistance to generate heat, but also the use of electron beams.
When vapor deposition is performed on plastic products, the vapor deposition time must be adjusted to ensure that the resin is not deformed by the heat given off when the metal is cooled. In addition, metals or alloys whose melting and boiling points are too high are not suitable for vapor deposition.
Place the metal to be plated and plated plastic products in a vacuum chamber, using certain methods to heat the material to be plated, so that the metal evaporation or sublimation of the metal vapor encountered on the surface of the cold plastic products cohesion into a metal film.
In the vacuum conditions can reduce the evaporation of material atoms, molecules in the process of flying to the plastic products and other molecular collision, reduce the gas in the active molecules and evaporation of the chemical reaction between the source material (such as oxidation, etc.), so as to provide the density of the film layer, the purity, the deposition rate and the adhesion. Typically, vacuum evaporation requires that the pressure inside the film-forming chamber be equal to or less than 10-2Pa, and even lower (10-5Pa) pressures are required where the evaporation source and the plated product and the film quality are required to be very high.
Plating thickness 0.04-0.1um, too thin, low reflectivity; too thick, poor adhesion, easy to fall off. Thickness of 0.04 reflectivity is 90%