Thermal vacuum coating is one the simplest and oldest of the physical vapor deposition techniques. A solid sample of material is heated in a vacuum and the particles that evaporate travel though the chamber and condense on the substrate.

Thermal evaporation vacuum coating is most often used for depositing metal or metal oxide contacts on flat substrates. It is difficult to control the thickness of the deposit and surface irregularities may cause shadows. The temperature of the source determines the speed of the atoms as they hit the substrate thus making it possible to limit damage to the substrate. This is a relatively rapid technique suitable for roll to roll processing.
For more information see photonics wiki:
http://photonicswiki.org/index.php?ti...