Summary: Many products we use daily are coated in thin chemical films.
When you see something that has been anodized, you can bet that it has gone through some kind of thin film deposition system. Thin films make lots of our current technology possible, and the PVD coating equipment used to apply these films have become an important part of advanced manufacturing. What they are, and how they work, depend a lot on the kind of system used.
Coatings come in two basic varieties: chemical and metallic. There are other variations, but most processes bond either chemicals or metals to a substance. So depending on the chemicals in question, the expectation is very different. For example, anti-glare lens coatings are a thin film that consist of chemicals designed to resist glare.
The Coating Mechanism
A PVD system breaks down a chemical that is meant to coat an object, usually called the substrate. This can mean that intense heat is used to break a solid form into a gas. Once that transition occurs, the molecules come to rest on the substrate. The substrate has to be placed in a vacuum chamber during this process, mainly because of sensitivity to temperature. The same heat that can break metal into gas would obliterate plastic in moments.
The solution is a temperature controlled space for the substrate. The vacuum provides that space, and allows the gaseous particles to come to a rest on the substrate. The substrate is rotated in the meantime, which gives it an even coating of chemicals. The end result is a smooth finish, and a clean application with fewer wasted materials.
Bio: Denton Vacuum, LLC specializes in equipment used in advanced manufacturing, including optical coating devices.