Metallization is a kind of coating. It gives same special properties on the substrates.
Especially, Metallization on the plastic film is used for giving barrier properties on the film.
The principal of metallization is as follows.
Under vacuum condition, some metal (Aluminum etc.) is heated and metal evaporate by this heat energy.
And this vapor will condensed on the plastic film.
Then condensed vapor makes thin layer on the film.
Metallizing Machine Layout
The Structure of Metallized Film
Barrier Property Comparison