Moisture barrier films deposited on PET by ICPECVD of SiNx

In this work, the inductively-coupled PECVD (ICPECVD) technology has been used to deposit moisture barrier coatings in the range of 25-1 200 nm on a 100 m thick polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) substrate. The water vapour transmission rate (WVTR) was determined at room temperature using the Calcium test method. A decrease in the metallic calcium layer thickness leads to an increase in transmission coefficient, related to the amount of absorbed water as a function of time. At a coating thickness of around 25 nm, the WVTR is reduced to less than 0.1 g · m-2 · d-1. With increasing SiN thickness, the transmission rate decreases to an excellent value of 2 × 10-3 g · m-2 · d-1.