Atomic layer deposited thin barrier films for packaging

Atomic layer deposition (ALD) is a surface controlled layer-by-layer process based on self-limiting gas-solid reactions. Thin films are prepared using volatile precursors in repeating cycles until a preferred film thickness is obtained. ALD is suited for producing dense and pinhole-free inorganic films uniform in thickness. Most important commercial applications lies today in microelectronics, but they range from displays to protective coatings on silver jewellery. The purpose of this presentation is to demonstrate both the potential and the challenges of using ALD to create thin barrier layers for packaging materials. ALD can have a profound effect on the barrier values of various polymer films and polymer coated paperboards. As far as safety issues are concerned, these thin barrier films seem not to fall under the European definition of nanotechnology and migration is low enough to meet the requirements set by current European regulations. ALD can also be used to create antimicrobial thin films, and thin oxide films can be modified for improved mechanical and surface properties. It is recommended that ALD deposited thin films are protected with an additional polymer layer also providing heat sealability. Although ALD is today carried out in batch mode, the development of roll-to-roll processes will enhance the techno-economic feasibility of ALD, among others, for packaging materials.