Atomic Layer Deposition Process for Barrier Applications of Flexible Packaging, 2010 PLACE Conference

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Atomic layer deposition (ALD) is a process where thin films of material are deposited in a controlled manner oneatomic layer at a time. The main advantages of ALD are the extreme degree of conformality and uniformity whichcan be obtained regardless of the orientation or shape of the substrate; there are no pinholes in the film. The abilityto do roll-to-roll coating would open huge possibilities for the technique, because barrier layers are required to avoidthe diffusion of water or oxygen through polymer or paper webs for example in the food packaging industry.

According to barrier test results, the aluminum oxide coating provided by the ALD batch process improved theoxygen and water vapor barrier as a function of coating thickness by a large amount. As an oxygen barrier, a thin 10nm coating is already able to obtain ten times lower transmission levels than the uncoated structure. As a watervapor barrier, the thickness of the polymer layer becomes practically meaningless once the thickness of the ALD–layer increases above 40 nm. With over 100 nm thickness, the water vapor transmission rates of the structures werereduced below the level of 1 g/m2/24h (23°C, 50% RH). These results encourage the continuation of investigationstowards roll-to-roll solutions of ALD processing.