An implantable medical device including a plurality of components on a substrate, and a biocompatible multi-layer coating applied at least in part by vapour deposition to conform to and sealingly cover at least a portion of the components and/or the substrate. The coating is applied in at least two sets of layers, wherein each set has at least one layer formed by dissociation of a polymeric precursor and then deposition of that precursor, and another layer is a biocompatible liquid.