An electrical or electro-optical assembly comprising a substrate comprising an insulating material, at least one conductive track present on at least one surface of the substrate, at least one electrical or electro-optical component connected to at least one of the at least one conductive track, and a continuous coating comprising one or more plasma-polymerized polymers completely covering the at least one surface of the substrate, the at least one conductive track and the at least one electrical or electro-optical component.