A portable electronic device packaged into a System-in-Package assembly is disclosed. The portable electronic device can include a substrate and a plurality of components mounted on the substrate and included in one or more subsystems. Interference between subsystems or from external sources can be reduced or eliminated by disposing an insulating layer over the components, forming narrow trenches between subsystems, and conformally coating the insulating layer and trenches with a metal shielding layer. In some examples, trenches between subsystems can be formed using a laser source. In some examples, trenches between subsystems can have angled walls. In some examples, the metal shielding layer can be formed using at least one of electroplating, electroless plating, chemical vapor deposition, and physical vapor deposition.