Disclosed herein is a device comprising a first package having a first side with a plurality of connectors disposed thereon and a second package mounted on the first package by the connectors. A molding compound is disposed on the first side of the first package and between the first package and the second package. A plurality of stress relief structures (SRSs) are disposed in the molding compound, the plurality of SRSs each comprising a cavity free of metal in the molding compound and spaced apart from each of the plurality of connectors.