Package-on-package systems for packaging semiconductor devices. In one embodiment, a package-on-package system comprises a first semiconductor package device and a second semiconductor package device. The first package device includes a base substrate including a first side having a die-attach region and a peripheral region, a first semiconductor die attached to the base substrate at the die-attach region, wherein the first semiconductor die has a front side facing the first side of the base substrate and a backside spaced apart from the first side of the base substrate by a first distance, and a high density interconnect array in the perimeter region of the base substrate outside of the die-attach region. The interconnect array has a plurality of interconnects that extend from the first side of the base substrate by a second distance greater than the first distance. The second semiconductor device package is electrically coupled corresponding individual interconnects.