A semiconductor device package having an embedded three-dimensional interconnect structure and a process for making such a package is provided. One or more ball conductors are attached to a major surface of a substrate that provides at least an electrical conduit from the ball conductor to an opposite major surface of the substrate. The substrate can also provide an interconnect between solder balls. The combination of solder balls and substrate is encapsulated in the semiconductor device package. The ends of the signal conduits are exposed on one major surface of the device package, while a portion of the ball conductors is exposed on the opposite major surface of the device package. The ball conductors and signal conduits provide signal-bearing pathways between the major surfaces of the package. Contacts created by the back grinded ball conductors are used to form a package-on-package structure by coupling with contacts from another package.