Embodiments of the invention relate to a package-on-package (PoP) assembly comprising a top device package and a bottom device package interconnected by way of an electrically interconnected planar stiffener. Embodiments of the invention include a first semiconductor package having a plurality of inter-package contact pads and a plurality of second level interconnect (SLI) pads; a second semiconductor package having a plurality of SLI pads on the bottom side of the package; and a planar stiffener having a first plurality of planar contact pads on the top side of the stiffener electrically connected to the SLI pads of the second package, and a second plurality of planar contact pads electrically connected to the inter-package contact pads of the first package.