A cavity or die down ball grid array package includes an interposer substrate structure attached to the die. In an example, the interposer substrate reduces the interconnect length from a board to which the package mounts to power and ground pads on a top layer of the semiconductor or integrated circuit (IC) die. In this example, the interposer substrate also removes the requirement that power and ground pads be located on a periphery of the die. Power and ground pads can be located in an interior region on a top metal layer where they can be interconnected to the interposer substrate using electrically conductive bumps or wire bond(s).