1. A circuit board assembly comprising:a baseboard having a mounting surface to which a first coupling pad is attached, the first coupling pad providing a first pattern of electrical contacts that correspond to at least a first type of integrated circuit; and
a dual-sided interposer substrate comprising:
a stack of two or more printed circuit boards (PCBs) having a top surface with a top ground plane and a bottom surface with a bottom ground plane;
a second coupling pad attached to the top surface of the dual-sided interposer substrate, the second coupling pad providing a second pattern of electrical contacts that correspond to at least a second type of integrated circuit; and
one or more stacked vias formed through the stack of PCBs, each stacked via electrically connecting between respective electrical contacts of the first and second coupling pads to form a corresponding communication channel.