Hard IP blocks with physically bidirectional passageways

Hard IP blocks, such as SerDes chips, are designed with keepout zones beneath the surface interconnects, the keepout zones being spaces within the chip where there is no circuitry. Connections can be formed between surface interconnects on an under surface of the SerDes chip that faces the host die, and surface interconnects on an upper surface of the SerDes chip that interfaces without external devices. Accordingly, redistribution layers routing around an outer periphery of the SerDes chip are no longer needed, and the resistive capacitive load remains low so as not to adversely impact transmitted signals.