Direct Cable Access to Chip Package through Dense Wires Embedded in the Substrate

A high speed chip package I/O breakout solution is developed by using direct cable-package attachment through dense embedded wires in the substrate for hundred-Gbps chip-to-chip interconnects. As the method utilizes substrate embedded wires to connect the twin-axial micro-cables smoothly onto the package edge, the broadband characterization of channel electrical behavior is obtained up to 70 GHz with minimized impedance mismatch and little voltage reflection. The small insertion loss and crosstalk noise are presented for the signal integrity demonstration. Using this innovative and advanced package-cabling architecture, the high I/O count (> 300 SerDes TX/RX) can be physically achieved on a large organic substrate (>70×70mm) without a connector or socket adapter. The conventional lossy on-board PCB routings are totally replaced by the flexible and low-loss cables reaching over 3 meters for 112Gbps chip wireline communications without adding active repeater or re-timer. The big signal discontinuities and couplings on the package vertical paths such as PTHs, BGAs, and the landing pin-pads in the array field are also avoided.