- The interconnect pitch is huge, 0.3mm-0.4mm. HBM memories have 1000s of I/Os
- The inductance of the solder balls and the impedance discontinuities in the path mean the logic below still has to have big energy-hungry I/O drivers
- If you want to stack more than one die, you need something expensive like through silicon vias (TSV)
- The interconnect pitch is huge, 0.3mm-0.4mm. HBM memories have 1000s of I/Os
- The inductance of the solder balls and the impedance discontinuities in the path mean the logic below still has to have big energy-hungry I/O drivers
- If you want to stack more than one die, you need something expensive like through silicon vias (TSV)