Visible to Intel only — GUID: naa1689287251688
Ixiasoft
Visible to Intel only — GUID: naa1689287251688
Ixiasoft
3.4.1. HSSI Pin-Field Breakout for VPBGA
An optimized high-speed serial I/O (HSSI) pin-field breakout routing is crucial to reduce the impact of impedance discontinuity. As demonstrated in VPBGA PCB Layout Guideline section, the high-speed transceivers ball pitch of 0.77/0.75 mm is optimized for high-speed signals, dog-bone fan-out structure is recommended, and both single ended or differential traces can be implemented depending on the routing strategy and fabrication requirement.
Typical 8 mils drill through hole via dimensions including drill hole size, max stub, and so forth are shown in the following table. Note that some of the following simulation results are based on 8 mils drill hole size vias with 16 mils pad size for thin board and better SI. Simulation results of 18 mils pad size in BGA area are also presented for comparison. As long as simulation results are good, you can also use larger pad size (such as 18 mils) for high speed signals vias.
Structure |
Dimension |
Unit |
---|---|---|
Drill hole size |
8 |
mil |
Finished hole size |
6 |
mil |
Pad size |
18 |
mil |
Anti-pad size |
24 |
mil |
Backdrill anti-pad size |
26 |
mil |
Max stub length after backdrilling |
10 |
mil |