22.214.171.124. R-Tiles Features and Capabilities 126.96.36.199. R-Tile Design Layout Examples 188.8.131.52. Landing Pad Cut-out Optimization of AC Coupling Capacitor 184.108.40.206. R-tile HSSI Breakout Routing in BGA Field Area and MCIO connector Pin Area 220.127.116.11. AC Coupling Capacitor Placement Around MCIO Connector 18.104.22.168. PCIe Gen5 Add-in Card Edge Finger Breakout Design Guidelines
1.3.6. Via Drill Size
- The aspect ratio (AR) is the ratio of a via length or depth to its drill hole diameter. An AR of 15 is a common manufacturing capability provided by most PCB vendors. PCB vendors define the exact AR based on the board thickness specified by their manufacturing capabilities.
- To meet the target differential via impedance, the optimized anti-pad size is usually larger than the default via anti-pad which may cause a reference issue for breakout routing in the BGA area. Check via impedance with time domain reflectometry (TDR), and use a teardrop or wider trace segment in the breakout area for a smooth impedance transition to the global area.
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