5.2 HDI PCB Rules

The high-density BGA package featured by SAMA5D27 requires HDI (High-Density Interconnect) PCB features such as blind and buried vias, and small trace width and clearance. It also requires the via-in-pad feature.

The following design rules are recommended for the PCB area below and near the MPU package:

• Blind and buried vias: 0.25 mm diameter and 0.125 mm hole size
• BGA land size: 0.25 mm diameter with 0.05 mm solder mask expansion
• Trace width/clearance: 0.1/0.075 mm

Further away from the MPU package (clearance larger than 5 to 10 mm), more relaxed rules can be adopted, such as:

• Through hole vias: 0.4 mm diameter and 0.2 mm hole size
• Trace width/clearance: 0.1/0.1 mm