Backdrill

Backdrill is the process of creating vias by removing the stub in multilayer_ed printed wiring boards, to allow signals to flow from one layer of the board to another. It is a special craftsmanship of control depth drilling.

Advantages:

• Reduce interference of other signal
• Improve signal integrity
• Reduce partial plate thickness
• Reduce the use of blind and buried vias to reduce the difficulty of PCB fabrication

• Mostly are rigid boards on back
• Normally used on 8 layers or above
• Board thickness is over 2.5mm
• Minimum hold size is 0.3mm
• Backdrill is 0.2mm larger than the vias
• Tolerance of backdrill depth+/-0.05MM