Working with Backdrilling in Allegro PCB Designer: Best Practices
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Note: The layer pair shift resulted in a couple of bottom side backdrill layer pairs to be
combined with all others shifting up or down one layer depending on the backdrill side.
To Layer Must Not Cut Layer Plunges To Layer Must Not Cut Layer Plunges
LAYER_7_P LAYER_6 10
→
LAYER_7_P LAYER_6 21
LAYER_6 LAYER_5 11
Tool Tip – Once the layers pairs are regenerated, Backdrill will be out of date. Select
the Backdrill button to regenerate backdrill data for pins/vias using the new layer pairs.
• With the "BACKDRILL_LAYER_PAIR_ADJUSTMENT" environmental variable set, you
will see the following message. Select the OK button to continue.
In the backdrill analysis log, the Remaining Stub Len column will report the distance
from the shifted Must Not Cut Layer to the actual connection layer.
Tool Tip – The Remaining Stub Len column is the distance from the shifted Must Not
Cut Layer to the actual connection layer. ("To Layer" + "Dielectric" thickness).
Maximum PTH Stub column is the Electrical Stub defined on the net using the
BACKDRILL_MAX_PTH_STUB Property.
