Working with Backdrilling in Allegro PCB Designer: Best Practices
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Note: The contact ranges for the pressfit-compliant pins might not be specified on the
actual connector specifications or even readily available. Inquiries to the manufacturer
might be required to obtain this information.
Property
BACKDRILL_PRESSFIT_CONNECTOR
Purpose
Used on pressfit connectors to permit backdrilling from
both sides of the board. Backdrill depth will not
protrude into contact range as defined by the property
string.
Usage
Optional
Value
values measured from the side
the component is placed and defined the pin contact
range (database units); this value must be obtained
from manufacturer.
Objects
Symbols
Backdrill analysis flag
N/A
Backdrill Exclusions
It might be necessary to exclude certain objects from backdrilling even though the stub
violations are present. The BACKDRILL_EXCLUDE property can be applied to symbols,
pins or vias at both the library and design levels using Edit Property (Edit > Properties).
Common examples might include the solder tail connectors or a dense pin escape
pattern in BGA areas. The PCB Designer should consult with a Manufacturing Engineer
before assuming that all the pin/via objects are suitable for backdrilling.
Property
BACKDRILL_EXCLUDE
Purpose
Excludes objects from backdrilling even though stub
may be present
Usage
Optional
Value
EXCLUDE_TOP
EXCLUDE_BOTTOM
EXCLUDE_BOTH
Objects
Symbols, Pins, Vias
Backdrill analysis flag X
