What’s Good About Allegro PCB Editor Backdrill Capability? New Capabilities in 17.2!


Courtesy of PCB Piezotronics, Inc.

The 17.2 Allegro PCB Editor has improved backdrill capabilities.

Backdrill data is now stored in the library padstacks and utilized at the design level during the analysis and backdrill generation process. Padstacks which do not have pre-defined backdrill information can be automatically updated at the design level by the entering the backdrill criteria prior to running backdrill. Design layers which are backdrilled will have Route Keepout Shapes generated to ensure design integrity is maintained with separate padstack definition controls for the backdrill start layer, internal layer, and negative layer anti-pad geometries without the need of custom padstacks or scripts. All backdrill data is available on the individual Pin/Via objects displayed on the canvas or by simply querying the object using Show Element, and generating the Backdrill Legends and detailed Backdrill Report.

Please read Mike's blog post 'Why Move Up to Allegro 17.2-2016? New Enhanced Backdrill Capability (Reason 4 of 10)'.

Here are the main areas of improvement for backdrill support:

  • New/Updated Backdrill Properties
  • Padstack Editor Backdrill Data Support
  • Backdrill Setup and Analysis
  • Backdrill Display Control
  • Backdrill Data Show Element Visibility (Pins/Vias)
  • Backdrill NC-Drill Legend Updates
  • Backdrill Cross-Section Chart Display
  • Test Prep Backdrill Awareness
  • DRC and Shape Voiding
  • Manufacturing Support
  • Signal Integrity Support
  • Report Support

I’ll be highlighting a few of these.

New/Updated Backdrill Properties


  • Property which allows pin/via to be backdrilled from the component placement side.


  • Property changed from a Boolean to Enumerated type to support TOP/BOTTOM/BOTH side values.
  • Property cannot be mirrored if it is assigned to a symbol.

Padstack Editor Backdrill Data Support

  • Secondary Drill Tab – Backdrill Section
    • Backdrill diameter
    • Backdrill drill legend symbol (Figure, Character, Size)
    • Enabling section will add additional rows under Design and Mask Layers Tabs:


Design Layers Tab

  • Regular Pad
  • Anti Pad
  • Keep Out


Mask Layers Tab:


Summary Tab:



Backdrill Setup and Analysis

Main interface to setup Layer Pairs, Manufacturing stub length, and Padstack Parameters.

Layer Pairs Tab:


Drill Parameters Tab (New):


Flag Codes Tab (New) – Legend for symbols generated on MANUFACTURING BACKDRILL-FLAG-TOP, BACKDRILL-FLAG-BOT and BACKDRILL-FLAG-ANY subclasses, which identify why a backdrill was not generated:


Padstack Parameters Tab (New) – Parameter values used to update/generate backdrill data in design-level padstacks:


Backdrill Canvas Display Controls

Setup –> Design Parameters –> Display Tab:



Backdrill Data Show Element Visibility (Pins/Vias)

Backdrill Data reported on pins/vias at the bottom of the show element information window:


Backdrill NC-Drill Legend Updates

Manufacture –> NC –> Drill Legend:



Backdrill Cross Section Chart Display

Manufacture –> Cross Section Detail…

Backdrill span in cross section detail will show a tapered end before just below first active conductive layer (Must Not Cut Layer):



Manufacturing Support

IPC-D-356 – Output will include any backdrill data with an option to ignore the backdrill data during output:


Extracta Support

API and extracta program can be used to get backdrill data on pins/vias.

Report Support

Tools –> Quick Reports –> Backdrill Report

New detailed backdrill report added to standard reports:

  • Lists all backdrill data for the backdrilled pins/vias
  • Lists total backdrills and manufacturing stub length


You can read the highlights of the “10 Top Reasons to Move Up to Allegro 17.2-2016 Release” and review more details at the 17.2 Launch Page. In addition, you can download the Rapid Adoption Kit (RAK) titled “Enhanced Backdrill: Enhanced Backdrill in Allegro PCB Editor 17.2

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