Cadence PCB Best Practices

Learn more at Cadence Online Support https://support.cadence.com © 2024 Cadence Design Systems, Inc. All rights reserved worldwide. Page 3 Working with Backdrilling in Allegro PCB Designer: Best Practices Contents Purpose ....................................................................................................................... 4 Terms .......................................................................................................................... 4 Overview ...................................................................................................................... 5 Licensing ..................................................................................................................... 6 Prerequisites ................................................................................................................ 6 Backdrill Application Information .................................................................................. 6 Backdrill Flow in the Allegro PCB Designer ................................................................. 7 Net Identification .......................................................................................................... 8 Applying Property in Constraint #Manager .................................................................. 8 Stub Calculation ........................................................................................................... 9 Pin Plating Restrictions ............................................................................................. 10 Applying the Minimum Pin Plating Property .............................................................. 12 Pressfit Connectors .................................................................................................. 15 Backdrill Exclusions .................................................................................................. 16 User Overrides .......................................................................................................... 17 Fabrication Vendor Backdrill requirements (Reference Only) ................................... 20 Setup and Analysis User Interface ............................................................................ 21 Prior to executing Backdrill ....................................................................................... 31 Padstack Parameters tab of the Backdrill Setup and Analysis form .......................... 31 Flag Codes tab of the Backdrill Setup and Analysis form .......................................... 33 Final Backdrill Steps – Executing Backdrill ............................................................... 34 Manufacturing Stub Length Analysis (Drill Parameters Tab) ..................................... 35 Effects of setting a manufacturing stub length .......................................................... 36 Layer Pairs tab feedback – Depth column yellow cells ............................................. 36 Backdrill Canvas Display Controls ............................................................................ 40 Backdrill Data Show Element visibility (Pins/Vias) .................................................... 41 DRC and Shape Voiding ........................................................................................... 42 Board Testability ....................................................................................................... 43 NC Drill and Legend Output ...................................................................................... 46 Enabling Backdrill Output .......................................................................................... 46 NC Backdrill Legends ............................................................................................... 47 Legend Customization .............................................................................................. 50 Backdrill Cross Section Chart Display ...................................................................... 51 Support ..................................................................................................................... 51 Feedback .................................................................................................................. 51

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