Cadence PCB Best Practices

Working with Backdrilling Backdrilling October 2019 40 Product Version 17.4-2019 © 1999-2020 All Rights Reserved. Selecting the yellow cell on the layer pair row from BOTTOM to LAYER_4_P opens a dialog to explain the violation: Note: The fabrication vendor can adjust the To Layer to meet their minimum stub length after backdrill which would result in them moving it to LAYER_5 with the stub spanning two layers. All Backdrill data will still be generated, even when these Warnings exist. Tip Backdrill Analysis can take into consideration the specified Manufacturing Stub Length and make adjustments during layer pair creation by setting a special environmental variable. ■ Set the environmental variable BACKDRILL_LAYER_PAIR_ADJUSTMENT ■ Select Layer Pair Initialization button in the Layer Pairs tab

• Cover
• Contents
• Backdrilling
• Introduction
• Licensing
• Prerequisites
• Backdrill Commands, Properties, Parameters, and Subclasses
• Terminology
• Net Identification
• Applying the BACKDRILL_MAX_PTH_STUB Property in Constraint Manager
• Stub Calculation
• Pin Plating Restrictions
• Applying the Minimum Pin Plating Property
• Pressfit Connectors
• Backdrill Exclusions
• User Overrides
• Fabrication Vendor Backdrill requirements (Reference Only)
• Setup and Analysis User Interface
• Initially Launching the Backdrill Setup and Analysis Dialog Box
• Prior to executing Backdrill
• Padstack Parameters Tab of the Backdrill Setup and Analysis Form
• Flag Codes tab of the Backdrill Setup and Analysis form
• Final Backdrill Steps – Executing Backdrill
• Manufacturing Stub Length Analysis (Drill Parameters Tab)
• Effects of Setting a Manufacturing Stub Length:
• Layer Pairs tab feedback – Depth column yellow cells:
• Backdrill Canvas Display Controls
• Backdrill Data Show Element visibility (Pins/Vias)
• DRC and Shape Voiding
• Board Testability
• NC Drill and Legend Output
• Enabling Backdrill Output
• NC Backdrill Legends
• Legend Customization
• Backdrill Cross Section Chart Display