Issue link: https://resources.pcb.cadence.com/i/1180264
Working with Backdrilling Backdrilling October 2019 23 Product Version 17.4-2019 © 1999-2020 All Rights Reserved. ■ Inner layer pads in the backdrill path should be removed. ■ Outer layer backdrill entry pad is normally reduced so it is slightly larger than the primary drill with would be drilled away by the backdrill. (Primary Drill + 5 mils) ■ Outer layer backdrill solder mask opening is normally 6 – 10 mils over the backdrill size Note: Consultation from a fabrication vendor is advised to determine which rules are going to work best. The library padstacks are required to be updated so that each design have consistent backdrill rules. With the backdrill data being stored in the padstack this allows the information to be updated at the library and design level to take full advantages of this enhanced backdrill functionality. No special scripts and SKILL routines to maintain design integrity. Tip Although the backdrill data can be entered in the padstack at either the library or the design levels, it is recommended to maintain the backdrill data at the library level for a consistent set of backdrill rules and guidelines. Setup and Analysis User Interface The heart of the backdrill application is the Backdrill Setup and Analysis user interface located in the Manufacturing – NC menu of Allegro PCB Designer. This form controls the side of the board to be backdrilled from, object types, and number of passes per side. Analysis in the form of graphical violations and a detail log file is provided when the Analyze button is selected. The form facilitates experimentation by editing pass sets and reviewing backdrill plunges per layer pair to eliminate underutilized backdrill layer pairs. Multiple analysis runs can be performed for fine tuning and backdrill results selecting the Backdrill button to commit Initially Launching the Backdrill Setup and Analysis Dialog Box Upon invocation, the Backdrill Pairs Question dialog is displayed. It can be used to produce a similar result to the Cadence default passes of previous versions with some fine tuning by defining the layer pairs based on the deepest backdrill layer by side and have them automatically generated.