The Back Drill Spans dialog is used to create and manage defined Back Drill Spans in the design. A Back Drill Span defines the layers required to be back drilled, from either the top or bottom to an inner layer.
Shortcuts
Menu: Setup
Default Keys: T
Command: Technology
Locating this option
Available from: Setup menu > Technology option > Back Drill Spans tab
Using This Dialog
Navigation
The buttons to the right side of the dialog are used to navigate the grid, the general common buttons are detailed on the Technology Navigation page.
The Auto Gen button take you to the Auto Generate Back Drill Spans dialog. This creates a list of possible Back Drill spans, which can be included in the design.
The View Layers button takes you to the Layer Stack Preview dialog, which offers a simple view of the layer stack. This view will show the Back Drill spans currently in the design.
Layer Span Edit Pane
First you must provide a unique Name for the Span, which has to be unique across all Back Drill Spans and Layer Spans. Then use the Start Layer and Stop Layer drop down lists to produce a unique Back Drill span.
Back Drill Depth
The Back Drill Depth is the depth of the oversized drill hole after Back Drilling. This value takes into account the Back Drill Stub Length, and is measured from the top or bottom of the board to the inner electrical ‘Stop’ layer of the Back Drill span (this does not include the thickness of the stop layer). It is calculated from the layer thicknesses, or can be specified as an explicit value by unchecking this option and typing the value required. If you have specified layers thicknesses, you are likely to want to use these.
If the drill depth is
Calculating Back Drill Spans
Back Drill span calculations are shown on the Back Drill Rules page.
Related Topics
Technology Overview | Back Drilling | Back Drill Rules | Layers | Layers Spans | Layer Stack Preview | Back Drill Auto Gen | Micro-vias | Insert Via | insert Track