Fanout Options

Parent page: PCB Dialogs

The Fanout Options dialog.

Summary

This dialog allows the designer to specify fanout and escape routing options. Typical fanout behavior is for used inner pads to first be fanned out using the traditional dog-bone (a short route with a via on the end) to access another layer, and then from the via they are escape routed out just beyond the edge of the device, working through the available routing layers until all pads have been escape routed. Ultimately, this makes routing connections to them much easier.

Fanout and escape routing is done in accordance with the applicable design rules, including the Fanout Control rule, Routing Width rule, Routing Via Style rule, Routing Layers rule and the Electrical Clearance rule.

Access

The dialog is accessed from the PCB Editor in the following ways:

  • Using any of the commands on the menu associated to the Tools | AutoRoute |  button.
  • Right-clicking over a placed component in the design workspace, and choosing the Component Actions » Fanout Component command from the context menu.

Options/Controls

  • Fanout Pads Without Nets - enable this option to fanout pads from the component, even if they have no nets assigned to them. When this option is disabled, only pads with nets assigned will be fanned out.
  • Fanout Outer 2 Rows of Pads - enable this option to fanout pads from the component, including the outer two rows (which are usually easily routed).
Fanning out a component will drop vias as required to enable connection. If drill-pairs have been configured for layers and the Update fanout using Blind Vias option is enabled, blind vias will be dropped, otherwise, through-hole vias will be used.
  • Include escape routes after fanout completion - enable this option to add escape routing to each fanout. Escape routing places tracks onto the fanout vias and component pads, bringing them out to the edges of the component, to make routing connections to them easier.

BGA Escape Route Options

The option in this region of the dialog only becomes available when the Include escape routes after fanout completion option is enabled.

  • Update fanout using Blind Vias (BGA escape routing only) - enable this option to drop blind vias between configured drill-pair layers in the layer stack. When this option is disabled, only through-hole vias will be dropped, regardless of drill-pair layer settings.
If there are no drill layer pairs defined to be able to use blind vias, this option will appear as Cannot Fanout using Blind Vias (no layer pairs defined).

 

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