More high-density interconnect (HDI) improvements including the tuning of the auto-router (Allegro PCB Router - SPECCTRA) to use the via patterns, alignment of via list priority with Allegro PCB Editor, and creation and removal of anti-acid bars are available in the 16.5 release of the Allegro PCB Router.
Read on for more details…
In this release, the SPECCTRA auto-router provides the ability to use inset/tangency and stagger via patterns.
Autorouting with Via Patterns
The auto-router takes into consideration effective inset/tangency rules to find the most optimal 3D path. Usage of via patterns is regulated by via and via pattern costs.
Ordered Via Lists
In Allegro PCB Editor, the via lists were prioritized, but prior to the 16.5 release, the Allegro PCB Router did not have this capability. The 16.5 release now provides this ability.
This command will turn on/off the prioritization of the via list provided by Allegro.
set follow_usevia_priority on/off
Note: It is best to set this switch to on ONLY when working with HDI structures. When using standard PCB structures it is preferred to NOT set this switch.
To avoid the acid traps at tangent/inset bbvias/microvias, Allegro PCB Router allows the creation of anti acid bars. These are rectangular bars created on each layer to avoid the acid traps.
The anti-acid bars are created by using the following command:
This command may be used to remove the anti-acid bars
The Allegro PCB Router constructs an anti-acid bar for each pair of tangent/inset bbvias as a path on a shared layer with the valid width values:
I welcome your feedback on these new 16.5 capabilities.
Jerry “GenPart” Grzenia