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Chapter 7
Autorouting and Autoplacement
Caution
The Default button sets default values for all tabs in the Routing Options dialog
box.
NI Ultiboard User Manual
•
Pin Contact Mode—Select Allow Pin Corners to allow traces to
connect to pins diagonally.
•
Place Vias Under SMD Pads—Select Yes or No as desired.
•
Auto Adjust Trace Width checkbox—Enable to allow the router
to narrow the trace to its minimum width as set in the Nets tab of
the Spreadsheet View or the Width tab of the Net edit dialog box.
•
Fanout BGA Parts checkbox—Attaches vias to each pin of all
BGA (Ball Grid Array) parts. If the DRC checkbox is enabled, a
design rules check is performed before fanouts are placed. In cases
where attaching a via to a specific pin would violate a design rule,
the via is not attached. This does not affect the attachment of vias
to pins where there is no design rule violation. Refer to the
Rules Tab
section of Chapter 1,
about design rules.
•
Use Pin/Gate Swap checkbox—Enable to allow pin/gate
swapping while routing to swap equivalent pins/gates to result in
more optimal trace connections.
4.
In the Screen Refresh During Routing area, adjust the slider as
desired to set the relative number of times the screen is refreshed
during routing.
5.
If you wish to return the values to the default settings for Ultiboard,
click Default.
Routing Options: Cost Factors Tab
You may adjust cost factor settings to control how the router "costs" its
various routing strategies.
The default values are chosen carefully to give you the best balance of
routing characteristics, except in exceptional circumstances. In general,
leave the cost factors at their default values unless the autorouter is not
producing the results you want. Any adjustments that are not carefully
considered can actually worsen autorouter performance.
Therefore, if you decide to change cost factors, adjust no more than two
cost factor variables at a time and make your changes in small increments.
Large adjustments to many variables will almost certainly cause poor
results. Also remember that many variables share strong mutual
dependencies. For example, any increase in via placing costs compromises
the router's ability to route using preferred directions.
User
7-12
Design
Interface, for information
ni.com
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