Chapter 7
Autorouting and Autoplacement
7-12
ni.com
•
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
, for information
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
.
Caution
The
Default
button sets default values for all tabs in the
Routing Options
dialog
box.
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.
