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<p>
Node: <a name="Design%20Rule%20Checking">Design Rule Checking</a>,
Next: <a rel="next" accesskey="n" href="Trace-Optimizer.html#Trace%20Optimizer">Trace Optimizer</a>,
Previous: <a rel="previous" accesskey="p" href="Rats-Nest.html#Rats%20Nest">Rats Nest</a>,
Up: <a rel="up" accesskey="u" href="Getting-Started.html#Getting%20Started">Getting Started</a>
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<h3 class="section">Design Rule Checking</h3>
<p>After you've finished laying out a board, you may want to check
to be certain that none of your interconnections are too closely
spaced or too tenuously touching to be reliably fabricated. The design
rule checking (DRC) function does this for you. Use the command ":DRC()" (without
the quotes of course) to invoke the checker. If there are no problem areas,
you'll get a message to that effect. If any problem is encountered, you will get
a message about it and the affected traces will be highlighted. One part of the
tracks of concern will be selected, while the other parts of concern will have the
"FindConnection" highlighting. The screen will automatically be centered in the
middle of the object having the "FindConnection" (Green) highlighting. The middle of
the object is also the coordinates reported to be "near" the problem. The actual trouble
region will be somewhere on the boundary of this object. If the two parts are
from different nets then there is some place where they approach each
other closer than the minimum rule. If the parts are from the same net, then
there is place where they are only barely connected. Find that place and connect
them better.
<p>After a DRC error is found and corrected you must run the DRC again because
the search for errors is halted as soon as the first problem is found. Unless you've
been extremely careless there should be no more than a few design rule errors
in your layout. The DRC checker does not check for minimum spacing rules to
copper text, so always be very careful when adding copper text to a layout.
The rules for the DRC are specified in the application resource file. The minimum
spacing value (in mils) is given by the <em>Settings.Bloat</em> value. The default
is 7 mils. The minimum touching overlap (in mils) is given by the
<em>Settings.Shrink</em> value. This value defaults to 5 mils. Check with your
fabrication process people to determine the values that are right for you.
<p>If you want to turn off the highlighting produced by the DRC, perform an
undo (assuming no other changes have been made). To restore the highlighting,
use redo. The redo will restore the highlighting quickly without re-running
the DRC checker.
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