User Guide

7.12 PracticalTips
This section presents you with some tips that have, over a period of
time,beenfoundusefulwhenworkingwiththeAutorouter.
Look on these examples as signposts suggesting ways in which a board
canberouted.Noneofthesesuggestionsguaranteesuccess.
General
The layer costs (cfLayer) should increase from the outer to the inner
layers or be the same for all layers. It is unfavorable to use lower values
in the inner layers than in the outer layers. This could increase the nee
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dedroutingmemoryenormously.
Single-SidedBoards
Therearetwoprocedures,dependingonthekindoflayout:
In the simplest case, only layer 16, Bottom, is active. No preferred direc
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tionisdefined.SelectasuitablegridandruntheAutorouter.
If the layout is rather more complex, it may be possible to achieve a us-
able result with special parameter settings. Please take a look at the pro
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ject named singlesided, which can be found in the eagle/projects/examples
directory. This example project comes with various control files (*.ctl),
which areoptimizedforsinglesidedrouting.
The Autorouter may use the Top layer as well. The tracks laid there will
be realized as wire bridges on the board. In layer 41, tRestrict, you can
define restricted areas around the components and in regions where
wirebridgesarenotallowed.
Feelfreetoexperimentwiththeparametersettingsforyourlayout.
SMDBoardsWithSupplyLayers
Thefollowingprocedurehasbeenfoundeffective:
The supply signals are routed first. In general, a short track is wanted
fromaSMDcomponenttoaviathatconnectstotheinnerlayer.
Before altering the parameters, save the current (default) values in an
Autorouter control file (CTL file). Click on the button Save as.. in the
General tab of the Autorouter setup window and input any name, for
example, standard.ctl.
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EAGLEManual