User Guide

Thecommandcorrespondingtothisexamplewouldbe:
LAYER2$GND
This specifies that layer number 2 (previously known as Route2)is
henceforth known as $GND, and that it will be treated as a power sup
-
plylayer.
Supplylayersaredisplayedandplotted inversely
!
Pads are connected to power supply layers with what are known as ther
-
mal symbols, or are isolated with annulus symbols. Thermal symbols
usually just have four thin bridges as a conductive connection to the
through-plated hole. They are used because the high thermal conduc
-
tion of a continuous copper plane would result in the pad being no
longer solderable. The shape and size of the annulus and thermal sym
-
bolsarespecifiedintheDesignRules(DRCcommand, Supply tab).
To keep the board edges free of copper draw an isolating wire around
the layout. This avoids possible short circuits between adjacent (supply)
layers. If you want to use the Autorouter, however, these wires must not
be drawn until the routing process has been finished. Automatically
generatedsupplylayershavetobedisabledintheAutoroutersetup.
No additional signals or signal polygons may be drawn in these layers. That
wouldleadinevitablytoanunusablecircuitboard!
Detailson SupplyLayersand Autorouter:
The Autorouter takes into account all inner layers, and so delivers the
full set of patterns for multilayer boards. It connects SMD pads to inner
layerswithvias.
Assumed only vias that can connect all layers (from layer 1 to 16) are
used (through vias), the preferred direction for the Autorouter has to be
set to N/A for power supply layers (this means the layer is not available
for routing). This is only possible for layers that do not contain any
wires.
If you are using, among vias through all layers, blind, buried, or micro
vias the Autorouter can't work with supply layers. In that case you have
tochangethesupplylayerintoaninnerlayerwithpolygon:
Therefore deselect the Supply flag in the Change window of the
DISPLAY menu and draw a polygon in the inner layer. The polygon has
tobegiventhenameofthesupplysignal.
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FromSchematictoFinishedBoard