User Guide

Any other data format can be created with the aid of ULPs (User Lan
-
guage programs). See the short description of ULPs in the Control
Panel.
6.4 MultilayerBoards
You can develop multilayer boards with EAGLE. To do this, you use
one or more inner layers (Route2 to Route15) as well as the layers To p
and Bottom for the top and undersides. You display these layers when
routing.
Before starting the routing of the layout you should be aware of the
number of signal layers to use, if vias should go through all layers, or if
you have, due to the complexity of the layout, to work with blind, bur
-
ied or micro vias. In this case you realy ought to contact your board
-
house to inform you about the possible structure of the board and the
resultingcoststobeexpected.
Also think about how to use the inner layers: As a normal inner signal
layer or as a supply layer? On this, for example, depend reasonable via
lengthsthathavetobedefinedintheLayersetup.
InnerLayer
Inner layers are used the same way as the outer layers To p and Bottom.
They can be filled with copper areas (polygons) as well. A special status
havetheso-calledsupplylayerswhicharegeneratedautomatically.
Before using inner layers you must define them in the Design Rules,
Layers-Tab. More details can be found in the following sections and on
page 100.
SignalLayers
You use the ROUTE command as usual to place tracks in those inner
layers which are provided for signals. Eagle will itself ensure that the
tracks are connected by way of plated-through holes to the appropriate
signals in the outer layers. The settings of the Layer setup in the Design
Rulesapplyforthisprocedure.
SupplyLayerswithPolygonesandMorethanOneSignal
Areas of the board can be filled with a particular signal (e.g. ground) us
-
ing the POLYGON command. The associated pads are then automati
-
cally connected using thermal symbols. The isolate value for the thermal
symbols is specified in the Design Rules (DRC command, Supply tab).
The width of the connecting bridge depends on the line thickness with
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FromSchematictoFinishedBoard