pcb-rnd knowledge pool


Layer terminology

term_layers by Tibor 'Igor2' Palinkas on 2017-01-05

Tags: spec, layer, group, terminology

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Abstract: Specify the terminology of layers.

  The exact specification of the layer model can be found in the user manual. The table below is an extract of the most commonly used terms.

term description
layer logical layer, canvas; may be positive (==additive) or negative (==subtractive); negative not supported on copper
layer group physical layer of the board; a group hosts an ordered list of layers
auto layer side effects (automatic drawings) from elements, subcircuits, etc. will use this layer
layer group type material/purpose of the layer group (e.g. copper, mask, silk, substrate)
layer type
substrate layer group type; does not host layers; any insultion layer
top layer group at the natural/default orientation of the board, the given layer group of the given type is an outer group and is on top or bottom; e.g. top silk group, bottom copper group
bottom layer group
internal layer group any layer group that is in between top and bottom layer groups
global layer group the group affects all physical layers, e.g. the outline layer that cuts through the whole board
layer stack the ordered list, from top to bottom, of layer groups
layer object an object (e.g. line, polygon) that is on a specific layer
global object an object (e.g. a padstack or a subcircuit) that is on the board, but is not limited to one layer or one layer group
cross section view GUI feature that shows a cross section of the board, typically to describe the layer stack

Note: we used to use terminology "component" and "solder" side. We stopped using those terms because they do not make sense on modern SMD or even mixed boards where both sides may host SMD and/or through-hole components.