John Doty <j...@noqsi.com> writes: > On Mar 16, 2011, at 4:24 AM, Stephan Boettcher wrote: > >>> Ok. So "via" should be a circle element on "hole" typed layer. >> >> No. A Via is a composit, consisting of a circle on the hole layer, and >> various circles on copper layers, and circles on mask layes, and >> thermals. > > The "layer" concept should be physical, not a metaphysical > abstraction. Objects in a layer may contain holes, but a "hole layer" > is nonsensical, a toxic conceptual shortcut. An "outline" layer is > similarly bad: the insulating layers may all have the same shape > sometimes, but not always.
So, a via needs a separate hole in each copper and insulating layer? And each layer needs its own discription of it's shape? > Trying to model things that aren't layers as if they were layers is > one common mistake in this kind of tool. Equally common is leaving out > layers: the insulating layers in a PCB are just as important as the > copper, and have their own properties (shape, thickness, material, > etc.). They're a critical part of the layer stack. > > The description language needs to be able to express "feature p in > layer x is aligned with feature q in layer y" in order to build up > composites. This is the geometrically sensible way to describe the > result of drilling through several layers. But the geometric > description language should not be tied to any particular fabrication > procedure. This is all too physikal for my taste. Why are you so attached to the concept of drilling? For the design of a layout, all that matters is that there are conductive connections between layers. For me, a layer is something that the designer puts shapes on. Shapes with atributes, if required. The semantics of these shapes on a given layer shall all be the same. Some of these are required for netlisting, some are steering the physical checkout. -- Stephan _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
