kicad-developers team mailing list archive

[Andrew Zonenberg <azonenberg@xxxxxxxxxxxxxxx>]

As of now KiCAD uses a 16-bit bitfield for layers although work is
apparently underway to fix this.

Your request for a stackup file should probably be merged with
https://bugs.launchpad.net/kicad/+bug/961533.

I filed the ticket a long time ago and got too busy with school stuff to
implement it.

On Wed, 2014-06-04 at 20:48 -0400, Jean-Paul Louis wrote:
> Lorenzo and all,
> 
> I see in your last very descriptive email, that the number of copper layers seems to be limited to 16.
> 
> Does that mean that my 20 layers backplane will have to use 4 custom layers that really will be copper.
> Will the routing of those custom layers be even possible? How pcbnew will treat those 4 new layers? Will I be able to have vias that connect to those layers?
> 
> High speed digital systems routinely have backplanes with 20 or more layers, and a thickness varying from 3.2mm to 6.35mm. And due to the need for impedance controlled layers, there are quite a few power layers to generate strip-lines, and other distributed constant lines, so vias with thermal relief are also needed with a way to edit the way the thermal relief is done (signal versus high current). I have not found a way to create thermal relief in vias. Is it described somewhere?
> 
> Could we use a PCB stack-up file that would define a set of attributes for each layer. The attributes would be a Layer ID, Layer Type, Layer Position in the stack, Usage that would let us know is it is a physical layer (Board blank, Copper, Solder Mask, Solder Paste screen, Silk Screen, etc..), or a documentation layer (Assembly drawing, BOM, ECO1-N, etc..).
> 
> It might be too late now, as you might have good reasons for not changing (too much code relying on existing stack-up), but that would definitely increase the strength of KiCad.
> 
> Jean-Paul
> AC9GH
> 
> 
> On Jun 4, 2014, at 6:06 PM, Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx> wrote:
> 
> > On Wed, Jun 04, 2014 at 05:29:48PM -0400, Jean-Paul Louis wrote:
> >> Edge.Cut was not an obvious candidate for me, but I can live with that name, but I think it should one of the mandatory layers, not a user defined one. Every PCB will need an outline, and circles and arcs would be nice if allowed in outlines.
> > 
> > It's *extremely* mandatory and it has a lot of special cases, don't
> > worry about that... arcs are allowed in outlines (however you can only
> > draw arcs of 90 degrees, now...)
> > 
> >> About the height of the parts, I agree with Tom that this should be a field in the Footprint itself, as that’s where the physical info (dimensions) of the part (pads, holes) is/can be stored. Height of the part is very important for placement machines, and is used to define the sequence of parts, i.e. the tallest parts are placed last. Usually not an issue with chip shooters, but down the line, it is critical for the IC and Odd Shape placer/inserter.
> > 
> > I think is better to use the IDF info (or, conversely, use that value to
> > build a 'default' IDF from the assembly drawing). And anyway these are
> > problems appearing looong way after the layout process, I don't think we
> > should care. Machine operators know better than you and me. And have
> > very expensive software provided with the very expensive machine to do
> > these consideration.
> > 
> > Otherwise the first thing you'll have to do is to sort the drill tape
> > for minimum travel...without knowing how the mill is tooled, of course.
> > 
> > 
> > -- 
> > Lorenzo Marcantonio
> > Logos Srl
> > 
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-- 
Andrew Zonenberg
PhD student, security group
Computer Science Department
Rensselaer Polytechnic Institute
http://colossus.cs.rpi.edu/~azonenberg/

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