gEDA-user: how to layout conductive ink traces

[John Griessen <john@xxxxxxxxxxxxxx>]

I have found a fab for conductive ink over paint like insulating ink
and am trying to figure out the best way to use pcb as is to get results.

A pseudo-via for conductive ink needs two different sizes of pads, a smaller one in top copper,
then a larger one in conductive-ink layer.  Then the insulating layer needs a slight keepaway
distance from the copper circle, and it need only be between vias and not surround them.

One way would be to just use vias and other layers, then post process to fill the
copper of via holes and also take away the drill hole from the drill list, then add
the insulator as another layer.

I can't find a setting for min via size, even though pcb won't let me set it to zero
even with an action command...  where is the equivalent of the Pcb file now?  ~/.pcb/preferences?

Another way would be to create footprints with several lengths and widths
to use for jumping a few copper traces, which is a pretty close match to how you use
conductive ink most of the time.  It complicates your life though, for handling
the 40 milli-Ohms per square resistivity of silver based ink.  There's not
much need of it in the schematic, except if you were doing simulations and lumped
parameter sims is all I can imagine coming from the schematic anyway.
On the plus side, footprints or pcb "layout data in a buffer" will let you reuse
checked work and avoid errors on something that is a tricky DRC to do -- we don't
have enough in place for
DRC checking that you have insulator "nearby" yet not touching -- do we?

How would you write a DRC to: "Require insulator with a grown overlap anywhere top-copper and
conductive ink layers overlap"?

And, "Can we put other than silk and pads in a footprint?"  No, I think.

For conductive ink pseudo-footprints that must include traces and insulator layer to be
useful, I am planning on making layout files of just the required parts so I can load them to a buffer.
That would avoid a schematic entry for them too.  That may be all there is to it, but any ideas
would be appreciated.

John Griessen

-- 
Ecosensory   Austin TX


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