Re: gEDA-user: Preliminary report on gerbers with buried, hiddenand

[Ales Hvezda <ahvezda@xxxxxxxxxxxxxx>]

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-- Cut here --
From: Mike Jarabek <mike_jarabek@xxxxxxxxxxx>

Hi all,

    It looks to me like the options for these blind and buried vias are
quite varied.  What about the folllowing:

        1) Instead of forcing anyone into a particular arbitrary set of
layers, simply have the data structure for the Via have a `start' and
`stop' layer.  (AFAIK, vias always start and stop on a well defined
layer. ;-)
        2) Write a proper DRC that can read a technology file that
spells out which start/stop combinations are valid.
        3) Ensure that the Autorouter is aware of the technology file,
so it does not create illegal vias when changing layers.
        4) Have the CNC output routines emit a CNC file for each pair of
start/stop layers it finds.

    Additionally:

        1) The technology file is optional, you don't have to use it
unless you want to.
        2) The program automatically figures out which combinations have
been used and spits out the appropritate files.
        3) Ensure that vias can be placed one on top of the other.  Eg,
a via on from layer 1 to 2 and from 7 to 8 should be legal, as they
don't connect
        4) Perhaps we need some kind of via editor, where things such as
start/stop layer and when pad landing flashes should be made in the
Gerbers, or perhaps to treat a via a little more like a component, eg.
like a library element.

Sound reasonable?

Mike

DJ Delorie wrote:

> A little googling found one fab house that did it differently :-P
>
> +============]  [===]  [===  \
> |            ]  [   ]  [===   > panel 1
> +============]  [===]  [===  /
>                     ]  [     <-- blank
> +============]  [===]  [===  \
> |            ]  [   ]  [===   > panel 2
> +============]  [===]  [===  /
>
> Then you can glue two of these together to make 8 layer boards.
>
> Yet another etched matching copper on adjacent panels (i.e. as above
> but no blank, resulting in 3 copper layers) and allowed vias between
> any adjacent copper layers.
>
> Sigh.