kicad-developers team mailing list archive

[Jean-Paul Louis <louijp@xxxxxxxxx>]

Hi Rick,

You’re quoting me for something I didn’t write, I think it was Tom.

	I think our development team could find a way to handle this by having a via created with only a TOP and BOTTOM pad, and then during the routing, create a inner pad only on the layer where the trace continue. This could be an added attribute of the via, like a list of layers where the via barrel has an annular ring. The default list would have only Top or F.Cu and Bot or B.Cu, whatever is agreed upon.

	Pin escapes on large BGA are always a challenge as the annular ring take a lot of the real estate. Same thing with decoupling caps on those BGAs. There is not much room to place the caps real close to the point where it is really needed.

Jean-Piere and the core team will decide what is best. I can just watch and procrastinate as I am not good enough yet to offer code snippets to address such issues.

Jean-Paul
AC9GH


On Jun 5, 2014, at 3:34 PM, Rick Walker <walker@xxxxxxxxxxxxxx> wrote:

> 
>> On 05.06.2014 02:48, Jean-Paul Louis wrote:
>> 
>> I don't think it's possible for the moment. Defining custom via/pad 
>> stacks is a quite big work package in itself and IMHO can be decoupled 
>> from the layer extension WP. I'm not even sure if one can define a via 
>> without antipads on internal layers (Lorenzo?)
> 
> Yes it is possible.  The footprint definition has a long int mask which
> specifies the existance of a pad ring on each layer.  There is no GUI
> support.  I had to write an awk script to generate my BGA footprints
> textually, setting the hex value inside my generated footprint file. 
> 
> The design was tedious to do made it through fab just fine.
> There was no other way to get the internal signals out of the
> high density BGA footprint except by leaving off internal annular
> rings on some layers.
> 
> --
> Rick Walker
> 
> 
> 
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