kicad-developers team mailing list archive

[jean-pierre charras <jp.charras@xxxxxxxxxx>]

Le 21/09/2012 20:13, Rick Walker a écrit :
> Hi Jean-Pierre,
>
> > a background bitmap is more like the grid that can be shown or not,
> > but cannot be plotted, and is not a layer.  Layers 29, 30 and 31, not
> > yet used in Pcbnew, should be left for something related to the board.
> > A background bitmap is not a board item.
>
> I'm a long-time kicad user and have been championing the use of
> open-source tools (and kicad) at my work.  We are doing very challenging
> layouts for high density systems.  Just about every month the question
> comes up whether we will need to switch to a commercial program such as
> Altium to be able to build the next board.
>
> The hot points have been: buried vias, controlled annular rings on
> BGA pads and two-way interface with mechanical CAD.

Thanks.

Buried vias are supported by Pcbnew, but until now, I do not have any input about this.

Can you tell me more about "controlled annular rings on BGA pads" ?
Pcbnew does not know pad stack, but usually a lot of technical problems can be solved
by using many basic pads having the same pad number to build a complex pad shape.
For instance for a BGA, you can use a SMD "large" pad on the front layer,
and inside it a "small" through pad connecting the inner layers.
This is like a pad stack, with properties defined for one outer layer for the SMD pad
and all inner layers for the through pad.
The testing version of Pcbnew knows 2 pads are connected if the center of a pad is inside an other pad


> I've finessed the annular ring problem by writing a script to generate
> custom .mod files based on a textual representation of the required pad
> stack.  Neither Pcbnew nor the 3d display allows visualization of the
> inner annular rings so we have to plot gerbers to test the output of the
> program.  Messy, but our team is still using kicad...

> kind regards,
> --
> Rick Walker


--
Jean-Pierre CHARRAS