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Re: Patches, MSVC and bitmap underlays


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.


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

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