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Re: Patches, MSVC and bitmap underlays


On Fri, Sep 21, 2012 at 08:28:16PM -0700, Rick Walker wrote:

> To be able to route to the inner pads, I make the outer row purely SMT. 
> Then the next inner row has a 4mil drill but a pad only on the top and
> second layer down.  The next inner layer only has annular rings on top
> and third layer down.  The tracks to the third layer only have to avoid
> the plated drill holes and not an annular ring.  Similiar strategy
> is taken for each succesive ring of pads.  

Via-in-pad requires padstack support, which is not in kicad ATM.

The reason is that a copper pad can only be on a) top b) bottom c) all
the layers. The good news is that the internal data structure actually
supports what you need. The bad news is that it doesn't support antipads
(i.e. on drill only layer the clearance is computed from the hole and
not from the 'missing' pad) but you're actually profiting from this in
your HDI design:D

That could be implemented with not too much work but I'd wait for the
new file format (another score for the bitmapped layer list:P). I think
is mostly a GUI thing to do (also: at the module or board level? what if
the board has another set of layers?)

Lorenzo Marcantonio
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