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Re: How do we envision Pad Stacks?


I thought at one time we had an initial proposal document written for
pad stacks but I cannot seem to find it.  I thought it was either Orson
or Tom who wrote it but maybe I'm remembering this wrong.  If not, we
need to create one to make sure we have it well defined before any
implementation can be done.

I think most EDA pad stack editors allow for different shapes per layer
so we should probably follow suite.  I would think a pad stack would be
used for allowing SMD pads to be placed on inner layers although I have
not idea how this is handled by other EDAs.

On 6/11/20 10:54 AM, Jeff Young wrote:
> I had been assuming that you could define a separate shape for each
> layer.  Full flexibility, but time-consuming to edit (even with commands
> such as “push current layer to other layers”).
> Most users are looking to route traces on inner layers between tight
> pads.  This is commonly done with the definition of a “capture pad”.
>  The constraint on inner layers that have connecting tracks is simply
> not to have a butt joint between the track and the plated hole.  A
> capture pad is therefore a circular pad with an annulus width of the
> drill wander plus 1 or 2 mils; other capture pad shapes get you nothing
> more.
> There were also a few requests for SMD pads on a single inner layer (or
> perhaps multiple) — but importantly not for different shapes on
> different layers.
> So one could imagine allowing the pad shape to be placed on any number
> of layers, and a capture annulus width for any other connected layers.
>  While it doesn’t have same flexibility, it would be a /lot/ easier to edit.
> Another possible complication is wanting a different shape for mask (or
> paste) layers.  Is this ever required?
> Thoughts?
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