How does one remove non-functional pads in vias?

On 12/04/2015 2:33 a.m., Bruce Mellen wrote:

How does one remove non-functional pads in vias?  I’m not finding the

requisite check box(es) or other settings.

I need to minimize the discontinuities in at least the higher frequency

paths, want to somewhat shrink the resulting anti-pads on the ground and

supply layers to improve current return impedance, and it can often

contribute to better routing in the vicinity of vias.

I was hoping to even set it by layer and perhaps set the restring by

layer, having it depend upon whether there is a trace connected or not.

The only alternative seems labor-crazy intensive, effectively:

• Setting normal via restring values and applying the appropriate

teardrops to the various layers

• Minimize the restring values to the smallest NFP values wanted for the

board, and

• apply a circle to each and every capture pad where there is a trace to

be connected

• subsequently approving the circle overlap DRC errors

Please describe a better way…?

 

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So you mean " How does one remove the unused restrings from the inner

layers"

This is all about 'pad stacks' and the ability to specify the restring

by layer or even pad/via. Historically this feature was requested many

times and has not been delivered by Cadsoft. Jorge did mention recently

that they were working on keep-outs for the inner layers so perhaps that

implies pad stacks are coming. As an aside; I note that many of the

power users who were vocal about their need for pad stacks either are

known to have moved away from eagle or are not heard from very often

these days suggesting they have voted with their feet.

You may care to investigate the following ideas:

(1) Edit/delete these unwanted restrings in your Gerber editor.

(2) Don't place the circle, that you subsequently have to approve in the

DRC, on the signal layer but rather on a user defined non signal layers

and merge the signal and non signal layer when you generate the Gerber

for that copper/signal layer.

(3) Create a ULP to automate the 'labor-crazy' part. Again, start as you

have with minimised inner restrings. Use the ULP to locate the inner

restrings that have traces connected. The ULP then adds a polygon

(circle) over that restring of the required size. The polygon is given

the same signal name as the trace so there are no DRC errors.

HTH

Warren

Warren,

Thanks for the potential workarounds; I understand what you are describing.  My knowledge of ULP and the data structures, however, is non-existent. 

It appears that the product is not quite ready to do the serious work I was hoping to occasionally do.

You gave me an idea….. What might be an even better workaround might be: for the person that does the teardropsc URL (helpful in preventing breakout with drill wander and providing a more secure connection to vias), to also include an arc (of the same signal) that mostly surrounds the hole, with each end of the arc at the teardrop intersections with the capture pad.  After teardropsc is run as one of the last steps before generating Gerbers, the inner restring value can then be minimized.  The snippet below shows what might result in an inner layer – being just my curved trace, two short traces, and three arcs, to cover the area that needs to be occupied by the normal restring capture pad.  The via hole is the circle in the center.

Warren,

Thanks for the potential workarounds; I understand what you are describing.  My knowledge of ULP and the data structures, however, is non-existent. 

It appears that the product is not quite ready to do the serious work I was hoping to occasionally do.

You gave me an idea….. What might be an even better workaround might be: for the person that does the teardropsc URL (helpful in preventing breakout with drill wander and providing a more secure connection to vias), to also include an arc (of the same signal) that mostly surrounds the hole, with each end of the arc at the teardrop intersections with the capture pad.  After teardropsc is run as one of the last steps before generating Gerbers, the inner restring value can then be minimized.  The snippet below shows what might result in an inner layer – being just my curved trace, two short traces, and three arcs, to cover the area that needs to be occupied by the normal restring capture pad.  The via hole is the circle in the center.