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[SOLVED] CADSTAR. Define a via with no annular ring?

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Member level 1
Nov 29, 2012
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I'm using a lot of stitch vias in my design. They connect ground planes.

The via I use doesn't have any any annular ring only a drill hole. So when it gets plated it connects the ground planes together.

I have defined the via circle size the same as the drill diameter.

But should I set the circle size to zero?

If it will always be within copper then its not going to be a problem, however what about when it's not?
For it to be plated it "must" have an amount of copper for the plating.

So why not just give it the minimum needed for annular ring.

That way if you use it to join a piece of coper on the top to the plane then you do not have to worry about there being copper on the bottom.

In simple terms, vias without an annular ring according to the respective board technology design rules are not guaranteed to be plated at all. In the usual through-plating process, they'll be possibly partly or completely covered with photo mask before the galvanical plating takes place.

If used exclusivly in copper you will have no problem either way, but best to have annular ring same size as drill size, so they are visible on screen in certain situations, thats what i quite often do with stiching/thermal vias.

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