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how to create a very small circular shape

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Newbie level 3
Sep 18, 2009
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Hi to all,

I'm making a very special PCB board (USING CADENCE ALLEGRO PCB) in which I have rectangular pads of 20 um x 20 um. what is special with that board is that its substrate will be made by glass and it has just one metal layer. Now I have to design a circular shapes of 25 um as a diameter in order to superpose them exactly on the pads that I have, those circular shapes will be used later in a flip chip processing.

I was not able to make those circles, Allegro do not allow me to design such small ones :-(

Does any one has a an idea please


Did you try this in Pad Editor of Allegro? Because I just tried it and can make 25uM circular pad no problem.


Look in setup and You might wanna select millimetre instead of mills and then choose 4 digits as accuracy.

Hi majnoun,

Yes I know that, what i wanna do is not to have a circle pad, if not is to make a full circle shape with 25 um diameter :)

this circle shape will be put it on the rectangular pad..

thanks for everything

Added after 9 minutes:

Hi Lhademmor,

I tryed it, now i'm just able to make a circle with the dimentions i want using the menu: Add > Circle

But using this way I can just make a normal circle as a solid and not a shape. In that option I can fix the line width of the circle.

In the other case, when I try to do this: Shape > circle

I can choose which Fill type I want and to which net name i will assign that shape. But i doesn't allow me to fix the line width :|

anyway, thanks for everything guys

IfI find it i will let you know ;)


Line width for a shape ? A shape has an edge but if You wanna do a circle shape with crosses the do the circle shape, select it right click choose parametres and change settings.

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