Hi,
I’m designing a new PCB with KiCad and I have a problem in setting design rule with Pcbnew. What is the difference between via diameter and via drill? Can someone give me information about it?
Thanks in advance,
Marco
The via diameter is the outer diameter of the copper. (defines the rest copper ring)
The drill is the diameter of the hole.
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Hi, thanks for the answer. So if I have the following requirements
I have to set:
Via Diameter = 0.4 mm
Via Drill= 0.25
Is it right?
Thanks in advance.
Marco
(0.4-0.25)/2=0.075mm anular ring which is smaller than even the 0.15mm anular ring requirement on the thinnest copper option.
You need at least 0.25+2*0.15=0.55.
And also remember that drills have tolerances. If the drill has +/-0.05mm tolerance i would not go below 0.6mm via diameter for a final nominal hole diameter of 0.25mm.
In your case this is all you need to think about. Acourding to your datasheet the anular ring is given as AR = (pad size - final hole size)/2
Some fabs give the anular ring requrements differently and you might even need to think about the difference between final hole diameter and drill diameter.
The drill is a bit larger than the final hole. (my fab told me they drill with +0.1mm.)
If this would be the case this would mean you need 0.7mm minimum via diameter.
But again this really depends on your fab.
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