Cooper drilling question


Hi Folks

I’m a newbie with a few successful home-etched boards under my belt, but have a question about drilling with respect to copper placement.

For reasons I don’t understand, sometimes my top and bottom copper etching layers have wires terminated in ‘solid blobs’ and other times in ‘hollow blobs’. I can see any relevant properties of wires or components to change how they appear.

This makes it hard when drilling the holes. Drilling through ‘hollow blobs’ is easy, but through ‘solid blobs’ is hard and the drill moves around.

I’ve attached a picture of part of my board and the corresponding bottom copper layer.

Thanks experts!

drilling questionmark4.fzz (26.9 KB)


It looks like your problem is that you have extended the trace too far. It is possible (although somewhat difficult) to terminate the trace on the far edge of the pad rather than the near edge. If you do that the copper will extend across what should be the hole. If you zoom in on the pad you should see that. I usually have to delete the trace and rerun it (if I care, I rarely make boards but tend to do this when checking parts where I don’t care if the copper is messed up :slight_smile: ). I actually had to work at breaking this example, but experience tells me it is easy to do on on a multipin part. The top left pad in this is incorrect and will render as yours does without a hole in the middle.




Although I agree with what @Vanepp said it actually looks like an issue with the math used for the connection of curved traces. As soon as you curve a trace it connects past the center hole.

This subject has come up before for different reasons and manufacturing houses would like the paths to end in a solid blob and home etchers want the hollow blob. The only solution I can think of is to export as an SVG and then use something like Inkscape to do a difference of drill SVG from the Copper SVG.


I guess another solution would be to not use curved traces and only use 45 degree corners.


Hi. Yes, tests confirm, if I stick to 45 degree lines then it always terminates with hollow blobs.



More testing. It’s any curve which leads to the solid blob. Any angle straight line results in a hollow blob.

Thanks again everyone