On round soldered pads, I've had the mask come loose between two pads, and then solder got under it and bridged the pads. I haven't had any issues with thin mask webs between unsoldered pads. Someone with more experience in the actual soldermask printing process may be able to illuminate this further- I'm not sure whether there are equipment limitations that may cause issues. That said, I do typically avoid thin webs between unsoldered pads in my designs, sometimes by partly covering the via pad with the soldermask (creating something that looks a bit like a mask defined pad). Tom On Tue, Feb 19, 2019 at 10:57 AM Jack Olson <[log in to unmask]> wrote: > In my experience, what a PCB fabricator would consider a sliver would be > the strip of soldermask material between RECTANGULAR pads being less than a > minimum width. > We got a "DFM report" for a board where minimum distance between ROUND vias > is being reported as slivers.Has anyone ever heard of problems with minimum > mask material between round, unsoldered vias? > I can't imagine any real-world problems that could cause, but I have an > open mind... >