Hello, I wanted to comment on Joe’s post.
Joe is talking about “solder mask sliver” as most manufacturers call it. It is the small hairs of solder mask that will be left e. g. between IC pads when the solder mask is expanded so it is slightly larger than the pads. This solder mask sliver has a minimum value of ~100um for most manufacturers. If the sliver is <100um, it is too small to be manufactured reliably, forcing them to remove it. It means that there is no solder mask between the pads. The solder paste flows uncontrolled and may short the pads.
On one of my boards the manufacturer came back and warned me about this, wanting to make the pads smaller so the minimum sliver could be maintained.
This was embarrassing as I should have found it myself during DRC. I started searching in the DRC, but I could not find any way of checking for minimum sliver: File/Board Setup…/Design Rules/Solder Mask/Paste
It appears to me that KiCad has no way to check for minimum solder mask sliver. Does anyone know how to check it?