| ID: | 3920 |
| From: | Hannu Vuolasaho <vu...@msn.com> |
| Date: | Sat, 4 Apr 2020 12:34:31 +0300 |
| Subject: | Re: [pcb-rnd] drc: Keep board readable warning breaking silk |
| in-reply-to: | 3898 from ge...@igor2.repo.hu |
On 2.4.2020 18.10, gedau@igor2.repo.hu wrote: > > On Thu, 2 Apr 2020, Hannu Vuolasaho wrote: > >> Hello! >> >> One feature which helps to detect visual problems with boards is to have error >> on solder mask opening and silk. If this happens, the refdes for example is >> cut. Holes also break silk > Thanks, nice one! > > Please think over if the following formal definition would work properly > on positive and negative cases: > > "Violation is where a silk object (geometrically) intersects a mask > object". (Assuming the mask shape of a padstack is treated as a mask > object for this definition.) This is something like Eagle does and I've found it very good indicator of not thoroughly thought design. I also think this definition went straight to the target. > If that works, trivial extensions to similar cases: > > - silk vs. paste Paste is on soldermasked area or silk is on exposed part of soldermask. This is redundant if other checks are also enabled > - paste vs. mask You don't want to put paste over soldermask. Someone forgot to make mask opening in padstack :) > > - paste vs. copper (you never want to put paste on the bare FR4!) These good extensions And mask vs copper which is not so easy but I'll think about it for completeness sake. Normally you don't want to expose bare FR4, as it is UV and moisture sensitive. UV makes board brittle and moisture inside the board will ruin reflow soldering. However for example LFGA package needs soldermask removing undeneath as the pins are above the bottom plane while QFN has pins below bottom plane. Outside those packages look identical, but there is a difference. I don't recommend at least as default rule mask vs. copper rule. Just for a reminder opening soldermask and exposing (gold plated) copper can be used in pcb artwork. Vuokko
Reply subtree:
3920 Re: [pcb-rnd] drc: Keep board readable warning breaking silk from Hannu Vuolasaho <vu...@msn.com>