Black marks on PCBs

[glx]

Hi,

Just a question out of curiosity. I noticed that the edge of my boron’s PCB looked a bit “ununiform”, so I observed it a bit closer and I realised that it’s a mark from a black pen. Is it some kind of “quality chack passed” mark or something? I couldn’t find anything on the forums or the docs …
Really nothing that bothers me (besides the fact that I didn’t notice that until now , and I found them now on every board ) but I’m curious anyway what they are for .

[marekparticle]

Hi @glx! This just indicates that routine testing was done on the device, nothing more. (I also didn’t know this, and was always curious, so I’m happy to have learned the answer myself!)