pi9 wrote: ↑
Tue Jul 16, 2019 2:44 am
I am surprised quality control wouldn't catch something like this. I never saw this in any of the board I buy from China
Nonsense, its a common occurrence if you make multiple rectangular PCB's in an array from a large plate, and then separate the PCB's from each other with a V-cut (groove).
The board from China you saw were probably one-off's, non rectangular edge milled. Not mass produced rectangular boards.
most often the V-cut cleanly separates the boards, but as glass fiber boards are made from fiber, (duh) sometimes if the cut is happening along the fiber thread, as it would. then single threads might break off along the break edge.
Its purely an aesthetic issue, and the product is too low cost to manually clean the edges of the boards, so quality control ignores this as a non-issue.