soldermask on mounting holes
Main and power backplanes have some of the mounting holes covered with solder mask only on one PCB side. In fact the soldermask should still have an opening of the hole size. Otherwise soldermask will flow into it.
Main and power backplanes have some of the mounting holes covered with solder mask only on one PCB side. In fact the soldermask should still have an opening of the hole size. Otherwise soldermask will flow into it.