There are several ways to check for nitrogen leaks. During pressure testing, raise the pressure to the required level, then wrap the area being tested in plastic sheeting. Then an oxygen sensor can be inserted through a hole in the plastic. If the oxygen level reaches less than 20%, then a leak can be confirmed.
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. ... The IPC preferred term for populated boards is CCA, circuit card assembly.