The PCB 1 wherein {HEAD ~ the metal} having {TAIL ~ a conductivity} lower than the conductivity of copper is nickel 
The PCB 1 wherein { HEAD ~ the metal } having { TAIL ~ a conductivity } lower than the conductivity of copper is nickel
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH