The circuit board 1, wherein said {HEAD ~ halogen compound} is {TAIL ~ at least one compound} selected from the group consisting of YF3, YOF, LaF3 and CaF2 
is
The circuit board 1 , wherein said { HEAD ~ halogen compound } is { TAIL ~ at least one compound } selected from the group consisting of YF3 , YOF , LaF3 and CaF2
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH