Two effects of N2 system reduce soldering defects.
N2 System mechanism
Nitroge gas is heated inside soldering iron and is exhausted from the tip end of soldering iron. It effects preheating P.W.B. and reduces soldering defects.
The following page offers the illustrated structure of N2 system and the temperature of heated nitrogen gas
N2 soldering iron varies depending on your HAKKO soldering station.
The combination examples lead you to the required equipments and the related products.