The Effect of Adventitious Oxygen on Nitrogen Inerted IR Reflow Soldering with Low Residue Pastes Available to Purchase

The benefits of Nitraclean I nitrogen inerted reflow soldering are well documented. However, there has been some debate as to the maximum oxygen level that can be tolerated by different types of paste if those benefits are to be realised. It is demonstrated that, for all paste types, solder balls decrease and the spread factor increases with increasing oxygen level, but that it has little effect on either joint strength or microstructure. It is concluded that for RMApastes a maximum oxygen level of 1000 ppm is required and that for low residue pastes the level needs to be reduced to 200 ppm for optimum results.