Adding nitrogen to SMT reflow furnace

Selective wave soldering nitrogen filling welding usually adopts the gas dispersion technology, which means that the solder is sprayed into the solder wave required by the design through the electric pump or electromagnetic pump, and the nitrogen is evenly diffused on the wave crest surface by injecting nitrogen into the solder pool, so as to achieve the purpose of inert gas protection.
The main function of adding nitrogen (N2) to SMT reflow furnace is to reduce the oxidation of welding surface and improve the wettability of welding. Because nitrogen is an inert gas, it is not easy to produce compounds with metals. It can also isolate the oxygen in the air from the metal at high temperature and accelerate the generation of oxidation reaction.
The principle that the use of nitrogen can improve the solderability of SMT is based on that the surface tension of solder in nitrogen environment will be less than that exposed to the atmospheric environment, so that the fluidity and wettability of solder can be improved. Secondly, nitrogen reduces the solubility of oxygen in the original air and substances that can pollute the welding surface, greatly reducing the oxidation effect during high-temperature soldering, especially in improving the quality of second side reflow.