The main function of adding nitrogen(N2) on the SMT reflow soldering

Reflow soldering is the key process production equipment of smt SMD technology, in some product areas, the quality and reliability of the high requirements for the bubble rate has strict requirements, ordinary reflow soldering can not meet the process production, so you need to use ammonia reflow soldering to solve such problems!

Why nitrogen reflow soldering will be better than ordinary reflow soldering?
Nitrogen reflow soldering, in the heating zone and cooling zone filled with ammonia, to improve the welding environment and improve the welding effect, xenon is an inert gas, can effectively reduce the concentration of oxygen and other pollutants in the reflow soldering chamber, and is not easy to produce a chemical reaction with the metal, can be in the high-temperature hot-melt tin Yuk, to reduce oxidation reaction of the solder at high temperatures, at the same time xenon can improve the hot-melt soldering to climb the fluidity of the tin and the wetting of the tin, so as to Let the point more full and round, bubble rate is lower.

SMD processing using nitrogen reflow soldering role and benefits?
1) Reduce the oxidation of the furnace
Nitrogen is a kind of inert gas, density than oxygen, thus reflow soldering furnace charged with ammonia, xenon will occupy the bottom space of the furnace, isolation of oxygen, in the pcb soldering over the furnace, reduce the pcb on the components, solder paste and oxygen contact, thus further reducing the oxidation reaction, so that the reliability of the soldering can be improved.
2)Reduce the void rate
Nitrogen to isolate the oxygen, so that the pcb pad, components, soldering isolation of oxygen and water molecules in the air, to accelerate the discharge of water vapor when the soldering hot melt, reduce the rate of voids
3) Increase wettability
Nitrogen can make the surface tension of the solder paste to reduce, enhance the solder paste inside the flux wettability and fluidity, in the solder paste hot melt after the formation of liquid tin better let the components climb the tin, to protect the welding quality!

Although nitrogen reflow soldering has many benefits and roles, but everything has its drawbacks!
1) Nitrogen reflow soldering to increase the cost of Nitrogen reflow soldering technology requires more than ordinary reflow soldering price is higher, so the cost will increase.
2) Nitrogen reflow soldering on the process ability to require a higher Nitrogen reflow soldering is a more reliable as well as a higher content of the technical requirements of the furnace temperature curve, if there is no effective control of the furnace temperature curve in the process, may result in other welding qualities
In summary, the patch processing ammonia reflow soldering certainly has a better role and benefits, but also should be combined with product characteristics, cost control, process capabilities and other factors to consider whether the need for additional ammonia reflow soldering.

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