What are the advantages of nitrogen reflow welding

With the increase of assembly density and the emergence of fine pitch assembly technology, nitrogen filled reflow soldering technology and equipment have emerged, improving the quality and yield of reflow soldering, and have become the development direction of reflow soldering. Nitrogen reflow soldering has the following advantages:

1) Prevent and reduce oxidation

2) Improve welding wetting force and accelerate wetting speed

3) Reduce the generation of solder balls, avoid bridging, and achieve better welding quality

For the introduction of nitrogen in reflow soldering, a cost-benefit analysis must be conducted. Its benefits include product yield, quality improvement, reduction of rework or maintenance costs, etc. A complete analysis often reveals that the introduction of nitrogen does not increase the final cost. On the contrary, we can benefit from it.

It is particularly important to obtain better welding quality by using solder paste with lower activity flux, which can also improve the performance of the solder joint and reduce the discoloration of the substrate. However, its disadvantage is that the cost increases significantly, and this increased cost increases with the amount of nitrogen used. When you need to achieve 1000ppm oxygen content and 50ppm oxygen content in the furnace, the demand for nitrogen varies greatly. Nowadays, solder paste manufacturers are committed to developing wash free solder paste that can perform well in environments with high oxygen content, which can reduce nitrogen consumption. By utilizing the principle that the hot nitrogen layer is lighter than air and less prone to mixing, the heating chamber is designed to be higher than the inlet and outlet, forming a natural nitrogen gas layer in the heating chamber, reducing the compensation amount of nitrogen and maintaining it at the required level.