Why use nitrogen for selective wave soldering

The ultimate goal of all welding equipment or tools is to get better solder joints. Selective wave soldering is a high-precision end-to-point soldering method among all soldering methods; in order to increase the quality and reliability of solder joints. All selective welding equipment is added with nitrogen protection part. Nitrogen is an inert gas , which can improve the wetting ability of the welding surface of the component and the printed board, reduce the degree of oxidation, and accelerate the welding reaction speed. Compared with welding in an air environment, welding in a nitrogen environment can theoretically reduce the required welding temperature, reduce process defects, and form good solder joints.

The selective wave soldering equipment uses and does not use nitrogen. In addition to the changes in the soldering process, the change in the amount of tin dross is obvious. When nitrogen is used, there is almost no tin dross in eight hours of production, and when nitrogen is not used , The tin dross is produced at a hundred times the speed. Choosing the role of nitrogen welding for welding can reduce tin slag and save costs, but users must bear the cost of nitrogen and the initial investment in equipment purchase. Usually need to compromise the above two factors, so it is necessary to determine the cost of reducing maintenance and due to better solder joint infiltration and lower defect rate.

So why is nitrogen protection, can other gases be used? Because the chemical properties of nitrogen are relatively stable , it generally does not react with other metals. In addition to nitrogen, other chemically inactive and stable gases are also available. Such as rare gases: He, Ne, Ar, Kr, etc. The main reason for choosing nitrogen is that nitrogen accounts for 78.08% (volume fraction) of the total atmosphere. Nitrogen is chemically inactive, and it is difficult to react with other substances at room temperature, so it is often used to make preservatives.

Selective wave soldering nitrogen-filled soldering usually adopts gas dispersion technology, which means that the solder is sprayed into the solder wave required by the design through an electric pump or an electromagnetic pump . By injecting nitrogen into the solder pool, the nitrogen is evenly diffused on the surface of the wave. , To achieve the purpose of inert gas protection, and at the same time let the printed circuit board pre-installed with the components pass through the solder wave to realize the mechanical and electrical connection between the component soldering end or the pin and the printed board pad.

Why should nitrogen protection be used for selective wave soldering? The main purpose is to improve the quality of solder joints, reducing the oxidation of the solder, and that's it, is more selective soldering Hundred Questions 4 hope the above explanation can be short mustaches doubts selective soldering must use nitrogen intent, if the industry Dade different views Welcome to the communication exchange of opinions and suggestions.