Use of Nitrogen in Reflow soldering in the PCBA process consideration is becomes a common during reflow soldering. In reflow soldering process, components are placed on top of the printed circuit boards on solder pads with solder paste applied, when paste is heated in presence of oxygen will form oxides which are non-solderable surfaces and results poor wetting of molten alloy on printed circuit boards.
The nitrogen is used to minimises oxidation of the surfaces to be soldered. The chemical reactions necessary for soldering require high temperatures but metal oxidizes at a faster rate with heat applied and oxidation weakens the solder. Therefore, nitrogen gas is used in order to create a clean, dry, inert atmosphere that eliminates the presence of oxygen.
Refineries, pharmaceutical companies, the petrochemical industry use tank blanketing to prevent contact with oxygen and as a way to avoid potentially hazardous conditions. The blanketing process controls the atmosphere above a combustible or flammable liquid, and this reduces the ignition potential. Manufacturers use the method for storage of adhesives, chemicals, fuels, pharmaceuticals, photographic chemicals, inks, and soaps.
Selective Soldering is a process used in electronics manufacturing as an alternative or follow-up to reflow soldering where the heat of the reflow oven may be too high for particular surface mounted components on printed circuit boards. Selective Soldering may follow the reflow oven process for soldering other surface mount components able to withstand that level of heat. In these cases, great care must be taken in the selective soldering of additional components to the printed circuit board in order to avoid damaging those reflow soldered components.
Nitrogen gas may be used in the process of Selective Soldering to eliminate the possibility of oxidation that would weaken the solder. The chances of oxidation increase with the added heat that is required for soldering. Nitrogen is a clean, dry, inert gas that, when applied during the soldering process, can work to displace the presence of oxygen and therefore avoid the threat of oxidation.
Using gaseous nitrogen to generate an inert atmosphere during wave soldering to minimize solder oxidation is well known, which not only saves solder material and lessens maintenance requirement but also improves solder wetting and ensures the quality of the formed solder joints. This nitrogen inerting technology can be applied in an existing wave soldering machine by inserting in molten solder pot a protective housing with Nitrogen diffusers mounted inside. Nitrogen gas blanket across the solder pot can be formed, thus reducing the tendency of solder oxidation.
A dry box is a completely enclosed chamber designed for working in a preferred atmosphere, which is inerted using Nitrogen. The dry boxes are constructed of acrylic polymers, they are permeable to moisture.
Continuous purging a dry box involves flushing moisture and oxygen laden air out of the cabinet using a steady flow of nitrogen. A purge of nitrogen gas is generally preferred in a large cabinet because such systems achieve a uniformly low-humidity storage environment more quickly than desiccant-based systems, particularly where ultra-low RH levels are required. Nitrogen can be fed into multiple locations in a large cabinet, often using a rear plenum as a distribution chamber. Nitrogen purged dry box also prevent contact with oxygen, making them ideal for anaerobic applications.
De-ionised water is widely used by electronics manufacturers. Nitrogen gas is used to blanket bulk storage of this essential commodity to preserve the quality of the water, preventing ingress of airborne bacteria and particulate.
