The electronics assembly industry is constantly looking for ways to reduce process costs and, at the same time, satisfy the demand for higher yields and fewer defects that comes from end customers.

In this regard, several companies that assemble electronic boards for their own account or for third parties have been using industrial gases, mainly nitrogen, to achieve these goals for some time now.

The main application of gases in this sense is the use of inert atmospheres in brazing processes, obtained by replacing atmospheric oxygen with an inert gas such as nitrogen.

By operating in this way, it is possible to obtain, around the brazing area, very low concentrations of residual oxygen, with consequent notable advantages especially in terms of product quality and reduction of operating costs.

Nitrogen in the SMD process

The most common defect in SMD (Surface Mounted Device) assembly technology is the misalignment of components on the pads due to insufficient surface tension.

The latter, in turn, can be caused by the oxygen present in the atmospheric air: oxygen causes the formation of oxides on the surface of the joints and the solder alloy, which prevent an effective connection and create intermetallic compounds that make the joints less tenacious. Furthermore, oxygen promotes the phenomenon of “dewetting”.

In SMD technology, the use of high-purity nitrogen instead of atmospheric oxygen allows avoiding the negative effects described above, obtaining significant advantages, including above all:

• robust and consistent joints, with consequent less reworking.
• a reduction in residues of up to 66%, depending on the different pastes used.

Nitrogen in the THT process

In the case of THT (Trough Hole Technology), the most common defect consists in the failure or partial rise of the alloy in the holes.

In this case too, the use of nitrogen instead of atmospheric oxygen leads to significant advantages, including:

• a reduction in metal oxides.
• fewer defects (especially on small thicknesses).
• a reduction in spray flux of up to 60%.
• less maintenance of the welding machine components.
• brighter joints.
• a reduction in slag of up to 80% and therefore fewer adjustments of the recirculation pump.

Other uses of gases in the electronics industry

Conditioning of components

Many of the components used in the electronics industry can be placed in special cabinets where nitrogen is flowed.

In this case, the function of the gas is to eliminate humidity, remove oxygen particles from the surface and increase solderability.

Low-temperature environment tests

To test assembled electronic boards that must withstand low temperatures or that are subjected to large temperature fluctuations, chambers in which liquid nitrogen or liquid carbon dioxide is injected are often used. The so-called “cryo-testing” is also used to verify the long-term reliability of the assembled component, testing the different thermal expansion coefficients of the various components.