Inert Gas Blanketing in Solder Reflow Ovens

As the use of electronic communication devices such as smartphones, tablets and laptop computers increases, they have progressively become an everyday essential part of modern life, much the same as domestic utilities. With this, also comes the demand and expectation of both customer and industry alike, for reliability and high-quality.

At the heart of these devices lies the PCB (printed circuit board). PCB manufacturers worldwide are continually improving their process and tightening their quality control to minimise any product failures. For the production of PCB’s, the reflow soldering process is the popular choice of manufacturers, allowing for the mass production of circuit boards with intricate surface mount component soldering to the highest quality.

Heat generated within the oven melts the solder and with the aid of solder paste, solders the components to the PCB. Quality is further improved by introducing the use of nitrogen within the oven to create an inert atmosphere. Nitrogen gas blanketing reduces the risk of oxidisation and improves the wetting angles of the soldered joints, therefore increasing the reliability of the product.

The inert atmosphere within the oven is maintained by the use of a gas analyser capable of measuring ppm (parts per million) of oxygen. The oxygen gas analyser detects any residual oxygen, then sends a signal to the PFC (proportional flow control) valve to supply additional nitrogen as required. The Rapidox 1100 PFC oxygen gas analyser, from Cambridge Sensotec (UK), also incorporates closed-loop control that, when bespoke software is integrated with the ovens management system, allows for full control of nitrogen within the oven, resulting in quality assurance, significant cost savings in gas, and an extended life of the PFC valve.