If you’re looking to avoid evaporation as a drying technique in a cleanroom, you may be interested in the Marangoni System.
When water evaporates, because it is leaving as a gas, it leaves behind water spots. In a controlled environment, this is something to avoid; the water spots are basically made of contaminants. In order to remove water, then, some people consider the fascinating Marangoni System.
James Thomson found that gradients in surface tension arise from concentration differences in solution. After that, Carlo Giuseppe Matteo Marangoni found that liquid will flow along a gas-liquid or a liquid-liquid interface from areas of low surface tension to high. These two combined discoveries led to the Marangoni System.
The Marangoni effect is stimulated by anything that reduces surface tension. A cleanroom dryer would use a DI water bath with a headspace of IPA in nitrogen. IPA dissolves in water, resulting in lowered surface tension, allowing water to flow away from the surface of the object being cleaned, thereby leaving it dry. The object experiences the effect as it is slowly withdrawn vertically from the bath.
The huge benefit to this method is that all the unwanted water – containing soluble materials like minerals – is removed as a liquid. Therefore, they are not left behind as water spots.
Unfortunately, only flat surfaces can be dried with this approach. Fluid force produced by differential surface tension is diminished when in competition with other forces like convection or gravity.
Also, the slow rate of withdrawal yields only about 1 to 10 single pieces dried every two minutes. This really limits the application when you need multiple pieces dried. What may benefit most from this method, then, are large flat surfaces, like flat panel displays.
As with any cleanroom decision, the efficacy of the Marangoni System will depend on the application. If you need cleanroom validation or certification, contact the experts at Gerbig Engineering Company. 888-628-0056; firstname.lastname@example.org.