The Second stage
As regenerated etchant is added to the etching module, regenerated rinse water is added to the flood rinse module. Regenerated rinse water contains approximately 7 G/L ammonium chloride, 5 ppm copper, and free ammonia. It is a very efficient rinse agent that doesn’t attack resist and can be recycled. As the rinse water cascades through the flood rinse module it becomes spent and is sent to a buffer tank for storage before processing by the Mecer system. Spent rinse water is fed into the second extraction stage of the Mecer system where the copper is reduced from ~2 G/L to 5 ppm. The regenerated rinse water is sent back to a buffer tank for storage and reuse by the etching machine. A small portion of this material is also bled off to waste treatment to compensate for the volume of water being added to the process through the fresh rinse module. Typically DI water is added to this module at a rate of 50 L/H, therefore reducing rinse water consumption for a typical etcher by 90%.