Sigma has multiple patents for oxidation of etchant with Oxygen gas, completely replacing the conventional and most frequently used Hydrogen Peroxide.

Etchant regeneration

Sigma has also patented the etchant regeneration system that enables closed loop recycling of chemicals, rinse water and plating of pure Copper sheets as a by-product.


Solvent extraction

To transfer Copper from etchant to our plating process, we utilize several solvent extraction steps. Solvent extraction is a method used to mix two immiscible liquids and transfer different compounds based on relative sollubility, in our case Copper. The different densities of the two liquids is then used to separate them from each other again, either using a settler tank or with a centrifuge.


To recycle Copper, we use an electrowinning process that enables plating on sheets. The plating is achieved by adding a current from an inert anode through an acidic electrolyte, in our case Copper pregnant Sulfuric acid, to deposit the metal onto a cathode.


Oxygen source

To feed the Reactor, as Oxygen gas source we either utilize an Oxygen generator or Oxygen gas cylinders depending on the size of the system. 


To enable oxidation, the etchant and the Oxygen gas is transported through a Reactor that uniformly mixes and circulates the compounds to enable the desired reaction.