The semi-conductor industry requires high-purity E-1 grade water during the plating process, particularly in the final stages of cleaning to remove residual contaminants and soldering flux. Ampac USA manufactures reverse osmosis/ de-ionization systems (RO/DI) that produce water at high resistivity and high purity for circuit cleaning.
Resistivity of 1 megaohm-cm is the minimum for semi-conductor processes. Ampac USA RO/DI systems produce water with at least 18 megaohm-cm resistivity. This is achieved through a de-ionization stage during pre-treatment. To minimize the system's operational effort, an ideal source water would already be pre-treated, such as municipal supply. The supply would then be filtered for sediment and pre-treated to remove microorganisms and dissolved ions.
The water is then passed through a de-ionizing multimedia mixed bed housed in cartridge before being sent through the reverse osmosis membrane to remove any residual dissolved ions.
E-1 water is considered "corrosive" due to its appetite for absorbing ions and impurities, thus reducing its "purity" if exposed to these contaminants. To avoid this, the entire treatment process as well as delivery of the produced E-1 water must be closed to outside contamination.