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74 PCB007 MAGAZINE I JANUARY 2019 Venting Processes Locally with Recycled DI Water As seen in Figure 1, there is minimal venting, as much is recovered at the machine itself, but the minimal venting is handled locally by a scrubber and the deionized (DI) water is recycled with the other rinse waters (Figure 2). Continuous Chemical Analysis and Dosing The continuous analysis and dosing allow the facility to minimize concentrations and maximize process controls for higher quality, fewer costs, and lower dragouts. This is a major contributor to the Lean and green strategy (Figure 3). Chemical Regeneration Chemical regeneration with make-up from rinse water concentrations also contributes to the zero-effluent strategy as well as lowering chemical costs and maximizing process controls. There are seven major systems (Table 2). Some of these systems are shown in Figures 3 and 4 as well. Cupric Chloride Copper Etching The cupric chloride etchant is utilized for the majority of inner layer, panel copper, and final outer layer etching. This cupric is analyzed and regenerated to provide a much more consistent etch rate than normal cupric chloride. It is regenerated with oxygen and hydrochloric acid by an oxygenator unit, eliminating the need for hydrogen peroxide, chlorine gas, or other hazardous chemicals (Figure 5). The copper is removed from the etchant and rinse water by a proven industrial technique c a l l e d l i q u i d - l i q u i d extraction first developed at Hewlett-Packard for PCB alkaline etchants back in 1974. Over the last 35 years, over 200 of this type of recovery system (100 for PCB etchants) have been installed worldwide [2] . It is very common Figure 3: (a) Fresh chemicals represent only 40% of the total chemical systems costs; (b) automatic chemical dosing stations for processes; and (c) continuous monitoring and dosing allow the lowest level of operating chemical concentrations. (Source: Stepinski innovations LLC [3] )