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64 PCB007 MAGAZINE I NOVEMBER 2020 indicators cost $10 for 20 and are used to mea- sure the hydrogen peroxide concentration in mild etches in less than a minute. Another ex- ample is using a simple $18 hydrometer to con- trol etches, cleaners, acid, and plating in less than half a minute. Using these simple mea- surement techniques, the chemical concentra- tions can be used at a lower level and save costs (Figure 1). The program was so successful that I have kept the ideas and built on them over the last 40 years. My crowning achievement in 2009 was the perfection of a small cyclic stripping voltammetry (CVS) unit that I could build for $200, replacing the laboratory $20,000 unit, al- lowing me to have a continuous CVS measur- ing unit on each copper plating tank. At that time in China, I had 68 2,000-liter copper plat- ing cells/tanks in use, so the newly added con- trols greatly improved performance and yields. The most significant chemical processes are controlled by key chemical concentrations. This program introduces to production man- agement and technical personnel low-cost ap- proaches to simple, low-cost methods of moni- toring and controlling chemical processes used in PWB fabrication, chemical coatings, sen- sor manufacturing, and electroplating/electro- forming. Some techniques cost as little as $20 through ion-specific electrodes and simple col- or-wheel comparators, as well as pool chemis- try chlorine analysis or battery-powered spec- trophotometers that run only a few hundred dollars. All these methods can be taught and used by production personnel. A formal lab is not required, but these techniques can be used by labs to increase their productivity and the number of chemistries controlled. This is espe- cially true for the crucial copper electroplating Figure 1: Frequent or continuous chemical monitoring leads to lower costs and higher yields.

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