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88 PCB007 MAGAZINE I APRIL 2018 scans are applied that alternately plate and strip a layer of the major metal. The electrical charge required to strip the plate is a measure of deposition efficiency which, under some conditions, can be correlated to additive concentration. Employing scanning or pulse potentials in voltammetry can determine copper and formaldehyde in electroless copper, the gold (I), gold (III) in gold baths, nickel and cobalt levels in hard gold deposits, tin, lead, sulfonic acid and proprietary additives in copper plating baths. The fourth most common analytical tech- nique for PCB processes is the CVS analysis of copper plating additives. Here is an automat- ed laboratory unit for analysis of multiple plat- ing baths. This technique, developed in the early 197 0s by Tench and Ogden at General Dynamics, was crucial in developing high- speed and via filling copper plating. The dr awback on commercially available CVS in - struments is their cost, typically $20,000 to $30,000. The CVS unit in Figure 11 was built Figure 11: A DIY CVS analyzer based on the design of several Asian universities' publications on low-cost instruments to detect diabetes. for less than $250 using plans published by Taiwan universities as a part of a govern- ment program to have a low-cost analytical unit to detect diabetes in the gener al popu- lation. They were looking for the same mol- ecules that are used as additives for copper plating baths . Which Chemical Parameters Can Be Analyzed? Tables 5 through 9 describe chemical param- eters that have been analyzed by sensors or in- struments and can be integrated into automat- ed units. Table 5 shows the eight parameters for electroless copper and MSAP copper plus four parameters for the electroless line. There are 32 chemical parameters that can be analyzed by sensors for different types of electroplating in electronics, connectors and relays (Table 6). There are seven parameters for copper etch- ing (Table 7) and five parameters for the pho- toresist developer (Table 8). Three parameters for smear removal can be analyzed, plus three parameters for acid/clean-