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APRIL 2018 I PCB007 MAGAZINE 85 The first-generation DAS, the Hewlett-Pack- ard 8450A, had five sample cells, a beam direc- tor and software to automate data collection and analysis. The second-generation 8452A was 38% less expensive and used a color dis- play. The third generation, the Agilent 8453E, is only 68% of the original DAS cost but has 25% larger wavelength sensitivity. These three units are seen in Figure 10. The Agilent DAS is an ideal piece of instrumentation to have in your PCB chemical laboratory. It allows easy experimentation of wavelengths, concentra- tion calibration and automation of chemical analysis. Some of the automatic analyses per- formed at HP's Sunnyvale PCB shop were: • Saccharin additives • Ni component 67 additive • Nickel concentration • Impurities • Boric acid • Chloride Figure 10: Photos of the first three generations of diode-array spectrophotometers from Hewlett-Packard (now Agilent). One Agilent DAS allowed the replacement of manual titrations and an expensive atomic ab- sorption spectrophotometer (AA) for analysis of tin, nickel, gold, copper, palladium, micro- etches, and catalysts. Table 4 shows some of the analysis of PCB chemistries using the Agi- lent DAS, as compared to manual titration or atomic absorption. DAS spectra scans of three components of a nickel plating bath and palladium in cata- lyst and the differences for different concen- trations of nickel and palladium can be seen in the new I-Connect007 e-book, "Automation and Advanced Procedures in PCB Fabrication" available for free download in April 2018. Ampere-Hour Ampere-hour sensors accumulate the total DC current used for time employed. This de- vice can automatically replenish a chemical based on the current-time setpoint. The inte- gral pump runs for a set number of seconds (2.3 ml per sec.) if energized. It can be cali-