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JULY 2019 I SMT007 MAGAZINE 107 of scratches on rejected PCBs by the manufac- turer, could not be controlled. Most artificially created scratches were inten- tionally made deeper and wider than those on PCBs rejected by the manufacturer, as was shown in Figures 8 and 9. The integrity and reliability of wire bonds made on artificially- created scratches were considered a worst-case condition compared to those made on relatively shallow scratches on PCBs rejected by the man- ufacturer. Figures 14 and 15 show examples of scanning electron microscope (SEM) images of scratches with elemental analysis using energy dispersive spectroscopy (EDS). Figure 14 shows an example of scratches on a PCB rejected by the manufacturer during the PCB manufacturing process, and Figure 15 shows an example of scratches created inten- tionally for this study. The amount of gold detected on the surface of the scratched area is significantly reduced compared to that on the surface without scratches, particularly for Fig- ure 15. Meanwhile, the amount of palladium and nickel detected on the scratched area was significantly increased since palladium and nickel were exposed to the surface. Nickel was detected significantly in some isolated areas indicated as Area 3 in Figures 14 and 15. Figure 14: SEM image (L) and EDS analysis (R) result of a scratch on a rejected PCB from the manufacturer. Figure 15: SEM image (L) and EDS analysis (R) result of a scratch intentionally created for this study.