Issue link: https://iconnect007.uberflip.com/i/1288481
82 PCB007 MAGAZINE I SEPTEMBER 2020 tions were prepared, and the pictures are sum- marized in Figure 3. What becomes obvious when comparing the failure images in Figure 3 is that it seems to be in particular if the corrosion is spread over wide areas of the nickel/gold interphase, not necessarily penetrating deep to the nickel. Rather than that, the corrosion is concentrated to the upper surface, having an overall depth of often not more than 100 nm. Such defects Wetted areas on defect pads with IMC. Defect structure on unsoldered pads. Dewetted areas on defect pads without IMC. Wetted areas on defect pads with IMC. Defect structure on unsoldered pads. Dewetted areas on defect pads without IMC. Figure 3: Exemplary SEM images of defect pads in a cross-section. Au Layer Corroded Ni-surface Ni-layer Solder IMC Ni-layer Solder Ni-layer Solder Ni-layer Solder IMC Ni-layer Au Layer Corroded Ni-surface Ni-layer