Fig. 4: Impact of the opening angle from the lens on failure analysis.
The 3D EFIT simulation shows the interaction of the SAWs with the metallized TSV wall for different time steps. The position of the lens is kept the same for both opening angles. Excited SAWs using a lens with an opening angle of (a) 60° and b 80°. The point of contact for the SAWs utilizing the lens with 100 MHz, 60° is more in the vicinity of the bottom, whereas for 100 MHz and 80° more towards the open end of the TSV (time steps 1–6). Intensity for the velocity ranges from blue (high) to red (low). c Schematic illustration showing the influence of the opening angle of the lens on the SAW interaction with the TSV. d SAM C-scan image (above) and intensity representation (from dark purple to yellow) in the x-y-plane of a single TSV obtained using 100 MHz, 60° (purple) and 100 MHz, 80° (green). The observed inhomogeneity within the pattern at Z7 is highlighted (white dashed line) to guide the eye for the two different opening angles. e EFIT simulation of the normalized intensity of the absolute values of velocity vectors at the outermost layer of the TSV versus the length of the TSV for 60° (purple) and 80° (green). f SEM image measured on the same TSV. A crack running along the sidewall of the TSV as well as a micron-sized delamination is visible. The latter seems to define to the characteristic Class 2 pattern. See also below the magnified image highlighted with a dashed red frame.
