Figure 8: Through-hole vias filled with lead and lead-free solders. At this density, it’s hardly noticeable any difference between the two solder technologies.
Figure 9: BGA assembled using lead-free balls and paste with opens and head-in-pillow (HIP) defects. These assembly issues can be caused by erroneous temperature reflow profiles.
Figure 10: Lead-free solder BGA with several of its balls showing excessive voiding. The tear-shape of some of the balls suggests that some of the solder is flowing towards the through-hole vias, an indication of potential issues with the board’s soldermask.
Figure 11: Oblique view of several balls in a BGA assembly using lead solder.
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