Moisture damage usually appears as physical damage to the component. The first indication would be externally observable changes to the package in the form of bulging or fractures to the outer surface of the component. Internally observable indicators of moisture damage typically include fractures to the die inside the package and lifted or fractured wire bonds. These conditions would be apparent during transmis-sive x-ray inspection. Another symptom of moisture would be inconsistent solder joint sizes that result from package deformation during the liquidus phase of the reflow process. No issues were observed with the large BGA components here (FIGURE 1). X-ray showed that the die, wire bonds and solder balls appeared well-formed and provided no indication as to a loss of functionality.
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