The die in this CSP is positioned face down, and is interconnected by solder balls. The back or upper side of the die is overmolded. The die has approximately the same area as the package. To image the die face through the molding compound, a C-SAM frequency of 50 MHz was used.
The red area is a massive delamination of the molding compound from the back side of the die. Normal thermal expansion and contraction during use could cause this delamination to grow. Because the die is as large as the package, a complete delamination would allow the die to be exposed to environmental contamination. |
