Flip Chip disbonded solder bumps and halo defects - Application Note 354
Sample & Method
A Flip Chip package was imaged from the top side (through the back of the die) at the high acoustic frequency of 230 MHz using high-resolution 1024 x 960 pixel scanning. Gating was on the interface between the die face (i.e., circuit side) and the underfill material.
Since gating was on the interface between the die face and the underfill, it also includes the bonding of the solder bumps to the bond pads on the die face. Red bumps are those where bonding is absent or incomplete. In addition, next to some bumps (both bonded and disbonded) are small red halo defects. These are vertical delaminations between the underfill and bump caused by a failure of the fluid underfill to thoroughly wet the bump.