Qualification of the Assembly Process of Flip-Chip BGA Packages ...

4.4.2.1 Bump Dimensions Measurements
Texas Tech University, Nivetha Shivan, May 2012
Figure 4.18 shows the Solder Bump located on the metal pad on the die.
Figure 4.18: Bump Dimensions
� Bump pitch – Measurement of the distance between two bumps
� Die passivation opening – Measurement of the opening of the Oxide/Nitride
passivation layer (the layers which protect the final device metal from stress
conditions)
� Final metal pad – Measurement of length of the Aluminium metal pad
� Under Bump Metallization size – Measurement of size of UBM (the compatible
layer between the bump metallization and the final device metallization)
� Bump Height
� Bump Diameter
4.4.2.2 Underfill Fillet Height Measurement
The underfill fillet height is the height of the underfill around the die in the vertical
direction. This measurement should be done from all four sides of the package. Filler
height is an important measurement criterion. It is not supposed to be more than 100% of
the die thickness and creeping of the underfill material over the die should not happen
due to consequences like die edge cracks. Figure 4.19 shows the underfill location in a
flip chip package. Figure 4.20 shows the SEM image of the dimensions of the underfill.
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