Enhanced Polymer Passivation Layer for Wafer Level Chip Scale ...

3. Slice Modeling
This approach utilizes only a diagonal slice of the assembly in order to reduce computation
time and model complexity. It is usually applicable to packages having octant symmetry
structures. The slice passes through the thickness of the assembly, and captures a full set of
solder joints as well as all major components. The model imposes symmetry boundary conditions
on one surface of the slice. On the other cut surface, a state of general plane strain is imposed.
Therefore, the slice model actually simulates a package that is infinitely long in the direction
perpendicular to the plane of the slice. However, this may cause an underestimation of the
warpage of the package during the temperature cycling, and thus results in under prediction of
the thermal cycle life [90]. Figure 5.3 shows a slice model that includes the package, solder balls
and PCB materials.
Figure 5.3 Slice model [88]
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