Thermo-mechanical reliability study on Package on Package (PoP) with Embedded Wafer Level Package (eWLP)

In order to improve the reliability of the proposed test vehicle of the Package on Package (PoP) with Embedded Wafer Level Package (eWLP) using through mold via (TMV) as vertical interconnect. In this paper, the solder joint reliability of eWLP PoP package was studied by the thermo-mechanical finite element simulation under the -40 °C to 125 °C thermal cycle loading conditions. The simulation results show that the critical solder ball is located at the diagonal corner solder ball of the bottom package. The effects of the structural parameters were indentified. The results show that the solder joint reliability can be enhanced by increasing the diameter and standoff of the solder ball, and reducing the overmold thickness of bottom package. Only using appropriate underfill and corner adhesive can enhance the reliability of solder ball. The underfill and corner adhesive material which are benefit to the solder ball reliability under thermal cycle loading were indentified and selected by the simulation.