Moisture induced effects in PoP

This paper presents a combined numerical and experimental methodology for predicting moisture-induced effects in Package-on-Package (PoP) assemblies. The hygroscopic warpage of the assembly "PoP" is measured. Its behavior is compared with the individual components "top" and "bottom". The assembly "PoP" absorbs more moisture than the sum of the two individual components, while deforms less than either of the two individual components, which holds much more constrain inside the assembly. In addition, the hygroscopic warpage (20 mum) adds to the thermal warpage (30 mum) for the assembly "PoP", which might lead to more serious reliability problem. Furthermore, a new experimental methodology for prediction of the moisture-induced warpage is validated, and simulation models match the experimental results.