The effect of initial warpage of top component on POP assembly

Higher packaging density is driven by the multifunctional requirements and size shrinkage in handheld applications, which was greatly improved by the 3D packaging technologies. Package-on-package (POP) is one of the 3D packaging solutions, in which components can be fully tested good prior to integration. However, the package warpage due to mismatch of materials properties is a greater challenge for POP than other packaging types during stack process of POP components. Initial components warpage may affect the assembly processes due to the non-coplanarity. The value and direction of warpage could result in the solder joint openings and affect the stresses distribution in the device working state. In the study, effects of initial warpage of top component in POP with two components stacked on the assembly and POP working state were investigated by Finite elements analysis (FEA). The different powers of logic die were considered in the analysis, which were applied on the dies as thermal loading under the device working state. The analysis results in this study provide some clues and guideline for the component initial warpage control in POP, which influence the POP assembly yield and reliability in the device working state.