Reliability assessment for the PoP lead free solder joint through temperature cycling test

Trends in the packaging of semiconductors are towards miniaturization and high functionality. The package-on-package (PoP) with increasing demands is beneficial in cost and space saving. This study conducts the assembly of the PoP component through the stacking process. Samples are subject to thermal cycling test condition, 0°C to 100°C. The failure of samples is defined as when the measured resistance is above 3D. The cross-section and dye penetrate analysis are used to investigate the failure modes. Results shows that majority of failure occurred to bottom components. The failure location is at interface between component pad and the solder joint due to the CTE mis-match between bottom chip and the PCB. The warpage of PoP substrate has resulted in variation in standoff height across the components. Failure data is verified to follow a Weibull distribution. The parameters of the Weibull distribution are identified. The expected life for the PoP solder joint is determined to be 5600 cycles in the temperature range of 0°C to 100°C.