Reliability study of 3D packaged memory under coupled damp and thermal conditions

With the widespread adoption of advanced packaging technologies such as 3D packaging, it has become increasingly important to study the impact of coupled hygrothermal stress on the reliability of microelectronic devices employing these novel packaging techniques. This paper employs finite element simulation and experimental validation, focusing on 3D packaged memory modules, to investigate and analyze the reliability of 3D packaged devices under coupled hygrothermal stress. The research results indicate that the heat dissipation vents of 3D packaged memories serve as the primary entry points for moisture. The areas near these vents are significantly affected by coupled hygrothermal stress. The encapsulant material is prone to failure under the action of coupled hygrothermal stress, while the internal structure remains relatively unaffected. Kirkendall voids appear in some of the solder joints within the internal interconnects of the 3D packaged memories. The continuous exposure to high temperature and high humidity conditions associated with coupled hygrothermal stress accelerates atomic diffusion, leading to the generation of more vacancies that migrate towards the already formed voids, thereby promoting the continuous expansion of these voids. • Under humidity-thermal loads, maximum stresses occur in the metal casing's groove area and bottom region of 3D-packaged memory, inducing epoxy resin overflow with micro-pores. Moisture ingress accelerates thermomechanical degradation. • Steady-state humidity/temperature accelerates atomic interdiffusion in solder joints, causing vacancy aggregation on the Sn side to form Kirkendall voids. • Thermal expansion dominates overall device stress, while moisture stress significantly impacts groove areas. Coupled humidity-thermal stress analysis is critical for reliability evaluation of 3D-packaged devices.