Fatigue behavior of 3D stacked packaging structures under extreme thermal cycling condition

Abstract

In deep space exploration environment, electronic devices face severe tests. C4 solder joints and TSV, as the weak links of the three-dimensional packaging structure, have a significant impact on the reliability of the packaging structure. This work focuses on the typical three-dimensional packaging structure and utilizes finite element software to analyze the influence of extreme thermal cycling on the fatigue life of packaging structure. The results show that under the extreme temperature range of -100∼120 °C, the maximum stress concentration of a typical 3D packaging structure occurs at the interface between the TSV and Si chip, and the TSV and C4 solder joints remote from the center bear greater stress and strain. The maximum stress of TSV appears at the end edge of TSV at the upper left corner. The maximum stress of the C4 welding spot appears on the second welding spot in the rightmost column. The most dangerous TSV fatigue life is 1.07 × 107 cycles calculated by combining the finite element simulation results with the Coffin Manson model. The life of the most dangerous C4 solder joint is 2892 cycles. C4 solder joint is the failure-sensitive location of the three-dimensional packaging structure under extreme ambient temperature, and optimization design is required in the subsequent work to improve its reliable life.

Keywords

• Finite element simulation
• 3D packaging
• Equivalent plastic strain
• Extreme temperature
• Thermal fatigue