With the development of packaging devices towards high performance and high density, electronic devices are subjected to thermos-electric stresses under service conditions, which has become a particularly important reliability problem in microelectronics packaging. The reliability of the chip under thermo-electric stresses is studied in this paper. Firstly, thermo-electric coupling experiments were carried out on two solder joint structures of Ni/Sn3.5Ag/Cu and Ni/Sn3.5Ag/Ni. The interface evolution of solder joints under different current densities was analyzed. The reliability of the two structures under thermo-electric stresses was compared and analyzed. After that, three-dimensional finite element analysis was employed to simulate the current density, Joule heat, and temperature distribution of the flip chip. Finally, through the combination of experiment and simulation, the distribution of Joule heat and temperature of the chip was analyzed. The results show that the Ni/Sn3.5Ag/Ni structure has better reliability than the Ni/Sn3.5Ag/Cu structure under thermal-electric coupling. In addition, when the Ni layer was used as the cathode side, and the current density was higher than 5×104A/cm2, the dissolution failure of the Ni layer occurred in two structures. Because the higher current density generated a large amount of Joule heat where the current was crowded, resulting in excessively high temperature and rapid dissolution of the Ni barrier layer.

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Under the action of electro-thermal-mechanical coupling, the failure and performance degradation of electronic devices are prone to occur, which has become a particularly important reliability problem in microelectronic packaging. The improvement of flip chip reliability by using thermal interface materials was studied. First, a three-dimensional finite element model of the flip-chip packaging system, and finite element simulation of electric-thermal-force multi-field coupling were conducted, and the Joule heating, temperature distribution, thermal stress and deformation of the flip-chip under high current density was analyzed. At the same time, the influence of thermal interface material thermal conductivity and operating current on flip chip reliability was studied. Then, the reliability experiment of the flip chip connected to the radiator under high current density was performed, and the temperature change in the flip chip under different thermal interface materials was obtained. Finally, through the combination of experiment and simulation, the influence of thermal interface materials on flip chip reliability was analyzed. It is further confirmed that the reliability and service life of electronic devices were effectively improved by using the high thermal conductivity BNNS/epoxy composite material prepared in this paper.