科研之友
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摘要
The exploration and development of the silver sintering technology have attracted much attention in recent years, especially its advantages in applications as achieving interconnects for high-temperature electronics and wide bandgap devices. Electric current-assisted sintering has been proven to be an effective approach to improve the efficiency of the sintering process of silver particles; however, the mechanics of atomic diffusion due to multiple physical fields is yet to be unraveled. In this work, a phase field model is developed to simulate the electric current-assisted silver sintering process by incorporating the electrical-thermal-mechanical effects. Results show that, in addition to the significant sintering neck formation caused by Joule heating when the electrical current passes through the silver particles, the contact force between the particles can be further promoted in the sintering process. The current density is concentrated at the sintered neck between the particles, and the high contact force at the center of the sintered neck can cause a high strain energy density. The neck length gradually increased with the sintering time, due to the combined effect of Joule heating and contact force during the electric current-assisted sintering process. The analysis of the atomic concentration along the neck direction indicates that the electromigration-induced flux could have minor effects on the atomic diffusion. The contact force induces the lower atomic concentration near the contact center of the neck due to the existence of high strain energy density in the early stage of sintering, consequently causing a higher advective force and higher neck formation rate.
