纳米银浆料烧结机理及导热性能分子动力学仿真

Molecular dynamics simulation study of sintering mechanism and thermal conductivity of nano-Ag particles

针对纳米颗粒的烧结机理不明确及烧结过后热导率显著下降等问题进行探究.利用分子动力学仿真的方法,通过热导率的计算验证了势函数选取的正确性,模拟了银纳米颗粒的烧结过程,观察了烧结过程中微观结构的变化,得到了烧结颈生长长度与烧结时间拟合关系,并计算了烧结颈处声子热导率变化情况,最后通过透射电子显微镜观察到试验烧结纳米银颗粒具备与仿真结果相同的五重孪晶结构.结果表明,五重孪晶为纳米颗粒烧结后的稳定结构,纳米颗粒烧结过程中烧结颈生长长度与时间成幂函数关系,烧结颈处微观结构使纳米银的热导率降低了4.42%.

Nanosilver paste can achieve low-temperature sintering and high-temperature service,due to its special size effect and high specific surface area,which has a broad application prospect in the third-generation semiconductor packaging.However,the sintering mechanism of nanoparticles has not been clear and the thermal conductivity has decreased significantly after sintering,which needs to be further investigated.In this paper,the sintering process of silver nanoparticles was simulated by molecular dynamics simulation.The correctness of the potential function was verified by the calculation of thermal conductivity,firstly.And then the microstructural changes of silver nanoparticles were observed,the relationship between the sintering neck growth length and the sintering time was obtained,and the change of the phonon thermal conductivity at the sintering neck was also calculated.Finally,the experimental silver nanoparticles with the same characteristics as the simulation results were observed by the transmission electron microscope.The results showed that the fivefold twins were the stable structure of nanoparticles after sintering,the sintering neck length growth during nanoparticle sintering was a power function of time,and the microstructure at the sintering neck reduced the thermal conductivity of nanosilver by 4.42%.