Cu nanoparticle sintering bonding is a low-cost die-attach method compared with Ag nanoparticles for power electronic packaging. The joint strength highly depends on the surface metallization of the devices. In present study, the interfacial sintering behavior of copper nanoparticle film (CNF) on different metallizations (Au, Ag, and Cu) was studied. The CNF exhibited a superior shear strength (115 MPa) on Cu substrates when sintered at 250 °C-15 MPa, much higher than that on Ag and Au metallized substrates. The interface connection ratio of bondline-substrate showed the same trend as the shear strength. The neck formation at the bonding interfaces showed no orientation preference. The lateral diffusion of Cu atoms on substrates dominated the sintering bonding, rather than the longitudinal diffusion. The Cu metallization showed much faster lateral diffusion than the Ag and Au metallization, which was confirmed by the neck growth of monolayer nanoparticle sintering and the molecular dynamics (MD) simulation.

中文翻译：

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不同金属化表面烧结铜纳米粒子的界面键合机制

与用于电力电子封装的银纳米颗粒相比，铜纳米颗粒烧结键合是一种低成本的芯片连接方法。连接强度很大程度上取决于器件的表面金属化。在本研究中，研究了铜纳米颗粒薄膜（CNF）在不同金属化层（Au、Ag 和 Cu）上的界面烧结行为。当在250°C-15 MPa下烧结时，CNF在铜基体上表现出优异的剪切强度（115 MPa），远高于在银和金金属化基体上的剪切强度。胶层-基材界面连接率与剪切强度表现出相同的趋势。粘合界面处的颈部形成没有表现出方向偏好。基板上铜原子的横向扩散主导了烧结键合，而不是纵向扩散。Cu金属化显示出比Ag和Au金属化快得多的横向扩散，这一点通过单层纳米粒子烧结的颈部生长和分子动力学（MD）模拟得到证实。