Sintered copper (Cu) nanoparticles have emerged as a promising substitute for sintered silver (Ag) nanoparticles in power electronics packaging, offering comparable electrical and thermal conductivities, superior mechanical strength, and lower cost. However, the complex interactions between microstructure evolution, interfacial bonding, and mechanical performance during sintering remain insufficiently understood. This research investigates the mechanical behavior, fracture mechanisms, and reliability of sintered Cu nanoparticles through a combination of microscale experiments and multiscale modeling. The studies revealed the anisotropic fracture toughness of sintered Cu nanoparticles, developed an Anand viscoplastic model to describe high-temperature deformation, and quantified interfacial strength while elucidating the effects of oxidation on bonding quality. Furthermore, the influence of particle morphology on mechanical properties was examined using micro-cantilever bending tests and phase-field fracture simulations. Overall, this work advances the understanding of sintered Cu nanoparticles and supports the development of reliable and cost-effective interconnect materials for next-generation power electronics.
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