Micron- and nano-sized copper sintering pastes: Materials, processes, and applications

Cu sintering pastes have attracted growing attention as promising interconnect materials for advanced electronics. This review summarizes recent advances in the sintering mechanisms, material innovations, process optimization, and applications of micron- and nano-sized Cu sintering pastes. Early-stage sintering is driven by size- and curvature-dependent melting, while later stages follow plastic flow and grain-boundary diffusion, enabling multiscale modelling of the sintering process. For micron-sized Cu sintering pastes, innovations such as surface functionalization, additive incorporation, and particle engineering have been developed to enhance sintering activity and packing density. Process optimization in terms of temperature, pressure, duration and atmosphere is crucial for improving performance and reliability, enabling applications in via filling and high-temperature joint fabrication. For nano-sized Cu sintering pastes, combining wet-chemical synthesis with surface ligand engineering has successfully improved oxidation resistance. Balancing particle size and ligand coverage is critical for minimizing residuals and promoting effective densification. Future research efforts will focus on the development of rapid, low-temperature, pressureless, air-sintering technologies and the establishment of reliability assessment methodologies under harsh environmental conditions. Driven by the demands of flexible electronics, 6G communications, and power packaging, Cu sintering pastes are expected to expand their industrial relevance across consumer electronics, aerospace, and emerging energy sectors.