With the rapid development of wide-bandgap semiconductors, artificial intelligence chips, and high-power-density electronic systems, power electronic devices are evolving toward higher operating frequencies, greater integration, and higher power densities, imposing increasingly stringent requirements on the low-temperature processability, electrical and thermal transport properties, and long-term service reliability of packaging interconnect materials. Sintered silver interconnect layers possess a high melting point, high thermal conductivity, high electrical conductivity, and excellent high-temperature stability, and are therefore regarded as a promising direction for next-generation power chip interconnect materials. However, existing silver sintering processes are generally performed at 175–250 °C. Such relatively high processing temperatures increase the risk of thermal damage to temperature-sensitive devices and limit compatibility with certain advanced packaging processes. Silver nanoparticles (AgNPs) possess a high specific surface area and a strong driving force for surface diffusion. However, to suppress agglomeration, their surfaces are typically coated with relatively thick and stable organic layers. These organic species are difficult to remove sufficiently at low temperatures, thereby hindering direct particle-to-particle contact and atomic diffusion. Moreover, AgNPs undergo substantial shrinkage during drying and sintering, which can readily result in the formation of pores or cracks. By contrast, silver microparticles (AgMPs) contain fewer surface organics and exhibit less sintering shrinkage. Nevertheless, their relatively low specific surface area and insufficient effective contact sites make it difficult to form a continuous interconnection network at low temperatures. Therefore, synergistically exploiting the structural stability of microparticles and the high sintering activity of nanoparticles while regulating particle packing, surface organics, and interparticle diffusion pathways is a critical challenge that must be addressed to achieve high-performance silver sintering interconnections at lower temperatures of 150 °C or below.
The research group led by Mingyu Li at Harbin Institute of Technology (Shenzhen) developed a bayberry-like AgMP/AgNP micro–nano composite sintered silver paste (AgPs-BM), in which bayberry-like porous silver microparticles serve as the primary structural framework and silver nanoparticles act as the filling and interconnecting phase. The bayberry-like AgMPs feature a low surface organic content, a relatively high specific surface area, and abundant surface pores. The AgNPs not only fill the large voids formed by the packing of AgMPs but are also distributed between adjacent AgMPs and at particle–interface regions, thereby increasing the number of effective contact sites and establishing interparticle connections. In addition, the AgNPs can fill the surface pores of the AgMPs, shifting the sintering behavior of the AgMPs from predominantly individual-particle self-sintering toward the growth of an interparticle interconnected network.
Furthermore, in the composite system, the surface pores and pore edges of the bayberry-like AgMPs provide spaces for the migration and accommodation of residual organic species from the AgNP surfaces during sintering, thereby reducing the likelihood of their persistent accumulation at critical interparticle contact interfaces. This design synergistically enhances micro–nano particle packing, sintering-neck growth, and interfacial bonding, enabling high-strength sintered interconnections at an ultralow temperature of 125 °C.
The resulting bimodal AgPs-BM system achieved a joint shear strength of 37.82 MPa and a sintered-film resistivity of 9.85 μΩ·cm after sintering at 125 °C under 15 MPa for 10 min. Compared with the pure microparticle and pure nanoparticle systems, its shear strength increased by 136.99% and 82.97%, respectively, while its resistivity decreased by 29.54% and 32.75%, respectively. When the sintering time was extended to 20 min, the shear strength further increased to 60.15 MPa. Notably, AgPs-BM still achieved a shear strength of 21.19 MPa under pressureless conditions at 125 °C for 60 min. This work provides a material design strategy for electronic packaging interconnections processed at lower temperatures.
About the Author
Mingyu Li received his Ph.D. in Engineering and is a professor and doctoral supervisor at the School of Integrated Circuits, Harbin Institute of Technology (Shenzhen). He serves as Director of the Key Laboratory of Printed Electronics Technology of the Ministry of Industry and Information Technology and Director of Sauvage Laboratory for Smart Materials. He has been recognized as a national-level high-level talent. He has undertaken and completed four projects funded by the National Natural Science Foundation of China, as well as multiple other national-level projects. His research focuses primarily on electronic packaging materials and technologies, with particular emphasis on micro- and nanoscale metallic particles and their applications in electronic packaging materials, silver nanowire aerogels and their electronic packaging applications, transient liquid-phase reactive composite solders, and their wetting and reaction behaviors. He has published more than 200 SCI-indexed papers in journals including Nature Energy, Acta Materialia, Journal of Materials Chemistry A, npj Flexible Electronics, Applied Energy, and ACS Applied Materials & Interfaces. He holds more than 40 invention patents and has received one First Prize and one Second Prize of the China Machinery Industry Science and Technology Progress Award, one Second Prize of the Aerospace Science and Technology Progress Award, one Second Prize of the Heilongjiang Provincial Natural Science Award, and one Second Prize of the Shenzhen Natural Science Award. Two of his patented technologies have been transferred and successfully commercialized into products. For more information, please pay attention to his research homepage https://homepage.hit.edu.cn/limingyu .
DOI Link:
https://doi.org/10.26599/NR.2026.94908950
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.
Nano Research
Micro-nano cooperative diffusion in bayberry-like porous Ag microparticle pastes enabling 125°C ultralow-temperature sintering
31-Aug-2026