Highly active bayberry-like porous silver microparticles for fabricating sintered silver with dispersed nanopores and adjustable Young’s modulus

Silver paste is widely used in power electronics as a die-attach material owing to its low-temperature sinterability, high melting point, and excellent electrical and thermal conductivities in sintered joints. However, owing to the mismatch in the coefficient of thermal expansion (CTE) between the joints and chip, the high Young’s modulus of sintered silver hinders the mitigation of the high thermal stress generated during the operation of power modules, which increases the susceptibility of sintered joints to cracking, thereby leading to potential failure. This study developed a facile approach to synthesizing bayberry-like Ag microparticles (AgMPs) through the in situ assembly of silver nanorods, resulting in a uniform distribution of nanoscale structures and mesopores on the particle surface. These particles exhibited a high specific surface area of 2.5389 m 2 ·g −1 , which enhanced their sintering activity, enabling sintering to occur at 149.7 °C. Furthermore, the porous structure of the AgMPs effectively reduced the density of joints formed by sintering AgMP paste, thereby lowering the Young’s modulus of the joints. The small grain size and intricate internal substructure of the joints yielded high shear strength, which reached 112.50 MPa at 250 °C. The Young’s modulus could be adjusted, and the pores provided by the AgMPs maintained the Young’s modulus within a low range (15.11–29.61 GPa), effectively mitigating thermal stress. These new bayberry-like porous AgMPs offer a promising option for die-attach materials in electronic packaging. Graphical abstract