Grain orientations are a significant factor under high-density current stressing, but there are few literature reports about the influence of grain orientation on electromigration in composite solder joints. Most research relating to the electromigration behavior of composite solders have been carried out by adding different kinds of reinforced particles in order to relieve the electromigration phenomena, while the impacts of grain orientation on the electromigration have been neglected. In this paper, Sn-3.5Ag composite solder joints reinforced by 2 vol.% Cu were fabricated to investigate the effects of Sn grain orientation on electromigration. The one-dimensional single-grained solder joints were stressed under a constant current density of 10 4 A/cm 2 for different times at room temperature. The samples, of which the c -axis of the Sn grains was nearly parallel to the electron flow direction, exhibited serious electromigration-induced phenomena after current stressing for 528 h. However, electromigration was not observed in the samples where the Sn grains had their c -axis perpendicular to the electron flow direction. Therefore, the grain orientations have a great influence on the electromigration behavior in composite solders and Cu atoms moved faster along the c -axis of the Sn grains than along the a - and b -axes during current stressing.
Mingyue Wang,Xiaohua Jia,Zhiqiang Shan,Haojie Song
Graphene-epoxy coatings show promise for protecting marine infrastructure from extreme environments, but their long-term durability and dual wear-corrosion resistance are limited by poor graphene dispersion and random orientation in the matrix. To address this challenge, we developed a highly ordered graphene-enhanced epoxy‑copper composite (DGr-ILs-EP@Cu) via electrophoretic deposition (EPD). Ionic liquids (ILs) enabled one-step exfoliation and functionalization of graphene nanosheets, yielding a stable, positively charged dispersion for EPD. Under an electric field, the graphene nanosheets (DGr) aligned directionally, achieving an ultralow friction coefficient (0.025–0.06) with exceptional stability over 10 h of wear testing. Crucially, copper ions released in situ from the EPD electrode enhanced the coating's wear resistance, approaching near-zero wear rates. The aligned graphene structure also extended the diffusion path of corrosive species, increasing the coating's impedance modulus by 2 orders of magnitude compared to disordered composites. By correlating microstructure (orientation degree) in the EP matrix with performance metrics (friction coefficient, electrical conductivity, and impedance modulus), we demonstrate a multifunctional coating design and new insights specifically optimized for complex environments.
危险品化学品经营许可证（带存储）