biostudies-literatureUnknown15(1)Lee YFCu-Cu direct bonding using electroplated ultrafine-grain Cu (107.24 nm) was studied in air at 110-150 °C. Unstable grain boundaries enabled ultrafast grain growth across the bonding interface, analyzed via coincidence site lattice (CSL) boundaries using EBSD. Above 125 °C, the Σ3 boundary length exceeded 40%, while below 120 °C it rapidly declined, transforming into Σ27a, indicating a critical transition dominated by the {115} plane. A temperature-time-dependent grain growth model was developed, incorporating CSL effects. Simulations showed grain evolution and timing of CSL boundary formation, with transition times from 316 to 190 s as temperature increased.Scientific reports30978https://www.ebi.ac.uk/biostudies/studies/S-EPMC12373834biostudies-literatureGrain boundary motions of low temperature and low pressure copper to copper direct bonding by electroplating ultra-fine-grain (UFG) Cu.PMC12373834Chen PYCheng TYHuang YCLin KCHuang WCChang JSLee YFSu YCLin CLChiu CYLiu CYChiu CWYang LHHsieh HCYu ZYLo MHPan SALin CHHsu CEfalseGrain boundary motions of low temperature and low pressure copper to copper direct bonding by electroplating ultra-fine-grain (UFG) Cu.Cu-Cu direct bonding using electroplated ultrafine-grain Cu (107.24 nm) was studied in air at 110-150 °C. Unstable grain boundaries enabled ultrafast grain growth across the bonding interface, analyzed via coincidence site lattice (CSL) boundaries using EBSD. Above 125 °C, the Σ3 boundary length exceeded 40%, while below 120 °C it rapidly declined, transforming into Σ27a, indicating a critical transition dominated by the {115} plane. A temperature-time-dependent grain growth model was developed, incorporating CSL effects. Simulations showed grain evolution and timing of CSL boundary formation, with transition times from 316 to 190 s as temperature increased.2025-01-01T00:00:00Z2025 Aug2026-05-03T03:08:40.308Z2026-05-03T03:06:00.253ZS-EPMC123738344084712910.1038/s41598-025-17058-2