Equ-Axed Fine-Grained and Nanotwinned Cu with Ultrahigh Tensile Strength

High Resolution Image Download MS PowerPoint Slide In this study, the Electroplating parameters were systematically tuned to transform Cu microstructures from columnar grains into equ-axed fine grains with high-density nanotwins. The optimized electroplating parameters (0.5 M [Cu 2+ ], 49.13 ppm [Cl – ], 10 °C plating temperature, and 7.11 A/dm 2 (ASD) current density) yielded an average grain size of 0.16 μm and twin spacing of 31.7 nm. These microstructural features enabled a tensile strength of 737.5 ± 7.1 MPa in the as-deposited state and up to 828.6 ± 9.2 MPa after annealing at 100 °C for 2 h, while maintaining 70% conductivity. The complex systems response (CSR) platform served as an auxiliary multivariate optimization tool to locate the process window efficiently. By achieving simultaneous enhancement of ultimate tensile strength, this work provides practical guidance for tailoring nanostructured Cu films and foils for printed circuit boards and advanced interconnects.