https://www.cas.cn/syky/202604/t20260413_5106724.shtml

https://www.science.org/doi/10.1126/science.aed7758

Breaking the “Impossible Triangle”: Researchers Create Super Copper Foil

Copper foil is as a key conductor in integrated circuit interconnects and a core substrate for lithium battery. It must not only withstand complex mechanical loads but also have high conductivity, high thermal conductivity, and long-term thermal stability.

Researchers from the CAS Institute of Metal Research have developed a copper foil that combines ultra-high strength, high conductivity, and excellent thermal stability.

Using a novel “gradient ordered structure” microstructure design as the core, they formed high-density nanodomains on a 10-micrometer-thick copper foil nanocrystal matrix with a purity of 99.91% by employing trace amounts of organic additives during the electrolytic deposition process, meeting industrial-scale requirements. These nanodomains have an average size of only 3 nanometers and exhibit a nanoscale “gradient ordered structure” with alternating “poor” and “rich” distributions along the thickness direction of the copper foil. The resulting “gradient ordered structure” nanodomain copper foil boasts a tensile strength of up to 900 MPa, surpassing the strength limit of conventional copper foils.

Simultaneously, the copper foil maintains a conductivity of 90% IACS, approximately twice that of copper alloys with equivalent strength. After nearly six months at room temperature, its performance showed no degradation. This breaks the “impossible triangle” of difficulty in simultaneously achieving strength, conductivity, and thermal stability in copper foil.

The synergistic improvement in the performance of this new copper foil stems from the dual ordered structure effect of nanodomains both between and within the grains. In the horizontal direction, the uniformly distributed nanodomains between grains suppress strain localization, enhancing the overall uniform deformation capability of the material. In the vertical direction, gradient-distributed nanodomains induce ultra-high density of geometrically necessary dislocations, achieving strengthening. In particular, when the ultra-high density, extremely small nanodomains form a semi-coherent interface with the matrix, they pin grain boundaries, inhibiting grain growth, and, due to their extremely weak electron scattering effect, ensure the high conductivity of the copper foil.

This research  provides a novel design approach for the fabrication of high-performance copper foil.