What is nano-twinned copper foil?

Nano-scale twinned Copper Foil, Nano-scale twinned Copper Foil, is a microstructured conductive material characterized by small porosity, fine grain size, low resistance and low stress deposited by pulse plating or electrolytic techniques. Main advantages: low electromigration (gold substitution). High conductivity and reliability. Nano-twinned copper foil will become the key material for new energy batteries, printed circuit boards and integrated chip interconnections in the future.

Variations in pulse plating parameters lead to the formation of copper foils with different microstructures. As the frequency decreases and the duty cycle increases, the nucleation rate of copper increases and the grain size in the cross-section decreases. The decrease in oriented grains with increasing pulse on-time is due to the increase in biaxial stress in the copper film, which leads to minimization of the strain energy density, thus driving the growth of oriented grains. The twin crystals not only played a role in stress relief, but also stabilized the microstructure of the copper film and improved the strength of the copper foil. This result suggests that a high density of twins in the copper microstructure will improve the reliability of microelectronic interconnect devices. The addition of thiourea to the pulse plating solution changed the nucleation mode of copper deposition from transient nucleation to progressive nucleation mode, leading to an increase in the number of nucleation sites for copper deposition. At the same time, the bias of thiourea at copper grain boundaries hindered the growth of copper grains during deposition and refined the grain size. There are more reports on the process methods and the role of additives, but there are fewer studies on the combination of pulse and DC electroplating methods. Combining the advantages of the long-term stable output current of DC and the higher deposition rate of pulsed current, copper foils with low profiles and high strength or elongation can be prepared.

The tensile strength of nanotwinned copper foils is much higher than that of ordinary electroplated copper foils. For example, it has been reported in the literature that the tensile strength of nano-twinned copper material can reach up to 700MPa, while the tensile strength of ordinary electroplated copper material is usually not more than 250MPa. In addition, nano-twinned copper foil also shows good electrical conductivity, and its room-temperature conductivity is comparable to that of oxygen-free high-conductivity copper, which makes it have a wide range of applications in the fields of electronics, communications and energy. In the field of lithium-ion batteries, nano-twinned copper foil, as a composite collector material, can significantly improve the energy density and cycle life of the battery. As the nanotwin structure can increase the specific surface area and active sites of copper foil, it is favorable for the embedding and de-embedding of lithium ions, thus improving the charging and discharging performance of the battery. Meanwhile, the high strength of nanotwinned copper foil also ensures the stability and safety of the battery during long-term use.

In addition, nano-twinned copper foil also shows great potential for application in the fields of flexible electronics, microelectronic packaging and electromagnetic shielding EMI. With the continuous development of science and technology, the requirements for material performance are getting higher and higher, and nano-twinned copper foil, as a high-performance material, will play an increasingly important role in these fields.