Effects of deformation and applied temperature on the microstructure and performance of industrial ultra-thin rolled Cu foil

Five-generation communication, foldable cell phone, and wearable devices promote the development of Cu foils by applying multi-layer printed circuit board (MLPCB) and flexible printed circuit board (FPCB). However, few research focused on the combined influence of processing, defects (dislocation, stacking faults, and grain boundaries), and textures modification and its effects on applied performance evolution in the electronic circuit board of ultra-thin Cu foil. In this paper, 12 μm Cu foils were fabricated by the rolling process at reduction deformations of 93.3% and 95.2%. The low-temperature annealing process was utilized to simulate the application of printed circuit boards. The results show that the dislocation density is significantly decreased after annealing, but the influence of reduction deformation has no changes and the dislocation density of the samples with large deformation increased by 40%. In addition to defects, grain orientation has a significant influence on copper foil properties. With the increase of brass and S textures, the tensile strength increased 28.5%. Moreover, the high index of grain plane of S, R, and {025}<001> improves the corrosion resistance by about 130.7%. This work has great significance for preparing high-performance Cu foil applied in PCB.