Relationship between microstructure and etching performance of 12 μm thick rolled copper foil

Abstract

12 μm thick rolled copper foil is the thinnest rolled copper foil that can be stably produced at present, which can be used for the production of high-end Flexible Printed Circuit (FPC) boards. With the miniaturized and multi-functional of various electronic components in the age of 5th Generation (5G) communication, higher requirements have been put forward for the etching performance of rolled copper foil. The microstructure of 12 μm thick rolled copper foil was obtained through thermal treatment at 180 °C for different times, and then the relationship between microstructure and etching performance was systematically studied. The research results show that the etching performance of rolled copper foil improves with the increasing of annealing time. But the etching performance of copper foil annealed for 10 min is better than that annealed for 30 min. Due to the low energy of Low Angle Grain Boundaries (LAGBs), the etching performance of copper foil gradually becomes better with the decreasing of LAGBs proportion. The etching performance of copper foil improves with the decreasing of work-hardening and dislocation density. The lower proportion of {001} crystal planes is the key reason for higher etching rate. The etching performance of copper foil is better with higher Random High Angle Grain Boundaries Network (RHGBN). The amount of grain boundaries decreases with the increasing of grain size, resulting in the decreasing of etching performance. In addition, it is found that the release of residual compressive stress on copper foil surface can also obviously improve the etching performance.

Keywords

• Rolled copper foil
• Microstructure
• Etching performance
• Dislocation density
• Residual compressive stress