Abstract
The development of fifth-generation (5G) communication and wearable electronics generates higher requirements for the mechanical properties of copper foil. Higher mechanical properties and lower resistance are required for flexible copper-clad laminate and high-frequency and high-speed Cu foil. Deep cryogenic treatment (DCT), as a post-treatment method, has many advantages, such as low cost and ease of operation. However, less attention has been paid to the impact of DCT on rolled Cu foil. In this study, the effects of DCT on the microstructure and mechanical properties of rolled Cu foil were investigated. The results show that as the treatment time increased, the tensile strength and hardness first increased and then decreased, reaching a peak value of 394.06 MPa and 1.47 GPa at 12 h. The mechanical property improvement of rolled Cu foil was due to the grain refinement and the increase of dislocation density. The dislocation density of rolled Cu foil after a DCT time of 12 h was determined to have a peak value of 4.3798 × 1015 m−2. The dislocation density increased by 19% and the grain size decreased by 12% after 12 h DCT.
Highlights
Rolled copper (Cu) foil is widely used in various fields such as communication [1], energy [2,3], and transportation [4] due to its excellent conductivity, ductility, electromagnetic shielding, and corrosion resistance
Advanced mechanical properties of Cu foil are required to adapt to the development of 5G communication [8], wearable electronics [9], and new energy vehicles (NEV) [10,11]
It was found that the reduction of defects caused by Deep cryogenic treatment (DCT) jeopardized the mechanical properties of the alloy, which can be improved by the aging process
Summary
Rolled copper (Cu) foil is widely used in various fields such as communication [1], energy [2,3], and transportation [4] due to its excellent conductivity, ductility, electromagnetic shielding, and corrosion resistance. Compared to the conventional heat treatment (CHT), DCT positively impacted the microstructure, making martensitic laths become sharper, smaller, and more oriented Despite this progress, the effects of DCT on the surface chemistry of treated materials are still unclear. It was found that the reduction of defects (dislocations and stacking faults) caused by DCT jeopardized the mechanical properties of the alloy, which can be improved by the aging process. The effects of DCT on the microstructure, mechanical, physical, and chemical properties of rolled Cu foil are studied. The mechanism of mechanical properties improvement is proposed by investigating the microstructure, corrosion resistance, and dislocation density
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