| 摘要 |
PROBLEM TO BE SOLVED: To provide a rolled copper foil excellent in strength and conductivity, and also excellent in a roughening treatment.SOLUTION: A rolled copper foil contains 0.5 to 1.0 wt.% Co, and 0.12 to 0.3 wt.% Si, a mass ratio of Co to Si being 3.5≤Co/Si≤5.0, and the balance comprising inevitable impurities and copper. When observing a cross section in a direction parallel to the rolling direction, an average grain size of crystal grains of a plate thickness direction is 300 nm or less. When observing the surface, among precipitates including Co and Si, the number of small sized grains of the average grain size 100 nm or less is 50 grains/μmor more, the number of medium sized grains of the average grain size 100 nm or more and 1,000 nm or less is 5 grains/μmor less, and the number of large sized grains of the average particle size more than 1,000 nm is 10 grains/mmor less. |
