Electrolytic copper foil

Abstract

Provided is an electrolytic copper foil having a surface roughness Rz of 2.0 μm or less, wherein a foil thickness difference in the width direction is 1.5% or less. Also provided is the electrolytic copper foil, wherein the foil thickness difference in the width direction is 1.3% or less. Further provided is the electrolytic copper foil, wherein a variation in the roughness in the width direction (Rzmax−Rzmin)/Rzavg is 15% or less. An object of the present invention is to provide an electrolytic copper foil having low surface roughness, wherein the formation of an “elongation wrinkle” and a discolored streak along the length direction is suppressed by allowing the thickness to be uniform in the width and length directions.

1 . An electrolytic copper foil having a surface roughness Rz of 2.0 μm or less, wherein a foil thickness difference among sixteen places in a width direction is 1.5% or less, the electrolytic copper foil is cut at both ends in the width direction by 20 mm and folded four times and divided into sixteen to measure the foil thickness difference in the width direction, no discolored streak is present along a length direction on a surface of the copper foil, and an elongation wrinkle is not developed. 
     
     
         2 . The electrolytic copper foil according to  claim 1 , wherein the foil thickness difference among the sixteen places in the width direction is 1.3% or less. 
     
     
         3 . The electrolytic copper foil according to  claim 1 , wherein a variation in the roughness in the width direction (Rzmax−Rzmin)/Rzavg is 15% or less. 
     
     
         4 . The electrolytic copper foil according to  claim 1 , wherein the foil thickness difference among the sixteen places in the width direction is 0.89% or less. 
     
     
         5 . The electrolytic copper foil according to  claim 4 , wherein a variation in the surface roughness in the width direction (Rzmax−Rzmin)/Rzavg is 15% or less. 
     
     
         6 . A method of manufacturing an electrolytic copper foil, comprising the steps of:
 flowing a copper electrolytic solution between a rotating cathode drum and an anode opposed to the cathode drum to allow copper to be electrodeposited on a surface of the cathode drum;   providing a supplementary split anode only along a front side of the drum;   individually controlling an amount of electricity provided to each of a plurality of split anodes of the supplementary split anode, the plurality of split anodes being separated in a width direction of the drum; and   detaching an electrodeposited copper foil from the cathode drum.   
     
     
         7 . The method according to  claim 6 , wherein the electrodeposited copper foil is produced such that the copper foil has a surface roughness Rz of 2.0 μm or less and a foil thickness difference across the width direction of 1.5% or less, and no discolored streak is present along a length direction on a surface of the copper foil. 
     
     
         8 . The method according to  claim 7 , wherein the foil thickness difference in the width direction is 1.3% or less. 
     
     
         9 . The method according to  claim 8 , wherein a variation in the surface roughness in the width direction (Rzmax−Rzmin)/Rzavg is 15% or less. 
     
     
         10 . The method according to  claim 7 , wherein a variation in the surface roughness in the width direction (Rzmax−Rzmin)/Rzavg is 15% or less.