Rolled Copper Foil and Manufacturing Method of Rolled Copper Foil

Abstract

A rolled copper foil, according to the present invention, obtained after a final cold rolling step but before recrystallization annealing includes a group of crystal grains which exhibits four-fold symmetry in results obtained by X-ray diffraction (XRD) pole figure measurement with respect to a rolled surface. In the XRD pole figure measurement, at least four peaks of a {220} Cu plane diffraction of a copper crystal due to the group of crystal grains exhibiting the four-fold symmetry, which is obtained during β axis scanning with an α angle set to 45°, appear at intervals of 90°±5° along the β angle.

1 . A rolled copper foil obtained after a final cold rolling step but before recrystallization annealing, including a group of crystal grains which exhibits four-fold symmetry in results obtained by X-ray diffraction pole figure measurement with respect to a rolled surface, wherein:
 at least four peaks of a {220} Cu  plane diffraction of a copper crystal due to the group of crystal grains exhibiting the four-fold symmetry, which is obtained by axis scanning with an α angle set to 45°, appear at intervals of 90°±5° along the β angle.   
     
     
         2 . The rolled copper foil according to  claim 1 , wherein:
 the diffraction peaks exhibiting the four-fold symmetry at intervals of 90°±5° along the β angle each have a diffraction intensity at least 1.5 times stronger than a minimum intensity of {220} Cu  plane diffractions of the copper crystal, which are obtained by the β axis scanning.   
     
     
         3 . The rolled copper foil according to  claim 1 , wherein:
 when normalized intensity of the {220} Cu  plane diffractions of the copper crystal in results obtained by the X-ray diffraction pole figure measurement with respect to the rolled surface by the β axis scanning at respective α angles are plotted on a vertical axis with the α angle on a horizontal axis, the maximum value P of the normalized intensity appears in the range of the α angle from 25° to 35°; the maximum value Q of the normalized intensity appears in the range of the α angle from 40° to 50°; the normalized intensity increases monotonically in the range of the α angle from 85° to 90°; and the maximum value P, the maximum value Q, and the normalized intensity R at an α angle of 90° have a relation of “Q≦P≦R”.   
     
     
         4 . The rolled copper foil according to  claim 1 , wherein:
 in results obtained by X-ray diffraction 2θ/θ measurement for the rolled surface, diffraction peak intensity of a {200} Cu  plane of the copper crystal is equal to or greater than that of the {220} Cu  plane of the copper crystal.   
     
     
         5 . The rolled copper foil according to  claim 1 , wherein:
 the rolled copper foil further includes another group of crystal grains which exhibits four-fold symmetry in results obtained by X-ray diffraction pole figure measurement with respect to the rolled surface; and   at intervals of 90°±10° of the β angle appear the {220} Cu  plane diffraction peaks due to the another group of crystal grains exhibiting the four-fold symmetry, which are obtained by the β axis scanning within the range of 40° to 50° of the α angle.   
     
     
         6 . A rolled copper foil obtained by applying a recrystallization annealing to the rolled copper foil according to  claim 1 , wherein:
 the rolled copper foil has a relation of “[A]×[B]×[C]≧0.5”, where [A] is a cubic texture ratio calculated from results by X-ray diffraction 2θ/θ measurement for the rolled surface, [B] is an out-of-plane alignment ratio calculated from results by X-ray diffraction rocking curve measurement for a crystal grain with the cubic texture, and [C] is an in-plane alignment ratio calculated from results by X-ray diffraction pole figure measurement for the crystal grain with respect to the rolled surface.   
     
     
         7 . A rolled copper foil to which a recrystallization annealing is applied after a final cold rolling step, wherein:
 the rolled copper foil has a relation of “[A]×[B]×[C]≧0.5”, where [A] is a cubic texture ratio calculated from results by X-ray diffraction 2θ/θ measurement for a rolled surface, [B] is an out-of-plane alignment ratio calculated from results by X-ray diffraction rocking curve measurement for a crystal grain with the cubic texture, and [C] is an in-plane alignment ratio calculated from results by X-ray diffraction pole figure measurement for the crystal grain with respect to the rolled surface.   
     
     
         8 . A manufacturing method of a rolled copper foil, wherein:
 the rolled copper foil obtained after a final cold rolling step but before recrystallization annealing includes a group of crystal grains which exhibits four-fold symmetry in results obtained by X-ray diffraction pole figure measurement with respect to a rolled surface in which at least four peaks of a {220} Cu  plane diffraction of a copper crystal due to the group of crystal grains exhibiting the four-fold symmetry, which is obtained by β axis scanning with an α angle set to 45°, appear at intervals of 90°±5° along the β angle; and wherein:   one or more rolling passes in a second rolling pass and later in the final cold rolling step have a working ratio at least 1.1 times greater than an immediately preceding rolling pass.   
     
     
         9 . The manufacturing method according to  claim 7 , wherein:
 a final pass or a pass immediately before the final pass in the final cold rolling step has the largest working ratio per pass through the second rolling pass and later.   
     
     
         10 . The manufacturing method according to  claim 7 , wherein:
 a total working ratio in the final cold rolling step is 80% or more and less than 90%.   
     
     
         11 . A manufacturing method of a rolled copper foil, wherein:
 the rolled copper foil obtained after a final cold rolling step but before recrystallization annealing includes a group of crystal grains which exhibits four-fold symmetry in results obtained by X-ray diffraction (XRD) pole figure measurement with respect to a rolled surface in which at least four peaks of a {220} Cu  plane diffraction of a copper crystal due to the group of crystal grains exhibiting the four-fold symmetry, which is obtained by β axis scanning with an α angle set to 45°, appear at intervals of 90°±5° along the β angle; wherein:   when normalized intensity of the {220} Cu  plane diffractions of the copper crystal in results obtained by the XRD pole figure measurement with respect to the rolled surface by the β axis scanning at respective α angles are plotted on a vertical axis with the α angle on a horizontal axis, the maximum value P of the normalized intensity appears in the range of the α angle from 25° to 35°, the maximum value Q of the normalized intensity appears in the range of the α angle from 40° to 50°, the normalized intensity increases monotonically in the range of the α angle from 85° to 90°, and the maximum value P, the maximum value Q, and the normalized intensity R at the α angle of 90° have a relation of “Q≦P≦R”; wherein:   when, in results obtained by the XRD pole figure measurement with β axis scanning at respective α angles with respect to the rolled surface of the rolled copper foil obtained after an annealing step for green sheet but before the final cold rolling step, the normalized intensity of the {220} Cu  plane diffractions of the copper crystal are plotted on the vertical axis with the α angle on the horizontal axis, the maximum value Q of the normalized intensity appears in the range of the α angle from 40° to 50°, the minimum value S of the normalized intensity appears in the range of the α angle from 20° to 40°, and the maximum value Q and the minimum value S have a relation of “2≦Q/S≦3”, this type of rolled copper foil being used as an annealed green sheet; and wherein:   a total working ratio in the final cold rolling step is 80% or more and less than 93%.