ELECTROLYTIC COPPER FOIL, NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERY, LITHIUM ION SECONDARY BATTERY, RIGID PRINTED CIRCUIT BOARD, AND FLEXIBLE PRINTED CIRCUIT BOARD

摘要

PROBLEM TO BE SOLVED: To provide an electrolytic copper foil in which tensile strength is not so reduced by even heat treatment at high temperature applied in the production of a rigid printed-circuit board, a flexible printed-circuit board or a lithium ion secondary battery, having excellent handling properties, and further, capable of obtaining a satisfactory cycle life in the case a lithium secondary battery is composed used as the current collector of a negative electrode.SOLUTION: Provided is an electrolytic copper foil containing carbon by 150 ppm or higher, chlorine by 200 ppm or higher and sulfur by 50 ppm or lower as impurities in the foil, in which ordinary tensile strength is 450 MPa or higher, and tensile strength measured at ordinary temperature after heating at 450°C for 1 hr is 350 MPa or higher.SELECTED DRAWING: Figure 1