| 摘要 |
PROBLEM TO BE SOLVED: To uniformize the surface, to reduce the surface roughness without using toxic elements and to impart sufficient adhesive strength with a resin by subjecting the surface of copper foil to cathode electrolysis in an electrolyzing bath of copper sulfate contg. aluminum and titanium in the vicinity of the critical current density to roughen the surface and next executing copper plating and rust preventing treatment. SOLUTION: Untreated copper foil is subjected to acid cleaning, after that, at least one side is subjected to cathode electrolysis in an electrolyzing bath of sulfuric acid or copper sulfate contg. Al ions and Ti ions in the vicinity of the critical current density or above to precipitate the projections of copper, and surface roughening treatment is executed. On the surface-roughened copper foil, plating by copper or a copper alloy is film-formed, and after that, rust preventing treatment is executed. The concn. of Al ions and titanium ions in the elements to be added to the electrolyzing bath is preferably controlled to 0.03 to 5.0 g/l. The time for the cathode electrolysis is desirably controlled to 10 to 50 deg.C, and the current density to 5 to 100 A/dm2, and the electric quantity is suitably controlled to 20 to 200 coulomb/dm2.
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