Surface treatment process for copper foil
AssigneeMitsui-Anaconda Electro Copper Sheet Co., Ltd.
InventorsShigeyoshi Morisaki, Nobuo Kitamura
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Abstract
A process is disclosed for preventing oxidative coloring while maintaining good solderability of copper foil wherein a thin layer of tin or a combination of tin and zinc alloy is electro-deposited on the surface of the shiny side of copper foil and the tin or binary alloy diffuses into the surface portion of electrodeposited copper foil by heating, such as drying, baking or lamination under heat and pressure. By virtue of an extremely thin layer of the tin alloy thus formed, the bright tone of the copper surface is maintained during storage or during subsequent lamination of the foil, and the solderability thereof is also improved.
Claims5
A process for the surface treatment of copper foil, comprising electrodepositing, in an alkaline bath containing more than 0.3 g. of Sn/l, at a current density of from about 1 to 3 A.multidot.sec/dm.sup.2, on a shiny metallic side of copper foil a thin layer of tin to the extent that the whitish color of the deposited tin is minimized and the reddish color of the copper surface is maintained, followed by heating the foil so produced to diffuse said tin layer into the copper layer and thereby to produce a thin layer of tin and copper alloy.
Dependencies are inferred from the claim text.