PURPOSE: To form an excellent tin hot-dipping film without requiring a flux treatment by executing a drawing treatment prior to a plating treatment or, furthermore annealing treatment under specific conditions at the time of subjecting the surface of a copper wire to tin hot dipping.
CONSTITUTION: The copper wire 3 is continuously drawn out of an un-coiler 1 at ≥400m/min line speed and is subjected to the drawing treatment at >50% reduction rate of area to increase the surface area of the copper wire 3, by that, the copper oxide film on the surface of the copper wire is finely crushed and the pure copper surface is exposed. The copper wire is passed, at need, through an annealing furnace 5 of a non-oxidating atmosphere, by that, the work strains generated during the drawing are relieved without reoxidizing the surface. The copper wire is then passed through a tin hot-dipping bath cell 7 and the excess molten tin sticking to the copper wire is removed by a drawing die 8; thereafter, the copper wire is coiled by a coiler 2. The copper oxide on the surface of the copper wire which is the blank material is finely crushed during the drawing and the pure copper surface is exposed and, therefore, the hot dip tin plated copper wire consisting of the pure copper wire of the core wire, the copper-tin alloy layer on its surface and the pure tin layer is produced at a good yield without using the flux for removing the copper oxide.
NAKATSU AKIYOSHI
KAWAGUCHI KOICHI
WATANABE TOKIO
