Tin coating of copper by hot dip process

A. Hi cousin Venkatesha. Briefly, you probably need to bright dip the wire, then clean and flux it before tin dipping. I imagine you will also need to reflow the tin after dipping, and a chromate anti-tarnish step might not be uncommon.

We thank you for visiting finishing.com, and we don't want to give you a hard time ... still, you have asked a series of very broad general questions that fill whole textbooks, and we can't write such a book for you in reply; all we can do if refer you to them

So please see if the tin associations in your area have any booklets available that will help you get started. And try to visit a hot dip tinning shop. Please talk to the equipment suppliers about the treatment cycles. Try to get a book or two about hot tin dipping if you can. Good luck.

A. Hi, Animesh.

I could easily be in error, but I don't think there is any one particular "standard thickness for tin coated wire for industrial purposes". But you can measure the thickness a few different ways including x-ray fluorescence for thin deposits and a micrometer/caliper for thicker ones.

Wire is often drawn to thinner diameters after plating, rather than being plated at final diameter, and this could lead to different plating thicknesses depending on the draw-down ratio, too. Good luck.

Regards,

A. Hi Mahesh. I've only seen one or two hot-dip tinning lines for copper wire so I am no expert, but I can readily envision a tendency for the deposit to become tear-shaped in cross section as the melted tin droops by gravity from the horizontal copper wire. It may be that a lower tin temperature, or getting the wire vertical sooner and for longer would help.

I've seen ceramic donut spools to wipe away excess tin but I'm not sure they will actually contribute to concentricity.

Regards,

A. Use freshly drawn clean wire.

Run it over a felt pad which is soaked with flux, then through the molten tin, followed closely, while the tin is still molten, through tight holes in asbestos,/Teflon tape, several thicknesses. Speed should be 100 - 1000 fpm, faster for smaller sizes.

The tin must be continuous and smooth. There is no thickness requirement since it is for solderability only.

Molten tin will be some temperature above 450 °F. At that temperature, annealing of copper will be almost instantaneous to full soft condition.

You can electroplate tin onto copper, no problem.