JanRwl@... wrote:
>
> In a message dated 3/29/2006 2:24:48 A.M. Central Standard Time,
> stefan_trethan@... writes:
>
> I'm not sure the tinnit and other electroless stuff would make a thick
> enough plating to work as resist.
>
>
>
> Correct.
>
It has not to do with tin plating thickness, but chemical reactivity.
Tin will react with all acidic copper etchers that I know of. That is
why anyone who wants to etch a PCB using tin as a metal etch resists
must use an alkaline based copper etchant. The higher the pH the more
stable tin metal becomes. A common alkaline etchant is the ammonia
chloride types used by most of the PCB fabricators in the world.