An acid sulfate electroplating tin bath is very safe, as it only
contains sulfuric acid and tin(II) sulfate, plus some proprietary
non-toxic organic plating additives. Let me know if you want the
exact bath makeup described on the additive data sheet
There many other tin electroplating baths, which as you say
contain nasty stuff. This is the reason I chose the sulfuric acid
tin(II) sulfate bath for plating my PCBs. But of course
electroplating is not suitable for your application unless you
can connect every PCB trace to the negative terminal of the power
supply.
Electroplating solutions are almost everlasting, so there is
much less disposal than immersion tin. Electroplating also is
highly predictable and reliable because the quantity of tin
deposited is directly related to the total electrical charge from
the power supply. The finish of electroplated tin is much easier
to control than immersion tin, making it possible to obtain
bright mirror like finish. In addition, the chemical running
costs are only tiny fraction, even considering initial bath makeup.
Use immersion only when you cannot make electrical contact with
the metal.
mpdickens wrote:
> Wouldn't this
>
>>allow for less
>>dangerous chemicals
>>than electroless plating?
>
>
> Your kidding, right?
>
> The Metal Finishing Guidebook lists three formulations
> for immersion deposits of tin onto copper, only one
> formula is free of really nasty stuff. Here is that
> formula:
>
>
> Stannous chloride 3.8 g/L
> Thiourea 49.5 g/L
> Sulfuric acid 12 ml/L
>
> Combine the compounds at a temperature of 80-120
> degrees Fahrenheit.
>
>
> The TINNIT crystals are more than likey a solid
> formulation of the above because this is the only
> formula that is not deadly poisionous. Electroplating
> ANYTHING. produces nasty stuff that has to be disposed
> of.
>
> If I were going to plate tin onto a pcb, I'd use the
> TINNIT crystals: They are premixed, cheap and not as
> hard on the environment as the by-products produced by
> electroplating.
>
>
> Best regards
>
>
> Marvin Dickens
> Alpharetta, Georgia USA
>
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