Now, tell me who is right?
Marvin Dickens says electroplating tin chemicals are dangerous,
Adam says no.
I didn't think I was kidding.
You know my knoweledge is very poor about chemistry
but i really thought electroLESS plating is much more complicated
and needs much more dangerous chemicals.
I did electroplating (ok, only "copper plating" with coppersulphate)
once and thought i understand the process.
Adam, you are right with "connect every track first", this
would be needed if you etch first.
(I was told this is how they make the gold plating on ISA/PCI and similar
board edge connectors.
I was told the pcb is initially a bit longer and all pins are shorted
on this extension. after gold plating this small piece is simply cut off.
(you can actually see the ends of the tracks running down to the edge at
some cards))
BUT if you plate your board BEFORE etching you don't need this.
simply make a NEGATIVE film/exposing/developing and then electroplate.
the tin should only be deposited where there is no resist.
then strip off the resist and etch.
(some etchants don't etch tin, but you can also mask with gold)
I'm not sure if this would result in a reasonably thick tin plating.
or if the surface of the tin would be "ugly" black (this happens if you dip
solder
in hcl/h2o2 etchant but i think sulphuric acid works)
I would appreciate to know which "salt" is needed for tin plating.
as sayd i used copper sulphate once for copper plating, but have no idea
which salt of tin there is.
Also i wonder which "organic additives" there are. had no idea.
st
gold plating would also be interesting - but the electroplating liquids for
gold plating
i saw at a electronics supplier were VERY expensive.
On Fri, 14 Nov 2003 12:14:45 +1100, Adam Seychell
<
adam_seychell@...> wrote:
> 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.
>
>
>