It may have gotten more expensive over time.? It was about 30 USD for a pint the last time I bought it, and it does have some nasty stuff in it.? It does work well on a clean board, though.
One method of making PC boards was to put down a layer of positive photoresist over a bare board, expose it with a positive of the artwork so that when developed, copper would be exposed where you wanted there to be a track.? You'd then electroplate tin on the board, strip the resist and etch it.? You would have to use something like ammonium persulphate, which does not attack tin. Regular Ferric chloride and CuCl etchants will not work.
If you were making double sided boards with plated through holes you'd drill the holes first, dunk the board in a graphite solution, plate one ounce of copper over that, then add resist and etch as normal.? The tin plating would also cover the inside of the plated through holes.
Haven't used any of these, I did toner transfer for double sided boards, stitched top and bottom together, with the top and bottom boards being half thickness and produced separately.
Harvey
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On 11/1/2020 4:57 AM, Tony Smith wrote:
I never tried tin plating PCBs, from memory the stuff was expensive, hard to
get and went "off" quickly. Seemed like a lot of hassle for little reward,
I just sprayed boards with clear lacquer.
Out of curiosity I looked up chemical tin plating, and of course ENIG comes
up. The 'N' is nickel, and the 'G' is gold. Explains why it's expensive I
guess.
The other type of chemical nickel plating is a nickel phosphor coating, not
good for PCBs but ok for machinery parts.
It's occurred to me that if you were into milling PCBs you could
electroplate the copper board beforehand. I wonder if anyone does that.
Tony
-----Original Message-----
From: [email protected] <[email protected]> On Behalf
Of Dave
Sent: Friday, 30 October 2020 1:58 AM
To: [email protected]
Subject: Re: [homebrewpcbs] RoHS question
Tony,
? I tinned some of my first home made pcb's but never again. And the
boards
I ordered are of the ENIG variety. No rocket science comes out of my
hobby.
:)
On 10/28/2020 3:08 PM, Tony Smith wrote:
Yes, we're in violent agreement.
Unless you're a manufacturer, RoHS (or whatever your local flavour is)
isn't a problem.
Space vehicles are exempt from these regulations, I guess they figure
not many of them are going to wind up in a landfill. For the tin
whiskers, the problem wasn't lead-free solder, it's the tin plating on
the copper tracks, something even hobbyists do. I think they nickel
plate stuff like spacecraft PCBs now.
Dunno if there is a chemical solution to do nickel plating on copper
like you do with tin, but electroplating nickel is really easy.
Tony
