Electroplating after applying a resist is a good idea. That'd work just fine.
I was never keen on ammonium persulphate, as a cheapskate hobbyist the mixture didn't last, unlike ferric chloride that lasts for ages, or even better (& cheaper!) cupric chloride that you can regenerate. And it doesn't stain everything brown either.
I have used graphite to electroplate non-conductive things, that's pretty simple. Vias might be a bit fiddly.
Tony
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-----Original Message-----
From: [email protected] <[email protected]> On Behalf
Of Harvey White
Sent: Monday, 2 November 2020 3:06 AM
To: [email protected]
Subject: Re: [homebrewpcbs] RoHS question
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
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
