For what it's worth, I've been using Cool-Amp silver plating powder for a little while on my pcb's now, it's so much easier than any chemical tin plating I've heard of. Previously I was using a hot solder pot (solder in a frypan on a camping oven) using a windscreen squeegee to level the solder. Worked great but not the safest, what with lead fumes and spitting hot molten solder and all.
But yeah, the cool amp is as simple as tapping a little bit of powder onto freshly etched copper, putting a drop of water down on it and rubbing it into the copper (i use my finger). In a minute or two it's silver plated.
Admittedly silver does get tarnished etc so not as easy to solder if you leave it a while, but if I'm making a pcb I'm using soldering it pretty soon in which case it's great.
I don't think I'm getting any surface leakage like this suggestion, I used it on an fpga board that's running at 90Mhz and haven't seen anything to cause concern.
Andrew
On 13/09/2010, at 4:36 AM, Malcolm Parker-Lisberg wrote:
> It does deposit tin on the FR4 surface, and will prove problematic if you have high impedance circuits, it also causes problems when the board is conformally coated, with tin migration under the coating.
> Conformally coating the board first and then applying the tin is a better solution for high impedace or low leakage PCB requirements.
> It should not be a roblem with normal home PCB CMOS circuits.
>
> Malcolm
>
> I don't suffer from insanity I enjoy it!
>
> --- On Sun, 9/12/10, designer_craig <cs6061@...> wrote:
>
> From: designer_craig <cs6061@...>
> Subject: [Homebrew_PCBs] Re: Again on tinning!
> To: Homebrew_PCBs@yahoogroups.com
> Date: Sunday, September 12, 2010, 6:49 PM
>
>
>
> Not to worry, this electroless tin solution works by a redox reaction with the copper and does not deposit any tin on the epoxy. I used it for years and never had any surface leakage issues. As with any material its important to wash the board completely to make sure you remove any ionic salts from any microscopic pores and fishers on the material surface.
>
> Craig
>
> --- In Homebrew_PCBs@yahoogroups.com, Alessio Sangalli <alesan@...> wrote:
>
> >
>
> > Hi, I was about to place an order for the precision scale and the
>
> > chemicals needed for tinning but:
>
> >
>
> > - I use the H2O2 + HCl method for etching
>
> >
>
> > What was not clear from the thread that was going on several weeks ago,
>
> > is if it can be used after etching the PCB and if it delivers a good
>
> > result. Somebody reported it may create a layer of high impedence on the
>
> > board; as my applications can be low-power electronics to SMPSs, I do
>
> > not really like to deal with such "problem".
>
> >
>
> > The tinning method I am referring to is the one explained here:
>
> > http://www.voodooengineering.com/index.php/pcbprocess/tinning
>
> >
>
> > And I was going to order the chemicals from:
>
> > http://shop.ebay.com/quartzpegmatite/m.html?_nkw=&_armrs=1&_from=&_ipg=&_trksid=p4340
>
> > as suggested by bebx2000
>
> > Thiourea 98% Lab Chemical One Pound --> $11.99
>
> > Stannous Chloride Anhydrous 98% 1/4 lb --> $8.99
>
> > Sulfamic Acid 99.8% Lab Chemical One Pound. --> $5.99
>
> >
>
> > What to do? I'm quite confused.
>
> >
>
> > bye
>
> > as
>
> >
>
> [Non-text portions of this message have been removed]
>
>
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