Most boards are finished with a solder coating to protect the copper from oxidation. This could be plated and then reflowed or by hot air leveling. I always preferred the hot air leveling method. The board was dipped in a flux and then immersed in molten solder for a second or so. As it was removed from the solder, hot air jets blew the excess solder back into the molten bath. It had several advantages over the plating method. The alloy content was assured to be eutetic and there was little chance of having so much solder that the solder mask would chip off during wave soldering.
For home brew applications the best bet for protecting the circuitry is to use a conformal coating applied after the board is assembled. Most of these products can be applied as a spray coat after protecting any DIP switches and contact areas with a masking tape.
----- Original Message -----
From: Bob Weiss
To: Homebrew_PCBs@yahoogroups.com
Sent: Monday, October 18, 2004 7:16 PM
Subject: [Homebrew_PCBs] Re: Green coating used on PCB's
Thanks for the answers...I thought it was something you could do at
home but I guess not. What does one use to protect the copper when
your finished with the board? Tinning?
--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell
<a_seychell@y...> wrote:
> Bob Weiss wrote:
>
> >
> > Does anyone know what they use on PCB's to give that green
coating
> > that they then apply silkscreening to? Can this be purchased? IF
so
> > where? What are the benefits to using this?
> >
> >
>
> Google: "soldermask"
>
>
http://www.rockwellcollins.com/about/additionalproducts/collinsprinte
dcircuits/page1823.html
>
> Normally applied as a film and exposed/developed much like etch
resists
> except this stuff never comes off. Older methods would silk screen
> soldermasks, newer methods use Inkjet technology to print directly.
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