Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
>
> On Tue, 10 Jan 2006 00:09:31 +0100, alan00463 <alan00463@y...> wrote:
> 
> > Sure, Adam.   I want to etch the copper artwork *before* I have all
> >
> > the components to populate the board with.   So that is why I wanted
> >
> > some substance to cover the copper traces immediately after etching so
> >
> > they don't become oxidized.    I was thinking it would be easier to
> >
> > solder the (through-hole) components in place if I used an
> >
> > electrically conductive material.   Or should I use something I can
> >
> > later clean off the copper traces with solder flux when ready to
> >
> > populate the board?
> 
> 
> There's a much easier option.
> Buy a can of solder laquer spray. It is a laquer made mostly of
colophony  
> resin and alcohol.
> It takes a while to dry, but overnight it is hard and dry to the touch.
> 
> This _is_ flux, so soldering is easy even after a long time.
> Unless you are dealing with extremely high impedance circuits you can  
> leave it on for protection even after soldering.
> 
> 
> Much quicker than any plating, cheaper, and easier to solder. I use
it all  
> the time.
> 
> 
> And yes you are right, conductivity of plating can be important. For  
> example with high frequency the plating can actually increase
resistance  
> of a track because skin effect drives half the current out into it.
At low  
> frequency this does not happen.
> 
> ST

Adam, you're right--I DON'T KNOW WHAT I'M DOING.    That's probably
why I sounded contradictory and confusing.    That's why this newbie
appreciates your comments and helpful advice.

Stefan, good note about the skin effect with high frequency signals!
I was thinking more in the line of transparency--i.e., how do I know
if the coating has been removed if it is transparent?   I needed your
comments based on experience.  I am grateful for your sharing your
knowledge.  Thank you.

I will look for "solder lacquer spray".   Nearly all the websites that
mention are in the U.K.   Maybe it's called something different in the
U.S.A.     I am wondering if this is the same stuff you would buy in a
paint store in the U.S.A. for protecting wood?    Or is it something
different?   I couldn't find it in Mouser, Digikey, or JameCo
catalogs, even looking under the generic heading "chemicals".   

The closest I found was "silicone  conformal coating" and "urethane
conformal coating".   These are anti-fungal, anti-moisture coatings
for protecting the circuitry from harsh environments.   Probably not
what you had in mind.

Stefan, the "solder lacquer spray" you use is transparent, is it not?
Does acetone dissolve it once it has hardened?   Can you see where it
has been removed vs. where it remains on the copper?

I will try to find this lacquer before I give up and buy the silver
electroless plating powder.

Later,
Alan