Rick,
FWIW I gave up tinning the boards after I started using this
http://www.rapidonline.com/Tools-Equipment/PCB-flux-spray-30093so my process is now
print toner transfer on laser printer
use laminator to fix toner to board
chill in water
remove carrier paper
etch
(The boards can be stored indefinitely at this point)
drill (easier to see the holes when the toner is still on the board)
clean off toner with stainless wire wool or 260 wet and dry
rinse and dry with paper towels
spray on flux as above
(the boards can be stored indefinitely at this point
assembly
spray boards with acrylic sealant
I did some tests and although it is recomended to wash off the flux before coating with conformal coating, I didn't find it made much difference to longevity of the boards in automotive environment.
Chris
--- In Homebrew_PCBs@yahoogroups.com, "Rick Sparber" wrote:
>
> I was playing around with some scrap pieces of circuit board I etched and
> drilled in order to find a way to simulate the HASL (Hot Air Solder
> Leveling) process. This process puts down a very thin coat of solder over
> the copper. The solder protects the copper plus makes soldering in
> components easier.
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> I found that I could brush the board with flux. Then I built up a small bump
> of solder on the ground plane. Using my soldering iron as a paint brush, I
> dipped into the bump and then painted the copper. When done, I scrubbed the
> board with alcohol. Worked great. I had no shorted paths.
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> Rick
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