Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

fwiw, here is the cleaning procedure that I have used
successfully
for over 20 years...

1) Scrub board with the scour-side of 3M kitchen-sponge and
liquid dish-detergent. Can't recall the 'grade' name of the
sponge
(they make 3), but it's the agressive one....has a 'scratchy'
feeling.

This step removes oils, greases, and debris. Important first
step.


2) Microetch board for 15-60 seconds in a weak solution of
sodium persulphate....or a weak sulfuric-peroxide solution works
very good also.

Ferric Chloride is not really suitable for this task. By using
the
clear-solution etchants, one can see the color of the copper
change before your eyes; from the typical "orange" look, to the
true reddish color of 100% pure clean non-oxidized copper.

It happens in just a few seconds. I generally swish the board
around a bit in a little plastic tray while watching it.

When it's obvious that the whole surface has been microetched
to pure reddish copper; I rinse, blow dry with an air-gun (100psi

from compressor tank), and take it right to the laminator for
applying dry-film resist.

I.e., don't let it sit around for 3 days and oxidize again.

I would think that this clean-then-microetch procedure would
work equally well for toner-transfer processes. The microetch
-guarantees- a clean surface because it makes the old surface
go away! <grin>
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