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Subject: Re: [Homebrew_PCBs] Successful TT with Pulsar paper. Tinning "mishap" with Plumbers paste.

From: "Herbert E. Plett" <cachureos@...>
Date: 2006-05-17

...
> I used the Dyna-Art paper. (They are called Pulsar, now.) Needless to
> say, this stuff has been sitting around on my shelf un-noticed for too
> long. But, I figured I should give TT a try for this small board
> (since I don't have any of the other method like EDM or CNC milling
> working - yet.)

paper works as good and is less expensive, but you already had it :)

>...and steel wool.

bad idea

>... I used moderate pressure on an iron for 5 minutes.

it's not a matter of minutes, more likely a too cold iron. you only need to
heat all up to the right temperature and 'rub' the complicated parts to ensure
good adherence. one minute or a little more should suffice

>... The etching process took over 1.5 hours.

with ferric cloride (dirty ugly stuff) at room temperature it shouldn't take
more than five minutes for a small board.
make a 'cotton swab' with a chopstick (some 1/2"x3/4" size). hold the board
vertical on a shallow plasic tray (etchant 3/8" deep) and wipe (rub softly)
with plenty etchant until you see the bare board appear, then turn it upside
down and do the rest (you first did the lower half)
easy - fast (very fast). no bubbling, no heat, no mess, no overetching...
you will quickly find out when etching takes too long (stops) and you need to
renew the exhausted etchant.

> ... I shot the board again with the hot air gun -
> just before applying the towel. I suspect the wet towel might have
> cooled the board, I mean the solder, off too quickly, so it froze in
> place, instead of wiping aside.
>
> Any hints as to what to do next?

slam the edge of the board on a hard surface while hot...
repeat on each of the four edges.




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