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Copper curcuit board


I’m not making jewlery- yet- but right now I’m making circuit boards
(copper), which also use ferric acid. I’ve gotten some acid that’s
sopposed to work in about twenty minutes, less if heated. My current
rig is a plastic tray 5x9x2, and I suspend a 60 watt trouble light a
few inches above it. I put the curcuit board (3x4 1/2) in, then cover
it in the acid and agitate it. 4 1/2 hours and a full bottle of acid
(16 oz) later, the circuit board is yet undone. I have done this
several times, trying different things, replacing the bath several
times in some trys, without lights, with stronger lights, agitating
softly, vigurusly, in cercles, and, inevatably at the end of each try,
flying through the air in multable peices. No one try has gone under 2
hours. I’ve tryed diferent resists; enamels, commercal resist pen, and
varnish. The acid I’ve used is a “PCB etchant solution,” from Radio
Shack, containing FeCl3. I also tryed some merric acid. I don’t know
what I could be doing wrong, and whatever tips and suggestions you can
give me (except quit, don’t know what that means) would be greatly
appreciated. Thanks for your time.


Did you lightly sand the circuit board before applying your pattern?
Some circuit boards have a coating on the board to stop the copper
from oxydizing until it is used…neccesitating the need to remove
the coating before doing anything.

Hope this helps.
Daniel Grandi


Hmmmm, I have used the same stuff from Radioshack to produce dozens
of boards in the past. It always worked fine. Perfect boards in
just a few moments, no heat required…Many PC boards come with a
coating to prevent oxidation while in storage. Before you lay out
your board, use fine steel wool to buff it to a high gloss. This
should get rid of the coating, and allow the ferric chloride to get
to the copper.

Michael Turley


Ive had lots of luck with the radio shack stuff, I wonder whats going
wrong?! Ive used Permanent felt markers for resist, and
Asphvaltum(sp) I usually put a layer of electrician’s tape on the
back. The etching surface must be facing down, and not touching the
bottom of your tray, so usually I stand it on balls of plasticine
(very technical). I probably agitate every 30 minutes, with no heat
source. Its not fast, but in 3-4 hours I have a good etch… karen in vancouver


Try acidifying the PCB etchant. Ferric chloride is an acidic salt.
You can speed up the etching process with an acid. Muriatic acid
[aka Hydrochloric acid] is sold in most masonary supply stores. But
do be careful with ventilation and take care of your skin and eyes!
I would prefer to increase the strength of the acid instead of
heating. When my students did the etching with FeCl3 is often took
better than a class period [45 minutes]. The acid is more aggressive
but may also not give you an even cutting if you are not agitating
the solution [ie moving the bubbles along].



Various things can affect the ferric chloride. Was your solution
commercially prepared as a liquid? Or was it granular form, which you
then mixed with water? Sometimes, if you haven’t thoroughly cleaned
and rinsed the copper, you may not have removed all of the resist
present on a substrate type of electronic board. There may be a thin
film of laquer, varnish or plastic on the copper side which must be
removed first. The etchant may be reacting with some of your cleaning
agents to neutralize the solution. I always clean the copper first so
it will be bright and shiny, then wash thoroughly (Ajax dish soap here
in the U.S. has a high concentration of surfactants), rinse thoroughly
until I see a “sheeting” action of the water, then finally wipe down
with rubbing alcohol.

Other factors that affect the etching are the use of tap water, which
often contain mineral contaminants, the strength of the solution, and
the smut buildup. Always use distilled water when making a solution
from crystals. Check the strength of the solution with a Baume
hydrometer. Most of my etching is done in the 15-25 degree range.
Baume hydrometers can be found photo supply shops. Smut is the residue
left when etching that is the dissolved metal and the ferric chloride.
You have to keep removing this smut with a brush or feather to expose
the surface of the metal to the etchant.

You may contact me offline if you need further help. K.P. in WY