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From: Robert Baer
X-Mailer: Mozilla 4.75 [en] (Win98; U)
Subject: Re: Etching!
Date: Fri, 18 Oct 2002 23:20:29 GMT
NNTP-Posting-Date: Fri, 18 Oct 2002 16:20:29 PDT
Organization: EarthLink Inc. -- http://www.EarthLink.net
"Märt Pikkani" wrote:
> I don't know if this is rihgt newsgroup to get my answer but i will try. If
> not, then could anyone recomend me a newsgroup from where i could get
> Here is what i did.
> I printed out my PCB on to a tranparency. Then used money detector as UV
> light an got tracks onto board. With NaOH (developer fluid) the tracks
> became clear and visible.
> Then used Fe3Cl to etch the Cu around the tracks.
> tracks are still with clear and visible but Problem is that Cu around the
> tracks changes its color( like Pink) but doesn't leave the PCB clear.
> Meaning that all the plate is still covered with Cu but little Cu has left
> the PCB. I could feel the edge of the track with my finger.
> What is my problem?
> is it money detector (UV ligth), which I don't believe.
> Do I do something wrong?
> Is it problem of etching bouder?
> Märt Pikkani
You may have ruined the FeCl with the base; (1) do not use any base
The etching solution (a) did not work long enough, or (b) was "killed"
by the NaOH; you may have seen a "scum" on the surface, one indication
of the second possibility.
Add a very slight amount of acid (HNO3 is best, but use sparingly) to
prevent the FeCl from "turning".
FeCL etches perferentially on the Cu crystals, so the copper *will*
turn from bright copper to dull red (allowing you to "see" the traces);
ammonium perchlorate etches uniformly and the copper may seem to get
cleaner as it works.
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