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Newsgroups: sci.environment
From: (Bruce Hamilton)
Subject: Re: Environmental impact of PCB Etchant (FeCl3?)
Date: Thu, 21 Mar 1996 05:52:54 GMT

In article <4ij3at$> (David Kammeyer) writes:

>I have recently taken an interest in electronics, and am about to transfer
>some of my designs from breadboards to PCBs.  I recently purchased an
>etching kit, including a ~.4l bottle of Ferrus Chloride (?).  I have heard
>that this is bad to put down the drain.  Can someone tell me the impact of
>this chemical and how best to dispose of it, and what my alternatives are?
>If it matters, this is far from a high volume operation.  I will proably be
>etching less than 5 small boards per month, for a possible total volume of
>5l or so per year.

I used to prepare a ferric chloride etchant for our electronics people, but
it used to die fairly quickly, even just on storage.

Then I found a recipe on Usenet several years ago, and they have used
that successfully since. The original recipe was 250 ml of 5% hydrogen
peroxide in water is carefully mixed with 50 ml of concentrated hydrochloric
acid. Use fresh and warm slightly if necessary. I changed the concentrations
so they could use equal volumes, thus reducing the acid fumes from the
concentrated HCl ( although increasing the H2O2 concentration probably
had some disadvantages.

     Bruce Hamilton

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