I switched from ferric chloride to sodium persulphate (MG Chemicals). It is a much easier to handle are requires somewhat less care.
I often etch single PCBs in a glass bread pan sitting on a foam rubber block while read mail. A slight rocking of the pan is enough to keep the etchant moving. I heat the etchant to about 130 degrees prior to starting. Depending on how worn out the etchant is I may have to reheat.
One of these day I should make a real etching tank.
The heavier the copper is the more you will have undercutting. This post on Electrotech has some images of a PCB I was working on a while back. Compare the edges to what you are getting.
http://www.electro-tech-online.com/chit-chat/86683-cricut-2.html#post674243 --- On Thu, 6/25/09, jc805sb <jc805sb@...> wrote:
From: jc805sb <jc805sb@...>
Subject: [Homebrew_PCBs] Re: “Dragon’s Blood” resin reduces undercut?
To: Homebrew_PCBs@yahoogroups.com
Date: Thursday, June 25, 2009, 3:58 AM
Yes thanks - I got all the Pulsar stuff recently and have
finished etching 2 boards using the starch paper and the
Green laminating paper. Also I got the pulsar-recommended
laminator which is amazing, I should have tried it sooner.
The results so far look much better esp. using the
Green plastic, the resulting copper is very solid, no
pock marks. Though the edges are quite jagged.
I am using HCl + H2O2 etchant and have so far not tried
the sponge method. My etch times are definitely too slow
considering these are very small boards.
>
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