Homebrew PCBs

>From: "Dave" <wa4qal@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Re: Etch safe materials for etch tank
>Date: Thu, 09 Dec 2004 16:01:00 -0000
>
>
>
>--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
>wrote:
> > Phil wrote:
> > >
> > > about acrylic - the guys at TAP Plastics told me that it is not acid
> > > resistant.  I wouldn't use it for CuCl because of that.  It worked
> > > fine for AP and FeCl, though.
> > >
> > > Phil
> > >
> > The three above mentioned etchants normally have acid and pH will be
> > very low (< 1). Acrylic (PMMA) is ok for acid. I made a small
> > electrochemical test cell out of this stuff and have had 20% sulfuric
> > acid in it for weeks at a time and see zero effect to date.
> >
> > Nylon is the common plastic you must avoid contact with acid for long
> > periods, even vinegar.
> >
> > Of course there is always www.google.com
>
>Nylon is definitely no good in a FeCL3 etch bath.
>
>Years ago, I had the brilliant idea that, instead of moving the
>etchant, I'd move the board instead (Think of this as sort of a
>Mohammed and the Mountain analogy.).  So, I used one of the index
>holes in the board to tie a section of nylon monofilament fishing
>line to the board, and could jiggle the board with that, thus
>achieving agitation (Think clock drive or something like that
>eventually.).  Only, the nylon monofilament line didn't
>even last for one etch before it broke.  Oh, well, back to the
>drawing board.

There was a design in the ARRL Handbook a few years back for an etching 
arrangement that simulated hand agitation by using an eccentric cam on the 
shaft of a geared-down motor to rock the container. The etchant was kept hot 
with a heat lamp positioned above the container.

Leon