Homebrew PCBs

Dwayne,
Did you find the Ammonium Persulfate to have a short life for production
work? I did not use it because of the life of the mixture. Was just
wondering about your experience with it.
-Mike

----- Original Message -----
From: "Dwayne Reid" <dwayner@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, April 26, 2003 10:49 AM
Subject: Re: [Homebrew_PCBs] Homemade PCB holders for etcher


> At 09:18 PM 4/14/03 -0700, luther m stroud wrote:
> >I tried verticle etch with cucl and it was't even faster near the bubbles
> >from the bottom that at the top . stainless steel may not last in the
> >etchant .
>
> The PCB holder arrangement I described has been working well for at least
> 15 years - that is about the age of the holders I described.  However, I
> use ammonium persulphate catalyzed with sulfuric acid as my etch
solution -
> clean and effective.  My etch tank is welded stainless steel, as is the
> immersion heater used to heat the etchant - both of these have been in
> regular use for about 20 years.  We used to just hang the boards in the
> etcher before I made the holders.
>
> Vertical bubble etch is somewhat slower than a spray etcher but there is a
> lot less mess and it was cheap to build.  This was a very important
> consideration back when we built our PCB etch system.
>
> The air source is a very compact blower (something like a vacuum cleaner
> motor) obtained from a local surplus outlet (Princess Auto) years ago.
The
> sparging tubes are drilled PVC - 2 tubes that form a "U" in the bottom of
> the tank.
>
> I've been told that the reason bubble etch works so well with ammonium
> persulphate is the constant agitation and the continuous addition of
oxygen
> to the etch solution.  We pretty much followed Clyde Coombs PCB Handbook
> and it just works.
>
> dwayne
>
> --
> Dwayne Reid   <dwayner@...>
> Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
> (780) 489-3199 voice          (780) 487-6397 fax
>
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