I had a play with a piece of printed circuit board sitting flat copper side down on the surface of the etchant It was connected to a tiny variable speed motor which made the board orbit. While the refresh rate was fast It etched the board twice as quick around the edge and hardly etched in the centre, not successful at all. My thoughts at the time was to try a linear motion but never go around to it
Craig VK2ZCM
----- Original Message -----
From: Stefan Trethan
To: Homebrew_PCBs@yahoogroups.com
Sent: Sunday, April 27, 2008 7:50 PM
Subject: Re: [Homebrew_PCBs] Re: etch tank idea
I'd say it would probably work in a vertical tank, but moving the PCB
would add complexity to the holder.
Uniformity is rotten in my tank too, especially since some of the
holes in the bubbler hose seem to deteriorate over time leaving a few
powerful streaks of bubbles. I'm sure it takes as much time again to
complete the board as it takes to etch the first few spots bare, if
not more. That sounds awful, but with the stuff i do (usually no
smaller than 8mil) it doesn't seem to be a problem.
If there is a way to improve it, without too much fiddling about, i'd
surely impement it. I was thinking about replacing the hose with a
artificial stone type bubbler. Those seem to give better uniformity.
ST
On 4/27/08, Adam Seychell <a_seychell@...> wrote:
>
> Interesting. I wonder if this concept could be made to work in a
> vertical tank. The PCB could be mounted to an plastic shaft that is
> attached to some cam assembly at moderate speed. The circular
> displacement might only be several mm , but the agitation could prove to
> be uniform and vigorous. I assume any mechanical method would add a lot
> of complexity, machining up bushes, wheels, brackets, et.
>
>
> A cover plate is mandatory for bubble agitation since splashes go all
> over the place otherwise. I found the cover plate also needs to have a
> neat fit and recessed slightly so run off goes back into the bulk solution.
>
>
> Adam
>
>
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