Homebrew PCBs

Adam, yes I know what you mean about the vertical hobbyist kit tanks. The
air holes are spaced too far apart in them. Actually, I did try a homemade
horizontal bubbler once. The bubbles would not move across the copper evenly
and caused areas of the copper to etch faster than others. In some cases the
bubbles would stay in one place and cause the etchant to not react with the
copper.
 I used a vertical tank that I built like a fish aquarium only much thinner.
It was made of glass panels and was sealed with the same RTV material used
for aquariums. I made it wide enough so that I could get one hand down to
the bottom so that I could perform maintenance when needed. It was tall
enough to hold 12X12 panels, to give you an idea of dimensions. The air for
the bubbler was provided by a small compressor, although other means will
also work. About the bubbler: In fish stores you can find cheap devices to
create a wall of tiny bubbles in your fish tank. I used a few of these glued
(RTV) onto the bottom of the etch tank. On mine, I had to use a small needle
and poke a few larger holes to get something better than a mist. These
devices are made of some type of cardboard material, so it is easy. A very
even layer of holes provide a wall of bubbles that produce very good results
on the panels. Some experimentation here is needed the first time.

Mike

----- Original Message -----
From: "Adam Seychell" <adam_seychell@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, April 21, 2003 8:07 PM
Subject: Re: [Homebrew_PCBs] Re: Cu + HCl -> CuCl2 : part 3


> Hi Mike , welcome to the list. The ferric chloride is well know
> among DIY PCB etching. The air regenerated CuCl2 etching is new
> to me and seems like a nice etchant once understood how it
> behaves. This is why I've been working out ways of producing it
> from copper metal and HCl, both are cheap and easily available
> (two key rules for us hobbyist). It turns out to be very easy to
> prepare your self and quite tolerant to varying operating
> parameters, such as free HCl, and Cu content. Theoretically it
> can etch 2 sq.ft of single sided 1 oz PCB materal per liter of
> solution before needing readjustment with acid and water.
>
> I'm interested in methods of getting a uniform etch across the
> board. I've tried several different vertical bubble etch tanks
> and I'm not happy with etch consistency. Have you tried floating
> the PCB and hit it with bubbles ?
>
> Adam