On Wed, 22 Jun 2005 07:30:50 +0200, Ray Dinwiddie
<
crdinwiddie@...> wrote:
> Hi all a new member, just found your group, thought I would share
> some on my recent discoveries re; homemade PCBs.
>
> Etchant: I use muratic acid (Ace Hardware) 1 part, Hydrogen Peroxide
> (Walgreens) 2 part, heat to 130 F, agiate with air, and dissolve 1
> Sq. In. single sided copper board per 1 oz. of etchant mix in about
> 20 sec. Advantages; cheep $.10 per oz.; very quick; clear, you can
> see the copper vanish; safely dispose of 8oz. in 2 gal. of water
> down the potty, and most importantly the hot quick action seems to
> elimiate the pitting of the copper that a slower etchant bath
> produces. Disadvantage: this solution saturates quickly and 1"
> single sided board per oz of solution is close to the satuation
> point, beyond which further etching ceases.
Heating the solution is a pretty bad idea, because you get a huge amount
of HCl vapor that is REAL BAD to anything around.
HCl doesn't have a fixed boiling point, but already below 50C it will
produce huge amounts of fumes.
safely dispose down the potty, must disagree. The 2 gal of water at best
protect your drainpipes, the sewage treatment plant still doesn't like the
copper. better bring to proper waste collection facility.
If you etch that fast, you have WAY too much H2O2. You will see serious
amounts of chlorine fumes, which are toxic. You should not see any bubbles
forming all by itself in a proper etchant.
My suggestion: Learn how to do a proper job and how to maintain this
etchant at a reasonable operation point (see CuCl etching links). Then you
will also be able to regenerate it and not need to put it down the drain.
Been there, done what you did, found it is no good.
>
> Etchant Tank: Plexiglas pipe 1/8 side wall, any diameter you want,
> available at any local glass shop that advertizes plexiglas. Heat
> the pipe in the kitchen oven at 250 F for 15 min. and strech it over
> a wooden (1x4,1x6,2x4 etc) mandrel to form a oblong tube. When cool
> pound out the mandrel. The tube shoud be about 2" longer that you
> want the finished tube, so that you can cut off about 1" at each end
> to remove the heat damaged ends. Cement the tube upright on a piece
> of 1/4 plexigal sheet to form a base. The glue is the universal PVC
> glue (Ace Hardware). Airate, with 1/4 clear PCV pipe plugged at the
> end and perforated with a hot needle, aquarium air pump or
> compressor, make a value by folding the air hose and pinching the
> fold together at the exact spot with a clothes pin. Heat the tank
> with a household heat lamp. Do the job outside!!.
>
The stretched tube idea isn't bad.
For those who can't get plastic pipe you can make a tank out of glass, is
easier to cut too. glue with silicone.
You will not have to go outside with a properly maintained etchant.
ST