Homebrew PCBs

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.

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!!.

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

My local plastics guy says plexiglass is not good for constant contact
with water. It will absorb some and swell, causing crazing.

Steve Greenfield

> On Wed, 22 Jun 2005 07:30:50 +0200, Ray Dinwiddie  
> <crdinwiddie@e...> wrote:
> 
...
> > Etchant Tank: Plexiglas pipe 1/8 side wall, any diameter you want,
> > available at any local glass shop that advertizes plexiglas. ...

--- In Homebrew_PCBs@yahoogroups.com, "Steve" <alienrelics@y...>
wrote:
> My local plastics guy says plexiglass is not good for constant
contact
> with water. It will absorb some and swell, causing crazing.

This is true. Here's a simple but long duration experiment.
Fill a 8x10" (approximate) tray (polyethylene is good) with
water (half full) and place
a piece of acrylic plastic (3mm thickness is good) over it like
a lid. The acrylic sheet needs to cover the entire tray and should
overhang a little on all sides. The sheet is not in direct 
contact with the water. Note flatness of plastic at start of
experiment.
Leave undisturbed in a normal room environment for two weeks or
so. At the end of this period note warpage of acrylic plastic.

The observed warpage is due to water absorbtion on the bottom
surface.