Homebrew PCBs

On Fri, 15 Mar 2013 18:29:06 -0700, you wrote:

>wow!
>
>You dudes play around with some very nasty stuff just to etch a printed 
>circuit!

The three most common chemicals are:

1) ferric chloride.  may or may not be readily available, electronics
wise, hard to find.  Last price I saw was USD 30/gallon and that was
many years ago.  It's ferric chloride and some HCL.  Main problem with
it is opacity, lack of regeneration, cost, and it stains everything in
sight.  Use it warm.

2) xxx persulphate, generally potassium or ammonium persulphate. Needs
to be used warm.  Clear and turns into blue clear as it etches, one
source is pool chemicals, but only 32% is active ingredient and the
rest is "additives".  It will work, but a batch in the tank that I
have costs 10 USD/session and I don't think it lasts. 

3) copper chloride:  start off with drugstore H2O2 and muriatic acid.
As long as you handle the acid well, there's no problem that I've
seen.  Once the H2O2 goes flat (with etching and with time), you have
CuCl etchant which lasts practically forever.  Regenerate with HCL,
use with bubbled air and use warm.  Cost?  Perhaps 5 USD/gallon or so,
and considering that it lasts forever, I'd say a good choice.

I used ferric chloride for years, I can show you stained driveways to
prove it.  

I switched over to the copper chloride (probably cupric chloride, but
I don't pretend to be a chemist) a while back and will avoid the
ferric chloride from now on.

I'd use the persulphate etchant if I could get a decent supply of the
chemical, it would be a "use once" and discard.  Not sure exactly how
to get rid of it, though.  Problem is not the etchant, it's the copper
in the etchant.

just my opinions, though.

Harvey

>
>Or, maybe this thread is just a sort of "pissing contest" to show off that
>the participants have had Chem 101 at a community college.
>
>Pardon my  cynicism, but I just don't get the drift.
>
>Keep it simple..........keep it safe.
>
>Roland F. Harriston, P.D.
>***************************
>
>On 3/15/2013 4:16 PM, smilingcat90254 wrote:
>>
>> Calcium carbonate for that matter most carbonate will react with even 
>> trace amount of hydrochloric acid remaining in your etchant. And yes 
>> it will foam because CO2 is being released in the reaction. So if your 
>> solution keeps foaming keep adding the carbonate. It will neutralize 
>> the acid for safe disposal.
>>
>> Reaction of Copper chloride and Calcium carbonate probably will be 
>> much slower than Copper chloride and sodium carbonate. But it should 
>> work. not 100% plus sure.
>>
>> **** HF acid ****
>> I was in semiconductor manufacturing business so I'm quite aware of HF 
>> acid. Very dangerous stuff. No you can not store in a glass. It will 
>> etch glass. No you can not store in stainless steel container!!
>>
>> HF chemical burn is severe even at low concentration. It will 
>> penetrate bare skin and the flourine ion will interact with the 
>> calcium in your bone. HF will dissolve your bone under all the tissue.
>>
>> I didn't think you can buy it unless you can show you are a business 
>> or a researcher of some sort.
>>
>> 
>
>
>
>[Non-text portions of this message have been removed]