Homebrew PCBs

I'm guessing, drawing on high school and college chemistry.

H2O2 + HCl + Cu -> 2H20 + CuCl
Unreacted H2O2 and HCl remain in solution.

HCl + NaOH -> NaCl + H2O

You are very unlikely to produce H2O2 in the reaction with HCl and NaOH, 
IMO.

My guess is that you have CuCl as the blue sludge.  I suppose it could 
be CuOH, but you'd have to convince yourself that Cu would rather bond 
with OH.  A smell of chlorine when you are reacting would be a clue, or 
bubbles and a yellow gas.

pcb.easy wrote:
> I design my own boards using positive acting pre-sensitized boards.
>
> My developer solution is made of 1/2 teaspoon Sodium Hydroxide in 
> 300ml water.
>
> My etch solution is made up of 1 part 31% Hydrochloric acid (HCl), 
> and 2 parts 3% Hydrogen Peroxide (H2O2).
>
> The above chemical solutions work very well for me, and are extremely 
> fast. I'm not looking to find a better way. I am looking to reduce 
> the waste that goes to the hazard waste facility.
>
> I'm not a chemist, didn't even take high school chemistry. Anyway 
> here is an experiment I did with the above chemicals, to try and 
> reduce the amount of waste. 
>
> Safety first, wear chemical goggles, gloves, apron, and work in a 
> well ventilated area 
>
> Hydrochloric acid (HCl) is very acidic, PH1. Sodium Hydroxide (NaOH) 
> is very alkaline, PH14. When you mix an acid with an alkaline and 
> adjust the solution to PH7 they become table salt and water.
> HCl + NaOH = NaCl + H2O2
>
> It takes a lot of Sodium Hydroxide to move from PH1 to PH2, but it 
> takes very little to move from PH6 to PH7. And if the solution is 
> very alkaline it takes a lot of Hydrochloric acid to move from PH14 
> to PH13, and very little to move from PH8 to PH7.
>
> I mixed the spent etchant and developer together and started to 
> neutralize the mixture. At about PH6 what I believe to be copper 
> chloride started to precipitate out of solution. After the solution 
> had set for about 12 hours, a blue sludge had formed at the bottom of 
> the container and what I believe to be saltwater solution was at the 
> top. 
>
> I siphoned off most of the water being careful not to disturb the 
> sludge.
>
> I tested the PH of the water that had been removed from the sludge 
> container and it is still approximately PH7, and is crystal clear.
>
> I have reduced the 3 liters of chemicals down to less than 250ml of 
> sludge. 
>
> Am I on the right track? 
> Is the blue sludge copper hydroxide?
> Can the sludge be reduced even more by drying?
> If so how can it be safely dried? 
> Is there an issue storing copper hydroxide in powder form?
>
>
>
>
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