Homebrew PCBs

JanRwl@... wrote:
> Can someone here PLEASE outline the procedure and chemistry to  use for this 
> etch-method?  I have never seen ANYWHERE a list like, 
> "1.  Boil the bare blank in swamp-water;
>   2.  Incant;
>   3.  Swish the board around in a 30% CuCl solution  over 80\ufffdC for 15 minutes;
>   4,  Etc. etc."
>  
> With FeCl, you can omit steps 2. and 4., and the result is  fine, but messy.  
>  
> Please?
>  
> 

There's  two main approaches to chloride etching chemistry.

1) CuCl2 + HCl + H2O2
2) CuCl2 + HCl + O2

Method 1)is much faster than 2). I use 2) at room temp, which is about 2 
to 3 times slower than FeCl3 at same temperature. For 1) you don't 
actually need CuCl2, but helps, and its a byproduct so you get it for 
free. Most reliable determination of CuCl concentration is by density 
measurement, and should be 1.30 to 1.45 g/cm^3, yes, very concentrated 
solution needed for method 1), or else its too damn slow. HCl should 
also be > 1 Molar (4% wt) for speed. Ball park figure of HCl content is 
easily found by taking a 1cm^3 graduated diabetic syringe filled with 
1.0 cm^3 of 40g/Liter NaOH. Add drop wise to small clear jar filled with 
1.0 cm^3 sample from etchant + 1 table spoon of water. When copper 
hydroxide precipitate forms, stop, stir, and continue additions if 
precipitate redissolves. When precipitate stops dissolving then HCl 
concentration = X Molar, where X is cm^3 of NaOH solution added. You 
need access to some scales measurable in gram units in order to prepare 
40g/L NaOH solution.