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Re: What is the best etching solution;

2009-04-26 by jj_winkel

>
> What is the mix for the Hydrogen Peroxide, Muratic acid for a 'proper
> mixture'? (Yea, I'm a newbie, so excruciating details are welcome.)
> 
> IHS ... Jack

Here in France it is easy and cheap enough to get "masonry" grade H202 (35% in weight or 130 in volume)used for wood bleaching and stains removal, and HCl (33%), 
so my recipe for 1 liter is : 750mL water + 50mL H2O2 + 200mL HCl in that order, etching time is about 8 to 10 minutes,
this gives time to control the etching and stop it when OK.
I have tried with less dilution, but as the solution is exothermic, it produces such a volcano and heat that fine traces can be etched thru or resist lifted before you have a chance to remove the board.  
But usually I only prepare 1/4 L (250 mL) enough for small boards everytime, as the solution cannot be kept and as it deteriorates rapidly it is best to throw it away. 
I have made a very small vertical tank by glueing two CD box covers, it contains about 200mL and I dip in boards up to 5x4" (I normally leave as much copper as possible, only etching around the traces)
JJ.

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