Re: etching without chemicals
Posted: 02 May 2009, 14:07
Ok, I won't bother with strong chemistry here (the title of the topic shows I'm OT), but from the equations and values, here's what happening:
Peroxyde "sees" two reactants: chloride ions (from the chlorhydric acid) and copper. The values in the tables indicates that the copper reaction is done far more easily than the chloride one, which is good for us (peroxyde will mostly interact with copper). The green color appearing is due to copper chloride...
BUT the chloride reaction happens at all times, and produce chlorine gas, which is extremely harmful. So I haven't tested it yet, but do prepare your etchant short before etching, and don't leave it around you when the PCB is removed, cause it will continue. The two reactions need protons (H+ = acidity), so if you spill your etchant in a big bucket of water, pH will rise to almost 7, and these H+ ions won't be enough to let the reaction happening fastly... I bet the quantities of copper chloride produces aren't big, but I still have to look if it's not too bad for environment...
I hope this helps and avoids intoxications, event if it's off topic
Be safe, fellas!
Peroxyde "sees" two reactants: chloride ions (from the chlorhydric acid) and copper. The values in the tables indicates that the copper reaction is done far more easily than the chloride one, which is good for us (peroxyde will mostly interact with copper). The green color appearing is due to copper chloride...
BUT the chloride reaction happens at all times, and produce chlorine gas, which is extremely harmful. So I haven't tested it yet, but do prepare your etchant short before etching, and don't leave it around you when the PCB is removed, cause it will continue. The two reactions need protons (H+ = acidity), so if you spill your etchant in a big bucket of water, pH will rise to almost 7, and these H+ ions won't be enough to let the reaction happening fastly... I bet the quantities of copper chloride produces aren't big, but I still have to look if it's not too bad for environment...
I hope this helps and avoids intoxications, event if it's off topic
Be safe, fellas!