Difference between revisions of "Chemical Etchants"

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Hi,
  
== Ferric Chloride ==
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This is the most common hobbyist etchant. Ferric chloride, FeCl<sub>3</sub>, is a brownish substance. It's usually sold in a bottle (dissolved in water, perhaps with a little acid or peroxide) or as a powder (which you have to dissolve in water).
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When in solution, ferric chloride is a ferric ion (Fe<sup>3+</sup>) and a chloride ion (Cl<sup>-</sup>). The ferric ion reacts with the metallic copper on the circuit board in a redox reaction, producing a ferrous ion (Fe<sup>2+</sup>) and cuprous or cupric (Cu<sup>1+</sup> or Cu<sup>2+</sup>) copper. The chlorine is just along for the ride. The copper ion, unlike the metallic copper, is soluble, so it leaves the circuit board and goes into solution. The reaction products form a black sludge which settles to the bottom of the etching tank. After etching enough copper, all your Fe<sup>3+</sup> is used up and your solution is full of Cu<sup>1+</sup>, and you need to get more etchant.
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Sincerely,
 
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Sean
== Ammonium Persulfate ==
 
 
 
== Sodium Persulfate ==
 
More environmentally friendly than ferric chloride.  Can monitor the etching as initially clear new etchant solution turns blue from the copper ions.
 
 
 
== Hydrochloric Acid and Hydrogen Peroxide ==
 
Dead simple etchant made from ordinary, store-bought chemicals. Has the advantage that it can be regenerated by bubbling oxygen/air through it, or by adding more H<sub>2</sub>O<sub>2</sub>. The used etchant also makes a great algecide/pH reducer for your pool (and a whole lot cheaper than that stuff they sell at the pool store).
 
 
 
What you need:
 
* 38% Hydrochloric Acid, HCl (available at finer pool supply stores as Muriatic Acid)
 
* 3% Hydrogen Peroxide, H<sub>2</sub>O<sub>2</sub> (available from any drug store)
 
* Plastic or Glass Pans, Jars, and tongs (no metal)
 
Directions:
 
 
 
# Mix your HCl and H<sub>2</sub>O<sub>2</sub> 1:1 in a non-metalic container, making sure to add the acid slowly to the H<sub>2</sub>O<sub>2</sub>. DO NOT ADD THE H<sub>2</sub>O<sub>2</sub> TO THE ACID!!!
 
# After you've masked your board, dip it in the solution and constantly agitate. You should notice a dark green cloud start to come from the board almost immedately which quickly dissapears or turns lighter as it gets further from the surface of the board.
 
# Etching should take about 10min depending on the temperature and how well you agitated the etchant. When all of the copper is gone, dip in water to wash off any stray etchant and stop the reaction.
 
# When done etching, save used etchant in a non-metalic container and mark clearly its contents.
 
# If your etchant has become a dark, murky green color, add a little bit of H<sub>2</sub>O<sub>2</sub> or bubble air/O<sub>2</sub> through the solution to regenerate it back to a light, transparent green color.
 
See links at bottom for more information on the chemistry and some pictures of the process.
 
 
 
== Disposal procedures ==
 
Flushing used etchant down the drain is a bad idea (and usually illegal) because copper ion is toxic. The usual recommended way to dispose of hobbyist amounts of etchant is to convert it to a solid somehow and dispose of the solid in the trash.
 
* [http://www.kepro.com/fmc4.htm Kepro Circuit Systems] Removal of Copper and Persulfate from Spent Sodium Persulfate Etchant by Precipitation
 
 
 
== External Links ==
 
* [http://www.k9spud.com/wiki/PCB:Etchants Ferric Chloride vs. Ammonium Persulfate] and other etching chemicals.
 
* [http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html Etching with Air Regenerated Acid Cupric Chloride]
 
* [http://esmonde-white.com/etching_pcb.html Etching a Copper PCB with HCl and H2O2]
 

Latest revision as of 22:04, 13 September 2022

Hi,

It's no secret that high-quality content is key to a successful online presence. But creating great content takes a lot of time and effort - time that you might not have. That's where jasperbot.de comes in. Jasper is artificial intelligence software that writes better content for your website, emails and social media. It's free to use, so why not give it a try? I think you'll be impressed with the quality of the content jasper produces - take a look at the demo and try out the demo. It's free! Check it out at http://addon-coders.de/

Sincerely, Sean