Chemical Etchants

From OpenCircuits
(Difference between revisions)
Jump to: navigation, search
(HydroChloric Acid / Hydrogen Peroxide)
 
(12 intermediate revisions by 8 users not shown)
Line 1: Line 1:
[http://mugollih.ifrance.com/comments/micrososft-office.html micrososft office 2003] [http://sheilahyap.pop3.ru/krystal-steal.html krystal steal free movie clips] [http://mugollih.ifrance.com/comments/amablescom.html amables.com] [http://pricillafarias.iespana.es/blog/john-mellencamp.html john mellencamp i need a lover lyrics] [http://gakohlera.ifrance.com/q/at-t-calling.html at t calling plan] [http://wilhelminabrock.pop3.ru/blog/about-a-boy-movie.html about a boy movie soundtrack] [http://revaschlemmer.ibelgique.com/orange-theater.html orange theater tree] [http://lorrettathornto.pop3.ru/wiki/wakemed-cary.html wakemed cary hospital] [http://www.freewebtown.com/theshywolf/body-cleansing-system.html body cleansing system] [http://genniesankey.ibelgique.com/arizona-family.html arizona family healthy] [http://genniesankey.ibelgique.com/toronto-ladyboys.html toronto ladyboys] [http://rosanabalzer.pop3.ru/view/arkansas-little.html arkansas little rental rock video] [http://harmonystrum.iespana.es/data/diamond-necklace.html diamond heart necklace] [http://raymondhanke.mystarship.com/ website] [http://zandralemke.pop3.ru/adult-male-masturbation.html adult male masturbation video] [http://sheilahyap.pop3.ru/award-award-best.html award award best critic filmfare movie] [http://zandralemke.pop3.ru/adult-internet.html adult internet movie] [http://leonasharer.ibelgique.com/library/live-odds.html live odds] [http://www.freewebtown.com/theshywolf/ifp-180t-firmware.html ifp 180t firmware] [http://sandeedoucette.pop3.ru/content/old-time-gospel.html old time gospel song] [http://sheilahyap.pop3.ru/aquamarine-movie.html aquamarine movie premiere] [http://holoaddict.ecv.vg/weskers-report.html weskers report i] [http://sandeedoucette.pop3.ru/content/1400-calories.html 1400 calorie diet plan] [http://trenaclover.iespana.es/pharmacy-champaign.html pharmacy champaign] [http://sandeedoucette.pop3.ru/content/wxdesigner-linux.html wxdesigner linux] [http://reagancapers.pop3.ru/asian-adult-videos.html asian adult videos] [http://kylieburroughs.iespana.es/guru.html guru] [http://fixnwrtr.freehoxt.com/view/eye-fact-frog.html eye fact frog red tree] [http://www.freewebtown.com/theshywolf/free-live-web.html free live web cam girls] [http://zeldagallucci.iespana.es/discount-computer.html discount computer mall] [http://lorinavanguilde.ibelgique.com/data/pen-set.html pen set] [http://trenaclover.iespana.es/juneau-alaska-airport.html juneau alaska airport travel lodge] [http://charityengelbre.pop3.ru/lib/a-civil-action.html a civil action movie script] [http://lorrettathornto.pop3.ru/wiki/cfmn.html cfmn video] [http://leonasharer.ibelgique.com/library/sdlp-leader.html sdlp leader] [http://leonasharer.ibelgique.com/library/anna-nalick-nude.html anna nalick nude pic] [http://allegratweed.freekong.cn/q/female-torture.html female torture] [http://lakenyafoerster.iespana.es/pool-table-light.html pool table light] [http://lianawhite.freekong.cn/progress-energy.html progress energy] [http://www.freewebtown.com/naryu/data/el-paso-private.html el paso private investigators] [http://cathleengillan.freekong.cn/description/dwi.html attorney dwi houston] [http://crcreek.ifrance.com/pages/amazone.html amazone fr] [http://susannalabrie.pop3.ru/article/audio-domain-download.html audio domain download free movie real.com sound] [http://nihiggs.ifrance.com/small/stop-messenger-pop.html stop messenger pop ups] [http://harmonystrum.iespana.es/data/imagxpress-professional.html imagxpress professional] [http://bonitasoukup.iespana.es/pages/internet-dental.html internet dental claims processing] [http://www.freewebtown.com/naryu/data/thongs-for-teenagers.html thongs for teenagers] [http://lorinavanguilde.ibelgique.com/data/henny.html henny penny fryer] [http://sandeedoucette.pop3.ru/content/grab-bar.html bar grab tub] [http://marcelleashford.freekong.cn/text/indoor-planter.html indoor planter] [http://tegeer.ifrance.com/new/unable-to-start.html unable to start email protection] [http://susannalabrie.pop3.ru/article/eurofighter-video.html eurofighter video clips] [http://revaschlemmer.ibelgique.com/examples-of-punnett.html examples of punnett squares] [http://sandeedoucette.pop3.ru/content/philadelphia.html philadelphia eagle sports] [http://jammiefiller.iespana.es/topic/rota-circuit-10.html rota circuit 10 wheels] [http://wilhelminabrock.pop3.ru/blog/extreme-cop-video.html extreme cop video] [http://www.freewebtown.com/theshywolf/roswell-townhomes.html roswell townhomes] [http://kennethwaggener.ibelgique.com/medical-glossary.html medical glossary] [http://www.freewebtown.com/theshywolf/akcesoria-thalia.html akcesoria thalia] [http://www.freewebtown.com/shiraikirei/view/rap-songs.html 100 rap song top] [http://sandeedoucette.pop3.ru/content/dykes.html dykes] [http://www.freewebtown.com/theshywolf/unique-halloween.html unique halloween invitation] [http://jolinebeaubien.ibelgique.com/reformed-theological.html reformed theological seminary] [http://lianawhite.freekong.cn/reich-dds.html reich dds] [http://jammiefiller.iespana.es/topic/circling-raven.html circling raven] [http://voitovicha.ecv.vg/styles/torah-bible-code.html torah bible code] [http://marinareichenba.ibelgique.com/articles/transpose-music.html transpose music] [http://harmonystrum.iespana.es/data/inuyasha-change.html inuyasha change the world midi] [http://hattiewaldrep.freekong.cn/articles/motorcycle-half.html motorcycle half helmets] [http://zandralemke.pop3.ru/alaska-find.html alaska find hunting in video] [http://nihiggs.ifrance.com/small/naturalist-beach.html naturalist beach] [http://pricillafarias.iespana.es/blog/lars.html lars] [http://susannalabrie.pop3.ru/article/jojo-video-leave.html jojo video leave get out] [http://harmonystrum.iespana.es/data/pmt-group.html pmt group] [http://kylieburroughs.iespana.es/nortel-training.html nortel training courses] [http://charityengelbre.pop3.ru/lib/joblo-movie-scripts.html joblo movie scripts] [http://frauluft.ecv.vg/web/aeromotive.html aeromotive fpr] [http://www.freewebtown.com/naryu/data/zap-fortwo-car.html zap fortwo car] [http://wynellklassen.freekong.cn/sludge-dewatering.html sludge dewatering] [http://berthahallum.pop3.ru/blog/animal-video.html animal video clip] [http://margtibbetts.iespana.es/blog/melrose-apartments.html melrose apartments urbana il] [http://gialfrey.ifrance.com/articles/kent-state-shootings.html kent state shooting 1970] [http://lorettamotto.pop3.ru/joanna-lumley-strip.html joanna lumley strip video] [http://wynellklassen.freekong.cn/beachs.html kid beach] [http://martaohare.freekong.cn/q/worms-in-cats.html worms in cats] [http://solwind.ecv.vg/content/designing-business.html designing business card] [http://laveniawilhoit.pop3.ru/pages/atkol-videos.html atkol videos] [http://wynellklassen.freekong.cn/loops.html loops] [http://www.freewebtown.com/littleshaga/pages/bell-tower-storage.html bell tower storage] [http://gilmasutcliffe.freekong.cn/resources/neuter.html spay neuter] [http://jacustriea.ifrance.com/reviews-of-antivirus.html reviews of antivirus software] [http://berthahallum.pop3.ru/blog/abdullah-king.html abdullah king video] [http://pricillafarias.iespana.es/blog/eat-man-pussy.html eat man pussy] [http://laveniawilhoit.pop3.ru/pages/jason-richardson.html jason richardson dunks video] [http://www.freewebtown.com/theshywolf/maine-bed-breakfast.html maine bed breakfast honeymoon] [http://harmonystrum.iespana.es/data/1951-pontiac.html 1951 pontiac catalina] [http://curtisbechtold.iespana.es/telugu-sex-stories.html telugu sex stories] [http://curtisbechtold.iespana.es/mannie-fresh.html mannie fresh] [http://kennethwaggener.ibelgique.com/chemist.html chemist job] [http://lanaharton.ibelgique.com/phone-service-provider.html phone service provider] [http://zandralemke.pop3.ru/adult-pic-and-video.html adult pic and video] [http://susannalabrie.pop3.ru/article/animal-image-mating.html animal image mating video] [http://bonitasoukup.iespana.es/pages/water-softener.html water softener operation] [http://magdalenefoland.pop3.ru/mest-fuct-up.html mest fuct up kid] [http://sheilahyap.pop3.ru/ati-all-in-wonder.html ati all in wonder video drivers] [http://lorrettathornto.pop3.ru/wiki/jovencitas-follando.html video de jovencitas follando] [http://www.freewebtown.com/cascadefire/romika.html romika] [http://reagancapers.pop3.ru/alone-in-the.html alone in the dark movie review 2005] [http://ncodb.ecv.vg/data/manufactured-home.html california home in manufactured sale] [http://elsiecosper.iespana.es/articles/radiant-heating.html radiant heating systems] [http://wilhelminabrock.pop3.ru/blog/autumn-grand.html autumn grand music theft video] [http://laveniawilhoit.pop3.ru/pages/kissing-girl-boob.html kissing girl boob video] [http://lorrettathornto.pop3.ru/wiki/iso-14001.html iso 14001] [http://magdalenefoland.pop3.ru/elena-hotel-islington.html elena hotel islington] [http://elsiecosper.iespana.es/articles/fun-free-online.html free fun game game girl girl online only] [http://harmonystrum.iespana.es/data/microwave-parts.html microwave parts] [http://kandismonte.iespana.es/free-adult-computer.html free adult computer game download] [http://www.freewebtown.com/cascadefire/llc-vs-incorporation.html llc vs incorporation] [http://www.freewebtown.com/cascadefire/tennessee-real-estate.html tennessee real estate commission] [http://rosanabalzer.pop3.ru/view/jay-video-z.html car in jay video z] [http://ncodb.ecv.vg/data/australian-war.html australian war medal history] [http://reagancapers.pop3.ru/evil-empire-movie.html evil empire movie] [http://www.freewebtown.com/shiraikirei/view/septal-nuclei-function.html septal nuclei function] [http://lanaharton.ibelgique.com/download-turkey.html download turkey ringtones] [http://hapinker.ifrance.com/drug-testing.html feline infectious peritonitis] [http://lorrianelesser.iespana.es/damons.html damons] [http://genniesankey.ibelgique.com/alliance-gaming.html alliance gaming] [http://laserradiation.freehoxt.com/angel-lyrics.html angel lyric] [http://www.freewebtown.com/cascadefire/mortal-kombat-movie.html mortal kombat movie] [http://www.freewebtown.com/shiraikirei/view/laval-university.html laval university library] [http://elsiecosper.iespana.es/articles/sister-in-law.html sister in law] [http://susannalabrie.pop3.ru/article/kerasote-movie.html kerasote movie theater theatres] [http://laserradiation.freehoxt.com/celeste.html celeste] [http://www.freewebtown.com/cascadefire/nomex-racing.html nomex racing suit] [http://sheilahyap.pop3.ru/imovie-convert.html imovie convert] [http://www.freewebtown.com/naryu/data/resume-writing.html resume writing] [http://hapinker.ifrance.com/tooth-blackout.html tooth blackout] [http://bonitasoukup.iespana.es/pages/psychology-classics.html psychology classics] [http://jacustriea.ifrance.com/designer-rugs.html bathroom designer rug] [http://magdalenefoland.pop3.ru/ceramic-tile-saw.html ceramic tile saw] [http://revaschlemmer.ibelgique.com/oldies-93.html oldies 93] [http://leonasharer.ibelgique.com/library/400.html form n 400] [http://wannachange.freehoxt.com/pages/newspapers-online.html the sun newspaper online] [http://allegratweed.freekong.cn/q/juvenile.html juvenile] [http://gakohlera.ifrance.com/q/grande-communications.html grande communications] [http://www.freewebtown.com/cascadefire/rachel-stevens.html picture rachel stevens] [http://www.freewebtown.com/naryu/data/off-starting.html night off right starting] [http://firesnake.ecv.vg/resources/inner-bicep.html inner bicep workouts] [http://lanaharton.ibelgique.com/toshiba-satellite.html toshiba satellite 4600 laptop] [http://graciabonneau.ibelgique.com/styles/range-hood.html stainless steel range hood] {{stub}}
+
{{stub}}
  
After masking off the parts of the copper-clad board you want to keep, you need to remove the parts you don't want to keep. This is usually done by chemically etching away the copper. There are a lot of different chemical techniques for doing this, each with its own advantages and drawbacks.
+
Chemical etching is one step of some popular [[techniques | PCB fabrication techniques]].
 +
 
 +
In this technique,
 +
* one starts with a copper-clad board.
 +
* one puts a mask over all the copper he want to keep. There are a variety of ways to do this -- see [[Toner Transfer]] and [[Photoetching]].
 +
* one removes the parts he don't want to keep, by chemically etching away the copper.
 +
* cleanup: wash off the board in the sink; carefully store or dispose of the acid.
 +
 
 +
There are a lot of different chemical techniques for doing this, each with its own advantages and drawbacks.
  
 
None of these chemicals is incredibly dangerous, but they can all be toxic or caustic, and should be treated with care. Eye protection and gloves are a very good idea. Before you start, make sure you know how dangerous each chemical is, and figure out what you will need to do if you spill it or get it on yourself. Washing with plenty of water is usually a good start. For some chemicals you may want to keep a neutralizing agent handy. An MSDS (Materials Safety Data Sheet) for the chemical will give you some basic information.
 
None of these chemicals is incredibly dangerous, but they can all be toxic or caustic, and should be treated with care. Eye protection and gloves are a very good idea. Before you start, make sure you know how dangerous each chemical is, and figure out what you will need to do if you spill it or get it on yourself. Washing with plenty of water is usually a good start. For some chemicals you may want to keep a neutralizing agent handy. An MSDS (Materials Safety Data Sheet) for the chemical will give you some basic information.
 +
 +
== vinegar and salt ==
 +
 +
* [http://www.kobakant.at/DIY/?p=2575 How to get what you want: Salt and Vinegar Etching]
 +
* [http://www.flickr.com/photos/jeanbaptisteparis/4831465916/ smt pcb with Salt and Vinegar]
 +
* [http://www.instructables.com/id/The-Saltwater-etch-process/ The Saltwater etch process]
 +
* [http://www.electro-tech-online.com/general-electronics-chat/33876-electro-etching-no-acid.html electro etching a PCB with vinegar, salt, and a 12 V power supply] (the copper etched off the PCB is plated on the anode?) -- however, other people claim that "You should not be using any acids (or basic 'acids') with your [electro] etcher at all. No FeCl no vinegar, etc ".[http://www.bladeforums.com/forums/showthread.php?t=671936]
  
 
== Ferric Chloride ==
 
== Ferric Chloride ==
 
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).
 
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).
  
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.
+
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.
  
 
== Ammonium Persulfate ==
 
== Ammonium Persulfate ==
Expensive
+
Expensive & hard to control and optimize the process parameters (such as specific gravity & pH value).
 +
 
 +
== HydroChloric Acid / Hydrogen Peroxide ==
 +
 
 +
Mixing about 1 part HCl (Which can be found at most hardware stores, also known as Muriatic Acid. Ask for concrete cleaner.) into 2 parts Hydrogen peroxide (normally used for cleaning cuts) you can make a fairly powerful etchant. Use gloves and don't breathe the fumes though. This will etch a 3"x5" board in less than 10 minutes. No need to heat it up. I usually like to drill a small hole through the board on a corner and thread a wire or nylon string through to help agitate / remove the board.
 +
 
 +
When the board is done etching, the etchant will probably look like green kool-aid, from the copper content in it. This stuff is highly corrosive and will burn skin, which is why you should wear gloves. But it is easy to handle, and fairly easy to dispose of. the etchant is easily deactivated with baking soda. Pour enough baking soda into it slowly (to keep it from boiling and overflowing... remember what happens with baking soda/vinegar? ya...) until it is a solid mass, then leave it in the sun to dry. You should contact your local authorities to find out what you should do with it next. Whatever you do, DO NOT dump the stuff down the drain, it will eat through your pipes just like any of the other etchants.
 +
 
 +
Alternatively, instead of disposing of the etchant, you can re-use it again and again. In fact, after etching a few boards with this solution, you will have successfully made [[Chemical Etchants#Acid Cupric Chloride|Acid Cupric Chloride]] (see below).
 +
You can also find a detailed tutorial on etching at [http://robotplatform.com/howto/pcb%20etching/pcb_etching_1.html Muriatic Acid etching tutorial]
 +
 
 +
== Sodium Persulfate ==
 +
More environmentally friendly than ferric chloride.  Can monitor the etching as initially clear new etchant solution turns blue from the copper ions.
 +
 
 +
== Acid Cupric Chloride ==
 +
Dead simple etchant made from ordinary, store-bought chemicals (hydrochloric acid and hydrogen peroxide). 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>. In addition, it doesn't get used up: the etchant bath simply grows with use (kind of like sourdough starter…)
 +
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 hardware stores or 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 accordance with local laws.
 +
 
 +
== External Links ==
 +
 
 +
* [http://www.instructables.com/id/Sponge-Ferric-Chloride-Method-Etch-Circuit-Bo/ "Sponge + Ferric Chloride Method -- Etch PCBs in One Minute!"]
 +
* [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] — an excellent in-depth page on acid cupric chloride etching by Adam Seychell.
 +
* [http://www.esmonde-white.com/home/diversions/etching-a-copper-pcb Etching a Copper PCB with HCl and H2O2]
 +
*[http://www.mgchemicals.com/index.html MG Chemicals]A possible source?
 +
* [http://reprap.org/wiki/MakePCBInstructions RepRap wiki: Make PCB instructions]
 +
 
 +
== Internal Links ==
 +
 
 +
 
 +
*[[Toner Transfer]]
 +
*[[Techniques]]
 +
*[[Eagle Links]]
 +
 
 +
 
 +
[[Category:Techniques]]

Latest revision as of 07:16, 26 June 2013

Chemical etching is one step of some popular PCB fabrication techniques.

In this technique,

  • one starts with a copper-clad board.
  • one puts a mask over all the copper he want to keep. There are a variety of ways to do this -- see Toner Transfer and Photoetching.
  • one removes the parts he don't want to keep, by chemically etching away the copper.
  • cleanup: wash off the board in the sink; carefully store or dispose of the acid.

There are a lot of different chemical techniques for doing this, each with its own advantages and drawbacks.

None of these chemicals is incredibly dangerous, but they can all be toxic or caustic, and should be treated with care. Eye protection and gloves are a very good idea. Before you start, make sure you know how dangerous each chemical is, and figure out what you will need to do if you spill it or get it on yourself. Washing with plenty of water is usually a good start. For some chemicals you may want to keep a neutralizing agent handy. An MSDS (Materials Safety Data Sheet) for the chemical will give you some basic information.

Contents

[edit] vinegar and salt

[edit] Ferric Chloride

This is the most common hobbyist etchant. Ferric chloride, FeCl3, 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).

When in solution, ferric chloride is a ferric ion (Fe3+) and a chloride ion (Cl-). The ferric ion reacts with the metallic copper on the circuit board in a redox reaction, producing a ferrous ion (Fe2+) and cuprous or cupric (Cu1+ or Cu2+) 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 Fe3+ is used up and your solution is full of Cu1+, and you need to get more etchant.

[edit] Ammonium Persulfate

Expensive & hard to control and optimize the process parameters (such as specific gravity & pH value).

[edit] HydroChloric Acid / Hydrogen Peroxide

Mixing about 1 part HCl (Which can be found at most hardware stores, also known as Muriatic Acid. Ask for concrete cleaner.) into 2 parts Hydrogen peroxide (normally used for cleaning cuts) you can make a fairly powerful etchant. Use gloves and don't breathe the fumes though. This will etch a 3"x5" board in less than 10 minutes. No need to heat it up. I usually like to drill a small hole through the board on a corner and thread a wire or nylon string through to help agitate / remove the board.

When the board is done etching, the etchant will probably look like green kool-aid, from the copper content in it. This stuff is highly corrosive and will burn skin, which is why you should wear gloves. But it is easy to handle, and fairly easy to dispose of. the etchant is easily deactivated with baking soda. Pour enough baking soda into it slowly (to keep it from boiling and overflowing... remember what happens with baking soda/vinegar? ya...) until it is a solid mass, then leave it in the sun to dry. You should contact your local authorities to find out what you should do with it next. Whatever you do, DO NOT dump the stuff down the drain, it will eat through your pipes just like any of the other etchants.

Alternatively, instead of disposing of the etchant, you can re-use it again and again. In fact, after etching a few boards with this solution, you will have successfully made Acid Cupric Chloride (see below). You can also find a detailed tutorial on etching at Muriatic Acid etching tutorial

[edit] Sodium Persulfate

More environmentally friendly than ferric chloride. Can monitor the etching as initially clear new etchant solution turns blue from the copper ions.

[edit] Acid Cupric Chloride

Dead simple etchant made from ordinary, store-bought chemicals (hydrochloric acid and hydrogen peroxide). Has the advantage that it can be regenerated by bubbling oxygen/air through it, or by adding more H2O2. In addition, it doesn't get used up: the etchant bath simply grows with use (kind of like sourdough starter…) 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 hardware stores or pool supply stores as Muriatic Acid)
  • 3% Hydrogen Peroxide, H2O2 (available from any drug store)
  • Plastic or Glass Pans, Jars, and tongs (no metal)

Directions:

  1. Mix your HCl and H2O2 1:1 in a non-metalic container, making sure to add the acid slowly to the H2O2. DO NOT ADD THE H2O2 TO THE ACID!!!
  2. 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.
  3. 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.
  4. When done etching, save used etchant in a non-metalic container and mark clearly its contents.
  5. If your etchant has become a dark, murky green color, add a little bit of H2O2 or bubble air/O2 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.

[edit] 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 accordance with local laws.

[edit] External Links

[edit] Internal Links

Personal tools
Namespaces

Variants
Actions
Navigation
Toolbox