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PC Board etchant, reuse, how many sq. in. before spent? — Parallax Forums

PC Board etchant, reuse, how many sq. in. before spent?

xanatosxanatos Posts: 1,120
edited 2009-07-13 13:29 in General Discussion
Quick question for those of you who use Ferric Chloride etchant - how many square inches would you say you get to a given volume of etchant before the etch time is significantly increased, ie., the batch is spent?· Assuming standard 1 oz copper clad boards.

Also - anyone doing anything to successfully reclaim/reuse/revitalize the etch?· I try to be as environmentally friendly as can be everywhere else, but I really feel like I'm missing the mark on this particular item!

Thanks,

Dave

·

Comments

  • LeonLeon Posts: 7,620
    edited 2009-07-09 21:21
    I just use it until it takes about 2x as long as fresh solution.

    You can extend the life with hydrogen peroxide and hydrochloric acid. The copper dissolved in it will become cupric chloride, which is a good etchant.

    Leon

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  • chaosgkchaosgk Posts: 322
    edited 2009-07-09 21:51
    I simply use Hydrogen peroxide and HCL with some distilled water added in for good measure not even worrying about using the ferric chloride.· Seems to work fine.· $.99/quart peroxide and $5/gallon for 30% HCL.·
  • $WMc%$WMc% Posts: 1,884
    edited 2009-07-09 23:37
    Thanks for the info on H2O2 and HCL acid

    Ferric chloride solution is a pain to use,Beside being expensive. It needs to be warmed up and stains every thing it gets on.

    __ManyThanks________$WMc%______

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  • william chanwilliam chan Posts: 1,326
    edited 2009-07-10 03:54
    I think using "copper pour" in your design can reduce the amount of etchant needed.
    I just can't figure out how to use copper pour in Eagle. !

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  • PainlessPainless Posts: 69
    edited 2009-07-10 22:41
    Found this recently, how to make your own re-usable etchant. Haven't tried it myself, but might when my current bottle runs out.

    www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-11 20:29
    Couper pour will both extend the etchent life and make etching easier.

    The icon for coper pour is the polygon tool. After putting down rename to vss or whatever net you want to use.

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  • xanatosxanatos Posts: 1,120
    edited 2009-07-11 22:04
    Hi everybody... and THANKS for the info. The instructables link was awesome... especially since I see I can use my already-available used sodium hydroxide to precipitate the copper out of the FeCl and neutralize it - that's a double bonus!

    Good stuff folks - thanks very much!

    Dave
  • pwillardpwillard Posts: 321
    edited 2009-07-12 02:51
    The instructables example is the same as the mentioned "info on H2O2 and HCL acid"

    I learned this from GOOTEE years ago and love it. It's the only way to etch for me now. I really like seeing what I'm doing, BUT!!!! do it outdoors and have some form of mask over your nose and mouth. Your lungs do NOT like breathing HCL.

    I buy LONG woodstick cotton swabs... the kind used for electronic equipment cleaning... not ears and disposable rubber gloves. The cotton swabs are used to agitate the mixture close to the copper regularly during the etching process. No need for heat or bubbles like with ferric chloride.


    If you spill it... (god forbid)... it leaves no stains (unlike permanent staining FECL) but it WILL dissolve concrete so flush with lots of water.

    www.fullnet.com/~tomg/gooteepc.htm

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  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-12 10:33
    HCl/H2O2 all the way. I use 2 parts H2O2 per 1 part HCl. Etching generally takes ~30 minutes. Oh, and as for your OP, when you're talking about $2/gallon of etchant... who cares how long it lasts? [noparse];)[/noparse]
  • LeonLeon Posts: 7,620
    edited 2009-07-12 10:38
    I use FeCl3 with the etchant in a plastic food container in an old washing-up bowl with about 1" of very hot water in it. I rock the etchant container continuously - etching takes about 5-10 minutes.

    Leon

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  • pwillardpwillard Posts: 321
    edited 2009-07-12 15:54
    Phil? ~30 Minutes?

    Mine are done in 5... maybe 10 tops.

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    There's nothing like a new idea and a warm soldering iron.
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-12 20:47
    Well, 30 minutes is without rocking or anything. I usually get a bite to eat while it's etching, then come back when it's done to drill the holes. pwillard, you're right - 5 or 10 minutes is about what it takes if you're continuously sloshing it.
  • LeonLeon Posts: 7,620
    edited 2009-07-13 13:29
    The ARRL Handbook used to have a description of a motor-driven agitation system. A heat lamp was placed above the container and it was rocked by an eccentric cam fitted to a small motor.

    Leon

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