Ferric Chloride and PCB

Discussion in 'General Electronics Chat' started by Ubergoober, Aug 5, 2008.

  1. Ubergoober

    Thread Starter New Member

    Aug 5, 2008
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    I just have a question about making PCBs. I live in china and am presently studying electronics. I read a couple of tutorials about making PCBs and have gathered all the things to make it. However the Ferric Chloride is not liquid but a bunch of blocks. My question is 1. Is it safe to mix the chemicals at home 2. Besides Ferric Chloride what do I add to make the etching solution and what is the ratio of the ingredients. Thank you so much for helping me:)
     
  2. theamber

    Senior Member

    Jun 13, 2008
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    Yes, anything you do is safe as long as you take the necessary precautions. The thing with Ferric Chloride is that it has to be hot in order to produce faster and better etching. Fast etching will produce better quality edge and more consistent lines.
    Warm the solution or the water in the microwave just warm to the touch but not too hot or it will start to release a lot of fumes. Use a fan to ventilate the area or better do it outside. Wash everything real good after finishing.
    I will say mix 250g crystals in small doses slowly to 500g warm water. You will need to try with a spare board because the fist time you may mess up. Trial and error until you learn.
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    I have to agree to a point. in a premixed solution I've never heated it. I mildly hand agitate it to get good results. The heat speeds up the reaction a lot though, which makes it easier overall.

    The fumes are no joke. I buy mine from Radio Shack premixed, and a bottle set next to anything metal will eat the metal like acid. I ruined some nice tools that way. My solution to the problem was to take a paper towel and "seal" the seam between the cap and the bottle, then taping it in place with masking tape. Works like a charm, but the paper towel and tape comes up extremely brittle when I had to open it up again.

    I've worked on a commercial etcher at my old job, where they heated it and power sprayed it on the board in question. My understanding was this kind of setup allowed for really fine etches, but even though I serviced it I never saw it work.

    Disposal is a serious issue too, this stuff will eat pipes. I seal it in tupperware with lots of metal hardware, let it deactivate, and then pour it out. It isn't toxic, but you do have to treat it with caution.
     
  4. Ubergoober

    Thread Starter New Member

    Aug 5, 2008
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    Thank you Dear theamber and Bill Marsden for your advice. I won't be able to try it out for a few weeks because I don't have any safety goggles. As most of us foreigners, our nose is much bigger then the Chinese people so I will have to wait to a friend which is coming from the states to bring them ( it should be a in three weeks). In the meantime I will try to not have this chemical dissolve me or anything or anyonelse for that matter and fiddle with my solderless bread board. When I get the goggles I'll try and post my results. Thanks so much for all the help
     
  5. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    A safe way to warm ferric chloride is to place the container into another container of hot water. As far as concentration goes, better strong than weak, in my experience, and wear old clothes because that stuff stains everything it touches.
     
  6. arthur92710

    Active Member

    Jun 25, 2007
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  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    FeCl has one very great advantage - it has an extremely long storage time. I can get 10 years usage out of my 4 gallon supply. I've used ammonium persulfate with good etching, but poor storage time.
     
  8. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,699
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    I have had problems with easily oxidizable resists (e.g., photoresists) with etchants prepared with HCl and hydrogen peroxide. I have not tried the persulfate etchants.

    Ferric chloride works well, and frankly, I don't see the justification to stop using it. It is simply one alternative to use. In my case, I use a magnetic stirring hotplate, Teflon stir bar, regulated temp at 60 to 65°C and get fast, reproducible etching. One big advantage of that system is that there are no bubbles and no splatter.
    John
     
  9. Ubergoober

    Thread Starter New Member

    Aug 5, 2008
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    Say what do I use to drill the holes in the circuit board. Thanks you all
     
  10. Wendy

    Moderator

    Mar 24, 2008
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    Dremel sells adapters to turn their basic units into drill presses. Works for me.
     
  11. kammenos

    Active Member

    Aug 3, 2008
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    Hallo

    FeCl is quite a safe but messy liquid. It means that will not burn your hand if falls on it, but it will make a hell of a mess on your clothes. It creates a dark yellow dirt that cannot easily removed.

    The solution percentage is shown on the packet of fecl. it is usually sold in packets that need 1lt of wtare to mix. You can use half a packet with 0.5 lt etc etc etc.

    You will get more info here http://www.pcbheaven.com/workbench/pcbmaking/

    Remember, keep the water hot, NOT boiling!!!
    DO NOT BREATHE THE SMOKE OUT OF IT
    keep it in a well ventilated or open air space

    For better results, you may need to have some agitation

    Good results :D
     
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