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Drilling PCBs

Discussion in 'Electronics & Electrics' started by GooSE, Sep 3, 2006.

  1. OP
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    GooSE

    GooSE New Member

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    I have looked into ammonium persulphate, but it seems like you need to heat it and agitate it to get etch times that even start to resemble those of ferric chloride. Ferric chloride just seems more attractive due to it having decent etch times at room temperature with minimal agitation. Am I correct in saying this?

    EDIT: I have read about a hydrogen peroxide + hydrochloric acid solution that is supposed to be a middle ground between ferric chloride and ammonium persulphate in regards to time, and also provides a clear etching solution. Thing is, I haven't been able to find any specifics about mixture ratios and how strong the acid should be... Does anyone know anything about this?
     
    Last edited: Sep 10, 2006
  2. Goth

    Goth Grumpy Member

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    Yeah, this is actually what i use all the time for etching.

    I personally use 2:1:1 HCl, Hydrogen Peroxide and Water respectively, where the HCl is about 33%, which is typical for the concentrated commercial grade stuff, and the Hydrogen Peroxide is 50%.

    If you use 6% Hydrogen Peroxide, which is the antiseptic stuff you'll get at a chemist, i would start with something like 1:1 mixture, which should work OK. Hydrochloric Acid is commonly available from hardware or pool stores, though i don't like to use the Diggers brand, as it contains an Iron salt which will turn brown, much like Ferric Chloride, when you mix it.

    This stuff is cheaper than the usual etchants, and is usually a clear solution, just like Ammonium Persulfate, but doesn't need to be heated.
     
  3. OP
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    GooSE

    GooSE New Member

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    Cheers for the tips Goth. I might look into trying that.
     
  4. Goth

    Goth Grumpy Member

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    A more concentrated solution equals a faster etch, if you're using dilute peroxide it will probably be a fairly slow etch, but if you're using more concentrated chemicals you need to dilute it appropriately with water or your reaction will be violent. It will work just fine at room temperature. Generally i test the solution using small offcuts of PCB stock. You don't need a lot of agitation, i generally just use an ice cream container or plastic tray and rock it back and forth occasionally.
     
  5. OCMunkee

    OCMunkee Member

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    Hey Goth (sorry, slightly off topic) a couple of Qs:
    -How do you print your PCBs?

    -What tools do you use when doing the etching? Like tongs and things, I'm guessing if you're using Hydrogen Peroxide and HCl then you'll need plastic tools of some description?
     
  6. OP
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    GooSE

    GooSE New Member

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    I'm certainly no Goth, but the best method seems to be using glossy photo paper in a laser printer and then using an iron to transfer the toner onto a PCB.
     
  7. nux

    nux Member

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    Thats what I use. And I bought a plastic tuppaware type container with a lid to etch in, and plastic tongs to move it around and stuff.
     
  8. Goth

    Goth Grumpy Member

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    +1 to glossy photo paper and a laser printer.

    Photography tongs are handy if you've got them, otherwise just use metal forceps, long nosed pliers, tongs etc. They'll corrode a bit, but if you have a dodgy pair that you dedicate for this task, it's no big deal. Or wear a glove and simply pick up the board.

    Any old shallow plastic or glass vessel (i.e. Tupperware or icecream container) is fine.
     
  9. Thraxeh

    Thraxeh Member

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    this is interesting, i think i might give this ago. The only thing stopping me last time was a drill press...
     
  10. genesis[OFT]

    genesis[OFT] (Banned or Deleted)

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    Why use drills to make PCBs when your school has a 20 grand Roland CNC Milling Machine to do it all for you? :p

    Hope all goes well though....steady steady hand... :wired:
     
  11. Thraxeh

    Thraxeh Member

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    where can i find come Ferric Chloride ?
     
  12. Goth

    Goth Grumpy Member

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    Etchant - Ammonium Persulfate or Ferric Chloride etc. - can be had from your local usual retail electronics suppliers.

    That's just not going to work... unless you specifically design your PCB with the IC flipped over to the other side.


    http://forums.overclockers.com.au/showthread.php?p=7006263
     
    Last edited: Mar 3, 2007
  13. Thraxeh

    Thraxeh Member

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  14. Goth

    Goth Grumpy Member

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    It doesn't make any difference, really.

    Ferric Chloride is a liquid which can be used as is, ready to go, and doesn't need heating.

    Ammonium Persulfate crystals need to be dissolved in hot water, but are a lot less messy and won't stain.

    OK, just had a look at the site.

    Personally, for etching Aluminium, I would use moderately dilute Hydrochloric acid or a moderately dilute Caustic Soda solution to etch - Copper etchants really aren't designed for Aluminium, and could be a little unpredictable.

    But it does seem that Ferric Chloride works, anyhow.

    Caustic Soda can produce a kind of anodisation-like matte white surface on etched Aluminium, if you're interested in that.

    Anyhow, DSE sells Ferric Chloride solution just like they've used there.
     
    Last edited: Mar 3, 2007
  15. Thraxeh

    Thraxeh Member

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    Ahh i see, thanks for the reply!
     
  16. OP
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    GooSE

    GooSE New Member

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    You could try the acid + peroxide solution which I described in my thread (the link that Goth posted above). It's fast and cheap.
     
  17. Goth

    Goth Grumpy Member

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    But I really don't know what an Ammonium Persulfate solution would do to Aluminium - If you were going to try it, i'd try a cold solution first. Maybe dilute it.

    Since you're etching Aluminium, the entire knowledge base that surrounds etching Copper on PCBs doesn't necessarily apply - Aluminium is a lot more reactive than copper.

    No, don't try that with Aluminium. Diluted HCl by itself would do the trick, though.
     
  18. Thraxeh

    Thraxeh Member

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    I will stick with the Ferric Chloride, if i can only source the Ammonium Persulfate then i will try your suggestions.

    Thanks again
     
  19. OP
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    GooSE

    GooSE New Member

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    Whoops, I didn't read Thraxeh's link... I thought he wanted to etch some copper PCBs, seeing as that's what this thread is about. :weirdo:
     
  20. Thraxeh

    Thraxeh Member

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    i'm doing that as well :p

    i dont have any money though, so my little project will have to wait :(

    trying to find some of that PNP stuff, jaycar have it, but they have 5 sheets of it, for $30, i dont need 5 sheets.
     

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