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Etching circuit boards — Parallax Forums

Etching circuit boards

Pat AlonziPat Alonzi Posts: 27
edited 2007-05-10 23:12 in General Discussion
Hey everyone,

I am trying to etch my own circuit board. I purchased a copper clad board at R-Shack as well as a bottle of the solution. I drew out my schematic using a sharpie marker and went over it 3 or 4 times till it was very dark. I then submerged it in a plastic tub with the solution. I also have it encased in a water jacket full of boiling hot water.

How do i remove the last bits of copper that are still left on the board?

Thanks,
Pat

Comments

  • FranklinFranklin Posts: 4,747
    edited 2007-05-09 03:09
    Most people use a small piece of sponge and rubber gloves to LIGHTLY wash over the surface with the etchant.

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    - Stephen
  • allanlane5allanlane5 Posts: 3,815
    edited 2007-05-09 03:40
    A dremel moto-tool, perhaps. They're also good for drilling through-holes.
  • Salvatore LorenzenSalvatore Lorenzen Posts: 2
    edited 2007-05-09 04:44
    I had a student work on this to build a homebrew BS2 project board. I learned a lot trying to keep up with or ahead of this student. We used single sided copper clad boards and the same Radio Shack etchant you are talking about. We opted to buy transfer paper (available from http://www.elexp.com/pro_npb5.htm ).

    When we etched it at room temp it would take 20-30 minutes (not a lot of options to heat the etchant in my lab). Sometimes there would be some spots of copper we could not get to dissolve. The methods we used were some fine grit sandpaper, the corner of a scotchbright pad. You shouldn't need to remove ALL of the copper, just enough to isolate your traces. Some PCB design software allows you to place copper pours so you only etch what is needed to isolate traces, not remove everything but the traces.

    The software that we used with those Press-n-Peel transfer pages was Dip-Trace. The free version allows up to 125 pins, does schematic capture and PCB layout from schematic.

    Hope this is helpful, we worked with this and on this from Sept. 06 to Feb. 07 -- He did place 1st in state for the project after all that.

    Sal Lorenzen
    www.techedguy.com
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-05-09 05:05
    This thread is being moved from the BASIC Stamp Forum to the Sandbox Forum.

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    Chris Savage
    Parallax Tech Support
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2007-05-09 05:22
    In many cases, the spots that don't etch lie under some sort of contaminent on the copper. One thing that's very important is for the board to be clean before you apply the resist. Go over it first with a Scotch-Brite pad until it's bright. Then clean it again with a coffee filter (the cheapest lint-free wipe you'll ever find!) wetted with isopropyl alcohol (the 99% kind, not rubbing alcohol). Let it air dry. After that, don't touch the copper with your bare fingers! Doing so will deposit a film of body oil that acts as a resist in its own right.

    -Phil
  • ForrestForrest Posts: 1,341
    edited 2007-05-09 10:48
    Phil has the right solution. Copper oxidizes fairly quickly so all manufacturers apply a chemical coating to protect the copper surface. You must remove this invisible coating before you image the board or draw the circuits.
  • crgwbrcrgwbr Posts: 614
    edited 2007-05-10 18:18
    Pat Alonzi said...
    ...I purchased a copper clad board at R-Shack as well as a bottle of the solution...
    Just a suggestion for next time, imho don't buy Radio Shack's boards. I have heard of numerous times when the glue between the fiberglass and copper dissolved. Hopefully it won't happen to your boards.

    Regards,
    Craig

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    I would love to change the world, but they won't give me the source code

    People say that if you play Microsoft CD's backwards, you hear satanic things, but that's nothing, because if you play them forwards, they install Windows.

    I spent a minute looking at my own code by accident. I was thinking "What the heck is this guy doing?"
  • ForrestForrest Posts: 1,341
    edited 2007-05-10 23:12
    crgwbr said...
    Pat Alonzi said...
    ...I purchased a copper clad board at R-Shack as well as a bottle of the solution...
    Just a suggestion for next time, imho don't buy Radio Shack's boards. I have heard of numerous times when the glue between the fiberglass and copper dissolved. Hopefully it won't happen to your boards.

    Regards,
    Craig

    I've haven't experienced this problem on any of the 5 boards I built from Radio Shack copper clad. There's an industry standard specification for the copper peel strength. So unless Radio Shack is selling rejected material - this shouldn't happen.
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