pcb etching

Discussion in 'The Projects Forum' started by tonymac, May 12, 2013.

  1. tonymac

    Thread Starter New Member

    Jan 20, 2012
    Can any 1 help me with how to etch a pcb.I have followed the toner transfer process to the letter and all is well upto submersing the copper board{with 1 sided glossy paper with board layout}into the heated ferric chloride.The process seems to be too slow when i do it and some of the tracks are dissolved before the copper clad to be dissolved.Any help appreciated,regards tony.
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    It takes trial and error.

    Common errors:
    - no board prep - make sure to scuff or otherwise polish oxides from the copper board. Even a board freshly out of a shipping bag will need some type of freshening up. People recommend ScotchBrite, Steel Wool, pencil eraser, ...

    - Iron too hot (starts blistering PCB plastic) or oxidizing copper (color change)
    - Paper removed too quickly (pulls traces off of copper). Soak plenty long to insure the paper comes off without pulling copper off. Try adding some DAWN or other liquid dish soap to help soften the paper.
    - I find immediate wetting of the hot PCB w/ paper fused to it helps. Otherwise, some shear force is on the toner as the paper cools and has different thermal expansion (shrinking) than the PCB copper. The paper immediately loses strength as it is wetted and shear is removed.
    - Make sure you heat evenly and long enough (without overheating board). Move the iron around and use some sponge/fabric/paper towel under the PCB to distribute pressure. Also use paper towel between pattern and iron to distribute weight/pressure. Move the iron around. Lift the paper towel and move it around to insure the little air pillows in the paper towel is not always in the same spot.
    - When removing paper from PCB. Allow it to sit plenty long and rub gently only with your fingers. Don't damage the toner. It is very thin plastic and rolls up easily - away from the copper.

    - When etching, try to float the PCB on the surface of the Etchant (face down). It is fairly easy on 1 oz copper or less (2 oz copper is too dense). The surface tension of the etchant will keep the board up and allow copper solids to drop to bottom of container instead of build up on the board. If your board sinks, remove it, rinse it and dap it dry with a paper towel and try again.

    Finally, make sure your traces are more than 0.01 inch (hopefully more than 0.015"). It is difficult to consistently get fine traces. Also, it is actually difficult to get big flood areas to etch without pits.

    Exact toner type and iron temp, time, pressure take a while to dial in for your needs. Remember that a larger board takes more time to heat up than a smaller board.
  3. Wendy


    Mar 24, 2008
  4. whatsthatsmell

    Active Member

    Oct 9, 2009
    Wait - are you submersing the board into the ferric chloride with the paper still attached? - Or am I reading this wrong?

    Soak the paper off first with plain water. (See above posts)