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I am trying to do a PCB toner transfer, however sometimes the transfer is imperfect and the really small traces fail so I would like to start over and reuse the board again instead of etching it.

I initially just wiped the toner off with acetone. But it still left marks where the toner was - I highlighted two occurrences but others are in the image too, see image: enter image description here

I then soaked it in acetone instead and scrubbed. But the marks remain unchanged.

Is there a recommended chemical to remove it? I do not want to sand or etch it off because the application is in RF and the design is very sensitive to copper thickness.

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    \$\begingroup\$ Solvents really will get almost all of it. Something like a scotch brite pad would get the last - it turns out that the resulting matte surface actually takes toner better anyway. People who are serious about geometric aspects of RF boards are typically using exotic substrates and milling or using a laser. \$\endgroup\$ Dec 6, 2019 at 5:39
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    \$\begingroup\$ Just use a very fine grit wet/dry sandpaper. If a very light sanding effects your board that much, I would think the chances of being able to successfully DIY etch it would be minimal. What are the frequency's your dealing with? \$\endgroup\$
    – GB - AE7OO
    Dec 6, 2019 at 8:26
  • \$\begingroup\$ @GB-AE7OO, Yes my chances of successful etching are pretty low. 12-14Ghz range If I run the simulation with only changing the copper height from a 1oz copper to a 0.5oz copper the effect i'm trying to study goes away until I readjust the other dimensions to compensate. I originally tried getting it manufactured but the quotes came back in 6 figures. The Hong Kong places I tried do not have access to the board material but on FR4 cost like $22. :( \$\endgroup\$
    – axawire
    Dec 6, 2019 at 19:55
  • \$\begingroup\$ I would just use a very fine grit paper and do it wet... Just enough until your "echos" are gone. That is about all I can think of. The highest frequency project I ever did was a SIMPLE 10Ghz to 5.8Ghz converter. Everything else was S band or below. \$\endgroup\$
    – GB - AE7OO
    Dec 6, 2019 at 20:20

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I had problems getting the toner off the PCB as well for years. The trick is to let the PCB soak in the acetone for a few minutes - it's important that the PCB be fully submerged. After a few minutes, take a q-tip and wipe the toner off the board while it's still submerged (IMPORTANT!) - the toner particles become suspended in the acetone and don't become embedded in the fibers of the PCB. Then just rinse the PCB in water. I use a paper coffee filter to filter out the toner particles that are suspended in the acetone and save it for reuse. Works every time. I have a Brother printer which is notorious for having problems with the toner transfer method. I use HP Premium Presentation paper (very glossy) - which works great. After ironing the image onto the PCB, submerge the PCB in water with some dish soap - let it soak until the paper falls off by itself (about 45mins). The soap breaks down the paper fibers. Good luck!

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  • \$\begingroup\$ I actually tried soaked these for days, I ended up just getting replacement material instead. \$\endgroup\$
    – axawire
    Feb 24 at 17:00
  • \$\begingroup\$ Read the above again. You need to keep the PCB submerged in the acetone while wiping the toner off the traces. Follow the above directions, if you are able to, and the toner particles will be suspended in the acetone and not be embedded in the PCB. It works every time! \$\endgroup\$ Feb 25 at 21:32

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