Toner transfer explained step-by-step

[Tanjent] send us a link to his tutorial on the toner transfer process for fabricating circuit boards. We’ve seen a lot of these in the past, but we liked how his is straight to the point while also sharing several tips and options along the way. Notably, he ”tints” the copper clad before trying to adhere the toner to it by swabbing on a bit of etchant. His reasoning for this is that the toner has more trouble sticking to the shiny copper. Just a bit of etchant will pit the surface and let the toner stick better.

He’s still using paper as a medium and not printing toner powder directly to the copper clad. His paper of choice is HP Brochure Paper while we use glossy pages from the union newspaper. But like us, he does use copper chloride as an etchant, which you can learn to make yourself. We’re still looking for a definitive solution for disposing of this chemical. We’ve been using the same batch for years and recently it’s turned cloudy with impurities. If you’ve got disposal tips let’s hear them in the comments section.

Comments

  1. Brennan says:

    I said it before and I’ll say it again – With a little bit of prep, the UV light exposure method is more accurate and can be done in about the same amount of time if not a few minutes more. The only downside is the cost of the presensitized boards and developer, but it’s more than worth it if you do a lot of surface mount work.

  2. skitchin says:

    I’d really like to see more focus on disposal of these left-over chemicals. The amount of info I am able to find is pathetic.

  3. Brian Aday says:

    Had the same problem with the copper and toner, I used Scotchbrite to scuff the surface and it worked. I like his use of etchant better.

  4. Miroslav says:

    A quick google search returned several good links describing fairly simple disposal method.

    Here is the first one listed

    http://www.mgchemicals.com/techsupport/ferric_faq.html

    “he solution must not be put down the drain because of residual copper ions left in it. To make it safe for disposal, you can add sodium carbonate (washing soda) or sodium hydroxide to it to neutralize it, until the pH value goes up to between 7.0 and 8.0, testing it with indicator paper. Copper will be deposited as a sludge. Allow the sludge to settle, pour off the liquid, further dilute it with water and then it can be poured down the drain. Collect the sludge in plastic bags and dispose of it as required by your local waste authority.”

  5. Joel says:

    I bet you could neutralize the stuff with a weak base. Don’t take my word for it, and definitely look into safety issues, but baking soda would react with cupric chloride to give a solution of table salt and a copper carbonate precipitate, the latter useful to artists who work in media like ceramics, pyrotechnics, or self-made paint.

  6. Pyroplasma says:

    I don’t know exactly what is in the etchant, but from my understanding, the nasties are the HCl, and the copper ions. Please correct me if I’m talking out of my ass btw. Would it be possible to add baking soda to neutralize the acid, then evaporate the liquid to leave copper salts and various other less toxic salts? This could then be disposed with a load of copper at your local recycling plant, they might even accept it straight as dirty copper.

  7. CF says:

    Try this. Lets you visually see if you can just pour it down the drain.

    http://homepage.mac.com/bharlan/iblog/C1232924160/E770484800/index.html

  8. Brad says:

    CF, I saw that one too, but did you see that it would require 20,000 gallons of water to dilute 1 gallon of copper chloride… Seems like baking soda would be cheaper.

  9. Miroslav says:

    @CF, Brad
    Swiming pool of water will ONLY make it LEGAL to dispose it, not safe – you will still release the same amount of copper to the water systems, just will take more time to do it :)

  10. Eviro says:

    Add aluminum foil until green color disappears to precipitate copper metal and form aluminum ions in their place (MUCH less enviromentally harmful)

    Decant solution from the copper powder/sludge which has formed. Wash the sludge with water a bit to remove traces of acidity. You can just throw this sludge in the trash can once it is washed.

    Then neutralize the solution which remains with baking soda/lye to form aluminum oxide/hydroxide sludge and pour it down the drain.

  11. Eviro says:

    Also,
    CF, Let’s not even START getting into how the widespread policy of diluting nasty and harmful materials until it’s ‘legal’ to dispose of them is a disgusting and unethical practice.

  12. Pete says:

    I have never had any trouble with photoetching PCB’s. I guess you should stick with whatever method you are comfortable with though. MG Chemicals sells a kit with nearly everything you need to photoetch PCB’s

    http://www.mgchemicals.com/products/416k.html?PHPSESSID=20eb97b62820fc01406a1fad3902c53f

    you will also need a light source

    http://www.mgchemicals.com/products/416x.html

    and some transparencys for whatever type of printer you have. If you ask the people at the office supply store they will open a pack and sell you just a few sheets so you dont have to buy a $50 pack of transparency sheets.

  13. Mark Richards says:
  14. nipples says:

    copper sulpate is used still as spray for potato blight so if u etched your board with sulphuric acid it should be safe to add to the farmer’s bulk tank.

  15. Frogz says:

    [flamebait] just do like i do, dilute 1 liter of cucl to 1 gallon of water so it doesnt eat your drainage system[/flamebait]

    but as i was going to say, onion skin paper(most/all office supply stores carry it) should work great for this purpose

    http://www.google.com/products?q=onionskin+paper

    hm… once i get ink for my printer i got a tutorial that i bet will get OVER 50,000 million hits

  16. DXR says:

    I have a friend, in uni, that is thinking of disposing of the etching liquid with Calcium oxide, it is alkaline and may neutralize the etchant that is acid, at the same time it will turn it into a solid mass… maybe…

  17. xorpunk says:

    A company I once worked for used something basically the same as Enviro mentioned with aluminum foil. Except both bi-products were sold to a biochem company to be used is some form of manufacturing.

    To be honest I think it’s ridiculous people are using such a crude method just to etch PCB still..

  18. pablo says:

    If you’re just worried about impurities clouding your etchant and would like to keep using it, have you considered running it through filter paper? Keeps the ions, filters out the sludge and particulates. Not entirely a win/win, but it can keep you reusing it longer.

  19. Phil Burgess says:

    Check if your municipal waste service offers hazardous materials disposal. Due to landfills approaching capacity, metropolitan areas are getting more aggressive about diverting waste and recycling. For example, where I currently live, residents can make two free hazmat drop-offs per year at the local facility (e-waste, too). Just be sure to label things as clearly as possible, e.g. “Used circuit board etchant: ferric chloride w/copper ions” (or “copper chloride” if that’s what you’re using), perhaps a corrosive warning or anything else that might be instructive.

  20. Anonymouse says:

    Used PCB etchant is not nearly as harmful as some believe. Neutralize with baking soda, filter the precipitate, pour the liquid down the toilet, and throw the filter cake in the trash. Consider how much copper you actually etch off a PCB. Now find a picture of the statue of liberty. That is a copper statue. That is what you just put in your garbage can.

  21. WestfW says:

    I think in many areas of the country, people still dump copper sulfate down their drains in “couple of pounds per year” quantities to keep tree roots from invading the pipes. Which makes the amount of copper you’d be dumping from a typical hobby PCB shop pretty insignificant… (copper chloride, copper sulfate, doesn’t make much difference from a pollution point of view…)
    Copper sulfate is also a common agricultural chemical; sprayed all over various plants as a fungicide…

  22. Devcoder says:

    Does anyone know how exactly this works? HCL doesn’t dissolve copper as far as I know and I’m not sure how adding H2O2 would help. Chemical equation anyone?

  23. Walky says:

    If you make pcbs on a usual basis, build/buy a small CNC with a low-runout router, 10º engraving bits and 0.8mm endmills (the latter for drilling and profiling). I tell you, after making a pcb with one you will never, ever use that nasty stuff again. I used to take more than an hour to make a couple of pcbs, now it takes me 5 minutes and the result is perfect (even with SMD). Besides, you can cut the board with any shape you need.

  24. Anonymouse says:

    H2O2 oxidizes copper, and HCl does dissolve copper oxide. After a while, the H2O2 has all decomposed, but then you have CuCl2 floating around and

    CuCl2 + Cu –> 2CuCl

    The chloride ions can be replenished from the HCl, and dissolved oxygen.

    4CuCl + 4HCl + O2 –> 4CuCl2 + 2H2O

    This is why the must be periodically refreshed by adding more H2O2, or by bubbling air through it (preferably outside and WELL AWAY FROM ANYTHING MADE OF STEEL). This reaction also consumes the HCl, so it must also be topped up (but less often).

    Of course, the actual mechanics of all this are happening with ions dissociated in solution (except for the metallic copper), so the above is somewhat simplified.

    Running on the assumption that the etchant looses potency because the solvated copper concentration reaches equilibrium, plating out the copper as Enviro suggests might restore some potency, but you couldn’t use aluminum. Perhaps you could electroplate it out with a carbon anode, but I doubt that the pittance of copper you would extract would be worth the immense hassle of an electrochemical cell. Not to mention, it would probably also belch Cl2.

    Probably best just to flush it down the sewer with a sodium carbonate chaser.

  25. !!Dean says:

    I second what Phil Burgess said… to check with your local municipality. For example, here’s what Houston offers: http://www.houstontx.gov/solidwaste/hhw.html

  26. fco_bcn says:

    About the choice of paper, fashion magazines work really great. My favorite is Vogue.
    As a bonus, you can watch fine ladies while doing your stuff.
    Also, before ironing the pcb, use sandpaper, after that, clean with acetone. Avoid touching the copper.

  27. Tachikoma says:

    I actually use sticker backing paper as the printing medium. It’s the glossy stuff you peel from stickers, which you usually end up discarding. I have lots of those lying around from work (big sheets) so I decided to give them a shot one day.

    The idea is to print on the glossy side, do the heat transfer method of your choice, then simply peel the backing paper away from the fused toner. The latter part is what makes this paper awesome, you effortlessly remove the paper as if you were peeling a sticker.

    The biggest hurdle is actually getting the toner to stick on the paper sufficiently long enough. The glossy side is so smooth that the toner starts to flake off from trivial movements and flexing. Sometimes the printer itself rubs off the toner as it spits out the paper.

    You need to use fine abrasive sponge to roughen up the glossy surface, just rough enough for the toner to stick. Can be a hit and miss at times; obviously you need to use trial and error to find the ideal roughness. The end result should look somewhat matte, as opposed to very glossy. Even in this state the toner is VERY sensitive to mechanical stress, so you need to handle with care and definitely not touch the toner – once you do it’s all over. The beauty is that you can reuse the paper if you screw up – just use cotton wool to wipe of the toner and start again.

    The second tricky bit is placing the blank PCB on the print in such way that it does not shift the or perturb the toner underneath. That means no sliding, twisting, rotating, shearing. Must fall flat. Once it’s down it stays down. Use a tape that is sticky enough to keep the glossy paper fixed to the PCB. I use a hot clothing iron as a heat source. I just put it on top of the PCB and let it sit under its own weight for a while. NO movement.

    Once done, peel the paper off and you have a fairly decent transfer. This seems to work well for non-SMD work, about 0.7 to 1mm wide tracks. Anything smaller is not recommended.

  28. binarzero says:

    I’ve used this stuff but in 6″x 4″ form for toner transfer and it works very well.

    http://www.techstore.co.uk/browse.php?a=p&prodLineID=107051

  29. AO says:

    I recently gave the toner transfer method a go for a first batch of home-etched PCBs. I found glossy magazine paper worked great, and peeled off the boards really easily after about a minute of soaking.

    I recently posted a detailed article on my blog about my experience w/ the process:

    http://technoetc.net/blog/2010/05/14/printed-circuit-board-pcb-etching/

    I haven’t tried the photo option yet, and I’d love to try the CNC method mentioned above!

  30. azharee says:

    not ready please help me

  31. Johnny The Swft says:

    I have been using Tachikomas method (using sticker sheets and I find the best method is to heat the metal you are going to stick the toner to. Do not heat the paper with the toner.

    When you lay the sheet toner down on the hot metal the toner sticks to the metal and peels off the paper.

    I have done this and got 100% toner transfer.

    not 99.9% …100%

    You cant see anything left on the printer sheet AND you can reuse it!

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