Chemotransfer for DIY PCBs

Making PCBs with the toner transfer method has been around since you could buy your traces at Radio Shack. There are a million techniques for removing copper from sheets of fiberglass, from milling to using resist pens, to the ubiquitous laser printer toner transfer. Here’s a technique we haven’t seen before. [Darko Volk] is calling this ‘chemotransfer’. It’s mostly a laser printer toner transfer process, but the toner is transferred from paper to copper with the help of a special mix of solvents.

This chemotransfer process is almost identical to the usual process of making a toner transfer PCB. First, the design is printed in reverse on dextrin-coated paper, the paper is placed down on polished copper, the entire assembly is sent through a laminator, and finally the board is etched with the chemical of your choice. The key difference here is a solvent applied to the copper just before the design is laid down. [Darko Volk] made a mixture of 25% “cleaning petrol” (benzene, naphtha, or gasoline, or some sort of light hydrocarbon, apparently), 5% linseed oil, and 70% isopropanol. This apparently aids in releasing the toner from the paper and sticking it down to the copper.

From there, the process is effectively a standard toner transfer process. [Darko Volk] is using a solution of sodium persulphate for the etch, and rigged a camera up to a CNC machine for the drilling.

This process can be expanded to two-layer boards very easily using a light table to align the layers of paper before placing them down on the copper. You can check out a video of the fabrication of a single side and double sided board below.

Thanks [Andrej] for the tip.

55 thoughts on “Chemotransfer for DIY PCBs

    1. Looks like it and thanks for that link which I apparently missed it when it was originally posted. I have no issues with my toner transfer process, but am limited to thinner PCB material because of the need to pass it through the laminator. The cold transfer method will allow thicker PCB material to be used. Hurrah!

      BTW, in the Hackaday article it simply says “alcohol” which led me to wonder what TYPE of alcohol to use. In the linked Instructables it says ethanol (grain alcohol – booze), but the guy apparently bought what I suspect is pure stuff from a drug store instead of using the vastly easier to obtain denatured alcohol which is typically 90- 95% ethanol with stuff in it to make it undrinkable (because the government wants to tax the drinkable version).

      ANYWAY, it appears that the essential part of getting that process to work best is to read ALL of the comments below the associated Instructable guide.

        1. I only skipped through the above video once I went to the Instructables link for the simpler method with fewer and better defined solvent components and with especially useful user comments describing actual experiences using it. In the method described in the column above, “cleaning petrol’ (benzene, naphtha, or gasoline, or some sort of light hydrocarbon, apparently)” is an inadequately defined ingredient IMO.

  1. The acetone and isopropyl alcohol works just as good and doesn’t need heating from a laminator but the pressure of the rollers would help.

    I use Toner Transfer from a color laser printer to transfer decals to instrument faces. The best thing about using acetone and isopropyl alcohol is that you can transfer to surfaces that wouldn’t handle the heat of a laminator.

      1. Did you paint the surface white first.

        Color laser uses CYMK (cyan yellow magenta black) which are the subtractive primary colors that need to placed on a white background unlike the additive primary colors red green blue that are placed on a black background.

    1. Given the toner is disolved by the chemicals, how much does the image bleed from being squished by high pressure? When trying the iron toner transfer method, if I press too hard the image becomes *very* blurry and doesn’t etch well.

      1. My laminator is very tight. Sometimes I have a hard time getting boards to fit through without tearing up the transfer paper. Sometimes it takes a couple of tries. When I do manage to get it through though I do not notice any blurriness from squeezing. I only see that if it is not tight enough and the paper is allowed to slide a little.

        1. It could be the same product they sell (under commercial names and at inflated prices of course) to remove stickers safely, the correct name should be “adjusted gasoline” though I’m not sure if it’s the same product.

      1. Yeah I’m wondering if white gas or coleman fuel isn’t the closest thing here.

        Motor fuel gasolines, among other problems have metal deactivators in, so it is likely to passivate the surface of the PCB and not let some etchtants work…. though I’m fairly sure ferric chloride would burn through it.

    1. I use 8 parts Isopropyl alcohol to with 3 parts actone – much more human friendly than benzine if benzine is a hydrocarbon?

      Acetone is a ketone which isn’t the best for humans either but it’s probably better than a hydrocarbon and when mixed with a higher volume of Isopropyl alcohol it’s impact is reduced further.

      The closest thing to benzine that I have used is “throttle body cleaner” for cleaning car intake throttle bodies and I avoid that as much as possible but if I can’t avoid using it then I use a mask with organic filters and of course protective clothing and eye protection. Though I do use a MAP replacement flame which may possibly have some benzine in it but I assume it to be safe as a product retails for that specific purpose.

      Also I noticed in the video that you have to scrub the paper away from the toner. The article says you are using dextrin coated paper. I use pulsar (brand) dextrin sheets and drop them in water and they just peal off the PCB completely by themselves in 5 to 10 minutes. I just gently rub water over the PCB to remove any still undissolved dextrin.

          1. Thank for that. I will go look.

            There also seems to be some confusion here between benzine and benzene unless there actually the same and I am the one that is confused.

      1. Yes, benzine is a known human carcinogen. It’s the primary contaminant from the “Love Canal” incident! If they don’t sell it for cleaning purposes in your part of the world… there is probably a good reason for that.

  2. I just put Elmer’s glue stick on the paper before printing. After ironing the paper to the board, soak it in water to dissolve the glue and the paper just floats off leaving the traces on the board.

  3. Great share and beautiful walkthrough of the process.
    Thank you for sharing!

    I loved seeing that you used a Wolven wheel to clean the board (I would love to have one!😀). But a serious question is “do you dress the wheel with anything or just use it dry?

  4. VM&P naphtha, petroleum ether, ligroin, white gas, Coleman fuel, or Shellite as we would call it in Australia. A vaguely defined non polar, water insoluble mixture of mainly C5-C8 aliphatics with no residue on evaporation and no additives.

  5. The music is annoying and the video is best watched with audio muted – there is no valuable audio.

    The neat solder tinning is nice to watch, and the camera system that manually spots all the holes, generates G-code and drills them is impressively nice. The use of a proper guillotine for chopping the board neatly, without hacksawing, is also nice.

  6. Interesting. At first I thought why add even more messy chemicals to this already caustic process. He even uses a laminator and a laminator would transfer the toner all by itself. It seems very unecessary. But.. he did achieve a very clean transfer. I’m not sure a laminator by itself could do so good a job so hey… good work!

    But… something important seems to be missing. Don’t try this one at home kiddies without this one more ingredient… http://alturl.com/2s6y7

  7. Hey,

    as a chemist I might give you guys a little insight into the health hazards of the solvents which are used in this process.
    All are flammable, keep them away from hot surfaces e.g. reflow / soldering stations. The person in the video uses quite a lot of solvent mixture, work in well ventilated areas. Do not inhale the fumes :)

    Aceton: Degreases the skin, is often used in nail-polish remover. Breaks through typicall Nitrile / Latex gloves. Overall: not the most unhealthy / dangerous chemical. Girls use it ‘all the time’ :)

    Isopropanol: flammable, properly the most non-threatening chemical here

    Cleaning petrol: The stuff you can buy OTC is mainly a mixture from lower, branched alkanes. The branches ones are not as unhealthy as the linear ones, especially n-Hexane. These compounds should not be mistaken with the petrol / gas you guys use in your car. Mixtures of these alkanes are uses as lighter fluid for Zippo lighters and as acetone the mixture will degrease your skin upon contact. Overall: Can easily be handled by anyone with the usual precautions.

    Regarding the “degreasing” of your skin: Simply to not pour the solvent mixture on your skin and try to avoid contact. Even if you come in contact with it hardly anything will happen. The degreased skin looks “white” and dry, use a lotion or a similar product for regeneration.

    The

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