Negative laser etching

[James] has been refining a method of negatively etching metal with a laser. He had been using a product called Thermark which is designed for this process, but it’s quite expensive. He found that paint designed for wood stoves works just as well. To prepare the surface he bead blasted it and then cleaned of the residue and finger prints off with acetone. The board was preheated in an oven before covering it with the spray paint. He ran the laser at 98/100 power and 90/400 speed at a step size of 0.1mm to achieve the results above. This should immediately make you think about making circuit boards. We’d love to ditch the toner transfer and we’re always looking for one more reason to get a laser cutter.

Comments

  1. James says:

    Oi! Don’t give spoilers for my next project! :D Laser etched then chem-etched circuit boards may be right after the shaft encoder.

    Thanks for the feature! I updated the laser cutter speed to 300 after you wrote your post, it gives a shinier result!

  2. Mav says:

    Nothing new I been doing that on my laser for a while , just spray the metal , let it dry then blast off the paint with the laser

  3. osgeld says:

    someone already has an instructable on making pcb’s like this, cept I think they used plain old krylon

  4. Macpod says:

    I wonder if you could blacken the metal with a lit candle and come out with a similar effect.

  5. M says:

    I wonder if you could do colored layers

  6. goffknard says:

    I’ve used toner from a copying machine to achieve similar results to Thermark. Simply lift the cover of the machine, hit copy, and it prints out a sheet of toner. Put the paper toner-side-down on the surface to be marked. Then, laser mark the back of the paper at low power levels, and it burns the toner onto the surface. I did this on clear plastics when I ran out of Thermark.

  7. chiefcrash says:

    @macpod: but would that be etchant resistant?

  8. Mav says:

    Tried it as an etch resist also , it doesn’t work well.
    The Lase abilates the paint just fine but also leaves an invisible oxide residue that prevents etching ,, bummer really

  9. Twerpling says:

    I’ve done this many many times. Standard store bought spray paint doesn’t work very well since it leaves a slight residue that cannot be taken off consistently without damaging traces.

    I have actually experimented with every brand I could get my hands on (something like 10 to 15 separate brands). The one that seems to work the best is “Rustoleum Painters Touch 2xCoverage” brand. You also get far better results if you a) fire the laser when the paint is under water (doesn’t form as much residue) , b) paint two or more coats on the surface (residue can be taken off without damaging the traces).

  10. Amos says:

    What about using other materials for coating? Toner was mentioned, but what about, say, the plastic used for powder-coating?

    I’ve even thought about using wax. It’s not as easy to put on, but it might leave less residue. Making a spin-coater like they use in the CD-pressing and semiconductor fabbing industries might be worth a try… And if you did, you could try all manner of liquids, paints, etc.

    I just thought of something crazy: use liquid clay (aka “slip”) and use the laser to form a ceramic resist!

  11. Drone says:

    “…then cleaned of the residue and finger prints off with acetone.”

    HaD please un-hack your spelling/grammar checker.

  12. ril3y says:

    Cermark is expensive. However it does not provide the effect above. What cermark does it is it goes on to your metal (a slight green tint) and then once you laser it it leaves the black on the metal. What he did was spray paint the WHOLE object then remove the paint. Not the best idea say if you wanted to just do a few lines of text on something metal.

    This is what I have been doing for a bit now.
    Here:
    http://blog.synthetos.com/laser-etched-pcbs-take-2/
    http://blog.synthetos.com/magnetic-linear-encoder-and-it-works/
    http://blog.synthetos.com/musamp/
    and here
    http://blog.synthetos.com/pcb-cyborg-art/

    Black Car primer works the best for me.

    Ril3y

  13. Renee says:

    How can this be used for pcb’s? Aren’t you just removing the top layer of paint to reveal metal underneath? I mean isn’t it still just one interconnected piece of metal?

  14. mowcius says:

    Renee, then you etch the board. The paint then acts as the resist material. It’s a very accurate way to do it.

    I have also done this many times but never for PCBs

  15. Laser Toner says:

    Really interesting, never done much with laser etching but seems cool.

  16. Renee says:

    So the etching removes the exposed metal and then you remove the paint? Sorry for the noobish question.

  17. James says:

    @Renee – The terms make it a little confusing. Laser etching removes the paint and leaves exposed metal. Chemical etching then removes the exposed metal, leaving the metal covered by the paint, which are the PCB tracks. Wash off the paint with acetone and you have a PCB!

  18. ril3y says:

    @renee and @James
    reneee.. James nailed it. So your exposed metal is then coated in ferric chloride (or whatever) and its removed. I then use a dremmel with a soft wire brush + acetone.

    Here are exact process images:

    1. PCB lasered to reveal metal (black = traces)
    http://www.flickr.com/photos/rileyporter/4374283832/

    2. Chemically Etched. Paint still on.
    http://www.flickr.com/photos/rileyporter/4373728351/

    3. A PCB is born.
    http://www.flickr.com/photos/rileyporter/4373738883/

    Hope that helps.

    ril3y

  19. Renee says:

    OK, yeah that’s what I thought! Thanks!

  20. bwmetz says:

    Just a crazy idea, but once etched…couldn’t you just leave most of the paint in place to protect the traces from corrosion, etc, i.e. just clean the pads you need to solder too? I think cleaning it all would be less time consuming, but if the paint can protect, it’d be an interesting project to etch a non-green PCB if you could find a contrasting paint color that works.

  21. ril3y says:

    Yup. You could. However I usually am too impatient to hit the 603, 403, smd component pads individually. I also thought about creating a new “mask” that once the board was etched I would place it back in the laser and just remove the pads with the laser. However alignment is hard to get right when you are working with such fine parts.

    ril3y

  22. George Johnson says:

    So dump the TTS method of making PCB’s. I use MG Chemicals pre-sensitized board. They are exposed using regular fluorescent lamps so it’s really easy to make single and double sided boards simply by printing out the patterns on clear transparency sheets. Works great.

    Also, they make a Plated Through Hole kit for hobbyist!! I haven’t tried it out yet, but it’s a kit that sells for just under $200 I think.

    I could NEVER get the TTS method to work. As much as I tried, it’s just one of those things I could just never get quite right.

    Once I found the MG Chemicals boards, I never looked back. Use those, then tin plate the traces. Then spray it with that green acrylic paint. Use the TTS system to lay on a silk screen of components, and you end up with a VERY professional looking board. You can even get a small, cheap gold plate kit to do your own push buttons (like on a TV remote) or edge connectors.

  23. George Johnson says:

    So what are we using to LASER etch the things with in the first place?? I missed something somewhere.

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