Laser Blasts Out High-Quality PCBs

With how cheap and how fast custom PCBs have gotten, it almost doesn’t make sense to roll your own anymore, especially when you factor in the messy etching steps and the less than stellar results. That’s not the only way to create a PCB, of course, and if you happen to have access to a 20-Watt fiber laser, you can get some fantastic homemade PCBs that are hard to tell from commercial boards.

Lucikly, [Saulius Lukse] of Kurokesu fame has just such a laser on hand, and with a well-tuned toolchain and a few compromises, he’s able to turn out 0.1-mm pitch PCBs in 30 minutes. The compromises include single-sided boards and no through-holes, but that should still allow for a lot of different useful designs. The process starts with Gerbers going through FlatCAM and then getting imported into EZCAD for the laser. There’s a fair bit of manual tweaking before the laser starts burning away the copper between the traces, which took about 20 passes for 0.035-mm foil on FR4. We have to admit that watching the cutting proceed in the video below is pretty cool.

Once the traces are cut, UV-curable solder resist is applied to the whole board. After curing, the board goes back to the laser for another pass to expose the pads. A final few passes with the laser turned up to 11 cuts the finished board free. We wonder why the laser isn’t used to drill holes; we understand that vias would be hard to connect to the other side, but it seems like through-hole components could be supported. Maybe that’s where [Saulius] is headed with this eventually, since there are traces that terminate in what appears to be via pads.

Whatever the goal, these boards are really slick. We usually see lasers used to remove resist prior to traditional etching, so this is a nice change.

46 thoughts on “Laser Blasts Out High-Quality PCBs

    1. having your CNC mill or Laser do it is vastly better in man hours – you spend the same amount of time plotting and laying out, then just let the machine do most of the work for you (also machines are far easier to get great double sided boards with).

      Manual mask transfer, fixing the imperfections, and then etching all take supervision or active human participation.

    2. Q: light-curable resins are a daily thing, why you no make resins that have ions handy for electrode-less metal plating?
      Plated through holes are made this way: chemicals infused to the inner part of the via-hole cause metal to plate up from a bath.
      If a resin could do the same trick, one could print traces, plate them up in a simple bath, and not have to burn anything away.
      Additive engineering is the future…

        1. Well, it’s not dirt cheap. Not long time ago price tag was about $5k and local greedy distributors charge 20k for similar spec machine. So it makes it “pretty cheap” :)

      1. You can paint a PCB board and use the laser to blast off the paint, then etch as normal.

        This works, although the spot size on the laser at my makerspace was too big (couldn’t make a trace that goes between two 0.1″ pads).

        Looking at the Sarbar videos, it would *appear* that a well tuned CO2 laser system could etch thin enough lines for this. Getting any laser that well tuned would be a project in itself, but if you could pull it off it would be a tremendous benefit to hackers.

        If you want to experiment, you can start with regular black spray paint, and bake the board to be sure all the paint is well dried.

        I’m going to experiment with my SLA printer soon, since that has a lot higher resolution. Should be able to lay down a single (or small number) of layers directly on a copper board, then etch from that. SLA printers are very cheap right now.

  1. > Maybe that’s where [Saulius] is headed with this eventually, since there are traces that terminate in what appears to be via pads.

    that, and there’s also the possibility of vias still being much quicker and easier to drill using CNC.

  2. For vias: the ink from CurcuitScribe pens ($6.99) will connect traces from one side to the other with sub-Ohm resistance. Along side our prototype silver ink printers (which don’t drill holes) we have historically used a LPKF (pcb mill) for prototyping. Capillary action pulls the ink through so hole-diameter and hole-roughness do matter. We don’t have a fiber laser to test with.

    I work for the parent company of CircuitScribe: Electroninks.

  3. When I read “single-side boards, no through-holes”, that’s where I lose interest.

    The technology is impressive, but who wants a single-side board?

    I looked at an Arduino Nano clone, a pretty simple board, and it’s a 2-side board with 92 vias.

    1. Double sided should be trivial with a jig.
      On my 405nm ‘exposer’ I am working on (when I have time) I simply flip the board over and align at the opposite side of the jig, which is a known distance from the other alignment edge.

      My software then simply flips the calculations and I get excellent alignment.

    2. I can do double-sided boards by aligning up paper with toner on it — it should be a no-brainer for a CNC laser. Home axes, put board in registration fixture thingy, done.

      I bet Saulius just hasn’t tried it yet. But now that he’s playing around with vias, I’m guessing it won’t be long.

      I also like the cover-it-all soldermask approach, etching away the bits you want clear. I would have gone with a UV laser and cured the parts to keep, but that would take a lot longer just due to relative surface areas.

      1. Elliot, thank you for noting about double sided boards. Sure, these can be rolled out by symmetrically flipping vertically. It requires very little preparation.

        Of course we can contemplate about DIY double-sided boards with plated vias, my ultimate goal was to have simple high pitch PCBs for rapid prototyping.

        Company where I worked earlier had full LPKF toolset for milling, plating and laminating multi-layer PCBs. I can say that multi-layer press was turned on only once – to try if it works… plating bath was used more, but even being commercial grade equipment sometimes it was a pain in the ass. PCB Milling CNC was a life saver in terms of rapid prototyping and testing design.

  4. This style of laser uses a galvanometer to scan the beam from a fixed position through a lens. For most of the board, the beam is not perpendicular to the board, so using the laser to drill the bias will result in the bias being drilled at an angle. Likewise, when the board is cut free, the edges will have a chamfer on them, the larger the board, the more pronounced the chamfer will be.

    You would need a flying head machine (like how most CO2 or diode lasers operate), our fancy optics to ensure the via is perpendicular to the board.

    1. Note: These machines also use an f-theta lens which flattens out the focal plane and keeps the spot size fairly circular in the cutting region. There will be some aberration, but it’s pretty good. The larger issue is that as the focal plane changes, the cutting region grows/shrinks and _that_ will introduce some taper for sure.

  5. Why is it so hard to find someone who sells fiber lasers? I feel like half the listing on eBay are bait and switch. Amazon seems over priced. And Ali seems to leave all the fees associated with importing out of any descriptions.

    1. Technically import duties and fees are buyer responsibility. Also shipping gross weight is usually above 25kg, which puts it “heavy package” category not suitable for transportation without hand truck or forklift.

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