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.

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Fun With A 200-kW Fiber Laser

We’ve all heard the “Do not stare into laser with remaining eye” joke. It’s funny because it’s true, as pretty much any laser a hobbyist can easily come by can cause permanent damage to eyes unless the proper precautions are taken. But a fiber laser with 200kW peak power is in another hazard class entirely.

Granted, outsized power ratings like this are a bit misleading, based as they are on femtosecond-long pulses. And to be sure, the fiber laser that [Marco Reps] tears down in the video below was as harmless as a kitten when he got it, thanks to its output optics having been unceremoniously shorn from the amplifier by its former owner. Reattaching the output and splicing the fiber would be necessary to get the laser lasing again, but [Marco] had other priorities in mind. He wanted to understand the operation of a fiber laser, but the tangle of fibers on two separate levels inside the chassis was somewhat inscrutable. The coils of fiber wrapped around the aluminum drums inside the chassis turned out to be the amplifier; fed by a semiconductor seed laser, the light pulse travels through the ytterbium-doped fiber of the two-stage amplifier, which is the active gain medium where stimulated emission, and therefore amplification, occurs.

With a little reverse engineering and the help of an online manual, he was able to understand the laser’s operation. A laser company helped him splice the optics back together – seeing the splicing rig in action is worth the price of admission alone – and the unit seems to be in more or less working order at this point. Normally the most powerful laser we see around here are the CO2 lasers in those cheap Chinese laser cutters, so we’re looking forward to learning more about fiber lasers.

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