Homebrew PCBs

I don't know what this is called, but I assume there are folks making PCBs
this way:

1: Coat the copper board with a thin film of lacquer
2: Use a laser to selectively burn away the lacquer leaving bare copper
3: Etch

Can anyone point me to info about this technique, especially what kind of
lacquer to use, and an idea of how much laser power would be needed. I've
noticed that I can get dark materials to smoke with about 100mW of laser
power. I guess that with the right lacquer, this technique could be done
with about 1 Watt laser power, which is easy to obtain.

Obviously, the laser would have to be mounted on some kind of x/y plotter
device.


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