Danny Miller <dannym@...>
Had a guy experimenting with painting onto PCB for a resist, then burning it off on a CO2 laser cutter in raster mode and chemically etching it.
Later I looked and realized we had significant lens damage. And we've had damaged lenses before, but always because they got smoke into them. This was clean but cracked from heat. And oddly... a small hole drilled through the lens from the bottom side.
Well copper is a really effective reflector of IR used in CO2 lasers. It depends on the degree of polish on the board beforehand and the power settings used... but the results are telling me it's not a safe process.
Cautionary tale right there.