Material approval request: flat black krylon primer for etching resist on copper

Hey, I have a colleague who is interested in using a laser to cut a design into a resist for copper etching. Something like this: https://www.youtube.com/watch?v=OTGZcY7WyYI only with FeCl, but that’s beside the point for this post.

The MSDS for Krylon flat black primer https://www.krylon.com/document/SDS/en/US/724504016021 lists CO2, CO, and metal oxides as the decomposition products. The listed ingredients are all chlorine free. The metal oxides would be coming from the small amount of magnesium in the talc. Is this a thing we could reasonably do on this laser?

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something’s a bit wonky with that MSDS link - it seems to be intended to go here?

yes, that looks right.

(Speaking on behalf of the LCC)

Thanks for bringing this to the LCC!

There’s a two part answer here:

  1. Flat Black Krylon Primer looks fine for lasing once dried, and is approved if used on an approved material. Please ensure it’s fully dried before lasing.
  2. copper boards are very not approved, and should not be put in the bed of the laser. Reflective metals in the cutter bed is a hazard, and copper in particular is bad news with CO2 lasers - strait copper is reflective enough that it gets used for beam path mirrors.

From doing our research, we feel there’s an unacceptable level of risk to people in the space and the equipment from beam reflections, even diffused ones, from lasing materials on top of copper. There are lasers with a wavelength that is appropriate for etching copper, but ours is not one of them.

Unfortunately, this makes the VHS laser cutter unsuitable for etching circuit boards directly.

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cool beans! Thanks for looking into that for me.