Experimental results from laser etching masks for copper etching

[Dustin Andrews]

Tried with various paints I had handy
Rust-Oleum crystal clear Enamel - Laser vaporized some of it, but no amount of repeats would get the last bit off the copper and it wouldn't etch.
Home Depot brand? Interior/Exterior Royal Blue fast dry spray paint - Lasers right off. Or looks like it does. Still leaves an etch proof invisible film on the board. Kind of pretty. Might make for good plaques and signs.
Krylon brand black paint pen - Laser barely did anything. I turned it up until it started burning but couldn't get a clean etc.
Acrylic "Ceramcoat" black paint - Didn't preserve details and dissolves in etch.
Green Sharpie - no discernible etching with laser
Black Sharpie - could see etching but not get all the marker off
blue painters tape - Oh, wow. Why didn't I try this first!?

blue tape.jpg

[Rich Harman]

I don't know what it is but something is not right. I have gotten far better results from regular old enamel spray paint than any of the pieces you have shown.

Possible causes;

Board not clean: I use a scotch bright pad with soap and water and clean the copper to a water-break-free surface. That means that the entire surface should hold an unbroken film of water. If it doesn't, it isn't clean.

Rubbing the etchant rather than bathing: I put the PCB into a ziplock bag with a small amount of fresh ferric chloride. Just enough to cover the board. I seal the bag with as little air in it as possible. I then put the bag into the sink (or pan) with hot water in it. The ziplock goes into the hot water and I agitate by hand. I can pick up the bag at anytime and inspect the progress.

[Rodne Gold]

http://www.sawmillcreek.org/showthre...ical-machining
Read that thread.

[Dustin Andrews]

Possible causes;

Board not clean...

Rubbing the etchant rather than bathing...

My boards are squeaky clean. I know even a fingerprint can mess up etching. I also switched from rubbing to bathing and tried different etching solutions. I get better results from muratic acid + hydrogen peroxide then ferric chloride.

The blue tape came out pretty good. The traces are quite small and there is nothing for scale in the photos. Also, I didn't quite etch it long enough and I used ferric chloride because it's faster. Because it's faster it's harder to control the etch and this one ended up under-etched. It undercuts easily so I was a little hasty. I am trying again with my preferred etch and I think it should come out nicely. The tape mask is about as nice as I can get with toner transfer. The added benefit is that large areas are completely masked. With toner there are holes in the big areas. I actually think the laser with blue tape should be able to do as good or better than I was doing before.

[Dustin Andrews]

http://www.sawmillcreek.org/showthre...ical-machining
Read that thread.

Nice information. Thanks.