PCB Engraving

[PaioX]

Hi,
I would like to know if it's possible to "engrave" a PCB with a 80W laser cutter. It's really annoying to etch pcb with the classic metod, and i'm searching for someting new and faster.

[epineh]

I think the copper plays hovoc with the laser (Co2), acting a bit like a mirror, which I guess would be a problem.

Have you thought about printing directly :

http://www.cnczone.com/forums/showthread.php?t=30951

Sorry but it is a LONG read.

Russell.

[PaioX]

i don't want to modify a printer...
mmm what about if i print a copper-plated pcb with a black ink and then use the laser to remove it?!then i procede with the acid etching!do you think it could work?

[Pete Stenabaugh]

I think that if you coat the copper with something like a water based paint that will reduce the reflectivity you might have some success. It may even take a couple of runs at it to cut through.

I have also heard that if you use an inert gas like nitrogen or argon in place of your compressed air supply that you can get more cutting power from a 80W laser, and therefore perhaps do some cutting on thin metals. It is something that you would have to experiment with.

Pete

[picbits]

I'd have thought you'd be better off using some kind of coating which you could burn off with the laser then just etch it the normal way. Everything I've read about trying to make PCBs with lasers says that its not very practical.

Worth a try though - it could all just be an urban myth

[PaioX]

I think that i will follow this way...any suggestion on what kind of coating ink i've to use?water based?

[picbits]

Personally the first thing I would try would be a board with photoresist on already.

You normally expose the board to UV light, the bits that are masked stay hard while the bits that are exposed to the UV dissolve when you soak them in developing solution - the resist that is left can be dissolved by acetone or sanded off - might be interesting to see if a laser would burn it off without having to go through the developing solution.

You could also try using one of the spray on conformal coatings - I use clear which wouldn't absorb as much of the lasers power but you can get them in a dark green colour. If you burned off a layer of this leaving bare copper it would go through an etch tank without a problem.

[Pete Stenabaugh]

Well, that might be fine, but the whole idea is to reduce those unnecessary steps, whereby you can go straight from the cad file, and print it to the laser, and then poof you are done, except for drilling the holes, which I would then do on my cnc mill.

Although using the laser to burn off the resist may also provide the same results, but you would have to do it from the raw file as there would be no way to accurately index the laser to pick up on the previously exposed areas if you were trying that method.

I will be receiving my laser in July, so this is one thing that I want to experiment with. Being able to do this for guys that are prototyping, could be a nice way to make a bit of extra cash.

For production of small runs though I think the photoetch is perhaps better, or get a board house to do them for you, but maybe the laser can be used if it is fast enough.

Pete

[rdarlington]

Yes, you can engrave. The question is "why" ? Using photographic techniques is infinitely faster and and will get you much higher resolution (the cutter will tear thin traces off the board). I use pre-sensitized boards with photoresist on them and get them from www.circuitspecialists.com. You print out your pcb pattern on transparency film, put the toner side against the board (you can do this in a well lit room, they're not *THAT* sensitive) to eliminate light leaking around the toner. Then you place a sheet of glass over the transparency to hold it flat against the board. Expose the board using a $6.00 WalMart fluorescent light -or any fluorescent light. 6" distance for about 10 minutes. You could go with a $350 UV lamp box, risk cancer, ruin a lot of boards (90 second exposures leave you very very little wiggle room. perhaps 80-100 seconds is your window vs 8 - 12 minutes with a regular light). Once exposed you "develop" the boards in either commercial developer or about a 5% sodium hydroxide solution. Commercial stuff costs roughly $0.25 for enough to do about 10 3"x5" boards. Etch, drill, done. You can see pictures of every step on my website here:

http://www.x-division.com/gallery/v/...cs/pcb_how-to/

[Ropsch]

Hi, guys,
I am also thinking about using my Redsail engraver for making the protective coating for etching pcb-s. I am not yet quite statisfied with my results, but I think it is a matter of finding the right coating material.
I have tried two different spray colors, just the cheap ones you get around the corner. I sprayed the copper side of the pcb-s, then removed the paint with the laser. It looked like it is ready for etching, the parts where the paint was removed, loked clean. Unfortunately there was still a layer of transparent leftover from the paint, which the acid could not etch through. It worked somehow, when I left the pcb-s in for etching over night, but there were lots of failures in the pcb.
However, I hope with some tyring this should work fine.
I will let you know.

[Ropsch]

It had success today: I sprayed heat resistant paint on the pcb-s, then engraved the pcb pattern into it. The parts where the laser burned the coating away, became black, I removed the grime with alcohol, and etched the pcb as usual. It turned out fine with sharp edges and good details. The heat resistant paint worked much better than the acrylic paint I tried last time.
I am also thinking of using the laser for marking the holes, for easier drilling. I will have to edit the bitmap file, and place the board back to the same spot in the machine, after etching.

Ropsch

[RoboticsMD]

I think straight from laser cutter to PCB without chemical etching deserves some experimentation.

I got a laser cutting machine (a specialized, customized one: Flourine-Krypton-Neon) at the lab, and it cuts through thin copper plates very easily. It is just that the laser machine is for micro machining and the stage size is a bit bigger than 1"x1" (that is right, one inch by one inch, not one foot by one foot)

Shouldn't cutting thin copper with "regular laser" 80W be possible?
I am highly interested in this method.