Anyone tried to do PCB's with Laser?

[Kim Vellore]

Has any one tried to laser mark the traces for a PCB using a laser for etching with Ferric Chloride. I am guessing Vinyl as a mask would work.
Kim

[Matt Warfield]

Kim,

What does PCB stand for? In my world, it's a Printed Circuit Board and wouldn't recommend lasering, drilling, or cutting these in any way unless they are single layer boards. Reason being is that there is typically a ground plane in one layer and the PCB would have a good chance of shorting out after modification. But then, if the PCB isn't going to be used electronically, then there really aren't any issues there. :rolleyes:

Matt

[Joe Pelonio]

I don't know anything about the electronics of PCBs but have done a few. In my case they were brought in with a rectangular area screenprinted in white ink in a corner, and I merely engraved the lettering by rastoring off the paint. Didn't take much power.

[Mike Hood]

I've done lots of PCB etching over the years (pre-laser) and I'd imagine the easiest way would be to mask with a light coat of paint or plastic or vinyl, and then etch the material away wherever you want the etching solution to remove the copper. You could also then micro-drill the boards once the pads are etched.

[Dave Jones]

I've etched a number of boards over the years (pre-laser). I used various types of resist, ranging from photo-resist to paint. Most worked fine if the detail wasn't a big deal. Some materials wouldn't hold up so well to todays fine pitch SMT layouts.

I have no idea if it would work, but since PCB photoresist is usually UV exposed, it might even be possible to expose it with a laser turned way down low. (just a wild guess) Other than that, paint would probably work. Vinyl maybe (it would depend on the adhesive not letting the acid underetch).

As far as Mike's though of micro drilling. Don't count on it. I have done some tests with PCB fiberglass in my 45 watt Epilog, trying to cut the board material where there was no copper, and it did not go well. It burned like crazy with big flares (even with air assist) and using full power and a very slow speed I did not get through 1/16" FR-4 (it IS fire retardent after all). I ended up with a ton of char and never made it through the fiberglass.

[Rodne Gold]

Easy to etch using a laser and you can get some real fine detial, You can use polyester vinl as a mask (the shiny gold and silver vinyl is normally polyester - if it doesnt stretch its not pvc)
You can even just spray paint and use that as a resist.
HOWEVER you face one major problem , the laser will not take the resist off without leaving some residue , whichever way you go. Thus the etched surface is NOT 100% bare metal and your actual etching is not perfect - its patchy due to the mordant (the etching "acid" ) not reaching the metal where the residue is.
2 ways to solve this , if using paints , use a very soft bristle brush and household cleaner with an mild abraisive (like handy andy) and lightly scrub the piece , the residue comes off and you can then etch. Problem is , that the paint can flake off if there is very fine detail (generally using a scotch pad on the copper substrate will make the paint stick more to it) and the other problem is the fact that warm ferric lifts a paint resist quite easily so you might find the resist coming off during the etch.
The vinyl mask is better however to clean the residue where its vaporised can only be done with a sand blaster (obviously using fine grit)
so that process requires both a laser and a sandblaster.
Heres a copy of a post I have made in the past about laser "etching"

http://www.engravingetc.org/forum/messages.php?webtag=EE&msg=1144.3

[Shaddy Dedmore]

Could you run a second pass to help clean up residue?

Shaddy

[Rodne Gold]

No , any residue , even the oils left on it by touching it with bare fingers after cleaning will act as a resist.