Making circuit boards with laser

[Niklas Bjornestal]

Is it possible to make circuit boards using the laser insteadt of photoresist? Eg. paint(?) the board, laser away the paint and then etch to remove the exposed copper?
If it is possible will the quality be as good? and what paint to use?

[Gary Hair]

I had a customer who made copper art pieces and he had me laser away paint so he could etch his designs. I'm not positive what brand of paint he used, but I think it was Krylon or something similar. It worked really well, he liked the results and the details were really good. Not sure how it would work for a circuit board, but I can't see why it wouldn't work.

Gary

[Graham Symns]

In short the answer is yes.
Start with clean circuit board,coat the board with a resist of paint say acrylic paint.
Use a short focal lens.
Raster it using the best resolution ie DPI that your laser offers.
Test the power and speed on a test peice.
Don't forget to invert the image and reverse it.
This presumes that you design the board viewing from the component side.
I use ammonium persulphate (I bought a 20 kg bag of it some years ago) and use a bubbler and hot plate to raise the solution temperature to about 50 degrees centigrade.Suspend the PCB in the air stream and keep an eye on it until all copper to be etched is gone.
All that said I now use the toner transfer method.
Best of luck.

[James E Baker]

Back in the 70s, I used to run a small PCB manufacturing facility.

In the early days we used a silk screened paint as the etch resist, so any good coverage tough paint (I'd use an enamel or laquer), but something like an auto chassis paint would probably be better. Raster LASER the paint off in the area you want to etch.

For etching, we used a glass fish tank held together with silicon with a bubbler system consisting of PVC piping drilled with holes fed from an air supply (we used an old vacuum cleaner on blow but a compressed air supply regulated down to about 5-10 psi would be better). The etch sollution was ferric chloride, and we kept it hot with 2 glass encased fish-tank heaters that had the thermostats bypassed (the temperature should be as hot as you can stand). You need both heat and agitation for quick etches with a minimum of undercutting.

Ferric Chloride will eat practically anything except glass, PVC (it does discolour it), silicon and titanium.

[Rodne Gold]

I do etching using a laser and resists - there is one major problem doing stuff this way and that is that the laser does not entirely remove the resist. The etching does not work at all well unless you have dead clean metal - even a fingerprint will show.
So whatever resist you use - you MUST clean the laser engraved surface - I either use a ployester "vinyl" resist and sandblast after laser ablation , or if using paint , I use handy andy household mild abraisive cleaner rubbed on by hand to clear the residues left by the laser.
Search for the term Ferric chloride on this forum , I and others have posted before about this