Cannot consistently etch copper

[Shirtsy]

I tried the settings you suggested on my own F1 ultra and the copper etch is highly inconsistent, sometimes only very lightly engraving the surface for one or two layers before the laser seems to lose effectiveness, or sometimes leaving almost no mark at all.

I've found that adjusting the focal point to be about 3mm above the board seems to work for some reason, but this is obviously not an ideal solution due to the loss in resolution. I have of course tested on a variety of other materials and this quirk only seems to be present with the various PCB substrates I've tried, the focus appears to be correctly set when etching or cutting anything else.

Was there any particular trick to getting a consistent copper etch?

[joshop]

YMMV but when I tried this, I had to very extensively clean the FR-1 board I was using with IPA and fine-grit sandpaper, there must have been some kind of protective layer on top. Without doing this, it barely even made a visible mark on the copper. Worth noting was that I was actually able to use FR-4 with the machine with no difficulties whatsoever, as long as I cleaned the board well afterwards, so you could give that a try too.

[timbot]

@joshop how long did you spend cleaning/sanding the board?

I've tried sanding/cleaning some Bantam FR-1 for up to a minute and it just seems to etch for the first 1-3 passes. After that, there is no visible effect from the laser, and there's still a lot of copper left (tested by measuring continuity - the whole plane is still connected).

[timbot]

Last night I had a (figurative and literal) breakthrough - I was able to get to the substrate layer by running multiple rounds of engraving and cleaning the board in between.

I'm running more experiments but I suspect copper particulate is building up on the board and I need more airflow to clean it out. I am not running an AP2 at the moment, but I am guessing @sphawes is.

I am also going to try different speeds (power is maxed out in the example settings), etc.

[timbot]

Reporting back after more experimentation: the boards really need to be roughed up. Try using a heavier (lower grit) sandpaper like 400 or 320, and going in spirals. I was finally able to engrave/cut some single sided FR-1 I had lying around that in it's untouched state would barely even register a spark.

I'm going to try using an orbital sander and various grit sizes, along with maybe a jig to hold the boards in place.

I don't know what FR-1 stock Stephen was using but it's definitely not the case that boards are ablatable out of the box. When smooth, they just seem to reflect/absorb the laser energy.

[timbot]

Sorry to turn this into my personal blog, but here are some more updates:

This morning I was having all sorts of trouble etching the traces, and no matter what I did it didn't make a difference.

I left the machine for an hour to run an errand, came back, and just re-ran the program I'd been trying to run previously. The green flash of ablated copper lit up immediately.

After a bunch more experimentation, I've determined that the machine/board can only engrave for 6-8 minutes. If I stop the program and re-start 30 minutes later, I get another 6-8 minutes.

I am going to run some more experiments. I may have a faulty machine, or maybe the boards need to be cooled, or maybe my board configuration is messed up (I have a lot of ground planes - maybe the constant fast on/off switching is what is causing things to overheat?).

[matteliot]

Fwiw- I've also tried fr-4 under a thin layer of water to no avail (though I didn't exhaust all the settings), and various colored sharpies. The sharpies did well but I probably need to play with the power settings- it was burning the copper too well. I've also tried copy foil/tape as thin as I could find without any better result. My further investigation says that a UV is actually way better of a wavewength- and also there are no galvo c02 systems. I'm trying to get .1mm traces o my jpt mopa and have been totally unsuccessful, regardless of trace- the copper doesn't want to ablate a bit, it's nothing unless it heats up and then it's blacked char. It works better at the edges than the center, so I'm guessing that's heat disbursement and may try the water idea again.

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On Fri, Feb 7, 2025 at 6:15 PM Tim Smith ***@***.***> wrote: Sorry to turn this into my personal blog, but here are some more updates: This morning I was having all sorts of trouble etching the traces, and no matter what I did it didn't make a difference. I left the machine for an hour to run an errand, came back, and just re-ran the program I'd been trying to run previously. The green flash of ablated copper lit up immediately. After a bunch more experimentation, I've determined that the machine/board can only engrave for 6-8 minutes. If I stop the program and re-start 30 minutes later, I get another 6-8 minutes. I am going to run some more experiments. I may have a faulty machine, or maybe the boards need to be cooled, or maybe my board configuration is messed up (I have a lot of ground planes - maybe the constant fast on/off switching is what is causing things to overheat?). — Reply to this email directly, view it on GitHub <#1 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABKR73NF353HRZGQWZFGNT2OU5BTAVCNFSM6AAAAABVFCQFMKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDMNBUGMYDCMZYGE> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[joshop]

It's interesting that FR-4 has been so tricky for most people, since my experience (on the F1 Ultra) was about as painless as FR-1. I had to make sure to hit it with plenty of fine-grit sandpaper and IPA beforehand, and it looks absolutely awful - the charring makes it hard to even tell if the traces are there or not. Once you sand it and IPA it again, though, it all comes off in the wash and the traces look beautiful, like below (and are actually isolated/continuous).

[timbot]

It turned out I just had a dud F1U - it wouldn't hold full power for more than a few minutes.

xTool sent me a replacement unit and now I am able to etch / cut with Stephen's settings. Easy peasy.

[GJKrupa]

I've found that adjusting the focal point to be about 3mm above the board seems to work for some reason, but this is obviously not an ideal solution due to the loss in resolution.

This worked for me as well on some FR-1 boards I bought from Amazon. Had to up my traces to 0.6mm to compensate but after doing this it etched the copper after about 4-6 passes instead of the suggested 10. I've tried thoroughly cleaning and sanding the boards but it always just seems to mark the copper (and not very evenly at that) when the focus is on the surface.