This is a machine I designed to laser etch pcb’s. I’ve made it so it can do double sided and be easy to align everything when mounting the blanks on the machine. the parts cost of 120 euros, maybe it’s worth making a kit of. I put a few pictures of the results that came from my previous design. I will upload the results of this machine after my uni exams.
Yes I’m working on a dark see through acrylic case, safety is n1. My last machine I enclosed in a metal cabinet during laser work 👌🏽.
Make sure the acrylic is correct for the laser you are using. Just dark does not mean safe - if you are using an ultraviolet laser, for example, you need something that is opaque at that wavelength. The laser should tell you the wavelength it uses (expressed in nanometers - nm), look for acrylic that specifically blocks that wavelength. It is entirely possible to have a piece of acrylic that you can hardly see through, and still burn out your retinas because while it was opaque to the visible light, it was transparent to the invisible light where the power usually is.
The piece I have for my engraver - which uses a laser that is somewhere around 450nm as I recall - is tinted an orange color. Ultra-violet starts about 400nm and goes to around 100nm. At the other end, infrared starts around 800nm and the wavelengths get larger from there. If you have fiber internet service, that typically uses wavelengths in the 1300+nm range - without my cheat sheet, I don't recall the exact wavelengths. I do know the infrared fiber transceivers I used on multi-mode fiber were at 850nm and there was a visible component to that, but the energy itself was invisible.
Hey, thanks for the info it’s really true. I’m still researching the cheapest solution that’s 100% safe. There’s polycarbonates ready that can be used for covering engravers but it’s not cheap. If you have any suggestions of any polarising paints that would be awesome. Also, this engraver reflects upwards a hell lot of light because it reflects off the copper when it burns the paint so it’s basically crazy without a cover.
I'm assuming you lasered the photoresist and then etched them using acid? That laser module doesn't take the copper off, does it?
No, fiber laser is required for that 💸
I've got a 100w fiber mopa and cannot get it to do that- in fact, it barely touches copper at virtually any setting.
Any ideas?
Not OP, but I've had success with a 20W MOPA, so here it goes: Make sure to read through the (frequency,pulse width)vs max power chart. If you know the model of your laser, it should have it attached, or if it's like the laser I used, it might be in the manual (called "power down frequency", weird name but ok). If you try using the laser at a 10ns pulse width at 20kHz, it will not deliver the actual power you requested, as the laser will decrease the power in order to stay within the safe operating zone. It's something that might not be talked about a lot with MOPAs, but it's important to know that a shorter pulse needs a higher frequency. One of the advantages of shorter pulses, is that you might get even higher peak pulse power- also unintuitive, but makers of fiber lasers know their shit, and they have tuned the laser well, including output waveforms for the MO laser. Those things took a while for me to figure out, but it can help you get better results, even with other things than PCBs.
Other important things are focus and the field lens you use, copper really doesn't want to absorb 1064nm light, so you need to get your focus down really well (I'm talking 10s or 100s of micrometers of height difference). As for the field lenses, a 300x300mm filed lens might be nice for engraving large things, the spot size is larger than one with 150x150mm field. There might be other factors than that, but I'm not an optics guy, so in short: small field size means better engravings but tighter DOF (harder to focus), larger field size-> worse engravings but more lenient focus.
Other than that, you really need to just test what works best- do a material test pattern on a scrap PCB, and vary the height between runs a small bit around where your laser says it's in focus, as it is really that critical.
Last thing is the substrate you work with, FR4 likes to char and burn, but FR2 and some mystery RF substrates I tested seemed to survive better. Even if you get the copper to ablate, you will still damage the substrate, but the severity depends on the type.
That was a very long, and probably barely coherent reply, but I hope it ends up useful. Best of luck with the PCBs!
that was all useful, thanks.
I've now spent an immense amount of time on it with no satisfactory results. Best I can do it a tight-focusing theta to concentrate the beam, then 1ns (the minimum) at 72k (the max power per the manufacturer) and I can wobble and punch through the copper but then it all burns after that.
I also noticed that at the edges, there's less heat disbursement so it punches through more easily, in the center, it doesn't.
Using a sharpie marker to darken it helps, but that's not really repeatable.
I've only tried fr4 and the thinnest copper foil I can find.
But I'll try some of your suggestions. Thanks
Really? I’ve cut 3mm copper with my 50w
what settings and which lens???
70 and 100 mm. I can’t recall exact settings, I don’t really save them lol. But I created a 1mm offset around my parts, filled it in and used that to cut. 600mms, 100% power, 50khs (mine is a 50w raycus so that’s my strongest frequency). 0.03 mm hatch, flood fill, rotate hatch 37 degrees. Every 5-8 passes throw in a few cleaning passes. And just repeat till it cuts.
I've got a jpt, I'll monkey with it- let you know how it goes.
Thanks
Is it a fiber laser? This is very interesting if it’s not fiber laser and would like more information on it if you don’t mind.
It is a fiber. 50w raycus source from BOGONG CNC
Yeah that’s the best option when it come to pcb or any metal engraving. Since I can’t afford it now. I go with the laser then chemical method. But the fiber laser just seems like a paradise for makers.
I’m absolutely obsessed with mine lol
what benefit does this have over say one of those commercial laser cutters? Ray5 for example? Cost?
Probably nothing, as is common with DIY electronics. It's pretty cool either way.
There’s a small difference only in the logistics of use. 1. The moving parts have way less inertia than most laser cutters, this comes with the trade-off of smaller bed which Is fine for most pcb, reason is for faster engraving at lower stepper motor power. (Acceleration * mass ) = force —- so acceleration is ( force / mass ) = ( stepper motor force / moving part mass ) = maximum acceleration. so less weight in the moving parts, pulley belts holder etc.. the lighter it is the less the motor works and the faster it can accelerate. 2. This is the most important part, mounting the pcb, the machine can mount 50x50 100x100 150x150 mm pcb, it mounts it with 4 screws tightly so when the top layer is etched all you have to do is flip it over invert the bottom layer in cam software etch again and it’s ready to dip in acid. Double sided pcb engraved in 5-10 mins 🙂.
Small differences but when making a pcb it makes a difference. I made a machine that used lead screws and mounted pcb with clamp and it was kind of annoying to make pcb with and was only practical for single sided. I made a double sided but it took me 4 hours and I had to glue two single sided boards on each other which is not worth it to me.
So what does the acid do? This is all facinating btw. Do you think a 5w laser would work or is 10w required?
5w will do, even 1 w since you are just engraving into blackpaint which requires very little energy. Infuse but more power so I can engrave at more speed. The acid corrodes the exposed copper I’ll probably test it today if I get a box that suits it as a temporary enclosure. Ill post pictures of the process so it’s easier to understand.
Does it burn copper or exposure photo resistive film?
Paint it black most paint works for me aslong as I clean the blank well Then it burn the copper and the exposed copper gets chemically etched by a simple cheap solution.
I tried with black spray paint and it didnt work, what paint do you use?
What resolution can it make? Making footprint of TQFP with 0.5mm pitch possible?
And what about large areas without copper - how long it will take?
Some years ago I made a raster LDI machine, it uses UV laser to exposure resist film. It works cool and fast, but the hard part of the process is applying film to copper. Then developing it before etching. Your process looks faster and more simple.
Video of same type machine (not mine, but raster too) https://www.youtube.com/watch?v=YOX5nSpm-Rs
So cool! Can you share the blueprints/design? What code do you feed in? What do you use as controller?
Grbl to send the gcode, for stepper driver I use ld293d with a rp2040 to control the pwm into steps for stepper motor ( cheapest option ). Many options are possible tho, only reason I make the drivers and so on is so I can read the numbers with more ease and have to read less datasets. I’ll post when I release all the 3D parts and codes 🙂
Looking forward to the update! Nice job...
Thanks
Very nice! Hope to be doing similar one day. :-)
It will be opensource 😁
Even cooler yet. Will keep an eye out for it then. Thanks for the update. :-)
Very cool. A similar project is on my absurdly long list of projects.
And the long list keeps getting longer 😂, thnx btw
It's always better to have a list of possibly useful things to do than not.
-Random ADHD guy
For the sake of your remaining eye - do build a proper enclosure for this gizmo!
All it takes is an unfortunate reflection and you or someone else nearby will get hurt. You can't expect everyone around you to be wearing laser safety glasses (yes, that does include eventual pets too).